best magnetic separators wet sticky copper ore

iron ore magnetic separation

In the West, capitalists have expended many millions of dollars developing the low-grade porphyry ores of copper. Half a dozen of these great enterprises have proved to be wonderful commercial successes. They have demanded improved crushing and concentrating machinery and consequently it has been developed. Many improved methods, cheap power, superior business organization, all these have contributed to this success, but the main feature is the handling of the material in enormous quantities, on a manufacturing scale. The mining chance of striking it rich has been eliminated by the manufacturing certainty of handling large quantities of material of known value, which while of relatively low grade, is available in large tonnages, assuring a supply for many years run of the mill. Then the returns on the money invested are sure.

The concentration of low-grade magnetic iron ores, separating the magnetite crystals from the gangue by the use of magnets, is a field of work in which the lessons taught by the development of the porphyry coppers can be studied to advantage. Large-scale operations, and the liberal expenditure of enough money at the start to insure the most economical operations, are the means of securing the desired results.

The problem is to utilize millions of tons, and we may safely say billions of tons, of now worthless iron-bearing rock and to produce from it 10,000,000 to 20,000,000 tons per year of high-grade ore carrying 60 per cent, iron or higher; to take the lean material as found in nature, varying widely in iron content, and bring it up to a uniform standard of shipping ore. At present these ores are mined carrying from 25 to 50 per cent, iron, and the shipping product is brought up to 60 or 65 per cent. Fe. If future economies of operation make it possible to extend this process so that 15 per cent, iron in the crude ore can be treated as a commercial success, the additional tonnage available will be enormous. A 15 per cent. Fe crude ore raised to 60 per cent. Fe concentrate with 5 per cent.

Fe loss in tailings would require 5.5 tons of crude for 1 ton of concentrates. The cost of crushing and concentration can be brought down to 12 c. per ton crude or possibly to 10 c., and the cost of quarrying on a large scale, probably 40 c., would be low enough to leave a profit even now. There are mountains of gabbro rock in the Adirondacks that will average 15 per cent, iron in the form of magnetite crystals of good size, say 1/8 to 1/16 in., but the concentrate would also carry some titanium.

A thorough examination of some of the iron-ore properties and the knowledge acquired by development of extensive underground workings makes it possible to make quite definite estimates of tonnage available in certain areas, which show very large reserves.

F. S. Witherbee in his paper read before the American Iron and Steel Institute last October gave an estimate of 1,100,000,000 tons of crude magnetic ore above 30 per cent. Fe available for concentration in the Adirondack region alone, not including any titaniferous ores except the one deposit at Lake Sanford. He practically confined his estimate to the area of the iron-bearing gneisses which surround the central core of later eruptives, the anorthosites and gabbros, in which the titaniferous ores are found.

There are also in New Jersey and southeastern New York large areas that give conclusive evidence of vast amounts of non-titaniferous magnetites. The map accompanying the report of the State Geologist of New Jersey, year 1910, shows the area of iron-bearing gneiss rocks running northeast and southwest across the State about 18 miles wide by 50 miles long, from Phillipsburgh to Greenwood Lake. In this area are located by name 366 magnetite mines that have been worked more or less. There are also 24 limonite and 8 hematite mines. These lenses may easily be capable of producing an average of 1,000,000 tons each and there are probably double the number listed not opened up. Here we have 900 sq. miles of iron-bearing gneisses in New Jersey, or more than in the Adirondack region, with nearly as much more additional in southeastern New York, reaching from the New Jersey line across the Hudson at Fort Montgomery and extending to Brewsters.

Mr. Witherbees method of computation estimated 20 ft. thickness of ore over 10 per cent, of the surface area. He afterward cut the estimate, in half to be conservative, which was equivalent to 10 ft. thickness of ore on one-tenth of the surface. This would give 2,700,000 tons per square mile or on 900 sq. miles in New Jersey 2,300,000,000 tons, with a goodly area in New York to-fall back on to make up deficiencies.

Magnetic ore is found quite widely distributed, in Canada, Minnesota, California; New Mexico, New York. New Jersey, Pennsylvania, North and South Carolina, Tennessee. A detailed study of these deposits might be an interesting subject for the Bureau of Mines to follow up.

Some time in the, year 1887 my attention was called to the magnetic separation of ores. At that time Edison was experimenting with his deflecting magnet and the Wenstrom, a Swedish machine of the drum type, was in use. The Conkling machine, which was also on the market, was the forerunner of the modern belt machine, but the magnetic attraction came from a single magnetized plate.

My first experiment was with Port Henry old-bed ore, which I crushed to pass through 1/8 in. mesh, and then ran through an old-fashioned fanning-mill, such as are used on farms. I had better results than those obtained by Mr. Edison with his deflecting magnet. I then made a trial of the Conkling idea but found that the magnetic plate picked up a large part of the gangue with the ore, so that the ore had to be sized and fed very slowly to get good results. The same trouble was experienced with the Wenstrom machine.

I then made a small machine, substituting common horseshoe magnets , for the magnetic plate of the Conkling machine. Since the magnets were of north and south polarity the ore turned end for end in moving from one pole to the nextnot only the loops of ore and gangue but each individual piece turning. In this way the gangue was allowed to drop out, the ore was held, passed on to the next magnet, and so finally cleaned of the non-magnetic rock.

However, as I was not an electrical engineer, I went to a friend, Clinton M. Ball, explained the operation of the machine, and told him that if he would make electromagnets of sufficient size and power, of alternating poles, I thought they would be a great improvement over anything previously used. Mr. Ball made the magnets, a small machine was built (shown in Fig. 2), and taken to the Benson mines, where about

The small machine was of the belt type. Mr. Ball soon after designed a drum-type machine, and later a double-drum machine in which a three-part separation was made. There are now magnetic machines of many types, but the majority use the alternating pole magnets.

Mr. Palmers machine is an interesting example of an early crude use of an important scientific principle. It was simple and primitive in the extreme, consisting primarily, of a row of horseshoe magnets spiked around a log, like the spokes of a wheel. Finely crushed crude ore was allowed to slide through a wooden trough underneath the magnets, which were rotated by a crank attached to their supporting log. As the magnets rotated, they dipped into the trough, the good ore became attached to them and was lifted up. It was then transferred to another trough, set above, by employing the simple device of a broom wielded by a husky Irishman.

The number of so-called magnetic separators for which patents have been taken out has been so large that it would be a waste of time even to try to enumerate, them. Many of them were mere toys and a number were mechanical monstrosities. The belt and drum machines of the Ball and Norton patent have accounted for 90 per cent, of magnetic concentration by the dry process; while the wet magnetic process has been entirely monopolized in this country by the Grondal-type machine. There are no patents today controlling magnetic separation, and there is no longer any chance for any now or startling discoveries in this line.

The first magnetic separator that I constructed was of the belt type. It was operated with a feed belt running 125 ft. per minute, while the take-off belt ran 250 ft. per minute. I wished to make a careful test of the capabilities of the machine when working on an ideal material, so I prepared a special mixture for the purpose. This consisted of crushed white marble, washed and sized between 1/8 and 1/20-in. mesh; mixed with iron ore of the same size in a proportion of 2 parts marble to 1 part iron. It was evident that the particles of iron ore and marble would not be attached to each other, since the, mixture was purely artificial. This mixture was then fed to the machine in a stream in. deep. The separation was almost perfect, giving an iron product over 99 per cent. pure. In this way, the possibility of a complete separation was conclusively demonstrated. In actual practice, however, such thorough preparation of material is impossible, and, owing to the difficulty of properly preparing the ore, there are some cases where separation cannot be made a commercial success.

The magnetic iron ores found in different localities vary widely, not only in their iron content, but also in their physical structure. The ores from the various districts require, consequently, radically different treatment.

In the first place, bodies of ore differ widely in crystallography. For example, the ores of the Champlain Valley are more coarsely crystalline than the ores of New Jersey, the Benson mine, or the Cornwall ore bed. Obviously the mill treatment of these ores cannot be the same. Among other things, ore containing the coarser crystals would not require to be crushed to so fine a size as ore of the Cornwall type. It is very important to find the exact size at which any particular ore is most economically separated, and this size can easily be determined by experimental tests in a suitable laboratory. Moreover, the degree of fineness to which the ore must be crushed determines the process of separation to be employed. An ore which must be crushed to 1/8 in., 1/16 in., or lower will require the wet method of separation, while for larger sizes the dry method can be most profitably employed. The exact size that determines the method to be used is also somewhat dependent on the amount of moisture contained. Quite fine sizes can be separated if perfectly dry and fed in a thin film, but the dust problem is then somewhat difficult to deal with.

The largest development in the iron-ore industry, using magnetic concentration, is at the plants of Witherbee, Sherman & Co. at Mineville, N. Y., where about 1,200,000 tons of crude ore were mined and separated in 1916. The dry process of separation is used. The Chateangay; Ore & Iron Co., at Lyon Mountain, N. Y., the Empire Steel &

Iron Co. and the Ringwood Co. in New Jersey, also use the dry process successfully. The Grondal wet separators have been recently installed at the Benson mines in New York. The largest development of the, wet process in this country is on the Cornwall ore at Lebanon, Pa. This work is in charge of B. E. McKechnie, who is the highest authority on the wet process.

In the practical application of magnetic separation the most vital part is the preparation of the ore. It must be crushed so that the crystals of magnetite, or groups of crystals, are sufficiently freed from rock to bring the percentage of iron up to the standard set for shipping ore. On the other hand, it must not be crushed too fine, if it is possible to avoid it, otherwise the blast does not pass through readily in the furnace, or the ore blows over the top.

If the material going to the separators is sized, the strength of the magnets, can be adjusted to pick up the ore of more nearly uniform quality, but a separation can be made without very close sizing.

The pulley-type machine (Fig. 4) has a full circle of magnets which revolve with the drum. The magnets are wound to carry more-current than the-drum machine and will attract any lean ore, throwing off pure rock or tailings.

The drum and pulley machineswill handle 30 to 50 tons per hour and are used together. The drum picks out any ore, as heads, rich enough for shipment. The pulley throws out rock lean enough to discard; what is left as middlings is crushed to about half its size and passed to machines treating finer sizes.

The belt-type machine (Fig. 5) is used when the ore is reduced to -in. or below. The magnets are open to the air, so keep comparatively cool and are easily inspected. Since the magnets of the belt machine lift the ore from the feed belt, the gangue is less likely to be held in suspension and a cleaner concentrate is insured. In the triple-deck machine shown in Fig. 5 the two top machines make heads and the bottom one makes tailings, and middlings to be reground.

If fine grinding is necessary to separate the crystals of magnetite from the gangue, wet separation is indicated. In this case treatment by sintering, or other processes, to agglomerate the ore is also required. The sintering process solves another difficulty by removing sulphur. Low iron and high sulphur content are handicaps which can now be both overcome by the combination of magnetic concentration and sintering.

The accompanying flow sheets of mill No. 3 (Fig. 6), mill No. 4 (Fig. 7), and mill No. 5 (Fig. 8), of Witherbee, Sherman & Co. at Mineville, N. Y., show arrangements for treating, three different ores. The richness of the ore determines at what size the first separation can be made.

The ore must be very dry in order to secure freedom of motion between the particles, or poor separation will result. This condition allows the very fine particles to escape as dust. No system of fans or other arrangements for eliminating or controlling this dust has been developed which can be successfully operated at a cost not prohibitive on this ore.

Owing to the tendency of the fine particles of talcy gangue to cling to the magnetic pieces, it was found impossible to raise the iron constant above 52 per cent, when separating the average grade of Cornwall ore. This fact is demonstrated by washing concentrates from the dry magnetic separation, when the iron content was easily raised from 52 to 58 per cent. This suggested using a combined process of dry magnetic separation and of washing the magnetic product in some such apparatus as the Dorr classifier.

The same or better results could probably be obtained by a wet magnetic separation. This process would eliminate the cost of drying, the dust problem and should give a higher recovery of iron, due to the fact that a certain amount of iron would be lost in the slime from washing of dry concentrates. In the wet magnetic separation this washing is carried out in a strong magnetic field, which greatly reduces the loss from this cause.

In connection with the results obtained from the experimental wet magnetic separator constructed for investigating the wet process of magnetic separation of Cornwall ore, attention is called to the following points:

It is evident that in the separation of any ore by magnetic or other forces, the ore must be crushed sufficiently fine to free the valuable minerals from the gangue, and also that the degree of fineness required in the crushing depends upon the physical characteristics of the ore. As it is impractical to carry the crushing far enough to free all the mineral from the gangue, there will be a certain percentage of attached particles or middlings consisting of both mineral and gangue.

In the case of magnetic separation, these attached particles may go either as concentrates or tailings, depending on the strength of the magnetic field and the ratio by weight of magnetic to non-magnetic material in each. From this it follows that the stronger the magnetic field, the lower in iron will be both the concentrates and tailings product, due to a larger quantity of attached particles being attracted to the magnets. The reverse also holds true, that, the lower the current, the higher in iron will be both the concentrates and tailings as fewer attached particles will go to the concentrates and more to the tailings.

The richer the crude ore, the higher will be the grade of concentrates and the higher will be the iron content in the tailings. This is due to the fact that the rich ore carries a greater proportion of rich particles and a smaller proportion of rock. The grade of concentrates is raised, due to the smaller percentage of attached particles, while the percentage of iron in the tailings is greater, because of the smaller amount of clean rock present to balance the small quantity of magnetic material entering the tailings.

Assuming that the amount of magnetic particles dropped by the separator is a nearly constant quantity, a higher percentage of recovery of iron is obtainable from a rich ore than from a leaner ore as the percentage of iron lost is evidently less.

The wet magnetic separator constructed for these experiments is a drum-type machine, constructed on the Ball-Norton principle. It consists of a number of stationary electromagnets, of alternate positive and negative polarity attached radially to a central shaft. About these magnets revolves a non-magnetic, water-tight drum, which carries a thin rubber belt.

In practice the magnets do not extend the entire circumference of the machine, but a gap is left between the points of feeding and delivery of concentrates. In this machine which was built for experimental work, any desired number of magnets could be cut out by short-circuiting the current around them.

Arrangement 1.The revolving drum drives the thin rubber belt which covers the face of the drum and passes over pulleys. Ore and water, or pulp, are fed by a launder or feed sole in such a manner that the feed is thrown against the moving belt. The magnetic particles are held to the drum, while the non-magnetic material falls into the tank and is drawn off. As the magnetic material held against the belt passes through the water, the influence of the alternating polarity of the magnets is to cause the magnetic particles to take a rolling action, which allows any entrapped gangue to fall out. As the drum further revolves, the magnetic concentrates are lifted out of the water and carried up the belt and around the pulley, where they are washed off by a spray of water.

In practice on Cornwall ore, it was found that a certain amount of very fine gangue was carried by the water into concentrates. They were, therefore, led to a classifier consisting of an inverted pyramid or tank, the bottom of which was fitted with a small hole and a connection above this hole for supplying clean water under slightly greater head than the depth of water in the tank. This water supply was regulated to furnish all the water required to supply the hole or the spigot and to furnish a slight raising current against which the heavy magnetic particles would fall but the very fine gangue could not, but would escape over the edge with surplus water.

Arrangement 2 was similar to 1 except that the water level in the tank was lowered until it was below the drum. This was done in an effort to reduce the amount of dirty water carried over the concentrates. The separator failed to make a separation operated in this manner, due to the fact that the surface tension of the water on the drum caused this water to act as a blanket, which did not allow the non-magnetic material to fall out.

In arrangements 3 and 4, the motion of the drum was reversed and the idler pulley removed. The feed sole was placed above to feed the pulp in the direction of travel of the belt. The tailings were to be removed at the tank and the concentrates, carried past the division board placed under the last magnet were to be removed by the spray of water. Due to the surface tension of the water, no separation took place above the water level. The separation accomplished beyond this point was destroyed by currents set up in the water by the rotation of the drum.

It should be noted that 9 per cent, represents non-magnetic iron, or that about 75 per cent, of the iron occurring in this tailings sample is non-magnetic and cannot be charged to the inefficiency of the separation.

Crude..38.30 per cent, total Fe, 33.64 per cent. Fe as magnetite. Concentrates..58.40 per cent, total Fe, 55.97 per cent. Fe as magnetite. Tails10.20 per cent, total Fe, 2.17 per cent. Fe as magnetite.

The following reports show results of samples tested to determine treatment required and quality of concentrates that could be expected. These tests were run on a regular mill size separator and the results could be duplicated in actual practice. The separate determinations of iron as magnetite, and total iron, were made so that the difference between the two would show the amount of iron combined as silicates in hornblende and other gangue minerals.

307 lb. crude ore was crushed to pass 1/8-in. screen; separated, by screening, into two sizes, on 16 and through 16-mesh. Through 8 on 16-mesh 132 lb., through 16, 175 lb. 8-16 size, treated on belt machine using 3, 4, 5 amp. and finally with 4 amp. for heads. Then 12 amp. for midds and tails.

Crude 224 lbFe Heads 115.Fe 66.15, P 0.005 Tails 108.Fe 3.00 General crude 307 lb.Fe 30.85 P 0.008 General cone. 135Fe 65.60, P 0.005 General tails 171..Fe 3.27

Note.Owing to the iron being present in very small crystals it is necessary to crush this ore to at least 1/8-in before separation, but since the ore is extremely brittle this is easily accomplished with little power.

Note.In order to reduce the iron in the tailings finer grinding through 16-mesh will be necessary at the last stage making a three-part separation on the through 16 size and retreating resulting midds.

The demonstration of the dry process of magnetic separation is the result of 14 years work at Mineville, N. Y. Witherbee, Sherman & Co. have now in operation three mills having a combined capacity of 6,000 tons per day of crude ore. The Empire Steel & Iron Co. and the Ringwood Co. have demonstrated what can be done with New Jersey ores. The Ringwood Co. has also worked out a dry process of jigging for their tailings to recover the martite, which is non-magnetic. Martite is a hematite in composition, but is very similar in appearance and crystallization to the magnetite. Some of the magnetic ores have varying amounts of martite mixed with the magnetite.

The known and partially developed orebodies of New York and New Jersey could, if equipped with the best modern mining and milling machinery and using the best methods, produce at the present time 25,000 tons of 60 per cent, iron ore per day. This can be delivered for an average freight charge of $0.75 per ton from mill to tidewater. The operating cost of production should reach the dollar rock ideal of the Lake Superior Copper region, and the cost of mining and milling 1 ton of crude ore should be about $1 for underground mining when handled in large quantities.

The ratio of concentration would be 2 tons of crude per ton of concentrates for an average. There are reserves of magnetic ore sufficient to double the above production, and then last probably 100 years.

electromagnetic separators for strongly magnetic minerals

Many classifications based on the method of treatment, on differences in construction, etc., have been suggested to include the different types of magnetic separators; separators with stationary magnets, and those whose magnets revolve; separators in which the ore is attracted directly against the magnet, and those which interpose a nonmagnetic belt or drum between the magnet and the particles attracted; separators which lift the magnetic particles from the mixture, and those which deflect the magnetic particles from a falling sheet of ore, and various others. The classification of most value is that based upon the types of material the different separators are suited to treat. For this reason the only classification attempted here is to distinguish between the separators designed to remove ferromagnetic minerals and those designed to treat such feebly magnetic minerals as raw siderite, limonite, etc. A number of separators have been designed to treat a finely divided feed only, and others for use as cobbing machines. The sizes of feed to which the several machines are suited will appear in the descriptions of the individual separators.

Descriptions have been published of a large number of separators whose principal claim to interest is an historical one; the only machines here described are those which are at present of commercial importance.

This machine employs the principle of a series of magnets of alternate polarity to effect a thorough turning over of the ore while in the influence of the magnetic field, thus permitting entrained particles of waste to fall from the concentrate. The ore is fed from a hopper by a feed roll upon a horizontal belt which serves to present it to the magnets from beneath. The magnetic particles are lifted from this feed belt by the magnets and held against a take-off belt running in the same direction and interposed between the ore stream and the magnet poles. The take-off belt is run at a greater speed than the feed belt in order to carry the ore past the magnets in a thinner layer. The belts are made of rubber-covered canvas, and means are provided to

alter the speed of belt-travel to suit different ores. As the magnetic particles are held against the take-off belt, and by its motion carried past the poles alternately opposite in sign, the loops of magnetic particles are broken and reformed as they pass from one pole to the next, permitting entrained particles to fall from the concentrate into a tailing compartment, into which the non- magnetic material remaining on the feed belt also falls. The magnetic concentrate is carried past a partition and is dropped from the last magnet into a separate compartment.

The series of magnets is made up of 12 poles, those of opposite sign being adjacent, all controlled, in the type machine, by one rheostat. By dividing the poles into two series by suitable connections, and employing an additional rheostat, two sections of the field of different intensity may be obtained.

The ore is fed at the top of what may be termed the rougher drum, in passing around which the nonmagnetic particles are thoroughly eliminated, falling into a hopper below. The magnetic particles are held against the drum by the magnets within, and while passing the poles of opposite sign the loops of magnetic particles are broken and reformed, freeing the nonmagnetic particles, which are removed by a combination of gravity, centrifugal force, and the effect of a blast of air impinging upon the surface of the drum in a direction opposite to its rotation. At a point just below the horizontal diameter of this drum the ore passes beyond the influence of the magnets and is thrown, by centrifugal force, against the face of the adjacent cleaner drum where it is caught and held by the magnets. The cleaner drum revolves at a greater speed than the first drum encountered by the ore and is furnished with weaker magnets; particles of inferior permeability, which were held by the rougher drum, are here thrown off into a middling hopper; the concentrate is carried farther and thrown into a chute after passing beyond the influence of the last magnet pole. The rougher drum makes 40 revolutions per minute and the cleaner drum 50; the magnets in the rougher drum take 10.5 amperes and those in the cleaner drum 13 amperes.

The capacity of this separator, with drums 24 ins. in diameter by 24 ins. face, is from 15 to 20 tons per hour of magnetite ore, crushed to pass 16 or 20 mesh. The power required is from to H. P. for operation, and from 1 to 1.5 E. H. P. for excitation.

This type of separator was designed for the treatment of fine material. It consists of a composite electromagnet of cylindrical form which revolves about a vertical axis. This cylinder, of cast iron, carries a series of six exciting coils, wound in circular grooves cut around its circumference. These coils are separated from each other 60 mm., and are so wound as to give fields of progressively increasing strength from top to bottom opposite the iron spaces between the coils, which form the separating surfaces.

The ore, in suspension in water, is fed from a launder against the topmost magnetic ring. This launder, which is curved to cover about 90 degrees of the magnetic cylinder, is supplemented by four other similar launders below it, which serve to catch and return against the drum any material thrown off by its revolution.

The magnetic particles stick to the rings between the coils, those not held by the first ring being caught and held by one of the lower rings, each of which has a field of greater strength than the ring next above it. Nonmagnetic particles are washed from the concentrate by a stream of water which plays against the cylinder. By the revolution of the cylinder the magnetic particles adhering to it are carried opposite a wooden cylinder, carrying secondary magnets, which is mounted parallel to the magnetic cylinder, and which revolves in the opposite direction. This wooden cylinder is studded with a number of iron pegs so placed

as to come opposite the magnetic rings of the separating cylinder. These pegs, distant 5 mm. from the magnetic rings, concentrate the lines of force from these rings upon their points, giving rise to local fields of greater intensity than the primaries, and so cause the magnetic particles to leap across the gap and attach themselves to the pegs. By the revolution of the wooden cylinder these pegs are carried beyond the influence of the primaries, lose their secondarily induced magnetism, and drop their burden of magnetic particles, which removal is aided by a stream of water.

The capacity of this machine is from 30 to 45 metric tons per 24 hours of magnetite ore, crushed to pass a 1-mm. aperture. The magnets require 6 amperes at 31 volts. The separating cylinder makes 25 R.P.M. and the take-off cylinder 225 R.P.M.

This separator consists of two iron disks fastened, 60 mm. apart, to a vertical standard, the space between the disks being occupied by the exciting coils. The disks and coils are stationary. This circular magnet is covered with a brass ring, around

the periphery of which a series of iron strips are mounted; and which are magnetized from the disks as long as they are adjacent to them. The distance between the disks and the brass ring is so varied that the iron strips are magnetized during one half of the revolution only. The ore is slimed and fed, in suspension in water, against the brass ring through launders similar to those employed in the Dellvik-Grondal separator. The magnetic particles stick to the iron strips during half the revolution, are thoroughly washed with a jet of water, and, on passing beyond the influence of the magnetic disks, are washed off the strips by a jet of water. The iron strips are coated at the top with a layer of lead and antimony. This layer is thickest at the top of the strip, gradually shading off until at the bottom of each strip the ore comes into direct contact with the iron; this is done to give a field of steadily increasing strength on each strip in the direction of passage of the ore.

This separator consists of a fixed electromagnet with hatchet-shaped pole pieces enclosed in brass drums which revolve at 80 revolutions per minute. The surfaces of the drums are fitted with strips of iron which form secondary poles, and against which the magnetic particles are attracted. The ore is introduced into a tank beneath the revolving drum, which is suspended just above the level of the water; the sharp edges of the pole pieces give rise to a concentration of the lines of force which serves to lift the particles of pure magnetite out of the water and against the drum, where they stick to the secondary magnets and are carried by the revolution of the drum out of the field and discharged into a launder. The particles forming the middling product are not lifted from the water, but are sufficiently attracted to separate them from the waste and are discharged through an overflow at the side of the tank. The nonmagnetic particles fall to the bottom of the tank and are discharged through pipes. Generally two drums are combined in a twin machine which requires 2 H.P. for operation, and 3.5 amperes at 110 volts for excitation of the magnets. The capacity of this machine is 50 tons in 24 hours.

This type of separator was designed to deliver magnetite concentrate as dry as possible from a wet separation. It consists of a brass disk revolving at 1450 R.P.M. beneath an electromagnet whose pole pieces taper to an edge at their lower extremities. The

slimed ore is delivered by a launder into a tank beneath the brass disk, and the magnetic particles are drawn up against the disk, from which they are thrown off by centrifugal force in a nearly dry state. About 1 H.P. is required for operation, and 3.5 amperes at 110 volts for excitation of the magnet.

This machine consists of a brass drum which revolves on a horizontal axis and encloses a series of magnets of alternate polarity of the Ball-Norton type. The difference between the working of this machine and that of the Ball-Norton consists in

feeding the finely crushed ore in the former case, in a stream of water into a tank beneath the separating drum, from which it is raised by the magnets against the drum. This machine requires 1 H.P. for operation and 4 to 5 amperes at 110 volts for excitation. It is said to have treated 100 tons of crude ore in 24 hours.

This is a stationary electro-magnet with two beveled-edge pole pieces which are suspended above V-shaped settling tanks. The slime, in suspension in water, is introduced at one side of the tank in a shallow stream which flows beneath the pole pieces to a similar discharge at the opposite side. The current on the magnet, which is suspended close to the water level, but not dipping into the water, is regulated so as to be just too weak to lift magnetic particles out of the water. The magnetic particles form

bunches in the water beneath the pole pieces and fall to the bottom of the tank, from which they are discharged through a pipe. This apparatus is frequently employed for dewatering the pulp from ball mills, in which case a stream of clear water is introduced into the tank at the bottom; the sand falls to the bottom and is discharged through a pipe along with the bunches of magnetic slime collected beneath the magnets. By regulation of the velocity of the stream of pulp and the amount of clear water added, the size of particles carried over the waste discharge may be adjusted to suit the ore under treatment.

the edges of the magnetic plates, or disks, of the armature, focusing the lines of force from the primaries and causing magnetic particles to stick to the armature until carried beyond the influence of the primary poles. The waste drops off the armature into a receptacle, while the magnetic particles are held until the neutral point is reached, where the magnetism of the disks changes from plus to minus, when they fall into a receptacle. The change in magnetism is gradual, so that by means of suitable partitions, several products may be made on the same separator, the strongly magnetic being the last to fall from the armature.

The machine is built in one size only, with 30-in. poles, but the magnets are wound for various strengths of current. The capacity of the machine is large: the makers claim that 400 tons are put through these machines at Mineville, N. Y., in 24 hours.

This separator consists of a round table of brass 3 mm. thick, and 1.45 meters in diameter, which slopes from center to circumference. Beneath this separating surface, which revolves, there is a system of 12 stationary magnets, arranged radially to cover 6/7

of the surface of the table; beneath the sector, representing 1/7 of the area, there is a gap without magnetic attraction. The magnets are of alternate polarity and have their corners beveled to concentrate the lines of force at the periphery, and are spaced 50 mm. apart. Above the table is a series of movable perforated pipes, which deliver a spray of wash water on the ore under separation. The ore is delivered in a stream of water at the center of the table, and spreads out in a layer of decreasing thickness toward the periphery. The magnetic particles are held against the surface of the table and carried by its revolution to the sector where there is no magnet and here washed off. The nonmagnetic particles are washed off the table by the wash water from the pipes. The alternate polarity of the magnets causes the magnetic particles to turn over in passing from one magnet to another, the entrained waste liberated during this process being washed off by the sprays from the pipes, which are hung 40 mm. above the table. The two products are caught in separate launders at the periphery of the table. Magnetic particles are prevented from being washed off the table by the concentration of the magnetic field due to the beveling of the magnets mentioned before. The capacity of the machine is 2 metric tons per hour, at 10 R.P.M.; 150 liters of wash water are used per minute; H.P. is sufficient to operate the moving parts, while the magnets require 8 amperes at 100 volts for excitation.

The construction of this machine is best understood from the accompanying figures. The magnets A and the coils C revolve about the shaft B. The magnet wheels are divided into 21 spokes, the spokes on each side being opposite one another. Between the two halves of the magnet is an annular slot, extending completely around the circle; the walls of this slot are thin sheets of nonmagnetic metal, and this space is filled with water to the height of the axle. The ore is fed by a stream of water at E; the magnetic particles form bridges in the fields between the opposite spokes, and are carried around by the revolution of the magnets. At K a launder is introduced into the slot, receiving the bridges of magnetic particles, which are washed out of the machine through this launder .by a strong jet of water. The magnetic material is washed, and waste particles removed, by sprays of water playing on the bridges across the slot between the time it is lifted above the water level and the time of its encountering the discharge launder. The nonmagnetic particles fall to the bottom of the tank and are discharged at H. A float, J, is connected with the discharge opening, H, by a rod; when the water rises above the proper level, because of the introduction of the

feed, the discharge gate at H is opened and the surplus water, along with the waste, flows from the machine. The capacity of this separator is about 2 metric tons per hour; the magnets take 20 amperes at 110 volts. Nonmagnetic slimes which do not settle readily are drawn off from time to time through the pipe F.

This separator comprises five independent separating zone; which may be employed, if desired, on different ores and with different strengths of field. This machine consists of two concentric brass rings mounted with soft-iron secondary poles attached to a spider which, by revolution about a vertical axis, causes the rings to pass between the poles of five fixed electro-magnets spaced 72 degrees apart. The ore is fed in the annular space between the brass rings at points opposite the primary magnets; the magnetic particles in the ore attach themselves to the secondary magnets, while the nonmagnetic particles fall past them into a tailing chute. As the rotation of the brass rings carries the secondarily induced magnets past the fixed primaries they lose their magnetism and the attracted particles fall, first the feebly magnetic particles, which drop into a middling chute, and finally the strongly magnetic particles which drop into a concentrate chute.

of this machine varies with the size of the material treated: operating on magnetite ore crushed to 1.2 mm. it handles 1 2/3 metric tons per separating zone per hour; arranged for cobbing, it handles 2.5 metric tons per separating zone per hour for sizes up to If ins. The brass rings rotate at a speed of from 5 to 10 R.P.M.

not enough to draw them against the magnets. The falling sheet thus divided is caught in separate chutes or hoppers. The current on the magnets and the distance from the falling ore sheet to the face of the magnet are capable of adjustment to suit different ores.

A single magnet may be employed to effect the separation, or a number of units in series. In the mill at Edison, N. J., two systems were employed, the first to produce a clean tailing product and a second for the cleaning of the concentrate from the first magnets.

The preliminary magnets are arranged as shown in Fig. 13. The ore is fed past each end of the magnets, the magnetic product passing from the machine from each magnet, while the nonmagnetic particles are successively re-treated. This arrangement produces a clean tailing with very little loss in magnetic material. The magnets are 12 ins. long, 4 ins. thick and have a separating face 4 ft. 6 ins. wide. The cores are of cast iron (as the magnets are never saturated) and are wound with No. 4 copper wire. The three magnets are wired in series, and each has a different winding, the upper with the fewest and the lower with the greatest number of turns, giving separating fields of constantly increasing strength in the direction of travel of the ore. The magnets are excited by 15 amperes at 80 volts. The capacity of the series is 16 tons per hour of ore crushed to pass 0.06 in. A second series of magnets is used to re-treat the magnetic product from the above-described machine after drying and recrushing. The arrangement is the same, but the magnets are 8 ins. long, and are wound with No. 6 wire: the capacity is 2.25 tons per hour on material crushed to pass 0.02 in.; tailings from the last magnet are waste. These magnets take 10 amperes at 120 volts.

The cleaning magnets are arranged in a series of five units, and treat the concentrate from the preliminary magnets after the removal of dust. With this machine the object is the production of a clean magnetic product, and the magnets are arranged as shown above to repeatedly re-treat the magnetite, the tailing being discharged after passing each unit. The magnets are 4 ins. long, 2 ins. thick and have a separating face 4 ft. 6 ins. wide. They all have the same winding of No. 6 wire, are connected in series and take 17 amperes at 100 volts. The tailing from the upper magnet in this series is run to waste, while the tailing from the four lower magnets is regarded as middling and sent back for re- treatment. The capacity of this machine is about 0.9 ton per hour.

This machine consists of a belt 7 ft. wide which travels over two pulleys revolving about horizontal axes in the same vertical plane. Behind the side of the belt which travels upward are placed several electro-magnets staggered across the belt, adjacent magnets being of opposite polarity. The ore is fed against the belt opposite the lowest magnet, the magnetic material adheres to the belt and is carried upward and across it as a result of the arrangement of the poles of the magnets; the nonmagnetic particles fall from the belt. The material fed is in a fine state of division and forms tufts on the surface of the belt which turn over and over in their passage across and up the belt, liberating any particles of entrained waste. The upper magnet extends

further toward the edge of the belt than the lower magnets, and the magnetic particles are dropped from it into a series of small buckets riveted to the edge of the belt, and so discharged from the machine. This separator is designed for the removal of non-magnetic particles from a finely divided feed.

This machine is used for cobbing ores which are not necessarily dry; the ore fed is coarse (1 ins.) and the separator puts through a large tonnage with the idea of making a clean concentrate of the pure magnetite pieces, while the tailing is re-treated on other separators after crushing. The separator consists of a drum with nonmagnetic surface which revolves about a composite magnet in the form of a sector of a circle. The attraction is exerted by 16 electro-magnets attached to a spider and mounted

on the shaft of the drum. The magnets are stationary and cover a little more than 180 degrees of the circumference of the drum. They are of alternate polarity, which causes the ore to turn over as it is carried past each of the 16 poles by the revolution of the drum. This turning over permits the nonmagnetic particles to drop off the drum into the tailing hopper. The ore is fed near the top of the drum, and the strongly magnetic pieces are carried past the tailing hopper and thrown off by centrifugal force as they pass beyond the influence of the last magnet, falling into a concentrate chute. The amperage is regulated so as to pick out the pure pieces of mineral only, allowing composite pieces of ore and waste to go into the tailing to be separated after crushing.

This machine consists of a drum made up of alternately magnetic and nonmagnetic bars, which revolves about a horizontal axis and encloses a stationary magnet. The stationary magnet is cylindrical in form and is placed eccentrically within the revolving drum; it carries four circular projections, or ridges, between which are wound the exciting coils, so connected that adjacent projections have opposite polarity. The surface of the drum is made up of soft iron bars with nonmagnetic spaces between them usually filled with strips of wood. The bars have projections from the inner surface of the drum which engage the projections from the magnet, making them practically prolongations of the poles of

the magnet. The projections on alternate bars engage alternately the north and south poles of the stationary magnet, giving adjacent bars opposite polarity. The projections from the magnet are cut away on one side of a vertical diameter of the drum. The ore is fed at the top of the drum and is carried forward by its revolution; the magnetic pieces are held by the magnetic bars until the vertical diameter is passed, when they fall into a hopper upon the bars becoming demagnetized. The waste falls into a hopper in front on the drum. This machine is designed to treat lump ores which need not necessarily be dry. It is made in two sizes: the larger size is capable of separating 4-in. lumps, is 27 ins. in diameter and 24 ins. across the face, takes 15 amperes at 110 volts and has a capacity of from 5 to 7 tons per hour. A smaller size has a capacity of 3 tons per hour on ore 1.5 ins. maximum size.

This is a modification of the machine above described. The distance between the ribs making up the surface of the drum of this separator is varied to suit the size of the ore to be treated. For the finer sizes, from 1/8 to 1 1/8 ins., the drum is covered with a sheath of German silver. For treating coarse ores the drum is made in diameters from 2 ft. 10 ins. to 3 ft. 4 ins.; the length

of the drum face is 2 ft. Recently some of these machines have been built with twice this width and divided into two sections, one side for coarse and the other for fine material. The drums make from 16 to 20 revolutions per minute; the electro-magnet requires from 15 to 20 amperes at 110 volts for excitation. The capacity of this separator varies from 5 to 10 tons of crude ore per hour.

resembles the Wenstrom machine, the drum being made up of ribs alternately iron and brass. The former are in. wide and the latter 3/16 in. wide. The drum is operated at a speed of 30 revolutions per minute.

This separator consists of an inclined shaking conveyor which serves to carry the material to be separated beneath two wheels, each studded with secondarily induced magnets and revolving about vertical axes. The ore is fed from a hopper at the head of the inclined conveyor, and is transported by the shaking movement through four zones of separation, due to the magnet wheels. The first magnet encountered by the ore carries the less current and separates the strongly magnetic particles only; the second magnet carries a greater current and separates a middling product; the nonmagnetic tailing passes off the end of the shaking conveyor.

The conveyor is a tray made up of a sheet of 3/16 in. steel covered with asbestos and mounted upon hangers. A shaking movement is imparted to the conveyor by an eccentric, the movement being upward at the feed end and also in the direction of the travel of the ore. The usual speed is 440 strokes per minute. While passing over this conveyor the ore is kept constantly in agitation, thus lessening the chance of entrainment. The conveyor is 18 ins. wide and 7 ft. long, and may be raised or lowered by means of hand wheels on the hangers, thereby altering its distance from the magnets. By raising one end only, a different and gradually increasing distance from the plate to the magnet wheels may be obtained at each of the four zones of separation. This separator is also built with a conveyor belt in the place of the shaking conveyor.

The primary magnets are fixed, and consist of two steel cores, which carry the windings and connect the pole pieces. These pole pieces are made in the form of circular arcs to correspond with the secondary magnets revolving below. The secondary magnets are made of laminated steel and are disposed around the periphery of a bronze carrying wheel 30 ins. in diameter; they project as cylindrical knobs about 1 in. below the carrier, and their upper ends are U-shaped to engage closely, but not to touch, the pole pieces of the primary magnets. The magnetic circuit is completed through the steel plate beneath the asbestos covering of the conveyor. As the individual secondarily-induced magnets are carried by the revolution of the carrying wheel beyond the fields of the primaries, they lose their magnetism and allow the attracted particles to drop off. These magnets reverse their polarity before entering the field of the opposite pole of the primary, causing a thorough discharge of their burden of magnetic particles. Troughs are provided to carry away the magnetic particles dropped, and may be so arranged as to deliver four distinct products, if it is desired.

In operation, a variety of adjustments may be made, to suit different ores, by altering the amperage on the primary magnets, by changing the distance from the conveyor to the secondary magnets, and by altering the inclination of the conveyor. The capacity of the machine may be taken at 1 ton per hour of properly roasted blende-pyrite concentrate. About one mechanical horse power is required for operation, and from to 2 electrical horse power for excitation.

In this a broad conveyor feed belt transports the ore to be separated beneath highly magnetized rollers. These rollers, which revolve in the same direction as the travel of the belt beneath them, pick up the magnetic particles from the ore stream and deposit them on cross belts which remove them to one side. At the end of each cross belt is another magnet which acts upon the magnetic particles as they are thrown off the cross belt, diverting them into suitable receptacles, according to their permeabilities, giving a double separation of the magnetic particles. These separators may be operated at high speed and are said to have a large capacity on strongly magnetic ore or artificial magnetite.

This machine comprises a conveyor belt which serves to transport the material to be separated beneath two cylindrical electromagnets which revolve about vertical axes at a height of approximately 1 in. above the belt. The first magnet encountered by the ore, usually called the rougher magnet, is the weaker of the two and attracts the more strongly magnetic particles of the ore only; the second, or cleaner, magnet carries a higher amperage on a greater number of turns, and removes such magnetic particles as were not attracted by the first magnet, making a middling product; the nonmagnetic particles pass off the end of the belt. This machine is made in two sizes, with 12-in. and 21-in. belts respectively; a description of the 21-in. belt machine will serve for both.

The belt of seamless rubber on a heavy canvas base is carried on two 18-in. pulleys and driven from a line shaft through the pulley at the feed end; provision for taking up stretch in the belt is made by capstan bolts working against the sliding bearing of the pulley at the discharge end. The belt is kept level beneath the magnets by three liner pulleys which are capable of adjustment to permit the regulation of the distance between the magnets and the surface of the ore stream.

The magnets are cylinders 26.5 ins. in diameter, the rougher of cast iron and the cleaner of cast steel and are set to overhang the belt at one side. An annular space in. in width is turned out of the bottom of the magnets 1 3/8 ins. from the periphery and is filled with spelter; the magnetic circuit is from the outside shell across the spelter gap to the inner core of the magnet about which the coils are wound. The magnetic particles are attracted and form a bridge across the spelter ring, and, by the revolution of the magnets, are carried to one side where they are scraped off by a brass scraper.

The normal speed of the conveyor belt when treating artificial magnetite is 100 feet per minute, and the speed of the magnets is 40 R.P.M. At this speed the operator is capable of treating 1 ton per hour of properly roasted blende-pyrite concentrate of average grade and crushed to pass 4 mesh. The capacity of the 12-in. machine is about one half that amount. The amperage employed varies with the ore and the quality of the roast from to 2 amperes on the rougher magnet and from 3.5 to 10 amperes on the cleaner magnet.

This separator is built to separate wet concentrates and finely divided material. It is said not to require a preliminary classification of the feed, and to work well on very finely divided ore. This machine consists of a number of electro-magnets mounted on a spider which revolves in a tank partly filled with water. The ends of the revolving magnets are connected by the shaft with the walls of the tank, which form the opposite poles; the separation is accomplished in this space, between the ends of the moving magnets and the cylindrical wall of the tank. The ore is fed into the machine at one side, the moving magnets pick up the magnetic particles and carry them above the water level, where they are washed off into a launder by a strong jet of water: the non- magnetic particles are drawn off through the bottom of the tank. The movement of the magnets through the water stirs up the ore thoroughly and permits a thorough separation. The machine operates on a 0.5 H.P. and requires 10 amperes for excitation of the magnets.

In general principle this machine resembles the Primosigh separator for dry ores described in the following chapter. The material to be separated, in a fine state of division, is fed in suspension in a stream of water into the grooves at the top of the magnet

cylinder, which is suspended above a spitzkasten so as to be immersed in water during a part of its revolution. The nonmagnetic particles drop away from the pole pieces as soon as they reach the water, while the magnetic particles are carried above the surface of the water and removed by a series of secondarily induced magnet points as in the dry separator. This machine is adapted to the treatment of fine material. Upon a feed ranging from 0.25 mm. down to dust the capacity for a machine with four separating grooves is 0.4 metric ton per hour. Twelve amperes at 80 volts are required for excitation, and H.P. for revolution.

This separator is designed to treat slime. It consists of a round table with flat surface which rotates above a series of fixed electro-magnets. The magnetic particles are held against the surface of the table by the magnets beneath, while the nonmagnetic

This is similar to the above-described separator for the treatment of dry ores. The drum revolves partly in water, and the material to be separated is fed against it, near the lower vertical diameter. The nonmagnetic particles sink to the bottom while the magnetic particles are carried farther by the revolution of the drum and washed off by a stream of water. A stream of wash water is directed against the magnetic particles while held against the drum, to remove nonmagnetic dust and entrained particles. The drum is protected by a water-tight mantle of sheet copper. The capacity of these machines varies, with the kind of ore and the size treated, from 500 to 4000 pounds per hour.

ing downward close to the casting on the side of the ore feed. This apparatus is set vertically in a tank filled with water to a point above the top of the magnets. The ore, best below 30 mesh, as the machine is intended to treat fine material, is fed at the top of the belt in a stream of water; the nonmagnetic particles fall and are carried straight down by the flow of water, while the magnetic particles, held against the belt by the magnets, are carried around the lower pulley and dropped into a separate hopper. The construction is best understood from the above figure where A is the point at which the ore is fed, in suspension in water; B, the belt which conveys the magnetic particles past the magnets; c-c, the pulleys about which the belt runs; E, the concentrate hopper; F, the concentrate discharge; G, the tailing hopper; H, the tailing discharge. The actual separation of the non-magnetic particles from the magnetic takes place at the end of the shield shown close to and opposite the lowest magnet. The feed and discharge of both concentrate and tailing are continuous. The belt is 2 ft. 6 ins. wide. The capacity of the machine reaches 35 tons per 24 hours.

In this machine a conveyor belt serves to carry the ore beneath an electro-magnet whose poles extend across, and just above, the conveyor belt. A cross belt running beneath the poles carries the magnetic particles attracted against it to one side, where they are discharged into a chute. The nonmagnetic particles are discharged off the end of the conveyor belt.

This machine consists of a drum whose face is made up of alternately magnetic and nonmagnetic bars, revolving about fixed internal electro-magnets. The primary magnets are placed to cover a part of the lower diameter of the drum; the secondary magnets, carried on the face of the drum, become magnetized by induction while passing the primaries, and pick up the magnetic particles from the stream of ore which is fed beneath the drum. The magnetic particles drop off the drum as the secondary mag- nets become demagnetized on passing out of the field of the primaries. The whole machine is covered with a dust-tight hood. The capacity varies, with the kind of ore and the size to which it is reduced, from 700 to 3000 pounds per hour.

below the take-off belt and at right angles to it, each feed belt supplying a magnet. The poles of the horseshoe magnets are bent in toward each other, giving a concentrated field at right angles to the feed belts. The magnets are fitted with an iron projection extending a few inches beyond the ends of the poles in the direction of travel of the take-off belt, permitting the magnetic particles to be carried to one side and dropped past the feed belts into separate hoppers. Each magnet is fed with a different size of ore

except two magnets, which both treat ore passing through a 1 mm. screen, as this size preponderates. Mounted on the separator frame are shaking screens, which deliver sized products into separate hoppers, which in turn deliver on to the feed belts. The feed belts are 12 ins. wide and travel 1.5 ft. per second. The height between these belts and the magnets is capable of adjustment through the small guide rollers shown just below the magnets. The distance through which the magnetic particles are lifted varies from 30 to 40 mm. Each magnet requires 2 amperes at 50 volts. The capacity of the apparatus is slightly over 1 metric ton per hour.

This machine comprises a shaking conveyor which feeds the material to be separated from a hopper upon a conveyor belt, which in turn presents it to a magnetic drum, fitted with a belt serving to remove the particles attracted. The magnetic drum is

composed of a series of composite pole pieces which dovetail into one another in a manner best understood from an inspection of the accompanying illustrations. The poles are insulated by a filling of zinc, the whole forming a smooth surface. The exciting coils are placed within the drum, connections with the dynamo being made through disks which dip into cups containing mercury. This machine, fitted with a belt 16 ins. wide, treats about 500 kgm. of calcined limonite-calamine ore per hour. The magnets require 1.5 amperes at 110 volts for excitation.

The deviation of magnetic particles from a falling sheet of finely divided ore is the principle upon which this separator operates. The attraction is exerted by six horseshoe magnets separated by bronze rings. These magnets, which are arranged horizontally, are enclosed in a brass cylinder which revolves at from 8 to 10 R.P.M. The ore is fed in a thin sheet at a distance of from 5 to 25 mm. from the brass cylinder. The magnetic particles are drawn toward the magnets but are prevented from adhering to them by the brass cylinder; the magnetic and nonmagnetic products are divided by an adjustable diaphragm and fall into separate hoppers. The capacity of the machine is 500 kgm. per hour. The entire apparatus is enclosed in a sheet-iron housing to prevent air currents, which would interfere with the separation. The machine treats material passing a screen with 1.5 mm. holes

the drum into a hopper, while the magnetic particles are held against the surface of the drum by the magnets and are carried, by its revolution over the top of the drum to fall into a separate hopper. The drum makes 36 R.P.M. 6 to 7 amperes at 65 volts are required for excitation, and 1/8H.P. for revolution.

This consists of an annular magnet suspended in a horizontal plane within a circular casing. The ore is guided to the magnet by a conical shield, and, passing between the magnet and the casing, the magnetic particles are drawn inward, while the nonmagnetic particles fall past the magnet unaffected. The two products are gathered in two concentric inverted cones, the inner receiving the magnetic portion and delivering it from the separator by means of a spout through the lower, or outer, cone. The separator contains no moving parts. In lieu of an air gap between poles the separation is effected in a zone of dispersion caused by

a narrowing of the enclosing casing, which induces a magnetic resistance. The operation of the separator is best understood by inspection of the figure given above. The magnetic ring has a diameter of 40 cm., or a separating periphery of about 1.25 meters. The separator is said to have a capacity of 1 metric ton per hour.

This separator consists of a stationary primary magnet between the poles of which a belt, which is studded with small secondary magnets, is caused to travel. The construction is made clear in the accompanying illustration. The ore is fed from a

hopper upon a reciprocating feed plate, which in turn delivers it upon a reciprocating conveyor plate; this conveyor plate brings the ore close to the belt carrying the secondary magnets; the plate and belt gradually approach each other, causing the ore particles to move in a magnetic field of constantly increasing strength. The magnetic particles are picked up by the secondary magnets and held until carried past the primary magnet, when they are gradually dropped off in inverse order to their magnetic permeabilities by the gradually decreasing strength of the secondary magnets. The nonmagnetic material falls from the end of the conveyor plate into a separate hopper. The upper pole of the primary magnet is beveled, coming to an edge at its lower end, thus giving a concentrated field at this point: the lower pole is rounded, and being movable, an adjustment of the concentration of the magnetic field is obtainable. The secondary magnets are soft-steel rivets, with serrated washers on the lower side of the belt, there are about 200 of these rivets per square foot of belt,

more about magnetic separation

Last month, we wrote about how magnets are assembled for magnetic separation applications attracting iron, steel, or other ferromagnetic bits to get contaminants out of other materials. It was a great example of some specific ways that magnets are selected and assembled for this task.

What if there was a way to use magnets to separate metals that are NOT attracted to magnets? If we could separate aluminum cans (which magnets dont stick to) from other, non-metallic trash, would that be amazing?

This demonstration is fairly straightforward. We constructed a conveyor belt that has a roller covered with magnets. The magnets are arranged with alternating poles facing out, which provides a strong magnetic hold.

The results are pretty much what you would expect. The stuff that is not attracted to magnets just falls straight down. The ferromagnetic bits that are attracted to magnets stay stuck to the conveyor belt a little longer, and are dropped a bit further back.

The answer lies with Eddy Currents. If you move a magnet near a piece of conductive metal, the moving magnetic field induces currents in the metal. The spinning currents act like little magnets, making a repelling force between the magnet and the metal.

In that earlier article, we showed a few classic demonstrations of this phenomenon, such as a magnet falling slowly through a tube or sliding slowly down an aluminum surface. If we have enough magnetic field strength and relative speed between the magnets and the metal, the magnets exert a force on the metal.

For a demonstration, we'll use another conveyor belt arrangement. The key to eddy current separation is to get the magnets moving much faster than the material on the conveyor belt. We need to get the magnets moving a lot faster than the stuff were separating.

We put a stationary tube around the spinning magnets, and slid a conveyor belt slowly over it. Inside the tube, we spin the magnets around at great speed. The quickly moving and changing magnetic fields provide a force in bits of aluminum thanks to eddy currents. This gives these materials an extra nudge off the conveyor belt, throwing them off rather than just dropping them.

Thats really a general question looking for a specific answer. It depends! The magnets you choose depend on a wide number of variables, including the design of your machine, conveyor belt, desired strength, distance from the magnets to the materials, etc.

We used some BX884DCS magnets for our iron separator. Our Countersunk Magnets are popular for this sort of thing, since they are easy to assemble. Most of the actual, industrial separators weve seen use much larger magnets like the 2" x 1" x 1/2" thick BY0X08DCS. We chose smaller ones because it was simpler for our scaled-down model.

We used 2" x 3/8" x 1/4" thick BY064 plain blocks for the Eddy Current Separator shown in the second video. It was a good size for our scale, and they worked well. We actually chose these specific magnets because we had a small stack set aside that had scratched plating. Other similar block magnet sizes would have worked as well.

7 factors affecting froth flotation process - jxsc machine

The full name of the flotation is called froth flotation. It is the process of selecting minerals from the pulp by means of the buoyancy of the bubbles, depending on the difference in the surface properties of the various minerals. Where to buy flotation machines?

The specific process of flotation is to add various flotation reagents to a certain concentration of slurry, and a large number of diffuse bubbles are generated by stirring and aeration in the flotation machine. At this time, the suspended ore collides with the bubbles, and some of The floatable ore particles adhere to the bubbles, and float up to the surface of the ore to form a foam product, which is the concentrate; the non-floating mineral remains in the slurry and becomes the tailings. Thereby, achieve the purpose of mineral sorting.

Froth Flotation machine plays an indispensable role in the mineral beneficiation process, flotation is susceptible to a number of factors during the process, including grinding fineness, slurry concentration, pulp pH, pharmaceutical system, aeration and agitation, flotation time, water quality and other process factors. The factors that affect the flotation process are detailed below.

Both large ore particles (larger than 0.1mm) and small ore particles (less than 0.006mm) affect flotation efficiency and mineral recovery. In the case of flotation coarse particles, due to the heavyweight, it is not easy to suspend in the flotation machine, and the chance of collision with the bubbles is reduced. Further, after the coarse particles adhere to the air bubbles, they are easily detached from the air bubbles due to the large dropout force. Therefore, the coarse particles have a poor flotation effect under the general process conditions.

During the fine particles flotation separation process, the fine particles are small in volume and the possibility of collision with the bubbles is small. The fine grain quality is small, and when it collides with the bubble, it is difficult to overcome the resistance of the hydration layer between the ore particle and the bubble, and it is difficult to adhere to the bubble.

The content of the coarse-grained monomer must be less than the upper limit of the particle size of the mineral flotation. At present, the upper limit of flotation particle size is generally 0.25-0.3 mm for sulfide minerals; 0.5-1 mm for natural sulfur; and the upper limit of particle size for coal is 1-2 mm.3.Avoid muddy as much as possible. When the flotation particle size is less than 0.01 mm, the flotation index will decay significantly.

The most appropriate grinding fineness must be determined by testing and reference to production practice data. For some ores, the stage grinding and stage selection process are often used to avoid over-grinding of the ore, so that the dissociated ore particles are selected in time.

If the froth machine contains much ore slurry, it will bring a series of adverse effects on flotation cells mineral processing. The main influences are as follows 1 Easy to be mixed in the foam product, so that the concentrate grade is reduced. 2 Easy to cover the coarse grain surface, affecting the flotation of coarse particles. 3 Adsorption of a large number of agents, increase drug consumption. 4 The pulp is sticky and the aeration conditions are deteriorated.

The type and quantity of the agent added during the flotation process, the dosing place and the dosing method are collectively referred to as the drug system, also known as the prescription. It has a major impact on flotation indicators.

In the ore dressing, it is necessary to pass the ore selectivity test in order to determine the type and quantity of the agent, and in practice, the number, location and mode of dosing should be constantly revised and improved.

In addition to oxygen, nitrogen and inert gases, there are carbon dioxide and water vapor in the air. The gas has a selective effect on the surface of the mineral, oxygen is the most important factor affecting the surface of minerals. Oxygen is beneficial to the hydrophobicity of sulphide ores/ sulfine flotation, however, if the action time is too long, the mineral surface will return to hydrophilicity. When the gas adsorption conditions are appropriate, the mineral surface will be drained, the flotation mineral processing can be done even without a flotation agent. The Galena mine can only float up with the action of xanthate through the initial action of oxygen.

Stirring the slurry can promote the suspension of the ore particles and evenly disperse in the tank, thus promote the good dispersion of the air and make it evenly distributed in the tank, further can promote the enhanced dissolution of air in the high-pressure area of the tank, and strengthen the precipitation in the low-pressure area. Enhanced aeration and agitation are advantageous for flotation separation, but not excessively, as excessive aeration and agitation can have the following disadvantages: (1) Promoted the merger of bubbles (2) Reduced concentrate quality (3) Increased power consumption (4) Increased wear of various parts of the flotation machine (5) The volume of the slurry in the tank is reduced (this is because the volume of the tank is increased by the portion occupied by the bubble) (6) Excessive agitation may also cause the ore particles attached to the bubbles to fall off. The optimum amount of aeration and agitation in production should be determined by experimentation depending on the type and structural characteristics of the flotation machine.

Inflation and agitation are carried out simultaneous in the flotation machine. Strengthening them is beneficial to increase the flotation index, but if it is determined too much, it will cause shortcomings such as bubble merger, degraded quality, increased electric energy consumption, and mechanical wear. Therefore, aeration and agitation must be appropriate.

The slurry concentration can affect the following technical and economic indicators: (1) Recovery rate. When the slurry concentration is small, the recovery rate is low. As the concentration of the slurry increases, the recovery rate also increases, but the recovery rate exceeds the limit. The main reason is that the concentration is too high, which destroys the aeration condition of the flotation machine. (2) Quality of concentrates. The general rule is that the quality of the concentrate is higher in the flotation of the leaner slurry, and the quality of the concentrate is reduced in the flotation of the richer slurry. (3) Consumption of pharmaceuticals. When the slurry is thicker, the amount of treatment per ton of ore is less, and when the concentration of the slurry is thinner, the amount of treatment per ton of ore is increased. (4) The production capacity of the flotation equipment. As the concentration of the slurry increases, the production capacity of the froth flotation machine calculated according to the treatment amount also increases. (5) Water and electricity consumption. The thicker the pulp, the smaller the water and electricity consumption per ton of ore processed. In short, when the concentration of the slurry is thick, it is beneficial to the flotation process. However, if the slurry and bubbles do not flow freely, the aeration will deteriorate, thereby reducing the quality and recovery. In this case, the various ore sections of the flotation should determine the appropriate concentration of the slurry according to the nature of the ore and relevant technical requirements.

The most suitable ore pulp concentration during the flotation process is related to the ore property and the flotation processing conditions. The general rules as flow: (1) Pulp Density. The mineral with large flotation density uses a thicker slurry, while the mineral with a small flotation density uses a thinner slurry. Flotation of coarse-grained materials with thicker slurry, flotation of fine-grained and muddy materials with thinner ore. (2) Pulp PH Value. The pH of the pulp refers to the concentration of OH and H+ in the slurry, which is generally expressed by the PH value. Various minerals have a floating and non-floating pH when using different flotation agents for flotation, The pH of the critical pH. By controlling the critical pH, it is possible to control the effective sorting of various minerals. Therefore, controlling the pH value of the slurry is one of the important measures to control the flotation process. (3) Flotation Time. The flotation time directly affects the quality of the indicator. The time is too long, the grade of the concentrate is reduced; the time is too short and the grade of the tailings is increased. Therefore, the flotation time required for various Minerals must be determined by experimentation. (4) Water Quality. Floating water should not contain a large number of suspended particulates, nor can it contains soluble substances and various microorganisms that may interact with minerals or flotation reagents. This problem should be specially noticed when using backwater, pit water, and lake water. (5) Pulp Temperature. Flotation is generally carried out at room temperature, but sometimes it is necessary to warm the slurry in order to obtain a good sorting effect. The specific heating or not needs to be determined according to the actual situation. If it is heated, it is best to adapt to local conditions and use waste heat and exhaust gas as much as possible.

The main effects of pulp quality score on froth flotation process in metallurgy are as follows: (1) Recovery rate. Within a certain range, when the pulp mass fraction is low, the recovery rate is low; the pulp mass fraction is increased, and the recovery rate is correspondingly increased. However, the mass fraction of the slurry should not be too large. If it is too large, the flotation machine is difficult to inflate normally in the slurry, which in turn reduces the recovery rate.

(2) Concentrate grade. The general rule is that the concentrate grade is higher when ore flotation is carried out in a leaner slurry, while the concentrate grade is reduced when it is floated in a thicker slurry.

(3) The dosage of the agent. The flotation agent should maintain a certain mass fraction in the pulp to have a good flotation effect. When the pulp is thicker, the mass fraction of the medicament is correspondingly increased, that is, the required medicament mass fraction can be achieved with fewer chemicals, and the amount of medicament per tan ore is correspondingly reduced. Conversely, when the pulp is thinner, the amount of the agent increases.

Thats all 7 main variables affecting froth flotation. Contact us to know more info about industrial gold mining equipment, get free froth flotation PDF, flotation process flow chart, and related industry cases of gold froth flotation, zinc froth flotation, copper flotation, ore flotation.

Since the content of useful components in the ore that needs flotation treatment is getting lower and lower, the particle size of the impregnation is getting finer and finer, and the composition is more and more complicated and difficult to separate. Therefore, how to design an efficient mineral flotation flow is of the utmost importance.

magnetic ore separator

After considerable experience in connection with the magnetic iron-ores at the South, especially in the Cranberry district of western North Carolina and eastern Tennessee, the writer was led into a thorough investigation of the magnetic separation of iron-ores, and, from this investigation, has gradually been developed a separating machine which it is the purpose of this paper to explain.

Numerous United States patents have been issued upon machines for magnetic separation. Since the original patents, it is not possible today to establish broad claims upon the principles of electro-magnets as applied in such machines. Among these inventions there are certain types of separators which have very marked practical advantages over the others; and these successful machines, while varying radically from each other in their proportions and arrangements, are all based upon a principle originally explained in a patent which was granted, and which has now expired by limitation.

The problem of practically separating iron-ores, as found in the mines, is very different from the separation of a purely magnetic substance from a purely non-magnetic one, since the crystals of magnetite, scattered through the ore-bearing rock, and sometimes collected in masses, are of very different sizes. The average size of the particles may be definitely ascertained for each mine, and the crushing- and screening-machinery may be adapted thereto, but there will still be a large percentage of very fine crystals which, in the crushing for the average, will not be broken apart from the gangue. If these mixed particles are thrown into the heads they carry gangue with them, and if thrown into the tails they occasion a loss of iron-ore. There are two methods for preventing such loss. One is, to crush all the material to the size of the finest particles, which means, of course, a large crushing-plant, heavy wear and tear, and excessive cost for repairs, and the production of only a very fine-grained concentrate which our blast-furnace managers, to say the least, do not ardently desire. The other, and only practical method, is to crush at first to a comparatively coarse size, determined by the character of the material, and to separate immediately upon a machine which has a power of selection, and which will throw off a first-grade of tails, containing practically no magnetite, then a second tails or middlings, with iron in the mixed particles, then a third (and if necessary, a fourth, etc.) division, and finally, a practically pure magnetite as heads. The first tails go to the dump, the heads, comparatively coarse, are sent at once to the bins or cars, and the second and third or other tails, which may amount, perhaps, to one-fourth of the crude material, are re-treated on a second separator, and such portions of them as may require it, are crushed sufficiently fine to break the magnetite from the gangue. The fine crushing of three- fourths of the product is thus saved, and the cost and wear are correspondingly reduced, while the concentrates contain mainly coarse particles. These facts have been appreciated for many years by those skilled in the art; but the mechanical and electrical difficulties in the designing of practical machines were deemed by many to be insurmountable. There are, however, now on the market, as already remarked, a number of forms of separators which act on this principle, and are excellent machines, each protected by special patents.

The machine which is the subject of this paper is one of these. In designing it we have endeavored to keep in mind the essential requirements for machinery subject to rough usage, viz. (in addition to efficiency and economy of operation) durability, simplicity of design, and convenience for replacing quickly by ordinary unskilled labor any disabled partsconsiderations which apply as well to magnetic separators as to other machinery connected with mining.

This machine has grown out of the original Lovett-Finney magnetic separator, which has been running successfully at Weldon, N. J., for eighteen months or more. We have retained the features of simplicity and low cost for repairs which distinguished that apparatus, but have changed the form and the electrical arrangement, and have added other magnetic parts which essentially modify the action of the separator and the character of its products.

The present form of the magnetic wheel is a solid soft-iron roll of small diameter (4 inches or less), and of any desired length (usually 3 feet), in which two helical grooves of about 1 square inch section are cut. In these are wound coils of continuous copper wire or ribbon. There being two spiral grooves (constituting, in fact, simply a double-threaded screw), the wire carries the electric current in each groove in the opposite direction from that of the current in the adjoining groove, so that a magnetic circuit is set up which converts the screw thread into continuous helical poles of opposite polarity, and forms, with a minimum amount of iron, copper, and cost of manufacture, a magnet of extraordinary strength, with a continuous field of magnetic force all over its circumference. A thin, drawn-brass tube is slipped over this roll, protecting it from injury, without impairing its properties as a magnetic wheel, equally efficient per square inch of surface whatever the length of the roll may be.

In the Chase separator, as shown in Figs. 1 and 2, there are three of these magnetic rolls, A, B, and C, Fig. 1. The function of the first roll is to separate a wholly non-magnetic grade of tails from the remainder of the material treated. As the crude material is fed upon a belt, which approaches the wheel horizontally, the necessary consequence is, that every particle of magnetic oxide of iron comes immediately within the scope of the magnetic field, and cannot escape until carried by the rotation of the roll around to its under side, while the non magnetic tails fly off tangentially.

The pure magnetite, the mixed particles, and a considerable amount of non-magnetic dust, all cling together to the belt against the under side of the roll, and are passed on by the movement of the belt to the first of a series of horizontal magnetic poles. These are consequent poles, developed by winding a soft iron yoke alternately in opposite directions, and inserting between these windings soft iron bars to form the poles. A tumbling motion is immediately set up in the mass; the middlings drop quickly into their receptacle; the fine dust continues further, but falls also into its receptacle, while the pure magnetite passes along under all the poles and is delivered by the last of these to the second magnetic wheel, B, which whisks the magnetic particles around the sharp corner, freeing them from the last grains of dust by this movement, together with the action of a blast of air or of water from the pipe P. The second wheel, B, delivers the magnetite to the third or picker-wheel, C, over which runs the second belt, which carries the magnetite to any desired point. The letters in Figs. 1 and 2, besides A, B, C and P, already mentioned, indicate the following parts: D, driving- pulley ; E, tightener-pulley; F, non-magnetic rolls, delivering heads; H, feed-hopper and feed-wheel; O, overflow.

The separator is simple in its construction and cheap to build. Its wearing parts consist of the bearings for the shafts, and the cheap , cotton-duck belt, which receives all the wear from the ore, enduring,

by reason of its softness, as wax does before the sand blast, the blows which would cut rapidly into a harder and stiffer material. These belts have been in use for eighteen months upon the separator at the Weldon mine, in New Jersey, and have demonstrated their durability under these conditions.

The merit of this design is mainly in the comparatively small rolls and the short distances between the magnetic poles, which are never increased, however wide and correspondingly capacious the machine may be. The winding of the magnetic rolls in double spiral with continuous spiral poles gives a magnetic field of equal efficiency whatever the length or diameter of the rolls, and the winding of the intermediate magnet is such that it is exactly as efficient per square inch of surface whatever the width of the machine may be. There is, therefore, no limit to the width of the machines, except such as may be set by mechanical considerations.

The length of the separator depends entirely upon the length of the intermediate magnet, which decides the number of tumbles of the stuff, and thereby the quality of the concentrates. This may vary with different ores and degrees of fineness of crushing.

Very interesting facts in connection with electro-magnets of these irregular forms have been brought out in our experiments; and as the matter is one of considerable importance, involving the substitution of another unit of measurement in place of that now in general theoretical use, I feel justified in going over ground already familiar to many. As we all know, an electric current, passing along a wire, creates around that wire, through the air, in planes at right angles to the direction of the wire, a magnetic current, or series of magnetic currents, the quantity of which depends upon the quantity of the electric current. If a bundle of wires be used, the quantity of the magnetic current round about the bundle is proportional to the total amperes of the electric current flowing through the wires; and, taking a unit width of this magnetic circuit (say one inch, or one centimeter), the total magnetic flux through a cross-section of this width will be measured exactly by the total amperage in the bundle of wires; i.e., the number of wires times the amperes in each. If this magnetic current flowing round about this bundle of wires be allowed to pass through soft iron, it becomes vastly increased, the soft iron acting as a good conductor for the lines of force. This increase is represented in theoretical calculations by a constant , which expresses the relative conductivity of iron and air for magnetic lines of force. This constant varies with the quality of the iron, growing less with harder irons, especially with the increase of carbon and manganese, and also less as the iron in question approaches its point of saturation, by which is meant the maximum number of lines of force that can be driven through a unit section of it. In nearly all electrical winding today the cores of soft iron are of circular section, and the wire is in continuous turns about the core, so that the term ampere-turns has come to be accepted as a reliable measure of the magneto-motive force, and hence of the number of lines of force passing through the core.

The design of irregular forms of magnets like the H-section and spirally-wound wheel, already described, has compelled us to look for another basis of measurement, as ampere-turn is not applicable to the spiral winding; and we have thus been led to see that too much emphasis has been laid upon the ampere-turn in theoretical laws and formulae, and that the term turn has received, in this connection, a special significance which it should by no means have. There is absolutely no advantage in a completed circle over the same length of straight wire for the creation of magneto-motive force, and therefore a turn merely represents a certain length of wire. It is true that the total turns multiplied by the amperes passing in each wire gives the total amperes at work upon the magnet, and this is properly a measure of the magneto-motive force which compels the magnetic current to flow through the iron from one pole to the other, and return through the air outside the coil of wire. The quantity of the magnetic current (technically, the magnetic flux ) depends also upon the magnetic resistance of the circuit, which varies directly as the length of the circuit, and inversely as its cross-section. It is evident that the circle is the best form of section for a core, as it gives the greatest area for a given periphery, and therefore the least magnetic resistance for a given length of wire, of all sectional forms. So long as we are considering a core of circular section, the use of ampere-turns is correct, as the outer turns about make up for their increased distance from the iron, by their increased length of circuit. This fact in itself shows that it is the length of the wire, together with its nearness to the iron core, which is of real importance, and not at all the idea of a complete turn. When we consider our spirally-wound magnet, with its continuous helical poles, which are induced only by straight wires on one side carrying electric current in one direction, and by straight wires on . the other side carrying current in the opposite direction, we are forced to drop the term turns out of sight entirely, and use only the total length of wire in a unit-length of coil, which gives, when multiplied by the amperage of the electric current, a proper measure of the magneto-motive force generated in a unit-length of the core beneath measured in the direction that the wires run. The magneto-motive force divided by the magnetic resistance, gives the magnetic flux or total number of lines of force, and thus practically the strength of the magnet under consideration. The point of all this extended explanation is, that for ampere-turn the terms ampere- inch and ampere-centimeter should be substituted, inasmuch as the latter terms are applicable to all forms of magnet coils, while the former is only applicable to a certain special case.

I have noticed this point at some length because, in designing machines involving magnets of irregular forms, one may be thrown off the track by reason of the circumstance that all the theoretical teaching, including the books upon the subject, has proceeded from the study of electro-magnets with cores of circular, or nearly circular, section ; and, therefore, all measurements, laws, and formulae have been based upon the ampere-turn, which we have found to be, for the conditions of our irregularly formed magnets, radically wrong.

In all such problems, however, the supreme test is that of actual trial, which develops, in spite of all the theories influencing the preliminary design, faults which can be remedied only by gradual elimination. It is from experience, and not in obedience to any theory, that we have learned to design magnets which are decidedly stubby ; that is, have very short magnetic circuits, short poles with not too great distances between them, and a maximum amount of current, which is obtained by winding with ribbons of copper instead of round wires, thereby increasing the amount of current and decreasing the voltage, and therefore the tendency to leak, short-circuit, or burn out.

The main commercial objects of magnetic separation are, first, the diminution of the amount of earthy gangue, with a consequent increase of the percentage of metallic iron in the product, and, second, the incidental elimination of phosphorus (usually present in apatite), and often of sulphur or titanium. A crude ore, carrying about 30 per cent, of iron, and reasonably coarse in structure, can be concentrated to 66 or 68 per cent, very readily. The loss of iron as magnetic oxide in the tails, in practical everyday running, will not exceed 3 to 4 per cent., while the total loss in the tails will depend upon the amount of iron present in the crude material in a non-magnetic state, such as the sesquioxide, silicates, and sulphides, though each of these may be at times somewhat magnetic, the sulphides especially, one variety of which, pyrrhotite, is notoriously so.

There is a general protest from all magnetic-separating experts against the usual method of judging results by percentages of metallic iron. Every one familiar with the subject through actual practice appreciates the misleading nature of this test in comparing results from different separators working on different ores. Especially is this true with regard to the loss in tails. Some rich ores leave, after separation, a very small amount of tails, so that a relatively minute quantity of iron lost may yet make a large percentage in the scanty tailings, while low-grade crude ore of the same mineralogical character and physical texture may, on account of the greater bulk of the tails, present, apparently, a much better showing in percentage of loss. The only proper way, in such comparisons, is to determine the percentage of magnetic oxide saved, and the percentage lost, out of the original amount in the crude ore. This gives a basis for comparison, as to the efficiency of the machinery and its adjustment, which is not misleading.

For instance: An ore carries 38 per cent, of metallic iron in the crude, of which 3 per cent, is in silicates (hornblende), the other 35 per cent, corresponding to 48.3 of magnetic oxide of iron. In examining the results of separation, we find that the heads compose one-half of the original material by weight, and carry 67 per cent, of iron, or 92.5 of magnetic oxide, equal to 46.3 out of the original 48.3 in the crude ore, while the tails contain the remainder, which is 2 per cent, of magnetic oxide out of the original 48.3 in the crude material; but this 2 per cent, is 4 per cent, of the weight of the tails themselves, which have only half the weight of the original material. In this case direct analyses of the tails would show 4 per cent, of magnetic oxide, equal to 2.896 of metallic iron, and also 6 per cent, of iron from the silicates, which, as the weight is only one-half, would be doubled in percentage, or a total of 8.896 per cent, in the tails. Yet there has been, in reality, only a loss of the original 3 per cent, of iron in the silicate and 1.448 of the original 35 of metallic iron, or 4.448 in both. This discrepancy between the apparent and the actual results is the greater, as the proportion by weight of the tails compared with the crude material is less.

After all is said, it still rests with the crushing and granulating part of the plant whether there be a financial success or failure. In nearly every case the crushing costs from four to five times as much as the magnetic separation, and requires, moreover, the greater part of the original cost of installation.. It is for this reason that we believe that a separator, which will relieve the crushing-plant of a considerable portion of its work,thus permitting the use of a smaller plant for a given aggregate product, and greatly lessening both the initial outlay and the cost of current repairs, and which accomplishes this result by its ability to divide the coarsely-crushed mass of crude material into various distinct grades, each of which may be specially treated afterwards, according to its needs,must be a factor of great importance in the problem of magnetic separation.

Another important point in favor of this machine is its adaptability to wet separation, by which I mean, to the treatment not of partially wet or damp material, but of material which is acted upon by the alternating-poles when wholly below the surface of water. The action in this case is the same as in air, with the additional advantages of the solving and washing effects of the water, as well as the diminution of gravity of the particles, which fall more slowly from the belt. For separating very dusty ores, the use of water is indeed essential, especially when the fine dust is, in considerable part, apatite, which is liable to cling to the magnetite and, in the dry process, to be carried into the heads in spite of strong air-blasts. Under water, there is no tendency on the part of any earthy minerals to cling to the magnetite; all the dust is washed off immediately, and the heads come out in a thoroughly cleansed condition, carrying 2 or 3 per cent, more iron, and considerably less phosphorus, than by the dry process.

The separator here described can be operated either wet or dry, without other change (for the latter purpose) than draining off the water from the tank and attaching an exhaust-fan. When specially constructed, however, for dry work, the frame and arrangements are somewhat modified.

As I remarked at the outset, the machine has grown up naturally and gradually out of a very careful study of the whole subject, and especially after examination, on the ground, of nearly all the notable separating-plants in this country, an investigation which convinced the writer that there was still abundant room at the top for a new and practical separator. Its success is largely due to the co-operation of Mr. Axel Sahlin, the engineer of the International Ore- Separating Company, to whose ability and experience the credit should be chiefly ascribed for the mechanical compactness and simplicity of the large machines.

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magnetite - an overview | sciencedirect topics

In the VNIR, magnetite and maghemite display low reflectance, around 2% for the former and 11% for the latter (Figure 6.6). In the 600014,000nm wavelength region, magnetite reflects poorly, but its reflectance baseline shows an increase toward longer wavelengths with such a low degree that magnetite can only be indirectly indicated by a significant vertical offset in the spectrum (Schodlok and Ramanaidou, 2011). Work on vibrational spectroscopy of magnetite has been carried out, for example, by numerous studies (e.g., Gasparov et al., 2000; Lane et al., 2002; Liese, 1967; Chamritski and Burns, 2005; Ebad-Allah et al., 2009).

Magnetite is simply iron corrosion products in the presence of a reducing environment [65]. Numerous researchers have been worked out to investigate the magnetite adsorption capability for the sorption of few radionuclides [66]. Magnetic iron oxides like magnetite (Fe3O4) and maghemite (Fe2O3) can be tailored to get improved magnetic properties, lower toxicity, and lower cost. Very less work was found in the synthesis of chitosan/magnetite composites for the elimination of heavy metals in contaminated water [67]. Tran et al. [67] observed that hydrogel (2-acrylamido-2-methyl-1-propanesulfonic acid) showed higher attraction for the elimination of impurities, while Yang and Chen [68] synthesized cross-linked chitosan-magnetite composites with the help of epichlorohydrin as the cross-linking agent. It was observed that alteration by cross-linking did not always decrease adsorption capacity.

Hematite and magnetite, the two predominant iron ores, require different processing routes. High-grade hematite direct shipping ores (DSOs) generally only require crushing and screening to meet the size requirements of lump (typically between 6 and 30mm) and fines (typically less than 6mm) products. Low-grade hematite ores require additional beneficiation to achieve the desired iron content, but the comminution of these ores still generally only involves crushing and screening, which is not particularly energy-intensive. Conversely, fine-grained magnetite ores require fine grinding, often to below 30m, to liberate the magnetite from the silica matrix, incurring greater costs and energy consumption. The comminution energy consumption could be over 30kWh/t, an order of magnitude higher than for hematite ores. However, with the depletion of high-grade deposits and strong demand for steel, a greater number of low-grade deposits are being developed.

To operate viably and sustainably, there is a need to reduce costs and energy consumption, particularly of the energy-intensive grinding required for low-grade magnetite deposits. This chapter reviews current iron ore comminution and classification technologies and presents some examples of flowsheets from existing operations. New trends and advances in comminution technologies are presented and discussed, particularly with regard to the impact on energy, operating, and capital costs.

Magnetite appears to be the main deposit on oil and gas production systems under high temperature conditions >150C (302F) and anoxic conditions, especially on carbon steels [31,32]. Even though various models have been developed to predict Fe3O4 solubility, predictions made from these models are only applicable below 100C (212F) at low pressure and in low TDS brine [33]. Limited research on the effect of high pressure and salinity on solubility of magnetite has been conducted.

Measuring the magnetite solubility has proven to be more difficult than that of other oxides, such as NiO, due to the reductive dissolution of magnetite from Fe(III) to Fe(II) [32]. Thus the reduction potential of the entire system plays an important role in magnetite solubility. In more complicated synthetic brines with high ionic strength, the reductionoxidation (redox) potential, which controls the dissolved iron concentration in the produced saltwater may cause large differences in the observed solubility.

Magnetite solubility experiments were conducted to determine the Ksp value at different temperatures and pressures. The results vary from the ones reported in the literature. For example, at room temperature and 345bar (5000psig) the total dissolved iron concentration is 0.068mg/L, which is about six times lower than the literature reported total Fe concentration (0.44mg/L). The effects of various reaction parameters on magnetite solubility were also studied and detailed results can be found in Yan etal. [34]. A change in pH or Eh has a much greater effect on magnetite solubility than pressure and temperature in this preliminary investigation.

Magnetite is often contaminated with titanium, forming minerals like ilmenite. The contaminated mineral shows an appreciable degree of magnetism. This property is made use of in the separation of ilmenite from other economical minerals such as rutile, monazite, zircon, leucoxene in Western Australia, Weipa in Queensland, Kerala in South India and other places where heavy minerals are present in beach sands.

The ionic model of magnetite is considered as Fe3+ [Fe3+ Fe2+] O42. The crystals are cubic with an inverse spinel structure. The cations [Fe3+, Fe2+] are in the octahedral sites. The Fe3+ is half in tetrahedral and half in the octahedral sites. The spontaneous magnetism exhibited by magnetite is therefore entirely due to Fe2+ per Fe3O4. The electronic configuration of Fe3+ is (3d)5 and that of Fe2+ is (3d)6. Quantum mechanics has helped establish discrete changes in magnetic moments that can occur. The orientations of magnetic moments in the crystals are either parallel or anti-parallel to the applied magnet field.

Magnetite is a ferromagnetic iron oxide of inverse spinel structure with the cubic packing of oxygen anions and iron cations located at tetrahedral and octahedral sites. In stoichiometric magnetite Fe2+ occupies half of the octahedral lattice sites because of the greater ferrous crystal field stabilization energy, while Fe3+ species occupy the other octahedral lattice sites and all tetrahedral sites (Cornell and Schwertmann, 1996). Electron transition between the Fe3+ and Fe2+ ions provides the half metallic properties of magnetite.

Figure 15.2 shows the representative X-ray diffraction diagram of Fe3O4 NPs. The peak intensity can give information about the proportion of iron oxide in a mixture by comparing it with the reference peak intensities. The line bordering parameter includes information about the crystal size that can be obtained using the Scherrer equation (Calvin et al., 2003). At the presented data (Figure 15.2) the patterns are close to those of maghemite -Fe2O3 and additional examination is needed to reveal the magnetite phase. Fourier transform infrared spectroscopy and Mssbauer spectroscopy can indicate the superstructure parameters of analyzed materials (Goti et al., 2009). As Fe2+ cations of magnetite are susceptible to oxidation the traces of impurities are always detected.

Without a special coating magnetite is susceptible to oxidation that deteriorates its magnetic properties. Oxidation and agglomeration of NPs can be considerably decreased by modification with different agents. Figure 15.3 shows the transmission electron microscopy (TEM) images obtained for 0.5% starch-stabilized magnetite NPs. The electronic diffraction pattern is inserted. Size, distribution, and shape of the particles can be analyzed. The average size of observed NPs is 105nm. For nonmodified control the tendency to form agglomerates is pronounced. The addition of starch as a stabilizer decreases the amount of agglomerated NPs (Soshnikova et al., 2013). However, the presented example is likely an exception model of massive agglomeration of nonmodified particles because TEM analysis usually does not reflect the real agglomeration tendency of the material for the specificity of sample preparation and additional examination by means of other methods is needed. Sometimes TEM may help to distinguish the crystalline part of the particles from the amorphous core. The atomic level of the NPs (lattice defects, vacancies, surface arrangement, self-assemblies, etc.) may be analyzed by means of high-resolution transmission electron microscopy (Wang, 2000).

Time-dependent changes in the dispersed material can be studied by scanning microscopic observations. Atomic force microscopy (AFM) allows to obtain the height profiles and estimate the lateral sizes of micro- and nanoobjects. In comparison to TEM the sample preparation is simplified and it is possible to study the nonconductive materials that can help to analyze the real sizes of organic modified NPs. The glycerin-coated NPs obtained 24 and 75h after the synthesis from AFM are presented in Figure 15.4. One can see that the highly dispersed NPs of 1012nm in size for approximately 50h storage in water at room temperature form agglomerates with the size up to 200nm.

The properties of dispersed NPs can appreciably differ from those obtained after drying and preparing the microscopic samples. That is why the liquids containing NPs for use in biomedical testing should be analyzed excluding the stage of particle extraction. Dynamic light scattering (DLS), also known as proton correlation spectroscopy, is a powerful method to determine the size distribution of dispersed material in a broad range of concentrations. It is based on the correlation between the size of the particle and its Brownian motion. Particles in aqueous medium are illuminated by laser and the intensity fluctuations of scattered light are analyzed. DLS provides the size evaluation of dispersed magnetite NPs by measuring the translational diffusion coefficient (D) distribution. The hydrodynamic radii Rh of spherically shaped particles can be calculated from the diffusion coefficients by the StokesEinstein equation: D=kBT/6gRh, where kB is the Boltzmann constant, T is the absolute temperature, and g is the viscosity of the analyzed medium. The calculation is correct for spherical and homogeneous particles and gives only an estimate of hydrodynamic radii in other cases.

Figure 15.5 presents the DLS data for starch-modified magnetite NPs for three different concentrations of starch. The optimum starch concentration was determined according to the investigation (Soshnikova et al., 2013). From the data it can be seen that there is a concentration value of 0.5% (mass) that allows to obtain a stable dispersion of NPs with an average hydrodynamic radius of 45nm. A 0.1% concentration is not so effective and led to an increase in the average radius value up to 100nm, while the use of 1% starch concentration caused the growth of the system viscosity and appearance of concentration effects.

Time- and temperature-dependent changes can be revealed by DLS. Figure 15.6 presents the distribution of 0.5% starch-stabilized magnetite NP dispersion as the temperature increases up to 70C. According to the data the dispersions demonstrate chemical stability within the studied temperature range.

DLS is more sensitive for larger particles (10nm), whereas the analytical ultracentrifuge (AUC) provides a more sensitive probe for smaller particles (Brown and Schuck, 2006). The method is based on measuring light absorption or interference optical refractive index of the analyzed material with the applied centrifugal field. Sedimentation velocity experiments monitor the entire time-course sedimentation and provide the sedimentation coefficient distribution c(s) of Lamm equation solutions:

where C is particle concentration, r is length that the particle passes under the centrifugal force in radial direction at the centrifuge cell, t is experimental time, w is angular velocity of the rotor, D is diffusion coefficient, and s is sedimentation coefficient. Based on the known c(s) distribution, the average Stokes radii of analyzed particles can be determined. The method is widely used in research of protein macromolecules, while its applications for dissimilar systems, such as crystalline NPs and organic stabilizers, are limited. However, some efforts were made to analyze the very small fractions of stabilized magnetite NPs where the small particles (<10nm) were preliminarily separated from agglomerates. Figure 15.7 shows the c(s) distribution for the 0.5% starch-modified magnetite NPs (Soshnikova et al., 2013). The corresponding average Stokes radius value is 4.8nm.

Magnetic properties of magnetite strongly depend on such factors as the NP size, shape, and chemical phase. Bulk magnetite can be described as ferrimagnetic as a result of the parallel alignment of magnetic moments of the tetrahedral site and antiparallel alignment of the Fe2+ and Fe3+ spins of octahedral sites. However, when the particle size is decreasing the tendency to spontaneous magnetization becomes weaker and magnetite NPs tend to demonstrate paramagnetic or superparamagnetic properties. To study magnetic characteristics several techniques were developed. Magnetic particles can be characterized by measuring their magnetic transition temperature, saturation magnetization, or magnetic susceptibility. Magnetic transition temperature (Curie temperature) corresponds to a point where the intrinsic magnetic moment changes its direction and the temperature values can be obtained by means of differential thermal analysis (Thapa et al., 2004). Saturation magnetization reflects the value of magnetization when an increase in the applied external magnetic field cannot further increase the magnetization of the material. It can be measured using a magnetometer. For the particles <100nm, the size effects are observed. Thapa et al. presented the decrease in magnetic transition temperature and saturation magnetization as the size of NPs decreases from 90 to 6nm (Thapa et al., 2004). The oxygen content in small NPs is reduced, which leads to the lowering of the cation valance and increase of Fe2+ species content that possesses a higher ionic radius than Fe3+. It consequently results in an increase in the unit cell volume of small NPs (Thapa et al., 2004). The authors also observed a drop in magnetization for the NPs <10nm, which can be explained by the pronounced surface effect. Magnetization of the core atoms is higher than that of the surface ones and as the size decreases the surface contribution becomes prominent. Small monodomain magnetite NPs demonstrate superparamagnetic behavior (SPIONs) and exhibit magnetization only in the presence of an external magnetic field that attracts a great deal of interest in their potential applications in biomedicine (Lin et al., 2009). Sometimes, to characterize magnetic materials, it is enough to measure their magnetic susceptibility. This indicates the dimensionless proportionality constant of the material magnetization degree in response to an applied magnetic field. It was already mentioned that NPs magnetic properties can be significantly different from those of the bulk material. The principal mechanism of the magnetic susceptibility dependence on the particle size is the transition from multidomain to monodomain particles. Magnetic susceptibilities of magnetite NPs obtained by laser ablation and chemical synthesis are presented in Table 15.1.

The samples were obtained by drying the dispersion droplets at the coverslips. For the specified cylindrical volume, the NPs, mass and density were determined accurately (within 1mg). Magnetic susceptibility was measured by gravimetric analysis similar to the Faraday method. The conventionally used enormous solenoid was replaced by a cylindrical permanent magnet that maintained the constant gradient of magnetic induction at the sample placement. Magnetic induction distribution measurement along the magnet axis was carried out by the micrometrical sensor and inductometer with an accuracy of 5mT. From the presented data it can be seen that the magnetization of the NPs derived from laser ablation is more pronounced than that for the chemically synthesized.

Magnetite possesses an inverse spinel structure AB2O4 (space group Fd3m; a=8.39) (Fig.5.1A), wherein oxygen anions form a cubic face-centered (fcc) lattice and large interstices between O2 are partially occupied by iron cations. Tetrahedral A positions are occupied by Fe3+ cations, while octahedral B positions are equally occupied by Fe3+ and Fe2+ cations (FeA3+[Fe2+Fe3+]BO4). Fig.5.1B shows magnetite electronic structure [2,3]. The density of states (DOS) occupied by the electrons of the octahedral B sites can be thought of in terms of a spin-up () band and a spin-down () band which are split by an exchange energy. The five degenerate d-electron levels of Fe ions are further split by the crystal field, into three degenerate t2g and two degenerate eg levels. For both Fe2+ and Fe3+ ions, five electrons occupy the majority t2g and eg levels. The extra electron of the Fe2+ ion occupies the minority t2g band, which is the only band located at Fermi level EF, giving rise to half-metallicity (100% spin polarization). The high room temperature conductivity (1041051m1; which is 0.1% of Cu metal at 300K) of magnetite is attributed to the hopping of this electron between octahedral (Fe2+Fe3++e) B sites which dominate the DOS around Ef.

Figure5.1. Illustration of tetrahedral and octahedral sites in inverse spinel structure of Fe3O4 (A).Density of states occupied by electrons of the ions at the two sites (B). Essential spin conservation and ferromagnetic ordering in Zener double exchange mechanism (C).

Zener double exchange best explains this hopping mechanism (Fig.5.1C) [4]. The term double indicates here that an extra electron of Fe2+ ions is transferred to the empty orbitals of Fe3+ by displacing electrons from the intervening O2 ions in a double-exchange process: Fe2+ to O2 and O2 to Fe3+. An antiparallel coupling is present between the spin-down () electron coming to Fe3+ from neighboring 2p O2 orbital, at the same time the empty 2p O2 orbital accepts the extra hopping electron from Fe2+ creating a parallel coupling. This overall energy saving mechanism leads to a FM ordering with conservation of spin. The probability for exchange is a sensitive function of both the metaloxygen distance and of the Fe3+O2Fe2+ angle, being greatest when theangle is 180 and smallest when it is 90. The Fe3+O2Fe2+ bond angle for the ions is 90 for BOB sites, the AOA site's angle is 80, and the AOB site's angle is 125. Therefore, AB interaction is the strongest and favors antiparallel alignment to save energy. Thereby, all the A spins align parallel to each other and the B spins do the same (Fig.5.1A). At B sites, double exchange creates FM alignment in BOB, resulting in a magnetic moment of (5+4) B. To decrease the energy the five unpaired electrons of the A site align antiferromagnetically with the nine parallel on B site, lowering the magnetic moment to (95=4)B. An additional unquenched angular moment (L)of Fe2+ ions gives total moment J=L(0.2)+S (4)=4.2B.

Upon cooling of magnetite below 120K, the electron hopping between Fe2+ and Fe3+ ions freezes and a combination of 2+and 3+species then arrange themselves in a regular pattern without moving (charge ordering). In this nonconducting state the stagnant Fe2+ ions are JahnTeller (J-T) active [2], this means, the extra electron in Fe2+ has a choice between occupying anyone of the three available half-filled orbitalsdxy or the two dxz/yz, as they all have the same energy (depicted by arrows in Fig.5.2A). Electrons prefer to occupy the orbit with the least energy. Therefore, to break this choice, an effective energy separation between dxy and dyz/dzx is created if the four FeO bonds (depicted by arrows in Fig.5.2A) in the xy plane are elongated or contracted. The negative value of t2g signifies that the energy of dxy is lower than that of dyz/dzx, that is, tetragonal distorted Fe2+O6 octahedra with elongated FeO bonds in the xy plane. On top of this, an additional structural distortion in which B site FeFe distances within linear Fe3+Fe2+Fe3+ units (depicted by the green ellipsoid) are anomalously shortened showing that electrons are not fully localized as Fe2+ states but are instead spread over the three sites resulting in highly structured three-site polarons defined as a single trimeron [2]. The JT distortion in Fe2+O6 octahedra mentioned earlier directly couples to the neighboring Fe3+O6 octahedra constituting the trimerons, although they are JT inactive in the first approximation. Due to trimeron formation, distances from Fe2+ states to their two B site neighbors in the local orbital ordering plane are anomalously shortened (Fig.5.2A). The cumulative effect of this trimeron shortening penetrates throughout the crystal in the various trimeron locations to significantly perturb the cubic magnetite structure to the complex overall distortion (Fig.5.2B). The cubic spinel [a=b=c] type structure of magnetite distorts to a monoclinic superstructure with Cc space group symmetry [a=b c] [2,2,2]. This structural transformation was first found by Verwey in 1939 and was named after him. The charge, orbital, and trimeron orders of magnetite stand out as perhaps the most complex electron ordered ground state known.

Figure5.2. Energy separation due to JahnTeller distortion (down), depiction of trimeron concept in single (top) Fe+2O6 octahedra (A) [2]. Trimerons distributed over the lattice points [2] (B). Changes in magnetization, resistivity, and specific heat at Verwey temperature, Tv (C) [5].

Because of this structural transformation in Fe3O4, many physical properties (specific heat, magnetization, and resistivity) show abrupt change around VT [5] (Fig.5.2C). Even after intense research there still exist two major schools of interpretation: the first one interprets the Verwey transition as a transition driven by charge/orbital ordering and the second one exploits the mechanism of a lattice distortion-driven charge-ordering leading to a metal-insulator behavior.

Magnetite NPs are commonly used as T2 contrast agents because they accelerate spin-spin relaxation. Superparamagnetic iron oxide particles form strong local magnetic field gradients that affect the protons surrounding these particles. This interaction depends on the distance between superparamagnetic particles and protons. First of all, two physico-chemical characteristics of the contrast agentthe mobility of the NPs and their magnetizationhave an effect on the time of transverse relaxation. Thus, the size, degree of aggregation, and magnetization, as well as the state of NPs due to phase transitions, influence the contrasting properties of superparamagnetic particles (Hingorani et al., 2015).

The presence of contrast agents changing the longitudinal relaxation in the object of research causes an increase of the Mr signal intensity. Such substances are often called positive contrast agents. On the contrary, the substances that predominantly modify transverse relaxation are called negative contrast agents, since they cause the appearance of regions with a low signal intensity in Mr images.

Currently, a number of preparations containing superparamagnetic particles based on iron oxideSinerem, Resovist, Feridex, Ferumoxtranare produced. Usually in a clinical MRI, superparamagnetic iron oxide NPs are used to determine liver diseases because they are selectively absorbed by Kupffer cells in the liver, spleen, and bone marrow (Na et al., 2009). As a result of the disease normal structure of liver tissue is broken, then this area will have a deficiency of Kupffer cells. Because of the small absorption of NPs by atypical liver tissue, the Mr tomograms show a strong contrast between normal and atypical tissue.

Nevertheless, high absorption of NPs in the liver leads to their rapid excretion from the blood plasma, which greatly reduces the time of their circulation in the bloodstream. It is important to note that the circulation time of NPs in the blood strongly depends on their size. In clinical MRI, iron oxide NPs having the size <50nm are also used to visualize lymph nodes (Harisinghani et al., 2003). Since the NPs are very small, their extravasation from the blood vessels to the interstitial space can occur. Thus, the NPs can be transported to the lymph nodes through the lymphatic vessels. Also, the stem and immune cells are preloaded with superparamagnetic iron oxide particles coated with carbon and dextran as a T2-contrasting agent and then transplanted into the body, which allows one to monitor them in vivo (Lepore et al., 2006; Qiu et al., 2007).

Superparamagnetic iron oxide NPs coated with ascorbic acid can be considered as a potential Mr contrast agent, which simultaneously possesses antioxidant and therapeutic properties (Sreeja et al., 2015). It is shown that antioxidant properties of ascorbic acid persist after its adsorption on the surface of iron oxide NPs. The values of relaxation time of such particles are comparable with the values of relaxation time of the currently used clinical preparations, for example, ferumoxtran.

To obtain NPs suitable for use as an MP contrast agent, block copolymers are used during the synthesis of NPs by the co-precipitation of iron salts in the presence of a base (Basuki et al., 2014). The properties of NPs, including colloidal stability and relaxation, can be varied by changing the concentration of the copolymer and carefully selecting the anchor groups. The value of r2 for a colloid of such NPs is 370mM1s1, which is similar to the characteristics of the commercial drug Resovist.

It is shown that the contrast enhancement in T2 depends mainly on the degree of aggregation of NPs having a polymer coating using NPs, while the effect of the polymer itself on the Mr signal is relatively small (Carroll et al., 2011). The authors (Carroll et al., 2011) suggest the hypothesis that the control for the aggregate formation can serve as a means for achieving high contrast while maintaining colloidal stability. However, it should be noted that strong aggregation of magnetite NPs leads to artifact arising on Mr tomograms because the magnetic moment of the aggregates becomes very large. This is due to the fact that the magnetic field gradients are used in MRI for spatial encoding of information, and their strong local heterogeneity, as well as an increase in the magnetic permeability of the region of interest, breaks this process, resulting in the formation of spatial distortions on the tomograms. The proton relaxation rate also strongly depends on the particle size of iron oxides, in a less degreeon the composition of their coatings and the hydrophilicity of their surface (Duan et al., 2008).

The authors of this research (Zhao et al., 2013) describe the synthesis of iron oxide NPs in the form of an octapod and show the possibility of their application as a T2 contrast agent for MRI. It is shown that such particles more efficiently accelerate spin-spin relaxation in comparison with spherical particles. This fact solves the problem of achieving the necessary contrast at a relatively low concentration of NPs. For example, sufficient MRI contrast in vitro is obtained by the authors at the concentration of 0.2mM of these NPs, which is better in comparison with the spherical iron oxide particles described in the same work (> 0.4mM).

However, it should be noted that the synthesis of such particles by the method of thermal decomposition is quite complex and the problem of its adaptation for mass production remains actual. In addition, it is difficult to predict colloidal and chemical composition stability of the NPs with a similar surface to volume ratio.

To increase the accuracy of diagnosis with MRI, contrast agents changing both longitudinal proton relaxation and transverse relaxation are developed. For example, a core-shell structure is proposed for changing T1 and T2 relaxation (Shin et al., 2014) where superparamagnetic NPs of iron oxide are used as a core. The NPs are coated with silicone dioxide shell and then a layer of a paramagnetic compound that alters predominantly longitudinal relaxation is adsorbed onto the silicon dioxide.

There is a problem to differ the effect of contrast agents and artifacts on Mr images. MRI artifacts are caused by certain endogenous conditions, such as calcification, the presence of fat, hemorrhage, blood clots, or air bubbles. Obviously, these artifacts are problematic because they mimic signals coming from the Mr contrast agents. Thanks to the use of the contrast agents changing T1 and T2 relaxation the possibility of false diagnosis due to the influence of such artifacts is eliminated.

A number of works describe the concept of multifunctional nanoobjects, which can be visualized by various methods. It demonstrates the possibility of obtaining contrast agents based on superparamagnetic NPs accelerating transverse relaxation (T2) in MRI and having luminescence (Lee et al., 2006). The concept of multifunctional hybrid NPs can serve as a technological platform for a new generation of biological sensors.

The commercial particles coated with dextran of bacterial origin have a number of drawbacks, such as increased allergenicity (Mornet et al., 2005), low penetration efficiency in the cell by endocytosis of the liquid phase (Wilhelm and Gazeau, 2008). Dextran is also inconvenient to attach additional functional groups that could improve the internalization of particles into cells. In addition, a dextran shell is rapidly destroyed by lysosomes, resulting in the unwanted release of iron oxide into the cytoplasm (Arbab et al., 2003). Due to high biocompatibility of phospholipids, the phospholipid bilayer shell has a number of significant advantages in comparison with polymer NP stabilizers (Lacava et al., 2004). In addition, the phospholipids adhere to the surface of the particles well (De Cuyper and Joniau, 1988) and degrade in the cytoplasm much slower (Al-Jamal and Kostarelos, 2007), which allows one to reach large particle concentrations in the cells that require for NMR imaging. It is noted that the application of large monolamellar magnetoliposomes makes it possible to obtain a very good contrast in angiographic studies on animals (Martina et al., 2005).

At present, a lot of works are devoted to obtaining and studying magnetoliposomes containing MNPs both in the internal volume and inside the lipid bilayer. For example, the magnetoliposomes are produced by enclosing maghemite NPs in the internal volume of the vesicles (Martina et al., 2005). The resulting magnetoliposomes were used to increase the contrast in magnetic resonance angiography. In the study (Chen et al., 2014), the authors subsequently incorporate hydrophobic maghemite NPs in a lipid bilayer. The presence of maghemite NPs in the liposome envelope makes it possible to provide the remote release of encapsulated cytostatic (doxorubicin) by an alternating magnetic field (Chen et al., 2014).

The delivery and in vivo monitoring by MRI of polyelectrolyte microcapsules containing superparamagnetic NPs are shown in (Yi et al., 2014). The authors present that magnetic microcapsules do not exhibit obvious acute toxicity after the injection in the tail vein. Magnetic microcapsules enhance T2 Mr contrast in liver over 6h after administration. This study shows relatively faster clearance of Parg/DS magnetic capsules than the PAH/PSS ones in liver.

Superparamagnetic iron oxide NPs incorporated into the shells of polyelectrolyte multilayer capsules have different magnetic and NMR relaxivity properties than NPs freely dispersed in a sodium borate buffer solution (Abbasi et al., 2011). As shown superparamagnetic NPs in the polyelectrolyte shell have a smaller r2 relaxivity value compared with an uniformly distributed ensemble of NPs. In addition, the blocking temperature TB for the ensemble of MNPs decreases as a function of packing fraction.

Composite microcapsules are able to change the MRI contrast in T1 and T2 regime by varying the concentration of magnetite NPs and due to enzymatic degradation of the capsule shell in vitro and in vivo (German et al., 2016). Both relaxivity values depend on the average distance between the NPs in the microcapsule shell that can be easily varied for LbL approach by the changing magnetite NP layers, magnetite NP concentration in the colloid that are used for layer deposition (Fig. 6.3). The microcapsules with an average distance between the magnetite NPs equal to 54nm exhibit the maximum of Mr signal intensity change for the T1- and T2-weighted images. It is also shown that enzymatically destruction of microcapsules with high concentration of magnetite NPs in the shell leads to significantly increasing of Mr contrast. This effect can be used for the evaluation of degradation time of microcapsules in vivo.

This section describes the composition of the EPRI/SGOG magnetite solvent, the crevice solvent, the copper solvent, and the passivation solvent. The magnetite solvent is for the dissolution of the bulk deposit. The crevice solution attacks the deposit that is located in the crevice between the tube and the tube support plate. The crevice solution needs some mechanical help in order to replenish the solvent in the crevice area. The copper step dissolves and removes the copper deposits while the passivation step, which is applied after the copper step, puts a small oxide coating on all of the bare carbon steel surfaces in order to reduce the corrosion of the carbon steel during the following startup and operation.

These parameters were only finalized after many beaker tests followed by potboiler tests. The pH was selected after the testing of several more acidic solutions. The resultant pH was a compromise of dissolution rate vs the carbon steel corrosion in the SG. Most processes that employ chelates (EDTA) typically require temperatures approaching boiling in order to achieve an acceptable rate of dissolution. How the temperature is achieved will be discussed in a later section.

High temperature is required to allow venting of the SG through the SG pressure relief valve. The boiling results in the expulsion of the depleted solvent in the crevice so that the crevice can be replenished with fresh crevice solvent that has dissolution capability remaining. The venting process will be discussed later on a section on heating and venting SGs.

As stated earlier the passivation step is utilized to leave the exposed carbon steel in the SG with a protective coating on the surface to reduce the corrosion of the carbon steel during startup and initial operation prior to the buildup of the normal operational corrosion film layer. The passivation step is composed of the following:

The generic EPRI/SGOG process was developed and qualified for a well-defined range of application conditions. Any major deviation from these conditions should be specifically qualified in a major test vehicle similar to those used in this qualification program. Plant-specific testing should be done before cleaning to verify process effectiveness and to confirm acceptable corrosion with plant materials of construction. It is recommended that actual plant sludges be used for this testing whenever possible.

3-Aminopropyltriethoxysilane coupling agent has been used to increase higher saturation magnetization, storage modulus, and glass transition temperature of epoxy composite.3 Figure 2.73 shows results of modification of magnetite by silane.3 Thickness of silane coating clearly depends on silane concentration.3 Too thick coating reduces magnetic properties of composite.3

cable scrap processing

Today, copper ores mostly contain a copper content of 0.6 - 1 %, i.e. 100 tons of rock have to be melted for one ton of pure copper. It is therefore only natural that the CO2 footprint and the energy balance of copper can be massively improved with the reuse of recycled copper. Due to the enormous amounts of copper that are bound in cables, cable scrap is an essential raw material.

Convince yourself of the greater added value for your cable scrap processing by using IFE solutions - from the control screening to the final removal of magnetizable material from the non-ferrous concentrate!

IFE Aufbereitungstechnik GmbH recommends a control screening as this breaks up the lumps, separates clumps of plastic prior to further processing and ensures that there is no negative impact on the purity of the non-ferrous fraction in the subsequent eddy current separation process.

The feed material is separated by means of an IFE permanent magnet drum with alternating polarity around the perimeter in order to separate the ferro-magnetic particles and to protect downstream units.

The cable scrap is processed with IFE's eddy current separator INP ENOS with a special eddy current bar. The manually adjustable "three product splitter system" produces a weakly magnetizable fraction (stainless steel separation), a residual fraction (plastics), and a non-ferrous fraction.

The residual fraction from the eddy current separator is also further processed with the IFE-SORT fine sorting system. The special perforated deck installed in the system produces three fractions which enables the remaining non-ferrous metals to be recovered: Heavy material (bulk weight approx. 3,0 t/m), undersized particles from the perforated deck (primarily copper strands, Cu content 98 %) and light material (plastics).

The IFE high-intensity roll separator is used for the final fine separation of particles with weakly magnetic properties. This strong-field magnetic separation removes the remaining magnetizable material (brass) from the non-ferrous concentrate (approx. 95 % Cu content).

All kinds of copper waste (from dust to granules) can be reused in the smelter. Any impurities (e.g. tinned strands, brass or lead) are given off into the slag or dust in the melting furnace. Particularly pure copper granules (min. 1 mm thick) are sold as Milberry (amer. ISRI) or Kabul (ger. VDM) directly to copper foundries and therefore do not require a smelting plant as an intermediate step.

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developments in the physical separation of iron ore: magnetic separation - sciencedirect

This chapter introduces the principle of how low-grade iron ores are upgraded to high-quality iron ore concentrates by magnetic separation. Magnetite is the most magnetic of all the naturally occurring minerals on earth, so low-intensity magnetic separators are used to upgrade magnetite ores. On the other hand, because oxidized iron ores like martite, hematite, specularite, limonite, and siderite are weakly magnetic, high-intensity magnetic separators and high-gradient magnetic separators are required to upgrade oxidized iron ores. Therefore, it is important to develop and optimize processing flow sheets according to the nature of iron ore to achieve both high recovery and high grade at a low cost. Three flow sheets for magnetite ores and seven flow sheets for oxidized iron ores separation are discussed.

ife newscorner - updates on ife

With our newscorner, we wish both to inform you and to keep you up to date on the latest happenings at IFE, interesting projects and trade fairs as well as many other highlights of the year!Sign up for our newsletter thus we can keep you up to date. Or follow us on Facebook, Youtube, Xing or LinkedIn!

The metal recycling facilities of Clayton County Recycling (CCR) Inc. are located in the Middle West of the USA. They collect, process, recycle and trade both ferrous and nonferrous metals. A wide range of IFE machines is operating there, reliably fulfilling several screening and separating tasks...

For more than seventy years, IFE Aufbereitungstechnik GmbH has been manufacturing machines for processing bulk materials. By relying on this wealth of experience gathered over decades and pairing it with continuing innovation, we find new approaches for making tried-and-tested machinery solutions available to other industries as well and putting them to use successfully...

Countless products are made out of plastic, paper and cardboard. With a material test IFE Material Handling was able to improve the efficiency of the recycling process of such a product and at the same time increase the degree of purity of the resulting plastic fraction...

On the one hand, IFE equipment is used to separate metallic components in order to market them as ferromagnetic fractions and as non-ferrous mix. On the other hand, IFE machines are used to increase the quality of the glass fraction before it is handed over to optical sorting equipment...

Moving to the 700 m building does not only bring more space and more efficient processes. The flexible equipment pool enables the IFE team to respond optimally to a wide range of applications, customer requirements and numerous new material compositions...

The high-tech mining company LKAB is one of Sweden's oldest industrial companies and in its ore facilities many heavy duty vibrating feeders and screening machines from IFE Aufbereitungstechnik GmbH are used...

LKAB, one of the largest iron ore mining companies in the world, and IFE, as a specialist for vibrating machines and magnetic separators, have been in a particularly intensive relationship for decades....

Today, copper ores mostly contain a copper content of 0.6 - 1 %, ie. 100 tons of rock have to be melted for one ton of pure copper. It is therefore only natural that the CO2 footprint and energy balance...

Due to the low number of active COVID-19 cases, rules were further loosened by the Austrian government by June 15, 2020. In compliance with the generally applicable hygiene regulations, the following changes have also been made at IFE...

The average lifetime of an artificial turf system is approximately 12 to 15 years. After that, it can be removed, and the recyclables it contains (rubber, sand, plastic) can be recovered. A particular challenge in the treatment of old turf waste lies in the separation process....

IFE Aufbereitungstechnik GmbH is continuing to expand its presence in Germany and founded a subsidiary company based in Essen on March 27, 2019 for this purpose. The management of the still young "IFE Aufbereitungstechnik GmbH Deutschland" in an interview about the reasons for this strategic step

IFE would like to thank its customers for their loyalty and trust during the years, but above all, its employees for their service and tireless commitment! Special recognition is given to the employee jubilees!

The company Schaufler Metals (Ybbs/Donau) in cooperation with the Montanuniversitt Leoben and IFE Aufbereitungstechnik GmbH as well as other partners conducted a perennial study of the development of innovative, dry processing methods for metallic composites.

According to the article Good as new in the may issue of the trade journal "The Construction Index Magazine", contractors operating in the south-west of England have no exuse to send waste from their sites to landfill anymore now that a 4m recycling plant has opened on the outskirts of Bristol. The plant was built by IFEs long standing partner TURMEC.

A bunker discharge unit for up to 2,000 t of copper ore per hour should be supplied to a Swedish mine. The dosing feeder must withstand the immense impact forces of the ore whenever the bunker is refilled.

In the mining industry, electromagnetic drive units are commonly used for vibrating feeders. Nevertheless, there are special situations in which drives reach their limits due to e.g. structural limitations or customer requirements. Read more about a specific use case in the sector of coke production!

In order to ensure that waste wood is allocated to the right usage cycle, proper processing is essential. In the article "Efficient Machine Solutions for Processing Waste Wood", you will learn more about the classification of waste wood by means of screening and sorting as well as the metal contaminants separation from used wood. Numerous application examples included!!

The preparations for the IFE Global Sales Meeting 2019 are in full swing! The entire IFE sales team and trading partners from 23 different nations will meet in Waidhofen/Ybbs from May 21st to 23rd for an international exchange. The GSM provides the perfect opportunity to share common goals and challenges, but also offers many possibilities for deepening knowledge of product innovations and exciting applications...

We are pleased to introduce a new face in the sales and project management team of IFE Aufbereitungstechnik GmbH: Daniel Schauppenlehner! In future, Daniel will be fully committed to IFE's international sales and will take care of our clientele in the French sales area. Due to his many years of experience in plant and mechanical engineering development and his current part-time study program for the Bachelor of Science, he brings in-depth knowledge...

For more than 70 years, we, IFE Material Handling, concern ourselves with the design and manufacturing of machines for bulk material handling. Since then, our name has been synonymous with quality, longevity and robustness.

A press release published by Eurostat on 04.03.19 shows that recycling rates and the use of recycled materials in the EU have reached record levels. The recycling rate of plastic packaging has almost doubled since 2005. Overall, the EU recycled in 2016 around 55 % of all waste excluding major mineral waste (compared with 53 % in 2010).

Where conventional screening machines become blocked or stuck, special screening machines for very demanding tasks are required. This is where the flip-flop screen TRISOMAT from IFE comes into use.In a Czech coal processing plant with a connected power plant, eight IFE flip-flop screens for the screening of fraction "nut 2" as well as coarse dust from lignite went into operation.

Two-thirds of the total quantity of raw iron required for steel production at the location in Linz, Austria is produced in blast furnace A. The renovation of the unit was scheduled for 2018 and successfully completed at the end of September. This meant that 39 feeders for blast furnace burdening delivered by IFE to voestalpine were checked. Some of the feeders have been in use since the 1970s and are at around 250,000 operating hours.

The IFE VIOS utilizes an absolutely new geometry of the magnetic system which causes a previously unprecedented repulsive force in the non-ferrous parts to be separated. This technology exceeds the sorting result of conventional eddy current separators. Targeted parameterization allows this rotor to concentrate different non-ferrous metals from each other or even PCBs from non-ferrous metals. Read more ...

The proven design of the IFE waste screen upper deck combined with the new resonance system VARIOMAT of the lower deck provide for an extraordinary double deck screen. In the context of a cooperation between IFE and HTL Waidhofen (school for higher technical education), a sensor prototype for early detection of worn screen panels was constructed for this type of screen. Read more...

IFE received an order to supply the largest sinter screens in the company's history to the Far East. The total of six linear vibrating screens are used to classify crushed cold sinter (< +100 C, total input: 955 t/h). Read more ...

For more than 70 years, the passion of IFE Aufbereitungstechnik GmbH has been in the construction of machines for bulk material handling. That, in turn, requires motivated and dedicated employees, accompanied by a constant growth of our team. Therefore we are pleased to introduce eight new staff members! Read more ...

The Industrial Emissions Directive of the European Union includes the stipulation that operating facilities (including waste treatment plants) are only approved if there is no hazard to the Environment. Read more ...

The project consortium Plastic Reborn, consisting of different chairs of the Montanuniversitt Leoben as well as the industrial partners OMV Refining and Marketing GmbH (OMV) and IFE Aufbereitungstechnik GmbH, received the special award Think the future young ideas for waste management 2018. Read more ...

The dominant opinion prevailing in the eddy current separator industry, namely that a higher poling frequency equates to a higher sorting quality, is causing some to look at the developments of the products available on the market with skepticism. More and more, the manufacturers of eddy current separators are steadily increasing the number of poles of their rotors and also their operating speed, presumably in order to serve the need for sortability of grain sizes smaller than 1 mm. Read more ...

In the current application, a heavy-duty linear vibrating screen was delivered to a Dutch steelworks to screen coke. The robust screen frame of the IFE screening machine type US 2150x9000 FSV - 2 UG60 (grain size 0-80 mm, feed capacity 250 t/h) consists of extremely durable rubber lined side walls, side fixing bars with molded ceramic and screwed and glued cross beams. Read more...

Experience from more than twenty years in the processing of wastes has shown us that with this type of heterogeneous mixture, which often contains fibrous or sticky material, it is essential to select a suitable screen for the classification. Read more ...

New and rapidly changing material compositions as well as shrinking product sizes, combined with higher collection costs, present the recycling industry with major challenges. In addition, the increased use of plastics in all substance groups is to be expected in the future, and thus the metallic materials will be further displaced. Read more ...

As the only manufacturer that offers package solutions in the product fields Conveyor, Screening and Magnetic Technology, IFE supplies tailor-made solutions for the processing of recyclables. At IFAT 2018 ...

At the end of April, Kttner Schwingtechnik presented itself as a joint venture of the companies IFE Aufbereitungstechnik GmbH and Kttner GmbH at the 61st Austrian Foundry Congress in Gurten (Austria) ...

Plastic waste is first checked for contaminants when it arrives at the recycling facility. This process removes impurities or foreign matter that could interfere with the recycling process. In the above case, the aim is to separate aluminum foil and a variety of aluminum parts from the plastic portion. The IFE Eddy Current Separator is ideally suited for this type of application...

The highest mechanical requirements are a prerequisite for efficient scatter.Steady flow through the spreader, large scatter range, good cross distribution and reliable results under all conditions the spreader performance depends on the density and size of the grit, which has to be monitored closely by fertilizer manufacturers...

In striving to secure our economic success in the future, we the IFE Aufbereitungstechnik always try hard to further develop our machines and technologies and bring them to the next level.In future, the development of mobile and semi-mobile machines will be an interesting topic at IFE...

For the first time, the IFE Aufbereitungstechnik was represented at the IFAT Eurasia in Istanbul. Eurasias Leading Trade Fair for Environmental Technologies took place from February 16th to 18th and was ameeting point for more than 11.300 representatives of the environmental sector from more than 70 countries. Around 230 exhibitors from all over the world showcased the latest solutions and products for the environmental sector on an exhibition space of 17.000 m. Together with our Turkish sales partner Enver Kse, the IFE Aufbereitungstechnik, represented by Christian Haas, presented itself at the Austrian group stand of...

The IFE employees proved their sporting talents at this year's 45th Lower Austrian Ski Championships on the Forsteralm. The organizers - the Landesskiverband N and the N Betriebssportverband - offered the participants a professional giant slalom run and an excellent slope preparation. In an ideal winter weather, Stefan Haselsteiner, Franz Fuchsluger...

In order to better position itself in the foundry machine market, IFE Aufbereitungstechnik GmbH has set up a joint venture together with the plant manufacturer Kttner. The existing market potential underlines the decision to merge the two companies.The subsidiary operates under the name...

Another successful year is coming to an end! Twelve eventful months passed by and now we look forward to the upcoming Christmas season.The IFE Aufbereitungstechnik takes a little breather.Therefore we closeour doors from 12/24/2016 to 1/8/2017. The last day for delivering goods is 12/23/2016, the first day of delivery in the new year is 1/9/2017. We would like to thank you for...

Recently, the IFE Aufbereitungstechnik supplied two linear vibrating screens of the type US 2400x8000 FSV-2UG80 for a copper ore mine in Mongolia.IFE has already equipped this plant with seven machines of this type. In the course of the next modernization step...

In the past 14 months, our Polish customer MPGK established a modern plant for the biological treatment of organic waste in Katowice (Poland). IFE supplied a waste screen and a Trisomat for the screening of MSW and C&I. At the same time, IFE equipped...

On November 9th and 10th the Canadian Waste and Recycling Expo took place in Toronto. The CWRE is the premier event for waste & recycling professionals in Canada. This year the show attracted more than 3,000 attendees and 300 exhibitors from across Canada, the United States and abroad...

IFE also shows a strong exhibition presence in late autumn and winter. On November 9th and 10th IFE Aufbereitungstechnik will be represented at the CWRE, the Canadian Waste & Recycling Expo, in Toronto. The trade fair brings together professionals from various sectors of the waste and recycling industry. Together with our Canadian sales partner EUROTECH Process, IFE presents its entire product range and addresses your specific applications. Visit our booth #1403! The last exhibition of the year...

Recently IFE Aufbereitungstechnik supplied a spiral elevator to a well-known recycling company in Germany. It is used for the vertical transport of electronic waste and was delivered in dust-proof design for this purpose. With a conveying height of 7m and a total height of 8.5m this spiral elevator is one of the highest IFE has ever built.

In mid-October IFE presented itself at the Pol-Eco-System 2016, the international trade fair for environmental technology and sustainable development in Pozna (Poland). 600 exhibitors from 25 countries presented their product innovations to an international specialist audience. With this remarkable number of exhibitors, the well-frequented Pol-Eco-System is one of the leading trade fairs in the recycling industry in Central and Eastern Europe. The IFE-booth was very well attended. The exhibited IFE-Sort...

A growing tendency can be observed in the waste sector to separate valuable materials such as copper or aluminium from fine materials. Recycling companies have to follow these market requirements. IFE Aufbereitungstechnik therefore enhanced its Stratos, the eccentric eddy current separator for the separation of finest non-ferrous metals. The modified machine is considerably stronger than the well-proven type and thus can separate even more fine aluminium, copper or brass parts form electronic scrap, industrial waste, aluminium slag or others.

We count on our loyal employees! On September 22nd IFE Aufbereitungstechnik celebrated the end of another successful financial year. The management board took this opportunity, to thank its long-standing employees for their loyalty to the company. Fifteen employees were honoured. We congratulate you all to your jubilees and look forward to many more years with you by our side!

With the RWM, the "Recycling and Waste Management Exhibition 2016", an exciting fair autumn started for IFE. England's leading trade fair for recycling and waste management took place from September 13th to 15th at the NEC Birmingham. Around 600 exhibitors presented their latest technologies and product innovations from the recycling sector to a broad audience of waste management specialists, public authorities and institutes. Apart from well-known exhibitors, the fair also offered various show highlights and successful networking events and thus attracted 13.000 visitors...

Around 138,000 visitors from more than 170 countries attended the 50th edition of the IFAT, the world's leading trade fair for water, sewage, waste and raw materials management in Munich, from May 30th to June 3rd, 2016.3,097 exhibitors from 59 countries presented their new products and innovations for the environmental technology sector on a trade fair area of 230,000 m.

From April 7th to 8th, the 60th Austrian foundry congress took place in Bad Ischl.This year's event was held under the slogan "Industry 4.0 - implementation in foundry. Interesting lectures and a comprehensive program led more than 280 participants from six different countries to Bad Ischl...

From April 2nd to 7th, 2016 the ISRI Congress (Institute of Scrap Recycling Industries) at the Mandalay Bay Hotel in Las Vegas, Nevada took place. In addition to the congress an exhibition for scrap recycling was held on April 5th and 6th...

This year IFE again was represented at the Save the Planet, the international exhibition and conference on energy efficiency and renewable energy in Sofia. The annual fair is marketplace for manufacturers, traders and service providers from the industries waste management, recycling and environment.The exhibitors had the chance...

Besides the optimization of the visual appearance, the IFE website is now optimized for all devices (tablets, smartphones) and therewith available without restrictions. Even a barrier-free use of the website is possible now...

All good things come to an end. After many years of faithful partnership we recently had to say goodbye to our representative Zbynek Gregor, who went into his well deserved retirement. For more than 20 years Mr. Gregor accompanied IFE - 20 years full of dedication and loyalty...

Recently, IFE put a semi-mobile fe/nf separator in operation. The roll-off tipper separation system has been developed by IFE and consists of a charging feeder, ferrous / non-ferrous separator, discharging belts and a control cabinet. The individual elements are mounted on a truck frame...

180 m of extra space for assembly could be created after relocating the technical design department. Our design department had to move to another venue due to spacial restrictions. By renovating this free area,...

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magnetic separators for waste and recycling industries

#2. Product Purification Product purification is the way to separate those impurities that resemble the product very closely in physical and chemical properties. Timber and glass are the waste products which are more suitable for recycling after the tramp metal has been removed.

Overbelt/suspension magnets, magnetic pulley and eddy current separators are the widely used metal separation equipment that is used in recycling and waste facilities to extract metal pieces from the products.

Magnetic Head Pulleys are specially designed to separate tramp metals like bucket teeth, steel, bore crowns, bar scrap, chains and tools. It is widely used in the recycling industry to remove steel from aluminium cans and many other ferrous contaminations like spikes, cans, nails, nuts etc. Magnetic Head Pulley is mostly used in wood, plastic, steel, paper, scrap yard, mining recycling, municipal recycling industries and many other recycling plants.

Eddy Current Separator is specially designed to help the recycling industry by separating non-ferrous metals like aluminium, brass, copper, lead, etc. Basically, it is used to remove metals based on a high conductivity-to-density ratio. The main thing to know about this machine is his robust construction with anti-vibration pads.

The powerful quality of magnets is used for the perfect and smooth separation for all industries. Eddy current separator has a capacity from 2MT/hr to 15MT/hr. It easily solves the problem of eliminating non-ferrous metals from municipal solid waste. By using this eddy current separator, recycling industries like plastic, rubber, glass, municipal solid waste, e-waste, pet etc. can take a huge advantage of it!

Jaykrishna Magnetics Pvt. Ltd. is the worlds most trusted magnetic separators manufacturing company. Weve developed a wide of magnetic separators for recycling and various other industries. Our high-intensity magnets are designed to extract the impurities from the recycling product stream.

If you are looking for the best magnetic separators in the market, then our magnetic separators are the best choice. Feel free to contact us on [email protected] for more detailed information or visit our website for wide product range www.jkmagnetic.com

Jaykrishna Magnetics Pvt. Ltd. is the leading manufacturer and exporter of Magnetic and Vibratory Equipments in India. We are established since 1978. The unique and premium structural design imparts quality and elegance to our products. Our focus is on continuously improving our process, service and products to exceed the benchmarks set by our competitors and offer better products to you.

tumble polishing

Over the years, I have been asked a kazillion questions about tumble polishing jewelry. One would think it's a pretty cut and dried task to tumble jewelry. However, there are some tips and techniques that I've learned over the years which may help give you better results from your rotary style tumbler without having to learn some things the hard way.

Why indeed! When I first started making wire jewelry, I didn't tumble it. But now I can't imagine NOT tumbling as part of the finishing process for my jewelry! Tumbling burnishes the soft metals like silver, gold and copper, making them shiny and polished looking. It also removes any excess patina residue or crud etc... thoroughly cleaning the items and softening any plier marks and metal burrs. It also helps to harden the metal, making it more durable and better able to hold its shape. Basically, you add stainless steel shot into your barrel, just enough water to cover the jewelry and a squirt of liquid dish soap. Put on the lids and let it go!

One pound of stainless steel shot is perfect for a 3 pound tumbler like a Lortone 3A or Chicago brand machine from Harbor Freight. The Lortone machines are known as the best. The 3A - 3 pound capacity tumblers average about $85 retail. Harbor Freight offers the same model of tumbler made in China for around $30. The HF tumblers are noisier and the belts don't hold up very well. I've replaced the belts in my HF tumblers with the much longer lasting Lortone ones. The Lortone belts for the 3A tumblers retail for less than $2 each. Tumblers are designed to run 24/7 for years. The motors of both brands of tumblers I own are working just fine after 5-6 years of hard use.

The HF brand tumblers have a very strong and unpleasant rubber odor that takes a couple of weeks to dissipate. It'll just about knock you over when you open the box, so consider yourself warned! :)

I also have some larger capacity tumblers with bigger barrel sizes like the Lortone 4C and the QT6. Because I make big and sometimes heavy jewelry and lots of choker-style necklaces, I needed the bigger barrels. However, a bigger barrel means more shot is necessary to get the best results. You can also get a double barrel tumbler, Lortone 33B or HF double barrel which look like two of the 3A styles put together. The HF tumbler is a great value for a small investment once you put a decent belt on it. If you have the means to start out with a Lortone, they are very nice machines.

Take extra care to keep the seal of the barrel and the lid dry before reloading your tumbler as some water qualities can corrode the aluminum under the rubber lid, causing the rubber seal to warp and leak. Also make sure you tighten that nut down on the lid. If you don't, you may enter the room where your tumbler is located only to find its contents all over your counter or floor. Not a great way to start your day! ;)

I prefer a stainless steel shot called a 'Jewelry Mix' which is made up of several different shapes of shot. Each of those shapes performs a different task in the tumbler to polish and clean the items in the barrel.

It is important to use stainless steel shot. At some point regular steel shot will rust...stainless steel shot will not. I've left the shot in my tumblers - I own four of them - for years and there's not a bit of rust in the lot of them! There are other media that some folks like to use to tumble polish jewelry and I'll talk about some of those later in this article.

Dawn dish washing liquid acts as an agent that holds all the yucky stuff (impurities etc...) that the stainless steel shot removes from the metal. When there are more impurities being removed than the dish soap can handle, it will happily re-deposit itself back onto the metal...hence, the greyish, bluish looking metal. You just need to tumble a bit longer with fresh solution. When your water is thick and black...time to change it! Sometimes when the items are really oxidized, they need to be taken out, re-buffed with the steel wool or 3M scrubby pad and then put into a fresh solution. Other times, you just need to change the solution. I know it sounds like a pain, but eventually you just learn by looking at it just what needs to be done.

You can then tumble some more...about 2 hours should do it with a fresh batch of clean water, clean shot, a freshly scrubbed or rinsed rubber barrel and a squirt of Dawn (about one teaspoon for a large tumbler, half that amount for a smaller 3 pound size.) If some of the components you use in your jewelry won't allow you to tumble for long periods of time, then you can use a polishing cloth that will remove the discoloration from your metal.

Tarnex will remove ALL oxidation from the silverplease don't use it on copperbut leaves the silver dull and sort of a whitish, yellowish yucky color. But...the oxidation is gone. :) You can then polish with a polishing cloth or re-tumble using fresh solution and it will shine right up! I think the most common problem with tumbling is that we don't change the solution often enough or we get in a hurry for the items to be done and don't leave them in long enough. Refreshing Bali beads, etc. usually takes about 30 minutes to one hour. Be sure to string any beads that have holes in them large enough for the shot to get into!! Otherwise you'll be spending oodles of time picking shot from the beads or just having to scrap them.

FOLKS, STRING THOSE LOOSE BEADS BEFORE YOU TUMBLE THEM!!! With today's silver prices, it's just too darned expensive not to...not to mention frustrating, heartbreaking, maddening, and the general good ol' stupid feeling. True gold-filled wire tumbles fine and should not have a coating that can come off like a plated wire will. Gold-filled is made by fusing a layer of karat gold to a suitable supporting metal. This is accomplished using very carefully controlled pressure, heat and time. The bond produced is permanent.

Tumbling is not a cure-all. It will not remove all the excess oxidation from LOS'd items. Not even if you let tumble for days! It will just polish them up. YOU must remove the excess oxidation BEFORE tumbling or afterward with elbow grease and a polishing cloth (or a flex-shaft and polishing wheel. :)) Sometimes, I tumble first, then oxidize, buff and it's done.

The de-burring solution for copper and silver is nice, but a word of caution on it. It is very, very concentrated. A little bit goes a loooong way. If you add too much to the barrel, it can actually make the copper come out dull and yucky feeling/looking. It does do a pretty good job of stripping away most the dark patina! I use it when tumbling jump rings and not much else.

Nothing porous like turquoise and pearls in the LOS. They will absorb the solution and get discolored. Soft and porous cannot be tumbled either. Now, lava rocks are porous and can handle the LOS AND the tumbling. While being porous, they are very hard natural volcanic glass. However, their holes are just the prefect size for plastic and stainless steel pellets to cram into. They don't come back out either! So they are a no-go for the tumbler! While there are some turquoises that will not be harmed by the process, you never know...so it's best not to chance it.

Also, tumble like with like...a few heavy bangles/bracelets or a bunch of earrings or ear wires, but not the light and heavy stuff together. Heavy items can damage delicate items. And don't overload your tumbler! That will stress out your motor and the belt. Best to tumble several smaller batches than try to stuff everything in at one time. You'll get a better finish if the shot can reach all surfaces of the items tumbling.

Yes and no. Tumbling gemstones with steel shot will not polish them. For those, you must use special polishing compounds. I recommend using a different barrel too! But polishing stones is a topic for another day.

I have found that Swarovski crystals do fine in the tumbler. Just make sure that you don't tumble heavy stuff with light, delicate things. To do so could damage the light stuff. Never tumble turquoise, pearls, dyed corals, or other soft gem materials. I have successfully tumbled the amethyst and smoky quartz gemstones that I use in many of my earrings.

I have plastic pellet shot that I sometimes use with really delicate items as it is not as harsh or heavy as stainless steel. I use the Dawn and water just like with the steel shot. However, this is really just to thoroughly clean the items and not to polish them. There are dry media like walnut shells, but I find it to be very messy and all those little walnut bits jam into every available hole! I have not had any success with rice either...it powders and, when wet, that powder turns to glue.

I hope you are not more confused than ever! I DO throw just about everything in my tumbler, but I am careful with the gemstones. Choose your tumbling 'partners' carefully. I don't tumble delicate gemstones and earrings with heavy bangles, etc. Earrings on a whole, come out just lovely from the tumbler. Have fun experimenting!

Are you sure that your silver colored bead is really Sterling? Sometimes 'silver' beads have a very low silver content, not qualifying them as true Sterling silver and whatever they may be alloyed with could be causing a problem.

Give the 'hematite' beads a Tarnex bath and rinse or burnish with 0000 fine steel wool. Wash the shot in your tumbler, give the rubber part just a rinse with sudsy water and re-tumble. Another possibility and where you could be picking up the contaminating culprit is in your water. Are you on a well? Try using a bottle of distilled water from the store.

Stainless steel shot can and will discolor glass lampwork beads that have been acid washed, giving them a slightly rough surface like sea glass. The steel shot transfers itself on the surface leaving little silvery streaks on the glass. Sometimes, I've had to re-etch the glass as they come out of the tumbler with little shiny silvery spots all over them! So now, I tumble the components ahead of time and don't put etched glass in with the stainless steel shot.

You can tumble it with plastic pellets with no problems, but this method really only works well to clean the pieces but does not polish the metal. If it really needs to tumble, the etched beads are usually OK with just a short time in the tumbler - like an hour.

Often, a new rubber barrel leaches a substance that will stain porous items like polymer clay a yucky, yellowish color ruining them as it does not come off. To avoid this, 'season' your tumbler barrel by using it with metal and glass items for a few weeks until the leaching stops. Your barrel will then be safe for tumbling the PC. You can always test the barrel first by adding a white test bead and tumbling it for 4-6 hours. If it comes out white, you're good to go! This is more of a problem with the HF brand.

You could be just scrubbing the rubber right off! LOL The small black rubber particles will be held in suspension by the dish soap and should not harm or discolor your jewelry. But seriously, please don't scrub so hard as to damage your rubber barrel! It is important to thoroughly rinse the pieces you've oxidized with Liver-Of-Sulfur and to wash your shot. This helps make sure no residual LOS is being added to and built up in your tumbler. To make certain you stop the oxidizing process, do the following steps.

conveyor chute lining | chute and skirt lining | conveyor skirt lining | asgco

Our Mid Atlantic division is the leading supplier of conveyors and bulk material handling products & services in the Mid-Atlantic region. From conveyor belting, idlers, pulleys, power transmission products, wear parts and screens to complete turnekey systems, ASGCO will handle any of your conveying and bulk material handling needs.

Our Complete Conveyor Solutions division is a manufacturer of conveyor products and equipment, along with conveyor engineering services, provided through our partnered network of servicing distributors and original equipment manufacturers (oems) around the globe.

ASGCO Steel Fabrication division is a full-service steel fabrication, contract manufacturing, machining, welding and finishing facility that has the ability to manufacture simple parts to complete assemblies to complex print-to-build projects for Original Equipment Manufacturers (OEMs) and industrial customers.

ASGCOs Chute Linings and Skirt Liners are designed to be an integral part of a conveyor system. Our pre-engineered chute lining protects and cushions the chute from the material being handled; Skirt Liners prevents fugitive materials from escaping and damaging the conveyor loading areas. We can build, design, fabricate and install chutes, and also repair and re-align existing chutes.

Combining the right liner with the correct chute design improves overall system efficiency and maximizes material transfer, promoting efficient flow, dust suppression and reduced buildup inside the chute.

Armorite Skirt Liners protect your skirtboard and provide a significantly longer wear life than currently used skirt liners. Armorite Wear Plates present a very cost effective method of extending wear life in chutes, hoppers, bins, impact walls and screen plates.

Armorite is an extremely hard, laminated bi-metalic, wear resistant composite, which has a normal hardness of 700 BHN (63Rc) produced by combining a highly alloyed chromium-molybdenum white iron (to AS 2027 15/3 Cr/Mo) and metallurgically bonding it to a mild thick steel backing plate. The resultant bond possesses high shear strength of over 250 Mpa and will not separate.

Transfer point design, fabrication and installations utilizing ASGCOs 3-DEM chute analysis program (Discrete Element Methods) is a revolutionary way to handle granular and particulate material by streamlining the process from the point where material leaves the head pulley until it is deposited onto the receiving conveyor for a more deliberate control of the material as it flows from one conveyor to another. The performance of transfer chutes is an essential part to the productivity of the conveyor belt systems in the bulk solids industry.

These techniques are easily applied to both existing and new installations, resulting in significant cost improvements and system efficiencies. Combined with our conveyor and material handling knowledge, engineering capabilities and complete turn-key installation services, we are able to make transfer point problems a thing of the past.

The laser technology is more accurate than traditional methods because it looks at thousands of points along the clearance plane, not just a few sample points. The ultra-portable Point Cloud Laser Scannerenables fast, straightforward, and yet accurate measurements of facades, complex structures, production and supply facilities, accident sites, and large-volume components.

ASGCO Point Cloud Laser Scanner delivers extraordinary color overlays for scanned point clouds. This improves the visualization of important details on site. Our system can capture over 1 million points per second and can scan through 360 horizontally and vertically.

gold processing,extraction,smelting plant design, equipment for sale | prominer (shanghai) mining technology co.,ltd

Prominer maintains a team of senior gold processing engineers with expertise and global experience. These gold professionals are specifically in gold processing through various beneficiation technologies, for gold ore of different characteristics, such as flotation, cyanide leaching, gravity separation, etc., to achieve the processing plant of optimal and cost-efficient process designs.

Based on abundant experiences on gold mining project, Prominer helps clients to get higher yield & recovery rate with lower running cost and pays more attention on environmental protection. Prominer supplies customized solution for different types of gold ore. General processing technologies for gold ore are summarized as below:

For alluvial gold, also called sand gold, gravel gold, placer gold or river gold, gravity separation is suitable. This type of gold contains mainly free gold blended with the sand. Under this circumstance, the technology is to wash away the mud and sieve out the big size stone first with the trommel screen, and then using centrifugal concentrator, shaking table as well as gold carpet to separate the free gold from the stone sands.

CIL is mainly for processing the oxide type gold ore if the recovery rate is not high or much gold is still left by using otation and/ or gravity circuits. Slurry, containing uncovered gold from primary circuits, is pumped directly to the thickener to adjust the slurry density. Then it is pumped to leaching plant and dissolved in aerated sodium cyanide solution. The solubilized gold is simultaneously adsorbed directly into coarse granules of activated carbon, and it is called Carbon-In-Leaching process (CIL).

Heap leaching is always the first choice to process low grade ore easy to leaching. Based on the leaching test, the gold ore will be crushed to the determined particle size and then sent to the dump area. If the content of clay and solid is high, to improve the leaching efficiency, the agglomeration shall be considered. By using the cement, lime and cyanide solution, the small particles would be stuck to big lumps. It makes the cyanide solution much easier penetrating and heap more stable. After sufficient leaching, the pregnant solution will be pumped to the carbon adsorption column for catching the free gold. The barren liquid will be pumped to the cyanide solution pond for recycle usage.

The loaded carbon is treated at high temperature to elute the adsorbed gold into the solution once again. The gold-rich eluate is fed into an electrowinning circuit where gold and other metals are plated onto cathodes of steel wool. The loaded steel wool is pretreated by calcination before mixing with uxes and melting. Finally, the melt is poured into a cascade of molds where gold is separated from the slag to gold bullion.

Prominer has been devoted to mineral processing industry for decades and specializes in mineral upgrading and deep processing. With expertise in the fields of mineral project development, mining, test study, engineering, technological processing.