mechanical flotation machine

flotation machines

As pneumatic and froth separation devices are not commonly used in industry today, no further discussion about them will be given in this module. The mechanical machine is dearly the most common type of flotation machine currently used in industry, followed by the column machine which has recently experienced a rapid growth.

A mechanical machine consists of a mechanically driven impeller that disperses air into the agitated pulp. In normal practice this machine appears as a long tank-like vessel having a number of impellers in series. Mechanical machines can have open flow of pulp between the impellers or can be of cell-to-cell design with weirs between them. Below is a typical bank of flotation cells used in industrial practice.

The procedure by which air is introduced into a mechanical machine falls into two broad categories: self-aerating, where the machine uses the depression created by the impeller to induce air, and supercharged, where air is generated from an external blower. The incoming feed to the mechanical flotation machine is usually introduced in the lower portion of the machine. At the very below is shown a typical flotation cell of each air delivery type (Agitair & Denver)

The most rapidly growing class of flotation machine is the column machine, which is, as its name implies, a vessel having a large height-to-diameter ratio (from 5 to 20) in contrast tomechanical cells. This type of machine provides a counter-current flow of air bubbles and slurry with a long contact time and plenty of wash water. As might be expected, the major advantage of such a machine is the high separation grade that can be achieved, so that column cells are often used as a final concentrate cleaning step. Special care has to be exercised in the generation of fine air bubbles and the control of the feed rate to the column cell for such cells to be effective. Column cell use is often of limited value in the recovery of relatively coarse valuable particles; because of the long lifting distances involved, the bubbles can not carry large particles all the way to the top of the cell.

Probably the most significant area of change in mechanical flotation cell design has been the dramatic increase in machine cell volume with a single impeller. The idea behind this approach is that as machine size increases (assuming no loss of recovery performance with the larger machines), both plant capital and operating cost per unit of throughput decrease. In certain industrial applications today, cells of even a thousand cubic meters in volume (a large swimming pool) are being used effectively.

The throughput capabilities of various cell designs will vary with the flotation machines residence time and pulp density The number of cells required for a given operation is determined from standard engineering, mass balance calculations. In the design of a new plant, the characterization of each cells volume and flotation efficiency is generally calculated from data gathered on a laboratory scale flotation using the same type of equipment for the same material mixture in question. This procedure is then followed by the application of semi-empirically derived scale-up factors. Research work is currently under way to improve the understanding and performance of commercial flotation cells.

Currently, flotation cell design is primarily a proprietary material of the various cell manufacturers. Flotation plants are built in multiple cell configurations (called banks), and the flow through the various banks is adjusted in order to optimize plant recovery of the valuable as well as the grade of the total recovered mass from flotation. Up above is a typical flotation bank scheme. The total layout of a given flotation plant (including all of the various banks) operating on a given feed is called a flotation circuit.

The application of the air-lift to flotation is not new, but the first attempts to make use of the principle were not successful because the degree of agitation in the machine was insufficient to enable the heavy oils then in use as collecting reagents to function effectively. The advent of chemical promoters, however, made agitation of secondary and aeration of primary importance, with the result that the application of the air-lift principle became practicable and led to the introduction of the Forrester and the Hunt matless machines. South western Engineering Corporation are the owners in most countries of the rights to license and manufacture these and other types operating on the air-lift principle, and they have developed a machine based chiefly on the Welsh and Hunt patents which may be considered as representative of the type that is now most commonly used.

The Southwestern Air-Lift Machine, as it is called, consists of a V-shaped wood or steel trough of any length but of the standard cross-section shown in Fig. 40, the area of which is 9.85 sq. ft. and the interior depth 36 in. Low- pressure air is delivered from a blower through a main supply pipe to an air-pipe or header which runs longitudinally over the top of the machine. The air enters the trough itself through a seriesof vertical down-pipes , which are screwed into sockets welded tothe underside of the header at 4-in. intervals along its length and are open at their lower ends. They are from to 1 in. in diameter for roughing machines and from to in. for cleaners, and they reach to within 6 in. of the bottom. The air-lift chamber is formed by two vertical partitions, one on each side of the line of down-pipes, both of which extend from one end of the trough to the other, forming a compartment 6 in. wide. The lower edges of the partitions are an inch or two above the ends of the down-pipes and their upper edges are about level with the froth overflow lips at each side of the machine. A few inches above the top of the air-lift chamber is a deflector cap which serves to direct the rising pulp outwards and downwards against two vertical baffles. These extend the length of the trough parallel to and outside the partitions, their loweredges being several inches below the normal pulp level. The spacebetween the baffles and the sides of the machine forms two spitzkasten- shaped zones of quiet settlement where the froth collects.

The feed enters near the bottom of one end of machine and the tailing is discharged over an adjustable weir at the other end. The air, issuing in a continuous stream from the open ends of the down-pipes, carries the pulp up the central chamber on the principle of an air-lift pump. The air is subdivided into minute bubbles and more completely mixed with the pulp as the rising mass hits the cap at the top and is deflected and cascaded on to the baffles at each side, which direct it downwards, distributing the bubbles evenly throughout the pulp in the body of the machine and giving them ample opportunity to collect a coating of mineral. Rising under their own buoyancy, the bubbles enter the spitzkasten zones, up which they travel without interference, dropping most of the gangue particles mechanically entangled between them as they ascend. They collect on the surface of the pulp at the top as a mineralized froth, which is voluminous enough to pass over the lip into the concentrate launders without the need of scrapers. The pulp, on the other hand, continues its downward passage and enters the air-lift chamber again. In this way a continuous circulation of the pulp is maintained, its course through the machine being more or less in the form of a double spiral.

The aeration is generally controlled by a single valve in the header of each machine, but for selective flotation the machine is sometimes divided by transverse partitions into sections 4 ft. long, the header over each section being provided with a separate air-valve. The depth of the froth is regulated by means of the adjustable gate of the tailing weir. If difficulty is likely to be experienced in making a clean tailing with the normal amount of aeration, it is preferable to use two machines. The second one is run as a scavenger with an excess of air as compared with normal requirements, the low-grade froth so produced being pumped back to the head of the primary or roughing machine, in which the aeration is more normal in order that a comparatively clean concentrate may be produced. It is often possible to take a concentrate off the first few feet of the rougher rich enough to be sent to the filters as a finished product, the froth from the rest of the machine being pumped back to the head. When this method of flotation is adopted, it is an advantage to have the header divided into sections, each with its own valve, so that the aeration can be varied along the length of the machine. By increasing the volume of air at the discharge end the froth can be given a slight flow towards the head of the machine, with the result that the minerals are concentrated there to the exclusion of partially floatable gangue which might otherwise enter any bubbles not fully loaded with mineral.

If the froth from the feed end of the rougher is not of high enough grade, it must be re-treated in a separate cleaning machine, the length of which usually varies from one-quarter to one-half of the total length ofthe roughing and scavenging machines according to the amount of concentrate to be handled. Should still further cleaning be necessary, it is performed in a recleaner, which is generally of the same length as the cleaner. The tailings from these operations are often, but not necessarily, returned to the head of the rougher.

It is usual to prepare the pulp for flotation by adding the reagents to the grinding circuit or in a conditioning tank ahead of the flotation section, but soluble frothers such as pine oil and quick-acting promoters such as the xanthates can be added at the head of the machine if desired, since the air-lift provides enough agitation to emulsify and distribute them throughout the pulp. It is not as a rule advisable to introduce reagents into the air-lift chamber itself ; should it be necessary to do so to obtain a satisfactory recovery of the minerals, it is best to employ separate roughing and scavenging machines and to make the extra additions at the head of the scavenger.

Southwestern Air-Lift Machines are made of standard cross-section, as already stated, and in a series of lengths ranging, for ordinary purposes, from 4 to 48 ft. There is no limit to the possible length, however, and 100-ft. machines are in actual use. The tonnage capacities under different conditions will be found in Table 26. The pressure of air needed at the machine is from 1.6 to 1.7 lb. per square inch, which under normal conditions requires a pressure of about 2 lb. per square inch at the blower. It is usual to allow 75 to 100 cu. ft. of free air per minute at this pressure per foot of rougher and 45 to 70 cu. ft. per minute per foot of cleaner and recleaner. From these figures the approximate volume of air required for a machine or machines of any given length can be calculated. The power necessary to supply the air can then be found from Table 30.

The Callow Cell consists of a shallow horizontal trough, the bottom of which is covered with a porous medium, usually termed a blanket, consisting of a few layers of canvas or of a sheet of perforated rubber. Air is introduced at low pressure under the blanket, and, in passing through it, is split up into minute bubbles, which rise through the pulp in the cell, collecting a coating of mineral in the process.

Fig. 41 shows a section of the type of cell commonly employed. Its width is usually from 24 to 36 in., and its interior depth from 18 to 22 in. measured from the overflow lip ; the length varies according to requirements and is generally a multiple of the width. On the bottom are placed, side by side, the square open-topped cast-iron blanket frames or pans . The blanket covering the top of each pan is securely held in place by flat iron strips bolted round the edges, while one or two pipe grid-bars across the top prevent it from bulging. This arrangement allows a blanket to be changed in a few minutes should it becomedamaged. The air inlet to each pan projects through the bottom of the cell and is connected by a pipe and regulating valve to a header, which is provided with a main control valve.

The pulp enters one end of the cell through a feed opening and is discharged over an adjustable weir at the other end. There is no agitation, but the continuously rising stream of air bubbles keeps the particles of ore in suspension and induces a certain amount of circulation as the pulp passes along the cell. In this way the minerals are given many chances of becoming attached to the bubbles and thus of being carried over into the concentrate launder. The froth that forms on the surfaceof the pulp, usually to a depth of 8 to 10 inches, is voluminous enough to overflow the lips on each side of the cell without the use of mechanical scrapers.

For estimating purposes the average capacity of a Callow Cell may be taken as 2.5 tons of feed per square foot of blanket area per 24 hours and the air consumption as 9 cu. ft. of free air per minute per square foot of blanket at a pressure of 4 lb. per sq. in. A greater pressure is likely to be required if the blankets become blinded .

The Callow Cell has proved satisfactory for many types of ores, but it has the disadvantage that coarse or heavy sand settles on the blankets, and can only be kept in motion by flogging the latter with short rubber-buffered poles. Moreover, if lime is employed in the circuit, the blankets become impregnated and clogged with calcium carbonate, which necessitates periodical acid treatment for its removal. The use of perforated rubber sheets in place of canvas in the Callow Cell mitigates without entirely curing these difficulties, which at one time were thought to be inherent in the use of a porous medium. They have been overcome, however, by the development of the Callow-Maclntosh Machine.

The Callow-Maclntosh, or the Macintosh Machine, consists of a shallow trough or cell at the bottom of which is a hollow revolving rotor covered with a porous medium. Fig. 42 shows its construction. The pulp enters through a feed opening at one end, and is discharged at the other in much the same way as in a Callow Cell. The rotor, made of seamless steel tubing with a cast-steel ring welded in each end, is perforated with -in. holes at 7-in. centres; it is about 8 in. shorter than the length of the cell and is usually 9 in. in diameter. Its weight is taken by two hollow shafts, each fitted with a flange, which are bolted to the ends of the rotor by means of four studs. This method of attachment enables the rotor to be changed and a new one inserted with little loss of time, usually not more than 15 minutes. The shafts project through the ends of this cell and are supported on self-aligning ball and socket bearings outside, so placed that the rotor itself is a few inches clear of the bottom of the trough. A rubber gasket, shown in Fig. 43, seals the opening at each end by simple pressure on a cone-faced disc mounted on the shaft. The joint is not completely watertight and a slight leakage takes place through it at the rate of about one quart per minute. At the discharge end this escaping pulp gravitates to the tailing launder, while at the feed end it is usually led to one of the pumps returning a middling product to the roughing circuit. The gasket is preferable to a stuffing-box, as it contains no grease and requires no gland water.

The rotor covering consists of a canvas sock or of a single sheet of perforated rubber. The latter is now far more commonly employed, since it lasts five times as long as the other, its life generally exceeding 18 months ; moreover it seldom becomes blinded withcalcium carbonate, and requires an air pressure of only 2 lb. per square inch instead of the 3-lb. pressure needed for canvas. The rubber sheets are made of pure gum about 5/64 in. thick with 225 holes per sq. in., the holes being made so as to allow the air to pass through while preventing the percolation of the pulp into therotor in the event of a temporary shut-down. Two scraper bars of angle iron, 1 by 1 in., are bolted to opposite sides of the rotor on the top of the covering. They project 2 in. beyond the ends of the rotor, and their purpose is to keep in circulation any sand that settles on the bottom of the cell, at the same timeprotecting the porous medium from undue wear by contact withsuch material. Air is introduced into the rotor through one or bothof the hollow shafts, which are connected by special inlet joints with themain supply. When both ends are employed for the admission of air,the rotor is usually divided into two sections by a central partitionto enable each half to be controlled separately. The rotor is driven ata speed of about 15 r.p.m. by an individual motor connected with theshaft at one end of the cell; either a worm drive directly coupled to themotor or a chain drive coupled to the motor through a speed reducercan be employed.

The principle on which theCallow-Maclntosh Machine worksis very similar to that of a CallowCell. The air bubbles actuallyissue from the top of the rotor,where the hydraulic pressure islowest, and spread out as theyrise, their distribution throughthe pulp being quite as even andeffective as when a flat blanket isused. The cell never needs flogging since the movementof the rotor prevents sand fromsettling on it, and the scraperbars keep in circulation theheavy particles that would otherwise settle on the bottom. Themachine can, if necessary, handle ore as coarse as 20 mesh at a W/Sratio of 1/1 without choking.

The control of a pneumatic cell is different from that of a machine of the mechanically agitated type, of which each cell is capable of performing the function of a high-speed conditioner. Little conditioning takes place once the pulp has entered a pneumatic cell, and provision must therefore be made for its proper preparation when employing heavy oils or chemical reagents which need a long contact period. The froth is usually maintained at a depth of 8 to 10 in., giving an effective pulp depth of 18 to 20 in. The very large volume of air bubbles released enables flotation to be effected more rapidly than in any other type of machine, the actual time required depending mostly on the degree to which the minerals have been rendered floatable. The upward stream of bubbles is so voluminous that, under ordinary conditions, the froth overflows the lips on both sides of the cell without the need of scrapers. For the same reason a considerable quantity of gangue is often carried over into the concentrate launder by mechanical entanglement with the bubbles, and one, sometimes two, subsequent cleaning operations are generally necessary in consequence. This, however, is by no means therule ; a concentrate of high enough grade to be sent to the filtering section as a finished product can sometimes be made in a single rougher- cleaner cell. When the Callow-Macintosh Machine is run in this way (counter-current operation) a partitioned rotor is employed, since, by increasing the volume of air at the tailing-discharge end, the froth can be made to flow towards the head of the cell with the result that the minerals are concentrated there to the exclusion of gangue particles. The same effect can be obtained in a Callow Cell by regulating the admission of air to the individual pans in a similar way. If is often the practice, especially in counter-current operation, for the rougher to be followed by a scavenging cell, which is run with an excess of air as compared with the former, the froth being returned to the head of the first cell.

Callow-Macintosh Machines are made in lengths of 10, 15, and 20 ft. and in widths of 24, 30, and 36 in. with a rotor 9 in. in diameter. The vertical distance from the centre-line of the rotor to the overflow lip is about 24 in. The design of the machine, however, lends itself to the construction of larger sizes for big scale operationsi.e., up to a 30-ft. cell 48 in. wide with one or two 9-in. rotors. The 30- and 36-in. cells are sometimes fitted with rotors up to 15 in. in diameter to meet special requirements.

The capacity of the standard machine varies considerably according to the grade and character of the ore. The average capacity of a rougher or rougher-cleaner cell is from 8 to 12 tons of dry feed per foot of rotor length per 24 hours. When cleaning is practised, the tonnage per foot of total rotor length (roughers, scavengers, and cleaners) may vary from 4 tons for a slow-floating ore needing double cleaning to 10 tons for an easily-floated ore with single cleaning, the average being about 6 tons per foot of total rotor length. The cleaning section usually amounts to between one-quarter and one-half of the combined length of the roughing and scavenging cells. The width of cell employed depends on the character of the ore, the time of treatment, and the tonnage.

The quantity of air necessary varies from 5 to 7 cu. ft. per minute per square foot of aerating surface at 2- to 2-lb. pressurethat is, from 12 to 16.5 cu. ft. per minute per linear foot of rotor. With a Roots type blower the power consumption in respect of the air supply is about 12 h.p. per 1,000 cu. ft. of free air per minute at a pressure of 2 lb. per square inch. The power needed to turn the rotor averages 0.5 h.p.

flotation machine - an overview | sciencedirect topics

Industrial flotation machines can be divided into four classes: (1) mechanical, (2) pneumatic, (3) froth separation, and (4) column. The mechanical machine is clearly the most common type of flotation machine in industrial use today, followed by the rapid growth of the column machine. Mechanical machines consist of a mechanically driven impeller, which disperses air into the agitated pulp. In normal practice, this machine appears as a vessel having a number of impellers in series. Mechanical machines can have open flow of pulp between each impeller or are of cell-to-cell designs which have weirs between each impeller. The procedure by which air is introduced into a mechanical machine falls into two broad categories: self-aerating, where the machine uses the depression created by the impeller to induce air, and supercharged, where air is generated from an external blower. The incoming slurry feed to the mechanical flotation machine is introduced usually in the lower portion of the machine.Figure 7 shows a typical industrial flotation cell of each air delivery type.

The most rapidly growing class of flotation machine is the column machine, which is, as its name implies, a vessel having a large height-to-diameter ratio (from 5 to 20) in contrast to mechanical cells. The mechanism behind this machine to is provide a countercurrent flow of air bubbles and slurry with a long contact time and plenty of wash water. As might be expected, the major advantage of such a machine is the high separation grade that can be achieved, so that column cells are often used as a final concentrate cleaning step. Special care has to be exercised in the generation of fine air bubbles and controlling the feed rate to column cells.

Good mixing of pulp. To be effective, a flotation machine should maintain all particles uniformly in suspension within the pulp, including those of relatively high density and/or size. Good mixing of pulp is required for maximizing bubble-particle collision frequency.

Appropriate aeration and dispersion of fine air bubbles. An important requirement of any flotation machine is the ability to provide uniform aeration throughout as large a volume of the machine as is possible. In addition, the size distribution of the air bubbles generated by the machine is also important, but experience has shown that the proper choice of frother type and dosage generally dominates the bubble size distributions being produced.

Sufficient control of pulp agitation in the froth zone. As mentioned earlier, good mixing in the machine is important; however, equally important is that near and in the actual froth bed at the top of the machine, sufficiently smooth or quiescent pulp conditions must be maintained to ensure suspension of hydrophobed (collector coated) particles.

Efficient mass flow-mechanisms. It is also necessary in any flotation machine that appropriate provisions be made for feeding pulp into the machine and also for the efficient transport of froth concentrate and tailing slurry out of the machine.

Probably the most significant area of change in mechanical flotation machine design has been the dramatic increase in machine size. This is typified by the data ofFig. 8, which shows the increase in machine (cell) volume size that has occurred with a commonly used cell manufactured by Wemco. The idea behind this approach is that as machine size increases, both plant capital and operating costs per unit of throughput decrease.

The throughput capabilities of various cell designs will vary with flotation residence time and pulp density. The number of cells required for a given operation is determined from standard engineering mass balance calculations. In the design of a new plant, the characterization of each cell's volume and flotation efficiency is generally calculated from performing a laboratory-scale flotation on the same type of equipment on the ore in question, followed by the application of empirically derived design (scale-up) factors. Research work is currently under way to improve the understanding and performance of commercial flotation cells. Currently, flotation-cell design is primarily a proprietary function of the various cell manufacturers.

Flotation plants are built in multiple cell configurations (called banks), and the flow through various banks is adjusted in order to optimize plant recovery of the valuable as well as the valuable grade of the total recovered mass from flotation. This recovery vs grade trade-off is economically important in flotation, as increased recovery of the valuable is associated with decreased grade. For example, a 95% recovery of copper in the feed ore might give a concentrate grade of 18% Cu in the total recovered mass, while 80% Cu recovery might give a grade of 25% in the concentrate. Obviously, the higher the valuable recovery is, the higher the potential income, but if this higher recovery requires a great deal more grinding and/or expensive downstream processing (including further flotation) in order to upgrade the concentrate for metal refining such as smelting, the increase in potential recovery income may actually cause a net loss of total income. This grade-recovery optimization is generally worked out by individual flotation operators in each plant (and each mineral) and sets the operating philosophy of that plant.Figure 9 shows a typical industrial recovery vs grade trade-off curve for a copper sulfide ore containing pyrite. The higher the copper recovery is, the greater the amount of undesired pyrite contained in the concentrate.

The various banks of flotation cells in an industrial plant are given special names to denote the particular purpose of the banks. The rougher bank is the first group of cells that the pulp sees after size reduction. The goal of the roughers is to produce a concentrate with as high a recovery of valuable as possible with generally low grade of the valuable. The rejected gangue material from any bank of cells is commonly denoted as the tails or tailings. Usually, rougher tails are discarded so that valuable mineral not recovered in the rougher bank is lost. The concentrate of the rougher bank can be further concentrated, sometimes after additional grinding, in banks of cells called cleaners or recleaners. The tailings from the cleaners or recleaners can be recirculated to a bank of cells known as scavengers in order not to lose any valuable material in the upgrading process. Various banks of cells are also sometimes known by the particle size of the particular pulps being floated. Coarse particles, fine or slime particles, and middle-sized particles, denoted as middlings, can all be treated in separate banks.

As to overall capacities of flotation plants, the range is quite variable, depending on the type and value of the mineral being processed, the amount of valuable mineral in the feed ore to flotation, the degree and cost of size reduction involved, and the relative response of the valuable(s) to the flotation process. Smaller plants ranging in size from 500 to 5000 metric tons of feed per day are common, with feed materials having high amounts of valuable per ton of feed ore (>40%), such as coal, phosphate, and oxide ores. On the other hand, the sulfide minerals that are typically a small percentage of the ore (<10% and often less than 1%) require much greater capacity in order to achieve a reasonable economic return on investment. Thus, typical copper sulfide plants have capacities in the range of 20,000 to more than 60,000 metric tons of feed ore per day.

Conventional flotation machines house two functions in a single vessel: an intense mixing region where bubbleparticle collision and attachment occurs, and a quiescent region where the bubbleparticle aggregates separate from the slurry. The reactor/separator machines decouple these functions into two separate (or sometimes more) compartments. The cells are typically considered high-intensity machines due to the turbulent mixing in the reactor (see Section 12.9.5). The role of the separator is to allow sufficient time for mineralized bubbles to separate from the tailing stream which generally requires relatively short residence time (when compared to mechanical cells or columns).

Some of the earliest machine designs were of the reactor/separator-type. Figure 12.80 shows a design from a patent by Hebbard (1913). Feed slurry was mixed with entrained air in an agitation box (reactor) and flowed into the separation vessel where froth was collected as overflow. The design would be the basis for the Minerals Separation Corporation standard machine and early flotation cells used in the United States (Lynch et al., 2010).

The Davcra cell (Figure 12.81) was developed in the 1960s and is considered to be the first high-intensity machine. The cell could be thought of as a column or reactor/separator device. Air and feed slurry are contacted and injected into the tank through a cyclone-type dispersion nozzle, the energy of the jet of pulp being dissipated against a vertical baffle. Dispersion of air and collection of particles by bubbles occurs in the highly agitated region of the tank, confined by the baffle. The pulp flows over the baffle into a quiescent region designed for bubblepulp disengagement. Although not widely used, Davcra cells replaced some mechanical cleaner machines at Chambishi copper mine in Zambia, with reported lower operating costs, reduced floor area, and improved metallurgical performance.

Several attempts have been made to develop more compact column-type devices, the Jameson cell (Jameson, 1990; Kennedy, 1990; Cowburn et al., 2005) being a successful example (Figure 12.82). The Jameson cell was developed in the 1980s jointly by Mount Isa Mines Ltd and the University of Newcastle, Australia. The cell was first installed for cleaning duties in base metal operations (Clayton et al., 1991; Harbort et al., 1994), but it has also found use in coal plants and in roughing and preconcentrating duties. The original patent refers to the Jameson cell as a column method, but it can also be considered a reactor/separator machine: contact between the feed and the air stream is made using a plunging slurry jet in a vertical downcomer (the reactor), and the airslurry mixture flows downwards to discharge and disengage into a shallow pool of pulp in the bottom of a short cylindrical tank (the separator). The disengaged bubbles rise to the top of the tank to overflow into a concentrate launder, while the tails are discharged from the bottom of the vessel. Air is self-aspirated (entrained) by the action of the plunging jet. The air rate is influenced by jet velocity and slurry density and level in the separator chamber.

The Jameson cell has been widely used in the coal industry in Australia since the 1990s. Figure 12.83 shows a typical cell layout where fine coal slurry feeds a central distributor which splits the stream to the downcomers. Clean coal is seen overflowing as concentrate from the separation vessel. The major advantage of the cell in this application is the ability to produce clean concentrates in one stage of operation by reducing entrainment, especially when wash water is used. It also has a novel application in copper solvent extraction/electrowinning circuits, where it is used to recover entrained organic droplets from electrolyte (Miller and Readett, 1992).

The Contact cell (Figure 12.84) was developed in the 1990s in Canada. The feed slurry is placed in direct contact with pressurized air in an external contactor which comprises a draft tube and an orifice plate. The slurryair mixture is fed from the contactor to the column-type separation vessel, where mineralized bubbles rise to form froth. Contact cells employ froth washing similar to conventional flotation columns and Jameson cells. Contact cells have been implemented in operations in North America, Africa, and Europe.

The IMHOFLOT V-Cell (Figure 12.85(a)) was developed in the 19801990s and evolved from earlier designs developed in Germany in the 19601970s (Imhof et al., 2005; Lynch et al., 2010). Conditioned feed pulp is mixed with air in an external self-aeration unit above the flotation cell. The airslurry mixture descends a downcomer pipe and is introduced to the separation vessel via a distributor box and ring pipe with nozzles that redirect the flow upward in the cell. The separation vessel is fitted with an adjustable froth crowding cone which can be used to control mass pull. The concentrate overflows to an external froth launder, while the tailings stream exits at the base of the separation vessel. The V-Cell has been used to float sulfide and oxide ores with the largest operation being an iron ore application (Imhof et al., 2005).

The IMHOFLOT G-Cell (Figure 12.85(b)) was introduced in 2001 and employs the same external self-aerating unit as the V-Cell. The airslurry mixture which exits the aeration unit is fed to an external distributor box (located above the separation vessel) where pulp is split and fed to the separation vessel tangentially via feed pipes. The cell is unusual as an internal launder located at the center of the vessel collects froth. The centrifugal motion of the slurry enhances froth separation with residence times being ca. 30s.

The Staged Flotation Reactor (SFR) (Figure 12.86) is a recent development in the minerals industry. By sequencing the three processesparticle collection, bubble/slurry disengagement, and froth recoveryand assigning each to a purpose-built chamber, the SFR aims to optimize each of the three processes independently.

The SFR incorporates an agitator in the first (collection) chamber designed to provide high energy intensity (kWm3) and induce multiple particle passes through the high shear impeller zone, hence giving high collection efficiency. Slurry flows by gravity through the reactor stages, that is, there is no need to apply agitation to suspend solids, only for particle collection. As such, impeller speed can be adjusted online in correlation with desired recovery without sanding. The second tank is designed to deaerate the slurry (bubble disengagement) and rapidly recover froth to the launder without dropback. The froth recovery unit is tailored for use of wash water and for high solids flux. Efficient particle collection and high froth recovery translate into fewer, smaller cells, resulting in a smaller footprint and building height, with lower power consumption, and the potential for good selectivity in both roughing and cleaning applications.

Induced air flotation machines have gained a degree of popularity within certain sections of the minerals processing industry because of their ability to produce small bubbles at relatively high energy efficiency. The most common of such machines is the Jameson Cell. A downcomer protrudes out of the bubbly liquid in which is housed a plunging jet. Because this jet is at high velocity the pressure within the downcomer is low due to the Bernoulli equation, and air is induced into the downcomer creating a plume of bubbles within the liquid, which rise to form a foam. There are major problems with operating Jameson Cells because their high demand for surfactant causes downstream residual frother issues. (It is noted, as an aside, that frother strippers are being developed to remove residual frother in flotation circuits, and these are identical to foam fractionation units.) Notwithstanding that Jameson Cell technology has failed to live up to its promise, it has been successfully used as a pilot-scale foam reactor to effect the autothermal thermophilic aerobic digestion (ATAD) of high strength wastewater sludge produced at a chicken processing factory. The advantage that induced gas systems have over alternative pneumatic foam systems is their very high gasliquid surface area per unit volume of foam due to their small bubbles. This feature of the foams would also be an advantage in foam fractionation because it creates high flux of gasliquid surface. However, to the authors knowledge, no attempt has ever been made to use induced gas systems as foam fractionators.

The Denver DR flotation machine, which is an example of a typical froth flotation unit used in the mining industry, is illustrated in Figure 1.47. The pulp is introduced through a feed box and is distributed over the entire width of the first cell. Circulation of the pulp through each cell is such that, as the pulp comes into contact with the impeller, it is subjected to intense agitation and aeration. Low pressure air for this purpose is introduced down the standpipe surrounding the shaft and is thoroughly disseminated throughout the pulp in the form of minute bubbles when it leaves the impeller/diffuser zone, thus assuring maximum contact with the solids, as shown in Figure 1.47. Each unit is suspended in an essentially open trough and generates a ring doughnut circulation pattern, with the liquid being discharged radially from the impeller, through the diffuser, across the base of the tank, and then rising vertically as it returns to the eye of the impeller through the recirculation well. This design gives strong vertical flows in the base zone of the tank in order to suspend coarse solids and, by recirculation through the well, isolates the upper zone which remains relatively quiescent.

Froth baffles are placed between each unit mechanism to prevent migration of froth as the liquid flows along the tank. The liquor level is controlled at the end of each bank section by a combination of weir overflows and dart valves which can be automated. These units operate with a fully flooded impeller, and a low pressure air supply is required to deliver air into the eye of the impeller where it is mixed with the recirculating liquor at the tip of the air bell. Butterfly valves are used to adjust and control the quantity of air delivered into each unit.

Each cell is provided with an individually controlled air valve. Air pressure is between 108 and 124 kN/m2 (7 and 23 kN/m2 gauge) depending on the depth and size of the machine and the pulp density. Typical energy requirements for this machine range from 3.1 kW/m3 of cell volume for a 2.8 m3 unit to 1.2 kW/m3 for a 42 m3 unit.

In the froth flotation cell used for coal washing, illustrated in Figure 1.48, the suspension contains about 10 per cent of solids, together with the necessary reagents. The liquid flows along the cell bank and passes over a weir, and directly enters the unit via a feed pipe and feed hood. Liquor is discharged radially from the impeller, through the diffuser, and is directed along the cell base and recirculated through ports in the feed hood. The zone of maximum turbulence is confined to the base of the tank; a quiescent zone exists in the upper part of the cell. These units induce sufficient air to ensure effective flotation without the need for an external air blower.

Most of the industrial flotation machines used in the coal industry are mechanical, conventional cells. These machines consist of a series of agitated tanks (usually 48 cells) through which fine coal slurry is passed. The agitators are used to ensure that larger particles are kept in suspension and to disperse air that enters down through the rotating shaft assembly (Fig. 11.13). Air is either injected into the cell using a blower or drawn into the cell by the negative pressure created by the rotating impeller. For coal flotation, trough designs that permit open flow between cells along the bank are more common than cell-to-cell designs that are separated by individual weirs.

Some of the major manufacturers of flotation equipment include Wemco (FLSmidth), Metso, Svedala, and Outokumpu. The commercial units are very similar in basic design and function, although some slight variations exist in terms of cell geometry and impeller configuration. Machines with large specific surface areas are generally preferred for coal flotation, due to the fast flotation kinetics of coal and the large froth solids loadings. Flotation machines with individual cell volumes of up to 28m3 are commonly used due to advantages in terms of capital, operating and maintenance costs. Some manufacturers also offer tank machines, which consist of relatively short cylindrical tanks equipped with conventional impellers. The simplified structural design, which allows these machines to be much larger, can offer significant savings in terms of capital and power costs for some installations. Tank cells with volumes as large as 100m3 are already in operation at coal plants in Australia.

Unlike conventional, mechanically agitated flotation machines, which tend to use relatively shallow rectangular tanks, column cells used in the coal industry are usually tall vessels with heights typically ranging from 7 to 16m depending on the application. Unlike conventional flotation machines, columns do not use mechanical agitation and are typically characterized by an external sparging system, which injects air into the bottom of the column cell. The absence of intense agitation promotes higher degrees of selectivity and can aid in the recovery of coarse particles.

In general, feed slurry enters the column at one or more feed points located in the upper third of the column body and descends against a rising swarm of fine bubbles generated by the air sparging system (Fig. 11.14). Hydrophobic particles that collide with, and attach to, the bubbles rise to the top of the column, eventually reaching the interface between the pulp (collection zone) and the froth (cleaning zone). The location of this interface, which can be adjusted by the operator, is held constant by means of an automatic control loop that regulates a valve on the column tailings line. Varying the location of the interface will increase or decrease the height of the froth zone. The froth is transported from the froth zone into the product launder via mass action.

Methods of sparging in columns are numerous and include air lances, porous tubes, eductors, static mixers, and Cavitation-TubesTM. The air rate used in a column is selected according to the feed rate and concentrate-production requirements. This parameter typically has the largest effect on the operating point of the column with respect to the ash/yield curve. The bubbles generated by the air sparging system are sized to provide the maximum amount of bubble surface area given a constant energy input. In other words, the designs of the various sparging devices are engineered to provide the smallest size and largest number of bubbles possible.

For an equivalent volumetric capacity, the cross-sectional surface area of a column cell is much smaller than that of a conventional cell. This reduced area is beneficial for promoting froth stability and allowing deep froth beds to be formed. This is an important aspect of column flotation, as a deep froth bed facilitates froth washing for the removal of unwanted impurities from the float product. Wash water, added at the top of the column, percolates through the froth zone displacing dirty process water and non-selectively entrained particles trapped between the bubbles. In addition, froth wash water serves to stabilize and add mobility to the froth. Sufficient water must be added to ensure that all of the feed water that would otherwise normally report to the froth product is replaced with fresh or clarified water. It has been reported that less than 1% of the feed pulp and associated clays will report to the froth in a well-operated column (Luttrell et al., 1999). The ability to maintain and wash a deep froth layer is the main reason cited for the improved product grades when comparing column cells to conventional cells.

In contrast, conventional mechanical cells do not operate with deep froths. Therefore, these devices allow some portion of the ultrafine mineral slimes to be recovered with the water that reports to the froth. Consequently product quality is reduced by this non-selective hydraulic conveyance (i.e., entrainment) of gangue into the product launder. In fact, fine particles (<0.045mm) have a tendency to report to the froth concentrate in direct proportion to the amount of product water recovered. As such, the flotation operator is often forced to make the decision to either pull hard on the cells to maintain yield (e.g., wet froth), or run the cells less aggressively to maintain grade (e.g., dry froth).

The primary advantage of utilizing wash water is the ability to provide a superior product grade when compared to conventional flotation processes. This capability is illustrated by the test data summarized in Fig. 11.15, which compares column flotation technology with an existing bank of conventional cells. As shown, the separation data for the column cells utilizing wash water are far superior to those obtained from the conventional flotation bank. In fact, the data for the column cells tend to fall just below the separation curve predicted by release analysis (Dell et al., 1972). A release analysis is an indication of the ultimate flotation performance and is often regarded as wash-ability for flotation. This figure suggests that columns provide a level of performance that would be difficult to achieve even after multiple stages of cleaning by conventional machines.

There are a significant number of full-scale column installations currently in commercial service around the world. The most popular brands of columns include the CPT CoalPro (Eriez), Jameson, and Microcel columns. Although the Jameson cell does not have the traditional column geometry, it is included since it typically uses wash water to improve ash rejection. Details related to the specific design features of the various column technologies are available in the literature (McKay et al., 1988; Finch and Dobby, 1990; Yoon et al., 1992; Manlapig et al., 1993; Davis et al., 1995; Rubinstein, 1995; Wyslouzil, 1997). The primary difference between the various columns used in the coal industry is the type of air sparging system employed. These include porous bubblers, static mixers, and dynamic air injectors. Details related to the features and operation of these systems have been discussed extensively in the literature (Dobby and Finch, 1986a; Xu and Finch, 1989; Huls et al., 1991; Groppo and Parekh, 1992; Yoon et al., 1992; Finch, 1995). Ideally, the spargers should produce small, uniformly sized bubbles at a desired aeration rate. Other factors, such as equipment costs, mechanical reliability, wear resistance, and serviceability also need to be carefully considered prior to selecting an industrial sparging system.

Due to economy of scale, recent trends in the coal industry have shifted away from the installation of large numbers of smaller units toward fewer, large units with diameters up to 5m or more. Although most column installations involve the treatment of particles finer than 0.150mm, several recent column operations have been installed to treat coarser particles, such as minus 1mm feeds or deslimed 0.1500.045mm feeds. Additionally, a move to more economical cells in terms of energy efficiency has been realized as manufacturers focus on the generation of the required air bubble dispersions while using significantly less power than traditional approaches. One such device is the Eriez StackCell, which utilizes both pre-aeration methods in conjunction with traditional froth washing (Davis et al., 2011) to maximize efficiency with regard to both installation and operating cost.

The two most important requirements of laboratory flotation machines are reproducibility and performance similar to commercial operations. These two criteria are not always satisfied. The basic laboratory machines are scaled down replicas of commercial machines such as Denver, Wemco and Agitair. In the scale down, there are inevitable compromises between simplification of manufacture and attempts to simulate full scale performance. There are scaling errors, for example, in the number of impeller and stator blades and various geometric ratios. Reproducibility in semi-batch testing requires close control of impeller speed, air flow rate, pulp level and concentrate removal.

Until now, deaeration tanks always had to be placed underneath the flotation machine and also frequently in the cellar of a facility in order to ensure a sufficient height difference for the conveyance of foam. In addition, the tanks are open on top and can overflow with excess foam. That is now a thing of the past with the Deaeration Foam Pump (DFP) 4000. The new pump can be linked directly to the deinking machine and forms a clean and closed disposal system. Because it can be placed at the same level as the flotation cells, the entire flotation system saves more space than previous systems. A cellar or an additional floor height for the flotation is no longer required. The deaeration results are very impressive with the DFP 4000 from Voith Paper. The air content of the foam mass is reduced when passing through the pump from 80% to an average of 8%. Conventional deaeration systems offer approximately 12%. In addition, by using the DFP 4000, upstream foam destroyers, downstream long piping as well as pumps with high head pressures to overcome the floor height can be dispensed. With the DFP 4000, it is possible to deaerate and convey the foam, which is loaded with inks and other impurities, within a single machine. As a compact unit, it fully replaces the foam destroyer, foam tank stirring unit, and pump of previous deaeration systems. This means a clear reduction in investment costs for the tank, stirring unit, pipes, pumps, and floor space.

The DFP 4000, developed by Voith, is a compact unit that integrates several elements of the flotation deinking system. This combines the pump and deaeration machine into one unit. The deaeration foam pump replaces the foam destroyer, foam tank, stirring unit, and pump and costs less than the current suite of equipment. The DFP 4000 achieves better deaeration of the foam than conventional systems.

The DFP 4000 has two parts. In the upper part, foam is predeaerated by a mechanical foam destroyer. In the lower part, centrifugal force produced by a quick rotational movement further deaerates the foam. The resulting low-air-content suspension is brought to the required pressure so that it can be conveyed out of the machine to the next process stage. The air released during deaeration is conveyed out of the machine through a special air chamber on the side so that the airflow does not prevent the foam entering from above (Dreyer,2010).

The new pump can be linked directly to the deinking machine, forming a clean and closed disposal system. Because the deaeration pump can be placed at the same level as the flotation cells, the entire system requires less space than previous systems, so a cellar (or additional floor height) is no longer required to accommodate the system. When the foam mass passes through the DFP 4000, the foams air content is reduced from 80% to an average of 8% (Voith,2011a). Conventional deaeration systems reduce the air content to approximately 12%. The first DFP 4000 operating in a paper mill has been in service since September 2009 (Dreyer,2010). The benefits of the DFP 4000 are summarized in Table11.9 (Dreyer,2010; Voith,2011a).

Batch testing has been carried out using a specially designed 21 tumbler for mixing, and a standard Denver flotation machine for separation. A typical charge of the soil sample ranged from 200 to 600g, and the amount of coal varied depending on the contaminant concentration.

Figure 1 shows the block diagram of the 6T/day continuous unit. A slurry of contaminated soil and coal is fed at optimal solids concentration to a specially designed tumbler. In the front section of the tumbler, as a result of rotary motion, the solids are mixed and dispersed. In another section of the tumbler, layering, compaction and abrasion take place. After being discharged from the tumbler, the contents are screened into two streams. The 1mm particle size stream is directed to a high shear mixer where the oil-wetted coal particles are conditioned. The slurry is then transfered to flotation cells, where the coal microagglomerates, in the form of froth, are separated from clean soil. To facilitate dewatering and improve handleability of the combustible product, the froth can be subsequently fed into the low shear mixer for further agglomeration.

Flotation has progressed and developed over the years; recent trends to achieve better liberation by fine grinding have intensified the search for more advanced means of improving selectivity. This involves not only more selective flotation agents but also better flotation equipment. Since the froth product in conventional flotation machines contains entrained fine gangue, which is carried into the froth with feed water, the use of froth spraying was suggested in the late 1950s to eliminate this type of froth contamination. The flotation column patented in Canada in the early 1960s and marketed by the Column Flotation Company of Canada, Ltd., combines these ideas in the form of wash water supplied to the froth. The countercurrent wash water introduced at the top of a long column prevents the feed water and the slimes that it carries from entering an upper layer of the froth, thus enhancing selectivity.

The microbubble flotation column (Microcel) developed at Virginia Tech is based on the basic premise that the rate (k) at which fine particles collide with bubbles increases as the inverse cube of the bubble size (Db), i.e., k1/Db3. In the Microcel, small bubbles in the range of 100500m are generated by pumping a slurry through an in-line mixer while introducing air into the slurry at the front end of the mixer. The microbubbles generated as such are injected into the bottom of the column slightly above the section from which the slurry is with drawn for bubble generation. The microbubbles rise along the height of the column, pick up the coal particles along the way, and form a layer of froth at the top section of the column. Like most other columns, it utilizes wash water added to the froth phase to remove the entrained ash-forming minerals. Advantages of the Microcel are that the bubble generators are external to the column, allowing for easy maintenance, and that the bubble generators are nonplugging. An 8-ft diameter column uses four 4-in. in-line mixers to produce 56 tons of clean coal from a cyclone overflow containing 50% finer than 500 mesh.

Another interesting and quite different column was developed at Michigan Tech. It is referred to as a static tube flotation machine, and it incorporates a packed-bed column filled with a stack of corrugated plates. The packing elements arranged in blocks positioned at right angles to each other break bubbles into small sizes and obviate the need for a sparger. Wash water descends through the same flow passages as air (but countercurrently) and removes entrained particles from the froth product. It was shown in both the laboratory and the process demonstration unit that this device handles extremely well fine below 500-mesh material.

Another novel concept is the Air-Sparged Hydrocyclone developed at the University of Utah. In this device, the slurry fed tangentially through the cyclone header into the porous cylinder to develop a swirl flow pattern intersects with air sparged through the jacketed porous cylinder. The froth product is discharged through the overflow stream.

The process is carried out in a flotation cell or tank, of which there are two basic types, mechanical and pneumatic. Within each of these categories, there are two subtypes, those that operate as a single cell, and those that are operated as a series or bank of cells. A bank of cells (Fig. 8) is preferred because this makes the overall residence times more uniform (i.e., more like plug flow), rather than the highly diverse residence times that occur in a single (perfectly mixed) tank.

FIGURE 8. Flotation section of a 80,000t/d concentrating plant, showing the arrangement of the flotation cells into banks. A small part of the grinding section can be seen through the gap in the wall. [Courtesy Joy Manufacturing Co.]

The purpose of the flotation cell is to attach hydrophobic particles to air bubbles, so that they can float to the surface, form a froth, and can be removed. To do this, a flotation machine must maintain the particles in suspension, generate and disperse air bubbles, promote bubbleparticle collision, minimize bypass and dead spaces, minimize mechanical passage of particles to the froth, and have sufficient froth depth to allow nonhydrophobic (hydrophilic) particles to return to the suspension.

Pneumatic cells have no mechanical components in the cell. Agitation is generally by the inflow of air and/or slurry, and air bubbles are usually introduced by an injector. Until comparatively recently, their use was very restricted. However, the development of column flotation has seen a resurgence of this type of cell in a wider, but still restricted, range of applications. While the total volume of cell is still of the same order as that of a conventional mechanical cell, the floor space and energy requirements are substantially reduced. But the main advantage is that the cell provides superior countercurrent flow to that obtained in a traditional circuit (see Fig. 11), and so they are now often used as cleaning units.

Mechanical cells usually consist of long troughs with a series of mechanisms. Although the design details of the mechanisms vary from manufacturer to manufacturer, all consist of an impeller that rotates within baffles. Air is drawn or pumped down a central shaft and is dispersed by the impeller. Cells also vary in profile, degree of baffling, the extent of walling between mechanisms, and the discharge of froth from the top of the cell.

Selection of equipment is based on performance (represented by grade and recovery), capacity (metric tons per hour per cubic meter); costs (including capital, power, maintenance), and subjective factors.

jjf type flotation machine

Improvement: Shallow groove, the stator lower than the impeller, large slurry circulation volume, low energy consumption; the stator is a cylinder with an elliptical hole which is conducive to the dispersion and mixing of pulp and air. Umbrella shaped dispersion cover with hole keeps the pulp surface stable.

JJF flotation machine(floatation cell) is a new type of flotation equipment advanced in China. It can be widely used in the selection of non-ferrous metals, ferrous metals and non-metallic minerals. It is suitable for rough selection and sweeping of large and medium-sized flotation plants.

Large clearance between impeller and stator, the stator is a cylinder with elliptic hole, and it is good for mixing and dispersing the gas and pulp. The height of stator is lower than the impeller, pulp circulation volume is large, and it can be reached at 2.5 times of others.

When the impeller rotates, eddy current is generated in the vertical cylinder and the draft tube. The eddy current forms a negative pressure, and the air is sucked from the intake pipe and sucked in the impeller and stator regions and through the draft tube. Mix the pulp. The slurry gas mixing flow is moved by the impeller in a tangential direction, and then converted into a radial motion by the action of the stator, and uniformly distributed in the flotation tank. The mineralized bubbles rise to the foam layer, and the unilateral or bilateral scraping is the foam product.

continuous mechanical flotation cell | continuous mechanical flotation machine | continuous mechanical flotation separator - gtek

FX Model Continuous Mechanical Flotation Machine is applicable to separation of minerals with float-free method in labs. It is a unit of several combinations of two cells with number of the cell being even, varying from two to ten cells. Left or right type flotation machine can be supplied as required by customer.

FX flotation machine is a kind of impeller mechanical flotation machine which mainly consist of cell. It is made of welded steel plate and through impeller agitation and scraping device.1. To adjust the level of slurry in the cell and the thickness of the scraped froth layer, use wall plates of the two cells to make intermediary cell; install slurry level regulator; and mount orifice plate onto the cover in the cell to avoid negative effects on the froth zone exerted by the chaotic motion of slurry, as well as to avoid the gangue from being taken into the concentrate by the machine.Lining plates are installed at the cell so that the bottom of the cell will not be abraded. The lining plate can be replaced. On the outside of the cell bottom is a discharge mouth, which is used to discharge water during its cleaning.The slurry flows through the overflow mouth of wall panel into the intermediary cell and tail cell. It flows to the lower part of the intermediary cell and the duct covered by the lower part of the cell wall and then to the next cell. In this way, it can continue to flow through all the cells of flotation machine. It flows from the feed cell and is discharged from the discharge mouth of the tail cell. The front and back of the lower part of the cell is installed feeding mouth, to make it easy to change the process flow.2. The impeller system is a disk impeller which is installed in the center of the cell in the flotation machine and whose blades are radially arranged. It is fixed onto the lower end of the impeller shaft and revolves around the vertical shaft pipe. The upper end of the pipe lies above the pulp stone and the froth layer while its lower end is supported on the cover. When the impeller rotates, a large amount of air can be sucked along the vertical pipe. Below the cover is fixed protective disk. The gap between the safety disk and the impeller depends on the amount of sucked air. It can not be larger than 3mm at most. When the gap is too large, replace the abraded protective disc and make appropriate adjustment.The holes in the vertical pipe are used to circulate slurry as well as mix the slurry and air. The rolling shaft installed inside the bearing shell above the impeller shaft rotates. The bearing shell is installed on the crossbeam and belt pulley is fixed on the top of the shaft which rotates through the V-belt when the motor is turned on. The tension of the V-belt is adjusted through the nuts.3. Scraping device: The froth is scraped along the flotation machine through rotary scraper. The scraper is installed outside the discharge mouth of cell. At one end of the scraping shaft is installed belt pulley which rotates through the drive of worm reducer and V-belt.

flotation machines | mineral processing machine & solutions - jxsc

Flotation is the most widely used beneficiation method for fine materials, and almost all ores can be separated by flotation. Another important application is to reduce ash in fine coal and to remove fine pyrite from coal. The flotation machine is mechanical equipment for realizing the froth flotation process and separating target minerals from ore. At present nearly 2 billion tons of ore in the world are treated by the froth flotation process. According to rough statistics, about 90% of non-ferrous minerals are recovered by the flotation method, accounting for 50% proportion in the field of ferrous metal mineral separation.

Suitable material Sulfide minerals, oxide minerals, non-metallic minerals, silicate minerals, nonmetallic salt minerals, soluble salt minerals, rare earth minerals, etc., including gold, silver, copper, lead, zinc, galena, zinc blende, chalcopyrite, pyroxene, molybdenite, nickel pyrite, malachite, cerussite, smithsonite, hematite, cassiterite, wolframite, Ilmenite, beryl, spodumene, brimstone, graphite, diamond, quartz, mica, feldspar, fluorite, apatite, barite, and so on.

The flotation machine is composed of single or multiple flotation cells, by agitating and inflating the chemical reagent treated slurry, some mineral ore particles are adhered to the foam and float up, and then be scraped out, while the rest remains in the slurry.

Industrial flotation machines can be divided into 5 classes, mechanical agitation flotation machine, pneumatic flotation machines, flotation column, airlift flotation machine, froth separation flotation machines. At present, the mechanical flotation machine is the most commonly used in industry, followed by the column flotation which has recently set off hot spot, the pneumatic type and froth separation are not common.

Commonly used flotation models TankCell series, Wemco series, Agitair series, SuperCells, RCS(reactor cell system), Denver laboratory flotation, KYF, and XCF series flotation devices, laboratory flotation machine. Well-known flotation machine manufacturers have Outotec, Flsmidth, Metso, BGRIMM, JXSC flotation machine china; column flotation manufacturers or models have Jameson, CPT, Counter-flow inflatable flotation column.

Main parts: slurry tank, agitator device, mineralized froth discharging system, electromotor, etc. 1. Slurry tank: mainly consist of a slurry inlet, slurry tank and a gate device for controlling the slurry volume, welded with steel plate. 2. Agitator: slurry tank have a series of the mechanically driven impeller that disperses the air into the agitated pulp. 3. Mineralized forth discharging: the useful minerals are enriched in the foam, scraped out, dehydrated, and dried into concentrate products.

Whatever flotation machines design is selected, it must accomplish a series of complicated industrial requirements. 1. Good mixing function. a qualified flotation machine should mix the slurry uniformly and maintain the particles especially the target mineral particle in suspension with the pulp, maximum the froth-mineral probability. 2. Adequate ventilation and distribution of fine bubbles. Except for the flotation machine performance, the frother type and dosage also matter to the distribution of the bubbles. 3. Appropriate agitation control in the froth beds. It is should pay importance to keep froth zones smoothly, which ensures the suspension of collector coated particle.

1. The throughput capabilities of various cell designs will vary with the ore property (beneficiability, size, density, grade, pulp, PH, etc.). In the case of ore easy separated, and a small amount of air inflation required, may choose a mechanical flotation machine; if the minerals with coarse size, proper to choose the KYF, BS-F, ore CLF type; what's more, when in case of ore easy separated, fine particles, high grade, low PH, flotation column is the best, especially in the concentrating process. 2. There is a difference between the process of concentrating, rough selecting. Thin froth layer is better for separate mineral particles, thus may not choose a large air inflation flotation machine.

Mining Equipment Manufacturers, Our Main Products: Gold Trommel, Gold Wash Plant, Dense Media Separation System, CIP, CIL, Ball Mill, Trommel Scrubber, Shaker Table, Jig Concentrator, Spiral Separator, Slurry Pump, Trommel Screen.

types of flotation machines - jxsc machine

Flotation machine is the abbreviation of floating concentrator, refers to the completion of flotation process equipment. In the flotation machine, the ore particles and the flotation agent are mixed and stirred to form a slurry, wherein some of the ore particles are selectively fixed on the bubbles, and then float up to the slurry surface, and the remaining ore particles are retained in the slurry to achieve froth flotation mineral separation. There are many types of flotation machines. The most commonly used ones are mechanical agitating flotation machines, aerated agitating flotation machines and inflatable flotation machines (flotation columns).

The aeration and agitation of the slurry are completed by the impeller and mechanical agitation device of the flotation machine. It belongs to the external gas self-priming flotation machine, generally the upper gas suction type, that is, air inhaled near the mechanical stirring device in the lower part of the flotation tank.

This kind of flotation machine can not only self-prime air, but also self-priming slurry. It is easy to realize self-flow when returning the ore middlings, less auxiliary equipment, neat equipment configuration, simple operation and maintenance, etc. But this type of machine has small inflation and high power consumption.

As the impeller rotates, the slurry in the tank is sucked from the bottom of the tank from the lower end of the impeller to the impeller vane. At the same time, the low-pressure air fed by the blower enters the air distributor through the hollow shaft and the impeller. After the slurry and air are thoroughly mixed between the impellers, they are pushed out obliquely from the periphery of the upper half of the impeller, and the stator is stabilized and oriented to enter the entire trough. The bubble rises to the foam stabilization zone. After the enrichment process, the foam overflows from the overflow weir and enters the foam tank. A part of the slurry flows to the lower part of the impeller, and then is stirred by the impeller to remix to form mineralized bubbles, and the remaining slurry flows. The next trough until it eventually becomes tailings.

Advantages 1. Strong stirring force can ensure the suspension of mineral particles with large density and large particle size, and can promote the dispersion and emulsification of insoluble chemicals. 2. For the complex process of sorting polymetallic ore, self-priming can rely on the suction of the impeller to achieve the return of the mine, eliminating the need for a large sand pump. 3. When it is difficult to select and complex ore or hope to obtain high-grade concentrate, it can guarantee a better stability index. 4. The moving parts have high speed, high energy consumption, serious wear and large maintenance. Disadvantages 1. A large amount of inflation is easy to adjust, which is beneficial to increase production and adjust the process. 2, the stirring does not work, so the speed is low, the wear is small, the energy consumption is low, and the maintenance is small. 3. The liquid level is stable, the mineral mud is less, and the sorting index is good, but the gas pressure system and pipeline are needed.

The agitation device of the aerated agitation flotation machine only functions to agitate the slurry and distribute the airflow. The air is mainly pressed into the slurry by an external fan, and the aeration and the agitation are separated.

The air is supplied by the external blower, and the amount of inflation can be adjusted by the valve according to the needs of the flotation. Since the impeller only acts as a stirring force, the rotation speed is low, the stirring is not strong, and the flotation of brittle minerals is not easy to produce mud. The slurry surface is relatively stable, and it is easy to form a stable foam layer, which is conducive to improving the selection index. The impeller rotates at a low speed, the slurry flows by gravity, the unit consumes less electricity, and the service life is longer, and the equipment maintenance cost is also low.

When the impeller rotates, the slurry in the tank is sucked into the impeller blade from the bottom of the tank through the bottom of the tank from the lower end of the impeller. At the same time, the low-pressure air fed by the blower enters the impeller chamber through the air duct, the air regulating valve and the hollow main shaft, and the slurry and air are in the impeller blade. After being thoroughly mixed, it is discharged from the periphery of the upper half of the impeller, and the discharged ore flow moves obliquely upward. After being stabilized and oriented by the stator installed obliquely above the impeller, it enters the entire trough.

The mineralized bubbles rise to the surface of the trough to form a foam. The foam flows into the foam tank, the slurry is returned to the impeller area for recycling, and the other part is re-selected through the flow holes in the inter-groove wall.

The gas required for flotation of the aerated mechanical agitation flotation machine is mainly forcibly fed by an external force (blower), which is characterized by a large adjustment range of the inflation amount and accurate adjustable size, which is particularly suitable for a large amount of inflation. The flotation of minerals, and with the large-scale flotation machine, consumes less total power than self-inhalation, making it easy to optimize the design and optimize operation.

Advantages (1) DC tank design, the pulp passing capacity is large, and the flotation speed is fast; (2) The centrifugal blower (pressure is 0.245kg/cm2) is used for gas supply, and the amount is adjusted within a certain range according to the process requirements; (3) Small footprint, lightweight per unit volume; (4) The ore particles are suspended in the tank, which reduces the deposition and stratification of coarse particles in the tank, and can increase the upper limit of the floatable particle level; (5) The impeller is only used to recycle the slurry and the dispersed air. The impeller of the deep tank flotation machine can still work at low speed, so the spare parts wear and energy consumption is low, the energy consumption is low, and the mineral liquid surface is relatively stable. Conducive to the enlargement of equipment and increase production capacity; (6) The axial and radial clearance between the impeller and the cover are larger than the A-type flotation machine, and it is easy to install and adjust; (7) The drug and energy consumption were significantly reduced, and the selection index was improved.

Disadvantages The disadvantage of this type of flotation machine is that the foam (middle mine) cannot be returned, and a foam pump (which can also be provided by a suction tank) is required. And the configuration can not be in the same plane, requiring a stepped configuration. This machine is suitable for rough and scavenging operations of large and medium-sized flotation plants.

The flotation column has the advantages of simple structure and easy manufacture. The disadvantage is that there is no agitator, and the flotation effect will be affected to some extent. The aerator is easy to form calcium, which is not conducive to air dispersion. With the re-emergence and successful application of foreign flotation column technology, China has developed several flotation columns for industrial production. The flotation column is suitable for the rough selection and scavenging operations of the easy-to-select ore which is composed of simpler and higher grades.

Inflatable flotation machines use a vertical circulation of slurry and sufficient low pressure air to increase the efficiency of the selection. The vertical circulation of the slurry in the flotation tank produces an upflow, which eliminates the occurrence of stratification and grit in the flotation machine, increases the possibility of sorting coarse and heavy minerals, and help the ore and bubbles to collide.

When the impeller rotates, the slurry in the impeller chamber is mixed with the air and then thrown out, so that the back surface of the impeller blade becomes a negative pressure zone, and the circulating slurry enters the negative pressure zone through the annular hole between the circular cylinder and the bell.

The low-pressure air enters the impeller chamber sealed by the circulating slurry, which promotes the thorough mixing of the air and the slurry in the impeller chamber. The mixture is smashed on the cover blade by the centrifugal force generated by the rotating impeller and further disperses and disperses the air bubble. In the slurry, under the action of the vertical circulating upflow, the bottom of the entire trough is diffused upward, so that the foam is separated from the gangue mineral in the calm zone above the trough, and the useful mineral is selected into the foam product.

The inflating action of the flotation machine is not to draw air into the tank by the negative pressure zone generated by the rotating impeller, but to supply air to the impeller chamber through the central cylinder by a blower. The aeration efficiency is mainly related to the amount of aeration and the amount of pulp circulating through the impeller. The amount of inflation can be adjusted as needed, and the maximum inflation can reach 1.5~1.8 m3/(m2min).

Because this flotation machine does not need to generate negative pressure suction, its impeller speed is low. Therefore, the motor power can be small, the power consumption is reduced, and mechanical wear is reduced. Many large flotation machines developed at home and abroad are inflated mechanical mixing types.

Advantages 1. Simple structure, convenient manufacturing and maintenance, low investment and low operating cost; 2. Create suitable dynamic collision of bubbles and particles and static separation of bubbles and particles, which is conducive to fine-grain classification; 3. can introduce other force fields, strengthen sorting, foam thickness, bubble size and quantity adjustment; 4. the flotation speed is fast, the process is simplified (one operation is equivalent to the flotation machine several operations); 5. Large enrichment ratio, high recovery rate and large processing capacity, especially suitable for processing fine particle size and easy to control and enlarge.

Disadvantages The disadvantage of the flotation column is that the particles are difficult to suspend, and the probability of contact between the bubbles and the particles is small. In order to improve the recovery rate of the grade loss, it is generally used for rough selection and sweeping operations, and the self-flow configuration is complicated. The bubble generator has an external and built-in method, and the bubble generator is easily fouled and inconvenient to replace in the high alkalinity slurry.

JXSC mine machinery Company in China has more than 30 years of professional experience at the mining equipment manufacturing, mineral processing plant design. We provide a complete set ore processing machines, custom process flowchart, besides, send the engineer to the mine site for equipment installation and commissioning guidance. Hot Products: rock crusher, gravity separator, magnetic separator, flotation machine, etc.

mechanical flotation machine

SUBSTANCE: the invention concerns to the devices for a flotation of materials and may be used in mining, metallurgical, food and other industries. The technical result is decreased power input at maintaining a high quality of dispersion, and increased productivity of the machine. The flotation machine contains a chamber and an aeration unit consisting of a stator and an impeller mounted in respect to each other with an axial and a radial clearance. In the upper part of the impeller on blades there is a ring-type element, the width of which is more than 1/2 lengths of a blade of an impeller. The internal diameter of the ring is equal to the diameter, which forms an internal butt surface of a blade of the impeller, and above the ring-type element there is the circulation pipe.

Closest to the technical essence and the achieved result is a mechanical flotation machine, comprising a chamber, an aeration unit, which consists of stator and impeller mounted relative to each other with a gap (Meshcheryakov NF "Flotation machines", M.: Nedra, 1972, p.41-46).

A disadvantage of the known flotation machine is the large energy consumption, due to the fact that flotation machine works, like "open the pump, the faster rotation of the impeller, the greater the vacuum and sucked more of the pulp. Thus, during operation of the flotation machine and to increase its performance, it is necessary to increase the pumping of the pulp, through the more rapid rotation of the impeller, spending a large amount of energy.

This technical result is achieved in that in a mechanical flotation machine, including the camera and the aeration unit, which consists of them is of eller and stator, installed relative to each other with axial and radial clearances, according to the invention, in the upper part of the impeller blades has an annular element whose width is more than 1/2 the length of the blades of the impeller, the inner diameter of the ring is equal to the diameter forming the inner end surface of the vanes of the impeller, and over the annular element with a clearance of not less than 5 mm posted by circulating pipe.

The establishment in the upper part of the impeller, the blades, the annular element whose width is more than 1/2 the length of the blades of the impeller provides the most complete overlap of the blades of the impeller, which eliminates the flow of the pulp, thereby at the same speed of rotation of the impeller in the proposed flotation machine compared to the prototype provides greater depression, and in turn greater pumping slurry, which reduces energy costs while maintaining productivity and quality of dispersion.

The establishment of the circulation pipes above the annular element with a clearance of not less than 5 mm provides directional circulation of the pulp on the impeller, and because the ku intensity of the vortex depends on the size of the stream, which directly adjoin the rotating blades of the impeller are provided with higher aeration characteristics of the flotation machine and increases its performance.

The size of the gap h between the ring element and the circulation pipe not less than 5 mm is selected based on the fact that during the rotation of the impeller in the space between the impeller and the stator is drawn in the pulp, which is then dumped into the blades of the stator, in addition, adjacent to the surface of the impeller layers of pulp are involved in the annular gap between the impeller and the stator. If the size of the gap h is less than 5 mm, there is a large hydrodynamic resistance in the annular gap between the pipe and the annular element flows slurry, pumped by the impeller. Pulp cannot easily penetrate between the blades of the stator, forming a torus flow in the space between the impeller and the stator, which may lead to the termination of receipt of the pulp chamber. While the energy consumption increases and worsens the dispersion of air at the edges of the blades of the stator (formed too large air bubbles).

Flotation machine includes a camera 1, in which aeration is the node containing the stator 2 and the impeller 3, associated with the shaft of the m 4 and the actuator (not shown). In the upper part of the impeller 3 on his blades 5 has a ring element 6, above the annular element 6 posted by circulating pipe 7, and the gap (h) between the bottom base of the tube 7 and the annular element 6 is not less than 5 mm Width (a) of the ring element 6 is more than 1/2 length (in) blades 5 of the impeller 3. Inside the circulation pipe 7 to the axis of the shaft 4 is posted casing pipe 9.

The slurry is sucked through the pipe 8 through the circulation pipe 7 into the cavity of the impeller and thrown through bezlopastny space of the impeller 3 in volume of the chamber 1. The circulation pipe 7 provides a directed flow of the pulp on the impeller 3, which in turn allows us to provide the highest aeration characteristics of the machine and increase its performance.

At the same time through the casing 9 in the impeller sucked air, which is intensively dispersed due to disruption from the end of the blades 5 of the impeller 3 in the zone of maximum velocity. The flow of the pulp passing through the impeller 3, further disperses the air in a turbulent vortices formed due to differential velocity at the outlet of the aerator.

Around the impeller 3 in the annular gap formed by the rotation of the stream flow over the surface of the impeller adjacent to the surface of the impeller layers of pulp engage the annular gap between the impeller and the stator. If the gap between the ring element 6 and the circulation pipe 7 is less than 5 mm, there is a large hydraulic resistance to the flow of the slurry, pumped by the impeller. Formed tore flow, which may lead to the termination of the receipt of the pulp from the chamber.

The setting at the top of the impeller 3 to the blades 5 of the ring element 6, the width (a) greater than 1/2 length (in) blades 5 of the impeller 3, provides the most complete overlap of the blades of the impeller, which eliminates the flow of the pulp, which in turn reduces energy consumption while maintaining the performance and quality of dispersion.

The choice of the size of the gap between the ring element 6 and the circulation pipe 7 is not less than 5 mm allows you to increase the pumping slurry through this gap, which reduces energy consumption and increases the efficiency of the flotation machine.

Mechanical flotation machine, including the camera and aeration node, comprising the C impeller and the stator, installed relative to each other with axial and radial clearances, characterized in that the upper part of the impeller blades has an annular element whose width is more than 1/2 the length of the blades of the impeller, the inner diameter of the ring is equal to the diameter forming the inner end surface of the vanes of the impeller, and over the annular element with a clearance of not less than 5 mm posted by circulating pipe.

Mechanical flotation machine, including the camera and aeration node, comprising the C impeller and the stator, installed relative to each other with axial and radial clearances, characterized in that the upper part of the impeller blades has an annular element whose width is more than 1/2 the length of the blades of the impeller, the inner diameter of the ring is equal to the diameter forming the inner end surface of the vanes of the impeller, and over the annular element with a clearance of not less than 5 mm posted by circulating pipe.

SUBSTANCE: the invention concerns to the devices for a flotation of materials and may be used in mining, metallurgical, food and other industries. The technical result is decreased power input at maintaining a high quality of dispersion, and increased productivity of the machine. The flotation machine contains a chamber and an aeration unit consisting of a stator and an impeller mounted in respect to each other with an axial and a radial clearance. In the upper part of the impeller on blades there is a ring-type element, the width of which is more than 1/2 lengths of a blade of an impeller. The internal diameter of the ring is equal to the diameter, which forms an internal butt surface of a blade of the impeller, and above the ring-type element there is the circulation pipe.

FIELD: water treatment systems; devices for circulating treatment of water by floatation; purification of drinking water at home and in food-processing industry; purification of industrial water containing surfactants.

SUBSTANCE: proposed plant includes reservoir, aerator and vertical extractor equipped with bell-mouth from below for entrapping air bubbles and foam receiver at the top, as well as with pump fitted with suction and discharge branch pipes, pump drive and column mounted in reservoir above extractor; aerator is made in form of water-and-air ejector with nozzle-type inlet branch pipe communicated with discharge branch pipe of pump, air intake branch pipe communicated with atmosphere and outlet branch pipe communicated with column. Suction branch pipe of pump is communicated with reservoir.

SUBSTANCE: the invention is pertaining to the field of mining, in particular, to production of devices used for materials flotation, that may find application in metallurgical, food and other industries. The aeration assembly contains an aeration pipe for air supply and a mounted on it cone-shaped impeller with its smaller base downwards and a cylinder connected with a smaller cone base. The impeller in addition contains the second stage, that represents a concentric ring with the mounted on it radial vanes interposed in the radial slits of the lower stage upper base made in the form of a dead disk. In the lower third of the cone within the intervane intervals and in the connected with it cylinder there are vertical grooves forming a "corona". The lower stage radial vanes, the aforesaid lateral surface of which represents a truncated conical surface, are mounted perpendicularly to the cone surface. The technical result is improved quality of aeration of the fine pulp, decreased power consumption used for aeration, stabilization of the flotation process.

SUBSTANCE: flotation apparatus has case made rectangular in plan and provided with paired partition walls. Perforated pipelines for supplying of air-and-water mixture, froth removal mechanism with froth collector, and unit adapted for discharging of waste water and equipped with receptacle pocket are mounted between partition walls. Stepped baffles are disposed on partition walls above perforated pipelines. Stepped baffles are made wedge-shaped or truncated wedge-shaped. Bases of wedges or truncated wedges are aligned with surfaces of partition walls. Lower faces of wedges are perpendicular to axes of openings of perforated pipelines so that stream strikes against lower step of baffle.

SUBSTANCE: the invention is pertaining to the installation for industrial waste waters treatment and is intended for treatment of the waste waters contaminated by wastes of petroleum, products of its processing, fats, oils, products of organic synthesis, surface-active substances, fine light suspended substances, activated sludge, etc. The installation for floatation water treatment contains: the main flotation chamber; a centrifugal pump; a catalyst chamber of a flocculation in series connected with the main flotation chamber by means of the perforated pipes, which have been made with a capability to feed the subjected to treatment water into the bubbling bed of the chamber; a hydraulic elevator linked by the pressure pipeline with the centrifugal pump and the pipe duct of waste water. The flotation chamber is supplied with the microporous diffuser pipes for the air passing through them, and is in series connected with the chamber of the treated water collecting. The centrifugal pump is connected to the chamber of the treated water. The technical result is improvement of the quality of a waste water treatment.

SUBSTANCE: electric flotator comprises flotation chamber with vertical walls, inclined ceiling, system for dispersing gas, and foam collector, second flotation chamber. The gas dispersing system is made of the electrode units made of graphite anode that covers the bottom of each flotation chamber and cathode made of stainless grid having the 0.4-mm wire diameter and mounted at a distance of 8-10 mm from the anode.

SUBSTANCE: invention relates to chemical mechanical engineering field and is intended to local treatment of strongly polluted waste waters containing petroleum derivatives, fats, suspended substances, metal hydroxides, synthetic surfactants, organic, and other types of contaminants. Flotation treatment installation comprises, within a closed hydraulic system, (i) hydraulic recirculating unit composed of pump assembly with suction and pressure lines, water-an-air ejector, and upright saturator, and (ii) flotation treatment unit. Saturator is provided with water-air mixture supply pipeline coming out of top part of saturator and connected through nozzle to two-zone device attached from outside to body of flotation treatment unit. From bottom part of saturator, pressure stream distributor with two diverting pipes is led out, said diverting pipes being connected to liquid ejector of second chamber of flotation unit and to ejector of hydraulic recirculating unit. Two-zone device is waste water receiver in the form of wire basket communicating with first chamber of flotation through holes. Flotation treatment unit is structurally made in the form of cylindrical body transforming into truncated cone in its lower portion. Inside the body, flat-bottom cylindrical container with segment-shaped slot in its bottom is axially disposed to form second flotation chamber. First flotation chamber is represented by space between inside surface of body of the flotation treatment unit and outside surface of the second flotation chamber. In bottom portion of the second flotation chamber, there is a tubular distributive collector disposed and overflow pipe with head wall and scraper sludge remover are disposed axially in the same chamber. Between overflow pipe and inside cylindrical surface of the second flotation chamber, there is cylindrical barrier disposed to separate second flotation chamber space into two zones. Spaces of the first and second flotation chambers are traversed by sludge chute.

SUBSTANCE: method involves stage of static flocculation with descending flow, said stage comprising the step of primary separation of heavier particles, with zone where primary separation of heavier particles is performed being positioned under zone, wherein static flocculation step is performed, and including removal of heavier particles, with settling velocities of heavier particles held at this stage of static flocculation/primary separation being lower or equal to settling velocities of floated particles, and flotation step, during which step light particles are removed, with settling velocity of light particles being lower than cutoff threshold of settler. It is preferable that before flocculation step, high-energy mixing step be provided, said step being combined with introduction of one or number of reactants, such as coagulant or flocculant. Apparatus for effectuating said method according to any version comprises static flocculator equipped with deflectors and cutoff devices, lamellar settler positioned directly under static flocculator, and flotation unit with high pressure-expansion system designed for generation of bubbles for flotation of lighter particles, said parts of apparatus being arranged in one and the same volume. Apparatus is further provided with one or number of mechanical flocculation cells, which are supported during mixing process and into which flocculant is injected. Cell is positioned between coagulator and static flocculator-lamellar settler.

EFFECT: provision for optimal quality of clarification with the use of flotation treatment of water containing floatable and non-floatable particles, compact construction and provision for preventing formation of bottom sediment in flotation unit.

SUBSTANCE: the invention is pertaining to the field of food-processing industry for purification of the liquid mediums from the suspended particles, greases and other impurities. The device includes the inlet of the subjected to purification liquid(1), the inlet of the gas (2), the flotator (5) with the chute for the froth removal (6), the hazemeter (10) and the withdrawal of the purified liquid, the set of the bubblers (7), the compression pump (4), the deaerator (8), the gas flow regulator (14) and the control unit (11), which by the signal of the hazemeter selects the corresponding bubbler, at operation of which the turbidity of the purified liquid is minimal. The outlet of the gas flow rate sensor (13) is connected to the regulator inlet, and the outlet of the compression pump is connected through the unit of control valves (12) to the unit of the bubblers. The invention ensures the increased efficiency of the liquid mediums purification by flotation and the functional reliability of the device.

SUBSTANCE: the invention is pertaining to the mining industry, in particular, to the devices for floatation of the substances and may be used in metallurgy industry, the food-processing industry, in other branches at purification of the industrial waste waters. The assemblage for the foam removal is made in the form of the blade, which have been fitted on the arbor. In the fixed on the arbor supports the blade is bent in the form of the logarithmic spiral having the constant angle of attack {the striking angle) onto the foam layer, and the supports are mounted on the arbor with the capability to adjust the foam skimming in height. The technical result of the invention ensures the increased productivity of the floatation machine, reduction of the power inputs on aeration and stabilization of the flotation process.

bgrimm pneumatic mechanical agitation flotation machine | springerlink

With the changes in mineral resource endowments, especially the increasing proportion of low-grade ores, large pneumatic flotation machines have been developed rapidly and become the most widely applied flotation machines. There are many kinds of non-ferrous, ferrous and non-metallic minerals in China, but the resource grades are not high, and the separation is very difficult.