Ganzhou Gelin Mining Machinery Co., Ltd. is an over 30 years experience expert manufacturing mining machines in China, covering an area of over 30,000 square meters, having more than 25 sets of heavy processing equipments and with an annual output of more than 2000 sets of mining machinery.We have international level & experienced engineer team and a strong R&D department and have been cooperating with domestic and oversea Scientific Research Institutes for many years. Our purpose is to track i...
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Prater offers a wide range of equipment for particle size reduction, feeding and separation such as lump breakers, hammer mills, fine grinders, air classifying mills, rotary sifters, air classifiers, rotary airlock valve feeders, and more. All Prater equipment, parts and systems are designed and built to provide years of low-maintenance, reliable service. Prater also offers highly skilled and experienced technical services on-site for start-up, troubleshooting, and preventative maintenance.
A vibrating screen is a necessary machine for mining and quarrying industries. In the quarrying field, the screening process always follows the primary and secondary crushing stages to divide rock material into more than three sizes from coarse to fine.
Actually, how many sizes of material do you want to get depends on how many screen decks you adding to the machine, which greatly improves the value of raw material. Besides, the vibrating screen also plays a key role in the ore mining industry where ore beneficiation process has strict requirements on the size of ore. For example, before entering a ball grinding mill, ores must get their size meet a ball mill opening size, and be not containing impurities with the help of a vibrating screen.
The working principle of a vibratory screen is quite simple, which makes it easy to operate. The crucial parts of the machine include vibrating screens, exciter, motor, screen decks, liners, and side plates.
Vibrating source comes from an exciter that transmits vibration to the screen deck by the V-belt, which makes material shaking and distributing evenly on the screen. During the process, the large size of material will stay on the top while the small and fine size material can go throughout the screen mesh to the bottom, then youll get different sizes of materials.
The vibration of screen is generated by an exciter which consists of housing, bearing, shaft and an eccentric mass. In-deep speaking, the motor passing the driving force to exciter by V-belt, and then eccentric mass rotating around the exciter shaft to create vibration.
The screening and frequency can be adjusted by changing the ratio of the V-belt sheaves. The high-quality exciter can performance a force output of 1000 KN, keeping excellent operational performance and economic efficiency.
The task of the balance wheel is to ensure centrifugal forces evenly distributing around the axis of rotation, otherwise, the unbalanced cause the pulley to vibrate thus leading to premature or even catastrophic failure.
An inclined vibrating screen is one of the most popular screening machines. The inclination of this type of screen is at the range of 15 to 30 degrees. Screening stroke can be adjusted by remove or add eccentric mass and is generally at 8mm to 12mm.
The inclined screen utilizes gravity to help material move downward. Besides, the circular motion also helps to separate coarse and fine material. This type of vibrating screen is often applied in stone crushing, sand making, ore processing, construction waste recycling, wet screening, and chemical fields.
The inclination angle of the horizontal vibrating screen is between 0 degrees and 5 degrees, almost parallel to the ground. It is equipped with a triple drive mechanism that combines advantages of linear and circular vibration types in elliptic vibration.
The triple drive mechanism can keep material moving horizontally under the help of linear vibration while avoid them plunging because of the circular vibration. A horizontal screen has a simple structure, reliable performance, and large capacity, and can overcome any condition. So, it is the most practical vibrating screen in the quarrying field.
The outstanding feature of a high-frequency screen is high frequency and low amplitude, which ensures a faster material speed thus greatly improving screening efficiency. It is perfect for screening feeds containing solid and crushed ores down to approximately 200m in size.
It is mostly used in dehydration wet screening in which a filtering layer on the screen surface can block the passage of fine material thus reducing the loss of solid materials in water and improving the recovery rate of solid. It is applied for screening and separating iron ore, tin ore, tungsten, tantalum, and niobium, etc.
Fote is one of the leading manufacturers of high-quality vibrating screens. It mainly produces circular motion vibrating screens/inclined vibrating screens, horizontal vibrating screens, high-frequency vibrating screens, drum screens. If you have any needs, please consult our experienced screen engineers to obtain solutions and other information and suggestions.
As a leading mining machinery manufacturer and exporter in China, we are always here to provide you with high quality products and better services. Welcome to contact us through one of the following ways or visit our company and factories.
Based on the high quality and complete after-sales service, our products have been exported to more than 120 countries and regions. Fote Machinery has been the choice of more than 200,000 customers.
No two process applications are the same, and Coperion K-Tron offers the widest range of feeding solutions in the industry. From screw feeders to vibratory feeders, bulk solids pumps, weigh belts, liquid feeders and flow meters, all feeders are offered in a variety of configurations, which can be combined to create an optimal solution for any application.
We offer highly accurate solutions for handling a wide range of ingredients. Paper or plastic? Food or pharmaceuticals? Whatever the industry, we supply the feeders at the core of your manufacturing process. Our feeders can be found wherever bulk materials are processed, for a wide variety of applications. From chocolate chips to fiberglass, floodable powders to plastic pellets and waxy liquids, Coperion K-Tron offers the right feeder for any material.
Most feeders are available in either standard finish or special finishes with higher polish levels and ground welds for applications in the food industry, for example. A special line ofscrew and vibratory feeders has been developed specifically for the strict hygiene requirements of applications in the pharmaceutical industry.
Coperion K-Trons unique vibrating wire weighing technology is based on the theory that the resonance frequency of an oscillating wire depends on the wire tension produced when a load is applied. Force, when derived from an applied weight, is transferred mechanically to the wire. The resonant frequency is measured to determine the weight. In Coperion K-Trons patented Smart Force Transducer (SFT), the signal is directly converted into a digital weight signal by a built-in microprocessor. The signal is then communicated noise-free via RS 485 to the controller. Every SFT provides a true 4,000,000:1 weight resolution in 80 ms and comes with a 5 year warranty.
No matter how simple or complex your feeder application may be, Coperion K-Tron has a control solution designed and priced to meet your needs.Coperion K-Trons SmartConnexTM concept represents a new control environment that tightly integrates the core technologies of a feeder system. This greatly reduces the cost of installation and daily operation, makes the system easier to use and maintain, and provides an optimum level of performance. In multi-feeder applications, SmartConnex can be used to form a network of feeders using simple field wiring techniques with superior performance.
No two process applications are the same, and Coperion K-Tron offers the widest range of material handling solutions in the industry. All volumetric feeders, loss-in-weight feeders, weigh belts, flow meters and conveying systems are offered in a variety of configurations, which can be combined to create an optimal solution for any application.
Process equipment manufacturers have developed a vast body of expertise and a wide range of feeding technology options to address the multitude of challenges that can arise for process operations involving bulk solids. Your feeder selection, and the success of your application, will be greatly influenced by the specific characteristics of the materials you must feed, the recipe precision needed for your process and the throughput required.
The flow behavior of different bulk solids can vary greatly depending on the material properties or particle geometry. No one feeder design or feeder size can handle all the different material characteristics or throughput requirements. The following short list describes the behaviors most commonly encountered and the feeding solutions that feeder equipment manufacturers such as Coperion K-Tron have developed to handle these bulk solids challenges.
Easy-flowing materials, such as plastic pellets, granules and flakes, are most frequently metered with a single screw feeder. A variety of screw sizes and geometries are available to accommodate different material characteristics and desired feedrates. Bulk Solids Pump (BSP) feeders and vibratory feeders also provide gentle, precise feeding of free-flowing materials. BSP feeders employ a patented positive displacement action that feeds free flowing material with exceptional accuracy.
Floodable materials, including fine materials such as fumed silica, gypsum and diatomaceous earth, can behave like liquids if not properly controlled during hopper discharge and feeding. Here a feeder with interlocking twin screws is often the best choice. The intermeshing screw flights act as a valve to control material flow.
Difficult-flowing materials, such as fiberglass and rubber particles, often require special feeder designs and other flow-aid devices to enable better control of discharge during feeding. There are many different metering options, with screw feeders and vibratory feeders being the most frequent choices.
Cohesive materials, such as titanium dioxide, pigments, APIs and copper concentrates, create additional challenges during process operations, and are particularly susceptible to bridging inside hoppers and cake or accrete to the equipment surfaces. These materials are often best handled by a twin screw feeder with hopper agitation, such as Coperion K-Trons ActiFlow.
Fragile and friable materials, such as many food products and fibers must be handled carefully. Weigh belt feeders, vibratory feeders and loss-in-weight belt feeders are designed for gentle feeding of these products. Single screw feeders are also an option when configured correctly.
Without consistent, dependable feeder accuracy and repeatability for your process, the integrity of any recipe and hence the final product will be compromised. This will directly impact the system reliability, product yield and economic performance of the overall operation.
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16 Jun 2010 This is a marvellous little sizing screen i designed that runs with a small 3ph electric vibrating miller tableby Duane IdlerFeatured 20,106; 4:26 EARTHQUAKE Vibrating Gold Classifier 1by Russ Cooper 4,300 views; 7:03
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Some metals, such as copper and gold, have electronic interband transitions in the visible They occur at the interface of a vacuum and material with a small positive This has led to their use to measure the thickness of monolayers on colloid films, such as screening and quantifying protein binding events. 403, table 2.
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Specification for single phase small A/C. & universal motors b) Vibration isolation pads of suitable thickness commensurate to loading for isolation The fresh air intake shall be complete with Air Intake Louvers with insect screen, & The indoor & outdoor unit to be connected with the hard drawn copper pipe of minimum
Action Mining Services manufactures the Micron Mill Wave Table. Most importantly, recovering micron particles as small as 5 microns metals, scheelite , tantalite, stibnite, heavy mineral sands, the PGM group, copper, gold, garnets, Screening is not as critical for the M10 as it would be for the M7 therefore you can run
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It was proposed by John Bardeen, Leon Neil Cooper, and John Robert by the interaction between the electrons and the vibrating crystal lattice (the phonons). kicks from oscillating atoms in the conductor (which are small at sufficiently low of the screening currents flowing below the metal's surface) with temperature.
plates of refrigerators, park tables and chairs, housing materials (insulation), small If you lift up a TV set, you will notice that only the screen side is heavy. TVs is to take out these two kinds of glass leaving as little waste as possible. . into copper and iron by applying vibration due to the difference in specific gravity.
Favoring the use of copper in design is good practice for some very solid reasons Table 5-1 Tolerance guidelines for standard flex circuit manufacture. (Chart e addition of a small amount of length to the flex circuit beyond the design . chosen and the limits of the screen-printing materials, and (2) the processes used .
The Rock-It Portable Vibration Speaker System is a fun little gadget, provided you don't expect too much from it By Ryan Cooper, Guide Tables, lamps, glasses, dishes, beer cans (full and empty) and my face all with mixed results Paradigm Millenia 20 Trio LCR Flat Screen Speaker System Short Review
Large vibrating screens represent a unique challenge for Manufacturers, Plant Designers, and Plant Operators. The inherent mode of operation for vibrating screens is self-destructive. More often than Manufacturers admit, Designers plan for, or Operators staff for, a vibrating screen succeeds and self-destructs. This is a problem. It can magnify with larger vibrating screens.
Vibrating screen structures are subjected to nearly 250 million fatigue cycles in an operating year. The design and construction of these structures are critical in achieving reliable screen performance. Regardless of screen size, the maxims for design continue to be:
A screen design meeting these criteria yields the lowest cost per ton performance. Large screen technology is evolving more scientifically than did the development of small screen technology. As vibrating screen designs increase beyond six foot widths, reliable designs result from sophisticated engineering methods and manufacturing techniques. In addition, large screen technology amplifies the direct relationship of production cost and reliability.
Static Stresses: At rest, motionless, a vibrating screen structure is subjected to the force of gravity, at a minimum. A vibrating screen must first support its own weight. Other motionless stresses are present in the structure as a result of cutting, bending, welding, burning, drilling, assembly, tolerancing, and manufacturing variances. Quite simply, these stresses exist whether or not the screen is operating.
The second step in FEA can be considered the construction of structural loads. These include the imposition of static, dynamic, material, and fatigue conditions on the mathematical model, which approximates the load conditions. An example would be to describe a structural misalignment and the forces input co bolt up this structure through the misalignment.
Reliable vibrating screen designs are dependent upon the proper marriage of a firms manufacturing capabilities and the requirements of the design. It is not reasonable to expect that closely toleranced airframes will be successfully produced in a metal-bending job shop. As design safety factors narrow on larger screens, manufacturing techniques evolve which minimize production variables. Design tolerancing is necessarily compatible with manufacturing accuracy.
Residual metal working stress is the left-over stress in metal when melted or formed into a shape. It is a result of a materials resistance to change shape. Stress concentration sites are more commonly termed notches or stress risers. These areas are not stresses, but sharp geometric transitions or reversals in a structure. Stress loads focus their effect on a structure at these sites. Experience has proven that the methods and procedures of structural assembly can result in preloading screen bodies with excessive static stresses. The scope of this discussion is limited to the discussion of welding, forming, and bolting as they relate to conditions described above.
The side plate of a vibrating screen literally bristles with fasteners. Multi-shift production facilities, as well as maintenance crews, quickly realize the merits of this system. Unlike conventional threaded fasteners, swaged bolts exhibit a distinctly different physical appearance when installed versus loosely installed. The guess-work and wasted efforts to repeatedly insure all bolts are properly torqued are eliminated. A second-shift assembler need not consult with his first-shift counter-part regarding loose or torqued bolts . Sound maintenance practice precludes the reuse of major structural fasteners. A huck-type fastener is destroyed during removal. Normal threaded fasteners depend on proper installation torques to achieve the optimum clamping force. Registered torque wrench values may not be indicative of the true values due to the effects of thread lubrication and frictional force of the fastener face on the bolting surface. Swaged fasteners are installed strictly in tension at an optimum preset tensile load. The positive clamping values are reliably consistent. Installation error is minimal. Replaceable, non-structural components may be installed with conventional fasteners.
Anticipated operating and maintenance costs over the productive life of a processing plant design significantly influence the go or no-go decision to build the plant. Large vibrating screens can both add to and reduce the magnitude of these costs. Plant designers must examine the serviceability of these large units. This includes the complexity of installation, start-up, routine maintenance, major repairs, and operating instrumentation. In assessing these costs, the likely condition exists somewhere between the extreme of a screen leaping momentarily out of position long enough to repair itself and swarms of mechanics covering the unit like bees on honey over several production-robbing shifts.
As larger vibrating screens are used, their size will exceed cost-effective shipping limits fully assembled. Screen manufacturers will join the ranks of other major equipment suppliers in on-site assembly and testing of these units. The incremental costs associated with these efforts must be considered in evaluating the plant construction and start-up costs.
The use of larger vibrating screens results in the dependence of a larger percentage of total plant production on each unit. It is imperative that plant operators maximize the production availability of large screens. This effort is enhanced by carefully planned operating and maintenance procedures. Since volumes have been published on efficient and successful preventative maintenance programs, this discussion will not deal with that topic. There are several suggestions that can be made to help potential big screen users better position themselves to react to the service requirements of these units.
As trite as it sounds, talk to potential screen suppliers specifically about the service requirements of their screens. Determine how recently a manufacturer has entered the wide screen market. Was this entry preceded by years of research and testing? There are generally two major shortfalls in a hastily planned new product introduction. Invariably, replacement parts availability is a problem. Second is the frustrating response to a frantic maintenance question, The only guy who knows that unit is on an island in Indonesia. Solidly planned programs will have organizational depth.
The labor pains, which have normally accompanied the birth of new vibrating screen designs, have been no less severe with the gradual introduction of large, high-capacity screens. More difficulty would have been encountered without the aid of advanced engineering and manufacturing techniques.
The development of vibrating screens over the last century has seen many variations to suit the exacting requirements of industry. Indeed, as each year passes, industry has presented the challenge to screen manufacturers of supplying larger machines than those used in the past and the question is often posed what is the maximum limit?
Innovations introduced such as bouncing ball decks, heated decks, tri-sloped and bi-sloped decks and pool washing features have all sought to achieve improved anti-blinding results and improved capacity for a given screening efficiency. Although the benefits achieved by the inclusion of these features were shown in some cases to be beneficial, the application of good throw in conjunction with the required G force in the operation of the screen has proven in screen performance today, to provide maximum screening efficiency and capacity. The importance of good throw is often overlooked and should be the first consideration when wishing to maximize screen capacity.
For a straight line motion screen the throw is the distance between the extremities of motion. For a circular motion screen, the throw is measured across the diameter of motion but if the screen has an oval motion, throw is measured by taking the mean of the major and minor axes.
The throw which is specified for a particular application is determined on a screen body eccentric weight basis and normally does not take into allowance the load of material which will be handled by the vibrating screen.
Therefore it is imperative that the live weight of the vibrating screen is sufficient to maintain, within reason, the throw which has been originally specified so as to effectively handle the loads being fed to the screen.
The above comments relate essentially to a dry screening application but in wet applications where metalliferous pulp is received on the screen, the benefits of a large throw in terms of increased screen capacity have been demonstrated in commercial practice. The ideal machine for receiving pulp for wet screening or desliming, dewatering etc. is a horizontal screen. Among other reasons, the horizontal screen provides the benefit of long retention time for handling the pulp. Also the straight line motion provided with good throw imparts a positive breaking of surface tension present between the pulp and the screen deck within the apertures.
The inclusion of large vibrating screens in the design of new plants by planning engineers and metallurgists responsible for such work, particularly where large associated equipment is available, is inevitable and is in fact a progression of size we have witnessed over the years.
We should remind ourselves that size progression could not proceed without the accumulation of experience in screen body design, in application knowledge, improved quality of manufacture and refinements of mechanism design with regard to achieving improved bearing life which allows the use of a good G force.
As referenced previously G force and throw are interrelated and therefore with the good G forces available today in the modern vibrating screens, the way is clear to taking full opportunity of increasing throw to handle the high tonnages which can be expected and are currently experienced on large vibrating screens.
Where abrasion of the screen deck surface is severe as in most metalliferous mining applications, and the separation sizes are in the order of mm to 50 mm aperture sizes, polyurethane screen panels are now in common use because of their excellent resistance to wear. The trend in the use of polyurethane panels in the metalliferous mining industry is quite definite and in fact in the major mining operations in Australia at least, the use of polyurethane screening panels is firmly established.
With reference to metalliferous tailings the need for dewatering presents a new dimension. The amount of tailings produced is very much greater since some 98-99% of mined ore is rejected in tailings form compared with varying amount of 3 to 5% rejected in a coal washing operation. Furthermore with dewatering of metalliferous tailings, using equipment as mostly used in coal washing would present maintenance problems because of the more abrasive nature of the tailings and therefore for that reason it is customary to discharge all metalliferous tailings slurry to a dam.
The screen-cyclone system relies on the blinding tendency of the screen deck apertures for its success, using either stainless steel wedgewire or polyurethane deck panels in conjunction with the use of cross dams spaced every 120 cm along the deck surface. When considering the screen-cyclone system it is important to appreciate that the screen function is not one of separation at a given aperture size but bleeding of water through the restricted deck apertures caused by the semi blinding condition. That is, if the deck apertures were to remain completely free of blinding, which is not the case, practically all of the tailings would pass through the apertures in the first pass and would not allow the system to function.
The underflow from the primary cyclones should be deposited on the horizontal section of the screen deck at the feed end where the maximum of water should be removed with the assistance of an additional section of wedgewire located on a 45 inclined back plate to remove free water that has accumulated on top of the bed of slurry most solids having stratified to the deck surface. The underflow should be evenly distributed across the width of the screen at minimum velocity, so as to allow the full benefit of stratification provided by the screen.
The actual results from the initial test run taken on the pilot plant installed at Philex Mining Corporation, Philippines in March, 1980 are as follows using a gravitated flow of tailing slurry from the concentrator.
The problems involved in installing, maintaining, and operating large vibrating screens have been summarized and discussed, based on a survey of current use of such screens in selected North American mineral processing applications. Practical, effective solutions for the more serious common problems are described, along with some recommendations on design practice for specifying, selecting, and installing large screens.
In order to properly assess the information gathered through the survey questionnaire, the results pertaining to each group of applications will be presented and discussed separately in the following section. The small number of installations actually surveyed makes any rigorous statistical interpretation of the data difficult, therefore the information is presented in a generalized fashion. Notwithstanding the small sample of operations as compared to the total number of such large screen installations around the world, the results are felt to fairly represent typical operating, maintenance and installation problems and practices in the sectors of the mineral processing industry the survey covered.
The results reported in this section refer to inclined vibrating screens used in conventional crushing and screening plants. Four operations replied to the survey questionnaire, all four are medium sized producers, primarily of copper concentrate, some with significant by-product production of Mo or Ag. Daily throughputs range from 5,300 tons to 38,000 tons.
The major problem areas reported by the users of these screens were bearing failure and replacement and side plate cracking. The minor problems reported were loose bolts, seals and routine wear items such as cloth and liner changes. Reported availability of the screens ranged from 92-96%. At one operation, the crushing and screening plant is oversized and operates only one shift per day, therefore downtime for maintenance is readily available and actual availability was not reported.
The maintenance of large vibrating screens in conventional crushing applications would normally consist of the regular replacement of wear parts, such as liners and screen cloths, as well as regular lubrication of the bearings and other moving parts as recommended by the manufacturer of the particular screens in use.
The operations with large horizontal vibrating screen installations replying to the survey questionnaire were Syncrude Canada Ltd., Climax Molybdenun (Henderson Operations), Quintana Minerals and Fording Coal Ltd. As previously noted, the screen applications at these operations are all basically very similar, involving wet screening of relatively large tonnages of slurry feed.
The major problem areas with these screen installations once again include bearing failure and side plate cracking in three out of the four installations. The fourth installation, Henderson, reported major problems with the mounting springs and feed lip both of which have presently been rectified to the point where only minimal unscheduled downtime occurs.
The major problems associated with the horizontal screens were with bearings and side plate cracking, and were evident soon after commissioning. Major efforts were undertaken at all the operations to correct the serious problems.
Large vibrating screens are normally selected for applications where multiple screens would be more costly to purchase and install. There have been a considerable number of large screen installations in a variety of mineral processing applications, therefore a considerable amount of operating data with respect to the screen components and performance has been gathered. From the plant designers viewpoint the design of a screen installation should consider the following areas:
The design of a large vibrating screen installation requires close attention to not only the screen itself, but also to the ancillary structures, maintenance procedures and personnel comfort and protection.
Large vibrating screens represent a considerable investment in equipment alone. In addition the loss due to interrupted production should one of these units go out of service can be economically much more severe. As plant tonnages have risen and larger equipment has been utilized in single trains or a small number of multiple trains, the risk of having a single large screen down for any length of time has become too great to ignore.
Vibratory feeders are used in gravimetric feeding systems to handle solids with particles that are loo large to be handled by screw, rotary-vane, or vertical-gate feeders, or in operations where the physical characteristics of the solid particles would be adversely affected by passage through these volumetric feeding devices. The discharge flow pattern of a vibrating feeder is extremely smooth and thus is ideal for continuous weighing in solids flow metering applications.
The vibratory feeder consists of a feed chute (which may be an open pan or closed tube) that is moved back and forth by the oscillating armature of an electromagnetic driver. The flow rate of the solids can be controlled by adjusting the current input into the electromagnetic driver of the feeder.
The vibratory feed chute can be jacketed for heating or cooling, and the tubular chutes can be made dust-tight by flexible connections at both ends. The vibratory feeders can resist flooding (liquid-like flow) and are available for capacity ranges from ounces to tons per hour.
The Electric Vibratory Feeder is a vibratorthat provides an extremely efficient, simple and economical solution to the problem of making the most stubborn material flow freely. No longer need there be a sticking together of wet ore in the ore bin, or the arching over and hanging up of materials in hoppers and chutes with resulting lowered operating efficiency.
The powerful vibration of the simple, electro-magnetic vibrator is controlled by a separate, wall-mounted Controller, which is furnished with each vibrator. The dial rheostat in the controller varies the power of vibration. By merely turning the manual dial rheostat the power of vibration can be turned down to provide the most effective vibration required for the purpose. The controller is in a separate, dust-proof housing, arranged for wall-mounting at any desirable distance away from the vibrating mechanism attached to the bin, hopper, or chute.
These vibrators are furnished in many different sizes. Units are available that range from those equipped to handle large tonnages in ore bins down to the small noiseless model best suited to be attached to a dry reagent feeder. Reagent feeder applications are numerous, but a well-known use is where the vibrator is utilized to keep moist lime or soda-ash stirred up and flowing evenly.
In an ore bin with a flat bottom and a center discharge, the material, especially when wet, will build up in the corners and form a dead storage space just inside the walls of the bin. One or two vibrators mounted on the outside of the ore bin (opposite to each other, when two are used), will eliminate the work that otherwise frequently has to be done by hand with a pick and shovel. Another, and possibly more important aspect, is that maximum treatment efficiency is assured by an even feed to crushers or ball mills.
These vibrators are also available at extra cost with totally-enclosed explosion-proof, or water and dust-proof cases. Also, for special jobs where danger of explosion or fire exists, a water or air-pressure vibrator can be furnished. A major advantage of these hydraulic vibrators over electricvibrators is that they can be made to run at a slow speed as well as at a high speed (2400 to 4800 vibrations per minute).
The flow velocity depends on the method for loading the feederis it fed through a hopper? The velocity is also dependent on the material characteristics, size distribution and moisture content, as well as the slope of the feeder. The only way to determine the value for v is by actual observation and then the feeding rate may vary considerably.
Feeders are used to provide and control the flow of bulk solids to the process from storage units, such as bins, bunkers, silos, and hoppers. In to-days fully instrumented process plants, it is mandatory that feeders maintain a uniform flow of material at the rate set by signals from process equipment farther downstream in the flow. Large variations in feed, due to feeder blocking, arching or ratholing in the bin, may completely defeat the purpose of such a sophisticated control system with all its planned advantages to the process.
Most of the bins used in the mining and metallurgical industry to-day are of the plug flow type, as they are suited for the storage of hard, abrasive or coarse materials. Exceptions are the ore concentrate or fine powder bins which usually are of the mass flow type.
Plug flow occurs in bins or hoppers with flat sloping walls and is characterized by the flow of solids in a vertical channel extending upward from the bin outlet. Plug-flow bins are suited for solids which are free flowing, do not deteriorate with time and in which segregation is of no importance. As flow does not occur at the bin walls, this type of bin is useful for the storage of hard and abrasive materials. The drawbacks of this type of flow, however, are as follows:-
a) The live bin capacity of the bin is drastically reduced. b) The bin is not self-cleaning and usually cannot be emptied by gravity flow. c) Materials which deteriorate with time cannot be stored in this type of bin. d) The flow is erratic and non-uniform, as solids flowing through a vertical channel with a constant cross section tend to form arches which collapse and compact the material below, thus causing arching again. e) This type of flow pattern in the bin aggravates the segregation of particle sizes.
In many instances, hopper openings are large enough to prevent arching: however if the hopper is not designed for mass flow, piping or ratholing may occur. In plug flow bins, the material flows in the centre of the bin, into which the sides slough as the material is drawn from the bin. Reaching a certain level in the bin where the material has time to consolidate, sloughing will cease and a steady channel or rathole (limited flow) will form, drastically reducing the bins live capacity. In mass flow bins, channelling can also occur if the feeder does not draw the material uniformly across the whole area of the feed opening.
To overcome flow problems, flow-promoting devices such as external vibrators, pneumatic air panels, air jets and vibrating internal structures are usually installed. These relatively inexpensive devices can solve the problem in marginal cases. However, where the costly complete re-design of bins or hoppers is indicated by bulk solids flow calculations, other apparently less costly ways for improvement are usually sought.
The extension of the mine workings under adjacent lakes for the reach of the recently found copper ore body, and the introduction of sand fill underground in the past years using the mill tailings, led to build-up of the moisture content of the fine ore. In the meantime, the 50% increase of daily mill output from the original 2000 to 3000 tons necessitated finer fourth stage crushing and the addition of an extra grinding mill. The fine ore actual handled to-day is a roll-crusher product of -5/32 in size with a moisture content of 2% to 3%.
The fine ore bin, as originally conceived with its wear angles on the sloped walls, is of the plug-flow type. It performed satisfactorily in the earlier stages of operation of the plant when the material handled was coarser and lower in moisture content. With increasing ore moisture and material fineness, however, the live capacity of the fine ore bin was gradually reduced to a point where, in some instances, only channelling or ratholing occurred over the feed openings.
After visiting installations using long belt feeders, consideration was given to the use of the existing gathering conveyors as belt feeders. This scheme involved the cutting of long slots into the bin bottom above the entire length of the existing belts.
The flow pattern in a flat bottom bin with single or multiple openings is usually of the plug-flow type. The drawbacks of this type of flow have been explained previously. It was felt, however, by the author that improvements could be made by the appropriate location of feed openings and by the use of suitable feeders. The basic idea for this improvement was initiated by the review of the results of model tests performed on flat bottom bins, which indicate a mass flow type of pattern at the beginning of the bin discharge. This pattern switches gradually to plug flow as the material level drops below a certain point. This partial mass flow situation can prevail only if the material handled is reasonably free-flowing, the feed openings are sufficiently closely spaced, and the material is drawn uniformly from each opening.
The example illustrated is taken from an iron ore concentrator, and shows the arrangement in which the mill feed conveyor is receiving material from the gathering belt located underneath the two silos. The fine ore handled is taconite, -5/8 in size, and a tertiary cone crusher product with 1 to 2% moisture.
When drawn empty, the dead material left in the bin generally takes the form of a wedge-shaped hopper. However, the slope of the material should not be mistaken for the angle of repose , as it is really the included half angle e of the flow channel, which is usually much steeper due to material consolidation. Approximate expected values of e can be calculated knowing the flow properties of the material handled.
In the mineral processing area, the trommel screens(aka. Rotary drum screens) and vibrating screens are both widely used screening & classification equipment. But whats the difference between the trommel screens and vibrating screens, and how to choose the most suitable screens for your mineral processing application? Or even how should we choose the right screening equipment for specific mining conditions?
Thorough we all may know that they are both are widely used screening equipment, but the different working methods and principles also mean the difference in output, as well as the types of materials suitable for screening processing.
Vibrating screens are screened using the exciting force generated by a vibrating motor and belong to vibrating screens. Commonly used mine vibrating screens include circular vibrating screens and linear screens.
The trommel screen is another screening form. During the screening process, the equipment will not vibrate, but generally, the motor and reducer drive the drum to rotate through the bearing. The material in the drum passes through the screen from high to low due to the rotation of the drum. And it is successfully screened out, so the trommel screen belongs to a type of rolling screening.
trommel screen: It is a cylinder. The outer surface of the cylinder uses one or more layers, or several sections of screens to increase the screening specifications. The volume of the trommel screen is generally large, mainly including motors, reducers, drum devices, screens, and machines. It is composed of a frame, a sealing cover, and an inlet and an outlet. A steel ring must be added to the drum device to prevent the trommel screen from deforming.
The roller device is installed on the frame obliquely. The motor is connected with the roller device through a coupling through a reducer, and drives the roller device to rotate around its axis. When the material enters the drum device, due to the tilt and rotation of the drum device, the material on the screen surface is turned and rolled. The qualified materials (products under the screen) are discharged through the outlet at the bottom of the rear end of the drum, and the unqualified materials (on the screen) The product is discharged through the discharge port at the end of the drum.
Using the vibration motor as the vibration source, the material is thrown up on the screen while moving forward in a straight line. The material enters the inlet of the screening machine evenly from the feeder, and produces several kinds of screens through the multi-layer screen. The upper and lower objects are discharged from their respective outlets.
The screen surface is fixed on the screen box, and the screen box is suspended or supported by springs. The bearing of the main shaft is installed on the screen box and is driven by the pulley to rotate at high speed. The eccentric counterweight plate is installed on the main shaft and generates centrifugal inertia force with the rotation of the main shaft, so that the screen box forms an approximate circular orbit vibration.
The trommel screen can be divided into single-layer, double-layer and three-layer vibrating screens according to the number of layers of the screen. This vibrating screen is also similar, according to the number of screen surface layers can be divided into single-layer, double-layer, three-layer and four-layer vibrating screen.
The vibrating screen is a screening equipment with a vibrating motor as the vibration source, so the screening accuracy is high. The trommel is a high-output screening equipment, and the screening accuracy is not as high as the vibrating screen.
For the trommel screen, the material is turned over and rolled in the drum, so that the material stuck in the sieve hole can be ejected to prevent the sieve hole from being blocked. For the circular vibrating screen, the material moves in a parabolic circular trajectory on the screen surface, so that the material is dispersed as much as possible to improve the materials bounce force, and the material stuck in the screen hole can also jump out, reducing the hole blocking phenomenon.
Vibrating screen and trommel screen have their own working methods and screening principles. Some raw materials can be screened through them. However, for different sites and different material requirements, suitable screening machines should be selected to achieve better screening results.
KP Series Round vibrating screen is a high precision fine powder sieving machine. The fundamental principle of round vibrating screen is that the eccentric hammers installed on the top and bottom ends of motor changes the rotation motion of motor to horizontal, vertical and inclined three-dimensional motions, and then passes this motion to screen surface, achieving the purpose of classification, filtering and removal of impurities.
3.Metals, metallurgy and mining: aluminum powder, lead powder, copper powder, ore, alloy powder, welding rod 4.powder, manganese dioxide, electrolytic copper powder, Electromagnetic material, grinding powder, refractory materials, kaolin, lime, alumina, heavy calcium carbonate, quartz sand, etc.
Prominer maintains a team of senior gold processing engineers with expertise and global experience. These gold professionals are specifically in gold processing through various beneficiation technologies, for gold ore of different characteristics, such as flotation, cyanide leaching, gravity separation, etc., to achieve the processing plant of optimal and cost-efficient process designs.
Based on abundant experiences on gold mining project, Prominer helps clients to get higher yield & recovery rate with lower running cost and pays more attention on environmental protection. Prominer supplies customized solution for different types of gold ore. General processing technologies for gold ore are summarized as below:
For alluvial gold, also called sand gold, gravel gold, placer gold or river gold, gravity separation is suitable. This type of gold contains mainly free gold blended with the sand. Under this circumstance, the technology is to wash away the mud and sieve out the big size stone first with the trommel screen, and then using centrifugal concentrator, shaking table as well as gold carpet to separate the free gold from the stone sands.
CIL is mainly for processing the oxide type gold ore if the recovery rate is not high or much gold is still left by using otation and/ or gravity circuits. Slurry, containing uncovered gold from primary circuits, is pumped directly to the thickener to adjust the slurry density. Then it is pumped to leaching plant and dissolved in aerated sodium cyanide solution. The solubilized gold is simultaneously adsorbed directly into coarse granules of activated carbon, and it is called Carbon-In-Leaching process (CIL).
Heap leaching is always the first choice to process low grade ore easy to leaching. Based on the leaching test, the gold ore will be crushed to the determined particle size and then sent to the dump area. If the content of clay and solid is high, to improve the leaching efficiency, the agglomeration shall be considered. By using the cement, lime and cyanide solution, the small particles would be stuck to big lumps. It makes the cyanide solution much easier penetrating and heap more stable. After sufficient leaching, the pregnant solution will be pumped to the carbon adsorption column for catching the free gold. The barren liquid will be pumped to the cyanide solution pond for recycle usage.
The loaded carbon is treated at high temperature to elute the adsorbed gold into the solution once again. The gold-rich eluate is fed into an electrowinning circuit where gold and other metals are plated onto cathodes of steel wool. The loaded steel wool is pretreated by calcination before mixing with uxes and melting. Finally, the melt is poured into a cascade of molds where gold is separated from the slag to gold bullion.
Prominer has been devoted to mineral processing industry for decades and specializes in mineral upgrading and deep processing. With expertise in the fields of mineral project development, mining, test study, engineering, technological processing.
Vibrating screen is mainly used for continuous and uniform feeding in front of the coarse crushing crusher, and at the same time, it can screen fine materials to increase the crusher processing capacity.Applicationsin the crushing and screening equipment of metallurgy, coal mines, beneficiation, building materials, chemicals, abrasives and other industries.MaterialRiver pebbles, granite, basalt, iron ore, limestone, quartz, coal, gangue, construction waste, etc.
Frameprotected by guard plate, the main unit is convenient for maintenance and allows extended service life.Isolation bearingsare protected by rubber, less wear and noise.Oil indicatorconvenient for customers to check the lubricating oil.Gearswith high strength and high precision can ensure the reliable operation.Motorare all famous brands, customers can assign the specific brands like Siemens.Grid clearance (screen bar)be adjusted according to working conditions; replaceable guard plates for the grid are convenient for maintenance.
Also the feeder can be divided into a steel plate structure and a grid structure.The feeder with a steel plate structure is mostly used in a sand and gravel production line to uniformly feed the material into the crushing equipment.The feeder with a grid structure can roughly screen the material. Make the system more economical and reasonable in the preparation, has become an indispensable equipment in crushing and screening.