mining processing spiral classifier in nigeria

spiral classifier for mineral processing

spiral classifier for mineral processing

In Mineral Processing, the SPIRAL Classifier on the other hand is rotated through the ore. It doesnt lift out of the slurry but is revolved through it. The direction of rotation causes the slurry to be pulled up the inclined bed of the classifier in much the same manner as the rakes do. As it is revolved in the slurry the spiral is constantly moving the coarse backwards the fine material will flow over the top and be travelling fast enough to be able to work its way downwards to escape. The Variables of these two types of classifiers are The ANGLE of the inclined bed, this is normally a fixed angle the operator will not be able to adjust it.

The SPEED of the rakes or spirals, the DENSITY of the slurry, the TONNAGE throughput and finally the SETTLING RATE of the ore itself.To be effective all of these variables must be balanced. If the incline is too steep the flow of slurry will be too fast for the rakes or spirals to separate the ore. If the angle is too flat the settling rate will be too high and the classifier will over load. The discharge rate will be lower than the feed rate, in this case. The load on the rakes will continue to build until the weight is greater than the rake or spiral mechanism is able to move. This will cause the classifier to stop and is known as being SANDED UP. If the speed of the rakes or spirals are too fast, too much will be pulled, out the top. This will increase the feed to the mill and result in an overload in either the mill or classifier as the circuit tries to process the increased CIRCULATING LOAD.

The DENSITY of the slurry is very important, too high the settling will be hampered by too many solids. Each particle will support each other preventing the heavier material from quickly reaching the bottom of the slurry. This will not allow a separation to take place quickly. The speed at which the slurry will be travelling will be slow and that will hamper effective classification. Another variable is the TONNAGE. All equipment has a limit on the throughput that anyone is able to process, classifiers are no different. This and the other factors will have to be adjusted to compensate for the last variable, the ore itself. Every ore type has a different rate of settling. To be effective each of the previous variables will have to be adjusted to conform to each ones settling characteristics.

The design of these classifiers (rake, spiral, screw) have inherent problems, First, they are very susceptible to wear, caused by the scrubbing action of the ore, that plus all of the mechanical moving parts create many worn areas to contend with. The other problem that these classifiers have is that they are easily overloaded. An overloaded classifier can quickly deteriorate into a sanded-up classifier. Once that happens the results are lost operating time, spillage and a period of poor Mineral Processing and Separation performance.

Another mechanical classifier is the spiral classifier. The spiral classifier such as the Akins classifier consists of a semi-cylindrical trough (a trough that is semicircular in cross-section) inclined to the horizontal. The trough is provided with a slow-rotating spiral conveyor and a liquid overflow at the lower end. The spiral conveyor moves the solids which settle to the bottom upward toward the top of the trough.

The slurry is fed continuously near the middle of the trough. The slurry feed rate is so adjusted that fines do not have time to settle and are carried out with the overflow .liquid. Heavy particles have time to settle, they settle to the bottom of the trough and the spiral conveyor moves the settled solids upward along the floor of the trough toward the top of the trough/the sand product discharge chute.

types of classifiers in mineral processing

types of classifiers in mineral processing

In mineral processing, the Akins AKA spiral or screw Classifier has been successfully used for so many years that most mill operators are familiar with its principle and operation. This classifier embodies the simplest design, smallest number of wearing parts, and an absence of surge in the overflow. It separates coarse and fine solids, carried in liquids, with a high degree of accuracy and with lowest possible power and maintenance costs. Additional information on Akins Classifiers will be sent upon request.

If the pulp (solids and liquid) contains more than 5% of solids larger than 48 mesh, the type 40 Allen Sand Cone is almost always used, where as if the solids contain less than 5% coarser than 48 mesh it is generally advisable to install the type 50 Slime Cone.

The feed enters the cone through an inner truncated cone, settled solids gradually building up in the cone to a point restricting the out-flow of the inner truncated cone. This causes the water level in the truncated cone to rise lifting a float which operates a series of levers to operate a ball valve to open a spigot in the bottom of the cone which discharges the settled material. This arrangement maintains an even depth of sand regardless of increase or decrease in the feed rate. If a foreign object should obstruct the opening retarding the flow the valve opens wider, thus allowing the passage of the obstruction.

The operation of the Allen Slime Cone follows the same general principle as described above except the float is located near the bottom of the cone and is operated by the buoyancy of the settled slime. The float operates a ball valve and spigot same as for the sand cone.

CONE Classifiers are built in two types, one operating on the density of the pulp in the cone, and the other on the hydraulic or mechanical movement of the pulp. The Dewatering Cone is of the former type. The weight of the pulp in the cone actuates a lever with an adjusting weight, automatically controlling the discharge valve. This method gives a constant density discharge. The unit can be used as either a dewaterer or classifier, requires no power, and is entirely automatic.

The body of the separator can be conical or pyramidal in shape, to suit best the physical requirements of the location. The classifier can be used to advantage in dewatering and controlling feed to a regrind ball or rod mill, or material from tables, jigs, or flotation.

CLASSIFIERS having a helical (often improperly called spiral) flight for removing settled coarse material have long been in successful use and most mill operators are familiar with their operation. The Cross-Flow Classifier is of this general type but has many improvements which result in improved metallurgical efficiency, longer life and less repair. Among these improvements may be mentioned:

An auxiliary weir is provided at the end of the classifier. Both the main and auxiliary weirs are provided with weir blocks by which the depth of the pulp and pool area may be adjusted, thus controlling the size of separation.

The Cross-Flow Classifier is ruggedly constructed and the tank is thoroughly reinforced. Bearings are Jarge and all gears are enclosed. The 6, 9, and 12 sizes have replaceable hard cast iron flight sections on a square shaft. The 18, 24, and 30 have replaceable hard cast iron flight sections. The 36, 42, 48, 54, and 60 sizes have replaceable steel flights and replaceable hard iron wearing shoes. Sizes 30 and larger are provided with lifting device by which the lower end of the flight may be raised and the conveyor operated while it is slowly lowered, thus gradually removing the bed of solids which settles during a shutdown.

Hydraulic Classifier is designed for use in gravity concentration mills for preparing a classified feed for table concentration. The classifier compartments are provided with glass sides so that the conditions existing in each chamber can readily be observed. Only enough water is necessary to keep the solids in full teeter. As the sands accumulate in the classifier pockets the effective density of sand-water mixture increases and thumbscrews onthe valve rod assemblies may be adjusted to discharge sand fromeach compartment as required. The finer the sand the less water is required. When the pressure regulating valves and the product valves are set, no further adjustment is necessary.

The Hydraulic Classifier is made in 2, 4, 6, and 8 compartments with two sizes of compartments, namely 4x 4 and 8x 8. The standard units are of steel construction. Capacity depends on specific gravity of the material and range of size taken from each compartment. The 4x 4 has a capacity from 5 to 10 tons per compartment in 24 hours. The 8x 8 has a capacity from 20 to 50 tons per compartment in 24 hours. Additional data gladly furnished upon request.

TheHydroclassifieris designed to make a separation according to size in the range from 100 mesh to that of colloidal particles. It is particularly suited to the removal of slimes prior to further treatment by flotation, cyanidation, or chemical processes. The separation in this fine size range requires a large quiet, pool area, such as isprovided by the Hydroclassifier, combined withaccurate control over the removal and washing of thesettled material for maximum classification efficiency.

In the Hydroclassifier the feed enters a feed well in the center of a large settling tank and flows without agitation into the pool. The slimes and fine material move radially to the overflow weir at the rim of the tank and overflow into the overflow launder. As the slimes move to the weir, the coarse particles settle on the sloping tank bottom, where slowly moving spiral rakes continuously move these settled solids to a central discharge cone. In the discharge cone water is added below a perforated plate while the settled solids are rabbled above the plate, thoroughly washing out slimes and fines from the coarse material, as it works through the openings in the plate. The coarse material is usually removed in the form of a sludge by means of a Adjustable Stroke Diaphragm Pump.

The tank is steel, thoroughly reinforced, and supported on steel columns, thoroughly braced. The mechanism driving the rakes is an alloy steel gear and bronze worm, supported on anti-friction bearings enclosed and running in oil. The vertical shaft and rakes may be raised or lowered while the mechanism is in operation. Extra heavy construction is provided throughout, resulting in long life and a minimum of repair. Additional data gladly furnished upon request.

In addition to these standard machines we can furnish larger sizes where mechanism is placed in customers concrete tanks. Mechanism sizes 22 to 40 can be furnished for concrete tanks. These sizes can be furnished in Bolted Steel Tanks. Capacity range depending on mesh separation, specific gravity and per cent solids in products. Horsepower depends on the amount of solids settling and specific gravity.

The Rake Classifier is designed for either open or closed circuit operation. It is made in two types, type C for light duty and type D for heavy duty. The mechanism and tank of both units are of sturdiest construction to meet the need for 24 hour a day service. Both type C and type D Rake Classifiers have a tank made of heavy steel plate with the seams double electric welded both inside and out. Tanks are arranged so that feed may enter from either side. Rakes are made either of heavy steel angles welded to channel supports which are carried by the actuating mechanism or channel irons split lengthwise and welded to supports, whichever type of duty the classifier will be expected to perform. Raking movement is accomplished by a cam and roller drive. Cams are mounted on an oversize shaft and driven by a semi-steel cast tooth gear and pinion on the light duty unit or heavy molychrome steel cams operated by machine cut gears are used on the heavy duty unit. Mechanism supports are of the strongest possible construction and have a large safety factor to withstand severe load conditions. Also, the babbitted pillow block drive bearings on the light duty unit and the bronze bushed drive bearings on the heavy duty unit are of ample size to handle most any overload condition.

A rake lifting device, utilizing worm gears, a hand crank, and steel cables, is provided on both units and this rake lifting device is so designed that one man can quickly and easily raise or lower the rake. Classifiers can be furnished either belt or motor driven. On the belt driven type a right angle drive can be supplied if desired. The standard motor drive is V to flat with 3-phase, 60 and 50 cycle, 220, 440 or 550 volt motor.

The standard length of C type simplex classifier is 148, with widths of 16, 20, 23, 30. Type C duplex standard lengths are 120, 148, 164 and 180, with widths of 40, 46, 50 and 60. Model D simplex has tank lengths of 184, 20,0, 218, 234, 250, or 268, with width of 30 and 40. Heavy duty model D duplex comes with tank lengths the same as model D simplex, and widths of 50, 60, 70 and 80.

The Rotary High Weir Classifier is designed to give best classification of fine and coarse material. The horsepower is low and maintenance is reduced to a minimum. The classifier is made with either a high or low weir, the highweir with its larger pool areabeing used where a fine separation is necessary. Rotary High Weir Classifier is built with replaceable wearing flights, steel tank mounted on base, and belt or gear-motor drive. Standard drive is a single bevel gear, although spur gear and double reduction drive units can be furnished.

The two conveyor shaft bearings are mounted outside ofthe tank away from pulp and splash. The conveyor shaftis effectively sealed at the slime overflow end of the tankby means of a specially designed stuffing box which contains a distributing ring in addition to the conventional packing rings. Admission of water to the interior of the stuffing box prevents any dirt from entering. This classifier can also be made of corrosion-resisting material so as to handle successfully products such as sulphuric acid.

5tph hard quartz rock gold mining process in nigeria - jxsc

5tph hard quartz rock gold mining process in nigeria - jxsc

Material: Hard rock gold deposit Capacity: 5TPH Country: Nigeria Feeding size: 0.6-1.3mm Raw mineral description: 1. Mineral type: rock gold deposit, gold in quartz rock 2. Mineral composition: Au. 43%; Ag. 19%; Fe. 3%; Zn. 5.6%. Customers requirements: increase the gold grade as much as possible.

JXSC has been focusing on mining equipment manufacturing since 1985. Products: rock crushers, gravity separator, electrostatic separator, flotation machine, washing equipment, ore feeder, screen & sieve, etc. Application: metallurgical, mineral processing, sand making, aggregate processing, etc. Contact us for quotation

Notes: 1. Services (installation, test run, training) : the supplier can provide basic drawings and schematic drawings of equipment installation. The domestic technicians will be provided for free to guide installation and debugging, and the buyer will provide technicians with room and board. The buyer shall prepare necessary auxiliary materials for installation. 2. Quality guarantee: the equipment is guaranteed for one year. In the warranty period, due to the quality of the product manufacturing, manufacturers free warranty (except wearing parts).

spiral classifier - mineral processing

spiral classifier - mineral processing

Spiral classifier and hydrocyclone are the main equipments for the classification operation of the concentrator. Although the rapid development of the cyclone once made the spiral classifier lose its market, but with the continuous changes in the requirements of the selection plant, it was found that the spiral classifier also has its advantages. The spiral centrifugal classifier has the advantages of strong continuous operation, large processing capacity, low energy consumption per unit output, and convenient maintenance. It can handle particles with a diameter of 1um-10mm. The horizontal spiral centrifugal classifier adopts the method of wet classification, and its processing capacity can reach 1~20 (m3 slurry) kg/h. It is widely used in minerals, metal powders, chemical raw materials, pigments, fillers, etc.

The screw classifier is based on the principle that the solid particles are different in size and specific gravity, so the settling speed in the liquid is different. Fine ore particles float in the water and overflow, and coarse ore particles sink to the bottom of the tank. Spiral classifier is widely used in beneficiation plant to match with ball mill to form a closed circuit circulation path to distribute ore sand. Filter the material powder milled in the mill, and then use the spiral piece to screw the coarse material into the ball mill inlet, and the filtered fine material is discharged from the overflow pipe. There are four classifiers: high weir single spiral and double spiral, submerged single spiral and double spiral.

The spiral classifier is widely used in the classification of the grinding circuit of the concentrator and the operations of washing, desilting and dewatering. Its main advantages are simple equipment structure, reliable work and convenient operation.

1. It is used for the separation of machine-made sandstone powder, which can control the content of machine-made sandstone powder very conveniently and meet the requirements of users.2. It is suitable for dry technology large and medium-sized sand production lines.3. The content of 0.000.75mm stone powder can be adjusted between 2%-15%.4. Stone powder quality is easy to control, fineness adjustment is convenient, flexible and reliable.5. Using frequency conversion control technology, the operation is more concise.6. It can be connected with the mill in the closed circuit of the grinding circuit. Compared with hydrocyclone, the power consumption is lower.7. The main disadvantage is that the classification efficiency is low, the equipment is bulky, and the floor space is large. Due to the limitations of equipment specifications and production capacity, it cannot generally form a closed circuit with a ball mill of 3.6m or more.

The spiral classifier is divided into two types: high weir type and submerged type. High weir classifier is suitable for coarse particle classification, the maximum size of overflow is generally 0.4~0.15mm; submerged classifier is suitable for fine particle classification, the maximum size of overflow is generally below 0.2mm.

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