spiral classifier times

spiral classifier of stable performence | fote machinery

spiral classifier of stable performence | fote machinery

Applied materials: in the metal beneficiation process including gravity concentration and ore washing of the materials such as quartz, gold ore, iron ore, copper ore, ore, ore pulp, fine mud, cement clinker, magnetite, etc.

Coarse particles sink to the bottom of the tank and are conveyed by the screw to the discharge port to be discharged. Generally, the coarse sand is returned to the ball mill for secondary grinding, that is, the spiral classifier and the ball mill form a closed circuit.

It is composed of the hollow shaft, bracket, spiral blade, lining iron, etc. The hollow shaft is welded by seamless steel pipe, journal and flange. Wear-resistant life is the key in use, so the lining iron is made of wear-resistant materials.

It is easy to wear, for its long-term immersion in the slurry. Therefore, frequent maintenance and replacement are its main characteristics. For this, the spiral classifier adopts the structure of movable shaft sleeves and nylon bearing bushes.

When the shaft sleeve and bearing bush are worn out, a new set of sleeve and bush can be replaced ten minutes after the screw is lifted by the lifting mechanism, which is convenient for maintenance and replacement.

It is welded by steel plates and various section steels. The foundation construction of the tank is very important because it contains all the slurry and bears the weight of the whole body and all the load.

In order to discharge slurry from the water tank when necessary, a water drain valve is installed in the lower part of the tank, which can discharge the slurry at any time and can be closed during normal production.

The settlement area of this kind of classifier is large and its weir height can be adjusted within a certain range, that is, the area of the settlement area can be adjusted and changed within a certain range.

It has a small settlement area and low overflow production capacity, so it is mainly suitable for ore classification with an overflow particle size of 0.15-0.07 mm. It is also used to wash ore for desliming.

Model description: Take "2FG-15" as an example, "2" means double spiral, the single spiral is not marked; "F" means spiral classifier, "G" means high weir type and "C" means submerged type; "15" indicates the spiral diameter of the classifier, in dm.

If the grinding fineness is required to be finer, angle irons of a certain height can be welded on both sides of the classifier, and the level of the classifier overflow weir can be adjusted by the method of inserting wood. Sometimes the overflow weir can be naturally increased after a long-term accumulation of ore mud.

To obtain coarse overflow, the speed of the spiral with a diameter of 2 m should not exceed 6 r/min, and with a diameter of 1 m or more should be controlled at 2-8 r/min. For example, for a spiral with a diameter of 0.3 m, in order to obtain a coarse overflow, the spiral speed can be increased, but it cannot exceed 25 r/min.

If the screw pitch is short at the overflow end and long at the sand return end, the amount of sand return can be increased and stable agitation at the overflow end can be ensured, which is convenient for improving the overflowing quality and processing capacity.

The width of the grading tank has little effect on the grading effect, but is closely related to the processing capacity of the grading machine. The larger the tank width, the larger the processing capacity. On the contrary, the processing power is small.

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screw classifiers

screw classifiers

To be successful in a obtaining a uniform grind that is necessary to achieve a high percentage of recovery it is necessary to control the degree of fineness that the ore is reduced to. This is done by separating the fine material from the course and regrinding the coarse until it is fine enough for efficient mineral extraction.

To be able to obtain the necessary control over the amount of grinding required, a method of effective classification and separation by size must be available. For maximum effectiveness it should take place after every stage of grinding.

The types of equipment that are used to accomplish this are called CLASSIFIERS. There are three basic kinds used. The first two, the RAKE classifier and the SPIRAL or screw classifier work on the same principal, and are not often used any more. These two types were popular for many years. It wasnt until the development of the CYCLONE type classifier that their popularity faded. You may still find a few though, in the older mills and the mills that require a classification of the larger ore sizes that the cyclones are not very good at sizing. Both the rake and spiral classifiers take advantage of the natural settling characteristics of ore. Any time that slurry is allowed to flow over a surface the tendency of the ore is to graduate itself into layers of different sized material. The larger sizes will be on the bottom, these are also the ones that are the slowest moving. As you come closer to the surface, the material will become smaller and faster until the very finest and the easiest to wash away is on top.

To understand how these two classifiers make use of this settling action, a description of them is required. First, to have the classification happen, the slurry must be able to flow. This means the classifiers must be inclined. The working portion of these two classifiers are the RAKES or SPIRAL/screw which are placed into the flow of ore. To separate the course material from the fine, the rakes and spiral make use of the same theory, but differ in its application. The theory is, as the slurry flows down the inclined bed of the classifier it will separate into different sizing. The larger ore that is on the bottom will not be flowing as fast as the light ore on top.

To separate the two, the rakes and the spiral will pull the all of the slurry back up the incline, then, let it go to flow back down towards the underflow or in this case the fine ore discharge point. The smaller, faster ore will be able to travel a longer distance than the large particles before the rakes or spiral will pull the ground material back towards the coarse ore discharge. If the Classifier is able to pull the course ore backwards further than it can travel forwards, then eventually the bigger particles will be pulled all the way to the top of the incline where they will be discharged. The smaller faster pieces of ground rock will end up at the bottom of the incline to be discharged as fine material that is ready for the next stage of processing.

This type of classifier will do away with the necessity of pumps. The length of the incline that is needed is long and steep enough to have the material lifted to the feed end of the mill. The flow of the finer ore will run down hill to the next piece of equipment. The concentrator that used this type of classification was built on the side of a hill to make use of gravity to get the material from one stage of production to the next. It was because of this that this type of concentrator was referred to as a GRAVITY FLOW/MILL. I used the past tense in this paragraph because this design of mill is no longer in use.

I want to know what is the range of the % Solids content in overflow from screw/spiral classifier in Hematite Iron ore washing for efficient operation of classifier. I also want to know what is Auto dilution in thickener. Does Auto dilution has any effect on Pumping capacity of clarified water from thickener.

Each operation is different, but the good news is that you can simply determine the solids % wt. in the SOF, try 2 -3 times daily over one week, get a profile. If below 5% wt., you may not need auto dilution, also depending on ore and grind size. This is almost a clarifier regime, often workable without rakes in certain units. Above 5% in general start looking at auto-dilution before adding the flocculant do this off-line. Make sure that the thickener underflow (TUF) discharge comes out continuously, otherwise you may need to play with the lifters, if you have them. The UF solids % wt. must be correlated with the yield stress.look for 30 Pa high-end cut off value for lean operation. When the ore or grind size changes, you need to repeat the evaluation.

My take on these classifiers is that the clear water added to the classifier feed determines the size of the largest heaviest particle going to the overflow. This is the criteria that you should be working to achieve. As you probably have more than one classifier reporting to the thickener you will need to perform the solids percent in each overflow. As you add water to the classifier feed, the separation efficiency increases. You should be raising or lowering the discharge weir to attain the desired size cut. Only if the thickener becomes overloaded should you add water. Pumping excess water adds cost and wear to pump trains.

Pulp density of the Overflow defines % of solids in thickener. This solids% depends also up on quality of recycle water used in spiral processto know quantum of solids..you have to give feed quantity and underflow quantity.

The % solids in classifier overflow may vary in wide range, its all depends on your ore characterisation and operating variables. For the same operation we used to get 15-18% solids as my ore contains too much fines & this is not end process in our case.Try to concentrate on end products. Do not let go valuables in your final tailings.

henan seasun heavy industry machinery co., ltd

henan seasun heavy industry machinery co., ltd

Copper ore dressing equipment Scope: Weakly magnetic minerals beneficiation, for example: hematite, limonite, ilmenite, wolframite, tantalum, niobium, etc.. Non-metallic minerals deironing, purification, for example: quartz, feldspar, nepheline, fluorite, sillimanite, spodumene, kaolin. Two common copper ore flotation process: 1. dye-shaped copper ore flotation process Generally use relatively simple process, after a period of grinding, fineness -200 mesh occupy about 50% to 70%, once roughing, two or three times selected, one or two times scavenging. Such as disseminated copper minerals has relatively small size, consider to adopt the stage grinding and separation processes. Processing bornite concentrator, mostly coarse concentrate regrinding - a selection of stage grinding and separation processes, and its essence is mixed - flotation process. First by a coarse grinding, roughing, scavenging, and then rough concentrate regrinding recleaner get high-grade copper concentrate and concentrate. Rough grinding -200 mesh about 45% to 50% and then pulverized -200 mesh occupy about 90% to 95%. 2. Dense copper ore flotation process Dense copper ore chalcopyrite and pyrite as tight symbiosis, pyrite is often secondary copper-activated pyrite content is high, difficult to suppress, sorting difficult. Sorting process requires both get copper concentrate and concentrate. Typically election of copper tailings is pyrite concentrate. If the ore gangue content of more than 20% to 25%, sulfur concentrate needed sorting again. Dense copper ore processing, often using two stages of grinding or grinding, fine grinding fineness requirements. Amount of reagent is also larger, xanthate dosage 100g / (t raw ore) above, lime 8 ~ 10kg (t raw ore) above. Copper ore beneficiation process: 1. crushing part: basic process of ore crushing process. Its purpose is to crush ore to an appropriate size, suitable for grinding part. 2. Grinding part: Part grind ore processed further to get a smaller size, to match up flotation separation material. 3. flotation sections: the flotation process / upgrade Copper important process. Chemicals are added to the mixer / blender, to make chemical reaction. Copper ore dressing plant: Mining ores first by the jaw crusher for preliminary broken, in broken to a reasonable fineness through ascension machine, after to mine machine uniform into ball mill, ball mill by crushing, grinding of ore. After grinding ball mill of ore materials into the next procedure and: grading. Hierachial machine with different proportion of solid particles in the liquid and the speed of the precipitation different principle of minerals, the mixture to wash, grading. After a wash and classification of the mineral mixture after magnetic separation unit. Because of various minerals than magnetized coefficient of different magnetic force and, by mechanical force will mixture of magnetic material separated. After magnetic separators preliminary after the separation in mineral grains was sent into the flotation machine, according to different mineral properties of different drugs, make to the minerals and other material separation open. Desire to minerals is isolated, because its a lot of moisture, must be approved by the initial concentration concentrating machine, then through the dryer drying, you will get dry minerals. Copper fine powder grade reached 45%. 200t/d Copper Ore Beneficiation Equipment: Device name Specifications Motor Power kw Number set Jaw crusher PE-400600 30 1 PEX-2501000 37 1 Vibrating feeder JZ-3 5.5 1 Ball mill MQ18303600 135 1 Spiral classifier FG-1200 5.5 1 Mixing barrel 1500 3 1 1500 3 1 Flotation machine SF1.2X4 88 4 group SF0.62X4 24 2 group Belt conveyor Length according to the site conditions We can also supply other capacity copper ore beneficiation production line,according to users' needs. Welcome to consult us!

rake classifier

rake classifier

Let me describe a cycle of the Rake Classifier arm to you. The arm, with a series of rakes along its length, drops into the flow of slurry and is pulled upwards. Some of the fine material will flow over, the top of the rake. The rest will be pulled along with the coarser heavier material up the incline. When the arm reaches the end of its throw it will lift the rake out of slurry allowing the material to continue back flowing down towards the fine ore discharge. As the slurry begins to flow downwards, further classification takes place. Before the coarse material is able to travel out of range of the next rake on the arm it will be picked up again and pulled up the incline a bit further. The slurry will continue to be manipulated in this manner until all of the fine material has been washed out of it and the coarse is discharged at the other end of the Rake Classifier by its rakes.

The rake classifier (Figure 9.18(a)) uses rakes actuated by an eccentric motion, which causes them to dip into the settled material and to move it up the incline for a short distance. The rakes are then withdrawn, and return to the starting-point, where the cycle is repeated. The settled material is thus slowly moved up the incline to the discharge. In the duplex type, one set of rakes is moving up. while the other set returns; simplex and quadruplex machines are also made, in which there arc one or four raking assemblies, respectively.

The rake classifier such as the Dorr classifier consists of a rectangular tank with a sloping/inclined bottom. The tank is provided with movable rakes (reciprocating rakes). The feed in the form of a suspension (slurry) is introduced continuously near the middle of the tank. The lower end of the tank has a weir overflow (discharge weir) from which the fines that are not settled leave with the overflow liquid. The heavy material (coarser particles) sink to the bottom of the tank. The rakes scrap the settled solids upward along the bottom of the tank toward the top of the tank for discharge from a sand-discharge chute. The reciprocating rakes keep the slurry in continuous agitation. The time of raking stroke is so adjusted that fines do not have time to settle and so remain near the surface of the slurry, while the heavy particles have time to settle

Of the various classifiers employed in conjunction with ball and rod mills, the only ones at all widely used are those made under the Dorr-Oliver Companys patents. They can be divided intotwo classes, one consisting of the straight type and the other of the bowl type of classifier.

The machine consists of a settling tank in the form of an inclined trough with its upper end open, in which are suspended the rakes (3). The pulp to be classified enters the tank by the feed trough (1) ; the heavy material settles to the bottom, but any particles small enough to be discharged overflow the lip (2) in a continuous stream. The upper end of each rake is suspended by a link from a rocker arm (5) to which is attached a roller (6), the shaft supporting the rocker arm being fixed to the frame work that carries the driving mechanism. The roller (6) presses against the cam (7), which is keyed to the crankshaft (8) and revolves with it. The lower end of each rake is suspended by a link from a bell crank (10), the shaft of which passes through one end of a lifting lever (11), which in turn is carried on a framework fixed to the sides of the tank, but which remains stationary while the bell crank (10) is moving. Should the classifier be stopped and the tank become choked with sand, the rakes can be lifted clear by means of a worm gear (13) which raises the lifting lever (11) and so pulls up the whole assembly supporting the lower end of the rakes. The bell crank (10) is connected to the rocker arm (5) by a reach rod (12) ; each rake is also linked by a connecting rod (4) to a crank (9) which is cast in one piece with the cam (7).

The crankshaft is driven at a slow speed through a reducing gear. As it revolves the cranks (9) move the rakes backwards and forwards parallel to the bottom of the tank, but the cam (7) is so shaped that, when a rake is at the end of its strokes at the lower end of the tank, the rocker arm (5) and the bell crank (10) drop it so that it is just clear of the bottom. The crank (9) then pulls it up the tank by means of the connecting rod (4) to the full extent of its stroke, dragging up any sand that has settled to the bottom. At the end of this upward stroke the rake is raised by the cam through the rocker arm and bell crank so that, on the return stroke of the crank (9), it moves down clear of the sand which has been settling on the bottom of the tank. The downward stroke of the rakes gives the pulp a jigging motion which helps to keep the fine material in suspension, while the flow of the pulp from the ball mill produces a continuous overflow past the lip (2) which carries over any particles that are small enough to be discharged. The oversize sand, on the other hand, is dragged up the classifier by the rakes as fast as it settles and is finally discharged at the open end of the tank at the top of the slope in a comparatively dry condition.

Model D Classifiers are made in Simplex, Duplex, and Quadruplex typesthat is, with one, two, and four rows of rakes respectively. Simplexmachines are made in two sizes, 3 ft. and 4 ft. wide respectively, the corresponding Duplex classifiers being twice and the Quadruplex fourtimes as wide.

When a classifier is working in closed circuit with a ball or rod mill, it is usually possible to arrange their relative positions so that the discharge of the mill flows to the feed trough of the classifier while the oversize that is raked up the slope falls by gravity into the feed box of the mill; such an arrangement is shown in Fig. 9. The length of the classifier does not affect its operation and it can, therefore, be made of the exact length required to suit the mill.

The Model D Classifier has been superseded by Model F, which incorporates a new type of head-motion without a cam and with fewer moving parts. The Model D cam and roller type of head-motion restricts the speed at which the rakes can be run, since the roller bounces on the cam if the latter rotates too fast; the absence of a cam in the Model F mechanism makes a higher speed possible and gives the classifier a greater raking capacity in consequence. Model F Classifiers are being installed in most new installations in preference to Model D.

The operation of the mechanism can be seen from Fig. 19. The upper end of each of the rakes (1) is suspended by a rake hanger shaft(2) from a projection on the connecting rod (3). A crank (not shown in the diagram) connects shafts (4) and (5) and is keyed solid with shaft(5) , which is driven through a reducing gear as in Model D. As the crankshaft (5) rotates it moves the end (4) of the connecting rod (3) round in a circle as indicated by the dotted line ; the other end of the connecting rod is secured by a shaft (6) to the front link (7), the lower end of which pivots about a shaft fixed to a support on the tank. The position of the lower end of the link (7) being fixed, its upper end moves backwards and forwards in the path shown by the dotted line as the connecting rod oscillates. As the point (4) falls from (a) to (b) the point(6) rises from (a) to (b), and as the point (4) rises from (b) to (c) the point (6) falls from (b) to (c). The dimensions of the parts are so arranged that the movements of shafts (4) and (6) combine to give the required motion to shaft (2) carrying the rake, which is thus made to move up parallel with the bottom of the tank as the end of the crank moves from(a) through (b) to (c), but during the other half of its travel from (c) through (d) to (a) the reverse takes place ; both ends of the connecting rod rise as the crank moves from (c) to (d) and fall as it moves from (d)to (a) with the result that the rake is lifted and carried down clearof the sand ready foranother upward strokealong the bottom of thetank. The lower end ofeach rake is moved in asimilar way. It is suspended from a hangershaft which is supportedby the rear link (10) andthe bell crank (11) ; thelatter is pivoted on ashaft (12) held in placeby the lifting lever (13).A support fixed to thesides of the tank carriesthe whole lifting leverassembly, including aworm gear (not shown)which can be used toraise the bottom end ofthe rakes in case ofnecessity exactly as inthe Model D Classifier.The top end of the bellcrank (11) is connectedby a reach rod (14) toan eccentric (8), thecentre part of which is cast in one piece withthe crank.

The principle of themechanism is the sameas at the top end ; asthe rake is pulled up thetank, the rise of the bellcrank (11) compensatesfor the fall of the hangershaft (9), and vice versa,but, as it moves down,both bell crank andhanger shaft rise duringthe first half of the downward stroke and fallduring the second half,thus exactly duplicating the motion of the assembly supporting the topend of the rake.

Model F Classifiers are made in Simplex, Duplex, and Quadruplex types, their respective widths being the same as those of Model D. Table 14 can be taken as a basis of the overflow and raking capacity of Model F machines at different settings, although, on account of its smooth operation, the mechanism can be run at considerably higher speeds than those in the table, with corresponding increase in sand-raking capacity. The h.p. consumption is less than that of Model D owing to the reduction in the number of moving parts and the smooth positive operation of the mechanism.

The first two adjustments are fixed before the classifier is installed and they cannot be altered while the machine is running ; the controlling factors are so well known that it is seldom necessary to make a change after the machine has been erected.

The third adjustment is the method by which the operation of a classifier is controlled while the plant is running. The addition of water is always necessary because the ball mill discharge seldom contains less than 70% of solids while a classifier is never run with more than 50% of solids. The effect of the addition of water to a classifier is to determine the rate at which the solids will settle ; in a thick pulp they will settlemore slowly than a thin one. It follows that the coarser the overflow product required, the thicker should be the pulp, and vice versa. It must be understood that an increase in the volume of water, provided that the tonnage of solids remains the same, does not tend to carry coarser particles of ore past the overflow lip ; it has exactly the reverse effectit increases the settling rate and makes the overflow finer.

It will be seen from Table 14 that a separation finer than 100 mesh is likely to require a pulp in the classifier with less than 20% of solids. Since most flotation machines cannot be run economically with a pulp as thin as this, some means is needed of thickening it before flotation in installations where fine grinding is practised. A thickener can be used for the purpose, but the long contact period of the ore with water frequently results in over-conditioning of the pulp or undesirable oxidation of the mineral. The bowl classifier is designed to meet the difficulty and it is considered better to use it whenever possible in preference to a straight classifier followed by a thickener.

spiral classifier | henan deya machinery co., ltd

spiral classifier | henan deya machinery co., ltd

Spiral Classifiers is art of separating the solid particles in a mixture of solids and liquid into fractions according to particle size or density by methods other than screening. In general, the products resulting, a partially drained fraction containing the coarse material, called the underflow; and a fine fraction along with the remaining portion of the liquid medium called the overflow.

The classifying operation is carried out in a pool of fluid pulp confined in a tank arranged to allow the coarse solids to settle out, whereupon they are removed by gravity, mechanical means, or induced pressure. Underflow materials will be sent back to the ball mill for re-grinding to make a close-circuit, overflow materials will come to next stage of beneficiation.

Normally, there are two types of spiral classifier, high weir type and submersion type. High weir type, the overflow spiral blade is higher than overflow level, but spiral central is lower than overflow surface. The high weir spiral classifier is applied in the classification of minerals with particle size 0.83-0.15mm. Submersion type, spirals are totally under overflow level, which is applied with particle size 0.15 to 0.07mm.

classification - sciencedirect

classification - sciencedirect

Design features of the commonly used classifiers such as the spiral, rake, cone, bowl are described. Descriptions and design of centrifugal classifiers, such as the hydrocyclone, are given in some details. The mathematical aspects of designs that are related to operation of these classifiers and the theory behind the design and operation are discussed and explained in some detail. Mathematical correlation of variables that help to better understand the efficient operation of each process is derived and their use is explained using practical examples and solutions of common problems encountered in industry.

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