Mineral processing grading equipment classification effect

The classifier is an important part of the beneficiation . The new classifier is an important equipment of the classifier. It is mainly in three aspects, namely the ore properties (including the mud content and particle size composition of the classifier feed, the density and shape of the ore, etc. ); equipment structure (refers to the size of the dip angle of the trough, the height of the overflow weir and the new type of speed, etc.); the operation method (concentration of the slurry, the amount of ore and the uniformity of the ore)

1. The mud content and particle size composition of the grader feedstock

The more sludge or fine-grained grade in the grader feed, the greater the viscosity of the pulp, the smaller the sedimentation velocity of the ore in the pulp, and the coarser the size of the overflow product; in this case, to ensure The required overflow fineness can be appropriately increased to reduce the concentration of the slurry. If the amount of mud in the feed is small, or after de-sludge treatment, the slurry concentration should be appropriately increased to reduce the excessive fine-grained material in the return sand.

2. Ore density and particle shape

In the case of the same concentration and other conditions, the density of the material of the classifier is smaller, the viscosity of the ore slurry is larger, and the particle size of the overflow product becomes coarser. Conversely, the density of the material of the classifier is larger, the viscosity of the slurry is smaller, and the particle size of the overflow is larger. Thinning, the fine fraction content in the return sand increases. Therefore, when the grader has a high density of ore, the grader concentration should be appropriately increased; when the grader density is small, the grader concentration should be appropriately reduced. Since the flat ore is slower than the round or near-round ore, the classifier should use a lower slurry concentration or speed up the discharge of the overflow product.

3, the inclination of the classifier machine slot

The inclination of the trough not only determines the settlement area of ​​the classifier, but also affects the degree of agitation of the new type of pulp to the slurry, thus affecting the quality of the overflow product. The inclination angle of the trough is small, the sedimentation area of ​​the classifier is large, the overflow particle size is fine, and the fine grain content in the reclaimed sand increases. Conversely, the dip angle of the trough increases, the settlement area decreases, and the coarse grain material has more chance of falling, and the overflow granularity Thicker, but less sand back. Of course, after the classifier is installed, its inclination angle is not changed, and it can only adapt to the predetermined inclination angle under the operating conditions.

4, the level of overflow weir

Adjust the height of the weir to change the size of the settlement area. When the weir is increased, the sedimentation area of ​​the ore particles is increased, and the volume of the classifier is also increased. Therefore, the new agitation of the slurry surface is relatively weak, and the overflow particle size is made fine. When the overflow particle size is required to be coarse, the height of the weir should be reduced.

5, the new speed

The new rotational speed not only affects the particle size of the overflow product, but also the ability to transport the grit. Therefore, when selecting a new type of speed, it is necessary to meet both the overflow fineness and the returning sand productivity. The faster the speed, the higher the production capacity according to the sand return meter, but the agglomeration effect on the slurry becomes stronger, and the coarse particles entrained in the overflow increase, which is suitable for the classifier used in the rough grinding cycle. The classifier used in the second stage of grinding or fine grinding cycle requires a finer overflow product, and the new speed should be slowed down as much as possible.

6, pulp concentration

Slurry concentration is one of the most important adjustment factors in classifier operation, and it is usually used in production to control the classifier's overflow fineness. In general, the slurry concentration is low, the overflow particle size is fine, the concentration is increased, and the overflow particle size becomes coarse. This is because in the thicker slurry, the viscosity of the slurry is larger, the interference of the particle sedimentation is large, and the sedimentation speed is slow. Some of the coarser ore particles are too late to sink, and the horizontally flowing pulp is brought out of the overflow weir. The overflow particle size is made thicker. However, when the slurry concentration is very low, there may be cases where the overflow particle size becomes coarse. This is because the concentration is too low. In order to maintain a certain production capacity based on solid mass, the amount of slurry is inevitably large, causing the slurry flow rate in the classifier to increase, thereby rushing the coarser ore. Going in the stream. Therefore, in actual production, for the classifier machine that processes the specified ore, there is a suitable classifier slurry concentration. At this suitable concentration, the maximum production can be obtained while maintaining a certain classifier particle size; while maintaining a certain productivity, the smallest separation particle size can be obtained. This concentration is called the critical concentration. The critical density of the actual production should be determined by testing and referring to the indicators of similar classifier operation.

7. Uniformity of ore and ore supply

When the concentration of the slurry is constant, if the amount of ore fed to the classifier is increased, the ascending flow rate and the horizontal flow rate of the slurry are also increased, thereby making the overflow particle size coarse. On the contrary, when the amount of ore is reduced, the overflow particle size becomes finer, and the fine particle content in the returning sand increases. Therefore, the ore-feeding amount of the classifier should be appropriate, and it should be kept even and stable, so that the classifier process can be carried out normally and a good classifier effect can be obtained.

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