Pre-screening

Pre-classification is generally not used before the first stage of grinding. It is only considered when the feed particle size is less than 6-8mm and the content of qualified products in the feed is greater than 15%. The main function of pre-classification in the process is to pre-separate the qualified products of the ore type in order to increase the processing capacity of the mill, or to separate out the secondary sludge for the next step.

Full closed circuit grinding inspection and classification

The function of the fully closed-circuit grinding inspection and classification is to control the particle size of the grinding products. The classification returns to the mill, which increases the ore throughput per unit time of the mill and improves the production capacity of the mill. However, the cyclic load of returning sand will affect the production capacity of the mill.

The inspection and classification in the first-stage grinding and the second-stage grinding can make the grinding machine work effectively, avoid over-grinding and meet the grinding fineness requirements of the next-stage beneficiation operation. Therefore, it is always necessary to check grading assignments.

overflow control classification

In the first stage of grinding, a very fine end product must be obtained, or when stage separation is required in the first stage of grinding, or when a hydrocyclone is to be classified, the over-coarse must first be removed in a mechanical classifier When granulating, the overflow control classification operation is adopted.

Sand return control classification

The purpose of sand return control and classification is to reduce the content of qualified products in the sand return, although the effect is not very significant, and it is necessary to add a classifier to increase the complexity of the configuration, but it is still used in practice.

Partial closed circuit grinding inspection and classification

Partial closed-circuit grinding inspection and classification is not only the inspection and classification of the first stage of grinding, but also the pre-classification of the second stage of grinding. The main feature of this grading process is that the change of the second stage mill load is not through overflow, but through sand settling, so the load between the two stage mills is easy to distribute and adjust. However, this classification process also has drawbacks. One stage of classification removes a large amount of ore slime, which greatly reduces the amount of ore slime in the second stage of classification, reduces the viscosity of the pulp, and makes the classifier work unstable.

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