When the gangue content of lump coal is high, it is appropriate to use the jig or the moving screen jig for pre-discharging waste, and it is not possible to simply apply the direct separation process of three products.

When the amount of slime below 0.5mm is large, it is necessary to desliming in advance.

In the separation of free coal, the separation accuracy of jigging is no less than that of heavy medium separation, and the cost of jigging is lower than that of heavy medium separation.

When the discharge density is greater than 1.8kg/L, heavy suspension is difficult to achieve, and the advantage of single-stage jig is more prominent.

For individual coal preparation plants, the coal source is unstable, if the use of simple heavy medium separation is very likely to be due to the change of coal quality factors such as the amount of gangue and coal slime, it is difficult to ensure that the consumption of heavy media within a reasonable range, so that the production cost is high, not conducive to the improvement of economic benefits. In addition, if the coal washing plant adopts the pre-discharge or pre-desliming technology, the complexity of the system will be greatly increased, which is not conducive to the management and maintenance of the system, and the basic investment in equipment will be much larger.