Adjustment and control of grinding concentration and product fineness in mine beneficiation ?
Grinding quality fraction (grinding concentration) refers to the mineral pulp quality fraction in the grinding machine. The grinding product fineness refers to the content of the specified grade in the discharge of the grinding machine. The grinding concentration and grinding product fineness are interrelated and affect each other. In the production operation, it is mainly controlled by the adjustment of the ore water (backwater).
First, the factors that affect the grinding concentration are ore properties (mainly particle size composition), ore feed quantity and ore feed water. The factors affecting the fineness of grinding products include raw ore size composition, grinding concentration and ball loading system.
For example, when the nature of raw ore changes, such as increase of coarse particles, but the feed quantity is not changed, the backwater should be reduced and the grinding mass fraction should be increased to ensure the grinding fineness; if the backwater is increased, the backwater should be increased and the feed quantity should be increased to reduce the over-grinding.
Under the condition of keeping the mineral property and medium condition unchanged, the general grinding fineness increases with the increase of the grinding concentration, while the other is less fine. In short, by adjusting the feed water to adjust the grinding concentration, thereby controlling the grinding fineness.
Second, the closed-circuit grinding, due to the increase of a return sand amount of factors, the situation becomes more complex. When feedwater is constant, the increase of feed ore and return sand will increase the grinding concentration, otherwise, it will decrease. The fineness of grinding is affected not only by return sand but also by classification efficiency. When the sand quantity is large, the total grain size composition is changed, the fine grain size is increased, the grinding speed is fast, the quality fraction of the grinding ore should be reduced appropriately, and the ore discharge speed should be increased in order to reduce the crushing. When the amount of returned sand is reduced and the raw ore is coarse, the backwater should be reduced to improve the grinding quality.