Gravel mill load control

The gravel mill is in the second stage of closed-circuit grinding, and the ore is the underflow (return sand) and gravel of the cyclone. The underflow is constrained by the first stage of grinding, and the adjustment of the first stage of grinding to change the ore supply of the gravel mill is too long and is affected by many factors. By changing the amount of gravel added, the load of the gravel mill can be changed more quickly, and the load control or extreme value control of the gravel mill can be realized, and the entire grinding system can be stabilized under the condition that the concentration of the donor is constant. It also has a significant impact on the grinding efficiency of the gravel mill.

There is a single peak characteristic relationship between the gravel mill load (load) and its actual motor power value. As the load gradually increases, the power increases as it reaches a maximum value and then begins to fall. At the maximum value of power consumption, the grinding rate is the highest, so the system is required to have an extreme value control function, or to control the rising section to the left of the maximum value of the curve to be close to the maximum value. The control system is required to make a logical judgment on the left or right side of the maximum value of the load-power curve of the operating point. The gravel mill load control system is shown in Figure 1. The latter is often used in actual use. When the power of the gravel mill motor is less than a certain set value (90%), if the operating point is to the left of the maximum value, the power relay turns on the gravel feed belt and adds gravel to the gravel mill. When the motor power reaches a maximum (100%), the power relay disconnects the gravel to the motor of the ore belt and stops the gravel addition. Repeat this way. Realize the fixed value control of the grinder.

Figure 1 Gravel mill fixed value mine control