Three principles for ball mill operation

The ball mill can be said to be the core equipment of a concentrator, which is equivalent to a person's heart. Only the normal operation of the ball mill can ensure the smooth progress of each subsequent beneficiation step. Here, we summarize the three major criteria for the operation of ball mills, namely "uniform ore feeding, large sand return, and high concentration". Following these three guidelines to properly operate a ball mill can help extend the life of the ball mill and improve grinding efficiency.

Criterion 1: Equal feeding

One of the guidelines for the proper operation of a ball mill is to evenly feed the ore. So, what is "equalization"? In fact, the "equal feeding" here contains two meanings: one is to ensure that the feeding particle size is uniform; The second is to ensure that the ore feeding speed (the amount of ore sent to the grinding equipment per unit time) is constant.

Once the ore feed is uneven, blindly increasing the ore feed may lead to the coarse particle size of the grinding product and the increase of the sand return. In this case, it is very likely to cause the "bloating" phenomenon of the ball mill, and even lead to a decrease in output (the sudden decline in the output of the beneficiation ball mill is the reason for this).

If the ore feed is insufficient, the discharge particle size of the grinding equipment will be finer, and the amount of sand return will be reduced accordingly. When the feed amount remains the same, the increase or decrease of the feed particle size will be similar to the above-mentioned situation.

Therefore, the ore feed amount and ore feed particle size should be continuous, uniform and stable at a high level, and the frequent fluctuations of more and less will inevitably affect the grinding effect.

Criterion 2: Large return to sand

Sand return refers to the coarse-grained particles that are returned to the grinding equipment by the grading equipment for re-grinding during closed-circuit grinding. Usually, the amount of ore returned is often several times more than the original ore supply, and we call the ratio between the amount of sand returned to the amount of raw ore called the return sand ratio. The "large sand return" mentioned here requires us to maintain an "ideal sand return ratio" during the operation of the grinding equipment.

It has been proved that the size of the sand return ratio will directly affect the production efficiency of grinding equipment. When the return of sand is large, the increase of the total ore feed of the grinding equipment accelerates the discharge speed of the grinding equipment, shortens the residence time of the ore in the cylinder, and accelerates the circulation. It is found that within a certain range (such as between 100% —— 500%), with the increase of the sand return ratio, the productivity of the grinding equipment will also increase, and when a certain value is reached, the productivity increase gradually becomes smaller, and the full feeding of the grinding equipment is close to its upper limit of passing capacity. Therefore, the return ratio should be stable and close to a certain constant value, which results in an ideal productivity and at the same time reduces energy consumption.

Criterion 3: High concentration

The so-called "high concentration" refers to the high percentage of the ore weight in the total slurry weight. The magnitude of the grinding concentration determines the friction between the grinding medium and the material.

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