Exploration And Practice Of Optimum Filling Rate Of Large Ball Mill

With the reduce ore grade and increase the price of various energy sources, using efficient and low-cost large-scale ball mill has become the main trend of modern concentrator construction. But the grinding efficiency of large-scale ball mill is lower and can expend large amount of consumption of energy. The large-scale ball mill’s grinding function is accomplishing by grinding medium, the grinding medium filling ratio become the key factor of grinding result. Therefore, it is significant for improving the grinding efficiency of large-scale ball mill and reducing energy consumption to optimize grinding medium filling ratio.The paper mainly aims at the best filling ratio of the first concentrator of Jinchuan Group Ltd MQY D×L5.5×8.5m large-scale ball mill to conduct research. The research first analyzed the influence of the grinding medium for the grinding process, under the condition of low rotate speed, only by reducing filling ratio to make grinding medium be in a reasonable state of motion in ball mill. In addition, the grinding medium filling ratio also directly determined the available power of large-scale ball mill, so the paper mainly by optimizing grinding medium filling ratio to increase grinding efficiency. The existing grinding theory is based on Davis Leivn Nicholson’s steel ball movement theory, but the large-scale ball mill filling ratio in production is30～35%and does not meet the prerequisites, the large-scale ball mill’s best filling ratio can’t quantitative calculated. So optimization for large-scale ball mill’s best filling ratio is final determined by probe test.The ore’s mechanical property of the first concentrator of Jinchuan Group Ltd is unevenly, the last date of mechanical property indicates that the mine exist no less than30%high tenacity ores, The ore’s mechanical property unevenly and the high tenacity ores make the grinding product exist reasonable quality questions, it direct influence the beneficiation indexes, and make the MgO content in the Nickel concentrate higher, also increase the consumption of steel and energy. Conducting the high tenacity ores not only need enough impact force but also need intensify grinding medium abrasive action. In addition, the first concentrator of Jinchuan Group Ltd have lack adequate awareness of the first use MQY D×L5.5×8.5m large-scale overflow ball mill’s performance, especially lacks the matured experience for the grinding medium system of large-scale ball mill. The filling ratio of every grinding stage is35～37%at present, the bad grain size composition of grinding products is closely related to the high filling ratio, only reducing the large-scale ball mill’s filling ratio to ensure the grinding medium keep a good state of motion.The filling ratio test in lab results show the filling ratio has little influence on the grinding effect, the main reason is the small ball mill in lab is discontinuous grinding, the grinding time is short and with few feeding capacity, so it difficult to correspond the production simulation results of the scene large-scale ball mill. The best filling ratio still need to adjust in actual production.Before the industrial test start, the grinding medium filling ratio exploratory experiment propose a new determine the large-scale ball mill’s best filling ratio method, by means of monitor the grinding fineness and the beneficiation indexes to find the best filling ratio of the large-scale ball mill, and then continue to use this method in the industrial test. During seven months industrial test, every stage grinding ball mill’s filling ratio reduced5-6percentage points, the first stage once grinding reduced to30～31%, the first stage twice grinding and the second stage grinding reduced to31～32%. With the filling ratio reduced, the grain size composition of the grinding product tend to be more reasonable, the easy selection fraction increased by a large margin the beneficiation indexes comprehensive improvement:the recovery of nickel improve2.13percent, the recovery of copper improve3.76percent, the nickel concentrate grade improve2.13percent, copper concentrate grade improve0.19percent, the MgO content in concentrate reduce0.6percent. At the same time, the grinding power consumption reduce5.13percent and reach the anticipated result.