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Abstract
The population balance method was used to model the grinding at the Sarcheshmeh copper mine which processes 40,000 t/d of ore at 0.8% Cu. In this plant, grinding is carried out by 8 parallel ball mills (8 m x 5 m) working in closed circuit with cyclones. The ore with a F80 of 12.7 mm is ground to 70% passing 75 microns to be fed to the flotation circuit. The modified Herbst and Fuerstenau's method was used to determine the breakage function of the ore. Due to variation of the grindability of the ore, the breakage function of various ore type was obtained. It was observed that the breakage function of the ore was normalizable. Using plant data, the selection function of the ore was calculated through a software package which was written for this propose. The software was then used to predict the size distribution of the discharge of the ball mill for various feedrates. To verify the results, the simulated and actual size distributions of the discharge of the mill was compared. A reasonable agreement was observed ( (15 % relative error). In order to examine the effect of internal classification in the mill, a pilot scale mill (1.6 m x 1.3 m) with a feedrate of 1.6 t/h was stopped and completely emptied. The collected material (600 kg) was dried, sampled and size analyzed. It was observed that amount of material between 100 to 325 mesh inside the mill was significantly higher than that of the feed. For instance, the percent retained on 200 mesh screen in the feed and inside the mill was 4.49 and 8.51, respectively. When the internal classification effect was incorporated in the simulation of the plant data, the accuracy of the results were significantly improved.

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	All Years to Access Full-Text Export citations Effect of internal classification on modelling ball milling at the Sarceshmeh copper mine By S. Banisi, S. Zyed-Abadi and G. Langari-Zadeh Published in Comminution '98, Brisbane, Australia, Feb. 16-18 at 1998 Direct link: http://kmpchemmat.ir/pii/25262 Abstract The population balance method was used to model the grinding at the Sarcheshmeh copper mine which processes 40,000 t/d of ore at 0.8% Cu. In this plant, grinding is carried out by 8 parallel ball mills (8 m x 5 m) working in closed circuit with cyclones. The ore with a F80 of 12.7 mm is ground to 70% passing 75 microns to be fed to the flotation circuit. The modified Herbst and Fuerstenau's method was used to determine the breakage function of the ore. Due to variation of the grindability of the ore, the breakage function of various ore type was obtained. It was observed that the breakage function of the ore was normalizable. Using plant data, the selection function of the ore was calculated through a software package which was written for this propose. The software was then used to predict the size distribution of the discharge of the ball mill for various feedrates. To verify the results, the simulated and actual size distributions of the discharge of the mill was compared. A reasonable agreement was observed ( (15 % relative error). In order to examine the effect of internal classification in the mill, a pilot scale mill (1.6 m x 1.3 m) with a feedrate of 1.6 t/h was stopped and completely emptied. The collected material (600 kg) was dried, sampled and size analyzed. It was observed that amount of material between 100 to 325 mesh inside the mill was significantly higher than that of the feed. For instance, the percent retained on 200 mesh screen in the feed and inside the mill was 4.49 and 8.51, respectively. When the internal classification effect was incorporated in the simulation of the plant data, the accuracy of the results were significantly improved.