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Abstract
At the Sarcheshmeh copper mine, 41 000 t ore per day with an average grade of 0.9%Cu is ground to 70% passing 75 µm. Grinding is effected in eight parallel lines of 8 x 5 m ball mills in a closed circuit with cyclones. The makeup balls are 80 mm forged alloy steel balls and the average ball consumption is 750 g/t ore ground. In order to optimize ball size distribution inside the mill, based on the previous investigation, instead of using only 80 mm makeup balls, a combination of 80 and 60 mm (75 and 25 wt-%) ball charge was used in one of the grinding lines. To evaluate the performance of three ball types, namely, forged alloy steel balls (A), ductile cast iron (C), high chromium cast iron (D) and also a combined (80 and 60 mm) charge of forged alloy steel balls (B), four identical parallel mills were charged accordingly. These four mills were sampled during a period of 1 year. The amount of material finer than 75 µm cyclone overflows was selected as a criterion for the performance evaluation. It was observed that in a mill with the combined makeup balls, the amount of fines (<75 µm) produced was 4% higher than that of the other mills. The consumption of ball types A, C and D were 730, 710 and 534 g/t respectively. The results of laboratory flotation tests showed that owing to an improvement in the production of fines, an increase of 1.4% in the overall copper recovery is obtainable. Owing to the promising results, the new makeup ball regime was implemented in all mills in the plant.

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	All Years to Access Full-Text Export citations Effect of ball size on the performance of grinding and flotation circuits: the Sarcheshmeh copper mine case By S. Banisi and M. Farzaneh Published in Mineral Processing and Extractive Metallurgy (MPEM) at 2006 Direct link: http://kmpchemmat.ir/pii/35320 Abstract At the Sarcheshmeh copper mine, 41 000 t ore per day with an average grade of 0.9%Cu is ground to 70% passing 75 µm. Grinding is effected in eight parallel lines of 8 x 5 m ball mills in a closed circuit with cyclones. The makeup balls are 80 mm forged alloy steel balls and the average ball consumption is 750 g/t ore ground. In order to optimize ball size distribution inside the mill, based on the previous investigation, instead of using only 80 mm makeup balls, a combination of 80 and 60 mm (75 and 25 wt-%) ball charge was used in one of the grinding lines. To evaluate the performance of three ball types, namely, forged alloy steel balls (A), ductile cast iron (C), high chromium cast iron (D) and also a combined (80 and 60 mm) charge of forged alloy steel balls (B), four identical parallel mills were charged accordingly. These four mills were sampled during a period of 1 year. The amount of material finer than 75 µm cyclone overflows was selected as a criterion for the performance evaluation. It was observed that in a mill with the combined makeup balls, the amount of fines (<75 µm) produced was 4% higher than that of the other mills. The consumption of ball types A, C and D were 730, 710 and 534 g/t respectively. The results of laboratory flotation tests showed that owing to an improvement in the production of fines, an increase of 1.4% in the overall copper recovery is obtainable. Owing to the promising results, the new makeup ball regime was implemented in all mills in the plant.