Ball size distribution for the maximum production of a narrowly-sized mill product

•Milling circuit and ball size distribution models determined the make-up ball charge.•Investigations focused on mono and binary mixture of ball sizes for make-up charge.•The results found reccommended charging mono-sized balls in the make-up charge.•Optimal conditions for the size and composition of make-up charge were determined.•The conditions enable maximum production of the desired size range for flotation.

Ball size distribution is commonly used to optimise and control the quality of the mill product. A simulation model combining milling circuit and ball size distribution was used to determine the best make-up ball charge. The objective function was to find the ball mix that guarantees maximum production of the floatable size range (i.e. − 75 + 9 μm) applicable to a platinum-bearing ore.The simulated product size distributions were found to display a close match with the measured product from an operational mill. Based on the maximum production of floatable particles, the best combination of make-up ball size was determined in relation to feed flow rate, feed size distribution and ball filling.

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