Question1:

A milling circuit consists of a rod mill followed by a ball mill. The 80% passing feed and product sizes of the SAG mill are 15cm and 1mm respectively. The final product 80% passing size from the ball mill is 100m. The total specific energy input for the two milling stages was 13.6kWh1. Circuit feed samples taken at the same time were sent for Bond work index testing. The rod mill test gave RWilab of 13.5kWht1 and a ball mill work index BWilab of 12.6kWht1. Calculate: (1) The operating work index of the circuit. (2) The standard Bond energy for the circuit. (3) The relative efficiency of the circuit