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Question A concentrator plant treats 6,500 tonnes per day of a clayey copper and gold ore containing 3.7% moisture and average feed grade 0.50% Cu and 56 ppm (parts per million) Au. Normal average recoveries to Smelter Concentrate at the concentrator are; 92% Cu and 86% Au. However, a change in ore hardness over ten continuous days led to coarser grind and consequently, a drop in recovery to 88.3% Cu and 81.0% Au. Calculate: a) The average mass of Au in Kg contained in the ore per day. b) The total loss in revenue over the ten days attributed to Cu and Au metals. Assumptions: Combined Smelter and Refinery recoveries of Cu = 96.5% Conversion of Au in concentrate to metal = 89.3% Price of Cu metals = USD 8,755/t Price of Au = USD 18.50/ounce