Question 4 The process route selected for the cyanide leaching of gold is dependant among other things on whether the gold ore is free milling or refractory. i) Explain why cyanide leaching of gold is done at alkaline pH? ii) Indicate two different categories of gold refractoriness and briefly suggest pre-treatment methods used for each before the cyanidation process. iii) Choose one of the indicated class of refractoriness indicated in (ii) above, draw an annotated flow diagram to indicate a possible hydrometallurgical route in the processing of gold from a high grade refractory ore Question 5