The behaviour of gold bearing minerals during froth flotation as determined by diagnostic leaching

The aim of the present paper is to explain the recovery of gold by flotation as a function of the floatability of liberated and precipitated gold and gold occluded in base metals sulphides, pyrrhotite, pyrite, and arsenopyrite. In contrast with many other studies, the current research determines the flotation recovery of each mineral as an integral part of the ore. A further feature of this study is the fact that a significant fraction of the gold is associated with pyrrhotite, so that flotation strategies are aimed at maximising the recovery of pyrrhotite, which is in contrast with the practice in many similar flotation processes. Quantitative XRD and diagnostic leaching are used to determine the distribution of gold between the host minerals as well as the flotation recovery of each mineral. Optimal sulphide recovery is attained by activation with copper sulphate, conditioning with potassium amyl xanthate and nitrogen, and flotation with air. The greatest recoveries of free gold occurred when oxygen was added during xanthate conditioning. The recovery of gold bearing sulphides, free gold and refractory gold will be discussed for each test where oxygen and nitrogen addition to the pulp was used.