Coarse grinding versus fine grinding in gold recovery by cyanidation.

The commercial application of the solubility of gold in cyanide solution, had its inception in the McArthur-Furrest patent of 1887 [...] Since then the process has spread to every gold and silver mining disrict in the world, with few exceptions, and although not equally successful with every class of ore, it may fairly be claimed that its introduction has revolutionized the metallurgy of the precious metals. Agitation of the ore with cyanide solution was an integral part of the first tests of the feasibillity of the new process; but in commercial application, cyanidation developed into the leaching process, because of the lack of equipment to affect the agitation and filtration. Also grinding was not carried to a point of great fineness and neither was it necessary in view of the fact that most of the pre treated came from the oxidized zone, where the gold was largely "free", and comparatively coarse. [...