Stone gold recovery/hard rock gold process/how to gold stone

Stone gold recovery/hard rock gold process/how to gold stone
Free gold When it is not included in other minerals, gold is particularly easy to extract, by simple gravimetric separation, amalgamation or direct cyanidation. Gold associated with iron sulphides Disseminated in the form of very fine particles in crystals of pyrite or pyrrothine, its extraction requires an already more complex process, generally comprising preconcentration and calcination of the concentrates, followed by cyanidation. Gold associated with arsenic or antimony ores The presence of these elements makes treatment even more difficult and the conventional process (concentration, calcination, cyanidation) can lead to extraction yields that are too low to allow economic exploitation. Gold associated with copper, lead or zinc ores These ores are mentioned here only for the record, gold being a by-product, sometimes very important, of other metals. Porphyritic copper ores, extracted on a very large scale, lead to substantial gold production. In copper metallurgy, gold follows copper to electrolytic refining, where it is recovered from electrolysis sludge. Nature of deposits A distinction is made between primary deposits, of preorogenic volcano-sedimentary and postorogenic plutono-volcanic types, and secondary deposits of detrital types.