OCR Text |
Show How Gold Is Refined Placer gold deposits are worked by washing the gravel to remove the greater part of the lighter barren bar-ren rock, followed by treatment of the concentrate by the cyanide process. proc-ess. Sodium cyanide is used to dissolve dis-solve the gold; the clear solution is drawn off into another vessel where the gold is precipitated by adding zinc. In the chiorination process, the gold-beailng quartz is treated with chlorine, producing gold chlorine chlo-rine which dissolves. From the clear solution the gold is precipitated by adding ferrous sulphate solution. The gold bullion obtained by either process contains traces of silver, copper, iron and other metals. These are separated by treatment with sulphuric sul-phuric acid and by an ebrctxolytic process. |