Two chlorination processes are shown here, both involving prior roasting of gold-bearing mineral concentrate derived from crushed ore. On the left, the earlier process involved generating chlorine gas, and passing it through the roasted concentrate in a sealed vat. A soluble gold chloride was formed, which was dissolved by flushing the vat with water (lixiviation) - the gold was then precipitated in a lead-lined vat, using iron sulphate. The later wet-process (right) mixed water, sulphuric acid and bleach with the sands, in a revolving barrel.
Created: 9 March 2006, Last modified: 2 June 2006