Smelting of Miller chlorides with sodium silicate and oxygen refining of the silver-copper alloy

摘要

A mixture of copper chloride and silver chloride,which is known as Miller chloride, is produced during therefining of molten gold with gaseous chlorine. In the presentwork, the mixed chloride was reduced with sodium silicate andcharcoal according to the following reactions:2AgCl + Na_2O.SiO_2 + C = 2Ag + 2NaCl + SiO_2 + CO_2 + 1/2O_22CuCl + NA_2O.SiO_2 + 2C = 2Cu + 2NaCl + SiO_2 + CO_2 + COThe effects of sodium silicate, borax and charcoal additions andsmelting temperature on the metal recovery and quality weredetermined. After smelting, the silver-copper alloy was refinedwith oxygen under the silicate-based slag. Sodium silicateadditions of about twice the stoichiometric requirement andborax additions of about ten mass percent were necessary toachieve the maximum silver recovery. The silver recoveryincreased with operating temperature and the results showed thatninety-five percent of the copper could be removed with a silverrecovery of almost ninety percent. The silver losses to the slagand the salt increased as the copper was removed. A mechanism,which involved the formation of some silver oxide, wasemployed to explain the loss of silver to the slag.