| 摘要 |
<p>Char containing adsorbed gold and/or silver values, as obtained from cyanide pulp, is contacted with a water-ammonia solution containing more than 28 per cent by weight ammonia, and the solution containing the desorbed metals is separated from the char, which after washing is suitable for re-use. Ammonia gas is introduced into the treatment chamber containing the char and water or weak ammonia solution until a pressure of 80-120 p.s.i. absolute or more is attained and maintained at a temperature of 40-90 DEG F. When desorption is complete, ammonia is recovered by boiling and release of pressure, and the char separated from the liquid containing gold and silver ammines. The metals are precipitated from the solution by zinc or aluminium powder, and an activator consisting of sodium or potassium cyanide, or caustic soda respectively. If the char is magnetic, it may be separated magnetically from the liquid instead of by filtering or screening.</p> |
