Optimization of a Process Using Weak-Base Resin for the Recovery of Gold from Plant Solutions and Pulps

摘要

Laboratory testwork was carried out to provide additional information for a detailed cost-evaluation of a process using weak-base resin for the recovery of gold from pregnant solutions or pulps. A commercial weak-base resin maintains a satisfactory performance for at least 45 cycles of adsorption, elution (with sodium hydroxide), and regeneration (with sulphuric acid). This is equivalent to a period of 2 years' service in a production plant. It was established that silver, zinc, lead, and nickel can be satisfactorily eluted by the addition of free cyanide ions (added as sodium cyanide) to the caustic solution. Although the high consumption of cyanide (presumably due to its decomposition at the anodes of the gold electrowinning cell) makes this process far more expensive than caustic elution, the use of the eluant containing sodium hydroxide and cyanide may be justified in some circumstances, e.g., when the continuous elution of silver is required.