AN INVESTIGATION INTO ALTERNATIVE ELUANTS FROM ACTIVATED CARBON AT ATMOSPHERIC-PRESSURE

One of the slowest steps in the extraction of gold by CIP/CIL techniqu es is the desorption of the metal from the loaded activated carbon. Th is paper seeks to examine ways of improving the kinetics of this desor ption in an economic way through the use of organic additives to the t raditional NaCl - NaOH elution solutions. Several organic agents such as propylene glycol, ethanolamine, urea, N,N-dimethylformamids, aceton itrile and ethanol were trialed. This was done in laboratory bench sca le tests, and tests also carried out using an electrowinning cell in t andem with the elution column. Comparisons are made with previous work and results compared with the Zadra elution system which serves as a benchmark. It is shown that a solution of 3.0% w/w thiourea, 2.0% w/w NaOH, and 0.05% w/w NaCN represents the best prospects for greatly imp roved throughput in industrial cells. A subsequent paper will report p ilot and commercial scale tests. The procedure is now standard alterna tive practice at the gold heap leaching complex of Perseverance Explor ation in Fosterville. (C) 1997 Elsevier Science Ltd.