The recovery of gold cyanide by acetylene black

Abstract

For many years acetylene black (ACB) has been used in dry cell batteries to lower the electrical resistance of the cell. Recently, ACB has been investigated as a possible adsorbent for cyanide complexes owing to its dual structure and relatively small surface area. Results obtained showed that the adsorption of gold from cyanide solutions onto ACB is far more rapid than any other process currently used in the mining industry. ACB kinetically outperformed adsorbents such as activated carbon and ion exchange resins. However, its gold loading capacity was far less than that of activated carbon or ion exchange resin. The equilibrium loading of gold onto ACB was reached in a few minutes due to its small surface area. Adsorption profiles indicated that intraparticle diffusion could be ignored when gold is adsorbed onto A CB, and a mechanism of surface adsorption was postulated. X-ray diffractrometry indicates that ACB is partly graphitic and partly amorphous, but due to the minimal intraparticle diffusion one can however expect the graphitic fraction to be small relative to the amorphous fraction. While pH and the addition of strong oxidizing agents influence the adsorption profile of gold cyanide onto ACB, the effect of oxygen enrichment was minimal.