Development of the process of Resin Gold Extraction

R esins can give higher loading capacity and also a better kinetic than activated carbon, especially in solutions where the concentration of competing ions is low. Also resins don’t experiment problems in the treatment of clayey ores or when the presence of fine particles is usually a problem. However, activated carbon is affected by that kind of ores because its pores can be blocked easily and consequently the efficiency is low.

Other advantage that resins offer is the possibility of work in temperatures where activated carbon could be inefficient. Organic material affects activated carbon but no resins. Also organic reagents such as kerosene and flotation reagents are not interference to loading capacity of resins. It’s to be expected that the greatest difficulties will be appear when the process is applied to the cyanidation of auriferous concentrates obtained by flotation, since these have a high content of sulphides of heavy metals which form complex cyanides that can be absorbed onto the resin. Conversely, one of the most favorable cases arises when the process is applied to the cyanidation of auriferous tailings, as the tenor of sulphide and accompanying metals is very low.

There several ways of apply ion exchange resins in the treatment of auriferous ores: to solutions and pulps, but the most known process is the resin-in-pulp (RIP). In this process, the adsorption is done in the same pulp with solid-liquid separation. The absence of separation phases offer economic advantages, but its application is conditioned to the existence of resins with good strength.

The economy of the process is influenced by the fact that some amount of resin can be lost after being in a heavy pulp under agitation; although the losses are minimized considering that the pulp is moving in countercurrent. Other favorable aspect is in the possibility of absorb almost all the gold leached without employing solid-liquid steps (i.e. use thickeners or filters).

Applying the countercurrent principle for saturation of the resin, and a different retention time in each stage for the resin and for the pulp is favorable to the adsorption of gold. Elution could be carried out in a counter current way, obtaining a satisfactory gold content in the eluate.