Gold recovery from carbon-in-pulp eluates by precipitation with a mineral acid I. Precipitation of gold in eluates contaminated with base metals

Abstract

This paper is the first in a series of three to describe a process for gold recovery from carbon-in-pulp (CIP) eluates, containing gold but contaminated with base metals. Recovery of virtually all the gold is effected by either hydrochloric or sulphuric acidification of the eluate. In this paper the effect of pH and temperature on the gold precipitation step is described. An attempt is also made to elucidate the chemical nature of the precipitate using X-ray techniques. In a second paper, the production of gold bullion from the precipitate is described. Treatment of barren solution from the precipitation step to recover residual gold values, the settling rate of the precipitate and precipitation of the gold from a recalcitrant eluate, low in base metals by the addition of CuSO 4·5H 2O will also be discussed. In a final paper, a material balance is proposed for a batch plant to produce a nominal 100 kg of gold from real plant eluate using the precipitation route. Precipitation is compared with electrowinning where it is shown to have certain advantages for specific eluates.