Abstract
Mineral processing of refractory gold ore is uneconomical through conventional processing methods. The ore recovery is normally below 80% due to sulphide encapsulated gold and result into high reagent consumption by carbonates. This study was conducted to investigate the use of ozone to the existing pre-treatment processes to increase the gold recoveries. To achieve this, ozone gas was bubbled in slurry at different pH values to establish the optimal pH. The resulting residue was subjected to cyanidation and Resin in Pulp (RIL) leaching to assess the effect of ozonation on gold leaching and reagent consumption. The results obtained showed that ozonation at pH 2 for 4 hours increased gold recoveries from 10% to 70%. Base metals such as arsenic, zinc and manganese were found to leach during ozonation with a recovery of 37%, 32% and 51% respectively. Ozonation improved recoveries from refractory ores with minimal cyanide and lime consumption and can prevent preg-robbing.