The potential of Sudanese Refractory Gold Ores Characterization and Pre-treatment in Ariab Mines (VMS) in Red Sea (Sudan)

Abstract

This laboratory work demonstrates the ability to characterize and pre-treat Sudanese refractory gold ores at Ariab mines to extract the gold with optimal parameters. Characterization studies were performed by AAS, XRF and XRD analysis to assess the abundance of elements and mineral phases. In addition, the acidity of the ore was examined to estimate the effective amount of lime. The ore was subjected directly to cyanidation without any pre-treatment. High oxidation reagent processes were carried out to pre-treat the ore. Chemical analysis results show the gold grade to be 1.37 g/t. In addition, the ore contained 51.78% Fe2O3, 43.40% SO3, 2.39% CuO, 1.47% SiO2, 0.35% Cr2O3, 0.17% CaO, 0.08% As2O3, 0.06% ZnO and 0.06% MnO. The XRD result shows that the ore phases are Pyrite (FeS2), Chatkaite (Cu6Fe+2Sn2S2) and Quartz (SiO2). The investigations of direct cyanidation elucidated that the ore can consume a high amount of cyanide with unsatisfactory recoveries for gold (Exgold ≤39.41%). The influence of the cyanide concentration, pulp density (% by weight), leaching time hr, agitator speed and pH were examined in direct cyanidation experiments. In pre-treatment experiments, the effect of hydrogen peroxide (H2O2) and concentrations on gold recovery was studied. The pre-treatment of the ore with H2O2 achieved a good impact on the gold extraction performance. The higher gold extraction was obtained at hydrogen peroxide (H2O2) 300 ppm, cyanide concentration 3500 ppm, leaching time 10 hr, pH=10.5 and pulp density 40%.