Carbonaceous gold ore obtained from the Prestea Goldfield, Ghana, was fractionated into its organic components by means of NaOH leaching, benzene treatment, and hydrofluoric acid leaching. The initial ore as well as the extracted components were characterized by chemical analysis and infrared spectroscopy. The results indicate that the ore is dominated by silicates (∼53% SiO2) and contains about 5% total carbon. The hydrocarbon extract (0.27%) obtained from the benzene treatment analyzed 66.9% C, 18.2% S, 10.5% H and 1.7% O. The infrared spectrum of this material showed a predominance of CH3, CH2, CH and C = O groups suggesting the presence of long-chain hydrocarbons. No extraction of a humic acid fraction was achieved. The major organic component was the carbon extract (3.9%) which analyzed 59.4% C, 10.6% Al2O3 and 5.6% TiO2. The surface chemistry of the carbonaceous ore and the carbon extract was investigated by means of electrophoretic mobility and gold uptake measurements. Both the ore and the carbon extracts were found to be negatively charged in the pH range 3 to 11, with the negative charge increasing with pH. Gold adsorption from aqueous cyanide solution was found to be enhanced by increase in H+ and Ca2+ ion concentrations. The results are interpreted in terms of coulombic and specific chemical interactions.
All Science Journal Classification (ASJC) codes
- Geotechnical Engineering and Engineering Geology
- Geochemistry and Petrology