No abstract

The low grade gold ore obtained from a local gold mine in Malaysia was characterized using X-ray fluorescence analysis and scanning electron microscope/ energy dispersive X-ray analysis for the deportment of gold. Acid digestion was carried out to determine iron, aluminium, sulphur and arsenic using ICP-OES. Chemical assaying methods viz aqua regia leaching and lead fire assay followed by acid digestion were conducted to determine the head grade of the gold ore. Assessment of gold using fire assay was found reliable to reduce the interferences from the gangue minerals. Despite the lower limit of detection of ICP-OES, there was no appreciable amount of gold detected in the samples leached using aqua regia because of the interference from the gangue minerals and also due to the interlocking of gold with aluminosilicates phase which require high pressure and temperature leaching using hydrofluoric acid to liberate the gold. ICP-OES analysis is reliable depending on the degree of liberation of gold during acid digestion. The head grade for this type of low grade gold ore was found to be in the range of 0.31 g/t to 0.55 g/t where the gold was highly associated with aluminosilicate minerals.

Refractory gold ore understudied showed traces amount of gold from X-ray fluorescence analysis. Phases identified are quartz, muscovite and calcite. Statistical approach using response surface methodology - central composite design were performed at varying concentration of NaCN, Pb (NO3)2 and H2O2. Cyanidation experiments were conducted at room temperature at pH 11. Using the response surface methodology followed by path of steepest ascent, gold cyanidation was found to be at 467.3 ppm NaCN, 94.96 ppm Pb (NO3)2 and 0.01M H2O2, at the vicinity towards the optimum condition where 88.97% Au extracted from the ore, equivalent to 1.7231 g/t Au.

No abstract