The influence of pyrite pre-oxidation on gold recovery by cyanidation
ABSTRACT The influence of pyrite pre-oxidation in alkaline solutions on gold recovery by cyanidation from Twin Creek refractory gold ore in which pyrite was identified as the major sulfide mineral has been investigated with the aid of electrochemical measurements, leaching experiments, and direct analysis of reaction products for selected residues. It was found that gold recovery by cyanidation in bottle roll experiments mainly depended on the extent of pyrite pre-oxidation. The rate of pyrite oxidation in alkaline solutions measured by electrochemical measurements, including chronoamperometry and linear sweep voltammetry, increased with an increase in pH, potential, and temperature. All alkaline reagents used for the electrochemical measurements, NaOH, NH4OH, Na2CO3 and Ca(OH)2, showed a similar effect on pyrite oxidation kinetics. However, the results of alkaline pre-oxidation for pyrite of the Twin Creek refractory gold ore suggested that NaOH and Na2CO3/Ca(OH)2 were superior to Ca(OH)2. Without pre-oxidation, cyanide leachable gold was found to be only 20% which could be increased to 70% under appropriate pre-oxidation conditions. At the same time, cyanide consumption decreased from 2.5 kg/t ore to 1.5 kg/t ore.Selected residues after pre-oxidation and cyanidation were examined by X-ray diffraction. Backscattered electron images of pyrite particles in these residues were taken. The reaction products at the surface of pyrite particles were found to be iron-, silicon-, and calcium-bearing compounds with variable amounts of sulfur as determined by X-ray energy dispersion analysis. Additionally, some mineral fines, such as aluminum and/or potassium-bearing minerals, were found to be present at the partially oxidized pyrite surface.
- Transactions of Nonferrous Metals Society of China 12/2011; 21(12):2744-2751. DOI:10.1016/S1003-6326(11)61118-7 · 1.00 Impact Factor
- World Gold 2013, Queensland, Australia; 01/2013
Conference Paper: Pyrite Flotation: A Review[Show abstract] [Hide abstract]
ABSTRACT: Consumption of base metals has been increasing continuously in parallel with the technological improvements over the world. This demand has resulted in the need to enhance processing of complex sulfide ores, which are the primary sources of base metals. Complex sulfide ores are concentrated mainly through flotation. Sulfide minerals are semiconductors, and pyrite is the major gangue mineral associated with these ores. Main interest in the processing of complex sulfide ores has focused on the rejection of pyrite and selectivity problem that arises owing to the similar electrochemical behavior of pyrite to the other sulfide minerals in a complex ore. Vast number of research has been conducted on pyrite flotation, producing significant data on this particular matter. This review aims to gather these data with an attempt to evaluate pyrite flotation as a whole picture. In this respect, roles of different flotation agents, pH and electrochemical conditions on the hydrophobicity and floatability of pyrite were discussed.XIIth INTERNATIONAL MINERAL PROCESSING SYMPOSIUM 2010; 10/2010