Abstract
Chalcopyrite is the most abundant copper ore mined in Chile. Hydrometallurgical plants are currently changing to concentration by flotation-matte smelting deposits when oxide minerals run out and chalcopyrite appears in deposits. The change from hydrometallurgical processing to flotation is mainly dependent on whether comminution costs can be absorbed given the copper grade. It is important to develop alternative technologies to work profitably with low-grade copper sulphide ores. One alternative that has been recently studied is the pretreatment of low copper grade sulphide minerals, especially chalcopyrite, to improve leaching efficiency. The curing time, as pretreatment, improves dissolution kinetics and shortens leaching time. This study used a pure sample of chalcopyrite mineral with 28.5% copper. Chalcanthite (copper sulphate) represented 9% of total copper in the sample. The effect of curing time as a function of copper extraction prior to leaching was evaluated using different concentrations of sodium chloride (NaCl), potassium nitrate (KNO3) and sulphuric acid (H2SO4). A 23% copper dissolution was obtained prior to leaching using 25kg/t NaCl, 15kg/t H2SO4 and 15 days of curing time. The ANOVA analysis reported that curing time was the most important variable (56.4 and 54.7% of contribution) in tests with NaCl and KNO3. According to the results, KNO3 does not have a significant effect on copper extraction prior to leaching.
Highlights
This paper presents the results of a study on the effect of chalcopyrite pretreatment in chloride and nitrated media prior to leaching through moderate conditions, at room temperature
The potassium nitrate–sulphuric acid media system (15 kg/t H2SO4, 10 kg/t KNO3 and 15 days of curing time) as a leaching pretreatment resulted in a copper extraction of 12.93%
The analysis of variance (ANOVA) analysis indicated that this combination of variables
Summary
Similar conditions are proposed for the treatment of an industrial mineral whose the main contribution of copper is chalcocite and covellite [22] In other studies, such as that developed by Cerda et al [23], a maximum of 93% copper dissolution was obtained when the ore (chalcopyrite 1.2 wt%) was treated with 90 kg Cl/t ore, with 40 days of curing time at 50 ◦C in leaching flasks. A study developed by Hernández et al [24] used NaCl and NaNO3 in the pretreatment and subsequent leaching of an industrial mineral whose main copper contribution was chalcopyrite In this case, a maximum copper extraction of 58.6% was obtained, with the addition of 23.3 kg NaNO3/t, 19.8 kg NaCl/t and 30 days of curing time at 45 ◦C. The predictive results of the model support this assumption, it could be further confirmed by conducting additional experiments
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