Abstract
An option to improve the leaching efficiency of chalcopyrite is pretreatment prior to leaching. Pretreatment variables, such as the curing time and the addition of chloride, can increase the kinetics of copper extraction, particularly for sulphide ores. However, there has been little research on the topic. The reactions that govern this phenomenon have not been clearly identified. In this study, the effects of sulphuric acid and sodium chloride agglomeration and curing on chalcopyrite leaching were evaluated at various temperatures: 25, 50, 70, and 90 °C. The pretreated ore and leach residues were characterised by X-ray diffraction, scanning electron microscopy, and reflected light microscopy. Under the conditions of 15 kg/t of H2SO4, 25 kg/t of NaCl, and 15 days of curing time (as pretreatment), the following products were identified: CuSO4, NaFe3(SO4)2(OH)6, Cu2Cl(OH), and S0. Increasing the curing time and leaching temperature increased copper leaching. The copper extraction was 94% when leaching at 90 °C after pretreatment with 50 g/L of Cl− and 0.2 M of H2SO4. Elemental sulphur, jarosite, and copper polysulphide (CuS2) were detected in the leaching residues.
Highlights
In the transition of Chile from a developing economy to a developed economy, mining plays a key role in sustaining the economy with care to minimise the ecological impact on the environment and to promote social growth [1]
Copper producers in Chile are switching to use concentration processes due to the mineralogy shifting to primary copper sulphides—
The samples were filtered (0.2 μm), and the metal concentrations in the filtrate were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES)
Summary
In the transition of Chile from a developing economy to a developed economy, mining plays a key role in sustaining the economy with care to minimise the ecological impact on the environment and to promote social growth [1]. Innovation and new mineral processing alternatives are essential to maintaining copper production [2,3]. According to the Chilean Copper Commission (Cochilco), 27.3% of Chilean copper is produced using hydrometallurgy [4]. Copper production by hydrometallurgy is expected to decrease 11.6% by 2029 owing to the depletion of the copper oxide ores in Chilean copper deposits. Copper producers in Chile are switching to use concentration processes due to the mineralogy shifting to primary copper sulphides—. Chalcopyrite (CuFeS2 ) is the most abundant copper-bearing resource, accounting for more than 70% of global copper reserves [5]
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