Pressure oxidative leaching of copper concentrate

Abstract

This study investigated the oxidative leaching of copper concentrate using a mixture of ferric ions and sulfuric acid solutions. We examined the effects of various parameters, including temperature, initial sulfuric acid concentration, and slurry filtration conditions. At lower temperatures (150 °C), the leaching process resulted in the elemental sulfur and jarosite minerals formed in the solid residue. In contrast, at higher temperatures (190 °C), the solid residue contained jarosite and hematite, the most elemental sulfur-oxidizing to sulfuric acid. Under optimal conditions, a leaching temperature of 190 °C, a concentrate-to-leaching solvent (Fe³⁺ 5 g l^-1 and H₂SO₄ 50 g l^-1) ratio of 1:8, an oxygen pressure of 1.0 MPa, and a solid phase particle size of less than 20 μm the dissolution rate of copper reached 98% after three hours. When the sulfuric acid concentration was increased from 30 g l^-1 to 100 g l^-1, the amount of copper was increased from 40 g l^-1 to 48 g l^-1.  Furthermore, rapid filtering of the leaching solution without cooling helped retain most of the iron in the solid phase, resulting in a relatively pure solution. The solid residue was analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM).