Solvent Extraction of Copper from Sulfate Leach Liquor of Chalcopyrite Concentrate: Mitigation Strategies for Iron Coextraction

Abstract

In this study, solvent extraction of copper (Cu) from sulfate leach liquor of chalcopyrite concentrate was investigated using LIX 984N as the extractant and kerosene as the diluent. The effects of pH (1-4.5), organic-to-aqueous phase ratio (O/A, 1/3-3/1), extractant concentration (3%-9% v/v), diluent type (kerosene, benzene, and hexane), and temperature (25 degrees C-55 degrees C) on the extraction efficiency were systematically evaluated. Stripping experiments were also carried out using sulfuric acid at different concentrations (0.75-3 M) and agitation rates (200-600 rpm). The results revealed that up to 98.1% of copper could be extracted at pH 4.5, O/A = 1, 6% (v/v) LIX 984N, and 25 degrees C when hexane was used as the diluent. However, a significant amount of iron (20%-28%) was also coextracted into the organic phase under similar conditions, which poses challenges for downstream electrowinning. Complete stripping of copper and iron was achieved at 1.5 M H2SO4 with the agitation of 500 rpm. These findings highlight the need for a preliminary iron removal step prior to solvent extraction to ensure selective copper recovery.