Recovery of Copper from a Waste Heat Boiler Dust Leach Liquor using LIX 84I and LIX 622N

Abstract

The dust collected from the waste heat boiler of a copper plant was leached with sulfuric acid and the leach liquor contained 31.63 kg/m3 Cu, 14.78 kg/m3 Fe, 2.21 kg/m3 Zn, 0.26 kg/m3 Co, 0.09 kg/m3 Ni, and 0.23 kg/m3 Cd. The iron content in the leach liquor was precipitated out using Ca(OH)2 and from the filtrate copper was extracted with the extractants LIX 84I and LIX 622N in kerosene. Extraction of copper with either extractant increased with increasing equilibrium pH and extractant concentration. The McCabe-Thiele plots for quantitative extraction of copper indicated 3-stages at O:A ratio of 3:2 with 30% extractants. The counter-current extraction study showed 0.21 kg/m3 and 6.77 g/m3 copper in the third stage raffinates of LIX 84I and LIX 622N indicating 98.64% and 99.95% extraction, respectively. For extraction of a mole of copper ion, two moles of the extractant was required to release two moles of hydrogen ion to the aqueous phase. The quantitative stripping of copper from the loaded organic phases of LIX 84I and LIX 622N with 180 kg/m3 H2SO4 was possible in 3-stages at O:A ratio of 3:1 and 3:2, respectively. The thermodynamic parameters such as ΔH, ΔG, and ΔS were calculated for both the systems. The enthalpy change (ΔH) values were positive for extraction of Cu with either extractant indicating the processes to be endothermic. The IR spectra indicated the association of phenolic-OH group of oxime molecules in the formation of copper complexes.