A study on extraction of copper using LIX 84-I and LIX 622N

The bulk sulphide precipitate obtained after addition of Na2S to the Fe- and Mn-free leach liquor of manganese nodule was leached with H2SO4 and the leach liquor contained 13 kg/m3 copper, 15.6 kg/m3 nickel, 2.6 kg/m3 cobalt, 2.6 kg/m3 zinc and 13.0 kg/m3 Na2SO4. Extraction of copper from this leach liquor was carried out with the extractants LIX 84-I and LIX 622N in kerosene. Extraction of copper increased with increasing equilibrium pH and extractant concentration with both the extractants. The quantitative extraction of copper was obtained in 4-stages at A:O ratio of 3:4 with 25% LIX 84-I and in 3-stages at 1:1 phase ratio with 25% LIX 622N. The counter-current extraction study showed 0.032 and 0.015 kg/m3 copper in the raffinate with LIX 84-I and LIX 622N indicating 99.75 and 99.88% extraction, respectively. The stripping of copper loaded LIX 84-I and LIX 622N increased with increasing H2SO4 concentration (10–120 kg/m3), but stripping of the latter was lower than the former. The stripping studies carried out with the copper spent electrolyte showed quantitative stripping of copper from the loaded organic in 3-stages at O:A ratio of 2:1 with both the extractants. The effect of various diluents such as cyclohexane, n-hexane, toluene, kerosene and xylene on extraction of copper was studied including the study of synergism due to the solvents.