Investigation of leaching of nickel sulfide flotation tailings to recover valuable metals

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Department of Chemical Engineering


The global transition towards renewable energy, driven by low-carbon theories and technologies, has resulted in an increasing surge in the demand for critical and unique elements, of which nickel (Ni) and copper (Cu) are encompassed. In this investigation, using acid leaching, the recovery of such elements from polymetallic tailings to supplement conventional extraction processes was studied. The effective leaching parameters were investigated and optimized to enhance the simultaneous recovery of Ni, Cu, cobalt (Co), chromium (Cr), and manganese (Mn) from the tailings sample. To this end, the response surface methodology (RSM) was employed, with sulfuric acid (H2SO4) concentration (0–20 g/L), ethylenediaminetetraacetic acid (EDTA) concentration (0–20 g/L), ferric chloride (FeCl3) concentration (0–20 g/L), leaching temperature (20–80 °C), and leaching time (4–12 h) as independent variables. The analysis of variance depicted that ferric chloride concentration was the most prominent process parameter for the recovery of Ni, Cu, Co, and Mn. The recovery of Cr was contingent to leaching temperature and sulfuric acid addition. Ensuing tests under the optimal conditions resulted in the recovery of 100.0 % Cu, 89.8 % Co, 42.1 % Cr, and 100.0 % Mn in addition to 93.7 % Ni. The kinetics was also studied using the shrinking-core model. Kinetic data indicates that the dissolution of Ni, Cu, Co, and Cr is governed by the chemically controlled model, while that of Mn by the diffusion control model. The activation energies as per the Arrhenius equation are estimated as 32.43, 36.78, 34.88, 24.02, and 29.18 kJ/mol for Ni, Cu, Co, Cr and Mn.

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Minerals Engineering