Physicochemical factors affecting leaching of laterite ore in hydrochloric acid

The effect of physicochemical factors on laterite ore leaching in hydrochloric acid was investigated in this study. The results showed that the valuable metals such as nickel and cobalt could be extracted effectively at the leaching conditions as follows: acid concentration was 8 mol/L, the particle size of samples were 100% passing 0.15 mm, the stirring speed was 300 rpm, leaching temperature was 353 K, S/L ratio was 1:4 and leaching duration was 2 h. The extraction of nickel and iron presented a linear correlation, which demonstrated nickel associated in iron ore, and cobalt dissolution was not consistent with iron dissolution which indicated that the distribution of cobalt were not uniform in the iron oxide crystals and existed in other minerals, and this result had also been demonstrated by mineralogical studies. To investigate the stability of different minerals in the leaching condition listed above as well as the influence of nickel and cobalt on their dissolution in such condition, the minerals dissolution order was studied by X-ray diffraction (XRD) according to determination of the leaching residues and chemical composition of the leaching solution, and the result order was goethite > lizardite > magnetite > hematite.