This paper introduces an application of chlorination roasting process followed by hot-acidulous water leaching that could cause a high extraction selectivity of Ni, Co and Mn over Fe and Mg which can concentrate Ni and Co in laterite ores. Thermodynamic analysis of possible chlorination reactions in roasting process was calculated and the Predominance Area Diagram of Ni-Co-Cl-H-O was shown to indicate the effect of partial pressure of HCl and H2O on the stability of NiCl2 and CoCl2. The mixture of NaCl and MgCl2 center dot 6H(2)O was selected as chloride agent and the chlorination mechanism was discussed comprehensively. The results show that the leaching rates of Ni, Co, Mn, Fe and Mg are 87%, 58%, 53%, 32% and 5.4% respectively at the optimal conditions, which showed that Ni, Co and Mn could be extracted effectively and the extraction of Fe and Mg was suppressed simultaneously. The Ni/Fe ratio and Ni/Mg ratio can reach 0.97% and 0.25% in leaching solution which can increase 15 times and 8 times respectively in comparison with the Ni/Fe and Ni/Mg ratio in raw ore. (C) 2016 Elsevier B.V. All rights reserved.