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As the high grade nickel sulfide ores are depleted, more and more attention has been put on low grade nickel laterite. In this paper, based on the process study of our lab team, the process of chloride segregation of laterite with the low Fe and high Mg ore from an area of foreign as raw materials was studied.By thermodynamic calculation, the thermodynamic equilibrium diagram of vapor composition was drawn. Applying FactSage software and database, phase diagram of the M-C-O, MO-SiO2, Ni-Fe-O, Ni-Fe alloy, Ni-Fe alloy magnetic and mixed chloride have been studied. In order to achieve good segregation effect, the system must be weak reducing atmosphere and high temperature. The production, water quenching at 850℃, should control the nickel mass fraction of nickel-iron alloy≥5%.To study the generation of hydrogen chloride, the reaction process of SiO2 and CaCl2 was studied:below 200℃, CaCl2·2H2O was dehydration. Between 200℃to 750℃, there was not valid reaction. Between 750℃to 800℃, with the ratio of SiO2 and CaCl2 2:1 and 1:1, the Ca2Si03Cl2 was generated, as the temperature increases, Ca2Si03Cl2 decomposed with hydrogen chloride gas released; with the ratio 1:2, Ca3Si05-CaCl2 was generated, as the temperature increases, it did not break down, however, excessive calcium chloride volatilized due to vapor pressure decreased.The researches of chlorination process of metal oxide indicated that at about 600℃, serpentine decomposed, which increased the reaction interface of the chlorination process. After 700℃, a higher HCI partial pressure was needed. This Causes the rate of nickel chloride decreased first and then increased as the temperature increased from 600℃～1000℃. Based on kinetics calculations of chlorination of nickel oxide, the reaction accords with the "shrinking core model" of gas-solid reactions, which was controlled by the internal diffusion, the apparent activation energy value was 32.42kJ·mol-1.The results of the formation and growth process of metal particles showed that with the increase of steam pressure, the concentrate grade decreased and the yield of nickel increased gradually. Nickel-iron alloy particles can segregate on the carbon surface and rough surface of silicate. The growth of particles was easy on the carbon surface, but on the surface of silicate particles, it was very difficult. At low temperature, the particles growth mechanism is small nickel-iron alloy particles move to a more favorable position which is the contact point of two particles; At high temperature conditions, the particles growth mechanism is the small melting particles evaporated and adsorbed to the surface of large one.The studies to phase transformation of chloride segregation revealed that with the increase of temperature, between 400℃and 600℃, magnesium carbonate decomposed; Between 600℃and 700℃, the serpentine phase decomposes and disappeared, replaced by the Fe-rich and Ca-rich olivine phase. It was apparent that the phases formed were stable and the process was not reversible during reduction at elevated temperatures.
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