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The phase transformation of high-magnesium laterite ore were investigated during the reduction roasting process. In the absence of sodium carbonate [Na 2 CO 3 ], the X-ray diffraction results indicate that the [Fe Ni] alloy existed in ore in the form of taenite. The taenite particles is ne and the size is approximately 30-40 nm, which indicate that the nickel and iron are not migrated and aggregated during the non-smelting reduction roasting process. In the presence of sodium carbonate, the intensity of [Fe Ni] alloy phase increases; the taenite diffraction peaks disappears, corresponding to the appearance of kamacite. The results of SEM images show that the [Fe Ni] alloy particle size has a signi cant increase with the addition of Na 2 CO 3 . Based on the theoretical analysis, the pivotal role of Na 2 CO 3 may be mainly attributed to the Na + , which could in ltrate into the crystal lattice of FeO, leading to the lattice distortion. Furthermore, the sodium carbonate would be decomposed at high temperature, and the generated CO 2 could promote the Boudouard reaction which produced the CO to enhance the reduction of metallic oxides within ore.

This work investigates the in uence of calcium chloride addition on coal-based reduction roasting low-nickel garnierite ore, and which is most evident in nickel enrichment and ferronickel particles aggregation. The results demonstrate that a concentrate with 11.83% nickel, corresponding to a nickel recovery of 97.38%, was obtained when the ore was reduced at 1150 C for 40 min in the presence of 12 mass% CaCl 2 ·2H 2 O, followed by magnetic separation at 250 mT. Compared with the ore reduced without calcium chloride, the nickel enrichment ratio of the concentrate was increased from 3 to 14 by the addition of 12 mass% CaCl 2 ·2H 2 O. Duing to the vaporization of the nickel chloride formed and the emergence of a new reactive surface, the addition of calcium chloride makes NiO in the garnierite easier to be reduced. The X-ray diffraction and scanning electron microscopy and energy dispersive spectrometry (SEM-EDS) studies show that metallic nickel was mainly enriched into a kamacite phase, and the presence of CaCl 2 ·2H 2 O signi cantly accelerated the aggregation and growth of ferronickel particles, attributing to the vaporization and precipitation of nickel chloride on carbon surface together with ferrou chloride.