Search

In this paper, thermodynamic analysis on reduction of lateritic nickel ore by CO2/H2 mixed gas was performed based on activity theory. Effects of CO2/H2 ratio and temperature on selective reduction of laterite ore were investigated. The calculation result shows that the metallization of Fe and Ni could be promoted by each other because of the variation of the Fe and Ni activity, which accounts for the inescapability of Fe metallization. When laterite nickel ore was reduced by mixed gas with a CO2/H2 ratio of 9/1 and a gas flow of 100mL/min at 800°C for 1h, a product with a Ni metallization rate over 95% and a Ni/Fe ratio as much as 2.6 was prepared.

In this paper, mineralogical phase transformations of Indonesia nickel laterite ores are studied during calcinations, the thermodynamics of process are also investigated. Different factors that affect the reduction of the laterite ores are tested and analyzed by Differential Scanning Calorimeter (DSC), X-ray Diffraction (XRD), Brunauer Emmett Teller (BET) and Scanning Electron Microscope (SEM). The results show that during calcination process, goethite is dehydrolyzed by removing structural water at about 300°C, which then transforms to hematite, and serpentine decomposes at around 600~700°C, leading to formulate olivine if agglomerating at higher temperature. By thermodynamics calculation, the goethite dehydration temperature is under 100°C, and about 200°C for serpentine decomposition. It might be the inclusions in ore which make laterite become hard to decompose.