This study investigates the reactions of Na_2SO_4 and its effects on iron and nickel reduction in the roasting of a high-iron and low-nickel laterite ore through gas composition, X-ray diffraction, and scanning electron microscope analyses. Results showed that a reduction reaction of Na_2SO_4 to SO_2 was performed with roasting up to 600℃. However, no clear influence on iron and nickel reductions appeared, because only a small amount of Na_2SO_4 reacted to produce SO_2. Na_2SO_4 reacted completely at 1000℃, mainly producing troilite and nepheline, which remarkably improves selective reduction of nickel. Furthermore, the production of low-melting-point minerals, including troilite and nepheline, accelerated nickel reduction and delayed iron reduction, which is attributed to the concurrent production of magnesium magnetite, whose structure is more stable than the structure of magnetite. Reduction reactions of Na_2SO_4 resulted in weakening of the reduction atmosphere, and the main product of Na_2SO_4 changed and delayed the reduction of iron. Eventually, iron metallization was effectively controlled during laterite ore reduction roasting, leading to iron mainly being found in wustite and high iron-containing olivine.
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机译：Cumulative reduction of friction and size effects in micro milling through proper selection of coating thickness of TiAlN coated tool: Experimental and analytical assessments
