Study On Solid Phase Reduction Of Silicon-magnesium Type Laterite Nickel Ore

The high-grade nickel-containing sulfide ores are becoming both depleted.Consequently,increasing attention is being paid to the nickel oxide-containing laterite ores.The paper introduces the current situation of global nickel resources and the development and utilization of nickel laterite resources.To reduce environmental pollution and improve the metallization rate of nickel and iron,the gas reduction for the garnieritic laterite ore(0.82%Ni and 9.67%Fe)was carried out.The results provide theoretical basis for the industrial application of garnieritic laterite ore.Firstly,the experimental study of hydrogen and methane low-temperature reduction of gaenieritic laterite ore was carried out respectively.The effects of reduction temperature,reduction time,hydrogen concentration and mineral size on the metallization rate of nickel and iron were investigated.The results showed that metallization rate of nickel and iron are 95%and 42%,respectively,under the conditions of reduction temperature of 600?,reduction time of 90 min and hydrogen concentration of 60 vol.%.When the particle size was less than 380 ?m,the effect of particle size on the metallization rate of nickel and iron was not obvious.When methane was used as a reducing agent,the metalification rate of nickel and iron in the reduced product was 91.17%and 23.67%,respectively,under the reduction temperature of 700?,the reaction time of 60 min and the methane concentration of 20 vol.%.After the gas-based low temperature reduction,a nickel-iron alloy was obtained by the low temperature hydrogen reduction.And the nickel oxide was almost completely reduced and most of the iron was reduced to iron low-priced oxide.In addition,the amorphous silicate recrystallized to form magnesium olivine hindered the reduction of nickel and iron.Under optimum conditions,the relative methane concentration(20 vol.%)is much lower than the hydrogen concentration(60 vol.%).Moreover,Reduction of low-grade nickel laterite ore by carbon monoxide to produce ferronickel was investigated by a thermo-gravimetric analysis(TGA)method.Non-isothermal reduction test with a fixed heating rate of 10?/min from room temperature to 1200? and isothermal reduction tests with temperatures ranging from 500 to 1100? were investgated.Model fitting method was employed to further determine the rate controlling step in the isothermal tests.Simultaneously,two groups TG experiments via varying the CO flowrates and sample mass were carried out to determine the diffusion of CO through the pores of the laterite ore sample bed is the controlling factor.These results indicated that the reduction rate increases with the increase of the reduction temperature from 500 to 1100? and the formation of forsterite(Mg2SiO4)inhibited the reduction degree.More and more alloy products are formed with the increase of the reduction temperature from 700 to 1100?.The apparent of activation energies increasing from 8.61 to 14.73 kJ/mol with the progress of the reaction.