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通过热力学分析计算,给出了镍钼矿直接热还原的ΔGΘ-T图,用于直观分析不同温度下镍钼矿中矿物的还原过程,并在此基础上进行低品位镍钼矿加钙焙烧及硅铁直接热还原实验。研究表明:镍钼矿原有工艺的焙烧温度为580~620℃,反应速率低,焙烧时间长,升温会增加钼的挥发,加钙氧化焙烧可以将焙烧温度提高到700℃,提高了反应速率,并且可以将钼固定在矿物中,生成稳定的钼酸钙,减少氧化钼的挥发,起到良好的固钼作用。对镍钼矿氧化焙烧、硅铁直接还原过程进行分析,绘制镍钼矿中硅铁还原在不同温度下各反应的热力学状态图。分析研究表明,低温下的固-固反应中,硅铁均可还原氧化钼,但铁对氧化钼的还原能力较弱,Fe不能还原Ca Mo O4;液-固反应中,硅可还原氧化钼、钼酸钙,但铁没有还原能力;在铁浴反应阶段及钢渣界面的反应,起还原作用的主要是硅。实验室中加钙焙烧-硅铁直接热还原工艺制备镍钼铁合金,镍、钼的收得率均在85%以上,焙烧过程中硫被Ca O固定在熔渣中,有利于环保。
Through thermodynamic analysis and calculation, ΔGΘ-T diagram of the direct thermal reduction of nickel-molybdenum ore is given for the visual analysis of the reduction process of minerals in the nickel-molybdenum ore at different temperatures, and on the basis of this, the low-grade nickel-molybdenum ore plus calcium roasting And ferrosilicon direct thermal reduction experiments. The results show that the calcination temperature of the original nickel-molybdenum mine is 580-620 ℃, the reaction rate is low, the calcination time is long, and the temperature increase will increase the volatilization of molybdenum. Calcination and calcination can increase the calcination temperature to 700 ℃ and increase the reaction rate , And can be fixed in the mineral molybdenum, generate stable calcium molybdate, reduce molybdenum oxide volatilization, play a good solid molybdenum role. The oxidation roasting of nickel-molybdenum ore, the direct reduction process of ferrosilicon were analyzed, and the thermodynamic state diagrams of each reaction of ferrosilicon reduction in nickel-molybdenum mine were drawn. The results show that ferrosilicon can reduce molybdenum oxide in the solid-solid reaction at low temperature, but the reduction ability of iron to molybdenum oxide is weak and Fe can not reduce CaMoO4. In the liquid-solid reaction, silicon can reduce molybdenum oxide , Calcium molybdate, but the iron does not have the ability to restore; in the iron bath reaction stage and steel slag interface reaction, mainly from the reduction of silicon. In the laboratory, calcined-ferrosilicon direct thermal reduction process was used to prepare nickel-molybdenum ferroalloys. The yield of nickel and molybdenum were over 85%. The sulfur was fixed in slag by CaO in the process of roasting, which was good for environment protection.