高铬型钒钛磁铁精矿煤基直接还原-磁选分离过程中钒和铬的行为（英文）

Behaviors of vanadium and chromium in coal-based direct reduction of high-chromium vanadium-bearing titanomagnetite concentrates followed by magnetic separation

高铬型钒钛磁铁精矿的煤基直接还原过程中·V2O3和FeO·Cr2O3的还原行为对其高效综合利用产生决定性的影响。采用XRD、SEM及EDS等手段对直接还原产物进行分析,分别考察碳铁摩尔比和温度对煤基直接还原-磁选分离过程中钒和铬行为的影响。结果表明:当碳铁摩尔比(n(C)/n(Fe))从0.8增大到1.4时,V和Cr的回收率分别从10.0%和9.6%增大到45.3%和74.3%。当n(C)/n(Fe)为0.8时,在1100~1250°C的温度范围内,V和Cr的回收率始终低于10.0%;而当n(C)/n(Fe)为1.2时,随着温度从1100°C升高到1250°C,V和Cr的回收率分别从17.8%和33.8%增大到42.4%和76.0%。当n(C)/n(Fe)低于0.8时,由于含碳还原剂的量不足,绝大多数FeO·V2O3和FeO·Cr2O3不能被还原成碳化物,且温度(1100~1250°C)对其还原行为的影响甚微。在更高的n(C)/n(Fe)下,由于含碳还原剂的量充足,FeO·V2O3和FeO·Cr2O3的还原率大幅提高,且更高的温度能有效地促进碳化物的生成。新生成的碳化物溶解在γ(FCC)相中,并在磁选过程中与金属铁同时回收。

The reduction behaviors of FeO·V2O3 and FeO·Cr2O3 during coal-based direct reduction have a decisive impact on the efficient utilization of high-chromium vanadium-bearing titanomagnetite concentrates. The effects of molar ratio of C to Fe n(C)/n(Fe) and temperature on the behaviors of vanadium and chromium during direct reduction and magnetic separation were investigated. The reduced samples were characterized by X-ray diffraction(XRD), scanning election microscopy(SEM) and energy dispersive spectrometry(EDS) techniques. Experimental results indicate that the recoveries of vanadium and chromium rapidly increase from 10.0% and 9.6% to 45.3% and 74.3%, respectively, as the n(C)/n(Fe) increases from 0.8 to 1.4. At n(C)/n(Fe) of 0.8, the recoveries of vanadium and chromium are always lower than 10.0% in the whole temperature range of 1100-1250 °C. However, at n(C)/n(Fe) of 1.2, the recoveries of vanadium and chromium considerably increase from 17.8% and 33.8% to 42.4% and 76.0%, respectively, as the temperature increases from 1100 °C to 1250 °C. At n(C)/n(Fe) lower than 0.8, most of the FeO·V2O3 and FeO·Cr2O3 are not reduced to carbides because of the lack of carbonaceous reductants, and the temperature has little effect on the reduction behaviors of FeO·V2O3 and FeO·Cr2O3, resulting in very low recoveries of vanadium and chromium during magnetic separation. However, at higher n(C)/n(Fe), the reduction rates of FeO·V2O3 and FeO·Cr2O3 increase significatly because of the excess amount of carbonaceous reductants. Moreover, higher temperatures largely induce the reduction of FeO·V2O3 and FeO·Cr2O3 to carbides. The newly formed carbides are then dissolved in the γ(FCC) phase, and recovered accompanied with the metallic iron during magnetic separation.