氟化钙催化碳热还原氧化镁的实验研究

Experimental study on carbothermic reduction of magnesia by calcium fluoride as a catalyst

首先比较了4种碳质还原剂对MgO的还原能力,得到的还原效果依次为:焦炭>木炭>活性炭>石墨。选取还原最佳的焦炭作为还原剂进行正交实验,结果表明焦碳的粒度影响最大,其次是时间和碳配比,而温度的影响相对较小。另外,添加氟化钙(CaF2)可以加速MgO的还原,使之在较低温度下的还原率增加。在1500℃×1h时,添加3%(质量分数)CaF2的MgO还原率从67%提高到了99%,而在1400℃×1h时,添加5%CaF2的MgO还原率也达到91%。

The reducibility of four carbonaceous reducing agents selected for magnesia （MgO） were coke 〉 char- coal 〉activated charcoal〉graphite, primarily determined by reduction rates. With the optimal coke as a reduc- ing agent, the orthogonal experiment of MgO reduction was carried out. The results have showed that the parti- cle size of coke was most important, followed by soaking time, carbon content and least-important temperature. Moreover, the introduction of calcium fluoride （CaF2） into the reduction system can accelerate the reduction and therefore increase reduction rates at lower temperature. At 1500℃/lh, the reduction rate with 3%CaF2 in- creased from 67% to 99% and at 1400℃/lh that with 5% CaF2 up to 91%.