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热力学分析了铝还原剂从MgO、2MgO·B2O3和3MgO·B2O3中提取金属镁的化学反应。实验研究了制团压力、CaF2添加、还原温度、还原剂用量等对氧化镁还原率的影响。结果表明,适当地提高反应物料的制团压力有利于改善氧化镁还原率,但较大的制团压力会导致球团孔隙率降低,从而阻碍了产物Mg蒸气的释放以及氧化镁还原过程。对还原渣的X射线衍射分析表明,铝热还原生成的Al2O3会先与CaO结合。添加少量的Ca F2有利于氧化镁的还原,CaF2与还原渣结合成11CaO·7Al2O3·Ca F2。添加3%的CaF2,制团压力为90 MPa,在1200℃下还原120 min,氧化镁的还原率为85%,铝利用率为74%。
Thermodynamic analysis of aluminum reducing agent from MgO, 2MgO · B2O3 and 3MgO · B2O3 in the chemical reaction of magnesium metal. The effects of system pressure, addition of CaF2, reduction temperature and the amount of reducing agent on the reduction rate of magnesia were studied experimentally. The results show that properly increasing the pressure of the reaction mixture can improve the reduction rate of magnesia. However, the larger pressure of the pellets leads to the decrease of the porosity of the pellets, which hinders the release of the product Mg vapor and the reduction of magnesia. X-ray diffraction analysis of the reduction slag showed that the Al2O3 formed by the thermal reduction of aluminum was firstly combined with CaO. Adding a small amount of Ca2 F favors the reduction of magnesia, and CaF2 combines with the reduced slag into 11 CaO7Al2O3 Ca2 F2. Adding 3% CaF2, the system pressure is 90 MPa, reducing at 1200 ℃ for 120 min, the reduction rate of magnesium oxide is 85% and the utilization rate of aluminum is 74%.