Al-Si-Fe合金真空热法炼镁过程动力学

Vacuum Thermal Reduction Kinetics of Calcined Dolomite with Al-Si-Fe Alloy

采用收缩未反应核模型研究Al-Si-Fe合金真空热还原煅后白云石制镁过程动力学,考察了制团压力、还原温度(T)和添加氟盐对镁还原率(R)的影响.结果表明,在40～150MPa内,制团压力越大,镁还原率越高;添加氟盐可加快还原反应速率,提高镁还原率.确定了还原过程最佳工艺条件为:还原温度1413K、还原时间(t)120min、真空度4Pa、制团压力150MPa、CaF2添加量3%.在1373～1413K内,还原过程为一级反应,由还原剂通过固体产物层的内扩散步骤控制,宏观动力学方程为1+2(1-R)-3(1-R)2/3=0.194exp(-8.38×103/T)t,表观活化能为69.7kJ/mol.

Vacuum thermal reduction kinetics of calcined dolomite with Al-Si-Fe alloy was studied using shrinking unreacted-core model. The effects of pellet forming pressure, reduction temperature （T）, and villaumite on reduction rate （R） of calcined dolomite were investigated. The results show that within the pellet forming pressure from 40 to 150 MPa, the reduction rate is increased with increasing of the pressure. Villaumite can accelerate the reduction rate and then increase the reduction rate, and the optimal conditions are reduction temperature 1413 K, reductiontime （t） 120 min, vacuity 4 Pa, pellet forming pressure 150 MPa and addition of CaF2 3%. The reduction process is the first order reaction and controlled by diffusion of reductant in solid product layer. The equation for the reduction kinetics is 1＋2（1-R）-3（1-R）^2/3=0.194exp（-8.38×10^3/T）t, and the apparent activation energy 69.7 kJ/mol.