CaF_(2)对拜耳法赤泥碳热熔融还原提铁的影响

Effect of CaF_(2)on Extracting Iron from Bayer Red Mud by Carbothermal Smelting Reduction

基于拜耳法赤泥碳热熔融还原提铁过程中渣铁分离难的问题,研究了添加CaF_(2)对炉渣凝固物相、高温黏度、熔化性温度、金属直收率和金属出炉聚集状态的影响。结果表明,拜耳法赤泥碳热熔融还原炉渣的主要凝固相为钙铝黄长石、钙钛矿和霞石,添加CaF_(2)后,炉渣凝固相中出现了萤石相;添加CaF_(2)能够降低拜耳法赤泥炉渣的高温黏度和熔化性温度,有助于改善赤泥炉渣的流动性和提高金属的直收率;从改善幅度和环保考虑,CaF_(2)适宜添加量为2%左右;从未添加CaF_(2)到添加2%CaF_(2)时,1550℃时的炉渣黏度值从0.65 Pa·s降低到0.61 Pa·s,熔化性温度从1401℃降低至1355℃,金属直收率从86.49%提高到87.87%。

Based on the difficulty of iron-slag separation in the process of iron extraction from Bayer red mud by carbothermal smelting reduction,CaF_(2)was added into the Bayer red mud and the effect of different CaF_(2)addition on solidified phases,viscosity,melting temperature of the slag,metal recovery and metal aggregation state after outflow from the furnace were studied.The results show that the main solidified phases of the Bayer red mud slag after carbothermal melting reduction are gehlenite,perovskite and nepheline.After adding CaF_(2),fluorite appeared in the slag.Furthermore,adding CaF_(2)can reduce the high temperature viscosity and melting temperature of the red mud slag,and improve the fluidity and the metal recovery.However,from the perspective of improvement and environmental protection,the suitable addition of CaF_(2)is about 2%.When the addition of CaF_(2)increases from 0 to 2%,the slag viscosity at 1550℃decreases from 0.65 Pa·s to 0.61 Pa·s,the melting temperature decreases from 1401℃to 1355℃,and the metal recovery rate increases from 86.49%to 87.87%,respectively.