硼镁石与碳酸钙混合煅烧-还原提镁研究

基于硼镁石与碳酸钙混合料的煅烧实验和真空铝热还原实验,研究了碳酸钙量、成型压力、煅烧条件对熟料物相、原料烧损率、镁还原率的影响.结果表明,添加碳酸钙,在煅烧过程中Ca O可置换出Mg3B2O6,Mg2B2O5中的Mg O,并且在还原过程中Ca12Al14O33的形成有利于Mg O的还原.煅烧温度过高会降低Mg O活性,不利于后续铝热还原.增大成型压力,有利于Ca3B2O6的形成.但成型压力过大,在相同煅烧条件下,矿石的烧损率较低,镁还原率较低.碳酸钙与硼镁石以mCa/ms=1.9配比混合,在90 MPa压力制团,在1100℃下煅烧120 min后,铝热还原的镁还原率可达85%以上,实现硼、镁有效分离.

Study on Calcination of Szaibelyite and Calcium Carbonate Mixture for Magnesium Extraction

Calcination of szaibelyite and calcium carbonate mixtures and extraction of magnesium from the calcined products by vacuum aluminothermic reduction were experimentally studied. The effects of calcium carbonate addition， forming pressure and calcination temperature on phases in the calcination products， the burning loss ratio of the mixtures and reduction ratio of magnesium oxide were discussed. The results indicated that most of the MgO were replaced from Mg₃B₂O₆ and Mg₂B₂O₅ by CaO during the calcination process of the mixtures. Moreover， the formation of Ca₁₂Al₁₄O₃₃ favored the reduction of MgO. Although it was favorable for the formation of Ca₃B₂O₆， higher forming pressure caused lower burning loss ratio of the mixture and lower reduction ratio of MgO. The reduction ratio of MgO was greater than 85% when the mixture with m_○Ca/m_○s = 1.9 was formed at 90MPa and then calcinated at 1100°C for 120min.