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热力学研究得出:当系统残余压力为100~10 Pa时,SiO2与碳反应在1465~1353 K以上即可生成Si和CO;在1329~1225 K以上即可生成SiC和CO;SiO2和还原剂碳及氟化铝在1464~1353 K以上反应生成SiF4和CO及铝。实验考察了真空低价氟化法炼铝过程中SiO2的分布。XRD表明:SiO2在低价氟化法炼铝过程中有五种走向:(1)被还原成SiC,存在于残渣相;(2)被还原为单质硅,再与还原出的铁生成硅铁,存在于残渣相;(3)SiO2与冰晶石生成铝硅酸盐进入气相中;(4)SiO2与冰晶石生成气态SiF4,再与冰晶石分解的氟化钠形成Na2SiF6进入冷凝相;(5)形成气态低价氧化硅,再在合适温度下分解为单质硅进入冷凝相。
Thermodynamic study shows that when the system residual pressure is 100 ~ 10 Pa, SiO2 and carbon react at above 1465 ~ 1353 K to form Si and CO; SiC and CO can be formed above 1329 ~ 1225 K; SiO2 and reductant Carbon and aluminum fluoride react above 1464-1353 K to form SiF4 and CO and aluminum. The experiment investigates the distribution of SiO2 in the aluminum refining process by the vacuum low-cost fluorination process. XRD shows that there are five orientations of SiO2 in the process of aluminum refining by the low-cost fluorination process: (1) it is reduced to SiC and exists in the residue phase; (2) it is reduced to elemental silicon and then to ferrosilicon , Exists in the residue phase; (3) SiO2 and cryolite to produce aluminosilicate into the gas phase; (4) SiO2 and cryolite to generate gaseous SiF4, and sodium silicate decomposition of cryolite to form Na2SiF6 into the condensate phase; (5) ) To form a gaseous low-cost silica, which is then decomposed to elemental silicon at a suitable temperature to enter the condensed phase.