硅热法炼镁还原过程熔融黏结机理及控制

Mechanism and Control of Fusion and Agglomeration in Indirectly Heated Silicothermic Reduction

黏罐结釉是制约外热式硅热法炼镁技术发展的主要难题。通过大量热物理化学试验及对低熔点复合氧化物的物相检测分析,系统揭示了造成黏罐结釉的固相催化反应熔融黏结机理:硅热法炼镁还原过程中,FeO或Fe_(2)O_(3)的生成及其与SiO_(2)或CaO生成的复合氧化物是造成给熔融黏结问题的核心因素,通过原料杂质控制和还原过程工艺控制,以减少FeO或SiO_(2)的含量,能有效控制渣球的软化程度及黏结程度。研究结果能够为外热式硅热法炼镁新型还原罐的设计优化提供基础理论指导。

Sticking and glaze in retort is impeding development of magnesium production technology by indirectly heated silicothermic reduction method.At present,it is still unclear to the intrinsic mechanism of fusion and agglomeration when the sticking and glaze occurs during production.There is no reliable solution to control the fusion and agglomeration.Through a large number of thermophysical and chemical experiments,and phase detection and analysis on low-melting-point composite oxides,it was systematically revealed the mechanism of catalytic reaction causing the fusion and agglomeration,i.e.,the formation of FeO or Fe_(2)O_(3) and the composite oxides formed with SiO_(2) or CaO are the core factors causing fusion and agglomeration problem in the process of magnesium reduction by silicon thermal smelting.The softening degree and bonding degree of slag ball can be effectively controlled by controlling raw material impurities and reduction process so as to reduce content of FeO or SiO_(2).The scientific and reasonable control indexes of raw material impurity and the corresponding control measures were given.The results can provide basic theoretical guidance for designing the new retort of indirectly heated silicothermic reduction process.