Fe_2O_3转变为Fe_3O_4粉末的微波碳热还原

Microwave carbothermic reduction from Fe_2O_3 to Fe_3O_4 powders

以活性炭为还原剂及以氩气为保护气,采用微波碳热还原的方法,将弱磁性的Fe2O3还原成强磁性的Fe3O4,并研究焙烧温度、保温时间以及SiO2粉末的加入对其还原焙烧成分及磁化效果的影响规律.结果表明：在配碳量一定的条件下,焙烧温度是微波碳热还原的关键因素,随着温度的升高,还原产物中Fe3O4的含量发生有规律的变化;650℃、保温5 min的条件下经微波还原后生成了纯Fe3O4粉末,其磁化率和还原度分别达到理论值2.33和11.11%;含SiO2的Fe2O3粉末在750℃以上进行微波还原,会生成大量的硅酸亚铁和氧化亚铁,导致Fe3O4含量降低,恶化还原焙烧指标,所以微波磁化焙烧的最佳温度应在570~650℃.

A microwave carbothermal reduction process of weakly magnetic Fe2O3 powders to ferromagnetic Fe3O4 powders was experimentally studied with argon gas as a protective gas and activated carbon as a reduetant. The influences of roasting temperature, holding time and SiO2 addition on the ingredients of reduced resultants and the magnetization effect of Fe2O3 powders were discussed. Under quantificational carbon, roasting temperature is a key factor of the microwave carbothermal reduction. The content of Fe3O4 in reduced resultants regularly changed with the roasting temperature increasing. Pure Fe3O4 powders were made at a roasting temperature of 650 ℃ for a holding time of 5 min, and their magnetisability and percent reduction reach the theoretical values of 2.33 and 11.11% , respectively. Above the roasting temperature of 750 ℃ , a plenty of FeSiO4 and FeO formed in reduced resultants after the microwave carbothermal reduction of Fe2O3 powders containing SiO2 , making Fe3O4 in reaction resultants decrease and the magnetization effect worsen. It is concluded that the best boasting temperature of Fe2O3 powders is from 570 ℃ to 650 ℃.