用超纯铁精矿生产锶铁氧体预烧料及其焙烧动力学

Preparation of strontium ferrite powder by iron concentrate and its sintering dynamics

锶铁氧体是应用最广的永磁铁氧体 ,当前其生产原料主要是铁红和铁鳞 ,但这 2种原料来源有限 ,且价格昂贵 ,因此寻找质优价廉的锶铁氧体原料已成为当务之急 .作者采用分散与选择性聚团磁选新工艺制备出w(Fe) =71.88% ,w(SiO2 ) <0 .5 %的超纯铁精矿 .锶铁氧体预烧生产工艺是 :采用超纯铁精矿氧化和铁氧体生成反应 ,在配比n为 5 .6 ,精矿粒度低于 2 μm ,预烧温度为 15 5 3K ,保温时间超过 1h和添加剂适量的工艺条件下 ,制备出比饱和磁化强度σS>71.5A/ (m2 ·kg)的优质锶铁氧体预烧料 .用缺陷化学理论和焙烧动力学进行分析 ,结果表明 :Fe3+和Sr2 +通过O2 -晶格互相扩散并以Sr2 +扩散为主 ,在SrFe12 O19-Fe2 O3,SrO -SrFe12 O19界面发生固相反应 ,生成锶铁氧体 .

Strontium ferrite has been used widely. Nowadays, the main raw materials for strontium ferrite are Fe_2O_3 and Fe_3O_4, which are expensive and limited. So it is necessary to find new kinds of raw materials. Magnetite separation has been adopted to pretreat raw materials, and the superpure iron concentrate of w(Fe)=71.88%, w(SiO_2)<0.5% can be obtained. In the process of the preparation of strontium ferrite powders, the oxidation of the magnetite and the formation of strontium ferrite have been finished at the same time by using novel technique. Under the following condition, that is, molar ratio n is 5.6, size of concentrate is less than 2 μm, sintering temperature is 1 553 K, sintering time is more than one hour and proper reagents, the strontium ferrite powder with good results such as σ_S>71.5 A/(m2·kg) has been got. The study of the dynamics and the analysis of defect chemical theory on the reaction of the formation of strontium hexaferrites phase expresses that Fe 3+ and Sr 2+ mutually diffuse through the crystal lattice of O 2-, especially Sr 2+ diffusion is primary, the solid reaction for the appearance of strontium ferrite take places in the interfaces of SrFe_ 12O_ 19-Fe_2O_3 and SrO-SrFe_ 12O_ 19 respectively.