永磁铁氧体粉体六价铬控制

Control technology of Cr^6+in permanent magnet ferrite powder

采用低氧化锶含量的高摩尔比配方体系及干燥窑尾气辅助加热的烘干方式,可有效消减产品中Cr^(6+)含量,使产品中Cr^(6+)含量<10ppm。当氧化铁与氧化锶的摩尔比为6.2时,产品的综合性能最优:Cr^(6+)含量为8ppm,剩磁Br为261m T,内禀矫顽力Hcj为311kA/m。干燥窑尾气辅助加热的烘干方式,可使产品中Cr^(6+)的含量稳定在7~8 ppm,并使物料的料面温度保持在300℃以下,减少烘干能耗50%。

Cr6+content in permanent magnetic ferrite powder can be effectively reduced by using formula system with high molar ratio of ferric oxide to strontium oxide and low strontium oxide content and drying method with auxiliary heating of exhaust gas from drying kiln.The Cr6+content in the product is less than 10 ppm.When the molar ratio of ferric oxide to strontium oxide is 6.2,the product has the best comprehensive performance:Cr6+content of 8 ppm,Br=261 mT,and Hcj=311 kA/m.The drying method of exhaust assisted heating in the drying kiln can stabilize the Cr6+content in the product at 7 to 8 ppm.And temperature of the material surface is kept at below 300℃,and energy consumption for drying is decreased by about 50%.