Purification Of Magnetite Concentrate And Study On Pre-sintered Sr-Ferrite Powders

Demands for magnetic materials in many fields have greatly increased recently. In China, the main product of magnetic materials is permanent ferrite, which is usually made by using ferric oxide or iron concentrates as the raw material. But these raw materials are expensive and source-limited. It is significant in finding new kinds of raw materials. In this work, super-pure magnetite concentrates are used to substitute for ferric oxide to produce a high-grade Strontium ferrite powder.The requirement for the raw materials are TFe≥71%, SiO2≤0.5%r Al₂O₃≤0.1% and tiny content of other elements. In general, magnetite concentrates from concentration plants are not satisfactory with those requirements. Further purification for the concentrates is in need. In this work, magnetite concentrate from Jin Shan Dian concentrate plant attached to Wuhan Iron and Steel Corporation has been deeply purified by using a specialized spiral, produced a super-pure magnetite concentrate (TFe=71.5%, SiO₂=0.5%).The super-pure magnetite concentrate was first mixed with carbonate Strontium and then was sintered, producing a Strontium ferrite powder. Through optimizing the operation parameters such as mixing ratio, sintering atmosphere and sintering temperature, a much better Strontium ferrite powder with σ_s =74.38A·m²/kg,σ_r =43.68A·m²/kg , H_c=4005Oe has been produced.