Research On The Mixed Rare Earth Tailings By Magnetization Roast-Weak Magnetic Separa-tion

Bayan Obo tailings contain a large number of valuable elements, among which the grade of iron and rare earth is13.00%and7.09%(REO) respectively. Therefore, it’s quite mea-ningful to utilize the tailings. Based on adequate research on the physicochemical properties of rare earth tailings, the magnetization roast-weak magnetic separation was adopted on the tailings. In order to study the transformation of iron during the magnetization roast, chemical analysis, XRD analysis, SEM analysis, TGA, hysteresis loop analysis were used to character-ize the iron.In the preliminary experiment, magnetization roast proved to be practicable. The ortho-gonal experiment sorted the factors that influence magnetization roast as:temperature>pro-portion of carbon> roasting time. Under furnace cooling, temperature at650℃and C/O at3.85for2.5h could obtain the optimal magnetization rate2.36. Under air cooling, temperature at570℃and C/O at3.85for0.5h could obtain the optimal magnetization rate2.40. Under water cooling, temperature at570℃and C/O at3.85for1.5h could obtain the optimal magne-tization rate2.51. The magnetic results were better when temperature at570℃and C/O at3.85for0.5h by air cooling and water cooling. After magnetic separation iron grade was41.30%and iron recovery was66.99%in iron concentrate under air cooling. And in magnetic tailings rare earth grade was7.41%and rare earth recovery was56.55%. After magnetic se-paration iron grade was48.65%and iron recovery was77.48%in iron concentrate under wa-ter cooling. And in magnetic tailings rare earth grade was9.13%and rare earth recovery was82.70%. The optimal magnetic intensity was233.33kA/m, under which it could obtain iron grade of51.41%, iron recovery of68.45%, rare earth grade of7.85%, rare earth recovery of87.61%. Under proper conditions Fe2O3in rare earth tailings would transform to Fe3O4. However, inadequate roasting conditions and the re-oxidation of Fe3O4both would result in the existence of Fe2O3. And Fe2SiO4would form when the reduction process is excessive. The above results show that magnetization roast-weak magnetic separation can separate out iron efficiently and achieve the separation of iron and rare earth effectively.