Selective Chlorinated Extraction of Iron and Manganese from Vanadium Slag and Their Application to Hydrothermal Synthesis of MnFe2O4

Several valuable elements, including V, Cr, Fe, Mn, and Ti, exist in vanadium slags. In this paper, an innovative way to extract Fe and Mn selectively and destroy the typical encompassed structure with NH4CI has been proposed. Fe and Mn are then used to synthesize MnFe2O4, and the residue is an enriched Cr V Ti O mixture. Moreover, the chlorination agent NH4CI can be recycled in this process. Vanadium slag was mixed with various amounts of NH4Cl and NaCI in a temperature range from 300 degrees C to 900 degrees C for 1 to 8 h. The optimal conditions for the chlorination of Mn and Fe are NH4Cl slag mass ratio of 2:1, NaCl NH4Cl mass ratio of 0.308:1, 800 degrees C and 4 h. The manganese and iron chlorination ratio can be reached at 95% and 72%, respectively. The presence of NaCI can enhance the chlorination rate of manganese and iron. Manganese ferrite powders were prepared via hydrothermal treatment of iron and manganese in the leaching solution at a temperature of 140-200 degrees C. The synthesized MnFe2O4 exhibits high saturation magnetization (Ms, 55.85 emu/g) and low coercivity (Hc, 38.4 Oe). The possible mechanisms involved in these findings are explored.