锰铁合金制备磷酸锰铁溶液OA

For the resource utilization of ferromanganese alloy,a phosphoric acid leaching method was proposed to prepare the precursor solution(manganese-iron phosphate solution)for lithium battery cathode materials.Through single-factor and orthogonal experiments,the optimal conditions were determined as follows:an acid excess coefficient of 1.2,a liquid-to-solid ratio of 11∶1,a temperature of 70℃,and a time of 1 h.Under these conditions,the leaching rates of Mn and Fe reached 97.42%and 92.81%,respectively.The impurity content in the purified solution met industrial standards.Thermodynamic analysis confirmed the spontaneous reaction characteristics(ΔG<-40 kJ/mol),and the E-pH diagram of the Mn-Fe-H3PO4 system was constructed.It revealed the critical conditions for the stable existence of Mn2+at pH<2.20 and for the precipitation of Fe3+at pH>0.56.Kinetic studies indicated that the leaching process followed the unreacted core model,with activation energies of 44.47 kJ/mol for Mn and 48.08 kJ/mol for Fe,suggesting a chemical reaction-controlled mechanism.This work provided a new low-cost approach for the preparation of lithium manganese iron phosphate(LMFP).