Study On Preparation Of Fe-Mn Alloy From Wolframite Leaching Residue By High Temperature Carbon Reduction

The resource utilization and harmless disposal of tungsten leaching residue is a difficult problem in tungsten smelting industry and environmental protection field.At present,the large amount of wolframite leaching residue contains arsenic and lead and other toxic elements,which seriously restricts the development of tungsten smelting enterprises.In view of the characteristics of large amount of Fe-Mn and small amount of valuable metals such as tungsten,tin and niobium in wolframite leaching residue a new idea of preparing Fe-Mn alloy with wolframite leaching residue by high temperature carbon reduction was put forward to realize the recovery of valuable metals such as Fe,Mn,tungsten,tin and niobium in the form of alloy and volatilization separation of arsenic and lead.The innovative results of this study are as follows:The phase composition of wolframite leaching residue was investigated.By MLA,XRD characterization analysis,it shows that alkali cooking black tungsten slag in the main phase is-colloidal silica,iron oxide manganese iron oxide-silicone gel,in addition to containing undissolved Mn Fe₂O₄residual minerals,calcium carbonate,fine crystal,including the price element,niobium tungsten,tin,lead,bismuth,arsenic are mainly distributed in iron oxide manganese-silicone gel,ferric oxide-silica gel in the body.The effects of reducing agent dosage,temperature,time and co-solvent on the preparation of Fe-Mn alloy by high temperature carbon reduction from alkali-boiled wolftungsten slag were elucidated.With the increase of reducing agent dosage,the alloying rate of Fe,W and Sn changed little,but the alloying rate of Mn increased gradually.With the increase of temperature,the alloying rate of Fe,W and Sn increased firstly and then remained unchanged,while the alloying rate of Nb and Mn increased gradually.With the prolonging of smelting time,the alloying rate of Fe,Mn,W,Sn and Nb increases at first and then tends to be stable.The co-solvents Si O₂ and Al₂O₃ lead to the decrease of alloying rate,while Ca O is beneficial to the increase of alloying rate.Under the optimal conditions of reducing agent dosage of 16%,melting temperature of 1550?,melting time of 120 min and Ca O dosage of 15%,the alloying rates of Fe,Mn,W and Nb are 97.07%,62.07%,99.62%and 95.39%,respectively,while the contents of As,Pb and Bi in the alloy are all lower than 0.2%.The phase transition rule of Fe-Mn alloy prepared from a wolframite leaching residue by carbon reduction was revealed.The phase,surface chemical state and morphology analysis of the reduction produc ts at high temperature show that iron and manganese oxides are reduced to Fe₃C and Mn O step by step.At 900?,Mn⁴⁺is completely reacted,and Mn³⁺continues to be reduced to Mn²⁺.At 1200?,the reduction products mainly consist of Mn²⁺,and some incomplete Mn³⁺exists.Increasing the temperature is conducive to the process of reduction reaction.At low temperature,metal particles begin to gather,join and grow from the surface of wolframite leaching residue,the edge of hole and the void.At high temperature,Burdor reaction occurs to produce CO,and metal particles gather,join and grow in the central area.