Research On Mn-Al Master Alloy Prepared From Manganese Ore

Manganese resource is stragegic and scarce for our country,and our county is thelargest manganese ores and production base.The western regions are famous as itsabundant manganese resources.Energy consumption per unit products andenvironmental index have large gap between our county and the world-class level.Products with high additional value and new materials can’t meet the need of nationaleconomy.In order to meet this goal,it is important to take actions to study the preparingtechnology and new materials。In this paper, MnAl master alloy is prepared by Self-propagting Aluminumreduction process in which Mn₂O₃,Mn₃O₄（prepared in the heating system of600C and900C by manganese dioxide respectively） and CaO were taken as raw materials and Alas a reductive agent.The best preparation parameters such as the aluminum amount,theparticle size of Al powder,the additive amount,the calcium fluoride amount have beendetermined for the Mn content and the Mn yield rate by orthogonal experiment.Andthen using reduction roasting leaching process to remove the impurity.The keyprocessing conditions such as acid concentration,leaching time, leaching temperature,ore slurry ratio have been studied for the leaching ratio of manganese in ores bysingle-factor test. Thirdly,the manganese tetroxide was prepared by adding ammonia tothe leaching solution,and MnAl master alloy was prepared by SHS. Finally,MnAlmaster alloy were applied to produce AZ91magnesium alloy.The main resuls showthat：①Based on thermodynamic calculation and analysis, including the calculation ofadiabatic temperature and the free entropy.The adiabatic temperature was3160K,andthe feasibility of the SHS reaction was determined consequently.②The ratio of Mn₃O₄and Mn₂O₃is3︰2，and CaF₂account for60%of theadditives，the content and yield rate were the best by the single factor experiment. Theparticle size of Al powder is109-150μm,excessive30%Al,the amount of additiveaccount for the amount of Al is30%,CaF₂account for the additive is60%.③The best optimum leaching condition is that acid concentration0.8mol/L，andore slurry ratio1︰25,leaching temperature60⁷0℃,leaching time1.5h.④Add ammonia to manganese sulfate solution，and generate precipitation，wecan get pure manganese tetroxide by filtering and drying.And then produce the manganese content of79.22%MnAl master alloy by SHS.⑤AZ91magnesium alloy was prepared by AlMn15,AlMn90，AlMn85andALMn80master alloy.AlMn90and AlMn80were prepared by SHS using analyticalpure manganese oxide，while AlMn80master alloy was prepared by SHS using Mnores.Chemical composition and microstructure of AZ91alloy met the relatedstandards,while the mechanical properties can not meet the national standard.In this paper,the process of preparing MnAl master alloy by SHS have someadvantages,For example：it is simple and low cost;we need not too much investment inequipments;short process;and not need external heat source,the energy released from thereaction can maintain the process of the reaction.it is very beneficial for our society andeconomy.