Migration Behavior Of Slag Component During Iron-extraction Process By Smelting Reduction Of Modified Nickel Slag

Nickel slag produced from the nickel smelter has a higher iron content,nickel slag can be recycled as a potential secondary resource.Iron existance in nickel slag is mainly fayalite,which bears a high stabilization and induces a poor reducibility of iron.Therefore,it is proposed that nickel slag should be modified by converter slag with higher basicity and then reduced by aluminium dross.The process can not only increase the activity of 'FeO' in molten slag,but also realize the purpose of "waste to resource".In this work,the activity model of CaO-SiO2-Al2O3-'FeO'-MgO-P2O5-MnO-Cu2O system during the reduction process was constructed based on the molecular ion coexistence theory.The evolution of the component activities was studied to lay a foundation for the smelting reduction process from nickel slag.On this basis,the migration behavior of slag components during iron-exaction process from modified nickel slag by alumunm dross.The following conclusions can be drawn:(1)For the CaO-SiO2-Al2O3-'FeO'-MgO-P2O5-MnO-Cu2O system,the activities of CaO,Al2O3,MnO,3CaO-P2O5,and Cu2O all increased with an increasing basicity under the same temperature,but that of SiO2 decreased.The activity of‘FeO'(a('FeO'))showed a maximum at the basicity of 1.00,which was determined as the basicity of modified slag.(2)When the basicity of modified slag is constant,the activities of CaO,Al2O3,SiO2,'FeO',MnO and Cu2O did not change significantly with the increasing slag temperature.However,the activity of 3CaO·P2O5(a(3CaO·P2O5))decreases gradually.(3)Effects of baisicity of modified slag and the reduction degree of‘FeO'on investigated component activities showed that the maximum of a('FeO')of 0.66 was obtained under the basicity of 1.00 at 1773 K.a(3CaO·P2O5)increased either with the increase of‘FeO'reduction degree or with the basicity of modified slag.The change of activity of MnO(a(MnO))was not siginicant with the reduction degree of 'FeO' but it increased gradually with the increasing basicity of modified slag.(4)Effect of Al/'FeO' on the migration behavior of slag components indicated that the reduction sequence was Cu2O?'FeO'?3CaO·P2O5?MnO?SiO2 during the smelting reduction process.With the increasing Al/'FeO' ratio from 0.40 to 0.71,Cu2O was reduced accompanied with the reduction of‘FeO'.3CaO·P2O5 was reduced after the Al/'FeO' ratio lager thatn 0.67.MnO was finally reduced.(5)The reduction holding time and basicity of modified slag had a less impact on the migration behavior of slag components.3CaO·P2O5 was reduced prior to the MnO under different conditions.In additon,the diffusion and migration of reduced iron were more enough at the basicity of 1.00,which was helpful to the separation from slag.