采用化学分析及ICP,XRF,XRD,SEM-EDS,FESEM等系统地分析了太钢、宝钢不锈钢粉尘的化学成分、物相组成及形貌特征等,并利用FactSage热力学软件计算了不同条件下Cr-Fe-C-O,Ni-Fe-C-O等体系的优势区图,结合不锈钢冶炼条件,理论上证明Cr和Ni在不锈钢粉尘中分别以FeCr2O4和Fe2NiO4形式存在.热力学计算结果表明,对于常见的4种还原剂(C粉、FeSi和SiC、铁液中[C]),FeCr2O4中的Cr较Cr2O3中更易被还原,且1500℃以下各还原剂还原能力为:FeSi〉SiC〉铁液中[C]〉C粉;而1500℃以上为铁液中[C]〉FeSi〉C粉〉SiC.对于Ni的还原,以FeSi和SiC为还原剂时,Fe2NiO4会优先于NiO被还原;而当采用C粉或铁液中[C]作为还原剂时,NiO优先Fe2NiO4被还原.初步探讨了以Fe基合金形式分离回收不锈钢粉尘中的Cr和Ni资源的工艺思路的可行性.
Chemical compositions,substantial phases,and microscopic morphology of stainless steel dust from TISCO and BaoSteel were analyzed by using several methods,chemical analysis,ICP,XRF,XRD,SEM-EDS and FESEM.Meanwhile,the predominance diagrams of Cr-Fe-C-O and Ni-Fe-C-O systems under various conditions were simulated by using FactSage software.Combining the conditions of stainless steel-making process,it is suggested that in stainless steel dust Cr and Ni exist in the forms of FeCr2O4 and Fe2NiO4,respectively.Furthermore,thermodynamic predictions show that for the four kinds of reduction reagents,C powder,[C] in molten iron,SiC and FeSi,FeCr2O4 is reduced to metallic Cr prior to Cr2O3,and below 1500℃ the reduction ability of these four reagents has the following order:FeSi SiC [C] in molten iron C powder,while above 1500℃,it becomes:[C] FeSi C powder SiC.And for the reduction of Ni,in the cases of FeSi and SiC as reagents,Fe2NiO4 is reduced prior to NiO,while in the cases of [C] and C powder used,the reduction of NiO is easier.Finally,the recovery feasibility of Cr and Ni from stainless steel dust in the form of ferroalloys is discussed.