Study On Technology Of Dust Removal In Steel Smelting As Raw Material

There are a lot of valuable metal components（mainly iron and zinc）in the bag dust of blast furnace,the basic condition of resource utilization is to separate the zinc and iron components.The separation of iron and zinc from dust was studied in the following three aspects.Firstly,the mineral occurrence state of Zn was determined,the difference of wettability between it and gangue mineral was analyzed,and the technological parameters of the sulfide-xanthate flotation were optimized;Secondly,the thermodynamic characteristics of selective dissolution reaction of FeCl₃·6H₂O were analyzed to determine the optimal operating parameters in the closed system with FeCl₃·6H₂O;Finally,the hydrothermal reaction of ammonium ferric sulfate dodecahydrate（NH₄Fe（SO₄）₂·12H₂O）for the selective dissolution of zinc minerals and the separation of iron and zinc elements were studied.The results of chemical phase and mineral analysis of raw materials showed that Zn O was the main element of Zn in the dust,and its distribution ratio in the total zinc content was 76.21.Zinc ferrite（Zn O·Fe₂O₃）was the second,accounting for 12.36 of the total zinc content.Iron-bearing minerals mainly include pseudomorphic hematite（Fe₂O₃）and magnetite（Fe₃O₄）.The difference of contact Angle between zinc oxide and gangue mineral increases with the increase of sodium sulfide.Therefore,it is suitable to extract zinc by the sulfide-xanthate flotation.The results of flotation experiments showed that the optimum flotation parameters were 3 kg/t sodium sulfide,1 kg/t sodium silicate,2 kg/t sodium hexametaphosphate,500 g/t copper sulfate,and 800 g/t butyl xanthate.The grade of zinc concentrate was 13.44%（raw zinc was 6.39%,iron was 26.72%）,iron was 12.16%,the grade of zinc and iron in tailings was 0.21%and 56.86%respectively.Thermodynamic calculations showed that the dissolved equilibrium p H of Zn O and Zn Fe₂O₄ are higher than those of Fe₂O₃ in the closed system,which is suitable for the selective dissolution of zinc by ferric chloride hexahydrate（FeCl₃·6H₂O）.The experimental results showed that the optimal process parameters mass ratio of materials to reagents were 1:2,reaction temperature was 190℃,and reaction time was 14 h.Under this condition,the Zn leaching rate was 99.56%,the TFe content in the leaching residue was 48.22%,and the Zn content was as low as 0.034%.The results of selective dissolution of zinc-containing minerals with ammonium ferric sulfate dodecahydrate（NH₄Fe（SO₄）₂·12H₂O）showed that the optimal process parameters were the mass ratio of materials to reagents were 7:12,reaction temperature was 190℃,and reaction time was 12 h.The leaching rate of Zn was 99.26%and the leaching rate of Fe was 2.15%in one step.The leaching residue TFe content was 48.65%and Zn content was 0.11%.