Investigations On The Fundamental Characteristics And Efficient Dezincification Of Zn-bearing Blast Furnace Dust

Blast furnace dust is the product captured by the gas dedusting system during the blast furnace ironmaking process and is one of the major solid wastes of iron and steel enterprises.Chinese iron and steel enterprises produce a large amount of blast furnace dust every year.Among them,there are beneficial components such as iron and carbon,making blast furnace dust a valuable secondary resource.As people attach great importance to the environment and the reuse of waste,the reuse of blast furnace dust as a secondary resource has attracted more and more attention.The use of blast furnace dust as sinter is a simple method of recycling.However,the direct addition of zinc-bearing blast furnace dust to the sintering material will enrich the zinc in the blast furnace and seriously affect the blast furnace production.At present,The treatment methods mainly include beneficiation,hydrometallurgy and pyrometallurgy.In this study,on-site sampling of blast furnace dust from a steel plant in Shanxi Province was carried out.ICP-AES,XRD,SEM-EDS,and DTA-TG were used to detect and analyze the characteristics of zinc-bearing blast furnace dust.High-temperature roasting was used to study the effects of temperature on the phase composition,micro-morphology,and elemental content.The hydrometallurgy process is used to remove the zinc from the blast furnace dust.The feasibility of leaching was analyzed by E-pH plot,and the leaching effect of common leaching agents was compared.After selecting the appropriate leaching agent,the optimum leaching conditions were determined.XRD and SEM-EDS analyses were performed on the leaching residue.Discussed the effect of multiple leaching on leaching rate.The leaching restriction was found by kinetic analysis and the apparent activation energy was calculated.Research indicates:?1?The particle size and element content of blast furnace dust are related to each other.Zn and Fe are mainly distributed in the finer particles,and C is mainly distributed in the coarser particles.?2?The Fe in blast furnace dust is in the form of hematite?Fe₂O₃?and magnetite?Fe₃O₄?.The form of Zn in the blast furnace dust is complex,and some of the Zn is present in the form of zinc ferrite?ZnFe₂O₄?.?3?With the increase of roasting temperature,some unstable amorphous substances in the blast furnace dust are reduced,the proportion of stable silicates increases,and the particles gradually become larger,and there is a clear tendency of agglomerating.?4?After roasting for 1h at 1200°C,the content of Fe increased from 39.1%to 45.3%,the content of Zn decreased from 1.7%to 0.9%,and the removal rate of zinc was 52.9%,the content of C decreased from 24.9%to 6.7%.?5?After comparing the leaching effects of different leaching agents on Zn and Fe in blast furnace dust,sulfuric acid was selected as the best leaching agent when the leaching conditions were sulfuric acid concentration 1mol/L,the solid-liquid ratio was 1:8,the temperature was 25°C,and the stirring speed was130r/min.When the leaching time was 300 min,the leaching rate of zinc was90%,and the leaching rate of Fe was 23%.?6?Under the leaching conditions of 25°C,50°C and 80°C,the leaching restriction was internal diffusion and the apparent activation energy was8.14kJ/mol.?7?The Fe in the leaching residue is in the form of hematite?Fe₂O₃?,magnetite?Fe₃O₄?and iron oxyhydroxide?FeO·OH?,and zinc is present in the form of zinc ferrite?ZnFe₂O₄?.?8?The use of leaching agent for many times reduced the leaching rates of Zn and Fe.The leaching rate of Zn after three times of anti-leaching tends to be flat and the leaching rate is about 45%.