Intergrative Utilization Of Desulphurization And Skimming Slag In Hot Metal Pretreatment From Ansteel

It is importance to iron and steel enterpraise that quantitative reduction, resources and high-value intergrative utilization of steel slag. As an iron and steel resource, desulfirization and skimming slag is stacked in slag yards temporarily owing to the shortage of effective utilization technologies, which results in iron waste, land occupancy and environment pollution.Integrative utilization of desulfization and skimming slag, from No.1steel-making mill of Ansteel Group, was investigated. Basic on the detailed research of process mineralogy, iron is to be recycled by mineral processing method to obtain suitable recycling process and operation parameters, and the utilization technologies of recyling iron and slag tailings were studied. Hydrating and hardening mechanisms of slag tailings concrete was explained by means of several detection measures.Composition characteristics of desulfization and skimming slag were studied by means of chemical analysis, optical microscope, X-ray Diffraction and Scanning Electron Microscope. It was shown that iron of54.18%was the value recycling element, sulfur of1.01%was the harmful element, main pahses were metal iron, magnetite, ferrite and silicate, subordination plases were wustite, aluminate, aluminosilicate and slaked lime, total iron distributed mainly in coarse fraction and sulfur distributed in coarse and fine fraction.Iron-riched product Ⅰ (+2mm) and iron-riched product Ⅱ (-2mm+0.3mm) were obtained after desulfurization and skimming slag was crushed and screened, and four separation experiments, including single gravity separation, single magnetic separation, gravity-magnetic separation and magnetic-gravity separation, were undertaken to the-0.3mm part. The gravity-magnetic separation method were selected and suitable operation parameters were got. The iron concentrate as-concentrated was named as iron-riched product III, and the gravity tailing and the magnetic tailing were mixed as desulphurization and skimming slag tailing. Iron-riched product I and II with iron grades of more than90%, could be put directly into electric cooker for steel-making, Iron-riched product III could be introduced into blast furnace, and the slag tailing with component being similar to cement could be substitute partially for cement clinker.Three methods of stirring at20℃in water, stirring at90℃in water and mill grinding were to eliminate free lime (f-CaO) in tailing. The effects arranged by order was mill grinding, stirring at90℃in water and stirring at20℃. The content of f-CaO was2.96%at mill grinding30minutes.Desulphurization and skimming slag tailing superfine powder were prepared by tumbling mill and stirred mill, and the effects of ball to power ratio, slurry concentration and grinding time were investigated. The superfine slag tailing powder with specific surface area of569.5m2/kg, at ball to power ratio of1.0, grinding concentration of60%, grinding time of30min in tumbing mill was selected as an admixture of cement concrete.The effects of slag tailing powder mixing on standard consistency water demand, initial and final setting time, boiling stability, compress strength and bending strength at3and28days, fluidity and erosion resistence of cement were tested, and suitable mixing amount of0to50%were achieved.The performances of slag tailing cement concrete were observed, new mixing workability, compress strength and elastic modulus at certain age were used for evaluating the mechanical properties. While freezing thawing resistence and carbonation resistence evaluated the durability. Results showed that suitable mixing amount of slag tailing was0to30%, and the slag tailing mixing could decrease concrete slump. Concrete of C20to C40could be prepared, and whose freezing thawing resistence could meet the requirement of D50.The hydration products components and microstructure were characterizted by SEM-EDS and XRD. The dense regularity of slag tailing particles and cement particles was analyzed, and the hydration mechanism was explained by combining the microproperties and manificent characteristic.The detailed elimatation experiments of free CaO and separate recycling of different products were innovative. The intergrative utilizations of desulphurization and skimming slag, the process mineralogy research, iron recycling and slag tailing being admixed into cement, were realized. And it was of important guiding meaning to the slag resource exploitation.