Experimental Study On Optimization Of Blast Furnace Slag System For Smelting Vanadia-Titania Magnetite With High Chromia

Vanadia-titania magnetite is an important mineral resource that is the raw material of ironmaking, Vanadia extraction and manufacture of metal titanium and titania dioxide, and it has high utilization value. Since the grade of China’s iron ore is low, the iron ores of iron and steel enterprises are mostly imported. Domestic and foreign scholars have been doing a lot of fruitful researches on the blast furnace smelting vanadia-titania magnetite for50years, but there is still not a formed complete theoretical system on smelting the imported vanadia-titania magnetite. However, slag system is one of the four basic systems of blast furnace, and it has important effects on the production of blast furnace, quality of pig iron, coke rate, costing of pig iron, prograde motion of blast furnace and the life of blast furnace. There is a steel company, which introduces the vanadia-titania magnetite from neighboring Russia, and this kind of vanadia-titania magnetite has characteristics of high vanadia and high chromia. And the researches of the blast furnace slag metallurgical properties produced by such ore have never been done in China.From the field reality, this thesis optimized on-site slag system and analyzed the effects on slag system metallurgical properties by the factors of alkalinity, MgO content, TiO2content, Al2O3content by analyzing pure chemical reagents as the test materials, and by matching the slag, pre-melting, and measuring viscosity of slag. Besides, it also analyzed the influence law of slag system metallurgical properties produced by vanadia and chromia.At last, we reached the following research results:(1) The optimal slag system was arrived by orthogonal test weighted scoring method:Alkalinity1.15,10%of MgO content,8%of TiO2content,15%of Al2O3content. Besides, the influence of comprehensive index of the slag system respectively is the content of Al2O3, MgO content, TiO2content and alkalinity.(2) The influence of single factor changes on the metallurgical properties of the slag system:With the increase of alkalinity, temperature of slag melting increases, and the initial viscosity and high-temperature viscosity increases and then decreases; with the increasing of MgO content, temperature of slag melting decreases and then increases, and the initial viscosity decreases, and high-temperature viscosity increases and then decreases; with the increasing of Al2O3content, temperature of slag melting increases, and initial viscosity and high-temperature viscosity decreases and then increases; with the increasing of TiO2content, temperature of slag melting increases, and initial viscosity and high-temperature viscosity decreases.(3) The influence of vanadia and chromia changes on the metallurgical properties of the slag system:Slag melting temperature and initial viscosity both decrease slightly with increasing V2O5content by adding V2O5content from1%to3%; slag melting temperature decrease slightly with increasing Cr2O3content, but initial viscosity increase slightly by adding Cr2O3content from1%to3%. Slag high-temperature viscosity basicly unchanged with increasing both V2O5and Cr2O3content from1%to3%.