Experimental Study On Improving Low Temperature Reduction Degradation Property Of Sinter In An Iron And Steel Enterprise

As one of the most important iron-bearing materials for BF ironmaking,sinter quality and metallurgical properties play very important role in the blast furnace smelting index and the economic cost control in the whole steel production process.Therefore,it is an inevitable choice for the steel enterprises to reduce production cost,increase economic benefits and win in the fierce competition by reasonably utilizing the raw materials for sintering to produce high quality sinter.In view of the problem of low temperature reduction degradation index of sinter in a steel enterprise,this paper is commissioned by the steel enterprises to improve the low temperature reduction degradation index of sinter by 5%field sintering ore,providing technical support and theoretical guidance for field sintering production.Therefore,based on the data of production and sintering related materials in the field,this paper first analyzed the causes of low temperature reduction degradation of sinter produced in the field by means of chemical analysis and detection of ore-phase.Sintering cup tests and sinter metallurgy property testing device are applied to propose preliminary improvement measures from the aspects of quick lime ratio,content of the South Africa fine powder and content of powder burning.Secondly,this paper systematically investigated the influence of optimization ore matching and sintering process parameters on sintering index,including law of sinter yield,vertical sintering speed,drum index and RDI+3.15,aiming to aquire the best sintering optimization ore matching program and sintering process parameters.Through the research,the main conclusions are as follows:(1)The low temperature reduction degradation of sinter in the iron and steel enterprises are mainly caused by the insufficient proportion of quick lime,the high content of harmful impurities TiO2,the high proportion of powder burning,the coarse granularity of raw materials and the unreasonable structure of ore matching for sintering.(2)After adjusting the ratio of quick lime to 4.5%,the content of South Africa fine powder to O,the ratio of powder burning to 6%,the content of calcium ferrite in the binder phase increased and the content of silicate decreased.The low temperature reduction degradation property of sinter was preliminarily improved.(3)The sinter yield,vertical sintering speed,drum index and RDI+3.15 reach better value with a proportion of self-produced concentrate of 20%(5%and 15%respectively in Soyen and Yushan),a proportion of Baka of 15%,a proportion of Newman of 30%,a proportion of one steel powder of 1.76%,a proportion of ludwigite of 2%,which is a reasonable ore blending scheme of sintering.(4)With the increase of basicity,the sinter yield,drum index first increased and then decreased,the vertical sintering speed and low temperature reduction degradation tended to increase.The content of hematite gradually decreased.The content of calcium ferrite in the binder phase gradually increased.The best basicity was 2.1.Under this condition,the sinter yield was 76.53%,the vertical sintering speed was 23.01 mm/min,the drum index was 65.65%,and the RDI+3.15 was 68.89%.(5)With the increase of MgO content,the sinter yield kept stable.The vertical sintering speed,drum index and low temperature reduction degradation property showed a gradual downward trend.With Mg2+dissolving into the Fe3O4 lattice,the conversion of magnetite to hematite was inhibites effectively.The content of silicate increased in the binder phase and the best MgO content was 1.9%.Under this condition,the sinter yield was 81.52%,the vertical sintering speed was 21.47 mm/min,the drum index was 67.43%,and the RDI+3.15 was 62.38%.