Experimental Study On Acid Pellet Sintering Process Of Jiu Quan Steel

With the rapid development of the steel industry of China,the iron ore supply fails to meet the demands,many domestic steel companies in order to reduce the cost of sintering and start using the surrounding self-produced iron ore concentrate.Iron ore with different properties quality has been used in China steel enterprise by a series of beneficiation process.Which result in the unstable problems,such as,the gas permeability in the sintering process become worse,low product yield,poor quality and high energy consumption.Acid pellet sintering can not only adapt to the refining raw materials,having a better permeability and improving sinter quality,but also can replace the expensively acid pellet of blast furnace burden structure and cost reduction.In this paper,the self-produced raw materials used in Jiuquan steel and the surrounding iron ore resources were used as research objects to study the iron ore pelletizability.Based on that to study the influence of adding fuel separately,pellet size and varying proportions of iron ore on the sinter technology targets,analyzing the relationship between the mineral composition,structure and the quality of sinter.In addition,the low basicity on sintering mineralization characteristics was studied with laboratory briquetting.Results are as follows:With the continuous extension of the pellet,the average particle size of the pellet gradually increased,balling for 10 min,the drop strength reached the maximum,the compressive strength is relatively high.When the water content of ball increased from 8% to 9.5%,the ball was increasing,the drop strength was approximately linear and the compressive strength was higher than 9.0%.The disc speed increased from 15 r/min to 24 r/min,the average particle size of the pellet increased first and then decreased,the overall strength of the 3~5mm ball drop became larger,the particle size and composition of the pellet were better at the speed of 18 r/min.When the pellet size,ore blending ratio and basicity are the same,the yield of the sinter,tumbler strength and the low temperature reduction powdering index were improved with the increase of internal proportion of fuel from 0% to 30%,while the vertical sintering speed and sinter ore grade changed little,more than 30% later,the sintering of the technical indicators have appeared to varying degrees of reduction.When the proportion of fuel 30%,the apparent initial softening temperature and the softening range of sinter is better,more than 40 mm sintered ore more,and less than 5mm relatively small.When the ratio of fuel is 30%,the softening property of sinter is better than that of 40 mm,but less than 5mm.The content of FeO in sintered ore is generally high and the reducibility is low;the pellet size have an effect on sintering indexes significantly,When the particle size of 3~10mm is about 90%,the sintering strength,vertical sintering speed and yield are generally better;Increasing the proportion of Bo lun concentrate can improve the physical properties of sintered ore appropriately.Under the current raw material conditions,the appropriate comprehensive concentrate powder is 80%,Bo lun ore ratio of 20%;It can be seen that the mineral composition of the acid pellets is mainly composed of magnetite and fayalite by analyzing the pellets,and the structure is dense,which improves the sinter strength.The compressive strength of the sintered product increases with the increase of the calcination time,and then decreases with the increase of the calcination temperature,then decreases with the increase of alkalinity.The main phases of the sintered products are hematite and magnetite,accompanied a small amount of fayalite bound phase and silica.The sintering products are mainly composed of hematite recrystallization,liquid phase fayalite.