Study Of Raw Fuel Characteristics And Optimization Of An Iron Plant In Northeast China

With the rising prices of raw fuels such as coking coal,coke and iron ore and the continuous advancement of ironmaking technology in recent years,reducing the cost of iron has become a major means of improving the competitiveness of ironworks.To accommodate this adjustment,ironmaking technology,represented by a northeastern iron and steel company,has also undergone significant changes,particularly the extensive use of tamped coke and PB lump ore in its blast furnace raw fuels.The change in raw fuel structure poses new challenges to the stable smooth operation of the blast furnace.In this paper,the properties of pounded coke are investigated using the equal dissolution rate method for the raw fuel conditions of an ironmaking plant in Northeast China,and the influence law of the reduction reaction of PB lump ore is studied by means of kinetic modelling and laboratory experiments to optimise the furnace charge structure.The main research contents and conclusions of this paper are as follows.(1)Among the four types of mash coke,mash coke D has the highest level of alkali catalysis,mash coke A is second,mash coke C is second and mash coke B has the lowest level of alkali catalysis.Carbon microcrystals developed at the best level for tampered coke A and tampered coke C,followed by tampered coke D and lower for tampered coke B.The OTI index was highest for tampered coke C,decreasing in order for tampered coke B and tampered coke A and lowest for tampered coke D.The heat values of the four types of pounded coke from highest to lowest are Pounded Coke A,Pounded Coke D,Pounded Coke C and Pounded Coke B.(2)Experimenting with the comprehensive thermal properties of coke,the isothermal isothermal dissolution loss rate method can better distinguish the superiority and inferiority of coke performance at different temperatures.Pounded coke A has the best strength,pounded coke D is the second strongest,pounded coke C is the second strongest and pounded coke B is the worst,but it should be noted that in the high temperature section(1300°C),the strength of pounded coke C has a tendency to decrease significantly.(3)The soft melt drip performance of the three sinter basically meets the requirements of blast furnace smelting,but the melt drip interval is slightly wider for all of them.The soft melt drip performance of pellet ore is better,while PB lump ore has a very low softening onset temperature,a wide softening and melt drip interval and a very large pressure difference,indicating that it is very unfavourable to the permeability of the blast furnace soft melt drip zone.Both the kinetic equations of the unreacted nucleus model and the Arrhenius diagram were calculated to show that the reduction process of PB lump ore is controlled by a mixture of interfacial chemistry and gas internal diffusion,with the interfacial chemistry being the limiting link.(4)As the proportion of PB lump ore increases,the reduction of the mixed ore decreases,and the reduction of PB lump ore decreases more rapidly,with the proportion of PB lump ore in the mixed iron-bearing charge up to 20%.According to the post-reduction microstructure of sinter,pellet ore and lump ore,it can be found that:the reduction of iron ore edges are all relatively adequate,mainly including metallic iron and silicate;the reduction in the centre of iron ore determines the metallurgical performance of iron ore,and the proportion of metallic iron in the centre of iron ore is from lump ore,sinter and pellet in descending order.