The Process Technology Research Of Long Life Refractories For Large Blast Furnace Casthouse

At present,the utilization coefficient of domestic small blast furnace is low,and the pollution is serious.In order to comply with the national environmental protection industry policy,small blast furnace is gradually eliminated,and the iron making blast furnace is developing to large-scale,energy-saving and automation.The daily iron output of large blast furnace(>3800m~3)is more than 10000 tons,the hot metal flow rate is fast,the flow rate is large,and the scouring and erosion to the tapping yard are also increased.Therefore,the original refractory for small blast furnace(<3200m~3)is no longer suitable,and a long life refractory suitable for large blast furnace is urgently needed.In this paper,the effects of different corundum aggregate,silicon carbide particle size,composite carbon source,metal silicon powder,composite binder and micron composite powder on the performance of iron channel castables were studied.The erosion rate of different parts of iron channel was obtained by measuring the erosion situation of each part of iron channel on site,and the iron channel was re zoned to balance Provide technical support for material and standard construction.Through the experimental results,the following conclusions are drawn.(1)By comparing the index performance of three kinds of fused corundum,fused brown corundum is suitable for large particle aggregate of iron channel castables,fused dense corundum is second,fused white corundum is not generally used for large particle aggregate of iron channel castables.Considering the specific use conditions and cost,88 bauxite can be partially used.(2)Reasonable Si C particle size is helpful to improve the fluidity,overall strength and slag resistance of the castable.The addition of silicon carbide is generally between 12-30%.According to the different zones of iron groove,the silicon carbide content of iron groove castable for slag line is generally more than25%,and that of iron groove castable for iron wire is generally 12%.(3)The results show that the composite carbon has better slag resistance because of the use of some flake graphite with higher fixed carbon content.At higher temperature,the carbon loss is reduced and the carbon residue in the material is increased,which is helpful to produce more Si C reinforced structure and improve the high temperature strength.The wettability with the melt becomes worse,showing better slag resistance.(4)Metal silicon is helpful to improve the slag resistance of iron channel material,mainly in two aspects.One is that as an antioxidant,it can protect the carbon in castable and make it play a lasting role;on the other hand,the liquid phase produced by oxidation of metal silicon plays a protective role.The experimental data show that the appropriate amount of silicon is about 2%.(5)Through the use of high-efficiency enhanced binder,the introduction of calcium oxide can be reduced,and the amount of low melting point phase at high temperature can be reduced.At the same time,the strength of the material remains stable during the whole heating process,and the structural strength of the material is improved.(6)The addition of micron composite powder can better fill the micro pores in the material.Because the micron composite powder has higher specific surface area and activity,it is easier to be fused and sintered at high temperature,and the matrix part is easier to be transformed into mullite phase,which improves the bonding strength between matrix and aggregate,and improves the compactness and structural strength of the material.(7)The main ditch of the cast iron yard is divided into different zones,and the erosion of the working layer of the main ditch caused by the mixture of iron slag is clarified.Reasonable zoning materials and improved construction can prolong the service life of the main channel and reduce the cost of refractory materials.The improvement of the main ditch partition method can provide technical support for the later maintenance of the slag outlet and the tap hole of the cast iron ditch,and can effectively avoid the safety and quality accidents of slag passing through the slag ditch or slag passing through the iron ditch.(8)The proportioning and site construction scheme of ASC long-life castables were optimized and adjusted.The site construction tests were carried out at 5 and 7tapping yards of 2×5100 m~3 blast furnace in Rizhao fine steel base of Shandong Iron and steel group.The results show that the primary iron flux of 5 and 7 tapping yards is211961 tons and 210784 tons respectively,which are far higher than the 180 thousand tons required by the steel plant,It is proved that the overall performance design,product preparation and field application of ASC castable are successful.