Study On Performance Of Environmental-friendly Tap-hole Clay For Largescale Blast Furnace

Tap-hole clay is a kind of plastic refractory which is specially designed to block the tapping hole of blast furnace.According to the actual condition of blast furnace,good plasticity,proper sintering property,appropriate strength,good physical and chemical corrosion resistance are very important to the longevity of blast furnace.With the improvement of national laws and regulations and people's environmental-friendly awareness,the study of environmental-friendly tap-hole clay for blast furnace is of great practical significance.At present,coal tar,resin and asphalt are commonly used as binders in tap-hole clay.These traditional binders could provide good plasticity and durable performance for tap-hole clay.However,they always contain a variety of polycyclic aromatic hydrocarbons.One of the most typical polycyclic aromatic hydrocarbons is benzo[a]pyrene,which has strong carcinogenic activity.Moreover,it has been proved by practice that they still have defects in terms of technology and use.This experiment uses liquid environmental-friendly binders,resin power and boron-containing additives to investigate its effects on the structure and properties of tap-hole clay.The shear test is introduced to evaluate the plasticity of tap-hole clay,and the influence of experimental materials and temperature on the plasticity of tap-hole clay is studied.The main results are as follows:(1)As the amount of liquid environmental-friendly resin added increases when it is added at 9-12%,the amount of volatile and decomposition of binder and the apparent porosity gradually increases,while the bulk density,the cold crushing strength,the hot modulus of rupture and the oxidation resistance decrease.Meanwhile,this also causes the significant linear change of tap-hole clay.The liquid environmental-friendly resin can significantly improve the plasticity of the waterless tap-hole clay,and tap-hole clay has good plasticity when added at 11%.The addition of liquid environmental-friendly binders has no obvious improvement on the slag resistance of waterless tap-hole clay,and tap-hole clay has excellent slag resistance.(2)As the amount of resin power added increases when it is added at 0-4%,the bulk density and oxidation resistance of two kinds of tap-hole clay decrease while the apparent porosity and linear change rate increase.Resin power leads to the tap-hole clay forming more loose structure,and the cold crushing strength of the sample after heat treatment at 1000 ?and 1450 ?and the hot modulus of rupture of the sample after heat treatment at 1000 ? gradually decrease.Resin powder and liquid environmental-friendly resin have different effects on the slag resistance of the tap-hole clay,but the difference in performance is small,which has little effect on the slag resistance of the waterless tap-hole clay,but significantly promotes the slag resistance of the water tap-hole clay.(3)Boron-containing additives improve the sintering properties of the tap-hole clay.Boron-containing additives promotes the formation of in-situ mullite which forms interlaced network structures.It compensates for the volume shrinkage of the binder after carbonization,which increases the bulk density of the two types of tap-hole clay and reduces the apparent porosity.Adding 6% boron-containing additives of the two kinds of tap-hole clay,the cold crushing strength increases by about 50%,and the hot modulus of rupture increases by about 100%.(4)The plasticity of the tap-hole clay varies regularly with temperature.When the shear test and the Marshall value method are jointly used to evaluate the plasticity of the tap-hole clay,the curves show almost the same change.By fitting the curve of shear stress as a function of temperature,the temperature range of the main flow position of the tap-hole clay and its value of the shear stress can be obtained.(5)Compared with the commercial tap-hole clay,the tap-hole clay studied in this subject has the characteristics of green environmental protection,suitable Marshall value,line change rate,the bulk density,apparent porosity,the cold crushing strength,excellent slag resistance and oxidation resistance,and has broad market application prospects.