Preparation Of Al₂O₃-SiC-C Composite Materials From Coal Gangue And Its Application In Taphole Clay Refractory Materials

Coal gangue is a kind of rock minerals with low carbon content,which is a large industrial solid waste in the process of coal mining because of its low added value and unsuitable for long distance transportation.The consumption of coal gangue is mainly in the paving,backfill coal and other building materials,but the coal gangue contains a large number of Al,Si and other useful elements,has been applied to industrial production of chemical raw materials such as the preparation of chemical fertilizers,4A molecular sieve,mullite clinker.However,due to the complexity of the preparation process,and the existence of a series of by-products,making coal gangue utilization and conversion rate is much lower.Based on this background,Al₂O₃-SiC composite powders with excellent properties were prepared by using carbon gangue as raw material and low cost carbonaceous material as reducing agent.The process parameters of Al₂O₃-SiC composite powders were optimized by adjusting the kind of reducing agent,calcination temperature,holding time and the mount of reducing agent.When the coke was used as the reducing agent,the calcination temperature was 1600 °C,the holding time was 5h,and the amount of reducing agent was over 50% compared with theoretical amount.The pure Al₂O₃-SiC composite powder was obtained in this condition,and the crystalline form of alumina is?-Al₂O₃,the crystalline form of silicon carbide is ?-SiC.In this thesis,the Al₂O₃-SiC-C-based taphole clay-refractory was successfully synthesized on the basis of the taphole clay-mortar formula of a steel plant,and the addition amount of Al₂O₃-SiC composite powder was also studied.The volumetric density,apparent porosity,line shrinkage,high temperature flexural strength and fracture morphology of the mortar samples at different temperatures were investigated.The results show that the addition amount of Al₂O₃-SiC composite powder has no negative effect on the conventional physical properties of the mortar sample.When the amount of Al₂O₃-SiC composite powder is 20%,the volumetric density of the taphole clay sample after treatment at 1600 °C is 2.48g/cm³,the apparent porosity is 20.62% and the flexural strength is 16.99 MPa.The results show that the addition amount of Al₂O₃-SiC composite powder increases the corrosion resistance to anti-slag of the taphole clay sample by using the static crucible method.The kinetics of corrosion resistance to anti-slag was studiedwhich the taphole clay samples with 20% addition of Al₂O₃-SiC composite powder were studied at different time.It was found that the erosion of blast furnace slag was pear-shaped,the erosion rate is 0.012 mm/min after the diffusion and equilibrium,and the erosion process is controlled by the chemical reaction and the diffusion process.