Study On Preparation And Properties Of Internal Combustion Coal Gangue Sintered Square Brick

Based on coal gangue as the research object,and mixed with shale to improve its calorific value and the plastic index,make its can be used as the raw materials of sintered square brick,so as to achieve the purpose of the coal gangue utilization.The mixture ratio of raw materials,particle size grading of raw materials and sintering system were studied by calorimeter,liquid-plastic combine tester and comprehensive thermal analyzer,combined with single factor test,the effects of coal gangue content,forming pressure,sintering temperature and holding time on the properties of sintered coal gangue square bricks were studied with water absorption,compressive strength,linear shrinkage of drying and sintering,wear resistance and freeze-thaw resistance as indexes this article main research results are as follows:The plasticity index of raw materials can be increased by decreasing the particle size of coal gangue and shale.The plasticity index of sintering brick can be improved by adding shale to coal gangue.Increasing the content of fine particles in raw material grading can greatly improve the strength of sintering bricks,but also increase the shrinkage of dry and sintered products.Excessive content of fine particles will cause cracks in the dry bricks,and sintering will further increase the propagation of cracks.Based on the plasticity index,the linear shrinkage of drying and sintering,and the appearance of drying and sintering,the optimal particle size ratio A(35-100 mesh):B(>100 mesh)=1:2 was selected.With the increase of coal gangue content,the water absorption rate of sintered square brick gradually increases,and its compressive strength gradually decreases.Under the principle of maximizing the utilization of coal gangue and low technical cost,the strength requirement of MX type sintered brick can be reached when the content of coal gangue is 60%.The increase of the molding pressure can increase the compactness of the dry brick,reduce its drying shrinkage and reduce its linear sintering shrinkage.However,if the molding pressure is too large,it will affect the full sintering of the raw materials inside the green body and cause the green body to expand during the sintering process.The best forming pressure of sintered square brick is 10MPa.The increase of the sintering temperature can increase the strength of the sintered body in a short time,but with the extension of the holding time,too high sintering temperature will cause the liquid phase to appear on the outside of the body before the inside,which affects the internal sintering reaction.And too high temperature(temperature over 1100℃)and too long holding time(holding time over 4h)will dissolve more mineral phases and reduce the strength of the green body.Finally,the best firing temperature is 1000℃,and the best holding time is 3h.In the test,only the products with coal gangue content of 50%had slight frost flooding,and the occurrence of frost flooding could be reduced by increasing the content of fine particles in the raw material.Increasing the content of fine particles in raw materials,increasing the sintering temperature and decreasing the content of coal gangue can improve the wear resistance and frost resistance of sintered square brick.Finally,under the conditions of particle size grading of 1:2,coal gangue content of 60%,forming pressure of 10Pa,sintering temperature of 1000℃ and holding time of 3h,the final sintered product has a compressive strength of 38.5MPa,water absorption of 11.2%,no frost,mass loss of less than 0.5%and strength loss of less than 15%in 25 freeze-thaw cycles,and a pit length of 24mm.It is a class I wear-resistant product.In line with the standard specification GB/T 26001-2010"sintered pavement brick" MX type sintered pavement brick requirements.