Research On Preparation Of Hollow Ceramsite From Coal Gasification Slag

Coal gasification slag,a by-product of coal gasification,is one of the most discharged solid wastes in China.With the rapid development of coal chemical industry,the emission of coal gasification slag is increasing year by year.The massive accumulation of coal gasification slag not only occupies valuable land resources,resulting in the continuous deterioration of the ecological environment;but also the gasification slag itself contains high SiO₂,CaO,Al₂O₃,Fe₂O₃ and amorphous carbon and other resources that can be utilized as resources.However,the comprehensive utilization rate of gasification furnace slag is extremely low.Currently,gasification furnace slag is generally used to make clay bricks,substitute silica materials for cement clinker,and prepare porous adsorption materials or composite ceramic materials.Therefore,how to effectively utilize a large amount of coal gasification slag is of great significance to promote the sustainable development of China's coal chemical industry.Ceramsites are widely used in building materials industry because of its advantages such as small density,large specific surface area,high porosity,good chemical and thermal stability,thermal insulation and so on.Traditional ceramsite uses shale and clay which are non-renewable resources as the main raw materials,so it is not in line with Chinese national conditions to produce ceramsite by mining large quantities of non-renewable resources such as clay or shale.The main components of ceramsite materials are SiO₂ and Al₂O₃.The main components of coal gasification slag raw materials are SiO₂ and Al₂O₃,which have a very high compatibility with the components required for preparing ceramsite raw materials.In this study,hollow ceramsites were prepared from coal gasification furnace slag,and an innovative and feasible resource utilization way was found for the difficult utilization of coal gasification furnace slag.In this paper,coal gasification furnace slag from Xinjiang,Baoji and Weinan regions is selected as the main research object.Firstly,chemical wet analysis,X-ray diffraction?XRD?,scanning electron microscope?SEM?and other means are used to study the chemical composition,phase composition and microstructure of coal gasification furnace slag in Xinjiang,Baoji and Weinan regions.Then,hollow ceramsite was sintered at 750?,800?,850?and900?using coal gasification furnace slag from Xinjiang,Baoji and Beinan as main raw materials.The effects of temperature and viscosity on the foaming mechanism of hollow ceramsite were characterized by means of XRD,Factsage7.0 software simulation,SEM and thermal analysis and infrared.The research results are as follows:?1?There are differences in phase composition and microstructure of hollow ceramsite prepared from coal gasification furnace slag in Xinjiang,Baoji and Weinan with the increase of temperature;Hollow ceramsite with a density of 0.34?0.64g·mL^-1 can be prepared by sintering coal gasification furnace slag with medium temperature test furnace.?2?Through Factage7.0 software simulation,the viscosity of gasification furnace slag in Xinjiang,Baoji and Weinan gradually decreases with the increase of temperature,and the viscosity range of hollow ceramsite formed by blowing gasification furnace slag is consistent with the viscosity range of10²-10^6.6 Pa·s during glass forming.?3?The foaming mechanism of hollow ceramsites are investigated by means of thermal analysis and infrared with the coarse slag of gasification furnace from Xinjiang,Baoji and Weinan regions as raw materials.It is preliminarily indicated that the foaming mechanism of hollow ceramsites are caused by CO₂ and CO produced in a specific temperature range along with the rise of temperature during thermal analysis.