Study On The Preparation Of Lightweight Coal Gangue Porous Materials By Foam Gel Method

Coal gangue is one of the largest industrial solid wastes in China, and the negative impact on the environment caused by coal gangue is increasingly serious. Most of the utilization of coal gangue exhibited low value-added and inefficiency; preparation of inorganic functional materials in efficient and environment-friendly ways is the key technology to increase the value-added and the utilization of coal gangue. This paper employed coal gangue of Zixing Mining Bureau in Zhou yuanshan as raw material, using silica sol as gelling agent, the density of the coal gangue lightweight porous material is from 0.6 g/cm3 to 1.2 g/cm3 prepared by foam-gel method.The coal gangue of Zhou yuanshan is mainly contains Si O2 and Al2O3 with the chemical composition analysis, and the weight of sulfur only account for 0.11%, it contains mainly quartz and kaolinite with the mineral composition analysis for the coal gangue and belongs to the clay gangue; the sieving diameter of coal gangue decreased with the increasing of milling time gradually, The average particle size of coal gangue powder is 77.65 μm after milling 20 min and sieving with 28-mesh griddle, This coal gangue powder was used as raw material for the preparation of coal gangue porous material.Many Parameters such as the ratio of water to solid of the coal gangue slurry, the amount of gelling agent added, the amount of coagulant added, foaming agent types, drying systems and the sintering temperature were investigated in this paper, The results show that: the viscosity and foaming ratio of coal gangue slurry, and drying shrinkage of the green body were mainly influenced by the ratio of water to solid, mechanical strength of coal gangue porous body was mainly influenced by the gelling agent, coagulant mainly affects the gelation time, the types of foaming agent played important role on the foaming properties of the coal gangue slurry, the quality of dried green body was mainly influenced by the drying system, the linear shrinkage and compressive strength of the gangue porous material was determined by the sintering temperature. The main parameters of preparation are: the ratio of water to solid is 0.3, the gelling agent added is 30wt% of the weight of gangue powder, and coagulant added is 0.75 wt% of the weight of gelling agent, Coal gangue porous material with the density from 0.6 g/cm3 to 1.2 g/cm3 could be prepared with the sodium dodecyl sulfate as foaming agent, and coal gangue porous green body was dried by the first scheme, and finally sintered 3h at 1000 ℃, the pore structure of coal gangue porous materials are mostly closed, the distribution of its pore is uniform, and the average of its pore size is about 100 μm, the linear shrinkage is 6.89%, when the compressive strength is 3.85 MPa. The thermal conductivity coefficient of the coal gangue porous material is 0.144 W/(m·k)with the average temperature at 150 ℃, when the thermal conductivity coefficient is 0.240 W/(m·k)with the average temperature at 800 ℃.