Preparation And Study On Characteristics Of Fly Ash Porous Ceramics

Over the past 8 years, fly ash emissions in China had increased 2.5 times, so it has become the single largest source of industrial solid waste. With the development of industry, fly ash emissions will continue to increases, meanwhile, this will bring serious hazards to environment and human health. How to substantial and high value-added utilize fly ash is a big problem which is placed in front of us. In this paper, I researched using fly ash as main raw material to prepare green materials porous ceramic the fly ash as main raw material preparation of porous ceramic green materials, achieve the purpose of utilization and exploitation of fly ash.This paper used particle packing method and adding pore-making agent method, selected the coal, starch, calcium carbonate as three kinds of pore-making agent, studied the effect of framework material size, pore-making agent type and dosage, sintering temperature, holding time, forming pressure on the apparent porosity, bending strength, water absorption, bulk density of porous ceramic, analyzed the crystalline phase composition, microstructure and other properties of sample by XRD and SEM.The results show that the most suitable pore-making agent is coal. As for the prepared porous ceramic of using coal, with increasing dosage of pore-making agent, the porosity and water absorption increased while the bending strength and bulk density decreased and they form linear relationship. With increasing sintering temperature, holding time, shaping pressure, the porosity and water absorption decreased while the bending strength and bulk density increased.Using XRD analyze fly ash porous ceramic which was prepared by different dosage pore-making agent, the results showed that its main phase are mullite and anorthite, in addition to small amounts of quartz and Fe2O3,which show that the dosage of pore-making agent has no significant effect on the formation of crystal phase of porous ceramic. Using SEM analyze topography feature of fracture surface of porous ceramic, the results show that the connectivity between pores are relatively strong while the shape and distribution of pore is irregular, the pore size from several micrometers to tens of microns forms gradient distribution.Use orthogonal experiment analyze pore-making agent dosage, sintering temperature, holding time, framework material size, shaping pressure on the effects of the apparent porosity, bending strength, water absorption, bulk density of fly ash porous ceramic. The greatest effect factor on the performance of porous ceramics is pore-making agent dosage and sintering temperature, holding time followed, forming pressure, aggregate size of the smallest. After the analysis of the experimental results to determine the optimal preparation program of fly ash porous ceramics about the additive 30%of pore-making agent, sintering temperature 1050℃, holding time 60min, forming pressure and framework material size of 160-180μm, the performance index of porous ceramic is porosity of 54.36%, bending strength of 6.63Mpa, water absorption of 45.21%, bulk density of 0.938g/cm3.