Study On Preparation And Properties Of Mixed Refractory For Coal Fly Ash And A Variety Of Industrial Solid Waste

Refractory materials and high temperature industry complement with each other.With the gradual upgrading and transformation of high temperature industry in recent years,refractory materials must keep pace with the national 13th Five-Year plan and adhere to the development and protection,resist the waste of natural resources.Advanced technology should be innovated in order to realize energy conservation and environment protection.Coal fly ash is the solid waste produced by thermal power plant.Excessive accumulation of coal fly ash as well as coal gangue,aluminum ash and tailings not only occupy the precious land resources,but also bring the soil environment,water environment and atmospheric environment to different levels of pollution.There are many valency compositions contained in coal fly ash,Al2O3 and SiO2 which are the main raw materials of mullite,account for more than 60%in coal fly ash.This research mainly focused on the recycle of coal fly ash and combined a variety of industrial solid wastes with the intention of preparing great performance and high value-added refractory materials.The study also analyzed the performance impacts of sintering temperature,proportion of raw material and molding pressure of refractory materials.Scanning electron microscopy(SEM)were used to analysis the microstructure characteristics of refractory materials.Composites of coal fly ash,aluminum ash and coal gangue were mixed to prepare clay refractory materials.The result showed a great physical properties and performance under a temperature of 1300℃ for 10 hours with the appending proportion of coal fly ash,aluminum ash and coal gangue of 50 wt.%,30 wt.%and 20 wt.%,respectively.The corresponding test results were as follows:apparent porosity of 26.43%,room temperature compressive strength of 46MPa,room temperature flexural strength of 15MPa,refractoriness of 1520 ℃ and permanent heating rate of+0.3%.The refractory materials performed a desirable physical properties and usability,which conformed to the national refractory material standard(YB/T5106-2009).XRD analysis was carried on different components and sintering temperature samples to illustrate that mullite and corundum phase were the main crystal phases.Therefore,the content of mullite increased with rise of sintering temperature.According to the results of uniform experiments,the refractory materials performed the best mechanical properties and physical properties under the sintering temperature and molding pressure of 1300℃ and 20MPa,respectively.The molding pressure put a great impact on apparent porosity,bulk density,compressive strength and flexural strength.While the sintering temperature showed a strong effect on both permanent change refractoriness and permanent heating rate.Based on the microstructure images and "eutectic" theory,which provided by the multivariate phase diagrams,it can be concluded that,the content of Al2O3 shows a directly impact on morphology and crystal form of the refractory materials.