The Use of Black Fly Ash at the Production of Ceramics Materials - Part II

Abstract

This contribution is a presentation or results aimed at verification of possible utilization methods of ashes – solid wastes from combustion of black coal in fusion boilers as one of the components in ceramics production. Firing process of ceramics depends on properties of used ash and desired properties of ceramic material. Firing process is positively affected by morphology of inorganic and organic matter: surface areas a pore volume, equal settling vellocity of individual components. Dried bricks with constant addition of ash 25% wt. And 75% wt. of ceramic raw material were placed in laboratory owen. Properties of ceramic bricks were tested at thermal holdups for 15, 60 and 90 minutes during firing in laboratory owen at 650 to 950 ° C. Burnout of unburned coal residuals (UCR) starts in the ash at 650 ° C, which was completed using lower temperature gradient of 10 K.min -1 at 950 ° C and using 25 K.min -1 temperature gradient the burnout was not complete even at 1000 ° C, with only 20,7% of UCR from 25,5% LOI burned out. Limiting condition is heating capacity of ash and ceramic raw material, which does not exceed 840 KJ.kg -1 . Burnout of UCR in ash is during temperature changes affected by content of inorganic matter. Burnout of UCR in ash is slower as burnout of coal, because UCR particles does not contain volatile matter.