Fabrication of low to high duty fireclay refractory bricks from lignite fly ash

The development of refractory bricks made of new materials has recently drawn a lot of interest to address sustainability issues. So, in this study, the recycling of lignite fly ash produced by coal-fired thermal power plants has been investigated to make fireclay refractory bricks. The lignite fly ash and ball clay are the primary raw materials characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray fluorescence (XRF), and differential thermal analysis (DTA). The samples were prepared using a uniaxial hydraulic press, and firing was done in the range of 1000–1200 °C for 2 h. The fired samples were characterized in terms of chemical composition, mineralogical phase, and microstructural using different characterization tools such as XRF, XRD, and SEM. The physical, mechanical, and thermal properties such as linear firing shrinkage, apparent porosity (AP), bulk density (BD), cold crushing strength (CCS), cold modulus of rupture (CMOR), and thermal conductivity of the fired sample were investigated. The linear firing shrinkage, AP, BD, and CCS values were achieved estimated to be 5.32%, 2.10 g m/cc, 15%, and 52 MPa, respectively. The SEM analysis shows dense, rod-like mullite structure and interlocking microstructure of the fired samples. The results were well matched with ASTM standards and commercially available products. So, this promising result indicates lignite fly ash can be used as a potential raw material to produce fireclay refractory bricks.