Evaluation of technological properties of fired clay bricks containing pyrrhotite ash

Abstract

This work investigates the recycling of pyrrhotite ash (PA) waste as a method to provide a secondary raw material for clay brick bodies. PA is an industrial waste mainly composed by iron oxide particles (64,9 wt%). It was produced during the production of sulfuric acid from the combustion of pyrrhotite ore. This waste was characterized by X-ray fluorescence, X-ray diffraction, Fourier transform infrared spectroscopy and differential thermal analysis. The morphology and distribution of particles size were also studied. Clay bricks containing yellow clay and different content of PA (10–50 wt%) were prepared, fired at 1000 °C and tested to evaluate their technological properties (e.g. linear shrinkage, water absorption, bulk density, apparent porosity and flexural strength). The microstructure of the sintered bricks was also evaluated by scanning electron microscopy (SEM). The test results indicate that the addition up to 30 wt% of PA waste to clay bricks could be used, which would enhance the possibility of its reuse in a safe and sustainable way.