Phosphate waste rocks recycling in ceramic wall tiles: Technical performances

Abstract

The phosphate mining industry produces large amounts of waste rocks during the open-pit mining operation. In the present paper, phosphate waste rocks, abundant in different regions of Morocco, are investigated as a candidate material for partial/entire replacement of conventionally used industrial minerals. Several recipes for the production of tiles are tested, based on raw materials from five representative phosphate waste rocks mine sites and a raw clay from Safi's region in Morocco. The phosphate waste rocks are shown to be mainly composed of phyllosilicates (smectite, sepiolite, and palygorskite), carbonates (dolomite and calcite), and silica frameworks (quartz, tridymite, and cristobalite) as major phases. The raw samples and calcined mixtures were characterized by using X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), thermogravimetric analysis (TGA), and Fourier transformed infrared spectroscopy (FTIR). Properties analyses revealed that the produced ceramic tiles can be classified as porous bodies. The tiles based on 100% of phosphate waste rocks have shown excellent mechanical properties (∼55 MPa) in terms of compression and they can be used in the traditional wall tiles called “Zellige” in Morocco.