Impact of washing followed by calcination on the quality of bouchane phosphate of Morocco

Abstract

The aim of the present work is to compare two enrichment processes of the Bouchane phosphate. The first one is the usual calcination of the raw phosphate and the second is the calcination of the washed raw phosphate. We investigated the variation of some physicochemical properties, namely the specific surface, the volume mass and the mass percentage of the main constituents of the calcination of phosphates such as Organic carbon (Corg), Carbon dioxide (CO2), Phosphorus pentoxide (P2O5), and Lime (CaO), during these processes as a function of time and temperature. For this purpose, different analysis techniques were used such as the granulometric analysis, the quantitative analysis by volumetric method and by inductively coupled plasma atomic emission spectroscopy (ICP-AES), the mineralogical characterization by X-ray diffraction and differential thermic analysis coupled with thermogravimetric analysis. We concluded that a pre-washing a raw phosphate is critical to improving the quality of phosphates. A calcination at 800°C for 30 minutes reduces mass percentages of organic carbon by 88.60% and 91.43%, carbon dioxide by 53.00% and 54.54%, while the masses of P2O5 is increased by 9.15% and 10.46%, for the calcined raw phosphate and the raw phosphate washed and then calcined, respectively. It follows that the second procedure favors the reduction of energy consumption, which, in turns, is subsequently beneficial to the environment since it decreases the emission of CO2 by improving the quality through increasing the chemical reactivity and solubility.