Chemical and Mineralogical Characterization of Chadian Diatomite for Industrial Valorization

Abstract

Diatomite, a microporous siliceous rock, is mainly used in northern Chad for housing construction due to its abundance and thermal insulation properties. However, the potential for industrial valorization of this noble material is underexploited due to a lack of complete physicochemical characterizations. The objective of this study is to determine the chemical and mineralogical properties of Chadian diatomite deposits to evaluate their potential for more diversified industrial applications. Six diatomite samples were collected around the city of Mao (Kanem region) and subjected to characterization by X-ray fluorescence (XRF) and X-ray diffraction (XRD). Chemical analyzes show that the samples are predominantly composed of silica (SiO2), with contents ranging from 49.94% to 88.97%, along with significant amounts of alumina (Al2O3, 3.48−5.62%) and iron oxide (Fe2O3, 1.32−3.37%). Two deposits (Koulola and Youlo) stand out due to high levels of calcium oxides (13.08% and 5.46%) and magnesium oxides (up to 4.38%), suggesting calcareous contamination. Mineralogical analyzes (Rietveld method) confirm the dominance of quartz (30.05−83.89%) in the majority of samples, as well as the presence of illite, plagioclase, and hematite. Notably, the Koulola deposit is dominated by plagioclase (41.93%) at the expense of quartz. The comparison with industrial specifications reveals that the Djoulou, Mobye, Motto, and Tchidi deposits, with silica contents exceeding 78%, are particularly well-suited for valorization in less demanding applications than filtration, such as mineral fillers, abrasives, and thermal insulation. This study provides the first database for promoting the exploitation of these resources in Chad.