New Integral Processes Enrichment of Moroccan Oil Shale using Mineral and Hydrometallurgical Methods

Abstract

In this work, we increase the calorific value of Moroccan oil shale, which is the main element in the combustion of fossil fuels. In particular, we consider the shale of Timahdit, enriching it by hydrometallurgical and mineral processing methods in order to use it to generate thermal and electrical energy. Although different studies have been conducted for the development of Moroccan oil shale, but they have not dealt with the axis as we have. Direct combustion of raw shale is difficult due to the presence of high carbonate content with 23.2% in the Timahdit oil shale and 40.2% in Tarfaya, and a total content of organic matter, respectively 17.7 and 16.25% [Bekri O. Possibilities for oil shale Development in Morocco. CAER-University of Kentucky, Center for Applied Energy Research 1992. 3(5) ]. During pyrolysis of raw shale, organic waste (residual carbon) obtained for both shales depends on the rate of heating (5 to 40°Cmin^-¹) [Barkia H., Belkir L. and Jayaweera S. A. A. Journal of Thermal Analysis and Calorimetry 2003. 71. 97p]. It turns out that there are three phases in the whole process: first, the concentration of carbon residue decreases with increasing heating rate. It stabilizes around 12°Cmin^-¹, then it continues to decrease at higher heating rates. The activation energies are determined using the Coats-Redfern. Our results in this paper show a change in the reaction mechanism at around 350°C. Below this temperature, the activation energy is 41.3 kJmol^–¹ for the decomposition of Timahtid oil shale, and 40.5 kJmol^-¹ for Tarfaya oil shale. Otherwise, the respective values are 64.3 and 61.3 kJmol^-¹. Using Timahdit oil shale of initial kerogen content of 17.7%, calorific value 1436 kcal/kg, and by performing a physicochemical treatment, we augment the organic matter to 60%. We get a calorific value ≥ 4500 kcal/kg and remnant products (sous- products), which depend on the nature of the used acid.