caractérisation physico-chimique et minéralogique de matériaux calcaro-dolomitiques en vue de la production de liants et produits dérivés

Due to their abundance and availability, limestone and dolomitic rocks are among the most valued resources in the world. As natural stones, they have many applications, both in trade and industrial sectors. Moreover, regardless of the scope of these materials, they must meet specific mineralogical and mechanical or physico-chemical properties, depending on the sector. Environmental requirements and sustainable management of mineral resources, have forced companies to reduce the value of naturally occurring materials, focusing oriented processing of waste materials or alternative approach. Moreover, technological developments have led to new applications requiring maximum purity of the material also led farmers to manage natural resources in a more rational manner.
Mbuji-Mayi Region in the Democratic Republic of Congo, has huge limestone and dolomitic deposit; located in the " Mbuji-Mayi Supergroup". Nevertheless, the city suffers from a serious lack of sustainable infrastructure to consolidate its development and remains dependent on the supply of construction and building materials from other regions, located sometimes more than 1000 km from the Mbuji-Mayi site. The aim of this thesis is to investigate the potential use of Mbuji-Mayi supergroup materials to produce binder or derivated products in a sustainable management of mineral resources way. Thus, dolomitic samples were taken from Kanshi S13B and S70 Lubi drill cores, while limestone facies are from artisanal quarries in the region. They were then prepared and characterized. Techniques used are: X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), thermogravimetric analysis and the differential scanning calorimetry (TG-DSC), optical microscopy (OM) and scanning electron microscopy combined with chemical microanalysis (SEM / EDX). The results obtained after raw materials characterization showed that the Mbuji-Mayi Supergroup contains pure dolomite (respective mean CaO and MgO contents of 20.5 and 30%), impure dolomites and impure limestones. uniaxial compressive strength test, water absorption coefficient, and porosity were measured. Results were satisfactory in terms of the use of materials such as rubbles or building stones. Thermal and microscopic analyzes of pure dolomite, showed that these materials have high added value in the areas of refractory, glass manufacture or dolomitic lime production. Finally, a binder (CS1c) prepared from impure limestone, posted quite sufficient characteristics for applications with low mechanical stress. Metakaolin prepared from local raw material, was used to improve the characteristics of the binder CS1c. The analysis of the properties of the mixture CS1c-metakaolin, helped us to understand the role of some mineral phases, in contributing to the development of mechanical strength of such binders.