Industrial waste causes environmental, economic, and social problems. In Morocco, the Jorf Lasfar Thermal Power Station produces two types of coal ash with enormous quantities: fly ash (FA) and Bottom ash (BA). FA is recovered in cement while BA is stored in landfills. To reduce the effects of BA disposal in landfills, several experimental studies have tested the possibility of their recovery in the road construction, especially as a subbase. In the first phase of this study, the BA underwent a physicochemical and geotechnical characterization. The results obtained show that the BA should be treated to improve its mechanical properties. The most commonly used materials are lime and cement. In the selected low-cost treatment, which is the subject of the second phase of the study, lime is used to improve the low pozzolanicity of BA while calcarenite sand is used to increase the compactness. Several mixtures containing BA, lime, and calcarenite sand were prepared. Each of these mixtures was compacted in modified Proctor molds and then subjected to a series of tests to study the following characteristics: compressive strength, dry and wet California Bearing Ratio (CBR), dry density and swelling. The composition of each mixture was based on an experimental design approach. The results show that the values of the compressive strength, the dry density, and the CBR index have increased after treatment, potentially leading to a valorization of the treated BA for use in a subbase.

The Zellidja Lead Smelter Company (Eastern Morocco) was created by Jean Walter in 1939 for the purpose of transforming lead concentrates into pure metal. Its activity was always at the origin of the production of huge quantities of solid mining waste with granular aspect. Today, despite the definitive cessation of its production in 2012 due to the depletion of ore, millions of tons of slag are piled up between the back of the foundry and the watercourse of Oued El Heimer. This open-air storage site represents a significant environmental and economic risk resulting from the surface water and groundwater pollution. In addition, as part of the strengthening of the Moroccan construction sector and infrastructure (which requires enormous quantities of natural aggregates), studying the possibilities of using these by-products as building materials seems interesting. For these reasons, the objective of our research work is the characterization of Zellidja slag for their valorization in civil engineering. This valorization has three objectives: to solve the problem of the landfill of the mining waste, to search for an alternative material responding to the increased needs for granular materials and to protect the national patrimony in raw material. In order to ensure the feasibility of this valorization, these tailings were the subject of a complete characterization. The results of this characterization prove that these by-products with a granular aspect have interesting geometric, physical, chemical and mechanical characteristics favoring their valorization in concrete.

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The subsoil of Morocco is marked by a wealth of mineral resources (phosphate, lead, zinc, coal and others). For this reason, the mining sector is still considered one of the main pillars of the national economy. The Moroccan lead deposits are located mainly in the Atlas region and the Eastern region. The Zellidja lead smelter company has succeeded in distinguishing itself and being among the best lead smelters in Morocco. It is known nationally and internationally for its production of soft lead, antimonial lead oxide, fine silver, copper matte and triple alloy concentrate. The majority of its production is destined for international markets such as Europe, North Africa, Near East and Middle East. In addition, it is also recognized for its large capacity of processing lead concentrate from several mines. This capacity has obviously increased and decreased over time, depending on the number of mines exploited, the presence or absence of ore, the quality of the industrial equipment, the number of employees and other circumstances.