Phosphate mines produce large quantities of waste rock. These waste rocks are mixed and managed on the surface as large unrestored piles, which makes them difficult to rehabilitate. They primarily comprise carbonates, clays, marls, and cherts (flints). In many cases, the unrestored mine sites, when exposed to normal climatic conditions, could frequently produce toxic environmental pollution, and significant ecological disruptions. This research aims to assess the phosphate waste rock's (PWR) geochemistry and environmental behavior upstream of the extraction process. For this purpose, different core drilling specimens and data were collected from different lithologies and depths in the interlayers of the Benguerir mine to forecast the environmental profile and determine the mobility of the analyzed chemical species. These samples were analyzed for their petrographical, chemical, and mineralogical compositions, static leaching tests, and semi-dynamic test. The mineralogy results showed that the PWR mainly consists of calcite, dolomite, apatite, and quartz, with minor phases such as clay minerals. Chemically, the PWRs are dominated by the following major oxides: CaO and MgO, followed by SiO2 and P2O5. Trace elements can be classified into three groups based on their concentrations: group of Sr, Zn and Cr (> 150ppm), group of Ba, V, Ni, Zr, Y, U, Cu, Cd, Co (10-150ppm), and group of trace elements with relatively low concentrations (< 10ppm): Rb, Pb, As, Mo, Se, Sc, Ga, Nb, Th, Hf, Sb and Cs. Environmentally, the pH of the leachates was neutral to alkaline (6 ± 0.6-9.3) for all the samples, which have a high neutralizing potential (38-991kg CaCO3/t). The release of major and trace elements in the leaching test remains below international standard limits. Consequently, the leaching test results confirm the non-hazardous nature of the PWR. Therefore, the studied PWR could be considered a natural raw material and can be used in various applications in different sectors, such as civil engineering, cement industry, phosphate recovery, and acid mine drainage treatment through neutralization.
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