Comparación entre radar del subsuelo de baja frecuencia y sísmica de reflexión de alta resolución para la detección de la seria fosfatada de la cuenca de Sidi Chennane (Marruecos)

Devido à importância dos depósitos fosfáticos de Sidi Chennane (Khouribga, Marrocos), a pessoa veio, enquanto explorando com sondagem eletromagnéticos no domínio do tempo (TDEM) e Sondagem Verticais Elétricas(SEV). Ambos tipos de investigação tiveram como objetivo a localização dos corpos estéreis que fican escondidos nas camadas de fosfato; e que são a causa principal de interrupção dos trabalhos de exploração mineira. E, embora para eles foram mostrados como métodos válidos para a localização destes corpos, apresentam a inconveniência que são métodos lentos na aquisição de dados de campo, si se faze conta das demandas de produção do jazigo. Durante dois anos, nosso grupo de investigação está avaliando a aplicação de rádar do subsolo (Ground Penetrating Radar method; GPR) como técnica mais rápida de aquisição de dados e obtendo de resultados. Para isto foi usado uma antena biestática de 40 MHz e o perfil ficava perto da frente de explotação para possuir um controle bom da geologia dos primeiros metros. Adicionalmente, na mesma linha de reconhecimento uma seção sísmica de reflexão de alta resolução (com geófonos de 40 Hz separado 5 m) foi obtida para ter outro método geofísico de contraste. Neste estudo nós apresentamos os resultados obtidos e a interpretação combinada deles.AECID, OCP, FEDER

Contribution of Gravity Data for Structural Characterization of the Ifni Inlier, Western Anti-Atlas, Morocco: Hydrogeological Implications

The Sidi Ifni region in southwest Morocco is mainly composed of crystalline rocks with limited groundwater storage capacity. These water resources drain in particular fault zones with high fracture permeability. The main objective of this study is to describe the geological structure of the region to optimize future drilling locations. The gravity data were processed using various techniques, such as total horizontal gradient, tilt derivative, and Euler deconvolution, in conjunction with the interpretation of the geological data, to create a new structural map. This map confirms the presence of many previously identified or inferred faults and identifies significant new faults with their respective trends and depths. Analysis of this map shows that major faults are oriented NNESSW and NE-SW, while minor faults are oriented E-W, NW-SE, and NNW-SSE. The superposition of the hydrogeological data and the structural map reveals that the high groundwater flow values in the boreholes are located in the vicinity of the major faults and talwegs. The structures deduced from the filtering and interpretation of the gravity data suggest that the hydrogeological system of the Ifni Inlier is controlled by its structures. To confirm this impact, a high-resolution electrical resistivity map (7200 Hz) was used, with penetration depths ranging from 84 to 187 m. Negative boreholes, located in high resistivity ranges corresponding to sound basement formations without fault crossings, showed high resistivity values. The positive holes, located in anomalies with low linear resistivity, revealed the impact of fault crossings, which drain water and tend to decrease the resistivity values of the formations. Therefore, these new structural maps will assist in planning future hydrogeological studies in this area

Field and Economic Studies on Mine Waste: Sustainable Reuse as Aggregates for Low Traffic Pavement Structure

The phosphate extraction and processing has followed a traditional linear consumption model, where wastes are continuously produced and surface land is filled in rock piles. Thus, to promote a circular economy in a mining context, more eco-friendly and sustainable solutions at the regional level are needed. This paper deals with the potential utilization of phosphate screening waste rock 0–100 mm (SWR) as alternative aggregates for pavement applications. Detailed in situ and laboratory tests have been made for SWR characterization, and the practical modalities of implementation have been defined. The findings proved that SWR (10–100 mm) materials can be successfully used without treatment in capping layer construction for low-volume traffic pavement projects. Due to its high apatite content, the remaining fraction (0–10 mm) can be exploited to recover the residual phosphate using the processing method that is currently followed by the mining company. Furthermore, the environmental investigations showed that SWR does not present any potential contamination risk to the surrounding environment. The economic feasibility analysis confirmed the workability of SWR reuse in a radius of 100 km around their dumps due to its lower cost compared to conventional aggregates. This simple amendment may ensure a smooth transition from a current linear extractive approach to a circular economy

Valorization of Phosphate Mine Waste Rocks as Materials for Road Construction

The road construction sector is a worldwide high consumer of natural aggregates. The use of unusual industrial by-products in road techniques can contribute to the conservation of non-renewable natural resources and the reduction of wastes produced by some industries. Phosphate waste rocks could be considered as potential alternative secondary raw materials in road construction. The use and valorization of these wastes is currently limited according to the Moroccan guide for road earthworks (GMTR). The guide has classified these materials as waste products, which consequently, cannot be used in road construction. However, phosphate waste rocks are sedimentary natural rocks which have not been subjected to any transformation other than mechanical fragmentation. The goal of this paper is to discuss key-properties of various phosphate mine waste rocks (PMWR) to be used as road materials. Samples were taken from different stockpiles in the phosphate mine site of Gantour in Morocco. The different waste rocks samples were characterized in terms of their physical, geotechnical, chemical, mineralogical and environmental properties using international testing norms. The obtained results showed that the studied PMWR presented satisfying characteristics; the specific (particle) density: ρs > 26 kN/m3, Los Angeles abrasion: 45% < LA < 58%), methylene blue value MBV < 1 g/100g, organic matter: OM < 1% and plasticity index: PI < 20%. All PMWR were confirmed as possessing the requested geotechnical properties to be used as materials for embankments. Moreover, leaching tests showed that none of them released any contaminants. In field application, these materials have been also successfully used in in situ experimental pilot testing. Therefore, the PMWR have to be classified in the category of natural aggregates that are similar to conventional materials