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In this work, the medium-low grade calcium-magnesium phosphate ore in Zhijin, China, was investigated through systematic mineral processing studies using a scanning electron microscope, x-ray fluorescence spectrometer, and BGRIMM process mineralogy analyzer in combination with the ImageJ software and flotation experiment. The aim of this study was to suggest a process flow to optimize the flotation index of Zhijin phosphate ore. The effect of the liberation properties of fluorapatite on flotation behavior were analyzed with various particle sizes under different grinding fineness. Based on the characteristics of fluorapatite, we propose a double reverse flotation process with two routes for coarse- and fine-grained ore, respectively. The results showed that the flotation process can effectively improve the grade of phosphate ore and reduce the MgO content. As the degree of liberation increases, the flotation index increases first, and when the liberation degree reaches a certain value, the flotation index decreases. The maximum grade of fluorapatite was obtained for a grinding fineness of 82.86%, while the maximum grade of P2O5 was obtained for the − 53 + 38-μm particle size for flotation concentrate at various particle sizes. [ABSTRACT FROM AUTHOR]

The Bipindi iron ore district is located in the central section of the Nyong Complex at the northwestern margin of the Congo Craton in Southwest Cameroon. This iron district contains numerous iron mineralization hosted by the Mewongo, Bibole, Kouambo, and Zambi banded iron formations (BIFs). These BIFs contain magnetite as the main iron ore mineral associated with pyrite, and gangue minerals are quartz with minor chlorite and amphibole. The origin of iron ore from these BIFs was investigated using a combination of in-situ magnetite and whole-rock chemistry. The studied BIF ore samples have a narrow range of TFe between 30.90 wt.% and 43.20 wt.%, indicating a low-grade ore. The geochemical signatures of magnetite such as low contents of base metals (e.g., Cu, Co, V, and Zn) and low Co/Zn ratios < 0.85 indicate a hydrothermal origin. Combined with the geochemical features of these BIFs, e. g., high Fe/Ti and Fe/Al ratios (mean > 600 and > 75, respectively), we suggest that magnetite was derived from a mixture of seawater and ∼0.1% low-temperature hydrothermal fluids in an oxidizing environment. Collectively, low-temperature hydrothermal and later metamorphic fluids were necessary for the transformation of the protolith Nyong Complex BIFs to iron ore. [ABSTRACT FROM AUTHOR]

Geothermal energy is one of the solutions for energy issues in sub-Saharan countries such as Cameroon, while addressing the environmental issues of the Paris Agreement. This study provides a new database on heat flow, radiogenic heat production, and geothermal gradient for the Adamawa region in Central Cameroon, which suffers from energy issues. This database serves as a framework for future research on geothermal energy for this region. Specifically, the study uses spectral analysis of Grid Earth Magnetic Anomaly (EMAG2) to present an overview of the thermal structure anomaly from surface events related to the volcanic activity of the Adamawa region. This spectral method has been applied to the magnetic data from the equator. The magnetic map was obtained from the correction of the reduction at the equator divided into 17 overlapping blocks of 100 × 100 km in order to estimate the Curie point depth (CPD), which allowed us to obtain the values for the heat flow, radiogenic estimate, and P-wave velocity (Vp). The depths vary from 16 and 41 km, while the heat flow varies from 91 to 98 mW m-2. The Adamawa region is characterized by low Curie point depth values due to the identified geothermal gradient regime that reveal the influence of near-surface mantle convection. In this region, the radiogenic heat production ranges from 0.024 to 0.303 μW m-3, with the low radiogenic heat values being related to heat flow. The seismo-tectonic activity in the region only involves high-intensity earthquakes produced along the Cameroon Volcanic Line as a subduction zone more precisely in the locality of Woulndé. The heat flow observed from the data may suggest the existence of an anomalous heat source in the crust due to radiogenic heat results. [ABSTRACT FROM AUTHOR]