Processing of low-grade phosphate ores of Djebel Onk mine (Algeria) with electrostatic separation method

Phosphate ore is an important raw material for manufacturing phosphorous fertilizers and chemicals. Although most phosphate resources cannot be marketed directly as raw material, including that from the Djebel Onk mine, due to their low P2O5 content and high impurity content. To obtain a quality phosphate concentrate, the enrichment of low-grade phosphate ore is therefore of great necessity. The objective of this research was to explore the use of mixtures consisting of three beige phosphate sub-layers and two black phosphate sub-layers as feed material. The objective of this study was also to identify the chemical composition and mineral phases of the ore by various analysis techniques (X-ray diffraction, X-ray fluorescence, SEM / EDS scanning electron microscope, and optical microscope). Many beneficiation techniques can be used to improve the P2O5 content of phosphate ores depending on their characteristics. This technique of electrostatic separation gave excellent results in terms of content and recovery for both calcined and non-calcined beige and black phosphates. The removal of organic matter and calcite is crucial in the phosphate industry, wherefore high-quality phosphoric acid can be produced more economically, while reducing acid consumption. The best-obtained results from the calcination process followed by electrostatic separation from an initial ore with a content of 31.15 % of P2O5 were achieved for calcined beige phosphate (under conditions: rotation speed: 30 rpm, electrical voltage: 30 kV), with content of P2O5 in concentrate 36.89 % and recovery of 93.91 %. For calcined black phosphate the best results were achieved under conditions: rotation speed: 50 rpm, electrical voltage: 35 kV, with content of P2O5 in concentrate 36.65 % and recovery of 93.88 % from an initial ore (with a content of 30.85 % P2O5). This study highlights the importance of the calcination treatment before the electrostatic separation operation.