Optimisation of the flotation parameters on the enrichment of phosphate ore (Algeria)

Abstract

Purpose. Treatment of the Algerian natural phosphate ore from the Jebel Onk deposit by flotation process with the use of flotation cell of the Motso Mineral Industries type (Inc. Darville, PA USA). This phosphate ore has a carbonate and silicate gangue, which negatively affects viscosity in the production of phosphoric acid. methodology. The experimental procedure used is based on two aspects: 1) a prior mechanical preparation of all the processes: crushing, homogenization, quartering, sieving, followed by attrition and desliming operations; 2) a preparation of reagents of different qualities followed by pulping, packaging and flotation. Findings. We can conclude that the reverse flotation is perfectly favorable and presents an excellent economic yield. The flotation process has shown its efficiency in depressed phosphatic elements in the phosphate concentrates (flowings) as well as in floated carbonates in the carbonated wastes (floatings). Indeed, it was possible to attain the phosphate concentrate contents of nearly 31 % in P2O5 with a satisfactory recovery (85‒95 %). Originality. Flotation tests are applied for both granulometric classes C1(40‒250 μm) and C2(250‒500 μm) treating a little more than 30 % of P2O5 with respect to raw sample (26 %), which allowed achieving satisfactory yields (85 to 95 %).The best yields were obtained under the following optimal conditions: the conditioning and flotation optimal time periods recorded for both classes are 10 and 8 min for class C1, whereas for class C2 they were found to be 7.5 min and 6 min, respectively. The best pH that corresponds to a higher flotation recovery for both classes is 9. The oleic acid adsorption optimal dosages on the gangue elements are 2500 and 2000 g/t for class C1 and C2, respectively. Practical value. Different analytical techniques (XRD, XRF, FTIR) were applied for the flotation products namely: the flowings (phosphate concentrate) and the floatings (carbonated waste), which allows a new approach in the optimization of exploitation and valorization of the phosphate ores, as well as the focus of organizational chart of the treatment, aiming to provide the best quality of the phosphate concentrate.