Beneficiation of Phosphate Solid Coarse Waste from Redayef (Gafsa Mining Basin) by Grinding and Flotation Techniques.

Sedimentary phosphate occurs largely at Gafsa mining basin. Among these occurrences Jebel Alima (Redeyf region) is an open pit quarry. After extraction, raw phosphate requires several stages of treatments to become concentrated: crushing, grinding, scrubbing, sizing, attrition, de-sliming and flotation. The coarse reject, generated from the first step of ore processing, constitutes the main pollution source in the mining area around the washing plant. Since composition contains a host of environmentally hazardous chemical elements such as Cd, U, Pb…. The results of the chemical characterization also show that the raw sample can achieve P 2 O 5 grade of 13.52%. After 170 scrubbing tests, with 4 kg of solid waste for each test, the liberated fraction showed a content of 24.33% P 2 O 5 . After sieving, the fraction under 315 microns was recovered for flotation, whereas the fraction greater than 315 microns goes through grinding. 11 grinding tests were carried out taking into account the parameter variations (rotational speed, grinding time, solid concentration and load). The result of the optimum grinding is: Load: 7/1; speed: 60 tr / min; time: 5,5 min; Cs: 45%. The liberated fraction content is 20.24%. Before the reverse flotation, the product from scrubber outlet (fraction <315 microns) and the ground fraction (> 315 microns) were mixed. The feed material has a content of 22.44% P 2 O 5 . The beneficiation of waste reject was carried out by reverse flotation in acid medium with amines and esters. The content reached 28.16% P 2 O 5 with carbonation rate of 1.6. This content is very close to 29% (content of commercial phosphates). Therefore the coarse waste reject could be considered as potential reserves for the future. [ABSTRACT FROM AUTHOR]