Beneficiation of low-grade carbonated phosphate ore by reverse flotation technics using anionic and cationic collectors, Sra Ouertane region, Northwest Tunisia

The aim of this work is to develop low-concentration carbonate phosphate from the Sra Ouertane region. Indeed, the Sra Ouertane low-grade phosphate ore needs an efficient process to remove the impurities, such as carbonates, silicates as well as clay minerals, to meet the requirements of the phosphate industries. Froth flotation is considered as the prevalent technology. In the present work, two stages of reverse flotation were applied on the raw rock undertaken from the A1 unit, Sra Ouertane region (Northwest Tunisia) after crushing and granulometric analysis. Ball crushing is a significant stage which allows a maximum release of the associated gangue. A stage of attrition and decantation was applied to eliminate the fine fraction (> 32 µm). The phosphoric acid (H3PO4) was used as phosphate-depressant and pH regulator, and PX6003 phosphoric ester and Noramac C26 amine were used as anionic and cationic collectors to float carbonates and silicates, respectively. After attrition and decantation, the P₂O₅ content increases from 18.39 to 22% and reached 31.57% after flotation with a recovery of 80.93% and (CaO/P₂O₅) ratio of 1.50.