Upgrading of Phosphate Fines by Fatty Acid Flotation Using Amylase Enzyme as a Surface Modifier

Phosphate fines (size ≤ 45 μm), from the Red Sea Region, Egypt, were subjected to beneficiation process to recover the phosphorite grains from such fines. The sample is characterized by low P 2 O 5 content (18.78%) associated with gangue minerals such as silica (22.77% SiO 2 ) and carbonate (2.01% MgO) indicating its low grade. Phosphate pre-concentrate was prepared by gravity separation, using Falcon, where 63.37% of the phosphate, with 24.94% P 2 O 5 , 1.46% MgO, and 10.54% SiO 2 , was firstly recovered reducing the mass flow to the subsequent beneficiation process. However, the gravity tailing was the feed for the reverse phosphate flotation using bench scale column flotation where oleic acid was used as a carbonate gangue collector and amylase enzyme as a phosphate depressant. Under the appropriate flotation conditions (0.1% amylase, 5·10 −4 mol/dm 3 oleic acid, and temp. 30 °C), phospho-concentrate assaying 0.61% MgO, 13.14% SiO 2 , and 27.85% P 2 O 5 with a P 2 O 5 recovery of 55.45%, was finally obtained without the use of expensive depressants, e.g., phosphoric acid or sodium silicate. A tentative flow sheet for the whole process was postulated.