Abstract
The reverse flotation of calcareous phosphate ores, at acidic pH, usually uses anionic collectors such as oleic acid (Ol) and sodium dodecyl sulfate (SDS). However, using a mixture of two anionic collectors is very rare. In the present paper, a mixture of oleic acid and sodium dodecyl sulfate, with a ratio 1:1, was prepared. Different dosages of Ol-SDS mixture was studied in absence or presence of sodium sulfate as a phosphate depressant at different pH values. The results showed that sodium sulfate works better at highly acidic pH where 30.7 % P2O5 was achieved in presence of sodium sulfate in comparison to 29 % P2O5 at pH 4 and 0.5 kg/t collector dosage. However, by increasing the pH, the sodium sulfate negatively affects the concentrate grade. Moreover, the sodium sulfate maintains the grade and recovery almost unchanged within the studied pH range. Although a concentrate grade exceeds 30 % P2O5 could be achieved with or without addition of sodium sulfate, the highest concentrate grade of 33 % P2O5 was obtained with 85 % recovery at 3.5 kg/t collector dosage and pH 6 with no sodium sulfate additions.