Comparative evaluation of different collector–depressant systems application in the reverse flotation of apatite and collophane from a sedimentary phosphate ore sample

This study presents a comparative evaluation of various collector-depressant systems application in the reverse flotation of apatite and collophane from a low-grade sedimentary phosphate ore sourced from the Koh-e-Lar phosphate deposit. The ore, characterized by high carbonate (calcite) and silicate (quartz) impurities, underwent de-sliming via hydrocyclone to remove particles finer than 38 µm, reducing slime interference and resulting in approximately 12.2% P 2 O 5 loss in a single stage. Reverse flotation experiments were conducted to depress phosphate minerals while floating gangue, focusing on the effects of pH, collector types (oleic acid, Pamak 200, Armac T, OMC A 308, Pamak 4), depressant systems (aluminum sulfate-potassium sodium tartrate combinations), and collector mixtures. Optimal conditions were identified at natural pH (5–7), where oleic acid and Pamak 200 exhibited superior selectivity with enrichment ratios around 1.4. The 2:1 ratio of aluminum sulfate to potassium sodium tartrate provided the best depression, enhancing carbonate flotation. Collector mixtures of oleic acid: Pamak 200 at 30:70 and 50:50 ratios yielded the highest P 2 O 5 grades (up to 13%) and recoveries (rougher up to 90.1%, final up to 56.8% including slimes). These findings suggest potential complementary interactions between mixed reagents that improved selectivity and flotation efficiency, although further surface characterization would be required to confirm the underlying mechanisms.