Separation strategies for Jordanian phosphate rock with siliceous and calcareous gangues

Separation strategies for Jordanian phosphate ore with siliceous and calcareous gangues were investigated by combined beneficiation and characterization techniques. To avoid ore resource waste and save the separation cost, it is noteworthy that different size fractions of Jordanian phosphate ore produced by sieving should be processed by different methods. The 74–300 μm size fraction which has fewer gangues than coarser and finer size fractions is treated by scrubbing to increase P2O5 grade up to 30%. The coarser size fraction (> 300 μm) requires secondary grinding. The finer size fraction (< 74 μm) with 23.85% P2O5 grade is processed by flotation to remove quartz gangue. The acid conditions can improve the flotation performance remarkably. The dissolution of carbonates at low pH value facilitates the quartz flotation. At pH 4.8, the P2O5 grade, P2O5 recovery and quartz removal ratio are 30.82%, 82.00% and 62.20%, respectively. Calcination can be employed to separate calcite gangue; however, it should be applied after quartz flotation to avoid the formation of CaSiO3 phase. To improve the flotation performance, the amount of < 45 μm particles should be reduced, and an alternative method is avoiding over-grinding.

Research Highlights
► Separation strategies for siliceous and calcareous phosphate ore are consisted of sieving, scrubbing and flotation.
► Sieving is the important first step. Different size fractions of Jordanian phosphate ore are produced.
► The > 74 μm size fraction is treated by scrubbing to increase P2O5 grade up to 30%, except > 300 μm size fraction which needs secondary grinding.
► The < 74 μm size fraction is processed by flotation to remove quartz gangue. At pH 4.8, the P2O5 grade is increased from 23.85% to 30.82%.
► Calcination is an alternative method to separate calcite gangue from < 74 μm size fraction, but it should be applied after quartz flotation.