Separation strategies for Jordanian phosphate rock with siliceous and calcareous gangues

摘要

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 P_2O_5 grade up to 30%. The coarser size fraction (>300 μm) requires secondary grinding. The finer size fraction (<74 μm) with 23.85% P_2O_5 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 P_2O_5 grade, P_2O_5 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 CaSiO_3 phase. To improve the flotation performance, the amount of <45 μm particles should be reduced, and an alternative method is avoiding over-grinding.