Separation of valuable fine phosphate particles from their slimes by column flotation

Large quantities of fines are generated as slimes during beneficiation of p hosphate ores. These slimes are discarded due to the lack of a suitable met hod for their treatment. This decreases the total recovery of phosphate. Mo reover, the presence of these slimes causes an environmental problem in som e localities. This paper studies the possibility of recovering the valuable fine phosphate particles (<45 mu m) from their slimes through the applicat ion of the column flotation technique. Tests were performed using oleic aci d as a collector for the phosphate minerals, and sodium silicate as a depre ssant for their associated gangues. The: main operating parameters affectin g the performance of column flotation were investigated. The results indica te that the. best operating conditions for column flotation of phosphate sl imes are: superficial gas velocity 0.84 cm/s, frother concentration 0.1 kg/ ton, column height 230.5 cm, and superficial water velocity 2.2 cm/s. At th ese conditions a product assaying 25.3% P2O5 (similar to 55.24% BPL, bone p hosphate of lime) and 14.64% I.R. (insoluble residue) with a P2O5 recovery of about 51.52% was obtained from a feed containing 18.26% P2O5 (similar to 39.87% BPL) and 24.03% I.R. Such a grade and recovery were not obtained by applying the conventional froth flotation technique, even after cleaning t he rougher concentrate. Recovery of more than 50% of phosphate from dispose d slimes will improve the economic viability of the beneficiation process f or phosphate ores. It will also help in solving the environmental problems associated with the disposal of these slimes.