Enhanced Recovery of Coarse Particles During Phosphate Flotation
Lower recoveries of the coarse phosphate particles (-16, +35 mesh) are obtained in the industrial flotation operation. The aim of this study was to enhance the recovery of the coarse particles by collector (fatty acid and fuel oil) emulsification and froth modification achieved by frothers and fines addition.
An increase in flotation recovery with fines addition was observed. It was found that an optimum amount, size and collector coating on the fines is required. The increase in the flotation recovery under these optimum conditions was attributed to stabilization of froth by fine particles.
The increase in the flotation recovery of the coarse as well as fine particles was obtained with the emulsified collector. A correlation between flotation recovery, collector adsorption and froth stability was established. The increase in collector adsorption was attributed to the smaller droplet size obtained upon emulsification, which in turn was explained on the basis of increased hydrolysis of fatty acid.
Among the frothers examined, addition of two frothers–CP100 (a Westvaco Inc., product) and Dow XUS (a Dow Chemical Co. product) both at bench scale and in plant tests, yielded higher flotation recovery.
In plant tests, addition of CP 100 increased the coarse phosphate (-16, + 35 mesh) recovery by 6% while the fines (-35, + 150 mesh) recovery remained unchanged. Dow XUS addition, on the other hand, increased the finer fraction recovery by 6% and reduced the coarse flotation by 13%. The overall recovery, however, increased because the finer fraction constituted about 90% of the feed. The concentrate grade in all the cases remained unchanged.
Plant test with the emulsified collector resulted in more than 10% improvement in coarse phosphate as well as overall P2O5 recovery. The P2O5 content of tailings was also reduced by more than 10% as compared to when the non-emulsified collector was employed.