Application of selective-flocculation flotation on a high clay, ultrafine stream

The application of insoluble mineral flocculation-flotation on an ultrafine, high insoluble mineral (insol) content stream utilizing flotation column technology was evaluated as an alternate method to dissolution in separating insoluble minerals from residual salts in fine potash tailings. This study was a novel application of insoluble flocculation-flotation due to the high insol composition, the ultrafine particle size distribution, and the use of column flotation technology, which has yet to be implemented in a slimes flotation duty on an industrial scale. The feed insol content was 5-25 times higher than typical slimes flotation applications with a P80 of 30 µm compared to 3350 µm. A twelve-inch diameter by five-meter-tall pilot column with an external cavitation sparging system was installed in the plant to trial slimes flotation of an ultrafine, high clay stream with an ethoxylated amine collector. The column operating parameters were optimized, and a statistical approach was taken to evaluate the flotation response and determine the flotation column sizing parameters. The results conclude that collector-less insol flotation utilizing column technology from a high clay, ultrafine stream was successful, with a modeled optimum of 88.2% insol rejection and 86.7% KCl recovery; however, the patented method of flocculation-flotation is invalid in this application, due to the observed destruction of flocs in the flotation pulp arising from the power intensity of the column external sparging system and the significant column residence time. Direct comparison of the pilot separation efficiencies with a more power-intensive flotation machine revealed that the selectivity performance of the column was equipment limited. Complete liberation of the insoluble minerals, a fundamental characteristic of the ultrafine stream, resulted in near-ideal separation efficiencies from sylvite at high insol rejection rates when sufficient power intensity was provided; however, individual insol mineral flotation was found to be unselective. Column flotation of the ultrafine high clay stream was characterized by a low carrying capacity of 0.9 t/h/m2 and a long residence time of 17 minutes. Sparger energy intensity, collector addition, pulp density, feed composition, and brine temperature were found to be statistically significant predictors of insol rejection (R2 = 80.47%).Applied Science, Faculty ofMining Engineering, Keevil Institute ofGraduat