The Bureau of Mines investigated a selective flocculation-flotation technique to remove insoluble slimes from low-grade potash ore in a continuous 45-kilogram-per-hour (100-pound-per-hour) process investigation unit (piu). This research is part of the Bureau's program to improve resource recovery from low-grade ores. Results showed that 84 percent of the insoluble slimes were removed from an ore containing 5.5 percent water-insolubles and 14 percent k2o using a Bureau-developed, cationic flocculant-glycol ester-diesel oil reagent. Subsequent potash flotation recovered 75 percent of the potash in a cleaner concentrate assaying 56 percent k2o. Concentrate leaching upgraded the product to market specifications of 60 percent k2o. An economic evaluation by the Bureau suggested that the rate of return on investment, after taxes, should be about 20 percent for such an enterprise.