The Bureau of Mines devised a direct flotation method for treating low-grade carnallite (kcl.Mgcl2.6H2o) and sylvinite (a mixture of kcl and nacl) ores characterized by a high content of water- insoluble impurities. The procedure consists of (1) flocculation- depression of the insoluble slimes, (2) decomposition leach (carnallite only), (3) potash rougher, cleaner, and recleaner flotation, and (4) final product leaching. The technique eliminates the necessity of removing the water-insoluble slimes by mechanical or flotation desliming. Laboratory results demonstrated that the direct flotation procedure, when compared with conventional techniques, yielded equivalent or improved flotation results with equal or less reagent consumptions. The direct flotation method recovered 81.6% Of the solid phase kcl from carnallite ore and 79.7% Of the kcl from sylvinite ore in final products containing 60.5% And 60.9% K2o. A flowsheet incorporating the described flotation procedure is presented.
Trans. Soc. Min. Eng. AIME, V. 272, May 1983, PP. 1974-1978