GB481100A - Process for separating soluble and valuable constituents from sylvinite ores and product or products obtained thereby - Google Patents

Abstract

To obtain potassium chloride from sylvinite ores, which consist mainly of sodium chloride and potassium chloride crystals together with small amounts of other mineral matter such as iron and manganese oxides, calcium and magnesium minerals, clays, &c., the sodium chloride and most of the other minerals are removed as a froth in a flotation process, the pulp being formed with a saturated solution of the ore, to which is added lead, bismuth, or both lead and bismuth. Any potassium chloride carried over in the froth is dissolved by heating and agitating the froth, the sodium chloride is then separated, and the liquid is mixed with the pulp from the flotation cells which contains solid potassium chloride. The mixture is cooled to crystallize the potassium chloride dissolved from the froth and sent to a dewaterer, the solid passing to a centrifuge where it may be washed with water or with saturated potassium chloride solution, and the liquid to a thickener which delivers the thickened product to the centrifuge. The potassium chloride obtained contains small amounts of oxides of iron and manganese and is of a pinkish colour. The granules are also coated with a water-repelling coating comprising lime and magnesium soaps formed by the combination of the fatty acid or soap used in the flotation with lime and magnesium salts in the ore. The water-repellent properties, which prevent caking &c. of the chloride during transit, may be increased by adding oils, e.g. mineral oils, animal oils such as red oil or oleic acid, or vegetable oils such as cottonseed or coconut oils, before, during, or after drying the separated product. The presence of lead and/or bismuth in the pulp is stated to prevent crystallization of potassium chloride, even if the pulp is slightly cooled, unless solid chloride is present as "seed."