GB482579A - Process for treating sylvinite ores and product or products obtained thereby - Google Patents

Abstract

Sylvinite ores, i.e. ores composed of naturally crystallized potassium chloride and sodium chloride together with clays and other gangue, are concentrated by forming a pulp by mixing the comminuted ore with a saturated solution of the ore, and subjecting the pulp to froth flotation to remove the potassium chloride as a froth concentrate. Any potassium chloride remaining in the pulp may be dissolved by heating the pulp, the solution being then separated from the solids. The solids are separated from the heated pulp by classification and thickening, a back-wash of sodium chloride solution being given to the solids in the classifier to produce a pure sodium chloride product. The sludge from the thickener is discharged to waste after washing and filtering. The excess potassium chloride is then removed from the thickener overflow by cooling in the presence of solid particles of potassium chloride, preferably those obtained in the froth concentrate; the chloride crystals are separated from the liquid by means of a classifier and a thickener, and the solids are washed with water or saturated potassium chloride solution. The solid potassium chloride obtained is of a pinkish colour owing to inclusions of iron and manganese oxides contained in the sylvinite ore, and it may also contain hydrous silicates of magnesium and aluminium. If desired, the potassium chloride may be dissolved to free the inclusions, which may be removed, e.g. by settling, and the chloride recrystallized on to other potassium chloride products.