GB536409A - Process of purifying soluble substances containing insoluble earthy impurities - Google Patents

Abstract

536,409. Flotation processes. CAMPBELL, T. P., and JACOBSEN, W. B. Aug. 31, 1939, No. 25014. [Class 82 (ii)] In the purification of substances of natural and artificial origin consisting basically of one .or more readily soluble substances and insoluble earthy constituents as impurities, a pulp is formed by introducing the substances in finely divided condition into a saturated solution of the soluble constituent or one of such constituents and 'is then subjected to froth flotation in the presence of a re-agent having a selective affinity for the insoluble impurities such as a soap formed of a fatty acid such as oleic, lauric or palmitic acids or sodium salts of such acids in amounts up to 0.5 lb. per ton of material treated. An inhibiting or depressing agent such as sodium silicate may also be added especially when the substance to be treated is native rock salt. The froth characteristics of the re-agent may be sustained by introducing a polysaccharide into the solution. As applied to the purification of rock salt, the latter is mixed with saturated brine from the tank 2 and also sodium oleate and sodium silicate and fed to a grinding mill 1, such as a ball mill. The ground mixture is passed into a classifier 3 the overflow passing to a battery of flotation cells 4 in series, formed in two groups 4a, 4b additional re-agent being added only to the series 4c. The tailings from these cells is passed to a gravity separator 5 and the froth passes to a launder 4c and thence to an agitator 6 where it is bleached, the brine therefrom passing to a classifier 7 from which the overflow passes through a filter 8 to a pump 14 which returns the liquor to the tank 2. The liquid from the separator 5 is fed to a classifier 9, the oversize particles passing through a filter 10 to a drier 11, and through a screen 12 and is pulverized finally in a pulverizer 13.