An improved process for the dispersal of mineral raw materials by chemical action

摘要

Mineral raw materials, which contain at least 3 per cent of combined carbonic acid in addition to considerable proportions of other constituents, are disintegrated by treatment with a dilute solution of a mineral acid or acid salt in such proportion that the carbonates only are decomposed and are converted into bicarbonates. Specified raw materials are oxides and hydroxides, particularly of iron and aluminium, silicates and hydrosilicates, phosphates, fluorides and earth colours. In the treatment of minerals containing a higher percentage of calcium than of magnesium carbonate, it is preferred to employ sulphuric acid or acid sulphate, or a normal sulphate in conjunction with another acid or acid salt, so that the lime is converted into calcium sulphate, which absorbs the greater part of the water and yields a dry product or a paste, which may be employed as such. The process may be preceded by a grinding operation. In an example ochre, containing 3 per cent of carbonic acid in the form of calcium carbonate, is treated in a mixing apparatus with sulphuric acid. The powdered product may be graded by washing.