GB748443A - Improvements in or relating to sodium carbonate monohydrate and anhydrous sodium carbonate - Google Patents

Abstract

Sodium carbonate monohydrate, having substantially all its crystals in the form of rectangular parallelopipeds, whose longest axis is not more than twice the next longest axis at right angles, preferably cubes, instead of the usual form of bipyramidal orthorhombs whose longest axis is usually 2 1/2 times the next longest at right angles, is produced by hydrating soda ash in the presence of an organic sulphate, or sulphonate, or a water-soluble salt thereof, as crystal modifying agent. Light ash at 160-200 DEG C. and excess, say 20-40 per cent of the ash, water at 50-90 DEG C. containing 0.05-0.3 per cent of the modifying agent may be fed to a cylindical, rotary mixer and maintained at 90-107 DEG C. until crystallization occurs. The resulting crystals may be passed to a rotary drier from which dense anhydrous sodium carbonate is obtained. Suitable organic sulphates and sulphonates include RO-SO2-OH or R-SO2-OH where R is a hydrocarbon radical of at least 6 carbon atoms, and salts may be those of alkali metals and ammonium. Specified modifying agents are:-benzene and naphthalene sulphonic acids, p-sodium sulphonates of toluene and xylene, isopropyl naphthalene sodium sulphonate, 2, 3-diisopropyl benzene sodium sulphonate and the corresponding diethyl, dimethyl, and dipropyl compounds, kerosene sulphonic acids and their salts, sodium octyl sulphate, sodium lauryl sulphate, and sodium cetyl sulphate, and the corresponding ammonium and alkylol-amine salts, sodium benzyl sulphonate, sodium salt of phenyl propyl sulphuric acid, dioctyl sodium sulphosuccinate, and the corresponding diisobutyl, diamyl, and dihexyl esters, naphthol sulphonic acids, naphthylamine sulphonic acids, and Turkey-red oil.