METHOD OF SYNTHESIS OF ALUMINIUM SULFATE CRYSTAL HYDRATE Russian patent published in 2000 - IPC

FIELD: inorganic chemistry, chemical technology. SUBSTANCE: invention relates to methods of synthesis of aluminium sulfate crystal hydrate used mainly as coagulating agent for drinking water treatment. Method involves repulpation of aluminium hydroxide in water, pulp mixing with sulfuric acid to form melt, exposition of the latter up to complete decomposition of aluminium hydroxide at 100-120 C, addition of aluminium sulfate acid salt as finely divided seed containing 35-50% of water of crystallization at mole ratio Al₂O₃ : H₂SO₄ at the range (2:1)-(1:1) into melt followed by hardening melt cooled by air by its crystallization on moving surface cooled and wetted with water. Acid salt can be obtained by preliminary treatment of small-dispersed aluminium sulfate with sulfuric acid and in melt directly by means of sulfuric acid feeding to the latter after its exposition with sulfuric acid taken in the amount 0.08-0.25 part of H₂SO₄/100 parts of melt and small-dispersed aluminium sulfate taken in the amount 1-2 parts/100 parts of melt. Consumption of sulfuric acid used at mixing stage is corrected based on its consumption for acid salt formation. Method ensures to enhance the technological process by about 1.5-fold. EFFECT: improved method of synthesis, enhanced effectiveness of process. 4 cl, 1 tbl