| 摘要 |
1,209,537. Sodium carbonate. CHEMISCHE FABRIK KALK G.m.b.H. 19 July, 1968 [6 Sept., 1967], No. 34588/68. Heading C1A. Sodium carbonate is prepared by introducing a 20 to 60% by weight aqueous sodium hydroxide solution and a gas containing CO 2 into a saturated sodium carbonate solution in a proportion such that the reaction mixture contains an excess of up to 10% by weight of free sodium hydroxide, the temperature of the reaction mixture being adjusted by controlling the temperature of the gaseous or aqueous reactant or by indirect heating so that the difference in partial pressure of the water vapour contained in the gas and reaction mixture is sufficient to remove, with the waste gases, all the water in the aqueous reactant, continuously removing the resulting crystal sludge from the reaction mixture, separating the sodium carbonate crystals therefrom and recycling the mother liquor to the reaction mixture. |
