| 摘要 |
PCT No. PCT/AU81/00036 Sec. 371 Date Nov. 23, 1981 Sec. 102(e) Date Nov. 23, 1981 PCT Filed Mar. 26, 1981 PCT Pub. No. WO81/02728 PCT Pub. Date Oct. 1, 1981.Dihydroxyaluminium sodium carbonate is prepared by reaction between an ionic aluminium salt and a stoichiometric excess of sodium carbonate in aqueous medium in the presence of sodium hydroxide at a pH in the range 7.2 to 10.5. An amount of sodium carbonate at least ten times, and preferably fifteen times, by weight that of the aluminium salt is used and/or sodium salt by product, but not sodium carbonate, is precipitated from the aqueous medium. Preferably, the sodium salt is precipitated by saturation of the aqueous medium with sodium carbonate and sodium salt by-product at a sodium carbonate concentration less than the invarient concentration for sodium carbonate and consequently at a sodium salt by product concentration greater than the invarient concentration for sodium salt by product. The sodium carbonate-containing aqueous medium after separation of sodium salt by-product is reused as a source of sodium carbonate for subsequent reaction with additional aluminium salt. |
