| 摘要 |
1,157,677. Boric oxide. UNITED STATES BORAX & CHEMICAL CORP. 15 Aug., 1966 [13 May, 1966], No. 36474/66. Heading C1A. In preparing a feed mixture for the production of boric oxide by mixing at least one borate selected from alkali metal and alkaline earth metal borates with sulphuric acid the major portion of the borate used has a particle size smaller than 100 mesh U.S.S. sieve. The sulphuric acid and borate are preferably mixed in equimolar amounts and the acid employed has a concentration of at least 90% by weight sulphuric acid. Up to 10% by weight excess of acid in respect of the equimolar quantities may be used in the mixture and preferably 80% by weight of said borate has a particle size smaller than 100 U.S.S. mesh e.g. a size in the range -1O0 +400 U.S.S. mesh. The acid may be sprayed on to the boratewhilst mixing is in progress, and the mixing is continued to give a free flowing granular feed mixture. Boric oxide is obtained from the mixture by heating it to a temperature of at least 750‹ C. to form a two layer molten product and separating the upper boric oxide layer. |
