| 摘要 |
1,157,675. Boric oxide. UNITED STATES BORAX & CHEMICAL CORP. 12 Aug., 1966 [22 June, 1966], No. 36276/66. Addition to 1,133,434. Heading C1A. Vitreous boron oxide is produced when a feed mixture formed by mixing sulphuric acid of at least 78% by wt. H 2 50 4 concentration, and an alkali metal or alkaline earth metal borate or mixtures thereof is heated at a temperature in excess of 1090‹ C. to form a molten reaction having two layers which are separated from each other while molten, and that layer containing the boric oxide cooled to give the desired product. A preferred heating temperature is 1200‹ C., and preferred borates are any sodium borate, e.g. Na 2 B 4 O 7 SH 2 O. The process is convenient for use as a continuous process when the mixture is continuously fed to a heating zone and the two molten layers are continuously separated, the boron-oxide containing layer being the upper one, preferably by means of a weir or dam situate in the bottom of the furnace, the separated layers coded and the desired product and by-product obtained. The boron oxide layer may be subject to further heating to remove impurities prior to cooling and solidification. |
