SOURCE COMPOSITION FOR ALKALI METAL OXIDES AND ALKALINE EARTH METAL OXIDES

1,260,198. Alkaline compositions; glass batch materials. DOW CHEMICAL CO. 23 April, 1969 [26 April, 1968 (2)], No. 20828/69. Headings C1A and C1M. A compound of the formula Na 2 Ca(OH) 4 , for use as an additive in glass making processes, is produced by reacting an inorganic calciumcontaining material which consists of or includes CaCO 3 with an aqueous solution of an alkali metal hydroxide at a temperature sufficient to form the adduct of calcium hydroxide and the alkali metal hydroxide and to evaporate a major proportion of the water. The inorganic calciumcontaining material is preferably a mixture of calcium carbonate and an oxide and/or hydroxide of calcium and/or magnesium e.g. pulverized limestone or dolomite. The resulting adduct may also contain minor proportions of Na 2 CO 3 , Ca(OH) 2 and CaCO 3 . The adduct may subsequently be pelletized and dried or dried and then reduced to particulate form. The adduct or an alkaline composition also comprising the compounds indicated above are used as a source of alkali metal and alkaline earth metal flux oxides in glass-making processes.