| abstract |
This application discloses two novel binding compositions for making silicate bonded cores and molds. In one of the binding compositions disclosed ammonia or an amine such as an ethanol amine is added to a concentrated alkali metal silicate in the amount generally in excess of 1 or 2 percent, but not so much as to decrease the solids content of the sodium silicate to more than about 95% of its original concentration. The precipitation or gellation which normally occurs in such systems can be dispersed by intensive mixing. The second novel composition is an adjuvant suitable for use in silicate bonded sands, which adjuvant is obtained by reacting a reducing sugar, an optional dicarboxylic acid or acid anhydride and boric acid. The dicarboxylic acid or acid anhydride comprises from 0% to 12% by weight of mixture, the boric acid comprises from 1/2% to 2% of the mixture and the balance is the reducing sugar. |