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Abstract

An amorphous ceramic glass composition having a density greater than about 2.1 g/cm.sup.3 comprises: between about 35 and 55% by weight SiO.sub.2 ; between about 18 and 28% by weight Al.sub.2 O.sub.3 ; between about 1 and 5% by weight CaO; between about 7 and 14% by weight MgO; between about 0.5 and 5% by weight TiO.sub.2 ; between about 0.4 and 3% by weight B.sub.2 O.sub.3 ; and greater than 0 and up to about 1% by weight P.sub.2 O.sub.5. A convenient source of raw materials is a mixture of coal ash waste, borax (or boric acid) manufacturing plant waste, and titanium pigment waste. The ceramic glass is formed from an intermediate ceramic mixture which is subjected to a heat treatment. The intermediate ceramic mixture is formed by heating a mixture containing SiO.sub.2, Al.sub.2 O.sub.3, CaO, MgO, TiO.sub.2, B.sub.2 O.sub.3, and Na.sub.4 P.sub.2 O.sub.7 to a temperature between about 1400.degree. and 1600.degree. C.; cooling the mixture at a controlled rate between about 15.degree. C. and about 30.degree. C. to solidify it; annealing the mixture at a temperature between about 600.degree. and 670.degree. C. in an atmosphere containing oxygen; and cooling the mixture to a temperature less than about 400.degree. C. at a cooling rate between about 15.degree. and 30.degree. C. per hour. The intermediate ceramic mixture is first heated to a temperature of between about 850.degree. and 1000.degree. C. at a heating rate of between about 1.degree. and 2.degree. C. per minute, and then sintered at a temperature between 850.degree. to 1000.degree. C. for a time period sufficient to increase its density to at least about 2.1 g/cm.sup.3.

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