Method of producing lightweight inorganic insulating material

Claim 1

PROCESS OF PRODUCING A HEAT-INSULATING MATERIAL HAVING A DENSITY OF FROM ABOUT 13 TO ABOUT 20 POUNDS PER CUBIC FOOT WHICH COMPRISES SUSPENDING A MIXTURE OF ASBESTOS FIBERS, A FINELYDIVIDED POZZOLANIC SUBSTANCE AND A MATERIAL CAPABLE OF YIELDING AN ALKALINE EARTH HYDROXIDE IN AT LEAST ABOUT FIVE TIMES ITS WEIGHT OF WATER AND SUBJECTING THE RESULTING SUSPENSION TO SUFFICIENTLY TURBULENT AND VIOLENT AGITATION TO PRODUCE A VERY SLOWLY SETTLING SLURRY, HEATING SAID SLURRY IN A QUIESCENT CONDITION TO A TEMPERATURE BETWEEN ABOUT 185* F. TO ABOUT 300* F. BUT WITHOUT VAPORIZATION OF ANY SUBSTANTIAL AMOUNT OF ITS CONSTITUENT WATER UNTIL, AS A RESULT OF THE REACTION BETWEEN THE COMPONENTS OF THE MIXTURE, THE SLURRY SETS UP INTO A SPONGY MASS; BREAKING UP SAIS SPONGY MEANS WITH A MINIMUM OF AGITATION TO PRODUCE PIECES SUITABLE FOR TRANSFER TO A MOLD, TRANSFERRING SAID PIECES INTO A FORAMINOUS MOLD AND RAPIDLY COMPRESSING THEM THEREIN INTO A COHERENT SHAPE WHILE EXPRESSING WATER THEREFROM, HARDENING THE THUS PRODUCED SHAPE BY HEATING IT UNDER SUPERATMOSPHERIC STEAM PRESSURE, AND FINALLY DRYING THE RESULTING ARTICLE.