Method for producing high purity silica from kaolin clay

Claim 1

A PROCESS FOR PRODUCING A HIGH PURITY SILICA IN HIGH YIELDS FROM KAOLIN CLAY COMPRISING FORMING A HOMOGENEOUS COMPACT MASS OF UNCALCINED KAOLIN CLAY AND A 150 PERCENT TO 275 PERCENT DOSAGE OF SULFURIC ACID IN THE FORM OF A CONCENTRATED AQUEOUS SOLUTION OF A LEAST ABOUT 62 PERCENT CONCENTRATION, AGING SAID MASS WHILE IN DIRECT CONTACT WITH AIR AT ATMOSPHERIC PRESSURE OF A TEMPERATURE OF FROM ABOUT 300*F. TO ABOUT 1400*F. AND FOR A TIME SUFFICIENT TO CONVERT SUBSTANTIALLY COMPLETELY THE ALUMINUM ORIGINALLY IN SAID CLAY INTO AN ALUMINUM SULFATE REACTION PRODUCT, WHILE MAINTAINING THE REACTANTS IN INTIMATE CONTACT WITH THE NONVOLATILE REACTION PRODUCTS UNTIL SUCH REACTION IS COMPLETE, AND LEACHING THE AGED MIXTURE WITH WATER TO DISSOLVE SUBSTANTIALLY ALL OF THE RESULTING SOLUBLE REACTION PRODUCTS THEREBY PROVIDING THE DESIRED HIGH PURITY SILICA AS A RESIDUE.