Process of producing high bulking finely divided silica

Claim 1

PROCESS OF TREATING A KAOLIN TYPE CLAY TO CONVERT THE SILICA CONTENT THEREOF TO A FINELY DIVIDED HIGH BULKING PRODUCT WITH SIMULTANEOUS PRODUCTION AND RECOVERY OF ALUMINUM SULFATE, WHICH COMPRISES DIGESTING AN UNCALCINED FRACTION OF A GEORGIA TYPE WATER-WASHED KAOLIN CLAY, SAID FRACTION BEING THE FINER CUT CONSTITUTING NOT MORE THAN 75% OF THE TOTAL, WITH AN EXCESS OF DILUTE SULFURIC ACID AND THEREBY CONVERTING AT LEAST THE GREATER PART OF THE ALUMINA CONTENT THEREOF TO ALUMINUM SULFATE, HEATING TO EVAPORATE THE WATER LIBERATED IN THE DIGESTING REACTIONS AND TO REMOVE AT LEAST A LARGE PART OF THE WATER OF HYDRATION OF THE REACTION PRODUCTS, THEREAFTER FILTERING AND WASHING TO REMOVE THE ALUMINUM SULFATE, THEN TREATING THE SILICA RESIDUE WITH CONCENTRATED SULFURIC ACID, EVAPORATING THE RESULTING MIXTURE WITH HEAT TO DRYNESS AND THEREAFTER WASHING AND FILTERING TO RECOVER THE SILICA PRODUCT FREE FROM ALUMINUM SULFATE.