Process for preparing alumina sols

Claim 1

IN A PROCESS FOR THE MANUFACTURE OF A STABLE AQUEOUS DISPERSION OF COLLOIDAL, AMORPHOUS, HYDRATED ALUMINA, THE STEPS COMPRISING REACTING A WATER SOLUBLE ALUMINATE SALT OF A BASE HAVING A BASIC DISSOCIATION CONSTANT GREATER THAN ABOUT 0.1 WITH AN ACIDIC COMPONENT OF THE GROUP CONSISTING OF A MONOBASIC ACID HAVING A DISSOCIATION CONSTANT GREATER THAN ABOUT 0.1, AN ALUMINUM SALT OF SUCH ACID, AND MIXTURES THEREOF, THE REACTION BEING EFFECTED BY BRINGING TOGETHER AN AQUEOUS SOLUTION OF THE ALUMINATE AND AN AQUEOUS SOLUTION CONTAINING THE ACID COMPONENT WITH AGITATION AT THE POINT OF INITIAL CONTACT OF SAID AQUEOUS SOLUTIONS TO FORM AN AQUEOUS REACTING MASS, THE ACIDIC COMPONENT BEING PRESENT IN SUCH EXCESS THAT THE PH OF THE REACTING MASS IS BELOW ABOUT 5.5 THROUGHOUT THE REACTION AND IS ABOVE 3.5 AT THE COMPLETION OF THE REACTION, AT LEAST 1/2 OF THE ALUMINUM CONTENT OF THE ALUMINA IN THE AQUEOUS MASS AT THE COMPLETION OF THE REACTION BEING PROVIDED BY ALUMINATE WHICH IS ADDED WHILE THE PH OF THE REACTING MASS IS WITHIN THE RANGE OF ABOUT 3.5 TO 5.5, AND SUFFICIENT WATER BEING PRESENT AT THE COMPLETION OF THE REACTION TO PROVIDE NOT MORE THAN ABOUT 5% BY WEIGHT, CALCULATED AS AL2O3, OF ALUMINUM-CONTAINING MATERIAL IN THE AQUEOUS DISPERSION FORMED IN THE PROCESS.