Method for wet milling rutile pigment

Claim 1

IN A PROCESS FOR MAKING TI02 PIGMENT FROM A TI02 CALCINER DISCHARGE CONTAINING OCCLUDED WATER SOLUBLE METAL SULFATES IN AN AMOUNT FROM 0.3% TO 1.0% CALCULATED AS SULFURIC OXIDES ON A TI02 WEIGHT BASIS WHEREIN THE CALCINED TI02 CALCINER DISCHARGE IS WET MILLED, THE IMPROVEMENT COMPRISING THE STEPS OF: WASHING THE T102 CALCINER DISCHARGE WITH WATER PRIOR TO WET NMILLING SUFFICIENTLY TO REDUCE THE OCCLUDED WATER SOLUBLE METAL SULFATES IN SAID TIO2 CALCINER DISCHARGE TO AN AMOUNT NO MORE THAN 25% CALCULATED AS SUFLURIC OXIDES ON A TI02 WEIGHT BASIS, AND THEN WET MILLING THE WASHED TI02 CALCINER DISCHARGE IN THE PRESENCE OF A DISPERSING AGENT SELECTED FROM THE GROUP CONSISTING OF SODIUM HYDROXIDE, SODIUM SILICATE, SODIUM PHOSPHATE, AMINOMETHYL PROPANOL, MONOISOPROPANOLAMINE AMD MIXTURES THEREOF.