Method for improving brightness of kaolinite clays including iron pyrites

Claim 1

A METHOD FOR PREPARING A BRIGHT COATING KAOLIN FROM A CRUDE KAOLINITIC CLAY, INCLUDING DISCOLORING IRON-BASED CONTAMINANTS IN THE FORM OF IRON PYRITES AND SULFUROUS CONTAMINANTS, COMPRISING: SUBJECTING SAID CRUDE CLAY TO COMMINUTION; ROASTING SAID COMMINUTED CRUDE CLAY IN AN OXIDIZING ATMOSPHERE AT A TEMPERATURE SUFFICIENT TO OXIDIZE THE PYRITES BUT INSUFFICIENT TO DRIVE OFF THE CHEMICALLY BOUND WATER FROM THE KAOLINITE CRYSTALS, SAID TEMPERATURE BEING FROM 400*C TO 600*C, UNTIL A SUBSTANTIAL CESSATION OF SULFUROUS FUMES IS NOTED, TO CONVERT AT LEAST A PORTION OF THE SULFUROUS CONTAMINANTS TO A FORM EXHIBITING INCREASED MAGNETIC SUSCEPTABILITY AND INCREASED SOLUBILITY IN CHEMICAL LEACHANTS SELECTED FROM THE GROUP CONSISTING OF ZINC DITHIONITE, ZINC SALTS OF HYDROSULFUROUS ACID, SODIUM SALTS OF HYDROSULFUROUS ACID AND COMBINATIONS THEREOF; THEREAFTER FORMING AN AQUEOUS SLURRY OF SAID ROASTED CLAY; SUBJECTING AT LEAST A PORTION OF S HAVING AN INTENSITY OF AT LEAST 2.4 KILOGAUSS AND HIGH FIELD GRADIENTS TO SEPARATE AT LEAST PART OF SAID CONVERTED COMPONENTS; AND THEREAFTER SUBJECTING SAID SLURRY TO A LEACHING STEP EMPLOYING ABOUT 1.2 WEIGHT PERCENT LEACH SELECTED FROM THE GROUP CONSISTING OF ZINC DITHIONITE, ZINC SALTS OF HYDROSULFUROUS ACID, SODIUM SALTS OF HYDROSULFUROUS ACID AND COMBINATIONS THEREOF AND TO A FILTRATION STEP.

Claim 2

A METHOD FOR PREPARING A BRIGHT COATING KAOLIN FROM A CRUDE KAOLINITIC CLAY, INCLUDING DISCOLORING IRON-BASED CONTAMINANTS IN THE FORM OF IRON PYRITES AND SULFUROUS CONTAMINANTS, COMPRISING: SUBJECTING SAID CRUDE CLAY TO COMMINUTION; ROASTING SAID COMMINUTED CRUDE CLAY IN AN OXIDIZING ATMOSPHERE AT A TEMPERATURE SUFFICIENT TO OXIDIZE THE PYRITES BUT INSUFFICIENT TO DRIVE OFF THE CHEMICALLY BOUND WATER FROM THE KAOLINITE CRYSTALS, SAID TEMPERATURE BEING FROM 400*C TO 600*C, UNTIL A SUBSTANTIAL CESSATION OF SULFUROUS FUMES IS NOTED, TO CONVERT AT LEAST A PORTION OF THE SULFUROUS CONTAMINANTS TO A FORM EXHIBITING INCREASED MAGNETIC SUSCEPTABILITY AND INCREASED SOLUBILITY IN CHEMICAL LEACHANTS SELECTED FROM THE GROUP CONSISTING OF ZINC DITHIONITE, ZINC SALTS OF HYDROSULFUROUS ACID, SODIUM SALTS OF HYDROSULFUROUS ACID AND COMBINATIONS THEREOF; THEREAFTER FORMING AN AQUEOUS SLURRY OF SAID ROASTED CLAY; SUBJECTING AT LEAST A PORTION OF S HAVING AN INTENSITY OF AT LEAST 2.4 KILOGAUSS AND HIGH FIELD GRADIENTS TO SEPARATE AT LEAST PART OF SAID CONVERTED COMPONENTS; AND THEREAFTER SUBJECTING SAID SLURRY TO A LEACHING STEP EMPLOYING ABOUT 1.2 WEIGHT PERCENT LEACH SELECTED FROM THE GROUP CONSISTING OF ZINC DITHIONITE, ZINC SALTS OF HYDROSULFUROUS ACID, SODIUM SALTS OF HYDROSULFUROUS ACID AND COMBINATIONS THEREOF AND TO A FILTRATION STEP.