Process of recovering valuable components from red mud

Claim 1

A METHOD OF TREATING RED MUD TO RECOVER THEREFROM SODIUM AS SODIUM BISULFITE, IRON AS FERRIC OXIDE, TITANIUM AS TITANIUM DIOXIDE, SILICON AS SILICA AND ALUMINUM AS ALUMINA COMPRISING ADDING WATER TO SAID RED MUD TO FORM A SLURRY HAVING A RED MUD CONCENTRATION NO GREATER THAN 40% BY WEIGHT, CONTACTING THE SLURRY WITH SULFUR DIOXIDE TO ABSORB THE SULFUR DIOXIDE INTO THE SLURRY UNTIL THE PH OF THE SLURRY IS AT A VALUE OF FROM 3.5 TO 6 TO DISSOLVE SODIUM OXIDE CONTAINED IN THE RED MUD OUT OF THE RED MUD INTO THE WATER TO FORM A SOLUTION OF SODIUM BISULFIDE, SEPARATING SAID SOLUTION FROM AN INSOLUBLE RESIDUE OF THE RED MUD, ADDING WATER TO THE INSOLUBLE RESIDUE TO FORM AN AQUEOUS SUSPENSION THEREOF, CONTACTING THE SUSPENSION WITH SULFUR DIOXIDE TO ABSORB THE SULFUR DIOXIDE INTO THE SUSPENSION UNTIL THE PH OF THE SUSPENSION IS AT A VALUE OF FROM 1.5 TO 2.5 TO DISSOLVE ALUMINA AND SILICA CONTAINED IN THE RED MUD RESIDUE OUT OF THE RESIDUE INTO THE WATER TO FORM A SOLUTION OF ALUMINUM BISULFITE AND SILICA AND TO LEAVE IN AN UNDISSOLVED STATE FERRIC OXIDE AND TITANIUM DIOXIDE INITIALLY CONTAINED IN THE RED MUD, SEPARATING THE LAST MENTIONED SOLUTION FROM AN INSOLUBLE RESIDUE OF THE FIRST MENTIONED INSOLUBLE RESIDUE, HEATING THE LAST MENTIONED SOLUTION TO DRIVE SOME OF THE SULFUR DIOXIDE THEREFROM TO ADJUST THE PH THEREOF TO A VALUE OF FROM 2.5 TO 3 WHEREBY THE SILICA PRECIPITATES THEREFROM, LEAVING A RESIDUAL SOLUTION, HEATING THE RESIDUAL SOLUTION TO DRIVE SOME OF THE SULFUR DIOXIDE THEREFROM TO ADJUST THE PH THEREOF TO A VALUE ABOVE 3.5 WHEREBY ALUMINUM BISULFITE PRECIPITATES THEREFROM, AND CALCINING THE ALUMINUM BISULFITE AT A TEMPERATURE OF FROM 500 TO 700*C. TO DECOMPOSE THE ALUMINUM BISULFITE INTO ALUMINA.

Claim 2

A METHOD OF TREATING RED MUD TO RECOVER THEREFROM SODIUM AS SODIUM BISULFITE, IRON AS FERRIC OXIDE, TITANIUM AS TITANIUM DIOXIDE, SILICON AS SILICA AND ALUMINUM AS ALUMINA COMPRISING ADDING WATER TO SAID RED MUD TO FORM A SLURRY HAVING A RED MUD CONCENTRATION NO GREATER THAN 40% BY WEIGHT, CONTACTING THE SLURRY WITH SULFUR DIOXIDE TO ABSORB THE SULFUR DIOXIDE INTO THE SLURRY UNTIL THE PH OF THE SLURRY IS AT A VALUE OF FROM 3.5 TO 6 TO DISSOLVE SODIUM OXIDE CONTAINED IN THE RED MUD OUT OF THE RED MUD INTO THE WATER TO FORM A SOLUTION OF SODIUM BISULFIDE, SEPARATING SAID SOLUTION FROM AN INSOLUBLE RESIDUE OF THE RED MUD, ADDING WATER TO THE INSOLUBLE RESIDUE TO FORM AN AQUEOUS SUSPENSION THEREOF, CONTACTING THE SUSPENSION WITH SULFUR DIOXIDE TO ABSORB THE SULFUR DIOXIDE INTO THE SUSPENSION UNTIL THE PH OF THE SUSPENSION IS AT A VALUE OF FROM 1.5 TO 2.5 TO DISSOLVE ALUMINA AND SILICA CONTAINED IN THE RED MUD RESIDUE OUT OF THE RESIDUE INTO THE WATER TO FORM A SOLUTION OF ALUMINUM BISULFITE AND SILICA AND TO LEAVE IN AN UNDISSOLVED STATE FERRIC OXIDE AND TITANIUM DIOXIDE INITIALLY CONTAINED IN THE RED MUD, SEPARATING THE LAST MENTIONED SOLUTION FROM AN INSOLUBLE RESIDUE OF THE FIRST MENTIONED INSOLUBLE RESIDUE, HEATING THE LAST MENTIONED SOLUTION TO DRIVE SOME OF THE SULFUR DIOXIDE THEREFROM TO ADJUST THE PH THEREOF TO A VALUE OF FROM 2.5 TO 3 WHEREBY THE SILICA PRECIPITATES THEREFROM, LEAVING A RESIDUAL SOLUTION, HEATING THE RESIDUAL SOLUTION TO DRIVE SOME OF THE SULFUR DIOXIDE THEREFROM TO ADJUST THE PH THEREOF TO A VALUE ABOVE 3.5 WHEREBY ALUMINUM BISULFITE PRECIPITATES THEREFROM, AND CALCINING THE ALUMINUM BISULFITE AT A TEMPERATURE OF FROM 500 TO 700*C. TO DECOMPOSE THE ALUMINUM BISULFITE INTO ALUMINA.