Sulfite waste treatment process

Claim 1

IN THE CYCLICAL METHOD OF MAKING SUBSTANTIALLY CALCIUM-FREE MAGNESIA AND PULP BY THE DIGESTION OF A CELLULOSIC FIBROUS MATERIAL IN A COOKING LIQUOR OF MAGNESIUM AND CALCIUM BISULPHITES, AND SEPARATING THE PULP THEREFROM, THE STEPS OF NEUTRALIZING WASTE LIQUOR FROM THE DIGESTION BY THE ADDITION OF DOLOMITE TO PRECIPITATE A PORTION OF THE CALCIUM AS CALCIUM SULFITE, SEPARATING THE THUS FORMED PRECIPITATE FORM THE WASTE LIQUOR TO FORM A SOLUTION RICH IN MAGNESIUM SALTS, DELIVERING THE PRECIPITATE TO A SULFUR DIOXIDE ABSORPTION TOWER FOR CONTACT WITH SULFUR DIOXIDE TO FORM THE CORRESPONDING BISULFITE, RECYCLING THE LATTER TO THE DIGESTION STEP, ADDING BURNED DOLOMITE TO THE SOLUTION RICH IN MAGNESIUM SALTS IN AN AMOUNT WHEREBY THE MAGNESIUM IONS THEREIN EXCEED THE CALCIUM IONS, ADDING CALCIUM SULPHATE TO THE SOLUTION RICH IN MAGNESIUM TO REPLACE SULFUR LOSSES FROM THE SYSTEM, CARBONATING THE SOLUTION TO PRECIPITATE CALCIUM THEREFROM AS CALCIUM CARBONATE, SEPARATING THE PRECIPITATED CALCIUM CARBONATE FROM THE SOLUTION RICH IN MAGNESIUM SALTS, FORM A SUBSTANTIALLY CALCIUM FREE SOLUTION OF TO MAGNESIUM SALTS, DISCARDING THE PRECIPITATED CALCIUM CARBONATE FROM THE SYSTEM, CONCENTRATING THE CALCIUM-FREE SOLUTION, IGNITING THE CONCENTRATED SOLUTION TO LIBERATE SULFUR DIOXIDE AND FORM MAGNESIA, RECYCLING THE LIBERATED SULFUR DIOXIDE TO THE ABSORPTION TOWER, AND INTRODUCING AN AQUEOUS SUSPENSION OF DOLOMITE INTO THE ABSORPTION TOWER TO REPLACE MATERIALS DISCARDED FROM THE SYSTEM.