Process for producing fluoride containing compounds by reaction of boric acid and alkali metal silicofluoride

Claim 1

PROCESS FOR THE PREPARATION OF ALKALI METAL ALUMINUM FLUORIDES WHICH COMPRISES CONTINUOUSLY SCRUBBING A GAS CONTAINING SILICON TETRAFLUORIDE AND PHOSPHORIC ACID WITH A WATER SOLUTION OF PHOSPHORIC ACID THEREBY PRODUCING A SLURRY CONTAINING SAID PHOSPHORIC ACID AND HYDROFLUOSILICIC ACID IN SOLUTION AND SILICA IN SOLID FORM, FILTERING SAID SLURRY TO SEPARATE SAID SILICA FROM A FILTRATE CONTAINING SAID PHOSPHORIC ACID AND HYDROFLUOSILICIC ACID, AT LEAST PARTIALLY NEUTRALIZING SAID FILTRATE BY THE ADDITION THERETO OF AN ALKALIEN ALKALI METAL COMPOUND THEREBY FORMING A SLURRY CONTAINING ALKALI METAL SILICONFLUORIDE IN SOLID FORM AND PHOSPHORIC ACID IN SOLUTION, FILTERING THE LAST NAMED SLURRY TO SEPARATE SAID ALKALI METAL SILICONFLUORIDE FROM A FILTRATE CONTAINING SAID PHOSPHORIC ACID, RETURNING THE LAST-NAMED FILTRATE TO SAID SCRUBBING STEP, CONTINUOUSLY SCRUBBING A SECOND GAS CONTAINING SILICON TETRAFLUORIDE WHICH IS FREE OF PHOSPHORIC ACID WITH AN AQUEOUS SOLUTION OF BORIC ACID TO FORM A SLURRY CONTAINING SILICA, FLUOBORIC ACID, BORIC ACID AND WATER, MIXING THE LAST-NAMED SLURRY WITH THE ABOVE-NAMED SEPARATED ALAKLI METAL SILICOFLUROIDE THEREBY PRODUCING A SLURRY CONTAINING SILICA IN SOLID FORM AND ALKALI METAL FLUORIDE, ALKALI METAL FLUOBORATE AND FLUOBORIC ACID IN SOLUTION, FILTERIGN THE LAST-NAMED SLURRY TO SEPARATE SILICA FROM A FILTRATE, MIXIGN THE LAST-NAMED FILTRATE WITH ALUMINUM HYDROXIDE AND AN ALKALINE ALKALI METAL COMPOUND THEREBY PRODUCING A SLURRY CONTAINING AN ALKALI METAL ALUMINUM FLUORIDE IN SOLID FORM AND BORIC ACID IN SOLUTION, FILTERING SAID LAST-NAMED SLURRY TO SEPARATE SAID ALKALI METAL ALUMINUM FLUORIDE FROM A FILTRATE AND RETURNING THE LAST-NAMED FILTRATE TO THE SECOND-NAMED SCRUBBING STEP.