Preparation of ammonium metavanadate

Claim 1

A PROCESS FOR PRODUCING ANNONIUM METAVANADATE COMPRISING ADDING TO AN ACIDIC VANADYL SOLUTION HAVING A PH LESS THAN ABOUT 1.0 AND CONTAINING AT LEAST ONE OF THE IMPURITIES SELECTED FROM THE GROUP CONSISTING OF IRON, ALUMINA, PHOSPHATES AND ARSENATES AN AMOUNT OF SODIUM CHLORIDE AT LEAST SUFFICIENT TO OXIDIZE THE VANADIUM IN THE ACIDIC VANADYL SOLUTION TO THE PENTAVALENT STATE; PREPARING A SECOND AQUEOUS SOLUTION OF SODIUM CARBONATE AND ADDING AMMONIA THERETO; ADDING SAID OXIDIZED ACIDIC VANADIUM SOLUTION TO SAID SECOND AQUEOUS SOLUTION OF SODIUM CARBONATE TO WHICH AMMONIA HAS BEEN ADDED, THE TOTAL AMOUNT OF SODIUM CARBONBATE IN SAID SECOND AQUEOUS SOLUTION AND AMMONIUM ADDED TO SAID SECOND AQUEOUS SOLUTION BEING SUFFICIENT TO ADJUST THE PH OF THE RESULTING MIXTURE TO AND MAINTAIN THE PH OF THE RESULTING MIXTURE AT ABOUT 7.0 TO 8.0 AND THE TOTAL AMOUNT OF AMMONIUM ADDED TO SAID MIXTURE BEING AMOUNTS SUFFICIENT TO PROVIDE LESS THAN 55 PERCENT OF THE TOTAL NEUTRALIZING EFFECT OF SODIUM CARBONATE PLUS AMMONIA REQUIRED TO MAINTAIN THE PH OF SAID RESULTING MIXTURE BETWEEN ABOUT 7.0 AND 8.0; DIGESTING THE SOLUTIONN AT A TEMPERATURE RANGING FROM 70 TO 90 DEGREES CENTIGRADE FOR A PERIOD OF TIME SUFFICIENT TO ALLOW PRECIPITATION OF IMPURITIES IN A FILTERABLE FORM WHILE SUSTAINING PENTAVALENT VANADIUM IN SOLUTION; FILTERING THE IMPURITIES FROM A MIXTURE; ADDING AMMONIUM CHLORIDE IN AMOUNTS SUFFICIENT TO CAUSE PRECIPITATION OF AMMONIUM METAVANADATE; AND REMOVING THE AMMONIUM METAVANADATE FROM THE MIXTURE.