Production of boric acid and anhydrous sodium sulfate

Claim 1

IN A CYCLIC PROCESS FOR PRODUCING ANHYDROUS SODIUM SULFATE AND BORIC ACID, WHICH PROCESS INCLUDES THE STEPS OF DISSOLVING SODIUM BORATE IN A MOTHER LIQUOR, ADDING SULFURIC ACID TO THE RESULTING SOLUTION TO FORM SODIUM SULFATE AND BORIC ACID, PRECIPITATING ANHYDROUS SODIUM SULFATE AT A RELATIVELY ELEVATED TEMPERATURE, REMOVING THE PRECIPITATED SODIUM SULFATE, PRECIPITATING BORIC ACID FROM THE RESULTING SOLUTION AT A RELATIVELY LOWER TEMPERATURE AND RETURNING THE REMAINING SOLUTION AS MOTHER LIQUOR TO REPEAT THE CYCLE; THE METHOD OF CARRYING THE STEP OF ANHYDROUS SODIUM SULFATE PRECIPITATION TO SUBSTANTIAL COMPLETION IN THE PRESENCE OF A SUBSTANCE TENDING TO STABILIZE SUPERSATURATION OF ANHYDROUS SODIUM SULFATE, SAID METHOD COMPRISING DISSOLVING SOLID SODIUM SULFATE IN THE RECYCLED MOTHER LIQUOR AFTER THE STEP OF REMOVING THE BORIC ACID PRECIPITATED DURING ONE CYCLE AND BEFORE COMPLETION OF THE SAID TREATMENT WITH SULFURIC ACID DURING THE SUBSEQUENT CYCLE AND AT A TEMPERATURE APPRECIABLY LOWER THAN THE SAID ELEVATED TEMPERATURE, THEN COMPLETING THE SAID TREATMENT WITH SULFURIC ACID AND RAISING THE TEMPERATURE OF THE SOLUTION TO THE SAID ELEVATED TEMPERATURE, THEREBY PRECIPITATING A QUANTITY OF ANHYDROUS SODIUM SULFATE CORRESPONDING TO THE SUM OF THE SODIUM SULFATE DISSOLVED FROM SOLID FORM AND THE SODIUM SULFATE FORMED IN SOLUTION BY THE SAID ACID TREATMENT.