Process for producing pure boric acid and potassium sulfate

Claim 1

IN A PROCESS FOR THE PREPARATION OF BORIC ACID WHEREIN A POTASSIUM BORATE AND SULFURIC ACID ARE ADDED TO A RECYCLED AQUEOUS SOLUTION CONTAINING DISSOLVED BORIC ACID AND POTASSIUM SULFATE AND ALLOWED TO REACT TO PRODUCE BORIC ACID POTASSIUM SULFATE IN QUANTITIES SUFFICIENT TO PRECIPITATE BORIC ACID AT A TEMPERATURE OF ABOUT 35* C. WHILE SUBSTANTIALLY ALL OF SAID POTASSIUM SULFATE REMAINS IN SOLUTION AND WHEREIN SAID SOLUTION IS HEATED TO A TEMPERATURE SUFFICIENTLY IN EXCESS OF SAID35* C. TO DISSOLVE ALL OF SAID POTASSIUM SULFATE AND SAID BORIC ACID AND SAID SOLUTION IS THEREAFTER ADJUSTED TO ABOUT SAID 35*C. TEMPERATURE TO PRECIPITATE A CROP OF BORIC ACID CRYSTALS ABOUT EQUIVALENT TO THE QUANTITY OF BORIC ACID INTRODUCED BY SAID REACTION WITHOUT PRECIPITATING POTASSIUM SULFATE AND SAID BORIC ACID IS SEPARATED THEREFROM, THE IMPROVEMENTS COMPRISING: HEATING THE MOTHER LIQUOR REMAINING AFTER THE SEPARATION THEREFROM OF SAID BORIC ACID CRYSTALS TO A TEMPERATURE IN EXCESS OF ABOUT 75*C. TO EVAPORATE AT LEAST ABOUT ONE-HALF OF SAID WATER THEREFROM TO EXCEED THE SOLUBILITY OF SAID POTASSIUM SULFATE WITH RESPECT TO SAID LIQUOR AT A TEMPERATURE OF ABOUT 75*C. THEREAFTER COOLING SAID MOTHER LIQUOR TO ABOUT SAID 75*C. TEMPERATURE TO PRECIPITATE A CROP OF POTASSIUM SULFATE CRYSTALS ABOUT EQUIVALENT TO THE QUANTITY OF POTASSIUM SULFATE INTRODUCED BY SAID REACTION, SEPARATING SAID POTASSIUM SULFATE, THEREAFTER ADDING WATER TO SAID MOTHER LIQUOR IN AN AMOUNT SUFFICIENT TO REPLACE THAT LOST DURING SAID PROCESS, WHEREIN TO FORM AN AQUEOUS SOLUTION OF A VOLUME SUBSTANTIALLY EQUAL TO THE SAID RECYCLED AQUEOUS SOLUTION INITIALLY PRESENT, AND RECYCLING THE AQUEOUS SOLUTION SO FORMED IN SAID PROCESS.