Process for recovering iodides from aqueous solutions by ion exchange and conversion of the iodides to iodine

Claim 1

IN A PROCESS FOR SEPARATING AND RECOVERING IODIDE IONS AS IODINE FROM AN AQUEOUS SOLUTION WHEREIN A BRINE CONTAINING IODIDE IONS IS BROUGHT INTO CONTACT WITH A QUATERNARY AMMONIUM ANION EXCHANGE RESIN AND THE IODIDE IONS ARE ADSORBED ON THE RESIN, AND WHEREIN THE ABSORBED IODIDE IONS ARE ELUTED FROM THE RESIN AND SUBSEQUENTLY CONVERTED TO IODINE, THE IMPROVEMENT WHICH CONSISTS IN ELUTING THE ADSORBED IODIDE IONS FROM THE RESIN BY WASHING THE ANION EXCHANGE RESIN CONTAINING THE ADSORBED IODIDE IONS WITH AN AQUEOUS ACIDIC SOLUTION HAVING A PH BETWEEN 2 AND 3 AND CONTAINING AN ALKALI METAL HALIDE SALT OF THE GROUP CONSISTING OF CHLORIDE AND BROMIDE, IN A CONCENTRATION BETWEEN 5 PERCENT BY WEIGHT AND THAT OF A SUBSTANTIALLY SATURATED SOLUTION AND FROM ABOUT 10 TO ABOUT 50 PARTS BY WEIGHT OF SULFUR DIOXIDE PER MILLION PARTS BY WEIGHT OF THE SOLUTION AND COLLECTING EFFLUENT LIQUID CONTAINING THE DISPLACED IODIDE IONS.