Process for removing iron from acidic aluminum-containing solutions

Claim 1

A PROCESS FOR REMOVING FERRIC IRON FROM AN ACIDIC SOLUTION, COMPRISING THE STEPS OF (A) CONTACTING AN ACIDIC SOLUTION, HAVING A PH BETWEEN 1 AND 2, OF ALUMINUM NITRATE OR ALUMINUM SULFATE IN THE FORM OF AN AQUEOUS PHASE CONTAINING IRON VALUES IN THE FORM OF FERRIC IRON WITH A CATIONEXCHANGE LIQUID EXTRACTANT IN THE FORM OF AN ORGANIC PHASE THEREBY TO FORM AN IRON COMPLEX OF SAID EXTRACTANT AND TO TRANSFER SAID FERRIC IRON FROM SAID AQUEOUS PHASE TO SAID ORGANIC PHASE; SAID EXTRACTANT BEING CHARACTERIZED AS BEING AN ALKYL-SUBSTITUTED PHOSPHORIC ACID HAVING THE FORMULA HRR''PO4 WHEREIN R IS ALKYL CONTAINING AT LEAST 8 CARBON ATOMS AND R'' IS HYDROGEN OR ALKYL, BEING ESSENTIALLY INSOLUBLE IN SAID AQUEOUS PHASE, BEING CAPABLE OF COMPLEXING WITH FERRIC IONS IN SAID ACIDIC SOLUTION, AND BEING ESSENTIALLY NON-COMPLEXING WITH ALUMINUM; THE VOLUME RATIO OF SAID AQUEOUS PHASE TO SAID CATIONEXCHANGE LIQUID EXTRACTANT RANGING BETWEEN ABOUT 3 TO 1 AND 10 TO 1; AND (B) SEPARATING SAID AQUEOUS AND ORGANIC PHASES.