Separation of xylene isomers by solvent extraction

Claim 1

A PROCESS FOR FRACTIONATING A MIXTURE CONTAINING ESSENTIALLY META-XYLENE AND PARA-XYLENE, WHICH PROCESS COMPRISES: EXTRACTING SAID MIXTURE SIMULTANEOUSLY WITH SULFUR DIOXIDE SOLVENT AND AN ORGANIC SOLVENT POSSESSING THE PROPERTIES OF BEING LOW FREEZING, SUBSTANTIALLY INERT AND EXHIBITING LITTLE BONDING CHARACTER UNDER CONDITIONS SUCH THAT ALL OF THE CONTACTING SUBSTANCES ARE MAINTAINED IN THE LIQUID STATE, SAID SOLVENTS BEING AT LEAST PARTIALLY IMMISCIBLE EACH OTHER AND SUBSTANTIALLY CHEMICALLY INERT UNDER THE CONDITIONS OF THE PROCESS, THEREBY FORMING A SULFUR DIOXIDE EXTRACT PHASE WHICH IS SUBSTANTIALLY ENRICHED IN PARA-XYLENE AND AN ORGANIC SOLVENT EXTRACT PHASE WHICH IS SUBSTANTIALLY ENRICHED IN META-XYLENE; SEPARATING SAID EXTRACT PHASES; SEPARATING THE XYLENES DISSOLVED IN THE SEPARATED ORGANIC SOLVENT EXTRACT PHASE FROM SAID ORGANIC SOLVENT; DISSOLVING THE THUS-SEPARATED XYLENES IN SULFUR DIOXIDE; COOLING THE RESULTING SOLUTION AND THEREBY PRODUCING CRYSTALS OF META-XYLENE SUBSTANTIALLY FREE FROM PARAXYLENE; SEPARATING THE META-XYLENE CRYSTALS FROM THE REMAINING SOLUTION; SEPARATING THE XYLENES DISSOLVED IN SAID SULFUR DIOXIDE EXTRACT PHASE FROM SAID SULFUR DIOXIDE; DISSOLVING THE THUSSEPARATED XYLENES IN AN INERT ORGANIC SOLVENT THEREFOR; COOLING THE RESULTING SOLUTION AND THEREBY PRODUCING CRYSTALS OF PARA-XYLENE; AND SEPARATING THE PARA-XYLENE CRYSTALS FROM THE REMAINING SOLUTION.