Cyclic process for recovering vanillin and sodium values from lignosulfonic waste liquors by ion exchange

Claim 1

A REPETITIVE CYCLIC PROCESS FOR RECOVERING SODIUM VALUES FROM AND FOR A LPROCESS FOR PRODUCING VANILLIN FROM LIGNOSULFONIC ACID COMPOUNDS, WHICH COMPRISES: (1) PULPING LIGNOCELLULOSE MATERIALS UTILIZING A SODIUM BASE SULPHITE PULPING PROCESS TO PRODUCE LIGNOSULFONIC ACID COMPOUNDS IN THE LIQUOR RESIDUAL FROM SAID SULPHITE PULPING PROCESS; (2) OXIDIZING SAID LIGNOSULFONIC ACID COMPOUNDS UNDER ALKALINE CONDITIONS IN THE PRESENCE OF SODIUM HYDROXIDE, SAID SODIUM HYDROXIDE BEING PRESENT IN SOLUTION WITH SAID LIGNOSULFONIC ACID COMPOUNDS, TO PRODUCE VANILLIN IN THE FORM OF ITS SODIUM DERIVATIVE IN THE LIQUOR RESIDUAL FROM SAID OXIDIZING STEP, SAID LIQUOR RESIDUAL FROM SAID OXIDIZING STEP CONTAINING LIGNIN IN SOLUTION; (3) PASSING SAID LIQUOR RESIDUAL FROM SAID OXIDIZING STEP THROUGH A CATION EXCHANGE RESIN HAVING EXCHANGE CENTRES SELECTED FROM AT LEAST ONE OF THE GROUP CONSISTING OF CARBOXYLIC AND PHOSPHORIC ACID EXCHANGE CENTRES, WHICH RESIN IS FURTHER CHARACTERIZED BY ITS ABILITY TO BE REGENERATED UNDER ATMOSPHERIC PRESSURE TO ITS HYDROGEN FORM BY AN ACID SELECTED FROM THE GROUP CONSISTING OF SULPHUROUS ACID, AQUEOUS SOLUTIONS OF SODIUM BISULPHITE, AND MIXTURES OF SAME, SAID LIQUOR RESIDUAL FROM SAID OXIDIZING STEP CONTAINING LIGNIN IN SOLUTION AND BEING PASSED THROUGH SAID RESIN AT A RATE WHICH MAINTAING THE PH OF SAID LIQUOR HIGHER THAN THAT AT WHICH LIGNIN PRECIPITATES THEREIN TO CONVERT SAID RESIN TO ITS SODIUM FORM; (4) PASSING AN ACID SELECTED FROM THE GROUP CONSISTING OF SULPHUROUS ACID, AQUEOUS SOLUTIONS OF SODIUM BISULPHITE, AND MIXTURES OF THE SAME THROUGH SAID RESIN IN ITS SODIUM FORM TO REGENERATE SAID RESIN TO ITS HYDROGEN FORM AND TO PRODUCE A LIQUOR CONTAINING SODIUM SULPHITE AND SODIUM BISULPHITE; AND (5) RECYCLING SAID LIQUOR CONTAINING SODIUM SULPHITE AND SODIUM BISULPHITE TO SAID SODIUM BASE SULPHITE PULPING PROCESS.