Process for the electrolysis of alkali metal halide brines

Claim 1

IN A PROCESS FOR THE COORDINATED OPERATION OF DIAPHRAGM AND MERCURY CELLS FOR THE ELECTROLYSIS OF ALKALI METAL HALIDE BRINES, WHEREIN SALT AND IMPURITY SULFATE RECOVERED FROM THE EVAPORTION OF THE DIAPHRAGM CELL CATHOLYTE IS USED TO SUPPLY SAID MERCORY CELL, THE IMPROVEMENTS COMPRISING: REPULPING SAID SALT WITH PURGE BRINE, WHEREBY A PORTION OF THE SULFATE CONTAINED IN SAID SALT IS TAKEN INTO SOLUTION; WASHING SAID REPULPED SALT WITH DEPLETED BRINE FROM SAID MERCURY CELL, WHEREBY SULFATE CONTENT OF SAID SALT IS FURTHER REDUCED, CHLORATE IN SAID DEPLETED BRINE REMAINING IN SOLUTION; SEPARATING SAID SALT-DEPLETED BRINE MIXTURE INTO A PURGE BRINE FRACTION AND FIRST AND SECOND SALT FRACTIONS, SAID BRINE FRACTION BEING RELATIVELY CONCENTRATED IN SULFATE AND CHLORATE AND SAID SALT FRACTIONS BEING RELATIVELY DEPLETED IN SAID SULFATE AND CHLORATE; PURGING SAID BRINE FRACTION FROM THE SYSTEM, EXCEPT AS REQUIRED FOR USE IN SAID REPULPING; DISSOLVING SAID SECOND SALT FRACTION IN FRESH BRINE FOR ELECTROLYSIS WITHIN SAID DIAPHRAGM CELL, AND DISSOLVING SAID FIRST SALT FRACTION IN DEPLETED BRINE FROM SAID MERCURY CELL FOR ELECTROLYSIS WITHIN SAID MERCURY CELL.