Process for the purification of crystals

Claim 1

IN A PROCESS WHICH COMPRISES PASSING A SLURRY OF CRYSTALS IN MOTHER LIQUOR INTO A FILTER ZONE, WITHDRAWING MOTHER LIQUOR FROM SAID FILTER ZONE, MOVING THE RESULTING CRYSTAL MASS INTO A PURIFICATION ZONE, MOVING SAID CRYSTAL MASS THROUGH SAID PURIFICATION ZONE INTO A MELTING ZONE, MELTING CRYSTALS IN SAID MELTING ZONE, PASSING A PORTION OF THE RESULTING MELT COUNTERCURRENTLY TO THE DIRECTION OF MOVEMENT OF CRYSTALS IN SAID PURIFICATION ZONE, AND RECOVERING A PRODUCT FROM SAID MELTING ZONE, THE IMPROVEMENT IN STARTING UP SAID PROCESS WHICH COMPRISES INTRODUCING SAID SLURRY OF CRYSTALS IN MOTHER LIQUOR INTO SAID FILTER ZONE, FLOWING SAID SLURRY THROUGH SAID FILTER ZONE AND SAID PURIFICATION ZONE TOWARD SAID MELTING ZONE, OBSTRUCTING THE FLOW OF CRYSTALS IN A PORTION OF SAID PURIFICATION ZONE ADJACENT SAID MELTING ZONE WHILE ALLOWING MOTHER LIQUOR TO FLOW THROUGH SAID PORTION OF SAID PURIFICATION ZONE, THEREBY FORMING A CRYSTAL BED IN SAID PURIFICATION ZONE UPSTREAM CRYSTALWISE FROM SAID MELTING ZONE, RECOVERING MOTHER LIQUOR FROM SAID MELTING ZONE, AND AFTER FORMATION OF SAID CRYSTAL BED WITHIN SAID PURIFICATION ZONE EFFECTING THE ABOVE-ENUMERATED STEPS OF SAID PROCESS.