Method of and apparatus for drying particulate material

Claim 1

A METHOD OF DRYING MOIST CRYSTALLINE SALT PARTICLES WHICH COMPRISES THE STEPS OF (1) INTRODUCING SAID PARTICLES INTO A FIRST BED IN A DRYING ZONE, (2) URGING A STREAM OF DRYING GAS AT A GIVEN SUPERATMOSPHERIC PRESSURE AGAINST THE BOTTOM OF SAID FIRST BED TO FLUIDIZE THE PARTICLES THEREIN, (3) WITH DRAWING DRIED NOT PARTICLES FROM THE BOTTOM OF SAID FIRST BED AND INTRODUCING THE DRIED HOT PARTICLES INTO A SECOND BED IN A COOLING ZONE, (4) DRAWING A STREAM OF COOLING GAS AT SUBATMOSPHERIC PRESSURE UPWARDLY THROUGH SAID SECOND BED TO FLUIDIZED THE PARTICLES THEREIN, AND (5) WITHDRAWING THE STREAM OF COOLING GAS FROM THE COOLING ZONE, INCREASING THE PRESSURE IN THE STREAM TO SUPERATMOSPHERIC PRESSURE AND HEATING THE GAS IN THE STREAM, AND THEN INTRODUCING THE STREAM INTO THE DRYING ZONE FOR CARRYING OUT STEP (2), WHEREBY STEP (3) IS CARRIED OUT BY REMOVING PARTICLES FROM A ZONE UNDER SUPERATMOSPHERIC PRESSURE TO A ZONE UNDER SUBATMOSPHERIC PRESURE.