Process for producing a granular material from a solution and/or suspension

Claim 1

A PROCESS FOR PRODUCING A PRODUCT GRANULAR MATERIAL COMPRISING THE STEPS OF: A. FORMING A FLUIDIZED BED OF BED GRANULAR MATERIAL BY PASSING A STREAM OF GAS UPWARDS THROUGH THE BED TO MAINTAIN THE BED BRANULAR MATERIAL IN A FLUIDIZED STATE, SAID GAS BEING SUFFICIENTLY HOT TO EVAPORATE LIQUID IN THE BED AND HAVING A TEMPERATURE LOWER THAN THAT WHICH WILL HEAT DAMAGE THE MATERIAL BEING GRANULATED; B. DISPERSING ONTO THE FLUIDIZED BED AT FLUENT MATERIAL TAKEN FROM THE GROUP CONSISTING (1) A SOLUTION OF THE MATERIAL TO BE GRANULATED, (2) A SUSPENSION OF THE MATERIAL TO BE GRANULATED, (3) A MIXTURE OF SUCH A SOLUTION AND SUSPENSION, (4) DRYY GRANULES OF MATERIAL TO BE GRANULATED (5) A SOLUTION OF THE MATERIAL TO BE GRANULATED PLUS A BINDER; (6) A SUSPENSION OF THE MATERIAL TO BE GRANULATED PLUS A BINDER; (7) A MIXTURE OF SUCH A SOLUTION AND SUSPENSION PLUS A BINDER; AND (8) DRY GRANULES OF MATERIAL TO BE GRANULATED PLUS A BINDER; C. CONTROLLING SAID DISPERSING OF THE FLUENT MATERIAL ONTO THE BED AND THE TEMPERATURE OF THE GAS FLOWING UPWARDS THROUGH THE BED SO THAT THE TEMPERATURE DROP IN THE VERTICAL DIRECTION ACROSS THE BED FROM A POINT SLIGHTLY ABOVE THE BOTTOM OF THE BED TO A POINT JUST ABOVE THE POINT FROM WHICH THE FLUENT MATERIAL IS DISPERSED IS NOT LESS THAN 4*C AND NOT MORE THAN 16*C AND ANY LIQUID IN THE BED IS EVAPORATED; D. WITHDRAWING FROM THE BED A GRANULAR MATERIAL WHICH, IN THE INITIAL STAGES OF THE PROCESS, IS A MIXTURE OF THE BED GRANULAR MATERIAL AND THE PRODUCT GRANULAR MATERIAL, AND AS THE PROCESS CONTINUES, CONTAINS LESS OF THE BED GRANULAR MATERIAL AND MORE OF THE PRODUCT GRANULAR MATERIAL; E. SCREENING THE WITHDRAWN GRANULAR MATEIT INTO SELECTED SIZES; F. RECYCLING TO THE BED PART OF THE WITHDRAWN GRANULAR MATERIAL INCLUDING ALL OF THE FINE FRACTIONS HAVING A GRANULAR SIZE SMALLER THAN 0.15 MM AS WELL AS A PORTION OF THE COARSE FRACTIONS HAVING A GRANULAR SIZE GREATER THAN 0.0.15 MM, THE BALANCE OF THE COARSE FRACTIONS BEING WITHDRAWN FROM THE PROCESS AS THE GRANULAR MATERIAL TO BE PRODUCED; AND G. CONTROLLING THE WITHDRAWAL OF GRANULAR MATERIAL FROM THE BED AND THE WEIGHT OF WITHDRAWN MATERIAL WHICH IS RECYCLED SO THAT THE PRESSURE DROP IN THE VERTICAL DIRECTION ACROSS THE BED BETWEEN SUBSTANTIALLY THE SAME POINTS AS THE TEMPERATURE DROP DOES NOT FLL BELOW 56 MM WATER COLUMN AND DOES NOT RISE ABOVE 150 MM WATER COLUMN, WHEREBY IN THE GRANULAR MATERIAL WITHDRAWN FROM THE BED AT LEAST 20% OF THE GRANULES HAVE A GRANULE SIZE FROM 0.15 TO 2 MM.