Dry dust freeing of coals and similar materials

Claim 1

A DRY PROCESS FOR DEDUSTING COALS AND SIMILAR MATERIALS, COMPRISING MAINTAINING IN A FIRST VERTICALLY EXTENDING CONFINED PATH AN UPWARDLY FLOWING GASEOUS FLUID CURRENT, DELIVERING TO THE UPPER PORTION OF SAID FIRST FLUID PATH TO PASS DOWNWARDLY LENGTHWISE THEREOF THE STARTING MIXTURE OF GAIN SIZED PARTICLES AND FINE AND VERY FINE SMALL SIZED PARTICLES SO THAT THE FINE AND MOST OF THE VERY FINE SMALL SIZED PARTICLES WILL BE SEPARATED FROM THE FALLING GRAIN SIZED PARTICLES BY THE FIRST RISING FLUID CURRENT, MAINTAINING IN A SECOND VERTICALLY EXTENDING CONFINED PATH AN UPWARDLY FLOWING GASEOUS FLUID CURRENT, DELIVERING TO AN INTERMEDIATE PORTION OF SAID SECOND FLUID PATH TO PASS DOWNWARDLY LENGTHWISE OF THE REMAINDER THEREOF THE PARTIALLY DEDUSTED GRAIN SIZED PARTICLES THAT REACH THE LOWER END PORTION OF THE SAID FIRST FLUID PATH SO THAT THE REMAINING VERY FINE SMALL SIZED PARTICLES WILL BE SEPARATED FROM THE FALLING GRAIN SIZED PARTICLES BY THE SECOND RISING FLUID CURRENT, PARTIALLY EXPANDING THE FLUID CURRENT LEAVING THE UPPER PORTION OF THE FIRST FLUID PATH TO SEPARATE THEREFROM MOST OF THE FINE SMALL SIZED PARTICLES SUSPENDED THEREIN, DELIVERING THE THUS SEPARATED FINE SMALL SIZED PARTICLES TO AN INTERMEDIATE PORTION OF SAID SECOND FLUID PATH TO CAUSE THE FLUID CURRENT RISING THEREIN TO SEPARATE AND CARRY UPWARDLY ANY VERY FINE SMALL SIZED PARTICLES STILL REMAINING WITH SAID FINE PARTICLES AND TO PERMIT SAID FINE PARTICLES TO FALL DOWNWARDLY THEROGH THE REMAINDER OF THE SECOND FLUID PATH FOR DISCHARGE FROM THE BOTTOM THEREOF WITH THE DEDUSTED GRAIN SIZED PARTICLES, DELIVERING TO THE UPPER PORTION OF THE SECOND FLUID PATH THE PARTIALLY EXPANDED FLUID CURRENT FROM THE FIRST FLUID PATH SO THAT THE TWO FLUID CURRENTS WILL MIX, PARTIALLY EXPANDING THE MIXED FLUID CURRENTS LEAVING THE UPPER PORTION OF THE SECOND FLUID PATH TO SEPARATE THEREFROM THE FINE SMALL SIZED PARTICLES SUSPENDED THEREIN, AND FINALLY SEPARATING FROM THE PARTIALLY EXPANDED, MIXED FLUID CURRENTS THE SMALL SIZED PARTICLES STILL SUSPENDED THEREIN.