Process and apparatus for the sorting of two or more materials

Claim 1

APPARATUS FOR ACHIEVING VERY ACCURATE SORTING OF PARTICULATE MATERIALS IN A FLUID FLOW, COMPRISING A LOWER INCLINED DUCT PORTION, A VERTICAL DUCT PORTION OF GIVEN HEIGHT CONNECTED AT ITS LOWER END TO THE UPPER END OF SAID LOWER DUCT PORTION TO FORM A CONTINUOUS DUCT, MEANS FOR FEEDING SORTING FLUID INTO THE LOWER END OF SAID LOWER INCLINED DUCT PORTION AND UP THROUGH SAID INCLINED AND VERTICAL PORTIONS, AND FOR FEEDING THE PARTICULATE MATERIAL TO BE SORTED INTO THE SORTING FLUID AT AN INTERMEDIATE ZONE THEREOF LOCATED AT THE JUNCTURE OF SAID INCLINED AND VERTICAL DUCT PORTIONS, MEANS AT THE UPPER END OF SAID VERTICAL DUCT PORTION FOR DISCHARGING THE SORTING FLUID FLOWING UP THROUGH SAID INCLINED AND VERTICAL DUCT PORTIONS, SAID VERTICAL DUCT PORTION HAVING A GIVEN UNIFORM CROSS-SECTIONAL AREA SUCH THAT FOR A GIVEN RATE OF FLOW OF THE SORTING FLUID FED INTO SAID INCLINED DUCT PORTION, THE VELOCITY OF FLOW OF THE FLUID THROUGH SAID VERTICAL DUCT SECTION IS GREATER THAN THE SINKING VELOCITY OF THE FINE OR LOW DENSITY PARTICLES IN THE MATERIAL, BUT LESS THAN THE SINKING VELOCITY OF THE COARSE OR DENSE PARTICLES THEREOF SO THAT THE FINE OR LOW DENSITY PARTICLES ARE CARRIED BY SUCH FLUID FROM SAID INTERMEDIATE ZONE TO SAID DISCHARGE MEANS AND THE COARSE OR DENSE PARTICLES ARE UNABLE TO REACH SAID DISCHARGE MEANS AND TEND TO SINK INTO THE LOWER INCLINED DUCT PORTION, THE FLOOR OF SAID INCLINED DUCT PORTION HAVING A SLOPE STEEPER THAN THE NATURAL EQUILIBRIUM SLOPE THE COARSE OR DENSE PARTICLES WOULD ASSUME IN STATIC FLUID, BUT NOT OF SUCH STEEPNESS THAT THE FLUID CANNOT PENETRATE