Separation of particulate solids of varying densities in a fluidized bed

Claim 1

A process for the separation of a particulate feedstock into a light fraction and a heavy fraction consisting essentially of a. feeding said feed stock into a fluidized bed of particulate material whose particle size and specific gravity, relative to the particle sizes and specific gravities of said light and heavy fractions, are such that one of said fractions readily stratifies as a top or bottom layer adjacent said bed, and the other of said fractions readily intermixes with said bed material as a non-stratified fraction throughout said bed; b. removing said stratified layer away from said bed; c. removing said other fraction from within said bed while said other fraction is non-stratified and intermixed with said bed material; and wherein the relationship of the particle size (d1) and specific gravity ( delta 1) of said other fraction to the particle size (d2) and specific gravity ( delta 2) of said bed material is such that the particle size of said other fraction is less than fouR times the theoretical size of said other fraction as calculated from the formula d1 d2( delta 2/ delta 1)3/2, and wherein the relationship of the particle size (d3) and specific gravity ( delta 3) of said one fraction of the particle size (d2) and specific gravity ( delta 2) of said bed material is such that the particle size of said one fraction is at least 10 times the theoretical size of said one fraction as calculated from the formula d3 d2( delta 2/ delta 3)3/2.