Patent ID: 7497335

Claim:
A process for separating two or more types of feedstock particles, the feedstock including at least two types of particles each having a different specific gravity, the process comprising: dispersing the particles into a first fluid having a specific gravity between that of the lightest and the heaviest particles in the feedstock and creating a slurry; feeding the dispersed particle slurry into a first hydrogravity tank, such that most particles with a specific gravity less than that of the first fluid float, and most particles with a specific gravity greater than that of the first fluid sink; removing the floating particles from the first hydrogravity tank to form a first product stream and removing the sinking particles from the first hydrogravity tank to form a second product stream; directing at least one of the first and second product streams from the first hydrogravity tank to a second cycle of dispersing and feeding operations using a second fluid with substantially the same specific gravity as the first fluid used in the first hydrogravity tank, wherein the second cycle includes feeding the directed at least one product stream to a second hydrogravity tank, such that most particles with a specific gravity less than that of the second fluid float, and most particles in the directed at least one product stream with a specific gravity greater than that of the second fluid sink; and removing the floating and sinking particles from the second hydrogravity tank.