Patent ID: 8318507

Claim:
A method for the separation of particles with different densities by applying a force to a sample of particles suspended in a liquid volume of an extracting medium of specific density in a solid receptacle designed to separate said particles for such a purpose such that said particles having a density less than or equal to that of said extracting medium will not sediment and said particles having a density greater than said extracting medium will move through said liquid volume of the extracting medium in said receptacle, said method comprising the steps of: (a) delivering said sample to said receptacle as a suspension in said liquid volume of an extracting medium of known density; (b) applying said force to said sample to initiate the separation of said particles with different densities; (c) allowing said particles having a density greater than said extracting medium of known density to separate from the extracting medium to form a deposit on the inside vertical wall of said receptacle, such that the particles of density less than or equal to the known density of the extracting medium remain in suspension; (d) recovering all of the extracting medium from said receptacle to obtain said particles having a density less than or equal to that of said extracting medium of known density; (e) delivering to said receptacle a liquid volume of an extracting medium of a known density, which density is higher than that used in the immediately preceding extraction step; (f) resuspending the deposited particles in said receptacle from step (c) by agitation in the extracting medium of step (e); and (g) repeating steps (b)-(f) above cyclically until said deposit of particles from step (c) is not observable or a known density of an extracting medium is reached.