Horizontally disposed serial elutriation apparatus

A method for separating particles of different density from a mixture of material having particles of different density, comprising:

• placing a portion of the mixture of material having particles of different density into a hopper of an elutriation apparatus having a mechanism adapted to move water along a path, the mechanism comprising a stationary outer cylindrical housing having a horizontal central axis and a length from a first end to a second end assembled concentrically with a stationary inner cylindrical housing of the same length having the same central axis, creating an annular space between the housings, with a spiral fin implemented in the annular space between the cylindrical housings, providing a spiral path from the first end to the second end, the hopper interfaced to an entry port through the outer cylindrical housing at a first end of the mechanism into the spiral path;
• adding water through an inlet through the hopper, creating a flow of water entraining particles of different density along the spiral path;
• interfacing a plurality of elutriation columns through the stationary outer cylindrical housing, along a line at a lowermost point of the outer cylindrical housing parallel with the central axis, each elutriation column having a vertical bore with water controlled to travel up the vertical bore at one velocity, and having also a capture element at the bottom of the bore;
• separating from the water entraining particles of different density, at each elutriation column, particles of a density sufficient for the particles to settle in the elutriation column at a velocity greater than the upward velocity of water in the bore of the elutriation column;
• and
• collecting the separated particles from the capture element at the bottom of each elutriation column.