SOIL WASHING CAN RECLAIM THIS unintended TRAGEDY
The separation of less dense particles (soil or mineral waste) from particles of higher density (gold, mercury, tin, sulfides) in a classified slurry is the goal of elutriation in this apparatus. Separation of PAY is accomplished by means of a slurry introduced into a slow upward stream of water, in a vertical column, so that the less dense particles are carried upward and out of the apparatus while dense particles fall past upwelling water to be collected in the apparatus. Most elutriation tanks and material handling tanks are overwhelmingly oriented in a vertical column thus INHERENTLY inefficient at handling a high throughput of process material.
The sedimentation aspect of separation in elutriation apparatus is gravity driven. In a vertical column, for example, water may be fed to travel upward in a laminar flow with a classified mixture of particles of solid or semi-solid matter entrained in the water. Denser particles will sink in the water column more rapidly than the upward velocity of the water in the column and will collect at the bottom of the column. Less dense particles will travel upward with the water flow and may be caused to spill over an upper barrier. The density of particles that will settle or rise can bevaried by varying the velocity of the upward flow of water in the column. There are several problems often experienced in vertically oriented up-flow elutriation apparatus. One is that the column holding process material typically is rather large in diameter where it is difficult to control the internal flow conditions to provide a truly laminar flow. Another is that with a single column only particles of a certain density will be separated out, and readjustment must be done to configure to retrieve particles of a different density. I determined that what is clearly needed is a horizontally oriented material delivery apparatus with a serial plurality of elutriation columns that may be controlled to separate and deliver clean particles of different density in each column, quickly and continuously.
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