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tank and the "purified" liquid can be recovered from the top for further processing. Another process is to concentrate the solids content by boiling off the unneeded liquid, thus leaving the solids behind as a relatively concentrated residue.

Because these processes could take several days (or even weeks or months) to occur, incur precious time and the expense of energy (for heating in the boiling method), they are considered economically unfeasible. This better alternative is a centrifuge.

Basically a centrifuge serves as a "miniature high-gravity settling tank".

The liquid-solid suspension is pumped through a closed environment and directly into a "bowl" that spins at incredible speeds. When the suspension strikes the bowl, it flies to the outer part of the bowl located furthest from the center of rotation and the liquid is subjected to multiple g-forces as many as 2,000 g's or even more. Because these forces are so extreme, the difference in weight (specific gravity, if you must be technical) of the suspended solids stands out like a sore thumb and these solids literally get thrown towards the outer portion of the centrifuge bowl within a few seconds.

After successful separation, the solids accumulate on the walls of the centrifuge bowl and are periodically discharged from the side of the machine through a series of small holes that open and shut within fractions of a second. This discharge is captured in a trough and exits from its own discharge port in the machine. The successfully purified fluids exit from the machine through separate pipes.

Physical separation that would otherwise take weeks has now been completed within several seconds.

Liquid-Liquid Separation

This same application of a high-g environment can also be used to split up two immiscible liquids which would otherwise take a very long time to separate. An example of this would be the separation of (un-usable) glycerol from the (useful) oily methyl esters in biodiesel production.

Liquid-Solids Separation To Concentrate Weapons-Grade Uranium

Iran seems to be using a kind of liquid-liquid centrifuge called a concentrator, and such machinery could provide a hypothetical environment such as the one depicted below.

After pumping uranium-laden water (perhaps originating as waste water from a nuclear power plant) into a centrifuge, the resultant layers of separation do not yield visible any solids accumulation. Rather there is a separation of relatively "light" and "heavy" water (thus, the term "heavy water"

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