five years to 2005 (Fiscor, 2005). The survey notes that “while they employ new equipment, technology, and circuitry, U.S. prep plants have in general remained essentially the same. The typical U.S. prep plant employs heavy media separation and was built in 1983. It has a raw capacity between 500 and 1,000 tons per hour. Although more plants are employing large diameter cyclones, the plants still rely mainly on heavy-media vessels for primary separation and heavy media cyclones for intermediate separation. For fine coal recovery, the plants prefer spirals. Centrifugal dryers are popular. On the technology side, the industry has not embraced online analysis on a widespread basis, but it has adopted the use of PLCs extensively” (Fiscor, 2005).1


A PLC is a Programmable Logic Controller.

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