Abstract |
As is well-known much of the electric utility coal is not cleaned at all, but is received as raw (usually crushed or screened to minus 1-1/2 inches) run-of-mine. Some of it is partially cleaned to remove the larger pieces of rock. Electric generating stations placed at the mine site are usually fed raw or partially cleaned crushed coal. Complete preparation plants usually produce other sizes such as various sizes of stoker and nut or furnace coal, shipping the finer sizes or various composites to the electric utilities. As the markets for these various sizes diminish, the trend is towards one product -- utility coal, and with this is combined the unit or integral train concept for lower rail transportation costs. In each of the case studies actual plant costs are used, where possible. There is a wide divergence in both capital and operating costs. There are various reasons for this such as, differences in type of equipment used, location, capacity, sizes of coal produced, degree of cleaning, handling of fines, thermal drying, extent of automation and the age of the plant. (Author) |