• Coal drying. Coal preparation plants that employ fine coal cleaning by froth flotation can produce an unacceptable amount of moisture in the product. Thermal drying, in which the wet coal is dried in the hot gas generated by a coal-or gas-fired burner, is used in some plants to reduce the moisture content.

  • Refuse and tailings management. Waste management is an integral part of coal preparation. Coarse refuse is transported to the solids disposal area, where it can form a tailings impoundment or be placed in a suitable landfill. Tailings (fine solid waste in water) are usually transported by pipeline to an impoundment area where the tailings settle out; the clarified water is reused in the plant.

Coal Preparation Plants

Each year, Coal Age magazine conducts a census of coal preparation plants in the United States (Fiscor, 2005). The overall findings of the survey (summarized in Table E.1) are generally accepted within the industry as a reasonably accurate reflection of the condition of the coal preparation industry. According to the Coal Age article, “plants reported an average recovery rate of 57%.” Given the total raw coal capacity of the surveyed plants (158,187 tons per hour), this corresponds to a clean-coal capacity of 790 million tons per year, assuming 24/7 operation.

The number of preparation plants increased by 53 since the 2000 survey, and at least 10 new plants were built and 25 were significantly upgraded in the

TABLE E.1 Characteristics of Coal Preparation Plants in the United States in 2004, by State

State

Number of Plants

Raw Coal Capacity (ton/hr)

Average Age

West Virginia

66

48,382

24

Kentucky

73

43,320

21

Pennsylvania (bituminous)

20

14,575

30

Virginia

25

10,700

21

Illinois

11

10,450

21

Indiana

19

8,950

17

Alabama

6

8,120

26

Ohio

15

5,360

24

Pennsylvania (anthracite)

15

1,980

35

Maryland

1

1,800

N/A

Colorado

4

1,750

7

Washington

1

1,750

NA

Utah

6

600

NA

Tennessee

2

450

NA

Total

264

158,187

23

SOURCE: Fiscor (2005).



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