Blackwater is a form of pollution produced in coal preparation. In its purification, coal is crushed in a coal preparation plant and then separated and transported as a coal slurry, From the slurry, incombustible materials are removed and the coal can be sized. After the recovery of the coal particles from this slurry, the remaining water is black, contains very fine particles of coal. This blackwater cannot be processed in a water treatment plant.
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Disasters
Impoundments for storage of blackwater and other coal-related wastes have a troubled history with often severe environmental consequences.
In February 1972, three dams holding a mixture of coal slurry in Logan County, West Virginia failed in succession: 130,000,000 US gallons (490,000 m3) of toxic water were released in the Buffalo Creek Flood. As discussed in the book The Buffalo Creek Flood: An Act of Man, out of a population of 5,000 people, 125 people were killed, 1,121 were injured, and over 4,000 were left homeless. The flood caused 50 million dollars in damages. Despite evidence of negligence, the Pittston Coal Company, which owned the compromised dam, called the event an "Act of God." In 2002, a 900-foot (270 m) high, 2,000-foot (610 m) long valley fill in Lyburn, West Virginia failed and slid into a sediment pond at the toe of the fill, generating a large wave of water and sediment that destroyed several cars and houses.
Other slurry disasters
Future technologies
The ultimate solution to the blackwater problem is to process coal without the use of water. Such dry-separation technologies are under development.