New technology could aid waste coal recovery

9 February 2009 – University researchers have developed and successfully tested a process that removes water from fine coal slurries, potentially making almost 3 billion tons of waste coal available for use.

During recent prototype tests at Arch Coal Co.’s Cardinal plant in Logan County, W.Va., the technology reduced moisture enabling the waste coal to be marketed commercially.

With funding from the National Energy Technology Laboratory, researchers at Virginia Tech say their hyperbaric centrifuge can efficiently dewater coal as fine as talcum powder. The centrifuge uses a combination of air pressure and centrifugal force to reduce moisture levels in fine coal, according to a Department of Energy press release. Tests show the centrifuge can dewater waste coal slurry to as much as 19 percent moisture with coal recovery greater than 97 percent.

The prototype unit used at the Cardinal plant can process around 30 gallons of feed slurry each minute. Decanter Machine Co. built the prototype and is building a full-scale commercial unit with a capacity of 600 gallons per minute.

The high moisture content of fine coal waste forces coal producers to discard the waste in storage areas called waste impoundments, according to the release.

Nationwide, some 2 billion tons of fine coal are stored in abandoned ponds. An additional 500 million to 800 million tons are in active ponds.