The federal Bureau of Mines performed laboratory tests using direct current to dewater and densify fine-grained coal sludge in order to alleviate disposal problems and lead to recovery of high energy value often present in this waste. The laboratory tests described in the main body of the report were performed on thickened underflow (no flocculant added) from a northern Appalachian coal preparation plant. Solids in this slurry was very fine with 65 percent of the particles less than 0.1 Mm in diameter. A variety of application procedures tested is exemplified by a test in which a soupy slurry (55 percent dry-weight moisture content) was converted into a firm dense material with a 20-percent dry-weight moisture content. These results were achieved in 3 hours with current density of 3.7 Amp/ft2 and a power expenditure of 35 kwhr/yd3. The treated material has an average heating value of 10,400 btu/lb. Varying current density, electrode configuration, and placement depth makes application of the treatment flexible.