Feasibility of an Underground Hydraulic Coal Mine Near Wilkeson, Washington

摘要

This report presents a technical and economic study of the feasibility of establishing an underground hydraulic coal mine in the Wilkeson, WA, quadrangle, 25 miles southeast of Tacoma. The deposit contains reserves of more than 200 million tons of metallurgical coal. It is found in nine seams of minable thickness in a complex set of anticlines, synclines, and faults. Typical dip angles are up to 60 degrees, with minable seam thickness of 6 to 17 ft. A mine plan was made for a 200-million-ton-per-year clean mine using two shafts to access the deposit at a depth of 2,500 ft. The mining method uses water jets to break coal by sub-level retreat mining, fluming to a sump, and pumping the minus 0.25-in coal to a preparation plant on the surface. The plus 0.25-in coal is hoisted by skip. Cleaned coal is shipped by rail for export. A middlings product would be sold as thermal coal.