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U.S. Department of Energy
Office of Scientific and Technical Information

Process for upgrading coal

Patent ·
OSTI ID:5603444
This patent describes a process for reducing the sulfur content and ash content of a feed coal containing sulfur and mineral matter. It comprises: treating the feed coal in a reaction zone with fused alkalimetal caustic at an elevated temperature to remove mineral matter and sulfur from the feed coal, yielding a caustic-treated coal containing chemically bound alkali; washing the caustic-treated coal with water to yield water-washing coal and a caustic-rich water; washing the water-washed coal with carbonic acid for releasing chemically bound alkali from the water-washed coal to yield carbonic acid-washed coal and an alkali metal carbonate solution; and washing the carbonic acid-washed coal with an acid stronger than the carbonic acid to yield product coal having a sulfur content lower than the sulfur content of the feed coal and an ash content lower than the ash content of the feed coal, and spent acid.
Assignee:
TRW Inc., Redondo Beach, CA (USA)
Patent Number(s):
US 5059307; A
Application Number:
PPN: US 7-419659
OSTI ID:
5603444
Country of Publication:
United States
Language:
English