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Hydrothermal pretreatment of coal before molten caustic leaching

Conference ·
OSTI ID:10188989
A hydrothermal pretreatment of coal samples before caustic leaching results in efficient sulfur removal using reduced amounts of caustic and to recovery of a higher fraction of the energy content of the feed coal than caustic leaching without the pretreatment. Pretreating an Illinois No. 6 coal with boiling water followed by a float-sink separation using 50% aqueous NaOH as the heavy medium, and then leaching the floated coal with only the caustic adhering to the float portion (less than 1 part caustic to 1 part water to 1 part coal) at 390{degrees}C for 15 minutes led to the same residual levels of sulfur in the cleaned coal (0.5%) as was obtained performing the float-sink procedure and leaching procedures on a non-prewashed coal using 2.4 parts caustic to 1 part coal. When prewashed Illinois No. 6 coal was leached with lesser amounts of caustic, the energy recoveries in the cleaned coal were about 5--10% higher than when non-prewashed coal was leached with the larger amounts of caustic.
Research Organization:
Ames Lab., IA (United States)
Sponsoring Organization:
USDOE, Washington, DC (United States)
DOE Contract Number:
W-7405-ENG-82
OSTI ID:
10188989
Report Number(s):
IS-M--764; CONF-931014--2; ON: DE94000693
Country of Publication:
United States
Language:
English