Regeneration of alkali in caustic desulfurization systems

Technical Report · Thu Sep 01 04:00:00 EDT 1988

DOI:https://doi.org/10.2172/6919316· OSTI ID:6919316

Markuszewski, R; Norton, G A; Chriswell, C D

The overall objectives of this project is to develop and test feasible reaction pathways for regenerating the spent caustic and acid streams used to remove sulfur and ash from coal in the molten caustic leaching (MCL) process being developed by TRW in California. This quarter, experiments on precipitating double salts using model spent acid solutions indicated that 90% or more of the solids present in the solution could be precipitated at 80{degree}C as natrojarosite and gypsum. The precipitate yield and the removal of iron and sulfate increased dramatically as the pH was increased from 1.1 to about 1.5. Maximum sodium removals of only about 70% were obtained. A spent acid stream obtained from the laboratory simulation of counter-current washing of caustic-treated coal, performed at Ames, was also tested for precipitate formation at 80{degree}C for 6 hours at a pH of 1.5. Initial visual observations indicated that the spent acid behaved similarly to the model solutions. Additional tests on precipitating another double salt, sideronatrite, from model solutions indicated that the precipitation of sideronatrite is probably not a viable option for treating spent acid streams from the MCL Process. Results of other experiments on model solutions containing NaOH, KOH, and carbonate and having compositions similar to those of actual spent caustic streams indicated that liming did not effectively precipitate carbonate. 4 refs., 3 figs.

• Research Organization: Ames Lab., IA (USA)
• Sponsoring Organization: DOE/FE
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6919316
• Report Number(s): IS-4970; ON: DE90017298
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010402* -- Coal
Lignite
& Peat-- Purification & Upgrading
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
ALKALI METALS
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CALCIUM SULFATES
DOCUMENT TYPES
ECONOMICS
ELEMENTS
GRAVIMELT PROCESS
GYPSUM
MANAGEMENT
MATERIALS RECOVERY
METALS
MINERALS
OXYGEN COMPOUNDS
PH VALUE
PRECIPITATION
PROCESSING
PROGRESS REPORT
RECOVERY
REMOVAL
SEPARATION PROCESSES
SODIUM
SULFATE MINERALS
SULFATES
SULFUR COMPOUNDS
WASTE MANAGEMENT
WASTE PROCESSING