Dewatering fine coal slurries by gel extraction

Technical Report · Mon Jan 01 04:00:00 EST 1990

OSTI ID:6881765

Gehrke, S H; Lyu, Lii-Hurng

A new technology called gel extraction has been evaluated to determine its economic viability in dewatering the fine and ultrafine coal slurries generated upon separation of sulfur and ash from clean coal during the physical coal cleaning process. Water must be removed from such slurries prior to transportation and combustion but the dewatering costs are substantial, especially for the fine particles below 28 mesh (0.6 mm). Gel extraction is a potential breakthrough in slurry dewatering technology. The goal of this project was to acquire the qualitative and quantitative data needed to estimate the potential of gel extraction for dewatering coal slurries. The specific objectives were to determine the maximum extents of dewatering (minimum surface moisture in the coal product), the clarity of the water removed (minimum solids content), the speed of the dewatering cycles, the service lifetime of the gels, and the factors which influence all of these. With the results obtained, an economic analysis of Ohio coal cleaning plant dewatering technologies was carried out. The polymer gel at the heart of this project, poly (N-isopropylacrylamide) (PNIPA), can swell several times its shrunken weight at 32[degrees]C by absorbing water at 25[degrees]C. In gel extraction, a shrunken NIPA gel is contacted with a slurry at ambient temperature or cooler; the gel swells by absorbing water from the slurry. The gel is then removed from the dewatered slurry and warmed above its critical temperature of 33[degrees]C, which returns it to the shrunken state by releasing the absorbed water. The facts that the gel is reusable and the process is simple and driven by low-grade energy (warm temperatures), and not inherently limited by particle size, made the process an attractive possible alternative to centrifugation, screening, filtration, etc. for slurry dewatering.

• Research Organization: Ohio Coal Development Office, Columbus, OH (United States); Cincinnati Univ., OH (United States). Coll. of Engineering
• Sponsoring Organization: STOFOH; Ohio State Government, Columbus, OH (United States)
• OSTI ID: 6881765
• Report Number(s): OCDO-93006027; ON: TI93006027; CNN: CDO/R-87-57
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010300* -- Coal
Lignite
& Peat-- Preparation-- (1987-)
CARBONACEOUS MATERIALS
COAL
COAL FINES
COAL PREPARATION
COLLOIDS
DISPERSIONS
DOCUMENT TYPES
ENERGY SOURCES
EXTRACTION
FOSSIL FUELS
FUEL SLURRIES
FUELS
GELS
MATERIALS
MIXTURES
PERFORMANCE TESTING
POLYMERS
PROGRESS REPORT
REMOVAL
SEPARATION PROCESSES
SLURRIES
SUSPENSIONS
TESTING
WATER REMOVAL