Aggregation and colloidal stability of fine-particle coal suspensions
The aggregation and colloidal stability of colloidal coal suspensions in the presence of varying concentrations of hydrogen ions, neutral salts, and aluminum sulfate were investigated. Critical concentration and critical pH values for coagulation and stabilization were determined from turbidity changes during settling following aggregation. Two colloidal suspensions of a bituminous coal representing stability extremes due to oxidation were compared. In the absence of other coagulants, vigorous oxidation lowered the isoelectric point of the coal sol from pH 5.1 to pH 1.1 and the pH for stabilization from 7.5 to 2.6. The coagulation of the suspensions followed the Schulze-Hardy rule as hydrophobic sols although the oxidized coal sol was slightly less sensitive to neutral salts. The entire log aluminum sulfate concentration-pH stability limit diagram for the oxidized coal sol was established. The boundaries of settling of the coal in the presence of aluminum sulfate were similar to other hydrophobic sols except for small differences in alkaline solution. Regions of ionic coagulation, rapid coagulation due to enmeshment in aluminum hydroxide precipitate, and restabilization were also observed and delineated.
- Research Organization:
- Ohio State Univ., Columbus
- OSTI ID:
- 6844284
- Journal Information:
- Environ. Sci. Technol.; (United States), Vol. 18:4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BITUMINOUS COAL
OXIDATION
SUSPENSIONS
AGGLOMERATION
FLOCCULATION
STABILITY
ALUMINIUM SULFATES
COLLOIDS
HYDROGEN IONS
PH VALUE
SALTS
ALUMINIUM COMPOUNDS
BLACK COAL
CARBONACEOUS MATERIALS
CHARGED PARTICLES
CHEMICAL REACTIONS
COAL
DISPERSIONS
ENERGY SOURCES
FOSSIL FUELS
FUELS
IONS
MATERIALS
OXYGEN COMPOUNDS
PRECIPITATION
SEPARATION PROCESSES
SULFATES
SULFUR COMPOUNDS
010600* - Coal
Lignite
& Peat- Properties & Composition