Enhancement of the wettability of coal powders using surfactants

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:5001812

Mohal, B R

The wettability of coal powders has been studied with an objective to enhance the effectiveness of water sprays in dust suppression. The Walker sink time method for measuring wettability of coal particles was modified to obtain more reliable data. In addition, a new technique (Imbibition Time Measurements) was developed to determine the engulfment time of coal particles. Kinetic adsorption studies were carried out to determine the mechanism of adsorption of an ethoxylated nonylphenol on coals of different rank. In addition, selected contact angle measurements were made to explain wetting phenomena. From the wetting tests a minimum concentration of the surfactant necessary to wet the coals was determined and it was found to be independent of the coal rank but was dependant upon the number of ethoxy groups in the surfactant molecule. The higher rank coals were found to be more easily wetted than were the lower rank coals. The short time contact angel measurements suggest that spreading might control the engulfment of particles. From the imbibition time measurements of a large number of individual particles, the homogeneity/heterogeneity of particles with regard to their wetting behavior was determined. Short time adsorption studies indicate that the uptake of the surfactant involved both a rapid adsorption process at the external surface and a slow diffusion process. It is proposed that at low surfactant concentrations, the nonionic surfactant adsorbs through both hydrophobic and hydrophilic interactions with the molecule lying parallel to the surface. Under such conditions coal becomes more hydrophobic and wetting is not possible. At higher concentrations surface micelles form at the hydrophobic sites through hydrophobic chain interaction and wetting is spontaneous under such conditions.

• Research Organization: Pennsylvania State Univ., University Park, PA (USA)
• OSTI ID: 5001812
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010600* -- Coal
Lignite
& Peat-- Properties & Composition
010800 -- Coal
Lignite
& Peat-- Waste Management
ADSORPTION
CARBONACEOUS MATERIALS
COAL
COAL FINES
COAL RANK
CONTROL
DUSTS
ENERGY SOURCES
FOSSIL FUELS
FUELS
MATERIALS
MEASURING METHODS
OPTIMIZATION
SORPTION
SPRAYS
SURFACE PROPERTIES
SURFACTANTS
WETTABILITY