Surface and bulk characterization of particulates in fine-coal processing

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6034166

Narayanan, K S

An attempt is made to delineate the effects of composition, chemistry and oxidation of heterogeneous coal particulates, of different ranks and origins, on their wettability and floatability. The wetting characteristics of particulate coal samples are assessed using a relatively new film flotation technique, since it characterizes the distribution of lyophobic/lyophilic sites of an assembly of coal particles as encountered in a practical processing environment. The film flotation tests yield a wetting tension distribution diagram and an average critical wetting tension ({gamma}c), which can be used as a measure of hydrophobicity. The technique has been validated by determining the {gamma}c value (26-28 mN/m) for a homogeneous paraffin wax surface using wax-coated coal and other mineral particulates. The {gamma}c values for some of the high-ash and oxidized coals samples are estimated by combining the distribution curves of a number of as received and oxidized coal samples into a single curve by a normalization procedure, since they did not yield a complete distribution curve due to their hydrophilic nature. The film flotation results are compared with micro-scale flotation results obtained with Hallimond tube and vacuum flotation test methods. The Hallimond tube experiments using methanol solutions exhibit a frothing effect at low alcohol concentration and an entrainment effect at high concentrations. Vacuum flotation experiments using salt solutions correlate well with the film flotation results. The floatability of coals decreases with increasing {gamma}c values indicating the ability of film flotation to relate to coal floatability. In conclusion, film flotation appears to be a sensitive technique to delineate the surface wettability and floatability of heterogeneous coal particulates.

• Research Organization: California Univ., Berkeley, CA (USA)
• OSTI ID: 6034166
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010300 -- Coal
Lignite
& Peat-- Preparation-- (1987-)
010600* -- Coal
Lignite
& Peat-- Properties & Composition
ALCOHOLS
ASH CONTENT
CARBONACEOUS MATERIALS
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
COAL
COAL FINES
COAL PREPARATION
COAL RANK
CORRELATIONS
ENERGY SOURCES
FILMS
FLOTATION
FOSSIL FUELS
FUELS
HYDROXY COMPOUNDS
MATERIALS
METHANOL
ORGANIC COMPOUNDS
ORIGIN
OXIDATION
SALTS
SEPARATION PROCESSES
SURFACE PROPERTIES
SURFACE TENSION
VACUUM SYSTEMS
WETTABILITY