Surface properties of coal and their role in fine coal processing

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1990

OSTI ID:6096626

Diao, Jianli

Emphasis has been given to the surface oxidation of coal and its role in wetting behavior and the flotation response of coal. A correlation was observed among the interfacial properties of as received Cambria {number sign}78 and New Zealand coals. At their isoelectric points (IEP), both coals exhibit a minimum in the induction time for bubble-particle contact and a maximum in their flotation rate constant, which indicates that the coal surface exhibits maximum hydrophobicity at its IEP. Increasing the salt (sodium nitrate) concentration results in a decrease in the zeta potential and the induction time and an increase in the flotation rate constant of the coals tested. The distribution can be determined by the film flotation technique using aqueous methanol solutions of various compostions to regulate the liquid surface tension. A method has been developed to estimate the contact angles of paticles and the distribution of hydrophobic and hydrophilic sites on coal particles from film flotation data. This new approach has been verified by comparing the calculated mean contact angles from film flotation results with the measured values on the flat surface for a number of pure materials and coal samples. Oxidation has a deleterious effect on the behavior of coal particles in fine coal processing. When coals are oxidized, the water retention capacity of the filter cake increases and the flotation recovery of the coals decreases. The results show that the hydrophilic oxygen functional groups produced on the coal surface during oxidation increase the interaction of water molecules with coal, thereby increasing the water retention capacity and decreasing flotation recovery.

• Research Organization: California Univ., Berkeley, CA (United States)
• OSTI ID: 6096626
• 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
ALKALI METAL COMPOUNDS
BUBBLES
CARBONACEOUS MATERIALS
CHEMICAL REACTIONS
COAL
COAL PREPARATION
COAL RANK
CORRELATIONS
ENERGY SOURCES
FLOTATION
FOSSIL FUELS
FUELS
HYDROXY COMPOUNDS
INTERFACES
MANAGEMENT
MATERIALS
MATERIALS RECOVERY
METHANOL
NITRATES
NITROGEN COMPOUNDS
ORGANIC COMPOUNDS
OXIDATION
OXYGEN COMPOUNDS
POTENTIALS
PROCESSING
RECOVERY
SEPARATION PROCESSES
SODIUM COMPOUNDS
SODIUM NITRATES
SURFACE POTENTIAL
SURFACE PROPERTIES
SURFACE TENSION
WASTE MANAGEMENT
WASTE PROCESSING
WETTABILITY