Carbon dioxide for fine coal flotation: Final report, September 1985--December 1987. [With CO/sub 2/ pretreatment in a pressure filter]

Technical Report · Tue Dec 01 04:00:00 EST 1987

OSTI ID:6983844

Miller, J D

A detailed research effort on the fundamentals of coal flotation by carbon dioxide was initiated. Research has been carried out on different aspects of the problem including hydrophobic characterization, bench-scale flotation, carbon dioxide adsorption, electrokinetic behavior, and FTIR spectroscopy for coals of different rank. Coal hydrophobicity as defined by contact angle and bubble attachment time measurements also can be characterized by diffuse reflectance FTIR spectroscopic criterion---the hydrophilicity index---which contrasts the relative abundance of surface hydrophilic groups with the relative abundance of surface hydrophobic groups. This index can be used to predict or estimate the flotation behavior of coals of different rank. Rank-dependence of coal hydrophobicity established by macroscopic characterization and FTIR spectroscopy can be verified by XPS for dry coals and in-situ ATR-FTIR spectroscopy for wet coals. Contact-angle and bubble attachment-time measurements as well as FTIR spectroscopy reveal the enhanced hydrophobicity of CO/sub 2/-treated coal and explain the improved flotation response with carbon dioxide flotation. BET measurements, differential scanning calorimetry, and FTIR spectroscopy confirmed that CO/sub 2/ is specifically adsorbed at the coal surface. In-situ FTIR studies suggest that carbon dioxide adsorbed on both the internal and external surface of coal is polarized. Partial solvation of the first layer of adsorbed CO/sub 2/ results in a CO/sub 2/-covered coal surface, which appears to convert some of the hydrophilic sites into hydrophobic sites. The high specific affinity of coal for CO/sub 2/ results in the displacement of pore water and leads to nanobubble formation at the coal surface during flotation. Specific adsorption and the nanobubble formation contribute to the enhanced flotation response. 67 refs., 33 figs., 16 tabs.

• Research Organization: Utah Univ., Salt Lake City (USA). Dept. of Metallurgy and Metallurgical Engineering
• DOE Contract Number: FG22-85PC80530
• OSTI ID: 6983844
• Report Number(s): DOE/PC/80530-T7; ON: DE88005659
• 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
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
ADSORPTION
AFFINITY
AGING
ASH CONTENT
BENCH-SCALE EXPERIMENTS
BUBBLES
CALORIMETRY
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBONACEOUS MATERIALS
CHALCOGENIDES
CHEMICAL COMPOSITION
CHEMICAL PROPERTIES
COAL
COAL PREPARATION
COAL RANK
DOCUMENT TYPES
ELECTRON SPECTROSCOPY
ENERGY SOURCES
FLOTATION
FOSSIL FUELS
FUELS
MATERIALS
MEASURING METHODS
OXIDES
OXYGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
PROGRESS REPORT
SEPARATION PROCESSES
SOLVATION
SORPTION
SORPTIVE PROPERTIES
SPECIFICITY
SPECTROSCOPY
SURFACE PROPERTIES
SURFACES