Coal desulfurization and demineralization by chemical/physical treatments

Thesis/Dissertation · Sun Jan 01 00:00:00 EST 1984

OSTI ID:5004857

Fan, C W

A multistep process was developed and demonstrated for producing super clean coal. In this process, the coal is first leached with a dilute sodium carbonate solution under oxygen pressure at 150C to oxidize pyritic sulfur and some of the organic sulfur to produce water-soluble sulfur species. Next, the temperature of the alkaline suspension is raised above 250C but under non-oxidizing conditions to convert clays and other minerals to acid-soluble materials. The solids are subsequently separated by filtration and then extracted with a dilute mineral acid. Individual minerals including various clays, quartz, carbonates, and pyrite were reacted with hot alkaline solutions and the solid reaction products characterized by X-ray diffraction analysis. The solubility of the reaction products in dilute mineral acids was also investigated in detail. Kinetic data for the reactions of quartz and pyrite with alkaline solutions were collected and analyzed. A shrinking unreacted core model was used to analyze the pyrite data and determine the rate-controlling step. The basic preoxidation, alkaline leaching, and acid washing steps of the chemical leaching process were demonstrated with several types of coal to establish optimum treatment conditions. Various process variables including leaching temperature and time, alkali type and concentration, particle size, acid type and concentration, washing temperature and technique, and pulp density were investigated. Reductions in ash and sulfur contents and coal recovery were determined for different treatment conditions. The phase transformations of ash-forming mineral matter in coal during the leaching treatments were monitored and identified by X-ray diffraction analysis. The results with coal were compared to those obtained when individual minerals were leached.

• Research Organization: Iowa State Univ. of Science and Technology, Ames, IA (USA)
• OSTI ID: 5004857
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
COAL
CLEANING
MINERALS
REMOVAL
SULFUR COMPOUNDS
CARBONATE MINERALS
CHEMICAL REACTION KINETICS
CLAYS
COAL PREPARATION
DEASHING
DESULFURIZATION
FILTRATION
LEACHING
OPTIMIZATION
ORGANIC SULFUR COMPOUNDS
PARTICLE SIZE
PHASE TRANSFORMATIONS
PYRITE
QUARTZ
SODIUM CARBONATES
SOLVENT EXTRACTION
TEMPERATURE DEPENDENCE
TIME DEPENDENCE
X-RAY DIFFRACTION
ALKALI METAL COMPOUNDS
CARBON COMPOUNDS
CARBONACEOUS MATERIALS
CARBONATES
CHALCOGENIDES
CHEMICAL REACTIONS
COHERENT SCATTERING
DIFFRACTION
DISSOLUTION
ENERGY SOURCES
EXTRACTION
FOSSIL FUELS
FUELS
IRON COMPOUNDS
IRON SULFIDES
KINETICS
MATERIALS
ORGANIC COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
REACTION KINETICS
SCATTERING
SEPARATION PROCESSES
SILICON COMPOUNDS
SILICON OXIDES
SIZE
SODIUM COMPOUNDS
SULFIDE MINERALS
SULFIDES
TRANSITION ELEMENT COMPOUNDS
010300* - Coal
Lignite
& Peat- Preparation- (1987-)
010402 - Coal
Lignite
& Peat- Purification & Upgrading