Chemistry of ash agglomeration in the U-GAS process

Conference · Mon Jan 01 04:00:00 EST 1979

OSTI ID:5694500

Mason, D. M.; Patel, J. G.

Agglomerated ash in the form of rounded beads was produced in HYGAS pilot plant tests on coke and washed Kentucky coal. With both feeds, formation of the agglomerates is dependent on production of an iron-rich, relatively low-melting matrix in which a substantial portion of other ash is embedded. The matrix, which appears to have been molten in the gasifier, consists predominantly of a ferrous aluminosilicate mixture with smaller amounts of other oxides. The aluminosilicate matrix is produced by reaction of iron oxides with aluminosilicate (clay minerals) in the coal. Most of the iron in the Kentucky coal occurs as pyrite, FeS/sub 2/, with small amounts present in other forms, perhaps as carbonate or as a constitutent of the clay minerals. Pyrite readily loses half its sulfur to form ferrous sulfide, FeS, when heated to reactor bed temperature. Thermodynamic data indicate that ferrous sulfide cannot be oxidized to an oxide in the product gas atmosphere of the gasifier. Conditions may be more favorable in the bed below the coal entry level, but it appears likely that most of the oxidation of sulfide occurs in the vicinity of the oxygen reaction region. Oxidation of ferrous sulfide and formation of the agglomerating matrix material were achieved in runs on washed Kentucky coal but not in some runs on run-of-mine coal. From phase diagrams and other evidence raction of the iron with only part of the aluminosilicates in the ash is an essential feature for production of the low-melting material.

• OSTI ID: 5694500
• Report Number(s): CONF-790917-15
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010404* -- Coal
Lignite
& Peat-- Gasification
AGGLOMERATION
ASHES
CHALCOGENIDES
CHEMISTRY
COAL GASIFICATION
DIAGRAMS
FLOWSHEETS
FUNCTIONAL MODELS
GASIFICATION
GEOLOGY
IRON COMPOUNDS
IRON OXIDES
IRON SULFIDES
MELTING
MINERALS
ORES
OXIDES
OXYGEN COMPOUNDS
PETROLOGY
PHASE STUDIES
PHASE TRANSFORMATIONS
PILOT PLANTS
PYRITE
PYRITES
RESIDUES
SULFIDES
SULFUR COMPOUNDS
SULFUR ORES
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPOUNDS
U-GAS PROCESS