The petrochemistry of coal ash slags. Part 3. Behavior of the rosebud slag-limestone system

Rosebud subbituminous coal has been used as a feedstock in many coal conversion pilot plants, including the BI-GAS and Grand Forks Energy Technology Center slagging gasifiers. Limestone has been investigated as a fluxing agent for Rosebud slag. Slag viscosity decreases as an increasing function of l...

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Bibliographic Details
Published in:Fuel processing technology 1981, Vol.5 (1), p.157-164
Main Authors: Schobert, Harold H, Witthoeft, Carol
Format: Article
Language:English
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Summary:Rosebud subbituminous coal has been used as a feedstock in many coal conversion pilot plants, including the BI-GAS and Grand Forks Energy Technology Center slagging gasifiers. Limestone has been investigated as a fluxing agent for Rosebud slag. Slag viscosity decreases as an increasing function of limestone addition to about 30% limestone, but further addition causes the viscosity to increase. Traditional approaches to describing slag viscosity, such as the base/acid ratio, fail to account adequately for this effect. A petrographic normative calculation predicting structures present in Rosebud slag-limestone melts shows that initial additions of limestone break down complex framework silicates in favor of orthosilicate structures. The calculation also predicts that calcium, aluminium, and silicon oxides are the most important in determining melt properties. The limestone fluxing action can be interpreted using the CaOAl 2O 3SiO 2 ternary phase diagram. Studies of Rosebud slag-limestone melts using a heated stage microscope and X-ray diffraction provide empirical validation for the use of this ternary system in explaining the melt behavior.
ISSN:0378-3820
1873-7188
DOI:10.1016/0378-3820(81)90028-X