High-temperature corrosion resistance of alumina refractories to lignite ash slags

Technical Report · Mon Jan 01 04:00:00 EST 1979

OSTI ID:5345850

Pahlman, J E; Anderson, C F; Khalafalla, S E

As part of its goal to minimize the requirements for mineral commodities through conservation and substitution, the Bureau of Mines is conducting research to determine the resistance of alumina refractories to corrosion by alkali-containing slags that could result from burning of the abundant Western lignites in metallurgical operations. Static corrosion tests were performed at 1000 to 1350/sup 0/C and dynamic tests were performed at 1400 to 1600/sup 0/C to investigate the stability of refractory specimens in slag environments. In general, the degree of refractory attack increased with decreasing alumina content in the refractory and with increasing alkali content of the lignite ash. The parabolic kinetics observed in static tests suggested that a reaction product layer is formed through which ionic diffusion must occur to sustain the reaction with the refractory material. The linear kinetics observed in dynamic tests in high-viscosity slags indicated a shearing of the reaction product layer by viscous slags. The observed lesser attack of refractories by low-viscosity slags can be explained on this basis. Two 99-percent-alumina refractories and two 90-percent-alumina refractories formed an expanded protective layer with the more viscous slags but not with the less viscous slags. Corrosion of 90-percent-alumina refractories increased exponentially with temperature. In refractories with the same nominal alumina content, those that contain a combination of ..cap alpha..-Al/sub 2/O/sub 3/ and mullite (3Al/sub 2/O/sub 3/.2SiO/sub 2/) have better corrosion resistance than those containing a combination of ..cap alpha..-Al/sub 2/O/sub 3/, cristobalite (SiO/sub 2/ mineral), and mullite. In alkali environments (1300 to 1400/sup 0/C), 90- to 99-percent-alumina refractories are recommended for use as furnace linings.

• Research Organization: Bureau of Mines, Pittsburgh, PA (USA)
• OSTI ID: 5345850
• Report Number(s): BM-RI-8430
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360205* -- Ceramics
Cermets
& Refractories-- Corrosion & Erosion
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
BROWN COAL
CARBONACEOUS MATERIALS
CHALCOGENIDES
CHEMICAL REACTIONS
COAL
COMBUSTION
CORROSION RESISTANCE
CORROSIVE EFFECTS
ENERGY SOURCES
FOSSIL FUELS
FUELS
LIGNITE
METALLURGICAL EFFECTS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
SLAGS
STABILITY
THERMOCHEMICAL PROCESSES