Fly ash quality and utilization

Conference · Fri Dec 01 04:00:00 EST 1995

OSTI ID:374590

Barta, L E; Lachner, L; Wenzel, G B ^[1]; Beer, M J ^[2]

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1. Inst. for Energy, Budapest (Hungary)
2. Massachusetts Inst. of Technology, Cambridge, MA (United States)

The quality of fly ash is of considerable importance to fly ash utilizers. The fly ash puzzolanic activity is one of the most important properties that determines the role of fly ash as a binding agent in the cementing process. The puzzolanic activity, however is a function of fly ash particle size and chemical composition. These parameters are closely related to the process of fly ash formation in pulverized coal fired furnaces. In turn, it is essential to understand the transformation of mineral matter during coal combustion. Due to the particle-to-particle variation of coal properties and the random coalescence of mineral particles, the properties of fly ash particles e.g. size, SiO{sub 2} content, viscosity can change considerably from particle to particle. These variations can be described by the use of the probability theory. Since the mean values of these randomly changing parameters are not sufficient to describe the behavior of individual fly ash particles during the formation of concrete, therefore it is necessary to investigate the distribution of these variables. Examples of these variations were examined by the Computer Controlled Scanning Electron Microscopy (CCSEM) for particle size and chemical composition for Texas lignite and Eagel Butte mineral matter and fly ash. The effect of combustion on the variations of these properties for both the fly ash and mineral matter were studied by using a laminar flow reactor. It is shown in our paper, that there are significant variations (about 40-50% around the mean values) of the above-listed properties for both coal samples. By comparing the particle size and chemical composition distributions of the mineral matter and fly ash, it was possible to conclude that for the Texas lignite mineral matter, the combustion did not effect significantly the distribution of these properties, however, for the Eagel Butte coal the combustion had a major impact on these mineral matter parameters.

• Research Organization: North Dakota Univ., Grand Forks, ND (United States)
• OSTI ID: 374590
• Report Number(s): DOE/MC/30097--5161-Pt.2; CONF-9410458--Pt.2; ON: DE96011553
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
CEMENTING
CHEMICAL COMPOSITION
COALESCENCE
COMBUSTION
COMBUSTION PRODUCTS
FLY ASH
LIGNITE
METALS
MINERALS
PH VALUE
SCANNING ELECTRON MICROSCOPY
TOXICITY
VISCOSITY
WASTE MANAGEMENT
WASTE PRODUCT UTILIZATION