Changes in Midwestern Fly Ash II. Air Classification, Magnetic Separation and the Pozzolanic Characteristics of the Ash

Anne Oberlink, University of Kentucky Center for Applied Energy Research
Sydney Dendekker, University of Kentucky Center for Applied Energy Research
Haley Johnson, University of Kentucky Center for Applied Energy Research
Thomas Robl, University of Kentucky Center for Applied Energy Research

Description

Changes in Midwestern Fly Ash II. Air Classification, Magnetic Separation and the Pozzolanic Characteristics of the Ash Authors Ms. Anne Oberlink - United States - University of Kentucky Center for Applied Energy Research Ms. Sydney Dendekker - United States - University of Kentucky Center for Applied Energy Research Ms. Haley Johnson - United States - University of Kentucky Center for Applied Energy Research Dr. Thomas Robl - United States - University of Kentucky Center for Applied Energy Research Dr. Bob Jewell - United States - University of Kentucky Center for Applied Energy Research Abstract Six current production fly ashes from Kentucky power plants were processed into coarse and fine-size fractions with an air classifier. This process separates material by size and density. The strong contrast with the silicate fraction of the fly ash in density to that of the magnetite (~5.2 to ~2.4 g/cm3) makes this separation less challenging than that of carbon. The classification of these fly ashes resulted in finer-sized ash yields ranging from +90% to ~50%. As expected, the coarse ash had high concentrations of magnetite (up to ~55% by weight). The fine fraction had increased SiO2 and Al2O3 content and reduced Fe2O3. This is reflective of greater fused glass content. The fine fraction was also substantially improved in fineness as defined by retention on a 325-mesh screen. It did have an increased LOI over the parent material. However, with one exception, this increase was within the requirement of ASTM C-618 of 5%. Preliminary results found that the fine fraction of the fly ash had improved the pozzolanic activity, as measured by the EN-196 strength index test and resistivity measurements over the parent ash. The coarse fraction of the ash did not pass the strength index test and showed little improvement in resistivity. The beneficiation potential for these fly ashes and new uses for coarse and fine materials will be discussed.

 
May 14th, 1:00 PM May 14th, 1:30 PM

Changes in Midwestern Fly Ash II. Air Classification, Magnetic Separation and the Pozzolanic Characteristics of the Ash

Grand Rapids, Michigan

Changes in Midwestern Fly Ash II. Air Classification, Magnetic Separation and the Pozzolanic Characteristics of the Ash Authors Ms. Anne Oberlink - United States - University of Kentucky Center for Applied Energy Research Ms. Sydney Dendekker - United States - University of Kentucky Center for Applied Energy Research Ms. Haley Johnson - United States - University of Kentucky Center for Applied Energy Research Dr. Thomas Robl - United States - University of Kentucky Center for Applied Energy Research Dr. Bob Jewell - United States - University of Kentucky Center for Applied Energy Research Abstract Six current production fly ashes from Kentucky power plants were processed into coarse and fine-size fractions with an air classifier. This process separates material by size and density. The strong contrast with the silicate fraction of the fly ash in density to that of the magnetite (~5.2 to ~2.4 g/cm3) makes this separation less challenging than that of carbon. The classification of these fly ashes resulted in finer-sized ash yields ranging from +90% to ~50%. As expected, the coarse ash had high concentrations of magnetite (up to ~55% by weight). The fine fraction had increased SiO2 and Al2O3 content and reduced Fe2O3. This is reflective of greater fused glass content. The fine fraction was also substantially improved in fineness as defined by retention on a 325-mesh screen. It did have an increased LOI over the parent material. However, with one exception, this increase was within the requirement of ASTM C-618 of 5%. Preliminary results found that the fine fraction of the fly ash had improved the pozzolanic activity, as measured by the EN-196 strength index test and resistivity measurements over the parent ash. The coarse fraction of the ash did not pass the strength index test and showed little improvement in resistivity. The beneficiation potential for these fly ashes and new uses for coarse and fine materials will be discussed.