Philippine E-Journals

Chemical and Toxicity Characterization of Coal Ash from Coal Dust-Fired Gravity Circulation Boiler

Denvert Pangayao | Susan M. Gallardo | Michael Angelo B. Promentilla | Roy Alvin Malenab | Derrick Ethelbhert C. Yu | Jonathan Dungca

 

Abstract:

This research focus on the chemical and toxicity characterization of coal ash from coal dust fired gravity circulation boiler. The objective of the study is to determine the toxicity of the coal ash and its application as a geopolymer raw material. In this study, coal ash samples were collected from both the silo and ash pond. Results from X-ray diffraction analysis (XRD) of this ash indicate major ferro-, alumino-, and silicate minerals such as quartz-SiO2, lime-CaO, tricalcium aluminate, and magnetite. Moreover, X-ray Fluorescence analysis (XRF) confirms the presence of such major elements such as silicon, aluminum, calcium and iron. Results from XRD and XRF suggest the presence of amorphous silica and alumina which are important precursor to produce a geopolymer-based material. In addition, the fly ash can be classified as moderate calcium content-fly ash which may exhibit both pozzolanic and cementious properties. However, the sulfur content is relatively high to meet the requirement of class C or F fly ash according to ASTM specification. Leachability analysis of the coal ash sampled from ash pond was also performed based on Toxicity Characteristics Leaching Procedure (TCLP). TCLP results indicate that the leachate concentration of toxic metals such as arsenic, cadmium, chromium, lead, and mercury from the coal ash disposed in the ash pond were below the permissible limit set by environmental regulatory agency. Thus, the coal ash can be classified as non-hazardous based on this regulatory leaching test.