Separation Process and Microstructure-Chemical Composition Relationship of Cenospheres from Lignite Fly Ash Produced from Coal-Fired Power Plant in Thailand

Abstract

The cenosphere is one becoming a focus of the power plant in terms of value addition and ash management. This study presents a systematic investigation and characterization of physical properties, morphological structures, and chemical composition of cenospheres separated from fly ash produced from the Mae Moh coal-fired power plant, Thailand. To our knowledge, this is the first report on cenospheres separation from Mae Moh class C fly ash, with high calcium content ~24 wt.%, by adopting the traditional wet separation method (using water as the medium) to separate the lightweight cenospheres. Various effects of process parameters (fly ash-to-water ratio, stirring method, ultrasonication, and size classification) were designed to examine the cenosphere recovery yield in comparison. The result has revealed the limit of physical stirring-settling effect associated with the cenospheres content by nature governing the percent recovery. The bulk cenospheres were subject to size sieving into different sized fractions, with the structure-chemical composition relationship established for more insight. The particle diameter/shell thickness ratio revealed its significant correlation with the aluminosilicate glass composition, with the relating cenosphere shell structures (single-ring and porous) mapped to compare for a better elucidation of their structure-property relationship. The phase composition was also studied.

Emerging trends in the recovery of ferrospheres and plerospheres from coal fly ash waste and their emerging applications in environmental cleanup

“…However, normally, PS should be larger due to the presence of filled gases and minerals. The size of PS varies from 0.2 to 8 µ, while the size of CS is 10-1,000 µ based on the TPPs, combustion temperature, and types of coal used (Yoriya et al, 2019;Yoriya and Tepsri, 2020). Ruptured PS release numerous smaller microspheres and mineral particles (Strzałkowska, 2021), as shown in Figures 3A, B, 4A, B, 5A, B where scanning electron microscope (SEM) images show ruptured PS with numerous small spherical particles present within them.…”

“…XRD of CS from lignite CFA of a Thailand TPP depicting their major minerals. Adapted from Yoriya and Tepsri (2020) and (Yoriya and Tepsri, 2021).…”

“…PS with larger diameters (e.g., 100 µ) are very common in CFA, enclosing sub-microspheres or mineral fragments (mostly <10 µ) and reportedly have high mechanical strength and chemical reactivity (Snellings et al, 2021). PS have generally spherical-shaped particles with several smaller particles and mineral fragments (Yoriya and Tepsri, 2020). Both thick-and thin-walled PS release secondary plerospheres or mineral particles after wall rupture.…”

“…The carbon composition could be higher or lower based on the type of coal used for the fuel in the TPPS, and other operating conditions of the furnaces of the TPPs. Yoriya and Tepsri (2020) reported that the chemical composition of CS depended on the size of the particles, even though their basic elements remained the same. The CS size and chemical composition were assessed in CS collected from lignite CFA from Thailand TPPs.…”

COVID-19 Immunopathology, Particle Pollution, and Iron Balance

“…Coal fly ash with its many fine and ultrafine particles, and notably with hollow cavities [80,81] (Fig. 1), has been suggested as a possible carrier of respiratory viruses [82].…”