Investigation of Coal Combustion Residuals for Ceramic Applications and Production
Open Access
- Author:
- Chop, Hannah
- Graduate Program:
- Energy and Mineral Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- February 20, 2024
- Committee Members:
- Barbara J Arnold, Thesis Advisor/Co-Advisor
Sarma V Pisupati, Committee Member
Jeremy Gernand, Program Head/Chair
Mohammad Rezaee, Committee Member - Keywords:
- Coal
fly ash
bottom ash
ceramics
coal waste
waste management
coal reject
sustainability - Abstract:
- The recycling and utilization of coal wastes to create ceramic materials provides added value for the coal industry while reducing environmental impacts associated with conventional materials and mitigating health and environmental risks posed by large-scale waste storage in impoundments. To understand the effects of various coal wastes on ceramic production, ashes from pulverized coal combustion, ashes from fluidized bed combustion, and coal reject were combined with bluestone clay tailings and bentonite then sintered at 998 ˚C, 1152 ˚C, and 1186 ˚C. The resulting ceramic samples were analyzed based on their shrinkage, weight loss, porosity, water absorption, and mineralogical composition. The optimal temperature for reaching the end of sintering maturity before pore formation and bloating began was determined to be 1152 ˚C. At this optimal temperature, water absorption, apparent porosity, and specific gravity reach a minimum. Samples sintered at 1152 ˚C and 1186 ˚C met ISO standards for groups BIa, BIb, and BII of construction tiles, with most samples possessing a water absorption of less than 3%. The lowest water absorption, 0.24%, and highest shrinkage, 17.8%, occurred in 50 wt.% fluidized bed fly ash sintered at 1152 ˚C. Samples made from fluidized bed combustion ash exhibit good water absorption and porosity, though the presence of calcium oxide may decrease strength over time. Samples containing 35 wt.% pulverized coal fly ash sintered at 1186 ˚C achieved 27.7 wt.% mullite and 15.6 wt.% cristobalite, indicating high strength. Pulverized coal bottom ash exhibited improved workability, low shrinkage rates (3-10%), and group BIb water absorption (<3%). Samples containing reject yielded moderate performance. Coal wastes used as raw materials for ceramics require little pretreatment and can be manufactured at lower temperatures than commercial ceramics. These benefits, in addition to environmental and economic advantages, indicate the feasibility of commercial coal waste ceramics. These results expand the understanding of coal waste behavior in ceramic materials and contribute to the nexus of sustainable development, waste management, and industry.