VALORIZATION OF CFB-COMBUSTION FLY ASHES AS THE RAW MATERIALS IN THE DEVELOPMENT OF VALUE-ADDED CERAMICS

摘要

The amounts of ashes from circulating fluidized bed (CFB)-combustion steadily increase with the increasing rate of implementation of this environmentally-friendlier technology for firing solid fuels in power generation units. Therefore, beneficial uses of these powdery by-products, which possess particular characteristics, should be identified instead of landfill them at significant environmental and economic impact. Their valorization in the manufacturing of value-added ceramics is a challenging research area. In the present study, CFB-coal combustion fly ashes, mainly bearing Si-Al phases, were utilized as 100% raw materials for the synthesis of ceramics by powder metallurgy (PM) techniques. Test specimens were fabricated by powder cold pressing followed by sintering at 900, 1000 or 1100 ℃. The produced materials were characterized by means of XRD and SEM-EDAX. Shrinkage upon sintering, apparent density, water absorption capability and Vick-ers microhardness were determined. The experimental results show that the recycling of CFB-fly ashes towards PM ceramics development is feasible. In fact, integral lightweight materials are obtained, exhibiting successfully-densified ceramic microstructures where quartz phases prevail. The physico-mechanical properties are proved to be influenced by the starting ash composition and the sintering temperature. The so-produced ceramics possess the potential to be tailored appropriately to meet requirements for specific applications of possible commercial interest.