Plenary Lecture
Improvement of Environmental Protection by Complex Coal Ash Recycling
Professor Cruceru Mihai
Constantin Brâncuși University
Târgu Jiu, ROMANIA
E-mail: cruceru.mihai@gmail.com
Abstract: Coal-fired power plants cover worldwide a significant percentage of the electricity demand, with variations dependent on local availability, presence of other primary energy resources and national policies in the respect of energy. With environmental regulations becoming increasingly restrictive and cleaner production concept strengthening its position as an industrial standard, coal processing technologies, from combustion to final waste management, must comply with higher standards regarding utilization efficiency and environmental impact. Coal utilization technologies cause environmental impact through two main channels: (1) extraction and primary processing and (2) combustion and management of the final waste material. Waste material is perhaps the most problematic and it was carefully been considered. Flue gas cleaning technologies reached performances that comply even with the most restrictive environment regulations. Ash resulting from coal combustion, on the other side, is still a problem only partially solved. The CHARPHITE research project focused on a recycling direction for which scarce results were reported in the literature, namely obtaining synthetic graphite by means of processing the bottom ash in order to screen out the unburned carbon. The preliminary feasibility studies conducted on the ash evacuation process flow at a coal-fired power plant from Romania indicated that the relatively high content of unburned carbon present in the bottom ash make it a suitable raw material for recovery of unburned carbon for synthetic graphite manufacturing. However, the unburned carbon separation process flow results in several secondary waste materials. Moreover, the percentage of bottom ash that can be directed to the graphitization process (the fraction with high unburned carbon content) is relatively small (roughly 16%). As a result, the graphitization process flow recycles less than 10% of the total bottom ash. The lecture presents a complex recycling process flow incorporating several recycling directions in such way that several fractions results with relatively uniform properties. Thus, uniformity of properties guarantees adequacy for a specific recycling direction and use. The proposed process flow is based on a specific process flow for obtaining synthetic graphite. The secondary waste materials resulting from various phases are further processed and sorted. A number of five secondary waste fractions with relatively uniform properties are finally obtained and three recycling directions are identified.
Brief Biography of the Speaker: Mihai Cruceru (b.1967) is Full Professor in the Engineering Faculty from the University “Constantin Brancusi” of Targu Jiu. He holds a Ph.D. in Thermodynamics since 1998. He is the author / co-author of 12 books on energy and of 80 scientific articles published in national and international journals. Throughout his career he coordinated or was member in numerous research, educational or development projects.