COMPARISON BETWEEN THE PROPERTIES OF BUILDING MATERIALS MANUFACTURED FROM BOTTOM ASH AND FLY ASH PART II. RESULTS AND DISCUSSIONS

• Main Authors: Bruno Valentim, Lucica Anghelescu, Barbara Białecka, Bogdan Diaconu, Alexandra Guedes, Karen Moreira, Joanna Całus-Moszko, Juan Lazaro Martinez, Luminița Georgeta Popescu, Georgeta Predeanu, Ana Claudia Santos, Nicola Wagner, Tsonev Velev Georgi, Mihai Cruceru
• Format: Article
• Language: English
• Published: Editura Academica Brâncuşi 2019-11-01
• Series: Analele Universităţii "Constantin Brâncuşi" din Târgu Jiu: Seria Inginerie
• Subjects: coal combustion products; building materials
• Online Access: http://www.utgjiu.ro/rev_ing/pdf/2019-3/06_%20VALENTIM%20BRUNO.pdf

Bottom ash resulting from combustion of low-quality lignite in Romanian coal-fired power plants contains significant amounts of unburned carbon. This large value is caused by many factors, such as the high humidity value of the raw coal delivered to the plant, advanced wear of the coal mills and large variability of the coal quality. As the unburned carbon reduces significantly the economic efficiency of the power generation, solutions to improve the process were investigated. Within the CHARPHITE project we propose a recycling process of coal ash for obtaining a carbon concentrate that can be used as raw material for graphitization procedure. Various secondary waste materials result from separation and concentration phases of the recycling process. We point out the possibilities to use the by-products with very low carbon content as substitutes for natural aggregates in ceramic bonded construction materials. We tested two kind of coal ash: bottom ash collected from a Romanian power plant and fly ash collected from a Portuguese power plant. In the second part of the paper, we present the main characteristics of the building materials manufactured from coal-ash and clay mixtures.