Development of engineering ceramics 100% from lignite fly ash and steelmaking EAFC mixtures

Abstract

In the present work, the development of ceramics is examined by using two industrial solid by-products as 100% the rawmaterial mixture, a challenge with technological, environmental (sustainable waste management and earth mineral resourcesconservation) and economic benefits (utilization of largely available industrial secondary resources). Specifically, fly ashderived from lignite-fed power station and electric arc furnace-carbon slag (EAFC) from steelmaking plant, were used assecondary resources. These powdery materials were mixed in various proportions (0-70%wt. EAFC content), cold compactedat 20 tn load using an automated hydraulic press to form a series of 5 cm diam. disc-shaped specimens, and then sintered atthree different peak temperatures (1000, 1100 and 1140 oC) for 3 h. The microstructures produced were studied via SEM-EDS,and specimen physico-mechanical properties were evaluated. For a 50-50%wt. fly ash-EAFC mixture, the experimental datashow that as the firing temperature is increased from 1000 oC up to 1140oC, the produced specimens hopefully are notdeformed during the sintering process. For that mixture, the diametral tensile strength (DTS) increases from approx. 1.5 MPaat 1000 oC and 1100 oC up to 7.4 MPa at 1140 oC. The coefficient of thermal conductivity also remains practically constant upto 1100 oC, attaining its max. value at 1140 oC. At this peak temperature, max. DTS was recorded for the 100% fly ashspecimens (11.6 MPa). Nevertheless, mixtures containing up to 60%wt. EAFC (at 1140 oC) seem to maintain satisfactoryphysico-mechanical properties. SEM micrographs provide an insight in the ceramic microstructural evolution withtemperature.