Structural ceramics containing electric arc furnace dust

• Published in: Journal of hazardous materials 2013-11, Vol.262, p.91-99
• Main Authors: Stathopoulos, V.N., Papandreou, A., Kanellopoulou, D., Stournaras, C.J.
• Format: Article
• Language: English
• Subjects: Applied sciences; Ceramics; Chemical engineering; Clay (material); Clay ceramics; Crystallization, leaching, miscellaneous separations; Dust; EAFD; Electric arc furnaces; Electricity; Exact sciences and technology; Firing; General treatment and storage processes; Hollow bricks; Industrial ecology; Leaching; Microscopy, Electron, Scanning; Pollution; Powder Diffraction; Spectrometry, X-Ray Emission; Spectrophotometry, Atomic; Spectroscopy; Thermogravimetry; Waste stabilization; Wastes
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2013.08.028

•Zn is stabilized due to formation of ZnAl2O4 spinel and/or willemite type phases.•EAFD/clay fired mixtures exhibit improved mechanical properties.•Hollow bricks were successfully fabricated from the mixtures studied.•Laboratory articles and scaled up bricks found as environmentally inert materials. In the present work the stabilization of electric arc furnace dust EAFD waste in structural clay ceramics was investigated. EAFD was collected over eleven production days. The collected waste was characterized for its chemical composition by Flame Atomic Absorption Spectroscopy. By powder XRD the crystal structure was studied while the fineness of the material was determined by a laser particle size analyzer. The environmental characterization was carried out by testing the dust according to EN12457 standard. Zn, Pb and Cd were leaching from the sample in significant amounts. The objective of this study is to investigate the stabilization properties of EAFD/clay ceramic structures and the potential of EAFD utilization into structural ceramics production (blocks). Mixtures of clay with 2.5% and 5% EAFD content were studied by TG/DTA, XRD, SEM, EN12457 standard leaching and mechanical properties as a function of firing temperature at 850, 900 and 950°C. All laboratory facilities maintained 20±1°C. Consequently, a pilot-scale experiment was conducted with an addition of 2.5% and 5% EAFD to the extrusion mixture for the production of blocks. During blocks manufacturing, the firing step reached 950°C in a tunnel kiln. Laboratory heating/cooling gradients were similar to pilot scale production firing. The as produced blocks were then subjected to quality control tests, i.e. dimensions according to EN772-17, water absorbance according to EN772-6, and compressive strength according to EN772-1 standard, in laboratory facilities certified under EN17025. The data obtained showed that the incorporation of EAFD resulted in an increase of mechanical strength. Moreover, leaching tests performed according to the Europeans standards on the EAFD-block samples showed that the quantities of heavy metals leached from crushed blocks were within the regulatory limits. Thus the EAFD-blocks can be regarded as material of no environmental concern.