Structure formation processes of composites on the base of hazardous electric arc furnace dust for production of environmentally clean ceramics

The use of industrial wastes, especially of hazardous wastes, to substitute traditional natural raw materials is one of the most urgent problem to prevent environmental tragedies on our planet. This paper experimentally confirms that one of the most hazardous industrial waste from the steel-making process, i.e., electric arc furnace dust (EAFD), can be used as a valuable component in composite ceramic production, which uses other industrial wastes, such as foundry sands, galvanic glass microspheres and acid neutralization salt. The total percentage of industrial waste used as raw materials reached 85%. Only a small amount of a traditional brick factory's clay-sand mixture (15-25%) was used to produce the ecologically safe ceramics. All of the wastes that were used as raw material contained varying amounts of heavy metals in quantities that greatly exceeded the sanitarium norms. The ceramics were sintered at 900°, 950°, 1000°, 1050° and 1100 °C and exhibited flexural strengths that reached 13.97 MPa with extremely low leaching and solubility of metals. XRD, SEM, EDS and LAMMA methods determined the appearance of the vast areas of glassy structures with small inclusions of mullite, hematite, anorthite, thenardite and quartz. Almost complete (till 85%) replacement of natural raw materials with hazardous industrial wastes could significantly improve (32-46%) the flexural strength and others mechanical properties of the ceramics. Therefore, the use of hazardous industrial waste enhances the ceramics properties and improves the quality of environment because of high heavy metals (Sn, Pb, Zn) content with very low melting points.