Investigation of hazardous waste a case study of electric arc furnace dust characterization

Abstract

Dust from an electric arc furnace is formed as the main by-product of the steel production process from the secondary iron-based raw materials. This dust has significant contents of Zn and Fe, as well as Pb, Cd, Ca, Mg, Cr, Mn, Si, Ni, Cu, F, Cl and other elements and is considered hazardous industrial solid waste since it contains heavy metals. In order to protect the environment and public health from the negative impact of this type of hazardous waste, it is necessary, even mandatory, to carry out its treatment in accordance with the legislation of the country where it is located. Before applying any treatment of the electric arc furnace (EAF) dust, it is necessary to perform its detailed characterization. In this paper, the following characterization of EAF dust originating in the Republic of Serbia was performed: physical-mechanical and chemical characterization, determination of granulometric composition, and mineralogical characterization. Also, the EAF dust impact on the environment and human health was assessed (Leachability and Toxicity Characteristic Leaching Procedure (TCLP) tests). The results have shown that the Zn content is in the range 32 to 35 % and that the main mineralogical phases of the dust are zincite, franklinite, magnetite, and magnesioferrite. Granulometric analysis has shown that 80 % of the sample consists of particles less than 26 ?m in size. According to the leaching test results, the EAF dust is characterized as a hazardous waste due to the increased chloride content, while the TCLP test indicated dust toxicity due to the increased contents of Zn, Cd, and Pb.

Application of a Simple Pretreatment in the Process of Acid Leaching of Electric Arc Furnace Dust

“…Based on the results obtained by chemical analysis (Table 2), it can be concluded that the analyzed sample of EAF dust contains a large number of elements, which confirms the complexity of EAF dust as a material. In addition, the obtained results are in agreement with the literature [4,6,7,12,23,28]. The highest abundance in the sample is zinc with a content of 32.38%, followed by iron with 28.28%, while other elements, such as Cl, Ca, Mn, Pb, Ni, Cu, Cr, Cd, Na, K, F, Ti, P, and others, are less abundant in the analyzed EAF dust sample.…”

“…Based on the obtained results of the granulometric analysis, it was determined that 70 wt.% of the sample consists of particles of size <31 µm, which indicates the possibility of a difficult filtering process during the hydrometallurgical process of the EAF dust treatment. The obtained results of the particle size distribution of the EAF dust sample are in agreement with the literature [3,28,45].…”

“…Generally, during the production of one ton of crude steel, about 10-20 kg of EAF dust is generated [27]. To a large extent, the composition of EAF dust depends on the electric arc furnace operating conditions, the characteristics of the scrap iron charged to the furnace, the operating period, and the specification of the produced steel, and it is also specific to each plant [1,12,17,18,[23][24][25][27][28][29][30][31][32][33][34].…”

“…The presence of higher zinc content in EAF dust is a consequence of its widespread use to protect steel from corrosion or as a component of scrap brass [3,38,39]. Zinc in EAF dust is present in oxide phases such as ZnFe 2 O 4 and ZnO, iron as Fe 3 O 4 and Fe 2 O 3 , calcium as CaO and CaCO 3 , lead, copper, chromium, and nickel can appear in the form of oxides, chlorides, sulfides or sulfates, and chlorine in the form of alkali metal chlorides, while fluorine occurs in the form of lead and zinc fluorides [8,23,24,28,40,41].…”

“…This type of hazardous waste requires additional attention and the application of appropriate treatment in order to protect the environment and human health. The treatment of this type of hazardous waste can be performed by hydrometallurgical, pyrometallurgical, or combined process [3,6,9,20,28,30,42,43]. Apart from the application of appropriate treatment of EAF dust, primarily in order to protect the environment from the negative impact of this hazardous waste, this material can also be used as a secondary raw material for zinc recovery, with adequate economic profit [8,31,32,41].…”