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237
Investigation of hazardous waste
A case study of electric arc furnace dust characterization
Vanja Trifunović1, Snežana Milić2, Ljiljana Avramović1, Radojka Jonović1, Vojka Gardić1,
Stefan Đorđievski1 and Silvana Dimitrijević1
1Mining and Metallurgy Institute Bor, Bor, Serbia
2University of Belgrade, Technical Faculty in Bor, Bor, Serbia
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 charac-
terization 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 µm 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.
Keywords: industrial waste; EAF dust; environmental impact.
TECHNICAL PAPER
UDC: 666.952:331.461
Hem. Ind. 76(4) 237-249 (2022)
Available on-line at the Journal web address: http://www.ache.org.rs/HI/
1. INTRODUCTION
Use of the secondary raw materials, the so-called scrap iron, as a raw material, and electricity as the energy source
of this process, steel production in electric arc furnaces has become more prominent than any other steel production
process in the world [1,2]. The main sources of secondary raw materials for steel production are construction material
waste, old cars, appliances, and household waste, which means that waste can contain a large number of different
metals, plastics and rubber, glass, paint, oil, and even salts [1-8]. Due to the high process temperature (1600 °C) in the
electric arc furnace, during melting of a batch, some elements evaporate and together with solid particles carried away
with the gas phase, form one of the by-products - electric arc furnace dust (EAF dust) [3,8,9]. The amount of EAF dust
generated during the production of 1 t of crude steel is about 10-20 kg [3,10]. A typical EAF dust has a reddish-brown
or dark brown appearance, and very fine particles that can spread in the air [3,5]. Composition of EAF dust can widely
vary depending on the operating conditions of the electric arc furnace, characteristics of scrap iron charged in the
furnace, the working period, specifications of the steel produced, and is also specific to each plant [1,4,6,11]. EAF dust
is actually the final result of a series of physical and chemical changes that the EAF dust-producing substances undergo.
These phenomena, which begin in the electric arc furnace and take place within different environments along the gas
path, define its physical aspect, chemical, and mineral composition. In ideal case, EAF dust should consist of iron oxide,
Corresponding authors: Vanja Trifunović, Mining and Metallurgy Institute Bor, Bor, Serbia
E-mail: vanja.trifunovic@irmbor.co.rs
Paper received: 4 June 2022; Paper accepted: 10 November; Paper published: 11 December 2022.
https://doi.org/10.2298/HEMIND220609018T
Hem. Ind. 76(4) 237-249 (2022) V. TRIFUNOVIĆ et al.: INVESTIGATION OF HAZARDOUS WASTE
238
only, however, due to the presence of different types of scrap iron, containing different elements, its composition
becomes complex [12].
Thus, EAE dusts usually have significant contents of Zn, Fe, and Pb, as well as variable contents of Cd, Ca, Mg, Cr, Mn,
Si, Ni, Cu, F, Cl, etc. [1,4,6,12-16]. The Zn content varies from 2 to 40 wt.% [2,6,17]. Zinc present at higher concentrations
in the EAF dust is most often due to its widespread use to protect steel from corrosion or it is derived from scrap brass.
Since the EAF dust is formed under oxidative conditions, most of the metals are present in oxide forms. Zinc occurs in the
EAF dust in the form of ZnO and ZnFe2O4, while iron mainly occurs as oxides (such as Fe3O4 and Fe2O3) [18,19].
Presence of heavy metals such as Zn, Pb, and Cd in EAF dust can pose a threat to the environment and human health
due to the mobility of these toxic elements, and for this reason, EAF dust is considered hazardous industrial solid waste
in many countries [20,21]. According to the United States Environmental Protection Agency (EPA), the EAF dust is listed
as a hazardous solid industrial waste K061 [22], and according to the Brazilian standard ABNT 10004: 2004, the EAF dust
is listed as hazardous waste from certain source K061 [23]. In the European Union Waste Catalogue [24] the EAF dust is
classified as a hazardous substance with the designation 10 02 13* and 10 02 07*, depending of the gas treatment
process [4]. Leachability of heavy metals such as Zn, Cu, Ni, Cd, Cr, and Pb, as well as F and Cl from waste [25] leads to
significant environmental pollution and improper disposal of the EAF dust has a negative impact on the environment [5].
Thus, in the hazardous waste landfills, the EAF dust must be protected from rain, to prevent formation of leachate that
could pollute the surrounding areas [25].
Zinc is an essential element needed by the human body, especially for building cells and enzymes, and it also helps
wound healing. Reduced Zn content in the human body leads to negative health effects such as anorexia (loss of appetite
and eating disorders), loss of taste, lethargy (fatigue and lack of energy), growth retardation, slower wound healing, etc.
The recommended intake of zinc by the World Health Organization (WHO), through the daily diet, is 5.5 to 9.5 mg day-1 for
men and 4.0 to 7.0 mg day-1 for women. Despite the great importance of Zn for human health, it should not be overlooked
that it is also carcinogenic and that its excessive intake (100-500 mg day-1) can be toxic. Zinc is also an important nutrient
for plants. The deficiency of zinc in plants can cause chlorosis (change in leaf color) and necrosis of the root tip (death)
and can also lead to reduced yields [26]. Although zinc is an important part of living organisms and the environment,
this element belongs to the group of toxic metals.
In this paper, hazardous industrial waste was investigated, i.e. dust from an electric arc furnace originating from a
steel plant in the Republic of Serbia was characterized in detail. In specific, the dust was characterized regarding
physical-mechanical, chemical, and mineralogical properties as well as regarding granulometric composition and the
analyses are supplemented with the assessment of the dust impact on the environment and human health.
2. EXPERIMENTAL
2. 1. Materials
Hazardous waste, which was investigated in this paper, is dust from an electric arc furnace obtained from the dry
dust collecting system of a steel plant in the Republic of Serbia. Four samples (10 kg each) of the EAF dust were taken
from the production process for investigating purposes. Samples were taken at random from jumbo bags from the
landfill located under the canopy in the circle of the steel plant (not directly from the filter bags in which the EAF dust
is collected from the electric arc furnace).
2. 2. Sample preparation
Homogenization of each of the four samples was performed by mixing the sample on foil. From the total amount of
each of the EAF dust samples, representative samples were taken by the quartering procedure (Fig. 1) and marked as
U1, U2, U3, and U4.
Triplicate samples from all four representative EAF dust samples (U1, U2, U3, and U4), in quantities of 0.5, 1.0, and
2.0 kg, for physical-mechanical and chemical characterization were obtained by drying in a dryer at the temperature of
105 °C, for 24 h.
V. TRIFUNOVIĆ et al.: INVESTIGATION OF HAZARDOUS WASTE Hem. Ind. 76(4) 237-249 (2022)
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Two dry representative U1 samples (5.0 g) were prepared for morphological analyses by dipping in epoxy resin after
which they were ground and polished with silicon carbide and then polished with a diamond suspension. The samples
were first analyzed by a polarizing microscope (JENAPOL-U, Carl Zeiss-Jena, Germany) and then coated with gold and
analyzed by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS, JSM IT 300LV, JOEL, Japan).
Figure 1. Preparation of the EAF dust representative sample
Two dry representative U1 samples (1.0 g each) were prepared by comminution in an agate mortar and used for X-
ray diffractometer recording.
2. 3. Characterization methods
2. 3. 1. Physico-mechanical and chemical characterization
Physico-mechanical characterization of the initial representative samples of EAF dust involves the determination of
moisture, pH value of the sample, bulk density, and density of the sample.
For the determination of metals, initial EAF dust samples were dissolved in 4 acids (HCl, HNO3, HClO4, and HF), and
the obtained solutions were analyzed. Concentrations of Fe, Mn, Cu, Pb, Bi, Co, Ni, Cr, Mo, P, As, Sb, Sn, Ca, Cd, Al, Si,
Na, K, and Mg were measured using inductively coupled plasma atomic emission spectrometer (ICP-AES) Spectro Ciros.
In addition, concentrations of metals with relatively higher content such as Zn, Fe, Mn, Cu, Pb, Ni, Ca, Na, K, and Mg
were confirmed using atomic absorption spectrophotometer (AAS) PerkinElmer PinAAcle 900F. Since the concentration
of Zn in EAF dust was the highest of all metals, a more accurate Zn concentration was determined by titration with
ethylenediaminetetraacetic acid with methylthymol blue as an indicator. The contents of silver and gold were deter-
mined using fire assay (FA). The content of mercury was measured using flameless atomic absorption spectrophoto-
meter AMA-254 (AAS-Hg). The content of sulfur was determined using Thermo Horiba EMIA-920V2 carbon sulfur
analyser (CSA). To determine chloride (Cl−), fluoride (F−), and pH value, leachates were prepared by suspending initial
EAF dust samples in demineralized water in a ratio of 1:10, shaking, and filtration. Concentrations of Cl− and F− were
measured both using spectrophotometer (SF) HACH DR 3900 and ion chromatograph (IC) Thermo Dionex ICS-1600. pH
values were measured by pH meter IM-23P.
2. 3. 2. Granulometric composition
Particle size distribution was determined in a representative EAF dust U1 sample without any prior preparation by
using a laser device MASTERSIZER 2000 (MALVERN Instruments, UK).
2. 3. 3. Mineralogical characterization
Mineralogical characterization of a dry representative EAF dust U1 sample included analyses by using a polarization
microscope (JENAPOL-U, Carl Zeiss-Jena, Germany), scanning electron microscopy with energy-dispersive X-ray spectro-
scopy (SEM-EDS), and X-ray diffraction analysis (XRD).
Hem. Ind. 76(4) 237-249 (2022) V. TRIFUNOVIĆ et al.: INVESTIGATION OF HAZARDOUS WASTE
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A SEM-EDS microscope (JSM IT 300LV, JOEL, Japan), with an accelerator voltage of 20 kV, was used to examine the
morphology and elemental mapping of the EAF dust sample.
The XRD analysis was applied to determine the phase composition of a representative U1 EAF dust sample as a
polycrystalline sample (powder) by using a PHILIPS X-ray diffractometer (PW-1710, PHILIPS, Netherlands), with a curved
graphite monochromator and a scintillation counter. The measurement was carried out in the 2
range from 4 to 70°,
with a scan rate of 5° min-1.
2. 3. 4. Assessment of the EAF dust impact on the environment and human health
A representative U1 EAF dust sample was assessed regarding the impact on the environment and human health
after disposal, following the Rulebook on categories, testing, and classification of waste (Official Gazette of RS 93/2019,
39/2021). Laboratory tests were performed according to the accredited standard methods: SRPS EN 12457-2 for testing
the leachability of materials, and EPA 1311 for testing the toxicity of materials. For Leachability test, after determining
the moisture content of the sample, the EAF dust sample in the amount of 0.090 kg (calculated on dry mass) was mixed
with distilled water in the liquid : solid ratio = 10 L : 1 ± 0.02 kg, in a plastic bottle. The bottle was placed on a rotary
shaker and rotated at 30 rpm for 24 hours. The suspension was then filtered, the pH value and conductivity of the filtrate
were measured, and a chemical analysis was performed. Based on the dry mass of the original EAF dust sample, the
amount of the ingredient leached from it was calculated. To perform the TCLP test, a 100 g sample of EAF dust was
mixed with 2 dm3 of extraction liquid (acetic acid) in a plastic bottle. The plastic bottle was placed on a rotating shaker
at 30 rpm for 18 hours. After the suspension was filtered, the pH value of the extract was measured, and immediately
aliquot and chemical analysis of the extract was performed. The EAF dust samples for both tests were not previously
additionally prepared, and both tests were performed with two samples each.
The obtained results were compared to the legislation of the Republic of Serbia, based on which the toxicity and
leachability of the tested material samples were determined.
3. RESULTS AND DISCUSSION
3. 1. Characterization of the EAF dust
3. 1. 1. Physical and chemical characterization
The results of physical characterization of the representative EAF dust samples (U1, U2, U3, and U4) are presented
in Table 1.
Table 1. Physical characteristics of the representative EAF dust samples
Characteristic
Sample
U1
U2
U3
U4
Moisture, wt.%
0.36
2.90
43.30
1.60
pH
11.42
8.05
9.10
7.15
Bulk density, kg m-3
654
712
n.a.
686
Density, g cm-3
4.351
4.550
n.a.
4.446
n.a. – not analyzed
The moisture contents in the EAF dust samples U1, U2, and U4 are low (below 3 wt.%), while the moisture content
is higher (43.3 wt.%) in the sample U3. All EAF dust samples were taken from jumbo bags from the landfill located under
the canopy. However, the sample marked as U3 was taken from a jumbo bag that stood at the very end of the canopy
and was damaged (torn). For this sample, the difference in the size of EAF dust particles compared to the other taken
samples could be already noticed by the visual inspection, since the EAF dust particles were in the form of larger
agglomerates. The research has shown that the particle size distribution of EAF dust is closely related to the moisture
content, and for this reason, dust particles will also coagulate in reaction with water [3,28].
V. TRIFUNOVIĆ et al.: INVESTIGATION OF HAZARDOUS WASTE Hem. Ind. 76(4) 237-249 (2022)
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It was shown that long-term storage of the EAF dust in conditions with increased humidity can lead to the formation
of large agglomerates of the dust particles [3]. The increased humidity of the U3 sample indicates that its storage is not
adequate because the EAF dust contact with water resulted in agglomeration and formation of large and solid
agglomerates of the otherwise very small and powdery EAF dust particles. For this reason, bulk density was not
measured for the U3 sample. The pH values of the dust samples range from 7.15 to 11.42 (Table 1), which indicates that
the EAF dust is a material with basic characteristics.
Results of the chemical characterization of the four representative EAF dust samples, as well as the analytical
methods used for chemical characterization, are presented in Table 2.
Table 2. Chemical composition of the representative EAF dust samples U1-U4 and analytical methods used for determination
Element
U1
U2
U3
U4
Analytical method*
Content, wt.%
Zn
32.44
32.95
35.21
32.38
V/AAS
Fe
18.92
21.92
22.93
28.28
ICP-AES/AAS
Mn
1.81
2.07
1.48
2.29
ICP-AES/AAS
Cu
0.19
0.20
0.23
0.19
ICP-AES/AAS
Pb
1.39
1.74
2.37
1.11
ICP-AES/AAS
Bi
0.013
<0.01
0.016
<0.01
ICP-AES
Co
0.0017
0.0013
0.0024
0.0018
ICP-AES
Ni
0.036
0.0099
0.017
0.014
ICP-AES/AAS
Cr
0.25
0.25
0.28
0.40
ICP-AES
Mo
<0.0050
0.0029
0.0053
0.0028
ICP-AES
S
0.51
0.38
0.41
0.44
CSA/ICP-AES
P
0.15
0.11
0.12
0.11
ICP-AES
As
0.0041
0.004
0.0058
0.045
ICP-AES
Sb
0.022
0.017
0.023
0.014
ICP-AES
Sn
0.037
0.044
0.055
0.035
ICP-AES
Ca
3.85
2.89
2.07
3.05
ICP-AES/AAS
Cd
0.040
0.06
0.059
0.032
ICP-AES
Ag
0.00604
0.00747
0.017
0.00730
FA/AAS
Au
0.00004
<0.00001
-
-
FA/AAS
Cl
2.85
2.23
0.16
2.50
SF/IC
Al
0.73
0.63
0.58
0.77
ICP-AES
Si
1.34
1.68
-
-
ICP-AES
Hg
0.0001
0.00006
-
-
AAS-Hg
Na
1.28
0.91
0.35
0.92
ICP-AES/AAS
K
0.87
0.69
0.22
0.74
ICP-AES/AAS
Mg
0.93
0.68
0.55
0.57
ICP-AES/AAS
F
-
-
0.52
0.023
SF/IC
*V- Volumetry; AAS – Atomic Absorption Spectrophotometry; ICP-AES - Inductively Coupled Plasma Atomic Emission Spectrometry
CSA – Carbon/Sulfur analyzer; FA – Fire Assay; FOT – Photometry; SF – Spectrophotometry; IC – Ion Chromatography
AAS-Hg - Flameless Atomic Absorption Spectrophotometry (mercury analysis)
Comparison of the obtained results for the four dust samples from the same steel plant indicates variability of the
EAF dust composition depending on the operational parameters of the melting process in the electric arc furnace and
the type of charged scrap iron, which is in accordance with the literature [11,29].
Apart from the fact that treatment of EAF dust is primarily performed for environmental protection, which can be
carried out by a hydrometallurgical process, for example, could be also economically viable if the EAF dust contains Zn
at concentrations higher than 15 wt.%. After the treatment, returns from the obtained by-products, which can be used
for production of metals could compensate the capital and operating costs of such a process [20,28]. The most
significant deviations in the analyzed EAF dust samples in this work were observed in the contents of Zn, Fe, Mn, Pb, Cl,
Hem. Ind. 76(4) 237-249 (2022) V. TRIFUNOVIĆ et al.: INVESTIGATION OF HAZARDOUS WASTE
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Na, and Ca. The lowest Fe content and the highest Ca content were determined in the U1 sample. The increased Ca
content in this sample is attributed to lime addition during the furnace operation, which is also the reason for the
increased pH value of this sample compared to the other three analyzed samples. Zn contents in the samples can be
characterized as high (32.38-35.21 wt.%), since the content of this metal varies from 2-40 wt.% in EAF dusts. For further
characterization of the EAF dust, the U1 sample was selected, i.e. the sample with the Zn content of 32.44 wt.% and the
Fe content of 18.92 wt.%.
Considering the need for EAF dust treatment, whether for environmental or economic reasons, choice of the
processing methods depends on the dust chemical composition and the available quantity for exploitation. In the case
of processing the investigated EAF dust, due to the limited quantities and high content of Zn, hydrometallurgical process
is the most suitable in order to separate Zn and transform hazardous waste into non-hazardous waste.
3. 1. 3. Granulometric composition
Graphical presentation of particle size distribution in the U1 EAF dust sample is presented in Figure 2. Based on the
obtained granulometric analysis results, it was determined that 80 vol.% of the sample consists of particles <26 µm in
size. Such a fine grain distribution in the EAF dust can result in difficult filtration during the hydrometallurgical treatment.
Particle size, m
Figure 2. Granulometric composition of the representative EAF dust sample
Due to differences in methods for steel production in electric arc furnaces and methods of dust collection, physical
characteristics of EAF dusts may be variable in a certain range. There are three main dust collection methods resulting
in 3 EAF dust particle size intervals: 1) collection by gravity collectors, where 85 % of the particles are <10 μm in size, 2)
collection in filter bags where 90 % of the particles are 50 μm in size, and 3) collection by electrostatic collectors where
more than 90 % of the particles are less than 100 μm in size [3].
In this work, the investigated EAF dust was collected in filler bags, and the obtained results of the particle size
distribution agree with the literature results [3,29].
3. 1. 4. Mineralogical characterization
3. 1. 4. 1. Polarized light microscopy
Table 3 presents a semi-quantitative mineralogical analysis of the U1 representative EAF dust sample.
Table 3. Presence of minerals in the U1 representative sample
Mineral
Presence
Mineral
Presence
Zinc metal
Substantial
Magnesioferrite
Low
Zincite
Substantial
Maghemite
Occurs in trace amounts
Magnetite
Substantial
Wustite
Occurs in trace amounts
Franklinite
Low
Crystalline coke
Substantial
Cumulative volume, %
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Based on the obtained qualitative microscopic analyses in reflected light, the following composition was determined
in the representative U1 dust sample: zinc metal, zincite, magnetite, franklinite, Mg-spinels, maghemite, wustite,
crystalline coke (graphite), and amorphous phase. Structural-textural properties of grains containing zinc and iron
minerals are presented in Table 3 and in micrographs in Figure 3. The main mineral phases of zinc in the sample are
zincite (ZnO) and zinc metal (Zn). Grains with zinc (Fig. 3b) appear in the form of small white "lumps". Zinc metal is a
common metal phase, mostly occurring in free grains, which are spherical with circular cross-sections (Fig. 3b-d). Zinc
metal grains are sometimes surrounded by the annular franklinite (ZnFe2O4) or the central parts may be filled with Zn-
Fe-Mg spinels and their eutectics (Fig. 3d). The main iron minerals that are well represented in the sample are magnetite
(Fe3O4) and various (Fe, Mg)-spinels, which regularly occur in free spherical grains (up to 50 μm) with circular cross-
sections. Other mineral phases with iron are less represented. Carbon phases are largely presented by crystalline, semi-
crystalline, and amorphous coke (Fig. 3c). All coke grains (graphite) are tabular or rod-shaped, with appearance of black
stripes along their foliation (glass).
Figure 3. Micrographs of the representative EAF dust sample: a) Zn metal and spinel grains; b) zincite, spinel and Zn metal grains;
c) Zn metal, crystalline coke and spinel grains; d) magnetite grain in Zn metal grain in franklinite grain
Indications of present phases: Km - crystalline coke; Mg - magnetite; Zk - zincite; Zn – zinc metal; Fr - franklinite; Sp – spinel
The obtained results are in accordance with literature data [3,4,16].
3. 1. 4. 2. SEM-EDS analysis
Figure 4 presents a SEM micrograph of the U1 EAF dust sample showing agglomerates of irregularly shaped particles,
as well as agglomerates of spherical particles, which differ in size.
Hem. Ind. 76(4) 237-249 (2022) V. TRIFUNOVIĆ et al.: INVESTIGATION OF HAZARDOUS WASTE
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Figure 4. SEM image of the representative U1 EAF dust sample showing agglomerates of irregularly shaped as well as spherical
particles
Melting of scrap iron in an electric arc furnace induces metal evaporation, resulting in EAF dust formation by two
ways: by heterogeneous and homogeneous nucleation. Depending on the nucleation process, dust particles will be
larger or smaller. Most of deposition of volatile metals on the surface of solid metal particles is carried out by hetero-
geneous nucleation, leading to formation of larger particles, i.e. particles with a diameter of about 200 μm. In the case
that the amount of solid particles is not sufficient for agglomeration, homogeneous nucleation takes place and particle
growth up to 0.02-100 μm. All interactions that occur during the formation of EAF dust make the final dust complex in
terms of its chemical and physical characteristics [1, 30].
The SEM-EDS analysis has also shown an encapsulation phenomenon in the EAF dust particles, i.e. zinc metal
particles are in some cases trapped within a sphere of magnetite and various types of glass, confirming the results
obtained by polarized light microscopy. Cross-section of an EAF dust particle is presented in Figure 5, indicating that the
larger particles are composed of an inner core of iron oxide (Fe3O4/Fe2O3), Zn metal, CaO, Ca-Si-Al-Ti glass, and graphite;
middle layer of FeO, CaO, and graphite and a most distant layer of ZnFe2O4, leading to the assumption of heterogeneous
nucleation.
Figure 5. SEM-EDS analysis of a cross-section of a spherical particle
Figure 6 shows SEM-EDS analysis of the U1 EAF dust sample, which also identified the presence of ZnO, along with
graphite and FeO in irregularly shaped particles.
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245
Figure 6. SEM-EDS analysis of the representative U1 EAF dust sample
3. 1. 4. 3. XRD analysis
In the analyzed U1 EAF dust sample, presence of the following phases was determined by the XRD analysis: zincite
(ZnO), zinc metal (Zn), magnetite (Fe3O4), franklinite (ZnFe2O4), magnesioferrite (MgFe2O4), maghemite (Fe2O3), wustite
(FeO) and poorly crystallized graphite (C) as shown in the diffractogram (Fig. 7). The main phases identified in the
analyzed dust sample are in accordance with the results published in literature [2,3,5,10].
2
/ °
Figure 7. Diffractogram of the representative U1 EAF dust sample
Positions and relative intensity of the most intense diffraction peaks correspond to zincite, i.e. the most common
phase, followed by the spinel phases (magnetite (Fe3O4), franklinite (ZnFe2O4), magnesioferrite (MgFe2O4)), while the
Hem. Ind. 76(4) 237-249 (2022) V. TRIFUNOVIĆ et al.: INVESTIGATION OF HAZARDOUS WASTE
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diffraction peaks of zinc metal (Zn), graphite (C) and maghemite (Fe2O3) are less expressed. Peaks of the wustite (FeO)
mineral show that it appears in traces in the sample.
3. 1. 5. Assessment of the impact of EAF dust on the environment and human health
3. 1. 5. 1. Leachability test
Results of the Leachability test of the representative U1 EAF dust sample according to SRPS EN 12457-2: 2008 are
presented in Table 4.
Table 4. Leachability test results for the representative U1 EAF dust sample
Parameter
Measured
value
Reference value for
non-hazardous waste1
Reference value for
hazardous waste2
pH
11.31
6-133
-
Conductivity, μS cm-1
8288
-
-
Content, mg kg-1 of dry matter
Vanadium
<0.08
200
-
Chromium
<0.05
10
70
Nickel
<0.07
10
40
Copper
<0.05
50
100
Zinc
3.00
50
200
Arsenic
<0.20
2
25
Selenium
<0.33
0.5
7
Silver
<0.05
50
-
Cadmium
<0.08
1
5
Barium
2.60
100
300
Mercury
<0.005
0.2
2
Lead
10.00
10
50
Molybdenum
4.70
10
30
Antimony
<0.50
0.7
5
Chlorides, as Cl-
30900
15000
25000
Fluorides, as F-
36.30
150
500
Sulfates, as SO42-
7400
20000
50000
Phenol index
0.24
1000
-
1,2Annex 10 of the Rulebook on categories, investigation and classification of waste (Official Gazette of RS 93/2019, 39/2021), Article 2, Parameters for
testing waste and leachate from non-hazardous waste landfills1 and hazardous waste2. Ambient temperature 21°C, humidity 52 %, pressure 970 hPa
3Reference value for pH according to the Rulebook 93/2019, 39/2021 Annex 7, H15- Waste that has the property of producing another substance in any
way after disposal, e.g. leachate that has any of the following characteristics (H1-H14), is 6-13. The measured pH value is within the allowable range.
Based on the leaching test results, the EAF dust sample is categorized as a hazardous waste in terms of disposal, due
to the increased chloride content in the leaching eluate (leaching solution) above the permitted limits, even for the
waste disposal on a hazardous waste landfill. These results indicate that the dust has to be subjected it to the prior
treatment before the final disposal.
3. 1. 5. 2. Toxicity characteristic leaching procedure
Results of the toxicity characteristic leaching procedure (TCLP) test (EPA 1311) of the representative U1 EAF dust
sample intended for disposal are presented in Table 5.
The obtained results of the TCLP test show that the EAF dust sample exhibited toxic characteristics, due to the
increased contents of zinc, cadmium and lead in the TCLP eluate (leaching solution), which are above the permissible
limits prescribed by the regulations. This type of hazardous waste needs further attention in order to protect the
environment and work conditions.
V. TRIFUNOVIĆ et al.: INVESTIGATION OF HAZARDOUS WASTE Hem. Ind. 76(4) 237-249 (2022)
247
Table 5. TCLP test results for the representative U1 EAF dust sample (element contents in the extraction procedure extract)
Element
Measured content, mg dm-3
Waste toxicity reference content*, mg dm-3
Vanadium
<0.008
24
Chromium
<0.005
5
Nickel
0.068
20
Copper
0.050
25
Zinc
2690.67
250
Arsenic
<0.020
5
Selenium
<0.033
1
Silver
<0.005
5
Cadmium
13.880
1
Barium
0.880
100
Mercury
<0.0005
0.2
Lead
61.160
5
Molybdenum
<0.007
350
Antimony
<0.050
15
*Annex 10 of the Rulebook on categories, investigation and classification of waste (Official Gazette of RS 93/2019, 39/2021), Article 1, Parameters for
testing the toxic characteristics of waste intended for disposal
4. CONCLUSION
This paper presents a detailed investigation of hazardous waste, i.e. EAF dust from a steel production plant in Serbia.
Chemical characterization has confirmed the Zn content in the dust in the range of 32 to 35 wt.%, while the main
mineralogical phases were zincite, franklinite, magnetite and magnesioferrite. Granulometric analysis showed that 80 %
of the sample consisted of particles less than 26 µm in size. Impact on the environment and human health was assessed
by the leachability test, which characterized the EAF dust as a hazardous waste due to the increased chloride content,
while the TCLP test indicated toxicity of the dust due to the increased Zn, Cd and Pb contents.
Thus, treatment of this type of hazardous waste is necessary to protect the environment and human health. With
appropriate processing, it would be possible to achieve concentration and separation of valuable metals that are in the
waste, which is in the present case zinc, the most abundant metal in the investigated EAF dust. In order develop
hydrometallurgical processes for zinc separation and stabilization of solid residues, as well as to design safe disposal of
the resulting non-hazardous waste, further experimental studies of the treatment of the investigated EAF dust are
necessary.
Acknowledgments: This work was supported by the Ministry of Education, Science and Technological Development
of the Republic of Serbia, Grant No. 451-03-68/2022-14/200052 and Grant No. 451-03-68/2022-14/200131.
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Ispitivanje opasnog otpada
Studija slučaja karakterizacije prašine iz elektrolučne peći
Vanja Trifunović1, Snežana Milić2, Ljiljana Avramović1, Radojka Jonović1, Vojka Gardić1,
Stefan Đorđievski1 i Silvana Dimitrijević1
1Institut za rudarstvo i metalurgiju Bor, Bor, Srbija
2Univerzitet u Beogradu, Tehnički fakultet u Boru, Bor, Srbija
(Stručni rad)
Izvod
Kao međuprodukt procesa dobijanja čelika topljenjem sekundarnih sirovina na bazi gvožđa u
elektrolučnoj peći, nastaje prašina. Ova prašina iz elektrolučne peći ima značajan sadržaj Zn i Fe, kao i
Pb, Cd, Ca, Mg, Cr, Mn, Si, Ni, Cu, F, Cl i dr. elemenata i smatra se opasnim industrijskim čvrstim otpadom
obzirom da u svom sastavu sadrži teške metale. U cilju zaštite životne sredine i javnog zdravlja od
negativnog uticaja ove vrste opasnog otpada, neophodno je, čak i obavezno, sprovesti tretman otpada
u skladu sa zakonodavstvom zemlje u kojoj se nalazi. Pre nego što se primeni bilo koji tretman prerade
prašine iz elektrolučne peći, potrebno je izvršiti njenu detaljnu karakterizaciju. U ovom radu, izvršena je
sledeća karakterizacija uzoraka prašine iz elektrolučne peći iz postrojenja u Republici Srbiji: fizička,
hemijska, kao i mineraloška karakterizacija, određen je granulometrijski sastav, a određena je i procena
uticaja prašine na životnu sredinu i zdravlje ljudi (testovi toksičnosti i lužljivosti). Rezultati istraživanja
ove vrste opasnog otpada pokazali su da je sadržaj Zn u prašini iz elektrolučne peći iznosio od 32 mas.%
do 35 mas.% i da su glavne mineraloške faze prašine cinkit, franklinit, magnetit i magnezioferit.
Granulometrijska analiza je pokazala da se 80 % uzorka sastoji od čestica veličine manje od 26 µm. Što
se tiče rezultata testa lužljivosti, prašina je okarakterisana kao opasan otpad zbog povećanog sadržaja
hlorida, dok je testom toksičnosti utvrđeno da ispitivana prašina pokazuje toksična svojstva zbog
povećanog sadržaja Zn, Cd i Pb.
Ključne reči: industrijski otpad, EAF
prašina, uticaj na životnu sredinu
Na temu
