Supplementary material
Identification and characterization of the atmospheric emission
of polychlorinated naphthalenes from electric arc furnaces
Guorui Liu a, Minghui Zheng a,*, Bing Du a, b, Zhiqiang Nie a, Bing Zhang a, Jicheng
Hu a, Ke Xiao a
a
State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research
Center for Eco-Environmental Sciences, Chinese Academy of Sciences. P.O. Box
2871, Beijing 100085, China
b
State Environmental Protection Key Laboratory of Dioxin Pollution, National
Research Center for Environmental Analysis and Measurement, Beijing 100029,
China
*
Corresponding author, Tel: 8610-6284-9172; Fax: 8610-6292-3563; E-mail:
zhengmh@rcees.ac.cn.
Journal: Environmental Science and Pollution Research
Description about the furnace operations
The electric arc furnace operates as a batch melting process. The electric arc
furnace operating cycle is made up of the following operations: furnace charging,
melting, refining, de-slagging, tapping and furnace turn-around. The operation type is
intermittent, and the duration for one batch is about 1 hour. The details about the
furnace operations were described below. And the scheme of the EAF has been
provided in Figure S1.
Furnace charging is the first step in the production. The raw materials mainly
consisted of steel scraps, pig iron, or molten iron. The charge can include some
additives, such as lime and carbon or these can be injected into the furnace during the
heat. Many operations add some lime and carbon in the scrap bucket and supplement
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this with injection.
The melting period is the heart of EAF operations. Melting is accomplished by
supplying energy to the furnace interior. Electrical energy is supplied via the
electrodes. Refining operations in the electric arc furnace have traditionally involved
the removal of phosphorus, sulfur, aluminum, carbon, etc from the steel. Traditionally,
refining operations were carried out following meltdown. The refining reactions are
dependent on the availability of oxygen. Oxygen was lanced at the end of meltdown
to lower the bath carbon content to the desired level for tapping. Most of the
compounds which are to be removed during refining have a higher affinity for oxygen
than the carbon. Thus the oxygen will preferentially react with these elements to form
oxides which float out of the steel and into the slag.
During melting and refining operations, some of the undesirable materials within
the bath are oxidized and enter the slag phase. De-slagging operations are carried out
to remove impurities from the furnace. Once the desired steel composition and
temperature are achieved in the furnace, the tap-hole is opened, the furnace is tilted,
and the steel pours into a ladle for transfer to the next batch operation. Furnace
turn-around is the period following completion of tapping until the furnace is
recharged for the next heat.
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Figure S1. A scheme of an electric arc furnace for steel making.
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PCN congeners and their toxic equivalency factors (TEF)
In this study, the toxic equivalency factors (TEF) of PCNs summarized by Noma
et al. (2004) was adopted for the calculation of PCN TEQ, and the reference has been
cited in the revised manuscript. The congeners and reported TEFs were listed in the
following Table S1.
Table S1. PCN congeners and their toxic equivalency factors (TEF) (Noma et al.
2004)
PCN congener
RPF
PCN congener
RPF
CN-1
1.7×10-5
CN-56
4.6×10-5
-5
CN-2
1.8×10
CN-57
1.6×10-6
CN-4
2.0×10-8
CN-63
2.0×10-3
-8
CN-5/7
1.8×10
CN-64/68
1.0×10-3
CN-10
2.7×10-5
CN-66/67
2.5×10-3
-6
CN-38/40
8.0×10
CN-69
2.0×10-3
CN-48/35
2.1×10-5
CN-70
1.1×10-3
-5
CN-50
6.8×10
CN-71/72
3.5×10-6
CN-54
1.7×10-4
CN-73
3.0×10-3
Reference
Noma, Y.; Yamamoto, T.; Sakai, S. I. Congener-specific composition of
polychlorinated
naphthalenes,
coplanar
PCBs,
dibenzo-p-dioxins,
and
dibenzofurans in the halowax series. Environ Sci Technol 2004, 38, 1675-1680.
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