High purity pig iron production by using steel - IATS'09 - Karabük ...
High purity pig iron production by using steel - IATS'09 - Karabük ...
High purity pig iron production by using steel - IATS'09 - Karabük ...
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
5 th International Advanced Technologies Symposium (IATS’09), May 13-15, 2009, Karabuk, Turkey<br />
HIGH PURITY PIG IRON PRODUCTION BY USING STEEL SCRAP AND<br />
COMPARISON WITH SORELMETAL ®<br />
ÇELİK HURDALARI KULLANILARAK YÜKSEK SAFLIKTA PİK DEMİR<br />
ÜRETİMİ VE SORELMETAL ® İLE KIYASLANMASI<br />
Gökhan ÖZER a , Nilüfer EVCİMEN a , Ahmet EKERİM a *<br />
a Yıldız Teknik Üniversitesi Kimya-Metalürji Fakültesi Metalürji ve Malzeme Mühendisliği Bölümü 34210<br />
Esenler/İstanbul, Türkiye, E-posta: gozer@ yildiz.edu.tr, nevci@ yildiz.edu.tr, ekerim@ yildiz.edu.tr<br />
ABSTRACT<br />
Sorelmetal ® (high <strong>purity</strong> <strong>iron</strong> ingots produced <strong>by</strong> QIT - Fer<br />
et Titane Inc); is the most common charge material of<br />
ductile <strong>iron</strong> <strong>production</strong> used in worldwide range. In this<br />
study, high <strong>purity</strong> <strong>pig</strong> <strong>iron</strong>s with different compositions were<br />
produced from <strong>steel</strong> scrap instead of <strong>iron</strong> ore <strong>by</strong> <strong>using</strong><br />
electrical arc furnace. These products were compared with<br />
Sorelmetal ® , according to their chemical compositions and<br />
microstructure observation.<br />
Experimental studies were performed on <strong>pig</strong> <strong>iron</strong>s to<br />
examine the similarities to Sorelmetal ® . For chemical<br />
analyses optical emission spectrometry, for microstructural<br />
observation optical light microscope have been used. In<br />
addition, graphite sizes of the ductile <strong>iron</strong> were measured<br />
<strong>by</strong> <strong>using</strong> image analyzer.<br />
Depending on the obtained results, both structure and size<br />
distribution of graphites resemblances to Sorelmetal ® .<br />
Therefore this method can be used as a promising of<br />
Sorelmetal ®<br />
Key words: Pig <strong>iron</strong>, Sorelmetal ® , <strong>steel</strong> scrap, electrical<br />
arc furnace.<br />
ÖZET<br />
Sorelmetal ® (QIT – Fer et Titane Inc.’de tarafından üretilen<br />
yüksek saflıktaki demir ingotları); küresel grafitli dökme<br />
demir üretiminde dünya çapında en yaygın kullanım<br />
alanına sahip şarj malzemesidir. Bu çalışmada yüksek<br />
saflıktaki farklı kompozisyonlara sahip pik demir, demir<br />
cevheri yerine çelik hurda kullanılarak elektrik ark fırınında<br />
üretilmiştir. Üretilen pik demirler kimyasal kompozisyon ve<br />
mikro yapı incelemeleri bakımından Sorelmetal ® ’le<br />
kıyaslanmıştır.<br />
Deneysel çalışmalar, pik demirler ile Sorelmetal ®<br />
arasındaki benzerlikleri gözlemlemek amacıyla<br />
gerçekleştirilmiştir. Kimyasal analizler için, optik emisyon<br />
spektrometresi, mikro yapı incelemeleri için ise optik ışık<br />
mikroskobu kullanılmıştır. Buna ek olarak grafit boyutları<br />
imaj analiz cihazı kullanılarak tespit edilmiştir.<br />
Elde edilen sonuçlar doğrultusunda küresel grafitli dökme<br />
demirin hem yapısal hem de grafit boyut dağılımları<br />
Sorelmetal ® ’ e uyum sağlamaktadır. Buna bağlı olarak bu<br />
© IATS’09, <strong>Karabük</strong> Üniversitesi, <strong>Karabük</strong>, Türkiye<br />
metot Sorelmetal ® ’e alternatif olarak gelecek vadeden bir<br />
metottur.<br />
Anahtar Kelimeler: Pik demir, Sorelmetal ® , çelik hurdası,<br />
elektrik ark fırını.<br />
1. Introduction<br />
The first <strong>iron</strong> castings to be made were cast directly from<br />
the blast furnace. Foseco 23 Blast furnaces do not<br />
produce <strong>steel</strong>, they produce <strong>pig</strong> <strong>iron</strong>. Primary, Iron<br />
produced in the blast furnace is converted into the<br />
following commercial products as <strong>steel</strong>, cast <strong>iron</strong> and pure<br />
<strong>iron</strong>. Table 1.1. shows typical analysis of these products.<br />
[1]<br />
Table 1.1 Typical analysis of ferrous materials.<br />
Pig Cast White Cast Steel(%)<br />
Iron(%) Iron(%) Iron(%)<br />
C 3.5 – 4.25 2.5 – 3.75 1.75 – 2.7 0.10<br />
Si 1.25 0.5 – 3.0 0.8 – 1.2 0.02<br />
Mn 0.9 – 2.5 0.40 – 1.0 < 0.4 0.40<br />
S 0.04 0.01 – 0.18 0.07 -0.15 0.03<br />
P 0.06 – 3.0 0.12 – 1.1 < 0.02 0.03<br />
Liquid <strong>iron</strong> from a blast furnace contains around 4 %C and<br />
up to 2 %Si, together with other chemical elements derived<br />
from the ore and other constituents of the furnace charge.<br />
The presence of so much dissolved carbon etc. lowers the<br />
melt point of the <strong>iron</strong> from 1536°C (pure <strong>iron</strong>) to a eutectic<br />
temperature of about 1150°C (Fig. 1.1) so that blast<br />
furnace <strong>iron</strong> is fully liquid and highly fluid at temperatures<br />
around 1200°C.
Iron – Graphite ( - ) Iron- Carbide ( - - - )<br />
Carbon<br />
Content<br />
(%C)<br />
Temperature<br />
( °C)<br />
Carbon<br />
Content<br />
(% C)<br />
A 2.09 1154 2.12 1148<br />
B 4.25 1154 4.31 1148<br />
C - - 6.68 1226<br />
D 0.68 739 0.76 727<br />
Temperature<br />
( °C)<br />
Figure 1.1 The <strong>iron</strong>–carbon phase diagram. [2]<br />
While the solidification of the <strong>iron</strong>, most of the carbon is<br />
thrown out of solution in the form either of graphite or of<br />
<strong>iron</strong> carbide, depending on the composition of the <strong>iron</strong>, the<br />
rate of cooling from liquid to solid and the presence of<br />
nucleate. When the carbon is precipitated as flake<br />
graphite, the casting is called ‘grey <strong>iron</strong>’. (Fig. 1.2) if as<br />
carbide, the casting is said to be ‘white <strong>iron</strong>’. [3]<br />
Figure 1.2 Random flake graphite, X100. [4]<br />
Ductile <strong>iron</strong> has been known only since the late 1940s, but<br />
it has grown in relative importance and currently<br />
represents about 20 to 30% of the cast <strong>iron</strong> <strong>production</strong> of<br />
most industrial countries. [5] Ductile <strong>iron</strong>, also known as<br />
spheroidal graphite (s.g.) <strong>iron</strong> or nodular <strong>iron</strong> is made <strong>by</strong><br />
treating liquid <strong>iron</strong> of suitable composition with magnesium<br />
before casting. This promotes the precipitation of graphite<br />
in the form of discrete nodules instead of interconnected<br />
flakes (Fig. 1.3). The nodular <strong>iron</strong> so formed has high<br />
ductility, allowing castings to be used in critical applications<br />
such as: Crankshafts, steering knuckles, differential<br />
carriers, brake calipers, hubs, brackets, valves, water<br />
pipes, pipe fittings and many others. [3]<br />
Özer ,G., Evcimen, N. and Ekerim, A.<br />
Figure 1.3 Nodular graphite, X100. [4]<br />
The spheroidal form of graphite that characterizes ductile<br />
<strong>iron</strong> is usually produced <strong>by</strong> a magnesium content of about<br />
0.04 to 0.06%. Magnesium is a highly reactive element at<br />
molten <strong>iron</strong> temperatures, combining readily with oxygen<br />
and sulfur. For magnesium economy and metal<br />
cleanliness, the sulfur content of the <strong>iron</strong> to be treated<br />
should be low (preferably
Figure 1.4 Selective reduction of ilmenite. [6]<br />
The analysis of <strong>iron</strong> produced at Sorel also known as<br />
Sorelmetal® is given in Table 1.2. The slag is high in<br />
titanium and low in <strong>iron</strong> and is therefore preferable to<br />
ilmenite in manufacturing TiO2 <strong>pig</strong>ment or titanium metal.<br />
[6]<br />
Table 1.2 Analysis of <strong>iron</strong> produced from Qebec ilmenite at<br />
Sorel.<br />
C S P2O5 MnO<br />
1.8-2.5 0.11 0.025 Trace<br />
V2O5 Cr Si TiO2<br />
0 0.05 0.08 Trace<br />
As the primary sources of metal, natural ores deplete<br />
consistently, there is an obvious recognition that the total<br />
supply of any metal on Earth is finite. It is evident that the<br />
metals have to be recycled from "scrap" to maintain a<br />
steady supply to meet the demands of industry and<br />
wherever else metals are used., recycling of metal from<br />
secondary sources (scrap of relatively abundant metals<br />
like <strong>iron</strong>, <strong>steel</strong> and aluminum) is an established industry,<br />
motivated <strong>by</strong> both economic as well as env<strong>iron</strong>mental<br />
factors. [7] According to this approach, improvements on<br />
<strong>iron</strong>- <strong>steel</strong> industry in process steps are accelerated. [8]<br />
In this study, experiments were carried out <strong>by</strong> bringing a<br />
new, different point of view on high <strong>purity</strong> <strong>pig</strong> <strong>iron</strong><br />
<strong>production</strong>. An alternative method of <strong>production</strong> was<br />
investigated <strong>by</strong> <strong>using</strong> <strong>steel</strong> scrap instead of <strong>iron</strong> ore.<br />
2. EXPERIMENTAL METHODS<br />
Experimental studies started with selecting the<br />
conformable <strong>steel</strong> scrap. Chemical composition of the<br />
scrap was determined <strong>by</strong> optical emission spectroscopy on<br />
a HILGER Analytical.<br />
According to the determination of <strong>steel</strong> scraps, sawdust<br />
was prepared from them as small as possible in laboratory<br />
conditions. Graphite powders were used as a carbon<br />
source for transforming <strong>steel</strong> scrap to <strong>pig</strong> <strong>iron</strong>. Carbon<br />
Özer ,G., Evcimen, N. and Ekerim, A.<br />
tenor of graphite powder is % 99.5. Furthermore, pressing<br />
process was applied on both graphite powders and <strong>steel</strong><br />
scrap to obtain convenient samples for melting operations.<br />
Additional carbon content amount was determined <strong>by</strong><br />
<strong>using</strong> Equation 2.1 [9]<br />
A =<br />
( B − C ) xM<br />
G<br />
(Equation 2.1)<br />
A= Amount of charge C (kg) E=Percentage of<br />
experimental C (%)<br />
B= Percentage of exist C (%)<br />
G=Percentage of graphite<br />
tenor (%)<br />
M= Mass of <strong>steel</strong> scraps<br />
(kg)<br />
Melting process was realized on atmosphere controlled,<br />
single electrode, direct current electrical arc furnace as<br />
laboratory scale. Picture and schematic illustration of<br />
vacuum arc furnace has shown in Figure 2.1 a and b.<br />
(a) (b)<br />
Figure 2.1 Vacuum arc furnace (a) Picture (b) Schematic<br />
illustration [10]<br />
After melting process both chemical composition and<br />
metallographic analyses were done on prepared samples.<br />
The specimens were grinded and then polished with Al2O3<br />
paste. 2% nital was used to etch the samples. The<br />
microstructures of the samples were observed up to the<br />
magnification of 1000X in a light microscope with LEICA<br />
DFC280 Image Analyzer.<br />
3. RESULTS and DISCUSSION<br />
3.1. Chemical Analysis of Steel Scrap<br />
Acquirement of high <strong>purity</strong> <strong>pig</strong> <strong>iron</strong>, choosing the<br />
convenient <strong>steel</strong> scrap according to its chemical<br />
composition has great importance. The amount of Sulfur<br />
(S), Titanium (Ti), Magnesium (Mn) and Silicon (Si) must<br />
be as lower as possible. Chemical composition of selected<br />
<strong>steel</strong> scrap is shown in Table 3.1.
Table 3.1 Chemical composition of selected <strong>steel</strong> scrap.<br />
Fe C Si Mn P S Cr<br />
98.70 0.13 0.250 0.476 0.007 0.18 0.027<br />
As B Co Cu Nb Pb Sn<br />
0.006 0.00 0.004 0.040 0.006 0.00 0.024<br />
Mo Ni Ti V Al W<br />
0.00 0.02 0.00 0.00 0.052 0.04<br />
The results as shown in Table 3.1, suitability of selected<br />
<strong>steel</strong> scrap that would be used in experimental study.<br />
3.2. Determination of Charge Amount<br />
Mass of charge <strong>steel</strong> scrap was determinate as 20 g<br />
according to melting furnace conditions. Additionally,<br />
amount of charge carbon was measured <strong>by</strong> <strong>using</strong> Equation<br />
2.1. Percentage of exist carbon content was taken as 4.00<br />
and experimental was 0.134 (from Table 3.1). As<br />
mentioned before carbon tenor of graphite powder was<br />
taken as % 99.5.<br />
By placing, these dates in Equation 2.1, Equation 3.1 was<br />
achieved.<br />
( 4.<br />
00 − 0.<br />
134)<br />
× ( 20 g )<br />
( 99.<br />
5)<br />
A =<br />
≅ 0.<br />
780 g<br />
( 3.1)<br />
According to Equation 3.1 amount of charge carbon was<br />
determinate as 0.78g. After pressing the samples with<br />
pressing mold (Figure 3.1.(a)), shapes of samples became<br />
like Figure 3.1(b).<br />
(a) (b)<br />
Figure 3.1 View of (a) pressing mold, (b) pressed sample.<br />
3.3. Chemical Analysis of Samples<br />
Firstly, chemical analysis of Sorel <strong>pig</strong> was done as shown<br />
in Table 3.2.<br />
Table 3.2 Chemical analysis of Sorel <strong>pig</strong>.<br />
Fe C Mn S P Ni<br />
95.1 3.72 0.03 0.025 0.023 0.05<br />
Cr Cu Mo Al Sn As<br />
0.00 0.01 0.005 0.005 - -<br />
B V Nb Ti Si W<br />
- 0.05 0.007 0.003 0.032 0.00<br />
Chemical analysis results of five samples are given in<br />
Table 3.3, 3.4, 3.5, 3.6 and 3.7.<br />
Özer ,G., Evcimen, N. and Ekerim, A.<br />
Table 3.3 Chemical analysis of Sample 1.<br />
Fe C Mn S P Ni<br />
95.5 4.32 0.038 0.010 0.005 0.00<br />
Cr Cu Mo Al Sn As<br />
0.02 0.04 0.005 0.021 - -<br />
B V Nb Ti Si W<br />
- 0.00 0.006 0.003 0.007 0.013<br />
Table 3.4 Chemical analysis of Sample 2.<br />
Fe C Mn S P Ni<br />
95.5 4.09 0.146 0.031 0.007 0.00<br />
Cr Cu Mo Al Sn As<br />
0.00 0.00 0.002 0.025 - -<br />
B V Nb Ti Si W<br />
- 0.00 0.007 0.00 0.066 0.001<br />
Table 3.5 Chemical analysis of Sample 3.<br />
Fe C Mn S P Ni<br />
94.5 4.13 0.293 0.031 0.007 0.008<br />
Cr Cu Mo Al Sn As<br />
0.075 0.00 0.003 0.031 - -<br />
B V Nb Ti Si W<br />
- 0.00 0.010 0.00 0.22 0.099<br />
Table 3.6 Chemical analysis of Sample 4.<br />
Fe C Mn S P Ni<br />
95.4 4.18 0.054 0.028 0.08 0.00<br />
Cr Cu Mo Al Sn As<br />
0.00 0.025 0.002 0.054 - -<br />
B V Nb Ti Si W<br />
- 0.00 0.006 0.001 0.07 0.017<br />
Table 3.7 Chemical analysis of Sample 5.<br />
Fe C Mn S P Ni<br />
95.1 4.20 0.124 0.026 0.018 0.00<br />
Cr Cu Mo Al Sn As<br />
0.036 0.044 0.002 0.043 - -<br />
B V Nb Ti Si W<br />
- 0.00 0.015 0.00 0.331 0.048<br />
3.4. Microstructure Analysis<br />
Microstructure analyses with magnification of 100X are<br />
shown in Figure 3.2.
(a) (b)<br />
(c) (d)<br />
(e) (f)<br />
Figure 3.2 (a) Sorelmetal ® , (b) Sample 1, (c) Sample 2, (d)<br />
Sample 3 ,(e) Sample 4 ,(f) Sample 5 microstructures.<br />
The microstructures of the samples shown in Figure 3.2<br />
could be compared with sorel <strong>pig</strong> (Figure 3.2 (a)).<br />
However, structures were changed according to sample<br />
chemical compositions, they pointed similarities with<br />
Sorelmetal ® <strong>pig</strong> structure.<br />
4. CONCLUSION<br />
In this study, an alternative material, in comparison with<br />
sorel <strong>pig</strong> (most commonly used in <strong>production</strong> of spherical<br />
graphite cast <strong>iron</strong> known as ductile <strong>iron</strong>) has been<br />
investigated. During <strong>production</strong> process instead of <strong>using</strong><br />
<strong>iron</strong> ore, high quality <strong>steel</strong> scrap has been employed. <strong>High</strong><br />
quality <strong>pig</strong> <strong>iron</strong> <strong>production</strong> has been obtained <strong>by</strong> adding<br />
extra carbon into the <strong>steel</strong> scrap and melting in electrical<br />
arc furnace with repeating the operation three times.<br />
After melting process, completed similar results between<br />
samples and sorel <strong>pig</strong> were obtained in both chemical<br />
compositions and microstructures.<br />
According to this achievement, the <strong>pig</strong> <strong>iron</strong>s produced <strong>by</strong><br />
this alternative method could be used as an alternative of<br />
sorel metal <strong>pig</strong>.<br />
Furthermore, this method improves the recycling of <strong>steel</strong><br />
scrap that provides env<strong>iron</strong>mental and economical<br />
benefits.<br />
References<br />
Özer ,G., Evcimen, N. and Ekerim, A.<br />
[1] F. Habashi, Hanbook of extractive metallurgy, Vol.1,<br />
The Metal Industry Ferrous Metals, Wiley-VHC, 1997.<br />
[2] Elliott, R., Cast Iron Technology, Butterworth-<br />
Heinemann, reproduced <strong>by</strong> permission of the<br />
publishers, 1988.<br />
[3] J. R. Brown, Foseco Ferrous Foundryman’s Handbook,<br />
Butterworth Heinemann, 2000.<br />
[4] T. SJOGREN and I. L. SVENSSON, The Effect of<br />
Graphite Fraction and Morphology on the Plastic<br />
Deformation Behavior of Cast Irons ,Metallurgıcal And<br />
Materials Transactions A, Vol. 38A, 840-847, 2007<br />
[5] ASM Metal Handbooks, Vol.15, ASM International,<br />
1988.<br />
[6] www.sorelmetal.com<br />
[7] S. R. Rao, Resource Recovery and Recycling from<br />
Metallurgical Wastes, Elsevier, 2006.<br />
[8] M. Yanmaz, İklim Değişikliği ve AB Uyum Yaklaşımının<br />
Demir Çelik Sektörüne Etkileri, Erdemir Sürdürülebilir<br />
Çevre Grubu, Kasım 2005.<br />
[9] N. Aras, Küresel Grafitli Demir Dökümü, MMO, Yayın<br />
No:45, 1970.<br />
[10] A. C. Parlak, Titanyum Tetraklorürün Redüklenmesi ve<br />
Titanyum Üretim Koşullarının Termodinamik<br />
Esaslarının İncelenmesi, Y.T.Ü Metalurji ve Malzeme<br />
Müh. Bölümü Lisans Bitirme Tezi, İstanbul, 2004.