Metall. Res. Technol.

113, 401 (2016)


c EDP Sciences, 2016 Metallurgical Research
DOI: 10.1051/metal/2016016
&Technology
www.metallurgical-research.org

Comparison of different alternative steel

technologies: evaluation of case studies for
an innovative and sustainable steelwork
Valentina Colla1 , Renzo Valentini2, Barbara Fornai1
and Alessandro Amato1
1
Scuola Superiore Sant’Anna, TeCIP - PERCRO, Via Alamanni 13b, 56100 Ghezzano, San Giuliano
Terme, Pisa, Italy
e-mail: b.fornai@sssup.it
2
Università di Pisa, Dipartimento di Ingegneria Chimica, Chimica Industriale e Scienza dei Materiali,
Largo Lucio Lazzarino 2, 56126 Pisa, Italy

Key words: Abstract – In the international steel market, competitiveness is crucial since the market is
Steel making; smelting reduction; increasingly complex and dynamic. The steel companies face ever more stringent environ-
direct reduction; EAF; BF/BOF mental regulations pushing toward process improvements focused on increasing resource
efficiency while keeping economic sustainability. Investing in new and promising technolo-
gies when the current equipment and machinery become obsolete or unproductive is a task
of utmost importance although not always easy to achieve. In Italy a steelwork located in
Piombino produces high steel quality products but is currently undergoing an important
revamping and renovation process. The case of the Piombino steelwork is an interesting
example of the opportunities faced nowadays by European steel industry in the challenge
of increasing global competition. An overview of some combinations among the possible
and fruitful commercialized technologies that can be implemented in the specific situa-
tion and location of Piombino are presented and analysed. Each alternative technology is
Received 10 July 2015
briefly depicted as well as some economic and environmental aspects of the possible mix
Accepted 9 March 2016
combination.

last Furnace (BF)-Basic Oxygen Fur- it is at the end of its operative life and within

B nace (BOF) and Electric Arc Furnace

(EAF) are today the most common
routes to produce steel. In the BF-BOF pro-
a short term, it should be replaced or defi-
nitely shut down as well as the steel shop.
In Piombino’s steelwork there is also a coke
duction route, steel is produced from iron oven plant, but its full capacity is able to
ore while in the EAF steel is produced by cover only 50% of the BF needs and the nec-
the direct melting of steel scrap. According essary remaining coke has to be purchased
to [1], in 2013, in Italy, EAF steel produc- on the market. Its price volatility determined
tion accounted for 65.8% and BF-BOF steel by a limited stock unavoidably causes an in-
production for 34.2%. In Italy the most im- crease on the final steel production cost. In
portant integrated steel plants are located the past, in order to reduce coke consump-
as follows: one placed in Taranto which is tion, BF was retrofitted by upgrading a sys-
the biggest one for its size, one situated in tem of Pulverised Coal Injection (PCI) and a
Piombino and the last one located in Ser- sinter plant was also present too. In 1989 the
vola near Trieste. The steelwork located in sinter plant was closed since a necessary sub-
Piombino has an industrial port with one stantial revamping in accordance to the new
dock, one wharf, four cranes, two discharg- rules for environmental protection would
ers and a mooring capacity for ships up to have been necessary. In that period the iron
70 000 t of steel. It is equipped with a BF pellet price was very low but afterwards it
with a nominal capacity of 2.3 Mton/y of hot gradually increased due to a growing de-
metal, even if during the last years, BF steel mand in the market as many other sinter
production capacity was less than half since plants have been simultaneously closed in

Article published by EDP Sciences

 V. Colla et al.: Metall. Res. Technol. 113, 401 (2016)

Western Europe. The steelworks that instead in order to mantain the market share of high
have preserved the sinter plants thanks to quality products. According to [5], the pres-
investments in technological improvement sure to restructure and reduce production
acquired a great competitive advantage in capacity will remain one of the main chal-
the market. Moreover, if appropriate mate- lenges for the steelmaking industry in the
rial is used, sinter plants are in compliance foreseeable future. The creation of a center
with environmental regulation on air emis- in Lucchini spa for disposal of military ships
sions as demonstrated by several examples and handling of large cruise ships is another
in Europe [2]. In Lucchini spa, part of the pro- essential element in view of the reorganiza-
cess gases coming from the BF and coke oven tion planning of Piombino steelplant. The
plant is sold to the three power plants (one is recovered steel scrap from the ship disman-
currently being closed) producing an impor- tling can maintain a stable flow estimated
tant source of income. This is a benefit also approximately 100–200 kt per year. The steel
in terms of CO2 allowance saving as they scrap to be purchased on the market for
are considered as avoided emissions. In this some technical reasons can be imported by
article, an overview of the possible and reli- ship through the available port instead of
able steelmaking alternative technologies al- by truck and this can be considered as an
ready used at industrial scale which could be alternative and additional supply channel
implemented in Lucchini spa in place of the with respect to some Italian and European
current facilities will be presented and anal- steelworks.
ysed. In the literature, several studies can be Section 2 presents a general overview
found where different steelmaking technolo- of the ironmaking technologies that are al-
gies have been compared. Barella et al. [3] ternative to the traditional BF/BOF route.
have analyzed new innovative steelmaking Section 3 depicts some case studies, which
activities in order to increase competitive- will be analysed and compared from eco-
ness while complying with environmental nomic and environmental points of view. Fi-
regulations. Hasanbeigi et al. [4] describe nally, the main conclusions of the work are
and compare the most important emerging summarized in Section 4.
alternative technologies in terms of energy
and environmental benefits as well as infor- 1 Alternative ironmaking
mation on costs and commercialization sta- technologies
tus. The revamping of Lucchini is and must
remain fully consistent with the environ- 1.1 Direct reduction processes
mental regulation of the Integrated Pollution
Prevention and Control authorization duly There are several processes for direct re-
issued by the Environmental Minister [2]. At duction (DR) of iron ore which use coal or
the same time, Lucchini’s sustainable com- natural gas as fuel. Table 1 summarizes all
petitive position on the international and the most important commercial technolo-
global steel market should be preserved. gies for direct reduction as well as emerging
For such purposes, a technological restruc- technologies.
turation, which allows for a highly flexible The product of direct reduction is a
production with respect to the consumed spongy spheric iron pellet, called Cold Di-
raw materials ensuring the continuation of rect Reduced Iron (CDRI) or a solid ingot
high quality special steel production (i.e. for called Hot Briquetted Iron (HBI), which is
railway use) should be adopted. In such a denser than CDRI. CDRI worldwide pro-
way the considerable know-how achieved duction is about 8 times greater than the
through the years will not be lost, but rather HBI production, but HBI production covers
the economic sustainability and the future 45% of the traded market, due to less restric-
of such facility in the European steel mar- tive regulations for shipping [7]. DRI/HBI
ket will be guaranteed. The steel production is a flexible raw material because it can be
which is currently 1.6 Mt/year has to be re- charged hot in the EAF with significant en-
duced to approximately 1 Mt/year: this is the ergy saving or in the BOF as coolant sub-
minimum steel production level to be kept stituting steel scrap without affecting the
chemical quality of steel [3,8]. Natural gas as
401-page 2
 V. Colla et al.: Metall. Res. Technol. 113, 401 (2016)

Table 1. Direct reduction processes [6].

Principle Conventional processes Other processes

DR with natural gas, based Midrex NGTMr Danarex (merged in
on the shaft furnace HyLr (merged in ENERGIRON)
ENERGIRONr ) Ghaem (closed)
ENERGIRONr ULCORED (experimental
process)
DR with natural gas, based Finmet
on fluid bed principles Finex
Circored
DR based on coal Rotary Kiln Furnaces Grate Kiln
Rotating Hearth Fastmet
Furnace (RHF) Inmetco
Multiple Hearth Maumee
Furnace (MHF) Primus
Multi-Rotating Hearth Optimet
Furnace ITmk3
Higher temperature Circofer (closed)
Fluid bed Conjunct operation
Multi-Rotary Hearth with smelting reduction
Furnace (MRHF)
MXCOLr

reducing agent is used by MIDREX NGTM , of all forms of DRI products. It often consists
r r r
HyL /ENERGIRON and FINMET pro- of four stages: (1) reduction gas; (2) reform-
r

cesses. MIDREX Process Technology is ing; (3) heat recovery; and (4) briquette mak-
the world’s leading technology and cur- ing. DRI is produced by reacting iron oxide
rently it has evolved in two main configu- with a hot reducing gas containing mainly
rations: MIDREX NGTM (using natural gas) hydrogen (H2 ) and carbon monoxide (CO).
r
and MXCOL (using coal) [9]. MIDREX H2 and CO reduces Fe2 O3 into metallic iron
plants produce about 60% of the entire (Fe) and the by-products of this reaction are
r r
world’s DRI, HyL /Energiron accounts CO2 and H2 O [13, 14]. Iron oxide is reduced
r
for 15% and the remaining 25% accounts in the MIDREX Shaft Furnace by the re-
r
for the coal-based technologies [10, 11]. In ducing gas generated in the MIDREX Re-
r

order to achieve a better environmental former [9]. In the MIDREX Reformer natu-
performance, this analysis considers only ral gas is heated and catalytically reformed
the processes exploiting natural gas. Cir- along with recycled CO2 and H2 O from the
cored process uses pure hydrogen as re- reduction process to generate a rich reduc-
r
ductant and since hydrogen is not natu- ing gas to make DRI [13]. MIDREX Re-
rally available, it has to be obtained through former also provides the energy needed for
r
some processes consuming energy [12]. In the reduction reactions within the MIDREX
the case of Circored, the EAF melting has Shaft Furnace [13]. DRI yield can be up
to be adapted as there is no transfer of coal to 99%. Some MIDREX plant/EAF facilities
in the iron during the reduction. The Cir- emit only one-third of the CO2 per tonne of
cored process is not operating anymore and steel of a BF/BOF complex [15, 16]. The high
in the present analysis it will not be consid- simplicity using natural gas and agglomer-
ered. Finmet too is not widely spread: there ated iron ore and flexibility about iron ore
is only one plant in Venezuela [12] and, like reducing gas sources are the main benefits
Circored, it will not be included in this study. of this technology. Unfortunately, the need
to use a large amount of natural gas approx-
imately between 260–280 Nm3 /t DRI is the
1.1.1 MIDREX NGTM process main obstacle to its diffusion in the European
MIDREX NGTM , the natural gas-based con- Union [6]. An annual production of 500 kt
figuration of MIDREXr
process, is the most of DRI would require a supply of natural
widely-used technology for the production gas (with a calorific value of 8490 kcal/Nm3 )

401-page 3
 V. Colla et al.: Metall. Res. Technol. 113, 401 (2016)

between 130 and 140 million Nm3 /year. The ENERGIRON ZR. H2 O and CO2 are re-
only DRI-making plant in Europe is located moved through top gas scrubbing and CO2
in Germany near Hamburg and operates removal systems, respectively [22]. The CO2
since 1971. In 2013 DRI production was absorption system captures even the sulfur,
nearly 500 kt [17, 18]. According to [19], DRI whenever present in the process gas stream,
worldwide production increased from less reducing the overall SO2 emissions from
than one million tonnes per year in 1971 to the plant around 99% [24]. Some significant
over 70 million tonnes forty years later and achievements have been reached also in the
it is expected to continue this rapid increase reduction of NOx emissions. By adopting
for years to come. ultra-low NOx burners, the NOx emissions
can be reduced to values below 25 ppmv
(50 mg/Nm3 as NO2 ) [26]. Table 2 compares
1.1.2 ENERGIRON
R
process MYDREX r
and ENERGIRON r
ZR in terms
of facilities, type of feedstock, operating con-
r
ENERGIRON process uses a H2 -CO re- ditions and related flexibility [6].
r
ducing gas as in the MIDREX process. Midrex and HYL Energiron are the lead-
r r
ENERGIRON is the innovative HyL

di- ing technologies in shaft furnace direct re-
rect reduction technology developed jointly duction, and they account for about 76%
by Techint and Danieli, which merged of worldwide production [27]. They are the
their knowledge and previous technolo- most competitive ways to obtain high qual-
r
gies (Danarex and HyL ). Very recently ity direct reduced iron (DRI) for steelmaking.
r

ENERGIRON has introduced a reformer-
r
less version called ENERGIRON ZR (Zero
Reformer) [20] which uses a combination 1.1.3 ULCORED process
of partial oxidation of natural gas with
ULCORED is a breakthrough technology
oxygen and in situ reforming [10, 21].
r identified within the ULCOS consortium
ENERGIRON ZR provides a self (auto/in
and, like MIDREX and HyL, it produces di-
situ)-reforming of natural gas which directly
rect reduced iron from direct reduction of
occurs within the Vertical Shaft Furnace
iron ore (in form of lumps or pellets) by
(VSF) using DRI as catalyst. The reducing
gas-based direct reduction in a shaft fur-
gases are generated by “in-situ” reforming
nace [28]. An experimental direct reduction
within the reduction reactor, feeding nat-
pilot is planned to be erected in Lulea, but
ural gas as make up to the reducing gas
it is not yet confirmed [28–30]. This process
circuit and injecting oxygen at the inlet of
uses oxygen instead of air and the concept
the reactor [22]. Other reducing agents such
includes also a POX (partial oxidation) in-
as hydrogen gas, coal, pet-coke and similar
stead of reformers, shifter for production of
fossil fuel and coke oven gas, among oth-
CO2 free reduction/excess gas and the reduc-
ers, are also potential sources of reducing
ing agent being either natural gas or syn-
gas depending on the particular situation
gas from coal/biomass [31]. With respect to
and availability. HBI and DRI with a low r
MIDREX , it is able to reduce natural gas
or high carbon content are the main prod-
r consumption by 20–25% and CO2 emissions
ucts of ENERGIRON [23]. A high reduc-
by 15–20% [32]. There is also some signif-
tion temperature (above 1050 ◦ C), “in-situ”
icant savings in terms of electrical energy
reforming inside the shaft furnace and the
consumption [33, 34], even if its industrial
various energy recovery units in the plant
scale and feasibility are yet to be proved.
are the most important features in order
r This process needs to be supplied with iron
to optimize ENRGIRON ZR’s overall en-
ore of high quality [35].
ergy efficiency [24]. Therefore, DRI prod-
uct takes most of the energy supplied to
the process, with minimum energy losses 1.2 Smelting reduction processes
to the environment [25]. The selective re-
moval of both by-products, water and car- The Smelting Reduction (SR) process is an
bon dioxide, generated from the reduction alternative to BF route and to DRI produc-
process is one of the distinctive feature of tion. The final product is liquid pig iron or
401-page 4
 V. Colla et al.: Metall. Res. Technol. 113, 401 (2016)

r r
Table 2. Comparison between MIDREX and ENERGIRON ZR.

Operational parameters MIDREXr ENERGIRONr ZR

Type of reduction reactor Vertical Shaft Furnace Vertical Shaft Furnace
Reduction reactor size Bigger than HYL III and Smaller than MIDREXr
HYL IV with self-reforming (thanks to the lack of
the process gas channelling)
Iron oxide feedstock used Mix of iron ore, pellets and lumps Mix of iron ore, pellets and lumps
(# > 6.3 mm) (# > 3.2 mm)
Reducing gas generation CO2 -reforming. It does not need: Partial oxidation or “in- situ” gas
(1) Steam system reforming
(2) Reformed gas quenching CO2 emissions recovery from 60% to
Only 50% of CO2 recovery, 90% as by-product
in the reformer
Primary system of gas CH4 + CO2 ↔ 2CO + 2H2 CH4 +H2 O ↔ CO + 3H2
reforming reactions CH4 + (1/2)O2 → 2H2 O
2H2 + O2 → 2H2 O
2H2 + O2 → 2H2 O
CO + H2 O → CO2 + H2
Operational pressure 0.25 atm 8 atm
Reducing gas temperature 850–900 ◦ C 930–1000 ◦ C
Ability to process high It cannot be fed by high It can be fed by high
sulphur feedstocks sulfur content feedstocks. sulfur content feedstocks
Flexibility in operation Reduction and gas reforming Reduction and gas reforming
systems work as interrelated units. take place in the same reactor

in some cases, liquid steel [16]. It omits coke (2) a stage of gasification of coal and
production by combining the gasification of smelting reduction in the melter-gasifier,
r
non-coking coal with the reduction of iron which is the main reactor of the COREX
ore in a liquid bath [36]. SR includes several technology.
processes, some of which have been com- In the first step, lump iron ore and/or pel-
r
mercially proven e.g. COREX (where pel- lets and additives are loaded into the top of
lets and lump ores are reduced in a shaft), a reduction shaft. In the second stage, the
r
FINEX (where fines ore are reduced in a reduced iron is melted in a melter-gasifier
series of fluidized bed reactor) and ITmk3 unit using the energy generated from the
while others are still under development gasification (and partial combustion) of coal.
r
(e.g. Hismelt). However COREX , among Reducing gas (CO and H2 ) from the melter-
SR technologies, appears to be the most ma- gasifier is injected into the lower part to re-
ture one [4]. duce the iron ore to sponge iron. Hot metal
and slag are tapped at the bottom through
a similar procedure used in the BF conven-
1.2.1 COREX R
process
tional tapping [39]. The two stages allow to
r use a wide range of low cost coals (steam
COREX is a promising alternative emerg-
coal) directly (if the particle size is greater
ing ironmaking technology currently com-
than 8 mm) or in briquettes (if the parti-
mercially proven [37], even if there is a
cle size is less than 8 mm). As an alterna-
low adoption rate in the steel industry
tive to the coal, a 5% maximum amount
worldwide [4]. It allows for cost-efficient
of rigid plastics can also be fed directly
and environmental friendly production of r
into COREX . The process takes place at
hot metal directly from iron ore and non-
high pressure up to 5 bar and the reducing
coking coal [4,38]. SIEMENS VAI develops it.
r gas composition is 65–70% CO, 20–25% H2
COREX process is a two-stage direct smelt-
and 2–4% CO2 . The hot gas leaving from
ing processes:
the melter-gasifier unit is cooled to 800–
(1) a pre-reduction stage; 900 ◦ C and cleaned in a hot cyclone to recycle
401-page 5
 V. Colla et al.: Metall. Res. Technol. 113, 401 (2016)

r
entrained fines [40]. COREX export gas can lump form and the rest (35%) is fed as pul-
be utilized in several ways: verized coal along with oxygen in the lower
part of the melter-gasifier. The conversion of
(a) directly within the cycle;
coal into char and its gasification is similar
(b) DRI production; r
to the COREX processs [44]. The hot DRI is
(c) electric energy generation;
compacted and charged into a melter gasi-
(d) heating;
fier unit [45].
(e) steam production;
(f) chemical processes [41]. HIsarna (“HI” from HIsmelt and “sarna”
r
from the Celtic for iron isarna) is one of
COREX uses approximately one tonne of the different processing methods selected
coal per tonne of hot metal with approxi- within the ULCOS project [28, 29, 46]. The
mately 45% of the total energy input used HIsarna process produces liquid hot metal
in ironmaking while the rest goes to the ex- from iron ore fines using non-coking coal as
port fuel gas [42]. The produced hot metal reductant. There is no need for ore agglom-
has carbon and silicon content similar to BF eration or coking. It is a two-step process: a
hot metal, while the sulfur content is much cyclone where the fine ore is prereduced and
higher [40,42]. The coal particle size used by melted and an iron bath reactor where the
r
COREX is moderately higher than BF, gen- ore is finally reduced. The reactor uses the
erating a 30–35% of discard with respect to heat generated by degassing the coal [47].
the standard coal supply. There is a negative It requires considerably less carbon than a
impact on the production costs if the inter- conventional BF with a significant CO2 emis-
nal re-use or the selling of this coal is not sions reduction. It is also a flexible process
possible [43]. A comparison between a con- allowing a partial substitution of coal by
r
ventional BF and a COREX process shows biomass, natural gas or hydrogen [32]. A
r

that COREX uses more additives and more HIsarna pilot plant with a nominal capacity
oxygen (from 12 to 24 times more) and it of 60 000 t/year (8 t/h) is located in the Tata
consumes more nitrogen (3.6 times more). It Steel site of Ijmuiden (The Netherlands) [32].
consumes less iron ore (–6%) and less electri- This pilot plant has been constructed by a
cal energy (–11%) than the BF/BOF route. As Consortium of European steelmakers united
r
far as the process gas is concerned, COREX in the ULCOS project with the support of Rio
generates the same amount as the BF, but Tinto [48].
with a higher calorific value (approximately
2.2 times). With regard to CO2 emissions, a The REDSMELTTM process can treat
total reduction is generated, as some plants most iron-bearing materials such as iron ore
i.e. the sinter plant and coke oven plant are fines, iron and steel mill solid and liquid
missing. wastes to produce hot metal [49]. It cou-
ples a Rotary Hearth Furnace (RHF) and
an EAF smelter to convert recycle iron ore
1.2.2 FINEX, HIsarna and REDSMELT fines into hot metal or alloys and slag. Re-
duction takes place in a RHF which can
r r
Like the COREX process, FINEX is a two- use a variety of carbon-containing materi-
stages melting reduction method of iron- als such as anthracite, pet coke and ground
making. It is based on direct use of non- electrodes as reductant to produce DRI for
coking coal and fine ore and with respect recycling or smelting in a submerged arc fur-
r
to COREX it can directly use iron ore sin- nace. This technology has been developed
ter feed (up to 0.012 m) without agglomera- to meet a growing demand of low-cost and
tion [4]. A series of successive fluidised bed environment-friendly production process of
pre-reduction reactors in which ore fines are hot metal due to its low emission levels, but
reduced in three or four stages to DRI and a it has not yet reached the necessary consoli-
melter-gasifier are the main units of this iron- dation of its economic viability [50, 51]. Cur-
making system. The iron ore passes through rently this process has a range of production
4 reactors where it is heated and reduced by of 0.3–1.0 Mt/year of hot metal and may be
a reduction gas also produced by coal gasifi- used to treat a wide range of fine iron ores
cation. The major part of coal (65%) is fed in and steelmaking residues [52].
401-page 6
 V. Colla et al.: Metall. Res. Technol. 113, 401 (2016)

2 Evaluated case studies costs since the building of facilities nec-

essary to supply a large amount of natu-
In this study, several different routes have ral gas is avoided. Apart from MIDREX r
,
been identified and analysed in order to de- the gas can be used also as a fuel for feed-
fine the best solution for the particular situ- ing a power plant. Thanks to a simple
ation in Piombino: mass balance (even taking into account
(1) Benchmark route (BF/BOF): in this partic- the non-unitary yield of the process), it
ular scenario, a new BF-BOF route with a is obvious that such type of process sys-
production of 1 Mt of hot metal per year tem leads to an excess of steel produc-
to be converted into 900 kt of high qual- tion with respect to the target (1 Mt/year
ity crude steel is supposed to be erected. of liquid steel). However, SR facility is
A new sinter plant with a production ca- not economically convenient below the
pacity of around 1 Mt of sinter per year size indicated above and the size of the
has been assumed to be built too. The DR plant is determined accordingly. The
ship dismantling would be able to sup- target of steel production could be main-
ply about 100 kt of steel scrap. The cur- tained if part of the DRI produced and
rent coke plant is still quite modern and hot metal is sold. In this scenario, an es-
it can be exploited without any refur- timated balanced proportion among the
bishment causing a reduction of 25% on three main important components com-
the investment cost with respect to a full poses the EAF charge: 33.5% steel scrap,
greenfield [12]. 35% hot metal and 31.5% DRI. A pro-
(2) Scrap-EAF route (50% EAF): this route duction surplus of about 130 kt of hot
includes the installation of an EAF able metal and DRI will generate an addi-
to produce 1 Mt of high or low qual- tional source of revenue.
ity crude steel per year according to the
needs. 500 kt steel scrap and 500 kt of As far as the process flexibility is concerned
granulated hot metal or purchased DRI with respect to the steel production volume,
feed the EAF. a fundamental difference can be highlighted
(3) Smelting Reduction+EAF route between the benchmark case and the other
(SR+EAF): this option considers the scenarios. Even if for short periods the BF
installation of an EAF producing can be stopped, it has to be maintained in an
1 Mt/year of steel, which is fed by 500 kt operative way in order to avoid a permanent
of steel scrap and 500 kt of hot metal shut down causing high costs of revamping.
produced with a SR process, for instance During serious crisis periods, there are some
r
the COREX process. examples of BFs with a production between
(4) Direct Reduction+EAF route (DR+EAF): 50% and 80% of their effective production
this route takes into consideration the capacity causing a reduction of the produc-
installation of an EAF, which produces tion process efficiency and an increase of the
1 Mt/year of steel. EAF is charged with specific production cost. The EAF procedure
500 kt of steel scrap and 500 kt of DRI pro- to switch on and off the system is also faster
duced with a direct reduction process, for and cheaper and steel production is directly
r
instance the MIDREX process. proportional to steel scrap and energy input.
(5) Smelting Reduction + Direct Reduction As far as the flexibility of the process is con-
+ EAF route (SR + DR + EAF): this cerned with respect to raw materials prices
last option considers an EAF producing and product quality, a more accurate and ef-
1 Mt/year of steel. This EAF is fed by ficient control on the production cost can
335 kt of steel scrap, 500 kt of hot metal be monitored on EAF process with respect
produced with a SR process for instance to BF/BOF since the % EAF mix charge can
r
COREX and 450 kt of CDRI produced be varied between hot metal and steel scrap
with a direct reduction process, for in- according to their quotation on the market.
r
stance MIDREX . In this scenario, the The high difficulty to adapt the productive
r r
MIDREX process is fed by COREX

gas requests to the raw materials prices and to
instead of natural gas. It causes a reduc- the quality product demands is one of the
tion on the investment and production main reason for the steelmaking industrial
401-page 7
 V. Colla et al.: Metall. Res. Technol. 113, 401 (2016)

crisis. Such economic crisis has then led to stall more plants can negotiate the invest-
a marked downturn in steel manufacturing ment cost. The analysis of very specific situ-
and to an associated steel demand which re- ations deriving e.g. from particular commer-
mains 27% below pre-crisis levels [5]. cial framework agreements requires ad-hoc
data and information and is thus out of the
scope of the present paper.
2.1 Economic analysis

Decision making on investment alternatives 2.1.1 CAPEX

is often carried out based on economic and
environmental considerations. Such consid- The CAPEX estimation of a project is of ma-
erations are even more difficult due to the jor importance for a significant and reliable
fact there are not many data and informa- economic feasibility study. In this study, both
tion available on the alternative ironmaking direct and smelting reduction investment
technologies. Assumptions and hypothesis cost has been estimated based on similar
have been extrapolated from literature data: equipment costs according to the method-
any adjustment on the input data can affect ologies adopted in references [12]. Refer-
the results. The economic analysis has been ence [55] has been used as reference for the
carried out by estimating Capital Expendi- estimation of a sinter plant to be built ex-
ture (CAPEX) and Operational Expenditure novo producing about 1 Mt/year of sinter in
(OPEX) as well as a profitability indicator the benchmarking scenario. The remaining
called ROI for each above depicted scenario facilities have been estimated according to
in order to carry out a sensitivity analysis two options:
in terms of an important economic indicator
(a) 1st option (brownfield): the EAF is placed
called Payback Period (PBP), which is often
in the current hot metal area. The es-
used in evaluation of different investment al-
timated CAPEX and installation time
ternatives. PBP is the period of time required
are of about 60 Mc and 10 months,
for a product or a project to pay for itself [53].
respectively;
Two common methods are commonly used:
(b) 2nd option (greenfield): the EAF and con-
Simple PBP, which is calculated as the ra-
sequently rolling mills for wire rods and
tio between the investment amount and the
rails as well as continuous casting are de-
operating profit, and Actualised PBP which
localised into a different area (with an es-
is more accurate as it takes into consider-
timated CAPEX of about 300 Mc with
ation the discounted cash flows generated
an installation time of approximately
from the investment [54]. Data related to
3 years). In this case, the hot metal area
smelting and direct reduction technologies
as well as all the other facilities neces-
industrially and commercially proven have
r sary for the normal operating conditions
been used. In particular, MIDREX process
r to produce steel have to be built ex-novo.
data for DR and COREX data of Siemens
This necessarily causes an increase of the
VAI for SR have been exploited. The CAPEX
total equipment to be purchased.
and OPEX reference data used for the anal-
ysis are the basis for the extrapolation of The 2nd option is relevant since currently
some estimates, but the data obtained in the hot metal area in Lucchini spa is close
this study cannot be considered as exact fig- to the living area, but it is quite far from
ures of the plant cost. Reference data, which the continuous casting involving some lo-
should be rigourous and consolidated, are gistical and handling problems. Such option
necessary in order to obtain reliable and sig- enables to place all the facilities within the
nificant results. However, these data are con- same area causing a more efficient and well-
tinuously changing, as they are related not organized raw material and finished prod-
only to technological progress which can re- ucts management. For a maximum produc-
duce the investment cost when a new tech- tivity and synchronization of production,
nology becomes a proven commercial plant, the logistic and scheduling should be de-
but also relative to the needs of the investor: signed in order to not to limit the end-to-end
for instance an investor which decides to in- production and also the delays/stoppages
401-page 8
 V. Colla et al.: Metall. Res. Technol. 113, 401 (2016)

Table 3. CAPEX expressed in Mc. and reduction technologies. All the calcula-
CAPEX Mc tion have been carried out considering as the
BF+BOF 295 final output a ton of liquid steel. In particu-
Sinter plant 40 lar, in order to have an idea of the unitary
SR process 132 cost of each scenario, the cost analysis has
DR process 92 been carried out estimating the consumed
Brownfield Greenfield raw materials, energy consumption as well
EAF scenarios 60 300
as labor cost. The EAF main raw materials
and consumed energy taken into consider-
should be minimized [56]. According to the ation are electrical energy, oxygen, fluxes,
above assumptions and hypothesis, Table 3 graphite and refractories. In the direct re-
shows the estimated CAPEX for the consid- duction technology, the amount of iron ore
ered technologies. is estimated as 1.42 t/t DRI. Natural gas, air
The above estimated CAPEX for each compressed and water have been estimated
technology have then been merged in order too. In the smelting reduction technology,
to find the CAPEX of each above depicted the estimated coal consumption is 1.30 t/t
scenario. Figure 1 shows the total CAPEX hot metal, while estimates for iron ore and
for the five production scenarios. The over- additives are 1.51 t/t hot metal and 0.24 t/t hot
all implementation of the Greenfield 5th sce- metal, respectively. Other elements, i.e. oxy-
nario has the highest CAPEX with 524 Mc gen, water, nitrogen, air compressed have
whereas the lowest one is observed at the been taken into account. As far as the unit
brownfield 2nd scenarios with 60 Mc. EAF prices values are concerned, raw materials
greenfield requires more CAPEX than EAF and energy have been estimated according
brownfield scenarios since all the necessary to [32,57]. In the estimation of labor cost, the
equipment and facilities for the steel produc- workers in all five scenarios are subdivided
tion have to be acquired. BF/BOF requires as follows: 69% workers, 30% employees and
less CAPEX with respect to the EAF Green- 1% managers. The following average hourly
field scenarios due to the fact that CAPEX in- costs for each category have been consid-
cludes a new BF/BOF plant and a new sinter ered: 20 c/h for workers, 35 c/h for employ-
plant, but it does not take into consideration ees and 55 c/h for managers. An EAF steel
a coke plant and the rest of the necessary scrap load of about 1.1 k/t LS [2] has been
equipment since they are in a good working considered, in accordance to the BREFs, and
condition. Nevertheless BF/BOF CAPEX is its composition on all scenarios is as follows:
higher than EAF Brownfield scenarios. The (i) 70% shredded steel scrap (E40 Cate-
Brownfield 2nd scenario seems the most fea- gory);
sible from a CAPEX point of view: this is (ii) 30% steel scrap coming from ships dis-
clearly due to the fact that only the EAF has mantling.
to be built but in a long term vision such sce-
In case of the steel scrap coming from
nario is strictly connected to the DRI prices
ships dismantiling, a reduction of 20% on
and its variations in the market.
the scrap prices with respect to the shred-
ded scrap prices has been assumed. Table 4
2.1.2 OPEX summarizes the details of hypothesis and
assumptions taken into consideration for
After an estimation of the CAPEX of each OPEX calculation. In both “SR+EAF” and
scenario, a simple preliminary cost analysis “SR+DR+EAF” scenarios a power reduction
for all five scenarios has been performed by as well as a reduction on the refractory and
estimating OPEX. Each scenario was based graphite consumption have been assumed
on a plant capacity of 1 Mt/year of liquid due to the fact that hot metal is charged.
steel and operating working hours were as- According to the above assumptions, the
sumed to be 2080 h/y. In EAF scenarios, the breakdown of OPEX for each scenario is
OPEX calculation has been carried out con- shown in Figure 2.
sidering the main component of EAF cou- There is a significant increase in OPEX
pled with the main factors of the smelting of BF/BOF scenario with respect to EAF
401-page 9
 V. Colla et al.: Metall. Res. Technol. 113, 401 (2016)

Fig. 1. A comparison of Capital Expenditures for the alternative steelmaking technologies.

Table 4. Assumptions for each depicted scenario.

Scenarios EAF Load Mix Composition Economic Assumptions and

Hypothesis
BF/BOF – A sinter plant has to be
installed.
“50% EAF” [2] – 50% Purchased DRI –
(0.51 t/t LS)
– 50% Steel Scrap
(0.56 t/t LS)
“SR+EAF” [58, 59] – 50% Steel Scrap (0.56 t/t LS) – 55% Reduction of power
– 50% Hot Metal product consumption;
(0.52 t/t LS) – 15% Increase of oxygen;
– 30% Reduction of graphite
consumption;
– 40% Reduction of refrac-
tory consumption;
– hot metal yield estimated at
96%;
– sales of discarded coal (30%
less than the purchasing cost)
– recovery of COREXr gas
valued at 52.5 c/t
Hot metal yield estimated at
96%
“DR+EAF” [15, 60, 61] – 50% Steel Scrap (0.56 t/t LS) DRI yield estimated at 99%
– 50% DRI product (0.51 t/t
LS)
“SR+DR+EAF” [15, 58–61] – 33.5% Steel Scrap (0.37 t/t – 33% Reduction of power
LS) consumption;
– 35% Hot Metal product – 23% Reduction of graphite
(0.36 t/t LS) consumption;
– 31.5% DRI product (0.32 t/t – 23% Reduction of refrac-
LS) tory consumption;
– 16% Increase of oxygen.
– other assumptions are the
same as for “SR+EAF” and
“DR+EAF” scenarios

401-page 10
 V. Colla et al.: Metall. Res. Technol. 113, 401 (2016)

Fig. 2. Breakdown of OPEX in c/t LS.

scenarios: about 40% more with respect to adopted technology and the annual produc-
“SR+DR+EAF” scenario. According to the tion costs. The obtained values are shown in
Figure 2, the scenarios associated to an EAF Table 5.
are the most convenient. In “50% EAF” sce- The Greenfield scenarios obtain lower
nario the main cost component is the pur- values with respect to the Brownfield scenar-
chasing of DRI (about 40%): the DRI price ios: this is due as the CAPEX of Greenfield
has been retrieved in reference [62] and, ob- scenarios is higher than the brownfield
viously, if different prices are used, OPEX ones causing a reduction on the values.
result will change. In the scenarios where In the Greenfield scenario, the combination
smelting reduction is implemented, an im- of smelting and reduction technologies ob-
portant assumption is the sales of the dis- tains a better value than the “DR+EAF” and
carded coal. In fact such sales and the recov- “SR+EAF” ones since the plant obtains addi-
r
ery of COREX gas in place of natural gas tional revenues from the selling of hot metal
reduce OPEX about 4% in “SR+EAF” and and DRI surplus.
8% in “SR+DR+EAF” with respect to “50%
EAF”. From an economic point of view, it
seems that “SR+DR+EAF” is the most con- 2.1.3 Sensitivity analysis
venient due to the combination of savings
of smelting and direct reduction technology. In this section, the effect of influence of vari-
However, a complete economic estimation ous parameters on the convenience to invest
of OPEX and CAPEX depends on many in some scenarios is discussed. In the first
factors which may also change from loca- sensitivity analysis, which compares “50%
tion to location as, for instance, energy and EAF” vs. “SR+EAF” scenario, the effects that
raw materials prices [38]. A profitability in- the fluctuations of DRI/hot metal prices in
dicator called Return On Investment (ROI) “50%EAF” scenario have on the convenience
which is the percentage of the money re- to invest in “SR+EAF” scenario in terms of
covered annually from the plant (ROI% = payback period are investigated. DRI and
Profit/CAPEX) has also been estimated ac- hot metal prices varied in a limit range in
cording to the above assessed CAPEX and order to understand when it becomes more
OPEX. The annual profit has been computed profitable to purchase DRI or hot metal in the
as the difference between a rough estimation market than to produce them. The cost re-
of the annual revenues produced from the lated to DRI or hot metal purchasing would
401-page 11
 V. Colla et al.: Metall. Res. Technol. 113, 401 (2016)

Table 5. ROI Indicators of the five scenarios.

Brownfield Greenfield
Scenarios Scenarios
BF/BOF 50%EAF DR+EAF SR+EAF SR+DR+EAF 50%EAF DR+EAF SR+EAF SR+DR+EAF
ROI 7% 42% 12% 11% 12% 8% 5% 5% 6%

be saved if “SR+EAF” scenario would be projects [63]. The results of Simple and Ac-
implemented, but the convenience to invest tualised PBP are shown in Figures 3a and 3b.
in “50%EAF” scenario is strictly related to According to the above assumptions,
DRI/hot metal market price. According to Figures 3a and 3b demonstrate that the
the approach adopted for OPEX calculation, higher the hot metal or DRI price, the shorter
the following additional assumptions have the time to recover the “SR+EAF” invest-
been made: ment as more savings would be cumulated
through the years. If the DRI market price
– source of Financing: 100% Equity is higher than 370 c/t the Actualised PBP to
Capital; recover the “SR+EAF” investment would be
– investment depreciation (years): 20; lower than 10 years as shown in Figure 3a.
– DRI to be purchased (kt/year): 510; When the variations are applied to the hot
– hot Metal to be purchased (kt/year): 510; metal prices, PBP is more sensible as it can
– DRI market basic price (c/t): 291 [15]; be seen from Figure 3b: in order to get a
– hot metal market basic price (c/t): short actualised PBP (i.e. less than 10 years),
358 [15]; the hot metal market price should exceed c
– interest rate: 4%; 370/t, which is not very far from the current
– hot metal cost estimation (c/t): 328; market price according to [15]. However,
– DRI cost estimation (c/t): 273; in terms of profitability, the “SR+EAF” sce-
– steel production (Mt/year): 1; nario becomes profitable and cost-effective
– surplus hot metal to sell (kt/year): 135; when simple or actualised PBP is shorter
– surplus DRI to sell (kt/year): 131; than 5 years. The second sensitivity analysis
– taxes: 40%. considers the “50% EAF” vs. “DR+SR+EAF”
scenarios. In this case, not only DRI and hot
Mortgage and financial charges are not in- metal savings, but also the selling of DRI
cluded as the capital equity is supposed and hot metal surplus not used in EAF (as-
to finance all the investment amount. The suming that the steel production is fixed to 1
discounted cash flows have been estimated Mt) have been considered. In this case, DRI
starting from the net operating result (differ- and hot metal prices variations have been
ence between revenues and operating costs, combined among them in order to deter-
but after the taxes) and considering the de- mine the trend of the actualised PBP of the
preciation as a positive variation. In this “DR+SR+EAF” scenario (Fig. 4). Not only
analysis, the taxes were set at 40% which can DRI and hot metal prices variations af-
is an average value representing the Italian fect the PBP, but also the amount of invest-
tax system, but it can change according to ment: for instance, if a 20% reduction is ap-
the value adopted in the considered coun- plied on CAPEX of both Smelting and Direct
try. Obviously the lower the tax value the Reduction process, PBP results decrease fur-
higher the net operating result. The cash ther as shown in the Figure 4b. Any variation
flows are discounted with an interest rate in the input data as well as in the estimated
of 4% according to the Net Present Value assumptions can affect the final results of the
(NPV) method. The interest rate, in such analysis and obviously the results of PBP.
cases, usually corresponds to the Minimum All the above assumptions, especially the
Acceptable Rate of Return (MARR), i.e. the decisions on how to finance CAPEX (debt or
minimum rate of return on a project that equity capital) are an important weight on
a manager or company are willing to ac- the final results obtained as they affect the
cept before starting a project, given its risk investment recovery time and therefore the
and the opportunity cost of forgoing other simple or actualised PBP duration.
401-page 12
 V. Colla et al.: Metall. Res. Technol. 113, 401 (2016)

Fig. 3. Sensitivity Analysis in terms of Simple and Actualised PBP: sensitivity with respect to DRI prices (a) and
sensitivity with respect to hot metal prices (b).

Fig. 4. Actualised PBP Results: CAPEX without any reduction (a) and CAPEX with a reduction of 20% (b).

2.2 Environmental issues trated the conditions under which it would

be beneficiary as well as the implications of
In a full integrated steel production cycle the integration on the overall CO2 emissions
with a coke oven plant and a sinter plant, of the plant [68]. The integrated steelplant
environmental issues become severe due to involves the production of a considerable
the fact that steel industry is highly inten- amount of by-products and wastes, the dis-
sive in both materials and energy. Accord- posal of which has been always carried out
ing to [64], the energy intensity of steelmak- in Piombino in compliance with national and
ing was 19.6 GJ per ton of steel cast and the European regulation even if it implies sig-
amount of CO2 emissions was 1.7 ton of CO2 nificant costs. However, the steelmaking in-
per ton of steel cast in 2012. The iron and steel dustries should also improve recycling as
sector is in fact the second-largest industrial much as possible to prevent and to minimize
user of energy after the chemical and petro- waste production and reusing, recycling and
chemical sector. recovering should be the priority in order to
Previous studies and useful indicators improve environmental sustainability [69].
have been identified in order to quantify pro- In reference [70] several activities described
cess parameters and determine the efficiency by the generic word “recycling” in the steel
and the environmental impact of the iron industry with an evaluation of the benefits in
and steel production process [65–67]. Huitu terms of natural resources or energy savings
et al. studied the potential of using direct re- are presented. The replacement of the cur-
duced iron from the Midrex process, based rent integrated steelmaking route with alter-
on shaft furnace technology, as a partial sub- native technologies could lead to significant
stitute for pellets in a blast furnace and illus- benefits in the overall environmental perfor-
401-page 13
 V. Colla et al.: Metall. Res. Technol. 113, 401 (2016)

mance with respect to the current situation. of natural products such as vegetable oil and
A particular importance should be given to animal fats. The iso-butilene is very impor-
atmospheric emissions, especially the ones tant in the petrochecmical sector for the pro-
related to greenhouse gases (GHG Gas), due duction of fuels, plastics materials, organic
to the ambitious targets set in Europe (–20% glass and elastomers. Lanzatech process is
by 2020 and –87% in 2050 compared with already applied in the steel industry claim-
1990) [71]. However, other types of emis- ing that CO2 emissions are reduced by one
sions, e.g. particulate matter and dioxins, are third with respect to using the process gases
r
extremely important, especially considering as fuel [73]. LanzaTech company claims
the impact at local level and the potential ef- that globally up to 150 million tonnes of CO2
fects on the workers’ health as well as on the emissions could potentially be avoided by
community living in the surroundings of the re-using available steel mill gas residues us-
steelmaking plant. ing LanzaTech’s process [74].

2.2.1 Process gas exploitation

2.2.2 Energy and infrastructure issues
for the production of bio-ethanol
The gas produced by a SR process, such as The implementation of the above depicted
r
for instance COREX process, is a stable gas steelmaking production routes should con-
with a high calorific value and some signif- sider the availability of a suitable electrical
icant properties: it is rich in carbon, in CO, energy network. The environmental impact
in hydrogen and, in particular, in CO2 in a related to the power plant conversion should
measure of 30–35%. This gas could be used be taken into consideration for a sustainabil-
in a novel process developed by a company ity analysis. Currently, in Piombino, there
r
named LanzaTech . Such company com- are three power plants (one actually close to
mercializes a pioneering carbon capture and disposal) fed by the process gas produced by
reuse technology that converts carbon-rich the integrated steelmaking route. If in the fu-
waste gases (containing CO, CO2 and hy- ture such export process gas production de-
drogen) into high-quality, advanced biofu- creases or is even missing, other fuels for the
els and chemicals [72]. Through production power plants will be needed to replace them,
r
of chemicals, LanzaTech presents a route as Piombino steelwork should continue to
whereby carbon in waste gases and residues rely on a functional power plant.
is sequestred into a new product. Such Such power plants should be sized ac-
process uses microbes consuming the gas cording to the needs of the chosen steelmak-
and producing ethanol as a byproduct. The ing route, but also to the eventual require-
carbon-rich waste or residue gas streams en- ments of the adjacent industrial area. At
ter a fermentation bioreactor. Valuable prod- the same time, the power plant should con-
ucts are then separated from the fermenta- tinue to re-use process gas even produced
tion broth and used directly downstream or by smelting and/or direct reduction. In order
as chemical intermediates for products such to implement all EAF-based scenarios above
as plastics, nylons, rubbers, and "drop-in" depicted, some infrastructural measures will
fuels. The produced bio-ethanol can be used be nevertheless needed in order to adapt
as a fuel. The butadiene has a wide-range the electrical network to the EAF needs. In
of applications in the production of styrene- the 3rd scenario, for instance, a power plant
butadiene rubber, which is a key ingredient could be specifically sized ad-hoc to provide
for the tire industry worldwide and as a raw electrical energy for the oxygen plant, since
material for nylon production. The acetic it is used in large quantities by the SR pro-
acid is used in the textile, adhesives, solvents cess and due to the fact that almost 70% of
and coatings industry. The iso-propanol is the operating costs accounts for electrical en-
an important industrial solvent, with appli- ergy consumption. Furthermore, in case SR
r
cations in the field of cosmetics and personal is implemented through the COREX pro-
care products, antifreeze, paints and resins, cess, one of the power plants could be re-
pharmaceuticals, foods, inks and adhesives. vamped and converted to a new fine coal-
It is used in the extraction and purification fired power station. The ash produced by the
401-page 14
 V. Colla et al.: Metall. Res. Technol. 113, 401 (2016)

Table 6. Comparison of 5 scenarios.

BF/BOF 50% Scrap-EAF SR+EAF DR+EAF SR+DR+EAF

(1th scenario) (2nd scenario) (3rd scenario) (4th scenario) (5th scenario)
kg CO2 /tLS 1888 455 1,220 828 931
(% wrt BF/BOF) (–76%) (–35%) (–56%) (–51%)
Dust from raw – –100% –92% –72% –89%
materials stocking area
PCCD/PCFD – –65% –99% –72% –84%
SO2 – –56% –96% –95% –86%
NOx – –33% –87% –92% –75%
OPEX c/tLs 475 375 359 362 346
(% wrt BF/BOF) (–21%) (–25%) (–24%) (–27%)
132+EAF 92+EAF 92+132+EAF
Investment cost 335 60 300
(for the plant) [295 (BF/BOF (No (De-loc.
Mc +facilities) de-loc. EAF)
3+40 (sinter)] EAF)
192 432 152 392 344 524
(No de-loc (De-loc. (No de-loc. (De-loc. (No de-loc. (De-loc.
EAF.) EAF.) EAF) EAF) EAF) EAF)
Required None Import of Conversion of Connection with Conversion of
facilities electrical power one power pipeline from one power
Conversion of plant to fine coal Elba LNG plant to
power plant: Terminal of fine coal
– Natural gas Livorno
(pipeline)
– Fine coal

power plant could be completely collected in order to implement new measures to in-
and used for the preparation of conglom- crease the energy efficiency and the reduc-
erates by a local company which is already tion of specific consumptions. In the 4th sce-
a partner of Piombino steelwork for wastes nario it is necessary to consider not only the
and by-products management. Moreover, a time and costs related to the implementation
portion of the electrical energy produced but also the construction and the impact of
could be sold in an internal network system the external related infrastructures to sup-
to several companies located in the vicinity ply and guarantee a large amount of natural
of the Piombino industrial area possibly at gas. It is important to point out that in an
favourable conditions, with a considerable Italian scenario the natural gas has a high-
competitive advantage for them. If all the volatility price due to a great dependence
above assumptions are feasible, the 3rd sce- from two important supplier countries, i.e.
nario could be considered self-sustainable Libya and Russia, which held respectively
from an energy point of view. The energy a 9% and 38% share on 2013 imports. Rus-
interactions among the various plants in the sia became the main supplier in 2013 [75].
industrial area is very important as well as DRI production process has been success-
the introduction of advanced technologies fully implemented where there are large iron
and the research for energy recovery solu- ore mines and natural gas reserves.
tions and for re-use of off-gas and other sec-
ondary energy sources, by improving the
environmental sustainability of the selected 2.2.3 Comparison summary among
steelmaking production route. For instance, the different options
a series of innovative technologies for recov-
ery and reuse of waste heat can be deployed Table 6 shows the final overall compari-
both inside and outside the industrial area son among the five alternatives considered
401-page 15
 V. Colla et al.: Metall. Res. Technol. 113, 401 (2016)

for Piombino steelwork according to the as- worldwide are considered. This case-study
sumptions and hypothesis previously de- and the considered factors as well as the re-
picted. As far as the economic indicators are sults obtained are related to the steelwork
concerned, the assumptions related to the operating in Piombino and its particular col-
EAF location (i.e. close to the hot area or in location in Italy. For instance, the factors re-
a different area) can greatly affect CAPEX in lated to the needs to continue to produce
the EAF-based scenarios. The highest OPEX a certain amount of high quality steel for
is associated to the BF/BOF scenario and the railway products and, simultaneously, to ex-
highest reduction with respect to BF/BOF is ploit the steel scrap flow coming from the
obtained in the 5th scenario. The 5th sce- ship dismantling could be a significant crite-
nario allows savings of about 26% with re- ria which the investor should not neglect. In
spect to the 4th scenario due to the fact any case, the selected steel production pro-
r r
that MIDREX process is fed by COREX cesses will need to be flexible enough to meet
gas and not by natural gas. From an envi- not only the fluctuation on the prices of the
ronmental point of view, SO2 and NOx are raw materials market but also those related
significantly lower than in a conventional to the sale of finished products.
BF/BOF route: this is primaly based on the
fact that the coke oven plant and the sinter
plant in all the 4 scenarios are definetely dis- Acknowledgements
mantled. The best results in terms of CO2
emissions are achieved in the 2nd scenario,
The authors gratefully acknowledge Eng.
although the 3rd one obtains better results C.Motto and Eng. S.Simoni of Lucchini Spa for
in terms of PCCD/PCFD and SO2 emissions. their helpful and valuable comments on a draft
However, the environmental impact of all version of the manuscript. The sole responsibility
the alternative scenarios appear significantly of the issues treated in the present paper lies with
advantageous with respect to the conven- the authors.
tional BF/BOF route. The results shown in
the 5th scenario are an average estimation of
the values obtained in the 3rd and 4th sce- References
narios, since this scenario couples a smelting
reduction with a direct reduction technol-
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