This analysis proposes methodologies for developing multi-project baselines in the iron and steel industry
and suggests potentially appropriate values for these baselines. The potential volume of projects under
these different baselines is also estimated. Based on these inputs, conclusions and recommendations with
regard to the possibilities for multi-project baselines in the iron and steel industry are given.
This section gives an overview of the global iron and steel sector, including the important players and the
different processes and production routes. Also, an overview of energy consumption, carbon dioxide
emissions and regional distribution thereof is discussed. This section ends with a description of the iron
and steel sector in India, Brazil and Poland.
2.1 Iron and steel production processes
The iron and steel industry is the largest energy consuming manufacturing sector in the world. In 1990,
its
global energy consumption was estimated to be 18-19 exajoules (EJ), or 10-15% of the annual world
industrial energy consumption (WEC, 1995). The associated CO2 emissions are estimated to be 1425 Mt
(De Beer et. al., 1999). In 1995 this amount increased to 1442 Mt CO2, equalling about 7% of global
anthropogenic CO2 emissions1
. When mining and transportation of ore and coal are included, this share is
near 10% of total emissions. Fossil fuel combustion is the primary source of GHG emissions from iron and
steel production and energy costs represent 15-20% of steel manufacturing costs.
Currently, two processes dominate the global steel production. These may be generally be described as:
(a) the integrated steel mill, where steel is made by reducing iron ore in a blast furnace to make pig
iron which is subsequently processed in an oxy-steel plant; and
(b) the minimill, in which steel is made by melting scrap or scrap substitutes in an electric arc furnace
(EAF).
Other processes that are in use are either outdated, e.g. the open-hearth furnace, or so new that their share
in the world steel production is still small, e.g. smelt reduction processes and direct reduction processes
(e.g. Corex).
1 These include energy related emissions as well as process emissions (Olivier et. al., 1996).
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The iron and steel making process may be divided into 5 different steps (see Figure 1):
1. treatment of raw materials;
2. iron making;
3. steel making;
4. casting; and
5. rolling and finishing.
At the end of step 3, an intermediate product (molten steel) is common to all production routes. The
technologies and fuels used in the two main steel production processes can be used to further disaggregate
steel production. This report examines how emission baselines could be standardised for four “process
routes” to produce molten steel:
1. Blast Furnace - Basic Oxygen Furnace (BF-BOF);
2. Blast Furnace -
Open Hearth Furnace (BF-OHF);
3. Scrap-based Electric Arc Furnace; and
4. Direct Reduced Iron - Electric Arc Furnace (either coal based or gas based).
The energy intensity of final steel products can vary substantially, but adjustments to emission baselines to
take into account product differences are beyond the scope of this analysis.
The GHG emissions from iron and steel production in integrated steel mills are mainly from the
combustion of fossil fuels for energy (heat), electrical energy and the use of coal and lime as feedstock.
These emissions are primarily of CO2, although very small amounts of CH4 and N2O may also be emitted.
Only emissions of CO2 are assessed in this case study. Emissions from feedstock use is mainly from step 2
and 3 and some from step 1.
The blast furnace is the most energy-intensive step in an integrated steel mill and requires about 11-15 GJ
per tonne of pig iron produced. Of this amount approximately 7 GJ is used for the chemical reduction of
iron ore to pig iron. In addition, energy input is required to raise the temperature to a level at which the
chemical reduction can thermodynamically proceed at a sufficient rate.
Carbon (from energy sources such
as coal or coke) is used both as the reducing agent and as the energy input. The reducing agent (feedstock
energy use) may constitute up to 50% of the total energy demand of an integrated steel mill. Accounting
for which proportion of energy input results in energy-related emissions and which results in processrelated emissions is ongoing.
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Description of the steel production process
The integrated steel mill process starts with the production of coke (step 1) by heating
metallurgical coal in the absence of air in coke ovens*. The coke oven gas is fed into the blast
furnace (step 2) and the energy in the gas is used for the iron making. In some cases coke is
(partially) purchased. Iron ore is agglomerated in sinter plants or pellets plants2
. Coke, ore
and lime are fed alternately in the blast furnace (step 2). A hot compressed stream of air, the
blast, is blown from the bottom into the furnace. A gas is produced that reduces iron ore.
Molten pig iron, rich in carbon, is tapped from the bottom and transferred in isolated vessels
to the oxy-steel plant (step 3).
Here carbon and other impurities are removed by oxygen
blowing. Usually part of the input into the oxy-steel plant is scrap or other iron-bearing
materials. The characteristics of the crude steel are adjusted in a series of ladle treatment
processes. The casting of steel can either be continuous or batch (ingot casting) (step 4). The
cast steel is reheated, rolled and sent to a number of finishing operations. These final
operations depend largely on the type of steel that is produced. Integrated steel mills may use
the Open Heart (OHF) furnace or the Basic Oxygen Furnace (BOF). The electric arc furnace
mainly uses electrical energy. The largest part of the world steel production is made in
integrated steel mills.
* This step and associated capital expenditure, energy use and GHG emissions, are avoided in the
Corex process.
The ranges in energy use to produce molten steel for a given technology type are influenced by the quality
of fuel and iron/scrap inputs, but also by variations in the relative proportion of fuel input used. The share
of electricity in the total energy demand varies from plant to plant but is not reported separately. Based on
statistics published by IISI (IISI, 1996) this share is estimated to range from 2.5 to 7% of the final energy
use in an integrated steel plant. Integrated steel mills may generate (part of) their electricity use and
purchase the remainder. Electricity can account for between 50-85% of total energy inputs to an EAF3
. The
GHG-intensity of steel produced by the same production route in different plants will vary according to the
fuel used and to differences in GHG-intensity of electricity.
The lay-out of the energy system varies considerably from plant to plant. The potential to recover energy
contained in process gases, heat and pressure energy will also vary from site to site, depending on its
layout.
A minimill uses scrap (or scrap substitutes) rather than iron ore as its material input. The scrap is melted in
an electric arc furnace to produce crude steel, which is cast, rolled and given a final treatment. However,
due to contaminants in the scrap the quality of the steel produced in an EAF may be lower than that of oxysteel.
The demand for high-quality scrap, i.e. low in contaminants, has increased significantly and has
pushed up the market prices for such scrap. Therefore, minimill steel producers also use other iron-bearing
materials as raw material. These materials are usually sponge iron, produced in direct reduction plants, or
(hot) pig iron, produced in a blast furnace. The electricity consumption from an electric arc furnace has
come down from about 550 kWh/tonne liquid steel in 1970 to 350 kWh/tonne liquid steel in the late 1990s.
The theoretical minimum is 300 kWh/t. Obviously, the CO2 emissions associated with such energy use
2 Pellet plants are more frequently located near the ore mine than at the site of the integrated mill.
3 Jeremy Jones, Electric Arc Furnace Steelmaking,(www.steel.org/learning/howmade/eaf.htm)
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depends on the way the electricity is produced. The range of products produced by minimills used to be
limited to long products only, because the quality of the scrap was not high enough to produce flat
products4
. Moreover, the investment costs for a hot strip mill are high. However, with the availability of
scrap substitutes and, more important, with the introduction of new casting techniques, minimills have
entered the market of flat products.
The energy demand for direct reduction varies from 13 to 18 GJ per tonne of sponge iron. Energy in the
form of natural gas or coal is used. Scrap preparation requires different amounts of energy, depending on
the quality of the scrap.
