European Commission - Research

04/11/2009

 Completed projects

ULCOS
Energy sources define routes to cleaner steelmaking

ulcosThe steel-making industry has already succeeded in developing processes with near-optimal efficiency in energy and resource usage, but there remains a need for further reduction in the levels of environmentally undesirable CO2 emissions. The Integrated project ULCOS is the first step in a very large two-part programme to pursue this goal, from concept building to industrial pilot-scale implementation.





Over the past few decades, steel-makers have made great strides in reducing the environmental impact of producing this vital material, which plays a role in virtually every aspect of modern life. Energy consumption of the best processes is close to the minimum physical requirements of the reactions involved; the use of available resources is rationally managed and recycling levels are higher than for all other materials combined.

With public concerns focussing increasingly on the threat of global warming, reduction of the ‘carbon footprint’ has now emerged as one of the most pressing challenges still to be faced. Despite the massive reuse of scrap, rising demand and the development of new high-performance alloys dictate the continued extraction of large volumes of new iron from iron ore. This is the stage making the largest contribution to around two tonnes of carbonic gas output for every tonne of steel produced, but today’s best practices offer little room for further cuts without radical innovation.

No easy answers

‘End-of-pipe’ solutions could bring savings of 25-30%, but would be difficult and very costly to apply. Yet the industry is looking at reductions of 50% or more to meet post-Kyoto targets for 2020 and beyond. This was the motivation for setting up the ULCOS programme, a highly ambitious five-year initiative that is the industry’s largest-yet transnational collaborative research effort.

Headed by ArcelorMittal and a core group of European steel producers, the complete programme comprises the Integrated Project launched in 2004 under the NMP priority of FP6, plus two intimately linked projects (ULCOS & IDEOGAS) supported via Europe’s Research Fund for Coal and Steel. These bring together 48 partner organisations from 14 EU countries, representing most of the European steel industry, its partners in the value chain, and a broad group of research institutes and universities. EU funding participation amounts to around €26 million in a total budget of €59 million.

The overall objective is to evaluate all feasible process options with a high potential for CO2 mitigation, and to develop the most promising candidates to pilot-scale implementation, with a view to readiness for industrial deployment within a 20-year timeframe.

Now in its fourth year, ULCOS began with a thorough evaluation of some 70 different processes, including the design and modelling of route flowsheets, as well as small-scale experimentation. By year two, the number had been narrowed down to five options, respectively based on coal, natural gas, hydrogen, electricity and biomass, to reflect the spectrum of energy source options that might be available in various future economic scenarios:

“None of these will be ‘no regret’ solutions,” observes coordinator Jean-Pierre Birat, of ArcelorMittal. “Achieving substantial decreases in greenhouse gas emissions means introducing breakthrough technologies that will add significant costs to the operation of steel mills. These will also require a great deal of research and development before they can be proven and introduced commercially. An ULCOS II programme is already being planned to take the results of the present work forward towards the ultimate goal.”

Improving the blast furnace

Most iron for steelmaking is currently produced in blast furnaces using coal in the form of coke and pulverized coal as the reducing agent to convert ore into raw metal. By now, blast furnaces have evolved into extremely sophisticated systems, operating at temperatures around 1 500°C and typically delivering 5 000-15 000 tonnes of iron per day. Today, they also gasify coal and supply energy that may be used in the steel plant itself, or even exported in the form of electricity.

The aim of the research in this area is to restrict the use of carbon (coal) solely to the prime purpose of making pig iron. This would be possible if the CO in the top gas emitted by the furnace could be separated from the CO2 and recycled as reducing gas back to the bottom of the stack. By limiting the amount of coal consumed, it would automatically bring a reduction in emissions. Furthermore, using oxygen rather than hot air to gasify the coal would make it possible to go a stage further by obtaining a clean enough CO2 stream for eventual storage.

A notable feature of ironmaking gases is that the main streams are rich in CO2 – from 25% to 98%, depending on the process. This makes it possible to select cheaper methods of capture. Of several investigated options, the non-cryogenic vacuum-pressure swing adsorption technology (VPSA) proved most efficient and cost-effective, although a cryogenic step would also be necessary to allow storage.

However, carbon capture and storage (CCS) are contentious issues, surrounded by legal and technological questions. Not least of these are the volume to be stored (estimated at up to 200 million tonnes per year in Europe) and the location of the plants that produce CO2. ULCOS looked at storage in geological traps, in terms of potential sites close to the main steel mills. The present knowledge of underground geology indicates that repositories exist within 100-200 km of most sites; their exploitation will depend on future technical progress, the pertaining political will and the cost of non-removal.

Promising route for early adoption

A large group of the project partners cooperated in the design of a ‘top gas recycling blast furnace’ (TGRBF), which has been validated by modelling and laboratory or bench-scale experiments and refined in considerable technological detail.

Three basic versions for injecting the recycled gas have been proposed, with various proportions of top gas injected via the normal air injectors (tuyeres) and through supplementary injectors located at the base of the furnace shaft. Modelling indicates that an even distribution between the two is preferable, Extensive tests on the experimental blast furnace of research partner Luossavaara-Kiirunavaara ab (LKAB) confirmed carbon savings of up to 24%, cutting CO2 emissions by 15% (65% with storage).

This is likely to be the approach allowing earliest adoption by the steel industry, although with limited CO2 mitigation unless storage becomes a practical proposition.

Extended collaboration in smelting

Smelting reduction processes offer another means to reduce iron ore by coal. Most are still at the conceptual stage, but they are easily run with pure oxygen, cutting carbon consumption and producing very concentrated CO2 streams ready for storage.

After exploring several variants, ULCOS sub-project ISARNA (the ancient Celtic word for iron) pursued a concept originated by Corus, using a smelt cyclone in combination with a coal-based smelter. This is highly energy-efficient, as all the process steps are directly hot-coupled, avoiding losses from intermediate treatment of materials and process gases.

Under an agreement announced in September 2008, major ore supplier Rio Tinto will collaborate with the consortium to develop a version combining the ISARNA method with its own Hismelt technology, currently undergoing ramp-up in Australia. (To reflect this merger, the project name has been changed to HISARNA.)

A pilot plant rated at 65,000 tonnes per year will be built at the Saarstahl site in Völklingen, Germany. This is due to start operations early in 2010, when a three-year testing phase will commence.

Direct reduction

Natural gas has replaced coal for steelmaking in countries where gas was abundant and cheap. Direct reduction employing a prereduction furnace and an electric arc furnace for melting is in principle the least CO2-intensive route, due to the replacement of carbon by hydrogen from the methane (CH4) gas and to the use of electricity. However, given current gas prices, it now accounts for only about 5% of world production.

Methods to attain the 50% reduction target were nevertheless examined, either by using direct reduction in an integrated mill, or by redesigning the direct reduction process.

In an integrated mill, limited prereduction to low reduced iron (LRI) with a 65% degree of metallisation, followed by finishing in a blast furnace proved to be an optimal balance. With low reduced iron charged as around 60% of the blast furnace burden, coke consumption fell to the required level.

This too could be an interesting solution to cut emissions of existing mills in the short term, if the price of LRI is right. Direct reduced iron can also be added as a substitute for scrap and ore in basic oxygen furnaces, again with a significant drop in emission.

The redesign of the direct reduction process entails saving energy wherever possible, cracking the CH4 by partial combustion, and using pure oxygen. Recycling the top gas is already part of the prereduction process, but oxygen operation generates a higher concentration of CO2. This new concept, which incorporates CCS, has been called ULCORED. A pilot unit is being planned in Sweden.

Scope for hydrogen?

Although not used at present for steelmaking, hydrogen is an effective reducing agent for iron ore. At temperatures above 800°C reduction takes place ten times faster than with CO, although the endothermic reaction requires heat input. An advantage is that it allows the production iron with an extra-low carbon content.

Hydrogen can be derived from natural gas by steam reforming, or generated by the electrolysis of water, neither of which is cost-competitive at present. Air Liquide has shown that it is possible to redesign the reforming step, to give a total process that is equivalent to the natural gas route in terms of CO2 emission. Projected developments by EDF also promise to lower the cost of water electrolysis.

Both methods could thus become attractive in times of severe carbon constraint, provided that hydrogen prices are not forced out of reach by demand from sectors such as the transport industry. Data from the ULCOS studies have therefore been incorporated into a full flowsheet design by Siemens-VAI.

Electrical technology revived

Electrically powered plasma torch technology developed for blast furnaces in the 1980s could be scaled up to complement the carbon reduction provided by TGRBF technology. Corus, ArcelorMittal and Europlasma have designed a 10-15 MW torch capable of being fitted to each of the tuyeres of a blast furnace, doubling the reduction achieved with TGRBF alone. Used with or without CCS, this offers a long- or short-term solution in circumstances where suitably priced electricity is available.

Electrolysis explored

Electrolysis is a technology that is commonly used to produce metals. There is no alternative for making aluminum or magnesium. It is gaining ‘market share’ in the case of copper, zinc and may be adopted in the future for titanium and tantalum. Electrolysis is also used for coating thin layers of metals on other metals (electrogalvanizing, tin-coating of steel) and for producing thin foils (copper electroforming). Concerning steel, the carbon-reduction route has become so efficient, large-scale and cheap that the price of electricity, an energy carrier that bears both the price of primary energy and of its transformation, has ruled out expectation of using electrolysis. Research on the subject has therefore been rather limited.

Electrolysis of iron ore could become appealing if carbon-lean electricity becomes accessible on a very large scale and at a competitive price. This is the only method available to produce aluminium and magnesium, and is attracting increasing interest for other metals such as copper and zinc. But, because carbon reduction is such a cost-efficient route to iron, electrolysis has not so far been given serious consideration for steelmaking.

Due to the lack of basic knowledge in this field, ULCOS conducted some small-scale experimentation to determine how it might be possible. This covered electrowinning technologies based on water solutions of Fe ions, as already used for coating in the steel industry, and high temperature electrolysis of molten salt or molten oxide, comparable to aluminium smelting.

Electrowinning in alkaline solutions proved to be very lean in energy and potentially straightforward to scale up. High temperature electrolysis of molten oxide exhibited the lowest energy need, but requires a great deal of development effort to reach industrial practicality. Work continues in both areas.

Return to the roots

Biomass, in the form of charcoal, fuelled the prehistoric Iron Age. Now, the CO2 challenge could induce a return to those roots, which hold the promise of carbon neutrality. ULCOS has considered the opportunities presented by dedicated plantations or agricultural residues as the sources of solid, liquid or gaseous biofuels.

Progress would need to be made in adapting furnace designs, but small blast furnaces in Brazil already run on 100% charcoal. The challenge for ULCOS is to bring a version of this technology to the EU.

Looking ahead

“While none of the proposed ULCOS processes are as yet competitive with the established blast furnace technology, the likely rise in carbon constraints could make them serious contenders within a decade,” comments Jean-Pierre Birat. “With the passage of time, the relative affordability of energy sources will change; electricity may then hold a special status and be able to replace coal and natural gas on a cost basis. The issues of availability and competition among users will also be important, especially for biomass, natural gas and hydrogen.”

In view of these conclusions, ULCOS identifies three particularly strong contenders for further study: carbon with CCS, natural gas with prereduction and CCS, and electricity via electrolysis.

“Greenhouse gases are a global problem,” Birat adds. “We aim to share our discoveries as widely as possible, but leading this pioneering research and securing ownership of the emergent intellectual property will certainly be to the advantage of Europe.

“A notable aspect of ULCOS is that, despite its size, it is proving remarkably easy to manage,” he concludes. “Cooperation between the partners and adhesion to the common objectives is outstanding. It bodes well for the follow-up stages of such a strategically important joint venture.”

Project partners

Ag der Dillinger HüttenwerkeGermany
Alphea Pole de Competence sur l'HydrogeneFrance
Arcelormittal Maizieres Research asFrance
Association pour la Recherche et le Developpement des Methodes et Processus IndustrielsFrance
Betriebsforschungsinstitut, VDEH-Institut für Angewandte Forschung GmbHGermany
BTG Biomass Technology Group bv The Netherlands
Bureau de Recherches Geologiques et MinieresFrance
Centre de Cooperation Internationale en Recherche Agronomique pour le DeveloppementFrance
Centre de Recherches MetallurgiquesBelgium
Centre National de la Recherche ScientifiqueFrance
Centro Sviluppo Materiali spaItaly
Consejo Superior de Investigaciones CientificasSpain
Corus Technology bvThe Netherlands
Corus UK LtdUK
Danieli Corus Technical Services bvThe Netherlands
Electricite de FranceFrance
Energy Research Centre of the NetherlandsThe Netherlands
Europlasma saFrance
Fundacion LabeinSpain
Geological Survey of Denmark and GreenlandDenmark
GVS s.p.a.Italy
Ilva spaItaly
Institut National Polytechnique de LorraineFrance
JRC Institute for Prospective Technologinal StudiesBelgium
Küttner GmbH & Co. KGGermany
L'air Liquide saFrance
Lhoist Recherche et Developpement saBelgium
Lulea university of technologySweden
Luossavaara-Kiirunavaara abSweden
Man Ferrostaal AGGermany
Mefos - Metallurgical Research Institute abSweden
Metalysis LtdUK
Montanuniversität LeobenAustria
Norwegian University of Science and TechnologyNorway
Paul Wurth saLuxembourg
Rautaruukki oyjFinland
Saarstahl AGGermany
Scuola Superiore di Studi Universitari e di Perfezionamento Sant'AnnaItaly
Sintef Petroleumsforskning asNorway
Ssab TunnplatSweden
Statoil asaNorway
Stiftelsen for Industriell og Teknisk Forskning ved Norges Tekniske HoegskoleNorway
Thyssenkrupp Stahl AGGermany
Universidade de AveiroPortugal
Universität KasselGermany
Voestalpine agGermany
Voest-Alpine Industrieanlagenbau GmbH & CoAustria

Key data

Project type: Integrated Project
Project title: Ultra-low carbon dioxide steelmaking (ULCOS)
Programme: Sixth Framework Programme, Priority 3 – Nanotechnologies and nanosciences, knowledge based multifunctional materials, new production processes and devices (NMP)
Total cost (NMP): €35.3 million – EC contribution: €20 million
Project duration: September 2004- August 2009 (60 months)
Coordinator: Jean-Pierre Birat – ArcelorMittal, France
More information: www.ulcos.org