6th Global Slag Conference 2010
22-23 November, Sydney, Australia
Reviewed By Robert McCaffrey, Conference Convenor
Images gallery for the Global Slag Conference 2010
The 6th Global Slag Conference has successfully taken place in Sydney, Australia, with 135 delegates from 27 countries in attendance and strong delegations from Asia in particular – notably South Korea. 23 papers on slag products and applications were presented and delegates were also able to visit the BlueScope Steel plant and associated slag product processing facilities at Port Kembla near Wollongong. The 7th Global Slag Conference will take place in Helsinki in November 2011.
The 6th Global Slag conference took place in Sydney at the invitation of the Australasian (Iron and Steel) Slag Association, and had the theme of ‘Making the most of the recovery.’ The conference covered global slag trends, slag technology, slag applications and slag in road-making. Networking was encouraged throughout the event, while delegates also enjoyed meeting exhibitors, including Loesche, Tapojarvi Oy and Kawasaki Heavy Industries in the exhibition area.
After a gracious welcome from the Governor of New South Wales, the conference started with a speech on Australia’s climate change policy response in the context of the Copenhagen Accord, from Mike Hitchens, CEO of the Australian Industry Greenhouse Network. He forcefully pointed out that under many metrics Australia is not a laggard in taking action on greenhouse gas emissions, and that its commitments to reduce those emissions in the future are comparable to the most stringent in the world. Those commitments, of course, will have an impact on the iron and steel slag industry and on the cement industry in Australia.
Charlie Zeynel of ZAG International next gave an overview of trends in the global slag industry. He pointed out that although the global iron and steel industry has had a very tough couple of years (so much so that slag has been in short supply in a number of areas), the prospects for the industry are strong. He did issue a warning that the demand for slag is likely to exceed even an expanded future supply, and suggested that cement producers who wished to benefit from slag use in the future should quickly move to secure long term supply contracts. Charlie reiterated his belief that there should be a virtuous circle of contacts and cross-fertilisation in the slag, cement, power-generation (ash production) and shipping industries, all of which are inter-dependent.
Karen Kiggins of the (US) National Slag Association then updated delegates on the situation in the iron and steel industry in the United States. The industry has historically produced in the region of 100Mt of steel for the last 25 years, but in 2009 the total reached only 63Mt: 2010 production is forecast to total 83Mt, so that a recovery is now underway. Karen noted that the use of slag-based products has been challenged by a number of different states and it is only through strenuous efforts that the use of slag continues in these jurisdictions. Karen stated – or perhaps understated – that the recent downturn in the US economy has led to increased competition and lobbying by the stone, sand and gravel industry.
Craig Heidrich of the Australasian (Iron and steel) Slag Association next spoke about the importance of establishing legal certainty over the status of slag. He pointed out that since Australia is a confederation of states, each one legislates differently on the status of slag, with some continuing to classify it as a kind of waste. He pointed out that some branches of government are enthusiastic about the increased use of slag - so as to decrease the use of natural resources - while others want to curtail or ban its use or to tax it. He called for more joined-up thinking, and for an increase in legal certainty in the status of slag.
Conference stalwart Alexander Koshi, formerly of Star Cement UAE and now with PEG India, then gave an overview of slag use in the Middle East, India and in Bangladesh. Steel production in India is due to increase to 110Mt by 2012, so that the availability of slag (and its use in slag cement) is expected to increase. However, the large annual production of fly ash (and the mind-numbingly huge stockpiles that already exist) mean that slag has to compete against ash as an alternative cementitious binder, keeping prices very low.
Robin Mellon of the Green Building Council of Australia then gave an overview of the organisation’s Green Star environmental rating system of buildings. As Robin stated, “The various environmental and human health impacts arising from building materials are reduced when use of virgin materials is limited and special attention is given to the selection of ecologically and health-preferable materials,” although whether he was referring to slag products was not explicitly made clear.
Dr Tomo Isawa of the JFE Steel Corporation, Japan, then gave an overview of slag in ‘the land of the rising sun,’ noting that steel production has been steady at around 100Mt for over 40 years, with slag production unchanged over the period at a mighty 40Mt/year. In a typical year, 17.6Mt of granulated BF slag is produced, 4.1Mt of air-cooled BF slag, 9.8Mt of BOF steelmaking slag, 2.4Mt of EAF slag and 5.5Mt of non-ferrous slag (including copper slag and ferro-nickel slag etc). One long-term trend has been the increase in granulation compared to air-cooling, so that around 80% of slag is now granulated. Dr Isawa pointed out the very useful public education and lobbying work of the Nippon Slag Association.
Nick Jones of the Harsco Metals Group next gave a brief presentation on the company’s experience of using steel slag fines in China as a cementitious binder. Steel slag is mixed with gypsum and reduced to minus 1mm, prior to being mixed with 15% fly ash and being ball milled to around 4-5000cm3/g. The product, called ‘Superfines’ is sold directly to concrete manufacturers, where it is blended in the mixtures as an additive. When substituting up to 50% of GGBFS in concrete, there is no loss of strength. The use of the product as a substitute for lime for the desulphurisation of industrial fumes is also currently being investigated.
The ebullient Jannie van Deventer of Zeobond proceeded on to introduce ‘E-crete,’ an alkali-activated fly-ash/BF slag concrete that has been commercialised in Australia. Jannie claimed a CO2 emissions reduction of around 80% compared to OPC-based concrete, but wouldn’t reveal the identities of his company’s proprietary alkali activators. Dr Alice Woodhead and co-authors next pointed out the importance of creating a sustainable supply chain to promote the creation of new EAF slag products. The paper revealed the startling startling fact that EAF slag only has 12kg of CO2 emissions associated with its production (post slag-tapping), compared to 50kg for natural aggregates.
Dr Sharif Jahanshahi of CSIRO next gave a very well-received paper on a new method of dry slag granulation and heat recovery, using a patented spinning disc. The technology, which is at an advanced pilot plant stage, obviates the use of water (up to 7t of water are used to make each tonne of granulate in the traditional ‘wet’ method), allows recovery of a proportion of the 1.8GJ/t of heat energy contained in molten slag, and also reduces sulphur emissions.
Edwin Peterson of Dust Control Technology, producers of DustBoss dust suppression equipment, explained how his equipment is used in slag processing plants to reduce fugitive dust emissions. A number of slag producers immediately sought out Mr Peterson to help with dust suppression.
Dr Timo Parviainen of the Outokumpu Tornio Works in Finland next introduced a newly-developed slag product processed from AOD and ladle slag. ‘OKTO-filler’ is highly suitable for neutralising acid waters or materials, and it is intended that the product will also be used in the future as a filler for both asphalt and in concrete.
Gala dinner and awards
Following the first day’s technical presentations, the delegates reassembled at a marquee at the Sydney Opera House for a Gala Dinner, serenaded by two of Australia’s up-and- coming young opera stars. At the dinner the Global Slag Awards 2010 were presented. Tapojarvi Oy won the award for Global Slag company of the year, while Holcim Trading won for Global Slag supplier of the year. Global Slag product of the year was won by ‘Cemstone,’ while the Global Slag plant of the year was won by Australian Steel Mill Services’ Port Kembla plant (an award that was met with exultant cries and much celebration). Slag-based discussions continued late into the night.
Second day
The second day of the conference saw the start of session 3, ‘Slag in use.’ Stefan Baaken of Loesche GmbH started the day by describing his company’s vertical roller mills for grinding slag. Geraldine Vanhamme of the University of Brussels then described her studies on the reactivity of BF slag in cement, a paper which gave rise to discussion of the possibility of forecasting the ultimate strength development of slag cement blends based on their composition. It became clear that composition alone is not enough to be able to forecast strength development, and other factors such as mineralogy, micro- structure, particle size distribution and the carbonation and pre-hydration level of the slag are also important. A model for strength development is still a long way off.
Professor Jay Sanjayan of the Swinburn University of Technology next explained his methodology for calculating crack widths in concrete: he pointed out that crack width and number is reduced in concrete blends with slag, and that the effect is increased with increasing slag content up to 65% substitution.
The youthful Alessandra Mendes of Australia’s Monash University next stepped up to present the findings of her recently-completed PhD on the fire-resistance of slag blended cements. She used a wide variety of experimental techniques to investigate the problem, including TGA, XRD, IR, silicon and aluminium nuclear magnetic resonance and synchrotron Si K-edge near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Alessandra found that the partial replacement of OPC with ground granulated BFS leads to an improvement in the mechanical properties of concrete test samples following exposure to temperatures beyond 400C.
A multi-authored paper by authors from Cementech and Boral Cement was given by Warren South of Boral Cement, explaining the blue-green phenomena of some BFS concretes. Using a trail of evidence worthy of a Sherlock Holmes story, Warren showed that the colouration is caused by the formation of hydrated iron sulphates, often in close proximity to metallic iron droplets in the concrete. The blue-green colour of these concretes generally fades in a few weeks as the coloured crystals are dehydrated to colourless monohydrate forms as the loosely-bound water of hydration is scavenged by CSH-forming reactions that continue to consume the remaining glass in the concrete. Khurram Shahzad Ayub and co-authors from the University of Gujrat in Pakistan next spoke about the possibility of adding ground steel slag to ordinary clay bricks. The bricks were found to have improved properties in a number of areas, and delegates were left metaphorically scratching their heads as to why slag-containing bricks are not more widely used.
The final session at the conference was dedicated to four papers on slag use in roadmaking. Nick Jones of Harsco Metals Group started the session by reminding delegates that steel slags not only have high polished stone values (PSVs) but that they have a marked tendency not only to retain those values during long service but to actually to increase them, leading to improved skid-resistance and high value for money for the road-builders.
Greg Arnold of Pavespec (NZ) next explained the phenomenon of rut-resistance in pavements, and pointed out that slags generally have very good rut-resistance compared to natural aggregates, due to the absence of clays in slag-based aggregates. The penultimate paper of the conference was delivered by well-known slag man Bill Bourke. He reported on the skid-resistance of a unique slag from New Zealand produced from a steel-making method using titanomagnetic ironsands. These ‘melter’ slags have been shown to have excellent skid-resistance, and are now increasingly being specified for roads across New Zealand.
The final paper at the conference was delivered by Dr Vijay Joshi of Australian Steel Mill Services, who pointed out that slag has been used for roadmaking (as roadbase) in Australia for more than 70 years, although this has only become widespread in the last 20 years. Increasingly slag is being used in a wider variety of applications, including for airport runways, highways and freeways, port construction, land reclamation and for hardstand areas. It seems that slag has a great future ahead of it.
Best presentation awards
The best presentation awards (as voted for by the conference delegates) were presented at the conference farewell party. Charlie Zeynel’s paper on global slag trends was voted into third place, while the paper by Dr Sharif Jahanshani and Dr Donghsheng Xie of CSIRO on a new dry granulation method for slag was second. However, the winner of the best presentation award was Alessandra Mendes of Monash University, for her paper on the fire-resistance of slag blended cements.
Field trip
In all, 40 delegates from the event took part in a post-conference field trip to BlueScope Steel’s Port Kembla works, where they saw slag granulation and a BF slag pour. Subsequently, participants had the opportunity to see all of ASMS’s slag product processing facilities, which, all told, create around 25 different slag-based products for sale to Australian industry.
Conclusion
Participants at the conference strongly praised the slick organisation of the conference, which was greatly enhanced by the cooperation and efforts of the Australasian (Iron and Steel) Slag Association. The technical content and networking opportunities at the conference were also very highly rated. Many international delegates were impressed with the spectacular city of Sydney and with the friendliness and openness of the Australians they met at the conference and field trip.
In 2011, the 7th Global Slag Conference will return to Europe, but will take place in Scandinavia for the first time. Given the concentration of high-quality research into slag behaviour and the long history of the use of slag-derived products in Scandinavia, the 7th Global Slag Conference, in November 2011 in Helsinki, is sure to be a great success. We look forward to seeing you there!
