Image gallery for the 14th Global Slag Conference which took place in Aachen, Germany on 26 - 27 March 2019.

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!

5th Global Slag Conference and Exhibition 2009
23-24 November, Brussels, Belgium

Reviewed by Dr Robert McCaffrey, conference cconvenor

Over 140 delegates from nearly 40 countries assembled in Brussels at the end of November for the 5th Global Slag conference and exhibition. As ever, the delegates represented the world’s largest slag producers, as well as the main slag users, including cement and concrete groups from around the world. 

The 5th Global Slag Conference took place in the shadows cast by the global recession. Iron and Steel companies world-wide have cut their production by 50%, so that slag production has also fallen by a half. However, this has given rise to a new dynamic in relations between the slag producers and slag users. Cement demand has typically not fallen by as much as slag production, so demand for slag (compared to how much is available) has increased. Given that CO2 emissions permits may increase in cost in the next couple of years, the cement producers are also scrambling to try to secure long-term supplies of (non-CO2-emitting) slag. Such was the intruiging background to the conference.

The first speaker was Charlie Zeynel of ZAG Industries. He stated that in his experience, the total volume of slag traded around the world has dropped. However, slag supply has become very tight, and slag prices have doubled. Slag is now even being shipped from Japan as far as France and Belgium (after the closure of a European steel works situated next to a slag-grinding plant). Japan has started to increase its production of steel and slag due to an increase in demand from China, although overall slag demand has dropped due to the fall in cement demand (which has led to widespread clinker grinding overcapacity).

Charlie pointed out that around 25-30% of pig iron tonnage is composed of slag, and that an increasing percentage of slag is granulated - increasing from 48% woldwide to 68% worldwide in 2010, or 292Mt of the 450Mt of blast furnace slag produced worldwide. However, the proportion granulated varies from country to country. In the US, only 35% of BFS is granulated, 48% in China, 73% in the EU and 79% in Japan, while in India fully 83% of BFS is granulated.

Cement demand in Japan is forecast to have dropped by 20% through 2009, as big infrastructure projects have been cancelled, with the effect that a greater proportion of the locally-produced slag and GGBFS is now available for export. As Charlie said, “Slag supply from China is likely to dramatically increase, but the quality is suspect.” He started and finished his presentation with a call for the iron and steel industries, the power companies (and their ash-producing units) and for the shipping companies to come together to engage in some ‘joined-up thinking.’

Stuart Reynolds of globalsteelconsultants.com backed-up Charlie’s remarks on slag trends, and mentioned that a new report on slag markets worldwide is now available.

Hendrik van Oss, a specialist on cement, ferrous slags and coal combustion products at the US Geological Survey, spoke on the environmental issues affecting the use of slag and similar materials in the US construction sector. Hendrik mentioned that new regulations on fly-ash suggest that it should be classified as ‘hazardous’ if it is stored, but that it would be ‘non-hazardous’ if used ‘beneficially.’ However, Hendrik suggested that power plants may cease to make fly-ash available for third-party use for fear of incurring product liabilities.

Heather Booysen of Samancor Chrome then gave a summary of the situation for slag in South Africa. In 2006 the government decided to de-list ferrochrome slag as a hazardous material, to try to ensure that the material was used in a more productive manner. Samancor managed to have its materials passed for use, before the ‘door of opportunity’ closed to other producers. The material is now classified on the basis of its most hazardous constituent, and this has allowed it to be used in bricks, concrete products and road building, although Heather says that it is a big job to change perceptions of the materials. A new waste management act is now promoting the re-use of waste, and this is expected to increase the proportion of slag used in South Africa.

Renaat van Geel of Thermo Fisher Scientific started the technical sessions at the conference with an overview of how slag may be analysed using the ARL 9900 integrated XRF-XRD workstation. The machine can analyse pressed powdered pellets, directly moulded pellets and even in-situ slag. As always, longer counting times provide higher accuracies and lower detection limits.

Daneel Geysen of the University of Leuven next spoke on the link between slag chemistry and valorisation. The composition of hot slag can be controlled by variation of the raw materials, the furnace type, additions, the targets that the furnace is set, slag foaming and even by the personnel operating the equipment. The control of the composition of cooling slag can be controlled by the mixing of slags, through control of the cooling rate (either in the slag yard or via box cooling), via water spraying, slag layer thickness and of course through the operation of any granulating device. Magnesium is normally added to the slag to stop the dissolution of magnesium from slag pot refractories - the slag must be saturated in Mg but not oversaturated. The transition from beta-C2S to gamma-C2S can be prevented by adding boron to the slag, although this will reportedly soon be banned. The CaO/SiO2 target for the slag needs to be optimised, as does the cooling profile for the slag. Cr(VI) leaching potential can be reduced by increasing the development of crystalline spinel formation. Daneel also stated that reducing the slag pH will tend to reduce the leachability of minor constituents.

Vlad Popovici of Bredero Shaw, Canada, then went on to speak about the possibilities for valorisation of Electric Arc Filter (EAF) dust. Most recycling options for EAF dust produce varying amounts of zinc oxide as a valuable by-product, due to the variability of the composition of the original dusts, as well as further EAF dust recycling slag. Vlad forecast that EAF dust recycling slag tonnage will increase from the current level of 1.5Mt/year to around 4.5Mt/year within 10 years.

New building material

Mieke Quaghebeur of the Flemish Institute for Technologicial Research (VITO) gave details of an innovative new product ‘Carbstone,’ which uses fine-grained steel slags treated at high pressure with CO2 to form a high-strength building material. The carbonated materials “can compete with concrete products and have excellent environmental and technical properties, as well as the advantage of sequestering 180-200kg CO2/t of slag.” The process can use different waste materials, including LD slags, stainless steel slag and furnace bottom ash, although the final mix needs to have the correct composition, the right suite of reactive minerals and the correct grain size profile. The ingredients are mixed with water, shaped in a mould and cured with CO2, with carbonation increasing (intriguingly) from the centre outwards. A pilot installation for 10,000t/year of slag use is currently planned for 2010.
The next paper, by co-authors from Recmix Belgium, was also on the valorisation of stainless steel slags. Evelyne Nguyen pointed out that beta-C2S-rich fines can best be used as a filler in self-compacting concrete, while gamma-C2S-rich fines are best used as artificial aggregates for road construction, or recycled as slag foaming agents.

Professor Roberto Roberti and co-authors from Italy and Austria then spoke about the Slag-Rec project for direct dry granulation of EAF slag, using a new machine. The presentation was met with lively questioning.

Gala dinner and Global Slag Awards

The conference social evening took place at the stunning Brussels Atomium, on the site of the 1958 World Fair. Following an hour or so of roulette and blackjack (delegates had been issued with 300 ‘slag dollars’) attendees sat down to local dishes as the globular room swayed slightly in the wind (the ‘globes’ of the Atomium represent an iron crystal - appropriately - magnified 165 billion times). It transpired that Mari Kurttio of Tapojärvi Oy (lower right) had won the most (possibly with the help of her colleagues) at the tables, and was awarded the ‘best gambler’ award.

During the dinner, the Global Slag Awards were presented. Cloos S.A. was awarded the ‘company of the year’ award, after gaining five new contracts in a tough year. Ecotrade was the popular winner of the ‘slag supplier of the year’ award (see right), while ArcelorMittal Stainless Steels’ Chatelet plant in Belgium was awarded the ‘plant of the year’ title. Slag product of the year was awarded to Carbstone, see above, while the Global Slag ‘personality of the year’ went to Nigel Cooke of Lafarge Cement UK, for his previous work (and future work, in the same vein as Obama and the Nobel Peace Prize) on ash and slag use in cementitious products.

Second day

The second day concentrated on slag grinding and handling and on slag applications. Gérard Marchal summarised a lifetime’s work in only 25 minutes with his presentation, ‘What I have learned in a lifetime in comminution’ - an independent assessment of the options now available for slag grinding. Stefan Baaken from Loesche next gave an overview of slag grinding using the Loesche 2+2/3+3 vertical roller mill, and was treated to an extended questioning session, such was the level of interest in the possibilities of his equipment. Conference stalwart York Reichart of Gebr. Pfeiffer rounded-off the session with an overview of operational data from the MPS vertical roller mill for producing slag powder and slag cement.

Davide Gambarotta of Italian-international bulk materials handling company Gambarotta-Gschwendt srl gave a thought-provoking presentation on state-of-the-art handling for slag, and Ben Laenen, on behalf of colleagues from VITO, spoke about an integrated evaluation strategy for the recyling of metallurgical slags, particularly with regards to Belgian slags.

The final presentation at the conference was given by Erki Unn of Estonian company Silteh W2P, on thermal decomposition and valorisation of waste using a molten slag bath. The original technology was developed by the Gintsvetmet Institute in Russia and uses a a sparked molten slag bath at a temperature of 1250-1600°C to thermally decompose industrial, municipal and even hazardous wastes, with slag/cement, steam, electricity, metals, gases and potable water as some of the by-products. Once again, the fascinating presentation was rewarded with intense questioning from the assembled delegates.

Awards and prizes

At the conference farewell reception, a number of awards were presented. Loesche won the ‘best exhibition stand’ award. Following voting by delegates, Heather Booysen of Samancor Chrome was the valiant fourth-placed presenter, while late replacement Erki Unn of Silteh W2P was third. In second place with his very interesting presentation on trends in the global slag markets was Charlie Zeynel of ZAG International, but Mieke Quaghebeur (left) of VITO, the Flemish Institue for Technological Research was awarded the ‘best presentation’ award.

4th Global Slag Conference and Exhibition 2008
10-11 November, Strasbourg, France

Reviewed by Dr Nino Mancino, conference co-convenor

The 4th Global Slag Conference has taken place in Strasbourg, France, with 140 registered delegates from 35 different countries. Despite a severe downturn in the steel industry, representatives from the main steel groups were present, as well as many of the main users of slag, including the world’s largest cement producers.

Day One

After a convivial cocktail reception on the evening of Sunday 9 November, the conference opened the next morning with a survey of the main trends in the global slag industry by Dr Robert McCaffrey, conference co-convenor. The main points that the industry has to contend with are the sudden collapse in global steel demand (producers have cut back by 15-40% on scheduled production, and this will lead to subsequent decreases in slag supply – and possible increases in slag prices); decreases in cement demand in major economies such as the US, Spain, Ireland and the UK (but possible increases in government infrastructure spending – as indicated by the Chinese government’s announcement that day of a US$600bn infrastructure investment package) and the collapse in global freight rates by over 90% compared to their peak in mid-2008 (possibly leading to an increase in the amount of slag shipped over long distances).

Softer challenges foreseen for the slag industry include the problem of changing the perception of slag with the public, with engineers and with specifiers; the ongoing effort to change building codes and standards worldwide to allow the increased use of slag; the impending decision on how the EU ETS Phase III will work (and will it lead to increased carbon leakage, with carbon-intensive industries relocating outside the EU to avoid CO2 taxes); and the question of where the benefits of using slag will reside (there is some suggestion that slag prices do not yet adequately reflect the benefit that the cement industry derives from slag and this is a point that the iron and steel industry is keen to address). The short presentation raised more questions that it answered, but it also gave the assembled delegates something to think about through the event.

Charlie Zeynel of ZAG International next spoke about trends in the market for cementitious materials. Charlie pointed out that cement demand in Russia has fallen precipitously, that demand in the Middle East is slowing, that Turkish producers are no longer sold-out, that export prices for cement are in the process of collapsing and that cement companies are resorting to drastic measures to stem the flow of cash from their operations. Charlie suggested that the world – led by newly-elected president Obama – will steadily become more serious about tackling global warming, and that the cement and steel industries will be fundamentally affected by the changes. Global warming certainly provides a strong impetus towards the increased use of slag in cement. In a ‘glass half full’ moment, he also pointed out that, despite the current dramatic falls in US cement demand (down from 114Mt in 2007 to a forecast 94Mt in 2009), the population of the US is set to increase by 63m by 2030, and that cement demand will rise by over 50Mt in the same period.

Philippe Lacroix of ArcelorMittal was next up, and pointed out to delegates that they should look beyond the current market instability; “Look at the medium to long term – the fundamentals of the industry are strong. Our main product is steel, but we also make other products – byproducts – that have a lot of value-added. Our aim is to produce a consistent slag product. We produce around 115Mt of steel per year, with 300-400kg of slag produced per ton of hot metal. Of this total, 19Mt of slag is granulated each year (with the rest air-cooled) but with a 90% target (25Mt) for granulation due within five years. The blast furnace, concluded Mr Lacroix, “is the most economically-efficient and most robust technical solution. We will continue to produce slag for many years to come.”

Marc Fixaris, also of ArcelorMittal, then spoke about the use of Electric Arc Furnace (EAF) slags in the construction industry. EAF slags have been problematic, since they typically contain more than 1% of free lime, and are hence prone to expansion and cracking when used as road base. However, ArcelorMittal has patented a process that takes these so-called ‘black slags’ and blows oxygen and sand into the still-molten LD slag. Free lime in the slag binds with the SiO2 in the sand to form a stable calcium silicate, decreasing the free lime content to below 1% and allowing the slag to be used in road construction and in concrete blocks. As Mr Fixaris deftly put it, “the cost of beneficiation is lower than the value added,” suggesting that the process is profitable.

Siegfried Strasser of KHD then gave a beautifully frank history of the development of the high-pressure grinding roll by his company. Due to the generation of micro-cracking, second and subsequent passes of the ground slag between the rollers require lower specific grinding energies. In a second generation of grinding systems, KHD added deagglomeration of the ground slag, but early systems had problems with wear and coatings – and also had a maximum moisture content ceiling of 6%.The third generation systems used a cascade-type static ‘V’ separator, which could handle materials with up to 18% water content, with fewer wear problems. The rolls of the grinding system started to use studs of hard metal embedded in the rollers, with a layer of compacted slag in between the studs as an autogenous grinding bed. With this system, KHD boasts up to 14,000 hours of maintenance-free operation. The latest generation of the system is named ‘Comflex’ and uses a V-separator, a dynamic separator and a series of cylones to provide high-efficiency grinding with optimised particle size distribution.

Dennis Todd of Wear-Con then spoke about his company’s solutions to wear in an American slag drying facility, which was previously beset with problems. Such was the efficacy of Wear-Con’s solution that the company asked him to come back and reline the dryer to give it a 10-year guaranteed operating lifespan.

Dorival Tecco of Welding Alloys continued the theme by speaking about the options for optimising the production of slag grinding vertical roller mills by hard-facing the rollers with his company’s advanced grinding materials in which the formation of calcium carbide needles is suppressed and which are replaced by distributed fine carbides and nitrides, leading to high abrasive resistance and long life spans.

Finally, a representive from the Changsha Carrie Heavy Industry Co Ltd spoke about his company’s capabilities in producing slag pot carriers.

Gala dinner and Global Slag Awards

Before the Gala Dinner, the delegates were treated to a guided tour inside the beautiful Strasbourg Cathedral. The tour included a brief history of the city, as well as a demonstration of the unique astronomical clock that is the hallmark of the cathedral. After a pleasant stroll through the city the delegates made their way to the Salle Mozart in the heart of historic Strasbourg. The young Amadeus Mozart gave a recital here in 1778 and the hall was subsequently named in his honour. The meal consisted of three courses of delicious food, whilst in the background the melodic tones of a professional singer added to the delightful ambience of the occasion.

The Global Slag Awards 2008 were also presented during the course of the evening. The winner of Global Slag Usage Innovation was POSCO of South Korea for its intelligent use of slag as a replacement for lime in an EAF mini-mill. The move has led to significant cost savings and creates a useful recycling avenue for this type of slag. The winner of the Global Slag Product of the Year 2008 was given to MIG material innovative gesellschaft mbH. MIG has pioneered a range of water-soluble chromium(VI) reducers for treating slag and other cementitious building materials. Chromium(VI) contamination is a serious health hazard that MIG’s CEM Protector products will help to alleviate. CEMAG Anlagenbau GmbH was the proud recipient of the Global Slag Product Innovation for 2008 for its newly-launched Beta Mill. Helge Wilhelm happily received the award and gave a presentation on this technology on the morning of day two.

The final award of the evening was in the category of Global Slag Personality 2008 and was bestowed upon Charlie Zeynel of ZAG International. Charlie has been a passionate advocate of the use of cementitious materials – in particular slag – for many years. In addition, Mr Zeynel continues to press for greater dialogue between the four key industries who are involved in the production, use and transportation of slag-based materials – namely the steel, power, cement and shipping industries.

Day Two

Helge Wilhelm opened up the second day with a description of CEMAG’s development of the Beta Mill. This innovation – announced for the very first time in the world at the Global Slag Conference – promises to specifically reduce specific grinding energy for slag grinding compared to other grinding systems. Intense questioning and debate took place at the end of this fascinating presentation, and further details are eagerly anticipated.

The next presentation was on the topic of the physical processes of molten slag granulation, by Dr Leonid Yerihemzon of the German Association of Russian-speaking Scientists. Dr Yerihemzon described a case study from a Ukrainian metallurgical plant and highlighted the effect of different criteria such as water jet speed, slag flow and heat flux density on granulation efficiency.

After the subsequent coffee break the delegates listened to a lively and interesting presentation from Sang-tae Cha of Korean firm Ecomaister. Mr Cha spoke about the applications of Ecomaister’s Precious Slag Ball (PS Ball). These applications include roofing granules, road paving, abrasive blasting materials, permeable reactive materials and poly-concrete materials. When asked about the latter, Mr Cha explained that PS Ball is compatible with cement, meaning that the two can be combined to create a mixed concrete with added strength.

The next paper was delivered expertly by Peter Seymour of Ecocem on the topic of GGBFS cements and the value that they add to cement construction. Ecocem is a vigorous promoter – as well as producer – of this product and is keen to expand its use as an “technologically and environmentally superior” alternative to normal Portland cement. According to Mr Seymour, the fact that Ecocem produces and sells just one product gives it an advantage over the larger cement companies who produce slag cements only as part of a wider range of cement products. Perhaps unsurprisingly, Mr Seymour’s presentation evoked robust but courteous debate between himself and representatives of some traditional cement companies.

After a generous buffet lunch the next speaker was Dr Nilforoushan of the University of Shahrekord, Iran, on the subject of using steel slags for water filtration. Dr Nilforoushan’s research shows that potentially dangerous levels of manganese (Mn2+) and ferric (Fe3+) ions can be extracted from contaminated waters by the use of steel slags. Moreover, these slags shows a degree of selectivity in the types of heavy metals they extract. Dr Nilforoushan intends to expand his research to examine the efficacy of these slags towards removing other heavy metal ions apart from Mn2+ and Fe3+ ions.

The penultimate presentation was given by In Soo Jang of POSCO. Mr Jang spoke about POSCO’s project that uses slag as an alternative to lime in steel production. Two of the major processes involved in steel production are decarburisation and dephosphorisation. These two high temperature processes are made more efficient with the inclusion of free lime (CaO). Free lime is itself an expensive raw material, so POSCO’s research team have used the CaO contained in EAF slags (typically around 45% by wt) as their source of lime. As well as process improvements, POSCO claims to have achieved significant financial savings with this approach as the costs associated with sourcing raw lime are no longer necessary.

The final presentation was delivered by another POSCO representative – Bo Ha Park. Mr Park delivered an extemely interesting presentation on the use of so-called ‘Bioslag’ in marine environments. Climate change and the increase in average sea temperatures is causing coral whitening, especially around the Korean peninsular. POSCO has devised a novel way to reverse this by using steel slags as a type of seaweed bed for the rehabilitation of damaged coral reefs. The rationale behind this methodology is actually quite simple: slags – positioned in amongst coral reefs in the form of blocks and stones of varying sizes – act to sequester CO2 from the sea. This, over a period of time, allows the coral reefs to regenerate. POSCO has demonstrated this over several sites around the Korean coastline, allowing reefs and other types of marine life that depend on the reefs to flourish. The following question-and-answer session established that these Bioslag reefs would need to be replenished every 10 years or so, especially if sea temperatures continue to increase in the future.

Farewell reception

The farewell reception was held in the opulent surroundings of the EU Parliament building. Delegates were escorted around the complex, shown a DVD that explained the workings of the EU Parliament and then taken into the huge Parliament chamber itself. Farewell cocktails were accompanied by the award of the conference prizes. In the category of Best Presentation the delegates voted for Bo Ha Park of POSCO as the winner; Sang-tae Cha of Ecomaister came in second position and Peter Seymour was in third place.

Field trip

A group of around 45 delegates participated in the trip to ArcelorMittal’s Florange plant visit. We were warmly welcomed by members of ArcelorMittal’s welcoming team and given a detailed introduction to the Florange facility. The delegates were then treated to a trip around the plant, followed by a truly delicious lunch. Global Slag would like to express its sincere thanks to ArcelorMittal for opening its doors to the conference’s delegates.