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.
