16th Global Slag Conference, Exhibition & Awards 2024
23 - 24 April 2024, Dubai, UAE
The 16th Global Slag Conference has successfully taken place in Dubai, UAE, with 175 registered delegates from 32 countries, two field trips to slag grinding plants and the Global Slag Awards dinner at a spectacular camp on the edge of the Arabian Desert.
View the conference photo gallery here
Joe Harder of OneStone Consulting started the event with an overview of trends in the global slag industry. Only 40 countries produce iron. The traditional means of producing pig iron, using blast furnace (BF) technology, is slowly changing, partly due to the intensity of CO2 production. Directly reduced iron (DRI) production may amount to perhaps 400Mt by 2050, but blast furnaces will still predominate, while steel scrap recycling using electric arc furnaces (EAF) will become more common through replacing blast furnaces. Carbon recycling from blast furnaces and many other technologies are being developed and trialled worldwide. The world iron ore market is dominated by low and medium grade iron ores, which can be used on the BF-BOF process, but not in the DRI and EAF routes, which require higher grades and scrap steel respectively. Given the trend towards lower grades, and increases in BF capacity especially in Asia, the global supply of slag is expected to increase (in Asia, at least), even while pig iron production in North America and Europe will decrease. Imports of granulated blast furnace slag (GBFS) into Africa are likely to increase dramatically. Joe pointed out that DRI slags do not go through a melting phase and have no cementitious properties.
Charles Zeynel of ZAG International, the next speaker, has been proclaiming the value of supplementary cementitious materials (SCMs) for several decades, but demand has finally caught up with supply due to decarbonisation and simple economics. Charlie pointed out that many more different types of slags are now being valorised, alongside other SCMs, due to the carbon intensity - and production expense - of OPC. The global market for GBFS was around 380Mt in 2021, and is expected to grow at a CAGR of 3% per year until at least 2035.
The next speaker was Arusha Ahmed Khan of Cemcoa, part of the Shun Shing Group (owners of Green Cement slag grinding plant in Dubai, location of the event’s first field trip and picttured above)), who gave an overview of Asian slag markets. Crude steel production in Japan has been slowly falling, but the country is still a major exporter, primarily to Asian markets but also to the US. EAF steel production is increasing throughout Asia. China far outweighs the rest of the world in crude steel production,and now exports a similar level of GBFS - 10Mt annually - as Japan. Chinese domestic demand is weak, due to a construction slump, and exports go to Asia and to the Middle East. India is the second largest steel producer - at 143Mt in 2023 - but only 2.4Mt of slag is exported. Indian steel production is expected to amount to 300Mt by 2030. Vietnam is also a major steel producer - expected to increase to 21Mt by 2025 - although GBFS exports are still below 1Mt. Indonesian BGFS exports also total around 1Mt, while Malaysia exports around 300,000t per year. Despite producing 65Mt of steel each year, Korea exports very little GBFS, instead consuming the majority of its 12Mt of slag domestically. One of the key importing countries is Bangladesh, which lacks its own limestone and clinker production facilities, and which is required to import both clinker and other SCMs including slag, of which it brought in 5.9Mt in 2023. Taiwan ROC imported nearly 4Mt of GBFS in 2023, while Singapore imports only ground GBFS (GGBFS) - nearly 2Mt in 2023. The UAE imported 3Mt of GBFS in 2023, and demand has been supported by local regulations stipulating the use of slag in concrete mixes. Saudi Arabia imported 1.5Mt of GBFS in 2023, in support of its various mega-projects. Qatar and Kuwait also import GBFS, albeit in lesser quantities.
Charles Ochola of the US National Slag Association (NSA), spoke about the regulatory situation for slag products in the 50 states that make up America. Regulations on the use of slag-based products varies from state-to-state, with little harmonisation. Chemical analyses of a limited number of samples of slags by the US EPA has raised some concern for the regulators, primarily due to the potential presence of manganese and hexavalent chromium in stainless steel slag (and not in other slags), but the US NSA has pushed back on many aspects of the analysis. At the same time, the US Department of Transportation has awarded US$5m in funding for research on the use of steel slag in cement and concrete.
Sharon Morgan of US law firm Fox Rothschild spoke about the process of obtaining permits for the construction of a slag grinding facility in Wilmington, Delaware, while Lisa Bhadsavle of WALAN Specialty Construction Products introduced the Gebr. Pfeiffer ‘Ready2Grind’ modular vertical roller mill (VRM) that is being used at the plant. The compact plant site is adjacent to the waterfront of the Port of Wilmington, and particular effort has gone into reducing any dust emissions from the plant, with an oversized dust collector. Sharon described the permitting process as ‘running the gauntlet,’ since many agencies are involved in allowing the project to go ahead. “Don’t give the regulator anything to worry about,” said Sharon, and she also emphasised that environmental justice is becoming more important, and seeks to avoid disadvantaging poorer communities. Having your paperwork in order and up-to-date is extremely important in the process, and getting the stakeholders (regulators, community, customers and supporters) on board is vital, as is generating local jobs and being a good neighbour. WALAN modified truck routes to the plant to eliminate traffic through residential areas, added tarp coverage of stockpiled materials to avoid dust, and conducted long-term studies to reduce or eliminate any impacts on the local communities.
Youssef Tawfik next reviewed Green Cement Factory LLC - scene of the field trip the previous day. He lamented that the market in the UAE has shrunk by 40% since 2019, partly due to Covid, but inward investment, government-backed infrastructure projects and relocations to the emirate have started to bolster the construction industry once more, creating demand that is eating into the cement production overcapacity in the region. The Green Cement grinding plant has a 1Mt production capacity, using a Loesche VRM, 30km from Jebel Ali port, situated in Dubai Industrial City.
Kalevi Kostiainen of Magsort Ltd then spoke about his company’s material recovery plants (MRPs), which focus on recovering the metal fraction of slags, and which then further valorise the slag into profitable mineral resources. The products (including from steel and ladle slags) may be used as alternative raw materials (ARMs) for clinker manufacture, fed as part of the raw meal and generating a variety of economic and environmental benefits. Kalevi said that, even in the absence of a CO2 tax, using the slag as an ARM has a net cost benefit of Euro22/t of slag used. These slags may also be introduced into the cooler, where the heating activates the slag, and speeds up cooling of the clinker, while avoiding the formation of Cr6+ in the clinker. Up to 7.5% steel slag may be dosed as an ARM. Kalevi concluded that steel slag can be activated thermally and chemically, and in the presence of GGBFS. Magsort has a patented solution to eliminate the formation of Cr6+ in the kiln. Erimates Steel Arkan will build the first MRP plant for the cement industry.
Jagabandhu Kole of JSW Cement next spoke about the characterisation, reprocessing and effective recycling of steel slags in cement clinker production.
Nie Wenhai of CNBM Group-Sinoma gave a ‘bonus ‘ last-minute presentation on slag use in China. GGBS production reached 110Mt in 2022. Sinoma-TCDRI has commissioned more than 240 VRMs for slag, all but a handful in China, and total design capacity is more than 100Mt. An optimised grinding zone structure, newly-improved classifier and more sophisticated process control has improved slag grinding, while table diameters up to 6.6m can already be supplied with capacity up to 300t/hr at 4200 Blaine, and with 7m tables coming in the future. Nie Wenhai explained that LD slag could be used for cement production once crushed, metal extracted and then processed with steam, and he gave a reference list of plants in China using the process with up to 15% LD slag used in the raw mix.
Bipin Sharma of BSRM Bangladesh gave the final presentation of the day, looking at induction furnace slag (IFS) and ladle refining furnace slag (LFS). BSRM melts 2.2Mt of steel each year, using 11 induction furnaces, using 90% scrap and 10% sponge iron. LFS and IFS are handled in separate processing facilities to recover magnetic sand to produce valuable co-products. The IFS is marketed in thee different size fractions. Around 22 billion bricks are made in Bangladesh each year, contributing 1% of the country’s GDP, but producing 17% of the pollution, while denuding the country’s topsoil. IFS can be used instead of brick chips, to make unipaver blocks and hollow blocks. Demand for the sub-8mm fraction outweighs demand, but the +8mm fraction has yet to be approved for use. LFS slag is weathered for 2-3 months to help to reduce free lime, and then is size-separated and magnetically sorted before being made available as a soil conditioner, since 37% of cultivatable land in Bangladesh is classified as acidic and the slag is strongly alkaline. The LFS could be used for clinker manufacture, but the transportation cost outweighs the economic benefit of using the slag. Additionally, the remaining lime content means that the LFS could not be used for brick manufacture. Clinker grinders were offered the slag, but found that tiny steel particles were still present in the powder, possibly due to the metal particles being coated with LFS. The company is now planning a 1.5Mt EAF melt shop, and is now considering its options for the resultant slag.
Desert in the desert
After the first day of the conference, delegates enjoyed a dinner on the edge of the sandy Arabian desert, including some delicious sweet deserts and a spectacular fire-show (pictured below). The Global Slag Awards were presented, including the ‘slag personality of the year’ awards, which went to Arusha Ahmed Khan of Cemcoa, to Anil Bhadsavle of WALAN Specialty Construction Products, to Niklas Törnkvist of Magsort and to Charles Ochola of the US National Slag Association. JSW Steel and JSW Cement won ‘slag product producer of the year,’ Magsort won for equipment supplier of the year, the ArcellorMittal-Nippon Steel India JV won plant of the year for the Hazira plant in Gujarat, Ecocem won product of the year for ACT (see below), and Saudi Ready Mix Concrete won for slag user of the year. CarbiCrete won the ‘technical innovation’ award (see also below).
Second day
Arunachala Sadangi of Nuvoco Vistas Corporation gave the first presentation on the second day, giving a ‘deep dive’ into beneficiation technology for the improvement of reactivity of LD slags, through reducing its iron content, increasing its glass content and improving its basicity factor. Wet and dry magnetic separation, froth flotation, tabling, a spiral concentrator, enhanced gravity separation, chemical leaching and calcination were all tested. Arunachala concluded that enhanced gravity separation is a suitable technology to improve reactivity, and that the processed LD slag can substitute up to 8% of BF slag.
Kelly Cook of Edw. C. Levy Co. gave a two-part presentation, with the first part giving details of a seven-year case study of the use of steel slag in a heavily-used concrete pad. After nearly a decade of hard industrial use, the pad is still in good shape. In the second part, Kelly asked whether hexavalent chromium is really present in slags, or if it is present only as an experimental relict. Kelly and her colleagues discovered that, on the contrary, steel slag tends to transform any hexavalent chromium (for example added into the sample) into trivalent chromium. Most research is urgently required on this vital topic.
David Algermissen of the FEhS (Institut für Baustoff-Forschung) spoke about the slags that will be produced from the new DRI furnaces. Lime will need to be added to DRI-smelter slags to reduce viscosity to allow them to be handled and further processed. Another option is for DRI iron to be added into an EAF along with scrap steel, but again, viscosity can be a problem. In this case, a secondary slag treatment (reheating in a separate furnace) is possible, or reducing agents might be added during tapping. David gave some details of EAF slag granulation tests, and announced that a full-scale EAF slag granulator will be built in Germany in the next three years. He concluded that decarbonisation of the steel industry will lead to decreasing amounts of blast furnace slag, but the ‘new’ slags will have hydraulic properties if treated correctly.
Volkert Feldrappe of the FEhS next spoke about the use of steel slag in concrete, concluding that if it is to be used, then its free lime content must be low: EAF and DRI-EAF slags (and copper slag) will normally have sufficient soundness, while BOF slag will need to be treated to minimise free lime content. Steel-slag-based readymix concrete has been made in an industrial trial, with excellent performance, showing that heavy metals are bound in the concrete matrix with no significant releases.
Following a popular speed networking session, Andreas Neumann of the German Lithium Institute spoke about the use of iron silicate fines (ISF) from copper slag, and about leached spodumene concentrate (LSC). ISF is somewhat similar in composition to EAF slag, and can be processed by extracting magnetic (Fe-rich) mineral phases, with the remaining non-magnetic iron silicate available to fix CO2 in a solid compound, or potentially to form highly reactive cementitious phases. Lithium can be leached from the hard rock mineral spodumene, but this leaves 96% behind as LSC. However, the LSC has a similar chemical composition to flyash, with no hazardous components, and has pozzolanic properties.
Pithchai Sivakumar of Aurubis, a company with a series of copper smelters throughout Europe, next spoke about the iron silicates generated as a by-product, to the tune of up to around 2Mt per year. The artificial minerals can be used as abrasives, as an alternative raw material for clinker production, for road and landfill construction, for soil stabilisation and for specialist concretes. Some of the minerals produced by Aurubis also have hydraulic properties.
Ryan Bourns of Carbon Upcycling explained his company’s approach to carbon sequestration. A material with adequate CaO and/or MgO content is first ground to increase its active surface area, and is then exposed to CO2 which binds to the mineral particles in a patented process. BOF and EAF slags can sequester up to 20% by weight of CO2, and this enhances the hydraulic activity of both slag types. Additionally, the formation of carbonate minerals can reduce the leaching of heavy metals. The company is now developing two industrial-scale projects at cement plants; in Cemex Rugy in the UK, and at CRH-Ashgrove’s plant in Mississauga, Canada.
Kenneth Lerner of CarbiCrete started by boldly stating that his company has developed a cement-free concrete. Steel slag is cured in a chamber using by-product CO2 to form concrete masonry units (CMUs), resulting in permanent CO2 sequestration.
John Reddy from Ecocem gave the penultimate presentation at the conference, explaining the company’s ACT product. Overall, the company has a production capacity of 2.5Mt, from its four plants in France, the Netherlands and in Ireland. Ecocem has launched a highly specified product, ‘Ecocem Ultra,’ that claims a CO2 emission of only 80kg CO2/t of cement. Furthermore Ecocem’s ACT product has a carbon footprint of around 180kg CO2/t. ACT is composed of 20% Portland clinker, 30% SCMs (BOF slags) and up to 50% ground limestone, and some additives. The product can essentially be produced in conventional plants, and is used in the same fashion as ‘traditional’ cements and concretes. It is expected to be more widely available - in Europe at least - from 2025.
Ali Abdelhaq, supply chain and procurement manager at the National Cement Factory, Abu Dhabi, and his colleague Balasubramaniam, QC manager, introduced the business, which was visited the next day for the event’s second field trip (pictured below during the visit). NCF is a subsidiary of Ittihad International Investment, a diversified conglomerate. NCF uses two ball mills to grind imported GBFS, with a capacity of 3Mt per year. The company’s cement products are present in practically all of the prestige construction projects undertaken in Abu Dhabi and the UAE, as well as being exported throughout the GCC and further afield. Since 2011 the NCF has introduced a number of well-branded slag-based cementitious products onto the market, including AlphaCem (ready-to-use) and AlbaCem (white). The company evaluated more than 30 different sources of GBFS and continually re-evaluates its procurement strategies in the light of market, seasonal and technical changes. The company is in the process of setting up a processing unit for Ladle Furnace (LF) slag. The addition of gypsum into the LF slag improves the workability when used as a concrete additive.
Discussions and prizes
At the end of the programme, delegates divided into two groups to discuss the situation of global slag markets, and into a separate technical group, and discussion in both was described as ‘lively.’
Delegates subsequently gathered for a farewell party, during which the prizes for best presentation were awarded (as voted by the delegates). David Algermissen of the FEhS was third for his paper on DRI slags; Arusha Ahmed Khan was second for her paper on slag markets in Asia; and Kelly Cook of Edw. C. Levy Co. was first for her paper on use of steel slags and on slag characterisation.
Conclusions
After the success of the first post-Covid Global Slag Conference, in Düsseldorf in 2023, delegates voiced their preference to take place in Dubai in 2024. Their intuition that the event would bring great interest and participation from Asia-based delegates was amply bourne-out by the very large number of delegates attending the event in the Middle East.
The event was strongly praised for its technical content, for its smooth organisation and for its excellent networking opportunities.