ICSTI-12 A report on the international ironmaking conference

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1 ICSTI-12 A report on the international ironmaking conference The 6th International Congress on the Science and Technology of Ironmaking (ICSTI12) and the 42nd ABM Ironmaking Seminar, along with the13th ABM Iron Ore Symposium, held in Rio de Janiero, Brazil on October 14-18, 212, are reviewed in this article with the emphasis on alternative methods of ironmaking. By Joseph J Poveromo* EVERY three to five years the various iron and steel international technical associations organize the International Congress on the Science and Technology of Ironmaking (ICSTI). Since 1994, the ICSTI venue had moved between Europe, North America and Asia (initially Japan, then China in 29). Brazil has been requesting its turn for some time so finally this sixth ICSTI was held in Rio de Janiero, a fitting venue given Brazil s importance as one of the two leading iron ore producers, as well as having a significant steel industry. The Brazilian Metallurgical Society (ABM) hosted ICSTI12, with cooperation from an International Advisory Committee. The event took place in conjunction with the ABM international ironmaking and iron ore symposia that ABM normally holds every four years. The conference was preceded by well attended seminars on charcoal blast furnace ironmaking and iron ore flotation technology. Overall attendance approached 6 (mainly from Brazil, other Latin America, Asia (China, Japan and Korea)) although it was unfortunate that the world economic problems limited participation from Europe and North America to less than 75, mainly presenters of papers. In total, 271 papers were listed to be presented but there were 45 no shows mainly from China (most probably due to Brazilian Visa issues). The Congress started with a day of plenary sessions covering developments in the various regions of the world and key issues to the industry. The presentations which came from China, Japan, Korea, Europe and NAFTA were comprehensive and informative. The presentation about Brazil mainly covered competitiveness issues and made the valid point that Brazil is not necessarily favoured as a low cost steel producer (due to currency, logistics, coal and gas deficiencies, electrical power costs, permitting issues, etc) and therefore the country s steel expansion should be aimed at the Brazilian (and not export) steel markets. Some key points from other plenary papers are: Europe: Dr Lungen of VDEh presented a comprehensive overview of raw materials and blast furnace (BF) ironmaking. He noted that the sinter strand of ArcelorMittal Bremen achieved a productivity of 53.8t/m 2 /24h during 21. Measures to improve sinter productivity include the pelletising of the mixture (hybrid sinter), new ignition furnaces, abandoning of hot screens, optimising the temperature at lower values and various segregation plate designs for charging the mixture onto the sintering strand including horizontal rakes and the so-called intensified sifting feeder. A key point on emissions from steel plants Reference product Benchmark value Average (EU) Difference [kg CO 2 /t product] [kg CO 2 /t product] (%) Sinter Coke Hot metal EAF carbon steel 61 (285)* 1-39 EAF high alloy steel 98 (356)* *Direct + Indirect emissions Table 1 EU Iron & Steel CO 2 targets vs EU performance was that the EU targets for CO 2 for ironmaking processes are not reasonable, considering that current EU ironmaking already represents top performance, as noted in Table 1 below. China: A comprehensive overview of developments in ironmaking included the trend towards building larger blast furnaces (Fig 1) while developments included universal adoption of coal injection, higher hot blast temperatures, and dry cleaning of BF gas, among others. Coke production in China reached 426Mt in 211; accomplished in 27 sets of +7 meter high batteries and 151 sets of +6 meter batteries while stamp charged capacity has reached 15Mt/y and coke dry quenching capacity is now at 1Mt/y. Both techniques improve coke quality. Sintering capacity has reached 79Mt/y with developments including deep bed sintering, intensive granulation, CAP (composite agglomeration process ie the formation of green balls and high basicity granulates) and heat recovery from lower temperature waste heat. Pellet capacity (Fig 2) is led by grate kiln technology (12Mt/y) followed by shaft furnace sintering (about 8Mt/y) with a small role for straight grate sinter production. Domestic ore production (run of mine) is 1327Mt/y but averaging only 3-32% Fe iron content. The challenges facing the BF sector include resource utilization, environmental control and a need to continually phase out obsolete, ineffi Shaft furnace Number Million ton$ Grate kiln Straight grate Year >3 BF volume, m 3 >5 Fig 1 Increase in Blast furnace volumes in China, 21 vs. 21 Fig 2 Pellet plant capacity by indurating furnace design in China *RMI Global Consulting joe.poveromo@rawmaterialsiron.com Steel Times International March 213

2 Apparent steel consumption, Mt Output of domestic steel products, Mt Price CIF ($/t) Coal for coke Iron ore Exchange rate Exchange rate (j-yen/$) Fig 3 Steel production vs. steel consumption in China, POSCO Pohang Works POSCO Gwangyang Works Hyundai BF1 BF2 BF3 BF4 FNX1 FNX2 BF1 BF2 BF3 BF4 BF5 BF1&2 Inner volume (m 3 ) Mt 1.5Mt Hearth diameter (m) Number of tuyeres Number of tapholes Top pressure (bar.g) PCI (kg/thm) (normal) Table 2 Ironmaking (BF and FINEX) Facilities in South Korea cient capacity. One ominous note is steel overcapacity in China, as indicated in Fig 3. Japan: A major trend in Japan is the enlargement of nearly all BFs and reduce the total number operated. Cost reduction of raw materials is aimed at increased consumption of non coking coals and lower quality iron ore. The challenges facing Japan including aging facilities (this being met by BF hearth life and coke oven facility life extension efforts) and increasing costs of raw materials: iron ore and coking coal (Fig 4). A major effort is aimed at increasing BF productivity: >2.25t/day/m 3, and reducing the total reductant consumption to below 5kg/t iron (coke rate <3kg/t and PCI at 2kg/t). Progress in this at Nippon Steel is shown in Fig 5. Other major efforts include R&D aimed at reducing CO 2 emissions, one example of which within Japan s Scope 21 is the development of a novel coke plant. In addition, a consortium of Japanese steelmakers are researching other means of CO 2 reduction operating within the Course 5 research effort, previously described at ICSTI 9 in Shanghai 1. Table 3 Indian iron making units and capacity (Mt/y) Fig 4 Long term increases in sea borne iron ore and coking coal prices, tially zero in 197 to the present day level > 6Mt/y is shown in Fig 6. The current hot metal production at Posco (including Finex plants) and now Hyundai Steel is shown in Table 2 India It was explained how steel production in India and process diversity (including a large use of electric induction furnaces - EIF) increased sharply following economic liberalization in India in 1991 achieving a steel industry profile as summarised in Table 3. The productivity of Indian blast furnaces is around t/m 3 /day as against the global benchmark of ( t/m 3 /day) and the coke rate is (4-52kg/t as compared to the global benchmark of (35-4kg/t) with PCI rates >15 kg/thm. India s lower productivity is attributable mainly to very high alumina (2-4% in lumps ore and 4-6% in fines on average) in its plentiful domestic ore, and high silica giving higher alumina/silica ratios in the furnace charge. There is also high ash (15-2%) in the BF coke which results in high energy consumption in the coke oven and BF. The high alumina 1 Reference Conference Report 5th ICSTI9 (5th International Congress on the Science and Technology of Ironmaking), October 19-23, 29 Shanghai, China. Plant type Units Capacity BF-BOF Integrated 8 3. EAF integrated (DRI) EIF plant EAF/EOF mini plant Gas based DRI* 3 8. Coal based DRI** Mini BF pig iron* 42 Ferri-Alloy units Total (excl ferroalloy) *Mainly for EAF; **Mainly for EIF NSC average coke ratio (kg/tp) CR Productivity Coke ration decreased dramatically. (Here coke rate include nut coke) Average is reaching less than 32kg/t. Coke ratio of last September was 317kg/t NSC average producticity (t/d/m 3 ) Fig 5 (left) Improvement in blast furnace productivity at NSC and reductant rate over three years Fig 6 Growth of hot metal production in Korea, Crude steel production (Million ton) POSCO Foundation 68 Gwangyang Works 92 Pohang Works 83 Hyundai Steel Dangjin Works FINEX 1 Commercial Plant March 213 Steel Times International Korea This presentation started with a reference to the challenges posed by high raw material prices, as already shown in Fig 4, as Posco had developed its steel industry based on cheap imported raw materials. Korea s dramatic increase in hot metal production from essen

3 Kg coke/t 56 2,995 2, NTMK Severstal ,17 51 Volipetsk Steel Summary fuel rate, kg coke/t 2,131 2,12 1, , ,5 2 1,498 1,5 548 MMK Mechel ZMSK Tula- Uralskaya Chermet Steel Productivity, t/m 3 per day t/m 3 per day Fig 7 BF productivity and coke rate of Russian BFs by company for 211 Fig 8 (below) Location of blast furnace based steel plants in Russia HM ex blast furnace [Mill.t/y] BF 8 6 DRI Fig 9 DRI vs BF ironmaking, DRI production [Mill. t/y] HM ex blast furnace [Mill t/y] BF Corex Finex HM ex Corex/Finex [Mill t/y] Fig 1 Corex/Finex vs BF Ironmaking, ; NTMK 4.7; Mechel 3.7; Ural 2.4; Tula 1.9; others.8. and silica content in the iron ore also results in the formation of a very viscous slag that severely affects BF performance. Therefore, raw material beneficiation is important including an expansion of pelletising capacity to use available ore fines, much of which is stockpiled resulting from calibration of lump ore which has been the preferred charge to Indian BFs. Integrated steel plants have installed stamp charge coke oven batteries to increase the use of medium coking coal and semi soft coals. Russia Prof Kurunov s gave an informative overview of Russian steel production by company including BF productivity, fuel rate (Fig 7), blast temperature and oxygen enrichment. The locations of Russian steel plants are shown in Fig 8 while the hot metal production levels at these plants (Mt/y) in 211 were: NLMK 9.8; MMK 9.5; Severstal 8.8; ZSMK Steel Demand Equity Cliffs IOC AMMC Sinter AHMSA AK Steel EssarAlgoma ArcelorMittal* (3.)* 2.8 SeverstalNAm RG Steel US Steel Export *Included in ArcelorMittal equity supply NAFTA Dr Poveromo (the author of this review) gave an overview of raw materials and ironmaking noting the role of now cheaper natural gas from shale deposits in USA, increasing BF gas injection rates and the return of gas based DRI production (presently under construction by Nucor). As a result, no further expansion of coal based pig iron/hot metal production is foreseen due to the present low gas prices. The iron ore discussion for USA included the pellet supply/demand balance in 211 which showed a demand of 68.9Mt and a surplus of 16.33Mt for export (Table 4). Following the plenary sessions of the first day, the next two days featured parallel sessions (5 to 8 at a time) and poster sessions covering the range of iron ore mining, beneficiation, agglomeration and raw material properties, ironmaking processes, environmental, energy saving and maintenance topics with both invited and submitted papers. Both blast furnace and direct reduction topics were covered. Table 4 NAFTA pellet supply/demand in 211 Mt/y Process Scale-up 1st plant Capacity 1st plant capacity Ramp-up Number Comments Critical Capacity Designed Achieved current years of operating parameter MMtpa MMtpa Max MMtpa units Table 5 Alternate ironmaking technologies scale up, ramp up experience ITmk >2 1 By-weekly basis Inmetco Feed charge capacity IDI Off-gas system capacity Fastmet Feed charge capacity SL/RN multiple Diameter >4.8m Corex Finmet Campaign basis Finex Midrex HYL I operating now HYL III >22 Including 3HYL ZR Primus Feed charge capacity Hismelt >6 Monthly basis. Shutdown The ramp-up period varies from 2 to 5 years, typically of about 3 years March 213 Steel Times International

4 Iron ore Oxygen CO 2 Oxygen Coal Fig 11 HIsarna ironmaking two-stage process This review can only select just a few of the 271 papers scheduled, the choice being those that seemed to offer the greatest impact on the current challenges to iron and steelmaking. New Ironmaking technologies Dr Lungen of VDEh presented the Keynote lecture on ironmaking alternatives to the blast furnace noting the vast number of processes proposed in recent decades: 72 direct reduction processes and 59 smelting reduction processes, of which less than 1 each are still commercially active in some form. The importance of establishing overall material and energy balances in process assessment was emphasized. Although both Corex and the related Finex smelting reduction capacity are growing (over 6Mt in 21) and direct reduced iron (DRI) is now well established (75.1Mt in 211), the dominant position of BF based ironmaking is still apparent producing 199.9Mt in 211 (Figs 9 and 1). The scale advantage of the blast furnace is evident when comparing the technologies with maximum capacities presently reaching 5.3Mt/y for the blast furnace; 2.Mt/y for shaft furnace DRI units such as Midrex, HyL and Energiron; 1.5Mt/y for Corex & Finex;.5Mt/y for rotary hearth furnaces and.3mt/y for rotary kilns. The correct process selection answer for any region or company is dependent upon many factors: Prices and availability of iron ores, ore quality, coking coal availability and cost and the price of import or exported energy from NG, COG, BFG and electric power and ultimately the costs for CO 2 emissions. Experience and risks Hatch presented a highly informative paper as it started with the importance of proceeding through conceptual, laboratory, pilot scale, demonstration plant and commercial phases with rigorous assessment at each stage before proceeding to the next phase. The following questions should be asked to mitigate the risks as the projects evolve: Is there a need for this technology? (market information); Do we have a process? (scientific information); Can we scale up? (engineering information); Are adequate equipment, materials and controls available? (engineering information); and Do we have a viable business? (business information). The importance of defining key milestones involved with the implementation of new tech- XX March 213 Steel Times International Iron nology and rigorously carrying out the required analysis before advancing to the next phase cannot be overemphasised. The history and experiences of developing processes such as Midrex, HyL, Corex, Fastmet, Inmetco, Iron Dynamics, and ITmk2 were presented in detail. The key scale up and ramp up info for these processes is summarized in Table 5. HIsarna Tata Research and HIsmelt jointly outlined this process that can use coal and fine ores directly and therefore does not require coking and ore agglomeration. The HIsarna concept was created by combining the smelt cyclone converter furnace (CCF pre-reduction) technology of (now) Tata Steel with the bath smelting technology of HIsmelt (Rio Tinto). The CCF technology was developed at Tata Steel IJmuiden (by the then Dutch Hoogovens company) with the pre-reduction and melting of fine ores taking place in a smelt cyclone that was extensively tested up to scales of 2t/hour of injected ore. HIsmelt originally started as an ironmaking modification of the bottom-blown KOBM steel converter technology. Ultimately, HIsmelt built and operated a commercial plant that produced over 8t/hour in Kwinana, western Australia. Although this plant has since been closed due to unfavourable market conditions, the core process worked and considerable experience was gained with scale up for this type of smelting reduction vessel. ULCOS (a European consortium for ultra low CO 2 steelmaking) brought these technology streams together in 26-27, leading to an ULCOS-supported pilot plant project at IJmuiden in cooperation with Rio Tinto (HIsmelt) to prove the new process known as HIsarna. The process scheme is shown in Fig 11. Corex and direct reduction In Austria, the then VAI company (now Siemens VAI Metals Technologies) developed an earlier German technology for combined hot metal and DRI production known as Corex. The paper updated present Corex projects at Essar Steel in India and Baosteel in China. Essar commissioned two Corex C-2 plants (1.7Mt/y) in late 211. These Corex plants were originally supplied to Hanbo Steel of S Korea and partly erected in at Asan Bay. Following the bankruptcy of Hanbo Steel, they were bought by Essar in 25 and subsequently relocated to Hazira, India. The high calorific High export gas Low export gas Corex gas for energy energy DRI Fuel dry 94 (kg/t HM ) 77 (kg/t HM ) 55 (kg/t iron ) Additives 265 (kg/t HM ) 185 (kg/t HM ) 16 (kg/t iron ) Oxygen 52 (MW el /t HM ) 455 (MW el /t HM ) 34 (kg/t iron ) Byproduct (MW el /t HM ) +.9 (MW el /t HM ) 1. (t DRI /t HM ) Table 6 Possible Corex plant configurations Table 7 Comparison between charcoal and coke blast furnaces Charcoal BF Coke BF Working Volume (m 3 ) 3 to 55 > 45 Production (kt/y) 2 to 5 >1 Fixed carbon (%) Volatile matter (%) Ash (%) Compressive resist (kg/cm 2 ) 1 to 5 13 to 16 Reductant consumpt (kg/t HM ) 57 to 7 45 to 55 Pulv Coal Injection (kg/t HM ) 1 to 2 1 to 17 Blast temperature (ºC) 6 to 11 1 to 13 Hot metal temp (ºC) 13 to to 155 Sulphur in metal (%).6 to.8.2 to.45 value export gas generated in the Corex plants is used in Midrex modules at Hazira for DRI production and also for various heating purposes within the steel works. The first coupled Corex-DRI plant started up in 2 at Saldahna Steel in South Africa (now ArcelorMittal South Africa) where Corex offgas feeds a Midrex DRI module. The Corex plants at Jindal JSW in India are now being modified to provide feed gas to on-site DRI plants. The range of use of Corex off gas possibilities is shown in Table 6 Modified blast furnace concepts ICSTI 12 included many papers on research efforts to modify the blast furnace process both from an equipment perspective: recycling BF top gas, stack gas injection, oxygen only blast, etc, and from a raw materials perspective: synthetic lump ore and composites of iron ore and coal. One paper on the latter topic included testing at Nippon Steel of a composite of iron ore fines and coal called RCA (Reactive coal agglomerate). Long-term plant trials were conducted at the Oita Works No 2 BF with a maximum use of 54kg/tHM. Carbon consumption was decreased by.36 kgc/thm per 1kgC/tHM of input carbon from RCA. The RCA material had an Fe content of 37%, a carbon content of 21% with about 12% of fluxes, mainly CaO. This material, however, has limited cold and hot strength as compared to fired agglomerates such as pellets and sinter, hence its total consumption is limited to 1% maximum of the charge in modern, large, high performance blast furnaces. Full application of this concept requires furnace modification including a lower shaft height. Laboratory, pilot plant studies Papers on the topic of laboratory and pilot plant studies were highly varied, both geographically and technically. Studies included: Flash Ironmaking Technology: At the University of Utah where a novel approach is being developed under the financial support of the American Iron and Steel Institute. This technology is based on the direct gaseous reduction of iron oxide concentrate in a flash reduction process. This has the potential to reduce energy consumption by 32-57% and lower carbon dioxide emissions by 61-96% compared with the average current blast furnace operation. The process uses gaseous

5 Integrated Coke BF Charcoal BF Independent (charcoal BF) Total charcoal Exported pig Table 8 Brazilian pig iron production by charcoal & coke blast furnaces (Mt/y) Fig 12 Charcoal prices vs pig iron prices Precos (US$/Ton) Preco Carvao Preco Gusa Relacao Preco Carvao/Gusa reducing agents such as natural gas, hydrogen, syngas or a combination of these. It is to be applied to the production of iron as a feed to the steelmaking process or as part of a continuous direct steelmaking process. Cr-Ni pig in a Rotary Hearth: In Cuba, a major existing metallic resource is the by-product of large scale nickel production. Accordingly, a study was undertaken at Nicaro to produce nuggets of pig-iron containing Ni and Cr, using a Rotary Hearth Furnace, which is the most feasible process from the economic, environmental and technical points of view. After magnetic beneficiation, the by-products from Ni production are combined with carbon to produce a green ball for the RHF resulting in pig-iron nuggets containing: Cr 1.88%, Ni.62%, Si.65%, Mn.36%, Co.15% and V.4%. Such pig iron could be used in the production of cast iron alloys rich in Cr and Ni. Reduction of Zn ferrites: At the Catholic University in Rio se Janiero, Prof Abreu and his group are studying the reduction of Zn ferrites by CO-CO 2 gas mixtures; the relevance here is the high Zn content in many steel plant residues such as BOF and EAF dusts. The reduction of Zn in rotary hearth composite materials including such residues could provide an effective way to recover these Zn units while providing Fe units for recycling. Biomass Reduction with sawdust: Researchers at the University of Sao Paulo in Brazil studied the use of biomass (sawdust of different types of wood, as it can be obtained in sawmills) as a substitution for mineral coke. A self-reducing mixture of low grade iron ore (43.5%) and sawdust (56.5%) was processed in an electric rotary kiln where they achieved 99.2% reduction in the production of pig ironcarbon nuggets. Such results could open the way for the direct use of biomass as a reductant for iron ore in a more energy efficient manner. Charcoal based Ironmaking: The venue in Brazil naturally provided the setting for discussion (in both the pre conference seminar and ICSTI 12 Symposia) on charcoal based ironmaking; Brazil is the only country remaining using charcoal blast furnaces, a technology gradually phased out in Europe since the first use of coke by Abraham Darby in England in 179. These sessions covered the entire production chain from forestry and wood carbonisation to produce charcoal, design and operation of charcoal mini blast furnaces including integrated steel production (2.1Mt/y) with charcoal based liquid hot metal production as well as production of merchant pig iron (5.5Mt/y). Such pig production takes place in four regions of Brazil: about 5% is produced in the ore rich Minas Gerais state in the SE of the country, the Iron Quadrangle, with the balance split among the north (Maranhao, Para), the south (Espirito Santo) and the west (Mata Grosso) of the country. However, coke based BF production is the predominant method of iron production in Brazil (25.5Mt/y). The environmental benefits from neutral CO 2 emissions of green steel production from charcoal based pig iron are debatable. Charcoal based ironmaking starts with one hectare of eucalyptus plantation to produce 45t of charcoal that in turn produces 65t of pig iron. The eucalyptus is mainly grown in eucalyptus plantations cut at seven years. However, the soil is spent after two cycles so the renewable claim cannot be justified, and, indeed, some 25% of charcoal is sourced from virgin natural forest. Also, the remaining root stock slowly decays releasing methane, a GHG some 2 times more potent than CO 2. About 1Mt/y of charcoal is produced in Brazil of which 9% is for industrial use dominated by iron production with some consumption from the alloy and cement sectors. The remaining 1% is mainly for residential use. Carbonisation of the wood is conducted in the absence of air at 28 35ºC with the products being solid charcoal and volatile products. The carbonisation kilns range from primitive mounds of bricks to well instrumented steel vessels large enough to drive a truck into. The main differences between charcoal and coke blast furnaces are the charcoal furnace is: Much smaller the largest having a working volume of 568m 3 ; Simplicity with respect to auxiliary equipment, cooling and refractories; Robustness, they are flexibility to burden materials and operating mistakes. Low specific capex as many are Homemade BF. The operating differences between charcoal and coke BFs arise due to the characteristics of charcoal: Higher volume of reductant, lower volume of ore; High reactivity of charcoal that leads to: More intensive Boudouard reaction; (C+CO 2 = 2CO) Higher heating value of BFG (3.8 to 4.2 kj/nm 3 ); Faster decrease in particle size resulting in reduced permeability; Lower residence time iron ore reducibility; Lower RAFT (flame temperature); Internal temperatures cohesive zone: 8ºC. The differences between charcoal and coke based BF production in Brazil are illustrated in Table 7. Charcoal based iron & steel production: Several steel plants: APERAM (ex- Acesita) a stainless steel producer Vallourec & Mannesmann and those of Gerdau at Divinópolis and Barão de Cocais, use iron from charcoal BFs. In addition, there are some EAF plants with on site or nearby charcoal based pig iron production. Under construction by the Ferroeste Group in northern Brazil at Açailândia Maranhao is the AVB (Acos Verdes do Brazil) steel plant. It will produce.5mt/y of long products using the BOF to billet caster route employing liquid hot metal from nearby charcoal BFs. The comparison between Brazil pig iron production before and after the global financial crisis is shown by the comparison between 27 and 211 in Table 8 which indicates close to a fall of one third in charcoal BF production. The market for independent pig iron producers includes Brazilian EAFs and foundries but the strong dependence upon the export market (over 5% to the USA) is apparent in Table 8. The challenges for the independent producers includes the escalation of charcoal prices although pig iron prices have also increased as shown in Fig 12. Looking at a less optimistic scenario one can foresee the following occurrences: falling availability of legally obtained char coal; shrinking of the international pig iron mar ket; low availability of planted forests in Brazil s northern region; traditional major USA pig iron buyers investing in more DRI/HBI production: Nucor, SDI, North Star, Severstal, etc as the price of gas falls in North America. The survivors among Brazilian independent pig iron producers will include those with captive, sustainable forests and charcoal production, iron ore assets and with the potential to expand into steel production as is being done by Ferroeste at AVB Steel. A CD of the Proceedings of The ICSTI 12 can be purchased from ABM. Contact martina@abmbrasil.com.br. March 213 Steel Times International