Dennis Fischer, D.A.R. Metall AG, Germany

Co-Author:
Felix Kaiser, RWTH Aachen University
Tim Reichel, RWTH Aachen University
Vladimir Vakulchuk , D.A.R. Metall AG
Pioh Cho, Genco Co. Ltd.
Herbert Pfeifer, RWTH Aachen University

Abstract:
The steel industry produces with approx. 1,7 t Greenhouse Gas (GHG) emissions per 1 t crude steel around 10 % of all GHG-emissions worldwide. Thus, a transformation towards green steel production by replacing fossil- or carbon-based energy supply as well as feedstock by alternative resources, like renewable energy and hydrogen gas, is inevitable. However, this transformation is facing challenges since it requires significant technological changes and developments, which need expensive investments and will take around 10 to 15 years until they are completely implemented. To reduce the GHG-emissions already during this transition phase it is essential to modify individual processing steps and materials. Modifications in these process sections can be realised in short time and require low investments but can have a high impact on the reduction of GHG-emissions. Moreover, when the perspective of producing GHG-emissions is expanded beyond the borders of a local production facility onto the supply chain of input materials for steel production processes, there is an additional high potential reducing GHG-emissions. For instance, the replacement of natural resources by alternative input material with a low carbon footprint (CFP), like recycled or secondary raw material, will support lowering the GHG-emissions as well as conservation of resources. This contribution presents three possibilities to lower the GHG-emissions: The substitution of fossil coal by recycled plastic waste with a low CFP, utilization of recycled aluminium granules with a low CFP in combination with an efficient deoxidation injection method as well as innovative refractory materials, which does not contain carbon nor cement and show a higher durability in comparison to usual material. Based on various use cases within steel production considering blast furnace and electric arc furnace routes, the emission savings of the different solutions are presented.

Robert Claußnitzer, AKW Apparate + Verfahren GmbH, Germany

Abstract:
Almost all the iron and steel manufactured in the world is made from pig iron produced by the blast furnace process (BF). However, the dust and especially the sludge generated during the process, do constitute a great challenge for the improvement of the overall sustainability of this highly material and energy intensive industry. During the production of pig iron in blast furnace, a Zn- and Pb-containing sludge is generated in the exhaust air cleaning system. More than 50 % of the mass input becomes outputs in form of off-gas and solid wastes/by-products. This toxic waste can be landfilled after dewatering and pretreatment, which is very costly. The sludge particles contain large amounts of Fe and C that could be recycled in the furnace. However, the Zn content of the sludge is high, and the Zn input to the blast furnace must be limited. There are no standard processing concepts for a BF-sludge treatment plant. The process design and plant arrangement will primarily depend on the nature of the feed sludge and therefore will be based on analysis and pilot test work that is being performed in AKW Equipment + Process Design technical laboratory. On basis of the test results, the suitable and customized process solution will be developed, discussed and later on engineered and executed by AKW Equipment + Process Design. This unique process concept is presented in the following paper: multi-stages hydrocycloning, combined with thickening and filter pressing. Key Words Blast Furnace Sludge, Zn-reduction, Hydrocyclones, Thickeners, Filter Press,

YongWoo Kim, Chosun University, Korea, Republic of

Co-Author:
Sun–Joong Kim, Chosun University

Abstract:
The consumption amount of plastic has increased over the past. Generally, the waste plastics are landfilled or incinerated, which caused environmental problems. Waste polymers, whose main components are carbon and hydrogen, partially replace coke as a carbon source in the EAF process and have the potential for savings of electricity and carbon resources. It is necessary to effectively utilize the waste polymer as a reducing agent by comparing the various properties of waste polymer with those of pure plastics (PE, PP, and PS). In this study, the effect of waste polymers addition on the reduction behaviors of iron-containing by-products was conducted. In addition, the metallurgical properties of the pure polymers and waste polymer were investigated by FT-IR, DSC, and pyrolysis analysis for by-product gas during the reduction reaction.

Manuel Mosconi, Tenaris S.A., Italy

Co-Author:
Cesare Giavani, Tenova S.p.A.
Fabio Melloni, Tenova S.p.A.
Enrico Malfa, Tenova S.p.A.
Marta Guzzon, Tenova S.p.A.
Filippo Cirilli, Rina Consulting – Centro Sviluppo Materiali S.p.A
Loredana Di Sante, Rina Consulting – Centro Sviluppo Materiali S.p.A
Fabio Praolini, Tenaris S.A.

Abstract:
Plasma Reactor to Recover Valuable Metal and Mineral Fraction from Steelmaking Residues Marta Guzzon, Enrico Malfa, Fabio Melloni, Cesare Giavani, Tenova S.p.A. Fabio Praolini, Manuel Mosconi, Tenaris Dalmine Loredana Di Sante, Filippo Cirilli, RINA CSM The EU production of steel in 2021 was more than 150 million tons: 56% from BF/BOF route and 44% from EAF route. This process produced several million tons of residues containing iron oxide, zinc oxide and other valuable metals. Tenova, according to the mission to develop sustainable solutions for the steelmaking, designed a stand-alone process, that can be operated in EU steel shop, to recover the valuable elements present in the steel making residues contributing to a reduced demand of primary resources in a circular economy approach. In the frame of Horizon EU – REMFRA project, Tenova together with Tenaris Dalmine and RINA- CSM will test at the industrial scale a Plasma Reactor for the recovery of iron oxides from different residues, implementing the use of secondary carbon carrier materials. The Tenova Plasma Reactor is based on plasma technology (electrical arc generated by graphite electrodes) working in reducing atmosphere. This pyrometallurgical process has been selected since it can: • treat a large variety of waste streams: by-products coming from the steel industry (slag, scale, dust, sludge), incinerator ashes, catalyst for vanadium (V, Ni, Mo, Co), Mn-sludge, Ni-dust, Al dross and red mud. • use as reducing agent residuals containing C (i.e. biomass, waste polymers, petro-chemical residues) • accept residual containing Si (ceramic, refractory and glass). In the paper, the status of activities and development of Plasma reactor in the frame of the REMFRA project will be presented.

Winfried Ruhkamp, Loesche GmbH, Germany

Co-Author:
Holger Wulfert, Loesche GmbH
Andreas Jungmann, Cala Aufbereitungstechnik GmbH & Co. KG

Abstract:
The development of recycling processes for the use of material resources from industrial waste products or by-products is becoming more and more important. To this end, comminution processes play a key role in processing the material in such a way that recyclable materials become exposed for subsequent separation processes. It was therefore only a matter of time before LOESCHE GmbH, with its decades of experience in fine comminution processes, became the centre of attention for prospective customers who would like to develop and optimize recycling processes. Worldwide three digit mio. tons of steel slags are being produced yearly. The paper/presentation focuses on the development of a dry grinding process for the metal recovery from stainless steel slags. The first production plant worldwide for the dry processing of stainless steel slags with a vertical roller mill was commissioned in Charleroi/Belgium in 2012. The throughput of the plant is ~ 20 t/h. The ground slag has a fineness of approx. 3500 Blaine. The metal recovery is bigger than 90%, the metal content of the concentrate is between 85 to 95% (recoverable metal bigger than 63µm). In addition, the presentation will highlight further possibilities for slag processing and provide an outlook on future technologies that close the steel production loop and increase sustainability.

Joerg Bollmann, John Cockerill, Germany

Abstract:
Authors: Jörg Bollmann, John Cockerill UVK GmbH, Sergej Faber, John Cockerill UVK GmbH  Eco-friendly Acid Regeneration to help decarbonize the steel industry Acid regeneration systems are to reduce pickling process plants’ fresh acid demands and waste streams in general. With both, environmental protection and operating expenditure having substantially expanded in their importance, total acid regeneration plants based on the fluidized bed (FB) technology became today’s state of the art technology for premium steel suppliers increasingly committed to reducing their environmental footprint. In response to this trend, John Cockerill’s latest FB acid regeneration plants (ARP) come with an innovative and environmentally friendly concept, particularly in terms of emissions and waste energy recovery, along with smart and Industry 4.0 technologies. In combination with a perfectly matched tank farm guaranteeing the efficient management of all consumables, today’s highly automated ARPs allow the effective recycling of close to 100% of the spent acid generated in the steel manufacturing process, all while providing the highest possible process security, throughput, and plant availability. What is more, it is considerably reducing the steel complex’s annual dust and mist emissions and lowering or even eliminating other waste streams.  An eloquent testimony of the of the above, is the world’s largest ARP recently supplied to Chinese steel giant Baowu. It allows Baowu to achieve emissions that are only 1/3 of the very latest stringent Chinese standards. Namely the reduction of its steel plant’s dust emissions by 25 tons and its carbon footprint by a significant 4,800 tons per year. Simplified processes, such as quick-change spray/burner nozzles, our maintenance free venturi, our smart plant control system, or our Air Preheating System reducing fuel consumption and the CO2 footprint by a minimum of 10%, are only some of the many sustainable features that will be presented.

Aintzane Soto, Sidenor Investigación y Desarrollo, Spain

Co-Author:
Ivan Muñoz, 2.0 LCA Consultants
Maren Sollbach, Forschungsgemeinschaft Feuerfest e.V.
Christian Dannert, Forschungsgemeinschaft Feuerfest e.V.
Maria Arostegui, Tecnalia Research and Innovation
Abel Calepastegui, Tecnalia Research and Innovation
David Maza, Sidenor Investigación y Desarrollo

Abstract:
Management of ladle refractory waste in European steelworks currently often lacks systematic and integral solutions, with a great part of it being dumped into landfills in many countries. At the same time steelmakers are worried about ladle refractory costs but the improvements are achieved by partial assumptions or trial and error. A RFCS Circular Economy project, based on a 4R´s model, answers to this situation by combining the reduction of refractory consumption with the reuse, remanufacture and recycle of ladle refractory brick waste. The first scientific approach of the European E-CO-LadleBrick project is based on the Reduction of the refractory waste from ladles by optimising the ladle life. To this aim, a “low cost” 3D laser scanner that integrates the technologies Time-of-Flight and Phase-based has been developed. The information of the ladle refractory remaining thickness, obtained heat by heat in hot conditions, was combined with process variables to develop a prediction model of the ladle useful life and wear rate. A commercial equipment was used in order to generate additional data to feed the prediction model, and analyse the performance of the new 3D laser scanner. The second approach aims to optimize the valorization of worn ladle bricks after their use by means of finding suitable applications and calculating their benefits and restrictions, and implementing a data-based decision mechanism for best valorization in either Reuse, Remanufacture or Recycle. A total of 32 new applications were identified and implemented in two Decision Algorithms (one for magnesia materials and one for alumina based refractory waste) that include information about the optical and technical assessment of the refractories and the economic and environmental impact of the possible applications. LCA and LCC were used throughout the project to determine the environmental and economic benefits associated to this 4R approach.

Bruno Touzo, Calderys Belgium, Belgium

Co-Author:
emmanuelle Henry Lanier, Imerys S.A.
Laurence Canton, Calderys

Abstract:
Sustainability has become an integral part of products and processes. Refractories and other minerals used in the iron and steel manufacturing play an important role and need to bring their contribution to help reduce the environmental impact of the industry. A methodology was developed in Calderys to assess the life cycle of their product, from cradle to gate. It is aligned with the WBCSD framework, consistent with ISO standards and used quantitative and qualitative indicators. This paper will present the methods, some results and how this can help Calderys optimize new products and solutions sustainability.

Alexander Schlemminger, QuantoLux Innovation GmbH, Germany

Abstract:
Make the slag and the steel makes itself. This phrase illustrates the important role of slag in steel making. In particular, the increasing efforts in the direction of resource efficiency lead to an increasing demand for accurate slag work. DRI, alternate fuels and secondary raw materials on all routes lead to the import of more and more undesirable elements into the manufacturing process. On the other hand the composition of the slag was one of the last great unknowns of the steelmaking process (at least in-situ). Various workarounds tried to mitigate this issue more or less successfully. However, workarounds can not meet the ideal solution and they do not solve to the actual problem. For this reason, the confidential_steel_plant_disclosure_in_spring_23 has decided to test the fast slag analysis with laser OES. First in the context of a test setup in the central laboratory. After an adaptation period of approx. 2 months, slag samples are analyzed in daily use within approximately 17 seconds. Including sampling, sample shipment In this way, slag work can be carried out virtually without any waiting time on the basis of precise analysis results. In this way, slag work can be carried out virtually without any waiting time on the basis of precise analysis results. Due to the substantial added value, 2 devices have been purchased in spring 2023. The associated fast and precise adjustment of the slag has been proven to increase the cleanliness of the steel which lead to a reduced scrap rate in the end of the line. Furthermore, the tap-to-tap time in the ladle furnace has been reduced by an average of around 4 minutes, which in turn results in corresponding energy savings and increased yield. All in all, the investment in the fast slag analysis thus paid for itself within 5-6 months.

Nella Janáková, Progres Ekotech, s.r.o., Czech Republic

Co-Author:
Martin Gajdzica, Progres Ekotech, s.r.o.

Abstract:
Reducing CO2 Emissions: Industrialization of the hydrogen reduction technology will take some years and further time will pass by until all blast furnaces worldwide will be substituted by hydrogen technology. A bridging technology EcolBriq® offers tremendous value by reducing CO2 emissions on the regular BF production route partially substituting the iron ore sinter process. Recycling of by-products: Recapturing the valuable elements of by products and reducing landfill quantities is another EcolBriq® application creating a cost advantage. The paper presents a cold technology to produce a low-carbon BF feedstock which can be used to supplement the sintering process of iron ore as it is currently known. The implementation of this production process of BF feedstock results in lower energy consumption compared to the high-temperature process of sintering. Thus, there is a significantly lower carbon footprint. In addition, the technology contributes to efficient re-utilization of by-products from metallurgical processes like scale and fractions of dust and slag. A single production line can be utilized for a wide variety of materials as feedstock with different structures, eg: from powder to lumps, minerals like oxide or metal ships with sizes 0-200 mm. The variety of advantages will be discussed: i. Reduction of CO2 emissions for production of the EcolBriq® feedstock compared to sinter ii. Dust reduction for EcolBriq® compared to sinter plant iii. Maximizing the efficiency of the circular economy in BF operations iv. Reducing energy intensity Two case studies will show the results of briquetting two materials which cannot be recycled in sintering plant. First study is focused on briquetting of fine fraction of desulfurization slag and the second one will discuss recycling of oily scales.

Hubert Breukelman, Tata Steel IJmuiden B.V., Netherlands

Co-Author:
Maria Martinez Pacheco, Tata Steel Nederland Technology B.V

Abstract:
The increasingly high demands on European integrated steelworks in terms of sustainability and circularity necessitate the reduction of Greenhouse gas emissions from fossil sources like coke breeze, and require an increase in use of internal waste streams. In this paper, the effect of iron- and steelmaking by-products on sinter productivity and quality are assessed using sinter pot trials. Furthermore, a selective preparation method, the Composite Agglomeration Process (CAP), was used to improve the process characteristics of carbon-rich by-products. This method entails pre-pelletisation of fine-grained components of the sinter mixture on a balling disc, followed by a secondary mixing with the coarse-grained components. To assess the use of the carbon-rich by-products, sinter pot trials were carried out with low (5-10%) and high (15-20%) total by-product content, using the CAP method and conventional granulation. Process monitoring shows that flame front characteristics are strongly influenced by the addition of high carbon by-products when added using conventional granulation, presumably due to combustion kinetics differing significantly from coke breeze. This effect is also observed in the CAP trials, where further effects are observed due to significant differences in sinter bed permeability. The sinter pot trials clearly show that by The CAP method, the replacement factor for coke breeze can be increased, and deterioration of sinter quality caused by high by-product utilization is reduced.

Laura Mariani, Hatch Ltd. , Canada

Abstract:
Electric arc furnace steelmaking now accounts for nearly a third of global steel production. As decarbonization of the industry is pursued through electrification and hydrogen-based direct reduction schemes, the volume of steel produced in EAFs will increase, as will the volume of slag generated as a by-product. Declining ore grades, limited scrap availability, and increased use of DRI will magnify this issue. Valorization of EAF slags has historically met with limited success and many operations simply stockpile or landfill the hundreds of thousands of tonnes of slag they generate each year. Continuation of these strategies is not sustainable and new waste management strategies must be widely adopted. This paper summarizes the factors that will influence future pathways to valorize EAF slags in the context of the development of a truly sustainable steel industry. An outlook for the future of sustainable EAF slag management is also provided.

Mike Duddek, Ruhr West University of Applied Sciences, Germany

Co-Author:
Saulo H. Freitas Seabra da Rocha, Ruhr West University of Applied Sciences

Abstract:
Electrical scrap, particularly battery-powered tools, contain in most cases alloyed steels. These materials are usually incorporated into devices with many other materials, such as copper, aluminium, or magnetic components, making recycling difficult. In traditional recycling approaches, devices are usually shredded as a whole, and the resulting fine fraction is separated in various process steps. This usually generates mixed-metal scrap, as a wide variety of metals are blended. Because of the shredding process, various materials are mechanically bonded (interlocking), making separation difficult, in particular, the separation of softer metals such as copper and aluminium from harder metals such as steel. With a robotised targeted destructive separation of the electrical devices prior to mechanical shredding, this problem can be avoided, and an alloyed steel fraction can be obtained. Using the example of a cordless screwdriver, the separation of the chuck and gearbox from the rest of the device results in a fraction containing only alloyed steel and plastics, without added copper, aluminium or magnetic components, that can be recycled directly in an electric arc furnace. Such targeted destructive fractionation can increase the value of the material stream of electrical scrap and simplify the recovery of high-quality recycled materials. The process of such robotised targeted destructive fractionation and the achieved material qualities are presented in this paper.

Erika Garitaonandia Areitio, AZTERLAN Metallurgy Research Centre, Spain

Co-Author:
Erika Garitaonandia, AZTERLAN Centro de Investigación Metalúrgica

Abstract:
The thermocline Thermal Energy Storage (TES) systems are core elements to boost renewable energies and to improve the efficiency in energy intensive industries. Among TES technologies, air based packed beds storage system represent a promising option since they allow using low-cost materials. The steel slag, a byproduct from the steel production, represents an interesting option as filler material since it fulfils the criteria established in the International Energy Agency (IEA) for TES material, that consist on being inexpensive, available in large quantity without conflict of use, stable up to 1000 °C, compatible with heat transfer fluids and non-toxic. Preceding works have also revealed suitable thermo-physical and mechanical properties to be used as storage material for sensible heat transfer in packed beds. However, one of the critical aspects often not addressed is the durability of the filler material (slag particles) subjected simultaneously to mechanical and thermal stresses over a large quantity of charging and discharging operations. During cyclic thermal charging and discharging, the slag inside the tank is subjected to heavy loads at high temperatures and undergo thermal expansion and shrinkage, which can lead to individual particle degradation and also damage of the tank. For this purpose, different model approaches and tools are addressed in this paper. Specifically designed test rig is introduced in order to test long-term mechanical stability of the steel slag under thermal and mechanical fatigue. Acknowledgements This work has been supported by LIFE programme of the European Union through the Project LIFE20 CCM/ES/001733 ( (https://www.hi4s-life.eu/)

Paul Trunner, Primetals Technologies Austria, Austria

Co-Author:
Paul Trunner, Primetals Technologies Austria
Julian Glechner, Primetals Technologies Austria

Abstract:
"Transformation of the steel sector is likely to see a large number of new EAF installations in integrated steel works. For these plants requirements in terms of environmental impact are significantly more stringent since plants must stay within the actual environmental performance. Within multiple studies, projects, and investigations Primetals Technologies has developed appropriate solutions to minimize the emissions of these installations in regard of particulate matter, gaseous components, and noise emissions. Typical requirements and challenges of European steel plants will be introduced. High performance off-gas treatment solutions including intelligent sensors as well as control strategies to capture and treat any of these emissions to achieve these requirements will be presented. Besides gaseous or airborne emissions, noise emissions to the surrounding have a major impact on the environmental permitting. Intelligent layout arrangement as well as proper plant operation and noise insulation solutions such as furnace enclosuers or special designed bag filter systems will be introduced based on reference cases. To further reduce carbon footprint and increase energy efficiency of the plant off-gas waste heat recovery is a further element for future proof off-gas treatment systems. Highly efficient waste heat recovery plants with compact layout arrangements for new installations as well as typical waste heat utilization examples are presented. All solutions will be explained on an exemplary reference case of a European steel plant."

Alessandra Negri, Tenova S.p.A., Italy

Abstract:
A. Negri1 1 Tenova S.p.A., Italy Key Words: emission, pollutant, steelmaking, fumes treatment plant, FTP, EAF, electric arc furnace, metallic charge, performance improvement, revamping. Abstract The main goal of fume treatment plants installed after electric arc furnaces have been, till today, to control temperatures, quenching and diluting the primary with the secondary fumes, and to remove dust with electrostatic precipitators or bag filters. Injection of activated carbon in the dust removal equipment often is present as a safety measure for the control of the micro-organics pollutants. Possible future scenarios can require different treatments, to comply on one side with presence of pollutants in the furnace off gas coming with low quality scrap, and on the other side with more stringent environmental requirement referring also to other source of pollution. It is therefore fundamental to identify first which of the above pollutants can be present in the fumes. This depends on the metallic charge melted in the furnace, and on the charging and melting method. Each component may be controlled in different ways: the reactions of oxidation, reduction, absorption and adsorption occur at different conditions, mainly related to a determined temperature window, turbulence and presence of reagents. This underlines the importance of designing a fume treatment plant locating each treatment in the position where it can be performed in the most economical way, e.g. promoting the reactions occurring at correct conditions of temperature and turbulence, avoiding the use of expensive catalyst and reagents as much as possible. In this paper considerations of basic engineering and cost estimation of the implementation of air pollution control known technologies to the electric arc furnace application are carried out.

Cristiano Castagnola, Paul Wurth Italia S.p.A., Italy

Co-Author:
Teresa Annunziata Branca, Scuola superiore di studi universitari e di perfezionamento Sant'Anna
Valentina Colla, Scuola superiore di studi universitari e di perfezionamento Sant'Anna
Alice Petrucciani, Scuola superiore di studi universitari e di perfezionamento Sant'Anna
Antonella Zaccara, Scuola superiore di studi universitari e di perfezionamento Sant'Anna
Ismael Matino, Scuola superiore di studi universitari e di perfezionamento Sant'Anna
Luca Spadoni, Paul Wurth Italia S.p.A.
Lorenzo Micheletti, Paul Wurth Italia S.p.A.

Abstract:
In the framework of European Green Deal, steel companies are facing a deep transformation towards ever more carbon-lean processes. Besides studies focused on direct reduction processes, several research works deal with the decrease of the impact of existing routes, for instance, by decreasing the use of fossil fuels. Effectively, the transition from standard integrated route to a direct reduction-based route requires efforts and time but, considering the climate changes and the environmental issues, it is of extreme importance to reduce urgently the greenhouse gases and hazardous air pollutant emissions. In this way, during the transition, brownfield processes can contribute actively and gradually to the Green Deal. This is the context of this study, which focuses on the investigation and development of a process allowing a further treatment of blast furnace gas for ensuring a reduction of NOx when it is used in hot blast stoves and, in particular, at high temperatures. Pushing hot blast stoves at higher temperatures means obtaining higher temperatures of preheated air to be injected in blast furnaces, decreasing coke demand and, consequently, CO2 emissions. The presented treatment is based on a spray-scrubber whose main aim is the reduction of cyanide compounds in blast furnace gas due to their direct link with NOx emissions. The scrubber also allows chlorides removal by reducing corrosion problems. Auxiliary to the gas washing process, a H2O2-based water treatment was invelstigated to reduce the content of cyanides in the blast furnace gas washing water to allow its recirculation and to make purges suitable for discharges. Different kind of analyses were done to develop the process and prove its effectiveness and potential, including literature and data analyses, development of ad-hoc models for scenario analyses, laboratory tests and optimal design of process and unit operations.

Matteo Tomba, PERT Srl, Italy

Abstract:
The Fume Treatment Plant sizing has to be highly customized. This is a common need both for the iron ore-route production (based on Blast Furnace or Direct Reduced Iron plants) and for the scrap route production (based on the Electric Arc Furnace). The steelmaking equipment characteristics and arrangement, the general site layout, the environmental local regulations and the Best AvailableTechnologies (BAT) for the pollution control have to be taken into account. The final choice implies always the comparison among different solutions regarding the fume capturing, the pollutants abatement devices, the possible energy saving, the cooling equipment and so on. The choices for FTP are also linked to the Water Treatment Plant. Often we are asked to improve the current situation with a revamping activity, where only part the existing plant needs to be modified to meet the increased production requirements or the more stringent environmental limits.

Arndt Wilhelmi, Lechler GmbH, Germany

Abstract:
To design or implement a quenching skid or a gas cleaning system in an off gas clearing system has many factors to be considerate.

Soumi Chattaraj, Tata Steel Ltd, India

Abstract:
Chloride in sinter comes from raw materials including iron ores, reverts, Coke breeze and fluxes. Taking into account the thermo-chemical properties of the chloride compounds, sinter product contains less chloride (~20%), but gets accumulated to a greater extent in the waste gas dust. As the waste gas dust (ESP dust) is reused in the process, progressively chlorine enrichment happens. Literature suggests, the alkaline chloride raises the electric specific resistance of dust surface and thereby decreases the electrostatic precipitator (ESP) performance. With continuous increase in the chloride value of dust, ESP performance deteriorates, thereby increasing the dust content in the stack gas. Chloride level increases with field number of ESP as more finer and more chlorine concentrated dust is captured in the last fields. Alkali –K2O & Na2O follows the same trend: more alkali in the final field as alkali remains mainly with finer dust (Cl remains mostly as alkali chloride). To combat the chloride effect there is a study and a trial taken to lessen chloride input to the system by evacuating the “most concentrated” ESP dust of last field and breaking the enriching chloride cycle. Study shows that weekly or in certain frequency bleeding of the last of field dust for a day will help to reduce the chloride load . Our observations shows with this initiative, there is a significant amount of reduction in dust content in stack gas. To reutilize the dust, cleaning this extracted dust is also carried which shows very promising result.

Tobias Plattner, Primetals Technologies Austria, Austria

Co-Author:
Alexander Fleischanderl, Primetals Technologies Austria
Robert Neuhold, Primetals Technologies Austria

Abstract:
"For a green steel production the environmental requirements are rising and ever stricter regulations by governmental institutions require lowest emission levels and utilization of by-products for existing and greenfield iron- and steelmaking plants. The dry gas cleaning technology (MEROS®) reduces the emissions of dust, SOx, NOx, heavy metals and dioxins from agglomeration plants, like sinter or pelletizing plants, safely below the required emission levels. Such low emission levels are maintained by a multi-component additive injection upstream of a high-performance fabric filter. Residues and by-products arising from the gas treatment are often disposed, leading to consumption of valuable landfilling volume and high cost as such material has to be stored under special conditions to avoid uncontrolled leaching of salts and heavy metals. The innovative by-product leaching process is closely linked to the MEROS plant and minimizes on site the residue volume. After the leaching step, the suspended solid like iron oxide will be utilized to the primary process. The brine will be treated in a series of wastewater treatments steps which are designed as a modular system. These treatments steps ensure the compliance with the most stringent discharge emission limits prior to the release of the clean brine into the sea. As an alternative for plants which are not located close to the sea a desalinization step can be installed and product (salt) can be gained by crystallization. How the MEROS and the Leaching technology can fulfill the environmental targets for a green steel production, shall be illustrated based on the latest results achieved with the MEROS systems installed at a plant in Italy and a Leaching plant, realized downstream a MEROS plant in Japan"

Nicholas Walla, Purdue University Northwest, United States

Co-Author:
Chenn Zhou, Purdue University Northwest
Kurt Johnson, Cleveland-Cliffs Burns Harbor Inc.
Armin Silaen, Purdue University Northwest
Chukwunedum Uzor, Purdue University Northwest
Anurag Karambelkar, Purdue University Northwest

Abstract:
Decarburization of the steel industry emission gases have led to extensive research into the use of hydrogen as a fuel source in many of their operations. Research has shown that burning hydrogen fuel in a reheating furnace may cause higher NOx levels in the flue gases which can be harmful to the environment. Several techniques have been studied to mitigate this effect including staging the hydrogen combustion. This work modeled the application of hydrogen fuel using the staged combustion approach with a robust computational fluid dynamics (CFD) model to investigate the potential to reduce NOx emission. Three scenarios were considered for the investigation. Results from the study show that staging the hydrogen combustion reduced the NOx emissions. However, the average temperature of the furnace was also seen to slightly drop. Staging 17.5% of the combustion air showed the best result with a NOx reduction of 14.5%.