Jan Eisbacher-Lubensky, Montanuniversität Leoben , Austria

Co-Author:
Christina Brus, voestalpine Stahl Donawitz GmbH
Stefan Wegscheider, voestalpine Stahl Donawitz GmbH
Christian Weiß, Montanuniversität Leoben

Abstract:
In the sintering of iron ores, the chemical composition and the physical properties of coke breeze has a significant effect on the sinter process and the sinter quality. This paper is focused on the influence of coke breeze from different deposits and coking plants respectively, on the sinter process in particular on the off gas composition and the sinter quality. Laboratory-scale sinter feed mixtures with various sorts of coke breeze are produced, whereby the particle size distribution of the investigated coke breeze is constant as well as the coke breeze content with respect to the fixed carbon content. The small scale sinter experiments are performed in cylindrical packings of sinter mix. During the sintering the emissions of CO, CO2, NOx and SO2 in the off gas are monitored, as well as specific sintering parameters e.g. the sinter yield and strength. The results of the off-gas analysis are compared with the chemical elemental analysis of the coke breeze. The investigations demonstrate that a high carbon content of the coke breeze leads to a higher pressure loss across the sinter bed, thus to a shorter sintering time and correspondingly to higher productivity. Changes in the nitrogen concentration in the coke breeze cause significant NOx variations in the off gas. As expected, the total sulfur in the off gas cannot be entirely attributed to the coke breeze. The findings obtained on a laboratory scale enable a coke breeze characterization close to an industrial sinter belt, demonstrating the expected process parameters.

Johan Martinsson, Swerim AB, Sweden

Co-Author:
Niklas Kojola, Hybrit Development AB
Oscar Hessling, Swerim AB

Abstract:
In view of transforming the heavily fossil-dependent iron and steel production into a fossil-free hydrogen-based production, the iron ore pellet could be modified to better suit the fossil-free iron and steel production, including the whole value chain. Considering the higher production cost associated with green hydrogen, the pellet could be optimized to save both material and energy costs during the melting and refining processes of the hydrogen direct reduced iron (H-DRI). At the same time, the modified pellet must keep sufficient mechanical properties as well as reduction properties. A preliminary study is therefore conducted, where the effect of varying CaO/SiO2-ratio was studied with regards to mechanical properties of the pellet, the reduction rate, as well as the dephosphorization ability (wt% P in iron) of the resulting autogenous slag. For this purpose, pellets with three different CaO/SiO2-ratios were studied, ranging from 0.8-1.4. In addition, two iron ore discs were made to broaden the CaO/SiO2-ratio range from 0.2 to 2.4 for the dephosphorization study. The three pellets were supplied by LKAB. Cold compression tests were made to determine the mechanical property. A high temperature resistance furnace was then employed to both follow the reduction of the iron ore using 100% hydrogen, and for melting the H-DRI to study the dephosphorization. While the reduction rate and mechanical properties did not vary significantly within the studied CaO/SiO2-ratio range, it was found that small differences in basicity in the autogenous slag could affect the dephosphorization significantly. The present work therefore finds it highly possible to optimize an iron ore pellet to save material and energy costs during the melting and phosphorus refining.

Maycon Athayde, Minerai de fer Quebec, Canada

Co-Author:
François Lavoie, Champion Iron
Josiane Caron, Quebec Iron Ore

Abstract:
Cold bonding pellet can turn into and important process in the ironmaking industry, eliminating carbon intensive process. However, this route presents high-temperature metallurgical challenges due the behavior in the blast furnace process. The ability of the material to maintain its strength and structure and resist degradation is crucial for producing high-quality h-CBP. In the last years, Champion Iron, a high-grade iron ore concentrate producer in Quebec, Canada have been developing a solution to supply to the ironmaking industry. Previous technologies focused on either organic or inorganic binder systems. A hybrid inorganic-organic binder was formulated, to overcome the weaknesses of the other. Unlike cementitious binders, no thermal conversion is occurring around 750°C, leaving much more leeway to maintain cohesion up to the cohesive zone. Organic portion of the binder provides bonding with both the iron oxides and the inorganic binder, to give the required physical properties. Additionally, the organic content aids the manufacturing process and aids stability, when in the unhardened phase. The 10 m drop test results of 86.9% -6.3 mm and 2.0 % -0.5 mm are slightly below the range of seaborne trade pellets values of 92.4 %-6.3mm and 1.5 %-0.5mm. The reducibility of 0.67 %O2/min is higher traded acid pellets value for BF (0.4-0.6 %O2/min). In this work a modified BRASS test is presented to better characterise the behavior of the h-CBP’s in the non-isothermal blast furnaces. Also, the test was interrupted in different zone to evaluate the progression of the reaction. The results presented also satisfactory reduction rate at the end of thermal reserve zone, and lower fine generation as compared with traded pellet. Champion Iron has been successfully designing a new concept that supports decarbonized hot metal production from a blast furnace with a stable contribution to the ferrous burden, like a traditional product.

Tobias Stefan, Métal 7 inc., Canada

Co-Author:
Steve Beaudin, Métal 7 inc.
Alexandre Goncalves Andrade, Métal 7 inc.

Abstract:
The iron and steel industry is one of the largest industrial emitters of Greenhouse-gas emissions. Most companies are currently undertaking unprecedented steps to transform their production from the traditional blast furnace route to DRI-EAF based steelmaking using hydrogen. At the same time, the required raw material qualities become more and more scarce. Consequently, the key input material for iron making will gradually shift to pellets. In anticipation of a growing demand, more pellet plants are expected to be built in the coming years We would like to discuss the possibilities to decarbonize this important part of the value chain and the possibilities to impact the downstream reduction processes. Up to 20% on energy savings in the pelletizing plants are possible by the correct combination of equipments and technolgoies. In addition, fired pellet quality can be positively influenced by green pellets quality, shape, homogeneous size distribution and reducibility. All those parameters can help save significant amounts of reductant and heating energy in the downstream processes leading to a multiplication of direct CO2 savings.

Guylaine Laforest, Corem, Canada

Co-Author:
Mathieu Dubé, Corem

Abstract:
The global context of action against climate change brought the iron ore producers and steelmakers to engage in ambitious plan for GHG reduction. The direct reduction process is part of numerous steelmaker’s GHG reduction plans consequently this topic is increasingly studied - especially cases where green hydrogen would be used. To ensure that various iron ore products will be performing adequately in either typical or future alternative DR reduction processes, a test evaluating readily their quality, under industrial representative conditions, should be available. This paper presents an updated laboratory scale test method allowing to study direct reduction of iron ore products under conditions close to industrial scale. The updated test allows the use of simulations as input conditions, is non-isothermal, allows for changes in gas concentrations and includes less typical species such as water vapor and CH4. The updated test method follows the impact of direct reduction on pellet performance such as reducibility, metallization, fines generation, pellet deformation, clustering, microstructure, and carbon pick-up.

Suneeti Purohit, Swinburne University of Technology, Australia

Co-Author:
Mark Pownceby, Commonwealth Scientific and Industrial Research Organisation
Akbar Rhamdhani, Swinburne University of Technology
Isis Ignacio, Swinburne University of Technology
Geoffrey Brooks, Swinburne University of Technology

Abstract:
Magnetite ores have the significant advantage of being able to be easily concentrated via magnetic separation, which is now becoming even more important as there is general shift towards DRI processes away from Blast Furnace ironmaking. For many DRI processes, any gangue in the ore is retained in the product, which is expensive to remove via electric melting, so minimising gangue in the ore is an economic priority. In the current ironmaking technologies, it is common to prepare magnetite ores for processing by firstly oxidising to hematite during pelletisation and sintering. This oxidation is carried to improve the reducibility of the iron ore for the subsequent ironmaking process. This improvement in the kinetics comes at a cost in terms of CO2 generation and/or consumption of Hydrogen (an expensive reductant). It is estimated that up to 130 kg of CO2 could be saved by not oxidising magnetite if the issue of reducibility could be addressed. Researchers at Swinburne University of Technology, in collaboration with CSIRO, has been studying how to improve the reducibility of magnetite ore by combining magnetite with lime and measuring the subsequent physical properties and reducibility. Lime is required in the steelmaking process, so introducing lime in the agglomeration step should not necessarily add cost. Substantial testing under laboratory conditions of different combination of magnetite with lime and other gangue oxides (alumina and silica) to form both pellets and sinter have shown that addition of lime (up to 7 wt.%) can significantly increase the reducibility of magnetite without sacrificing important mechanical properties required for subsequent ironmaking operations. Studies using Hydrogen as a reductant, have come to similar conclusions. This paper will summarise the key findings of this work and explore how these findings could be commercially exploited.

Alexandre GonÇalves Andrade, Métal 7 inc., Canada

Co-Author:
Alexandre Goncalvez Andrade, Métal 7 inc.
Steve Beaudin, Métal 7 inc.
Gaetan Lavoie, ArcelorMittal Mining Canada

Abstract:
The roller screening process plays a crucial role in determining the efficiency of the overall pelletizing operation. The screening efficiency directly impacts the pellet bed permeability in the induration furnace, which in turn affects its performance. The segregation concept is a recent innovation in the industry that has proven to increase productivity and quality of fired pellets, while also reducing energy consumption. The implementation of this concept can lead to significant financial benefits, but also turn out as an efficient way to help pelletizing plants to reduce their carbon footprint. The paper will highlight the principles of these technologies and present its real operational performance compared to a typical screening equipment.

Mohammed Liaket Ali, German Aerospace Center, Germany

Co-Author:
Uwe Riedel, German Aerospace Center
Quentin Fradet, German Aerospace Center

Abstract:
Full-fledged computational modeling of Direct Reduction (DR) reactors encompasses single pellets models and the step-wise scaling-up to industrial-scale reactors. The specific focus lies here on scale-up from a single iron ore pellet to a fixed-bed reactor model. However, this process poses several challenges like, a) Synthetic packed-bed structures need to be generated instead of a realistic image-based method due to the high cost, b) Good quality mesh for multi-pellet fixed bed is difficult to generate and c) Scaling up to a CFD environment is cost-intensive. Furthermore, the correct modeling of transport and kinetics-related processes for a single pellet is a prerequisite for a meaningful scale-up. This has not yet been demonstrated. In this work, the chemistry and transport data for the reduction of single iron oxide pellets with H2 gas, obtained from a previously developed 1D solid porous model will be used. The purposes of this article are 1) Proposing a CFD model that reproduces single pellet reduction experiments with H2 gas for wide experimental conditions in a 3D-CFD environment. 2) Computationally generating a random packing of 212 industrial pellets (0.5 kg) by applying the discrete element method (DEM) to simulate a lab-scale fixed-bed reactor. 3) Creating a 3D domain, based on the particle position data from the previous step and meshing the pellets and the voids among them in different refinements. 4) Reproducing a multi-pellet fixed-bed experiment with pure H2 from literature. 5) Investigating the effects of temperature variations in the bed. In this way, the concept of scaling up to multi-pellet fixed bed model simulation with H2 will be demonstrated successfully.

Yul Hong, Hyundai Steel Co., Korea, Republic of

Co-Author:
Yun Mo Lee, Hyundai Steel Co.
Byong Chul Kim, Hyundai Steel Co.

Abstract:
Suitable quality of sintered ore is a crucial factor for stable blast furnace process. However, it is difficult to predict various properties of sintered ore by identifying characteristics of blending ores such as ore size and chemical composition due to its complex reaction mechanism. Sintered ore is generated by assimilation process of granule particles composed of adhering fines and nuclei ores and its reactivity is changed by physical and chemical properties of iron ores. Especially, assimilation between coarse ores and fines is able to influence the sinter bonding strength. Therefore, this study aims to clarify influencing factors on assimilation process and identify correlation between sinter bonding strength and characteristics of coarse ore. To simulate sintering, pseudo particles were granulated with coarse ore (1-3 mm) and adhering fines which form primary melt and then sintered at 1623 K. The simplified Tumbler Index test (TI) was conducted to assess bonding strength of sintered ore particles. Iron ore Reactivity Indices (IRI) were obtained by evaluating TI values of 11 kinds of iron ore brands, respectively. As a result, physico-chemical properties of coarse ores such as gangue, LOI (Loss On Ignition) content and melting point influenced distinct assimilation properties. Coarse ore brand that undergoes intense assimilation reaction has higher IRI value and this phenomenon causes improving sinter bonding strength. Considering the association between Iron Blending ore Reactivity Index (IBRI) and quality of sintered ore generated in the sinter plant, we figured out that higher IBRI increases Shatter Index (SI) of sintered ore. This result shows that not only the comparison of the degree of iron ore assimilation reaction is able to rank each iron ore brands, but also it could predict quality of sintered ore dependent on IBRI.

Bárbara Dornelas, CRM Group, Belgium

Co-Author:
Clément Polato, ArcelorMittal R&D France
Maria Pacheco, Tata Steel Ltd
Laurent Fraiking, CRM Group
Clément Polato, ArcelorMittal R&D France
Maria Pacheco, Tata Steel Ltd
Laurent Fraiking, CRM Group

Abstract:
The dependency to raw materials costs makes the management of sintering plants an everyday challenge to reach the requested sinter quality and production rates while meeting all the environmental constrains (CO2 but also other pollutants like NOx and SOx). The increase of by-products recyclability and recycling rate shall improve both raw materials costs and environmental issues, improving competitiveness and sustainability of European steel industry with limited impact on process KPI’s. SinByOSe RFCS funded project focuses on selective preparation of by-products and solid fuels. The selective preparation of part of the sinter mix is a local countermeasure by means of chemical upgrading (removal of detrimental elements by pre-processing) and by means of particle shaping (pre-granulation). Main solutions investigated in the SinByOSe project consist in : • An innovative pre-processing to increase sinter dust recyclability doing a closed loop washing. The Chlorine abatement obtained is close to 91% and a high %KCl solution is generated, which could be valorized. • Selective pre-granulation of a selected part or whole of the by-products to be recycled through the sinter plant. Current results allows up to 16% productivity increase. • Solid fuel pre-granulation with lime, by intensive mixing, for process and environmental improvement. Results showed an increase of productivity up to 3 tsinter/m².d, a gain of solid fuel of 1 kg/tsinter and constant sinter quality. Environmental results showed a reduction by 15% of SO2 and dust emissions.

Mert Altay, Erdemir, Turkey

Co-Author:
Erdal Ünal, Erdemir
Selda Daldal, Erdemir
Kağan Keler, Erdemir

Abstract:
Iron ore sintering raw blends include various materials such as iron ore, coke, limestone, and recyclable ironmaking and steelmaking byproducts such as return sinter, slags, and sludges. One of these byproducts is basic oxygen furnace (BOF) slag which due to its high calcium and iron content regularly used in sintering by industry. As a recyclable material, it could partially substitute raw materials that include calcium and iron thus could provide sustainability and cost advantages to integrated steel plants. However, due to its impurity content, and physical and phase structure it could also deteriorate process efficiency or product properties. Thus, it is highly beneficial to define the effects of the BOF slag ratio in the raw blend on sintering parameters and sinter product. In this study, pilot scale sintering experiments were conducted with different BOF slag rates in raw blend changing from %0 to %9.25 and changes at the process parameters such as flame front speed, productivity and yield, and product properties such as tumbler index, shatter index and reduction disintegration index are investigated. The result showed that BOF slag usage could increase yield due to its lower loss on ignition compared to limestone however sintering time, productivity, and RDI could worsen with an increase in BOF slag usage rate.

Muhammad Irfan Ahadian Barustan, University of Newcastle, Australia

Co-Author:
Thi Bang Tuyen Nguyen, The University of Newcastle
Evan Copland, The University of Newcastle
Damien O'Dea, BHP Group
Tom Honeyands , The University of Newcastle

Abstract:
The utilization of hydrogen (H2) in blast furnaces is one of the alternatives to reduce greenhouse gas emissions. It was widely known that the addition of H2 can increase the reduction of ferrous burden materials and improve the permeability inside the blast furnace. However, the addition of H2 in a conventional blast furnace, with carbon monoxide (CO) as major reducing gas, might change the reduction degradation behaviour and affect the permeability in the upper part of blast furnace. Previous studies on reduction degradation show that there is still disagreement about the effect of H2 on degradation, especially when the H2 has partially replaced the portion of CO in the reducing gas. Moreover, the extent of degradation also seems to be dependent on H2 content and type of iron ore. Therefore, a study for reduction degradation for a different type of iron ore at different CO and H2 gas mixtures is still required. This study compares the reduction degradation of sinter and lump using a modified reduction degradation test. Various gas mixtures containing CO and H2 are used for the reduction test, including the simulated gas composition for blast furnace with maximum H2 injection. The extent of degradation is compared by the reduction degradation index (RDI) value and microstructure analysis are applied to observe the degradation mechanism.

Tatsuya Kon, Kyushu University, Japan

Co-Author:
Ginichiro Sato, Kyushu University
Ko-ichiro Ohno, Kyushu University

Abstract:
In Japan, ironmaking using blast furnaces is the mainstream, and sintered ore is mainly used as an iron source. Sintered ore is made by sintering the granulated powdery iron ore. The strength of granulates in the sintering process is one of the important factors to improve the gas permeability of sinter bed. In high permeability, productivity of the sintering process increases. In recent years, high-grade iron ore has been depleting, and the usage of low-grade iron ore containing a large amount of gangue mineral such as silica and alumina is increasing. It is expected that the increased gangue mineral affects the strength of the granulate. The purpose of this study is to investigate effect of gangue mineral existence distribution in iron ore particles on the compressive strength of the granules. To evaluate the effect of gangue, coarse and fine powders were prepared by hematite ore containing gangue and pure hematite reagent and 4 types of granulates were prepared as combinations fine/coarse and ore/reagent powders. Theses granulates were produced by wet granulation using a tire type pelletizer. Wet and dry compression strength of granulates were measured by compression tester. From the experimental results, wet compression strengths of granules were similar value and independent of gangue distribution. It is considered that the adhesion force by liquid bridge is dominant in the wet compression strength. On the other hands, the granulates with gangue mineral in fine iron ore powders showed stronger dry compression strengths than other granulates. It is considered the effect of Coulomb force due to electric surface potential difference of hematite and gangue minerals.

Taechang Park, Hyundai Steel R&D Center, Korea, Republic of

Abstract:
The construction of a smart factory platform for digital manufacturing is being promoted by international steel corporations. In this environment, we are implementing AI technologies to replace existing analysis methods and reduce human error. This is referred to as a "smart analysis system" by Hyundai Steel and focuses on the analysis of the raw materials used in ironmaking process as well as the evaluation of the quality of the final product. In this conference, I'd like to share two novel analysis methods for iron ore sinter with deep learning and chemometrics. In the agglomeration process, iron ore sinter is produced for use in blast furnace. Sinter quality and strength are related with the iron ore sinter's mineralogy and microstructure. By using an optical microscope, it is possible to identify the main mineral phases in iron ore sinter, which include hematite, magnetite, calcium-ferrite, and slag. To evaluate quality and operate the ironmaking process in relation to fuel cost optimally, it’s essential to evaluate the fraction for each phase. The phase classification and quantification in the field is currently carried out manually by an analyzer using the naked eye. In this study, a new automated analysis method using deep learning is proposed to replace human inspection for mineral phase fraction. It is notable that the automatic labeling method utilizing clustering analysis has significantly reduced the time required for deep learning-based semantic image segmentation. One of the parameters for the reduction index and reduction degradation index of iron ore sinter is the magnetite ratio. Every four hours in the field, the magnetite content has been measured using the titration method. The existing method, which requires a lot of time, is proposed to be replaced by a new analysis approach that employs Raman spectroscopy and chemometrics.

Sungmo Jung, Pohang University of Science and Technology, Korea, Republic of

Co-Author:
Sung-Wan Kim, POSCO
Seoungkyu Cho, Pohang University of Science and Technology
Leonardo Rocha, Pohang University of Science and Technology

Abstract:
CO2 gas is significantly generated from sinter plants and blast furnaces. It is necessary to reduce the fuel ratio in the sinter mix to decrease the CO2 emission from sinter plants, which will harmfully affect the melt formation and sinter quality consequently. To overcome the loss in the amount of melt, the current study aims to clarify the effect of adding iron ores-based calcium ferrites to the sinter mix on sinter quality and emission of CO2. The addition of calcium ferrites promoted a significant drop in sintering temperature while maintaining the porosity level. The presence of calcium ferrites led to the formation of finer pores, modifying the dominant pore size in the sinter from macro (>100µm) to medium/micropores (<100µm). The amount of SFCA and SFCA-I phases was significantly increased from 9% of the standard sinter to at least 32%. The aforementioned modifications were determinant to the improvement of the physical properties of the sinter, in terms of the degree of reduction and RDI, by at least 24 and 26%, respectively. Due to the decrease in the sintering temperature, the required fuel ratio is expected to decrease by more than 30%, and consequently, the identical reduction ratio has resulted in the emission of CO2. A low-temperature sintering process could be designed by adding calcium ferrites to the sinter mix. Considering the sinter products with a similar porosity level, the refinement of the size of the pores made by adding calcium ferrites might contribute to a better and homogenous percolation of hydrogen gas through the sinter during the reduction process inside the blast furnace, as the hydrogen molecule is known to have a smaller size than the CO molecule. Besides, through the improvement of sinter reducibility and strength, less coke would be required inside the blast furnaces.

Matthew Del Gobbo, Hatch Ltd. , Canada

Co-Author:
Tom Plikas, Hatch Ltd.
Claire Velikonya, McMaster University
Jayant Borana, CRB Canada
Iakov Gordon, Hatch Ltd.
Umesh Shah, Hatch Ltd.
Matthew Del Gobbo, Hatch Ltd.

Abstract:
This paper describes the use of first principles-based approaches to predict the performance of existing and developing assets in the ironmaking flowsheet such as, for example, indurating/pelletizing machines and sinter coolers where the interaction between the solids, gas, and heat flows occurs in a recycled, coupled manner. Quantifying this interaction empirically or through field trials can be challenging. Examples are provided where physics-based models have been developed to simulate the operation of an existing unit and have been validated against field data to ensure they are representative of real-world performance. These approaches are useful for assessing how an existing and developing piece of equipment would respond to a proposed change in the process and operation. These changes can include, for example: re-configuring machine and energy flows for increased solids throughput and/or final pellet quality, reducing fuel consumption per ton of production to improve energy efficiency and reduce carbon-footprint, evaluating the impact of alternative feed type on machine performance, identifying and minimizing air ingress or air leakages, evaluating the feasibility of alternative energy sources such as resistive heating, plasma torches or biomass on performance, and improving overall process control strategies. Outputs from such models include mass and energy balances, solid and gas temperature profiles along the bed height and machine length, extent of heterogeneous reactions in the solids (drying, magnetite oxidation, etc.), interzonal gas flow movements, gas pressure drop prediction and impact on mechanical equipment requirements, refractory & furnace temperatures, burner/combustion performance, air ingress/leakage rates, and other technical parameters associated with machine performance affected by the gas dynamics and solids energy flows. These models are particularly useful as a database generator to improve real-time process control of the equipment.

Kaye Tindale, Rio Tinto plc, United Kingdom

Co-Author:
Pedro Gutemberg, Rio Tinto

Abstract:
The prospect of mining the world class iron deposits on the Simandou Range in the SE of Guinea, is becoming a reality as negotiations on the infrastructure progress with the JV partners. Blocks 3 & 4 of the Simandou deposit held by Rio Tinto Simfer – a joint venture between Rio Tinto, China Iron Ore Holdings (a Chinalco-led consortium of Chinese SoEs) and the Government of Guinea – covers two major deposits named Pic de Fon and Ouéléba, striking roughly 7km each, in a north south direction along the Simandou Range. Work is being undertaken to develop a greater understanding of the geology, genesis and mineralisation of the project to assist in the realisation of the resource and maximisation of value. The increasing geological knowledge presented in this paper will provide an understanding of impacts on the chemistry and physical characteristics of the material mined, processed, agglomerated, and smelted. Teamwork involving geologists, miners, chemists and metallurgists has been conducted to help us understand the impact of the geology on downstream processing requirements to meet the diverse future needs of clients i.e. steelmakers. A comprehensive test programme of work has been developed in order to test and prove Simandou ores as suitable feed-stock for both Blast Furnace (BF) and Direct Reduction (DR) processes. This paper presents promising results obtained at lab scale on Ouéléba ore that show acceptable physical and chemical properties in both sintering and pelletizing for both BF and DR routes. The results of laboratory characterisation and basket tests for the DR shaft process on a sample of Ouéléba DR pellet were also positive, and an assessment of DR pellets based on Pic Du Fon ore ongoing.

Matthias Gabriel, Metso Outotec Oy , Germany

Abstract:
Most forecasts for the global steel industry agree that the steel production will grow until 2050 by another 50%. Scrap smelting and the direct reduction route will account for the lions share of the growth, but the absolute amount of steel produced with the blast furnace route will remain almost the same. This shows that iron ore pelletizing will keep its paramount role to deliver high quality feed material for direct reduction shafts and blast furnaces. Amid the transition of the steel industry towards net-zero carbon, the pelletizing technology must also reduce their own carbon footprint and comply at the same time with the increasing quality requirement for the pellets. Metso Outotec as undisputed leader since the invention of pelletizing technology follows with the NextGen Pelletizing the clear vision to strive for the carbon neutral and fully autonomous pellet plants of the future. For the CO2 reduction the focus is lying on a further increase of the energy efficiency and heat recuperation of the induration process, new combustion concepts as well as the replacement of fossil fuels by means of Hydrogen burners or the substitution of solid fuel by biocarbon. Energy efficiency is also improved by the further implementation of new digital solutions. Metso Outotec’s proven advanced process optimizer Optimus is constantly complemented by new modules like the online measurement and control of the green pellet size, the pellet mix plasticity or the quality of the hardened pellets. All this performance improvements have also significant effects on the process stability and flexibility, the plant productivity and the product quality and finally on the operational cost.

Frédéric van Loo, CRM Group, Belgium

Co-Author:
José Luis Garcia Cimadevilla, ArcelorMittal España
Beate Froehling, BASF SE
Noelia Vega, ArcelorMittal España
Jose Barros Lorenzo, ArcelorMittal Maizières Research
Martin Ciarán, Tata Steel UK Ltd
laurent Fraikin, CRM Group
Yanping Xiao, Tata Steel Nederland Technology B.V

Abstract:
The cold-bonded agglomeration is a method to prepare materials with small particle sizes by turning them into larger pieces (agglomerates) which enable the use of these materials in dedicated processes. Several technologies are available and typically rely on the addition of a binder followed by a compaction step to maximize the contact between the particles of the source material. The suitability of the agglomerates produced for one particular process depends on its propension to maintain a sufficient cohesion between the constitutive particles in a given context : absence of fines generation on transportation belt, maintaining shape during its processing in steelmaking furnaces, … In the ironmaking context, cold-bonded agglomeration could complement high-temperature sintering and pelletizing for the production of the Blast Furnace burden. It does not require a costly and highly CO2 emitting firing/induration and, in the recycling context, could be applied to a larger range of by-products, wastes and other secondary materials. The novelty of the present study is to avoid the use of cement as a binder, removing the detrimental slag addition that the use of cold-bonded agglomerates would have involved. Therefore, the challenge of the partners involved in the project was the production of cement-free cold-bonded agglomerates able to maintain their physical coherence in the conditions of the blast furnace shaft. Two paths were pursed to achieve this result : firstly the use of novel polymeric binders, secondly the selection of the optimal agglomeration technology between vacuum extrusion and roll-press briquetting. The suitability of the samples was tested according to metallurgical standards and in particular the mechanical and reduction strength. We demonstrated that the selected polymeric binder combined with extrusion provides a suitable mechanical resistance at low and high temperatures (upper and lower shaft). The recipe developed becomes a suitable candidate for testing at industrial scale.

Yaowei Yu, Shanghai University, China

Co-Author:
Lixiang Yan, Chongqing Zhenyan Energy Saving and Environmental Protection Technology Co., Ltd.,
Huiting Chen, Shanghai University
Yonggang Zang, Guizhou University
Yuandong Xiong, Shanghai University
Ying Li, Shanghai University

Abstract:
Return fines of sinter (return fines) is used to prepare cold-bonded briquette (CBB). The powder generation rate, compressive strength, reduction disintegration index (RDI) of RDI+3.15 and compressive strength after RDI experiment of CBB are higher than that of sinter. For microscopic morphologies after RDI experiment, cracks initiate in the area of the return fines but don’t propagate through the whole matrix of CBB. Reduction index (RI) of CBB is lower than that of sinter, conversely, the compressive strength of CBB after RI experiment is higher than that of sinter. The CBB has been successfully utilized in the blast furnaces in northwest China, thus replacing 5-15% of sinter.

Awadh Kishor Gupta, Tata Steel Ltd , India

Co-Author:
Debaprasad Chakraborty, Tata Steel Ltd
Vipul Mohan Koranne, Tata Steel Ltd
M. Ramesh Kannan, Tata Steel Ltd

Abstract:
In an integrated steel plant, each process in iron and steel making value chain generates some revert materials in the form of LD sludge, LD slag, ESP dust, Flue dust etc. These materials cannot be thrown out easily as they contain many valuable components – Fe, CaO, SiO2, Carbon etc. Also, nowadays due to stringent environmental laws – outside dumping is not feasible. So, in these scenarios recycling these materials become an inevitable process. Sintering being a versatile agglomeration process has potential to accommodate these revert materials. But utilization of these materials possess challenges as some of them contain harmful elements as such Phosphorus, Zinc & Alkali. These elements limit their usage in sintering, but with proper planning consistency in the consumption of revert materials can be maintained without disturbing the process. At different locations of Tata Steel, consumption of solid waste varies from 60 to 120 kg/tSn. Cold Briquetting, Micro Pelletizing, Online pile making model, Phosphorus management framework to maximize LD Slag consumption, Separate conveyor system and some other modifications in the system enabled to maintain the consistency of supply & quality of revert materials. In addition, Zinc balancing from SP to BF enabled at Meramandali to optimize the consumption of zinc-based materials.

Yakov Gordon, Hatch Ltd., Canada

Co-Author:
Erick Bubniak, DIPROINDUCA  
Jose Senra, Diproinduca Canada Limited
Takshi Sachdeva, Hatch Ltd.

Abstract:
To decrease the environmental impact and increase the value of the by-products produced in the steel industry, recycling of by-products is imperative. This paper identifies three technologies as potential solutions to process low-grade feed as well as strategies to decarbonize these technologies. Oxycup process, Tecnored process and SL/RN Xtra are the three technologies being discussed. The raw materials targeted include fines, sludge material and mill scale. Since decarbonization of the steel industry is critical to meet the 2050 goal Sustainable Development Scenario (SDS) of limiting the rise in global temperature to 1.5 ֯C, a transition of these technologies to H¬ydrogen gas or Biomass as a reductant is also looked at. This paper summarizes the raw material specifications, capital cost, operating cost, environmental regulations and preliminary risks for each of the listed technologies.