Energy consumption and CO2 emissions is an ever-present issue for energy intensive industries, such as the steel industry. The work for reducing the environmental impact is a strong interest among the governments in Europe and the 20-20-20 targets, decided by the EU, set the targets for the year 2020 to increase energy efficiency by 20 %, reduce greenhouse gas emissions by 20 %, and increase the use of renewable energy to 20 %. It is therefore important for the steel industry, and other industries, to continuously be working on development of concepts for decreasing the environmental impact, which are also financially viable. This paper presents the work that has been conducted in order to evaluate the potential benefits regarding energy- & cost saving and CO2 mitigation, when recovering and utilizing low temperature waste heat at an integrated steel plant in Sweden, SSAB EMEA Lulea. In order to achieve a holistic overview of the plant a process integration approach is applied to evaluate the effects that occur when applying technologies for waste heat recovery. The results indicate a potential for energy saving of 1.9 %, and a corresponding CO2 mitigation potential of 1.5 %. The calculated payback time for the applied waste heat recovery concepts, which is based on specific methods and economic assumptions, range between 1.5 - 7.0 y. 

In a complex industrial batch processes such as the top-blown BOF steelmaking process, it is a complicated task to monitor and act on the progress of several important control parameters in order to avoid an undesired process event such as "slopping" and to secure a successful batch completion such as a sufficiently low steel phosphorous content. It would, therefore, be of much help to have an automated tool, which simultaneously can interpret a large number of process variables, with the function to warn of any imminent deviation from the normal batch evolution and to predict the batch end result. One way to compute, interpret, and visualize this "batch evolution" is to apply multivariate data analysis (MVDA). At SSAB Europe's steel plant in Luleå, new BOF process control devices are installed with the purpose to investigate the possibility for developing a dynamic system for slopping prediction. A main feature of this system is steelmaking vessel vibration measurements and audiometry to estimate foam height. This paper describes and discusses the usefulness of the MVDA approach for static and dynamic slopping prediction, as well as for end-of-blow phosphorous content prediction. Multivariate data analysis (MVDA) methods have been applied on the top-blown BOF steelmaking process, with the main aim to create industrially applicable static (i.e., prior to blow), as well as dynamic in-blow batch models for predicting the slopping probability. The MVDA approach has also been investigated in regard to in-blow prediction of end-of-blow phosphorous content.

The main production of primy Iron from ore is now made by reduction using fossil reductants, either by producing hot metal in the blast furnace process or as directly reduced iron with natural gas as most common reductant. The climate gas impact would be improved if at least pt of the reductants could be produced from Biomass. One possibility could be to use gasified Biomass to produce DRI (Directly Reduced Iron). This is studied in a cooperative project where LTU, MEFOS, ETC and five industries in the eas forestry & pulp, mining, iron and gas e involved. The investigation is made in four pts where the first one is on the supply of biomass. A lge amount of Biomass has to be delivered into a single site to exchange a lge amount of fossil reductant. Also, forestry by-products should be used as most of the round wood is reserved for other uses. Hvesting, logistics and economics e considered. The second pt is on the gasification of the biomass, where the aim is to use to produce hot gas that can be used directly. Pilot experiments e cried out using oxygen in an entrained flow gasifier. The third pt is on the metallurgical processes, where reduction tests e cried out with gas that can be produced in the gasifier. The limitations of the gas content e studied as well as the effect on DRI. Also the suitability of the DRI product is evaluated. The fourth pt of the project uses process integration to model the whole process chain. The results from the other project pts e used to build the system model. It is then used for technical economic optimization the whole system hvesting- Transport-gasifier-direct reduction-use of DRI. The first use of the system model has been to find the best supply road (hvesting, pretreatment and transport) for a chosen production case The simulations indicated that the supply of residuals is possible but will need material from a lge pt of the north Sweden wood ea, and that a relatively lge amount of gas recirculation is needed. The continuing work is focused on further development of the optimization tool and the use of it for more extensive studies of the trade-off between pameters of metallurgy, gasification and supply. The result can be important for evaluation of future industrial applications. It could also help in understanding the effect of governmental control instruments. The paper will mainly focus on the process integration study.

The closed type DC arc furnace was investigated as a smelt reduction furnace for reducing steelmaking slag, especially molten hot slag. The reduction capability and its characteristics in DC arc furnace were clarified through the experiments of slag reduction in closed type pilot scale DC arc furnace and in open type commercial scale DC arc furnace. For further comprehension of the reaction mechanism flow pattern in slag and metal phases was examined by numerical analysis. Moreover the effectiveness of using hot slag was shown by estimating the heat balance of the typical test operation using cold slag.

Carbothermic reduction of chromite is an important industrial process for extracting chromium from the chromite. To have a better understanding of the effect of iron on the carbothermic reduction of chromite, the reduction of synthetic chromite (FeCr2O4) by graphite with/without the addition of iron powder was investigated in this paper by Thermogravimetric Analysis (TGA) in argon atmosphere. The fractional reduced samples were examined by SEM/EDS and XRD analysis, and the reduction process was thermodynamically and kinetically evaluated. The experimental results show that the iron powder addition enhances the reduction of FeCr2O4 and this effect increases when increased amounts of iron powder are added. This phenomenon is attributed to the in situ dissolution of chromium into the iron and mixed carbide (Cr,Fe)7C3, which can decrease the activity of the nascent chromium formed by the reduction of the FeCr2O4. The experimental results indicate that the reduction of FeCr2O4 with up to 80 wt.% iron powder addition is likely to be a single-step process and the kinetic analysis suggests that the reduction reaction is likely to be either (a) chemical reaction at the surface of FeCr2O4 or (b) diffusional dissolution of the product (FeCr2) into the iron/alloy particles or the mixed control of (a) and (b).

This paper presents a fundamental study on the carbothermic reduction of chromite ore with the addition of mill scale, which forms the basis for designing an alloying precursor, "chromite ore + mill scale + carbon," for direct chromium alloying. The reduction of chromite ore by petroleum coke with or without the addition of mill scale is investigated by Thermogravimetric Analysis (TGA) under non-isothermal conditions (from room temperature to 1823 K) in the argon atmosphere; the fractional reduced samples were characterized by SEM/EDS and XRD analyses. The experimental results show that the mill scale in the alloying mixture is reduced to high active iron first and disseminated around the chromite ore particles; the reduction of chromite ore is enhanced with the addition of mill scale especially at temperatures higher than 1623 K, and the enhancing effect increased with increasing mill scale addition. The enhancing effect is attributed to the presence of molten Fe-C alloy in the vicinity of chromite ore, which can decrease the thermodynamic activity of chromium by having chromium in situ dissolve into the melt. In this paper, the effect of mill scale addition on the reduction of chromite ore is investigated on the samples with three different amounts of mill scale addition (78 wt%, 38 wt%, and 0 for the samples #1b, #2b, and #3b, respectively) by thermogravimetric technique. The fractional reduced samples are characterized by SEM/EDS and XRD analyses. The mechanism of mill scale addition on the reduction of chromite ore is discussed and the industrial implications of the experimental results are also presented. 

An advanced numerical model has been used to diagnose casting practices for a peritectic grade in a Scandinavian steel producer. The model solves the Navier-Stokes equations by use of an interface tracking technique known as the Volume of Fluid (VOF). Furthermore, the model considers heat transfer, solidification and uses Discrete Phase Model to simulate a multiple phase system of steel, slag and argon. As a result, it is possible to predict the metal flow and slag infiltration as well as their influence on the heat flux and solidification under the effect of gas Injection and for transient conditions. Recent improvements to the model include a separation between mould powder and slag film and the consideration of the effect of crystallization on the interfacial resistance for a peritectic mould powder. The casting parameters analysed consist of the casting speed Interlocked with oscillation settings, Submerged Entry Nozzle (SEN) Immersion depths and argon injection flow rates. These practices were optimised by performing parametric studies to evaluate the shell growth, lubrication depth, cooling channel heat flux, etc. The application of the model allows for a prediction of trends and the results provide opportunities for further Improvement in the form of guidelines for the process and enhanced operational windows. The model has been tested under industrial conditions and the results indicate the improvements of the surface quality and process stability can be obtained.

A 2D transient thermo-mechanically coupled axi-symmetric FE model has been implemented and used to predict the temperatures and stresses under cooling of coils. The temperature trajectory as a function of geometrical position in as-coiled steel strip products is affected by several parameters as the: initial temperature inherited from upstream cooling on the Run Out Table (ROT), coil dimensions, strip surface quality, contact conditions and the surrounding environmental conditions etc. The layered structure makes the thermal conductivity anisotropic where the interfacial contact condition depends on the transient stress state caused by thermal and initial effects. The coil cooling rates are for HSLA-steel grades of importance in achieving proper final mechanical properties where too fast temperature drops ceases the precipitation hardening solely diffusional driven. Furthermore is a parameter influence study made revealing process parameter significance. The model has been validated against two full-scale bell furnace trials. A main objective with this model development work was to keep the model fast and accurate applicable on real plant situation and for process controlling.

In the frame of the European Research Fund for Coal and Steel (RFCS programme), in the last 15 years many research and demonstration projects have been carried out on different aspects of EAF technology, aiming at improving the process performance in terms of energy and resource optimisation, flexibility and environmental impact. This effort contributed to the development of a number of technological solutions in terms of process modelling, measurement systems and process control. Within the RFCS programme, in 2014 and 2015 the project "Valorisation and dissemination of EAF technology" (VALEAF) was carried out. This project aimed at analysing and disseminating the most important results of European research projects dealing with the different aspects of EAF technology. The paper will presents the applied methods as well as the achieved results and deliverables of the dissemination work performed in the VALEAF project. It will covers the critical analysis of the results obtained in more than 60 EU funded projects with respect to the main topics of EAF technology. The most important results in these fields were selected for valorisation and dissemination within a series of seminars and workshops, which turned out to be a useful step forward to diffuse and favour the exploitation of the findings, and to provide a clear picture of the actual status of European EAF technology. Finally future industrial targets and requirements for further research activities were identified, and a roadmap for future developments of EAF technology was defined.

Process Integration is a common name for system oriented methods and integrated approaches to complex industrial process plant design. In Process Integration, interactions in the industrial system are taken into account during process design and optimization via their material and energy flows. The use of systematic methodologies is a very effective approach to improve the energy and material efficiency of large and complex industrial facilities. In this paper an analysis of an integrated steel plant together with a new methodology to represent the resource efficiency is presented. The paper shows the importance of process integration as a methodology for the industry in their continued strive to strengthen its long-term sustainability.

An innovative and sustainable way for production of vanadium is to co-process vanadium titanomagnetite ores with vanadium-bearing slag from steel industry, via reduction, producing a hot metal containing about 2 mass% vanadium, 0.1 mass% phosphorus, and 0.4 mass% silicon. A vanadium-extraction method was developed for these hot metals using a semi-industrial-scale converter. Oxidation was carried out with an air jet enriched to 50 vol% oxygen and by top-charging up to 70 kg iron ore pellets per ton hot metal. The complete dissolution of pellets was achieved by deliberately creating good stirring conditions utilizing high momentary decarburization rates. The temperature could be controlled to around 1677 K at the blowing endpoint after the pellet coolant had been dissolved. Produced vanadium slags contained as high as 20 mass% V. The semifinished product contained about 3 mass% carbon and 0.1 mass% vanadium, corresponding to a vanadium yield of 94%. The phosphorus distribution to the slag was low when good stirring was maintained. The slag composition had a more significant impact than the temperature on the vanadium distribution. Laboratory-scale study also showed that the temperature impact on the composition of the liquid phase was minor. © 2017, The Author(s).

The iron and steel industry accounts for about 20% of the annual industrial energy utilization. The intensive fossil fuel consumption in steel industry is associated with CO2 emission. In the absence of economically feasible and efficient methods for capture and storage of enormous quantities of CO2 emissions from steel industry, the use of biomass products as a source of energy and reducing agents provides a promising alternative solution for green steel production. However, the biomass application in iron and steel industry is still limited and it suffers strong competition from fossil fuels. The challenges of biomass usage in steel industry are included technical and economic aspects which required synergy between steelmaking and bioenergy sectors. Although intensive work has been carried out separately, there is a lack of link between these two vital sectors. The present article provides a comprehensive review of recent research progresses which have been conducted on biomass upgrading and analysing the opportunities and obstacles for biomass implementation in iron and steel industry. In the first part, an overview on the energy consumption and CO2 emissions in different iron and steelmaking routes is clarified. Moreover, the potential approaches of biomass conversion processes and upgrading technologies are reviewed. In the second part, an attention has been paid to the utilization of torrefied/pyrolyzed biomass in the energy-intensive ironmaking processes. Biomass addition to coal blend during cokemaking and its influence on the product coke quality is discussed. The partial and complete substitution of coke breeze with biochar in sintering process and its influence on the product sinter quality is explained. The impact of charcoal top charging or injection into blast furnace has been elaborated. Benefits and limitations of biomass application in each process are thoroughly discussed. In the third part, an economic analysis of biomass implementation for low-carbon steel is addressed. 

The aim of this project was the development and implementation of the "Global Through-process Flatness Predictor and Coordinated Optimizer". This system should integrate all sub models including models of transfer conditions from process stage to process stage and perform a line-through process flatness prediction. However, analyses of the gained plate flatness in the various process routes showed that the reduction/evolution of flatness defects is nearly independent from the considered process route. Furthermore it has to be confirmed that flatness defects are not passed through the processing chain.

The use of zinc-coated steel (e.g. galvanized steel) in melting cycles based on Electric Arc Furnaces can increase the production of harmful dust and hazardous air emissions. A process to simultaneously preheat and remove the coating from the scrap surface is presented in this paper. The zinc in coating is removed in the gas phase by acid syngas combustion and collected in a dedicated recovery system. The article describes two possible process routes involving plastic waste pre-treatment, shredded plastic gasification/pyrolysis, scrap preheating and zinc recovery processes. The routes have been modelled in an integrated flowsheet, in order to allow a comprehensive simulation and optimization of the pre-treatment processes.. 

The use of Zinc-coated steel (e.g. galvanized steel) in melting cycles based on Electric Arc Furnaces can increase the production of harmful dust and hazardous air emissions. This article describes a novel process to simultaneously preheat and remove the coating from the scrap surface before the melting phase. The zinc in coating is removed in the gas phase by chloride containing syngas combustion and collected in a dedicated recovery system. Two possible innovative process routes are described, which involve plastic waste pre-treatment, shredded plastic gasification/pyrolysis, steel scrap preheating and zinc recovery processes. The routes have been modeled in an integrated flowsheet, in order to allow a comprehensive simulation and optimization of the pretreatment processes. The process optimization results in possible energy savings of over 300 MJ/t of preheated scrap charged in the Electric Arc Furnace for steel production. Moreover, a comparison among different scenarios according to economic and environmental criteria has been carried out. 

Recycling is of major interest in steel making for environmental reasons as well as economical. All process units produce secondary materials which are recycled, sold or put in landfill. This work evaluates simulated cases for recycling of materials at an integrated steel site. Case studies and industrial tests of different recycling options have been performed. The main focus has been on residues produced in significant quantities and materials put in landfill due to their physical or chemical nature. Chosen case studies have been tested in industrial scale and comprise of recycling of dust, sludge and ladle slag to the blast furnace. The results from test periods have been used to compare modelling with process parameters. Industrial tests show that it will be beneficial to recycle steel plant (BOF) sludge via briquettes to the blast furnace but the main issue is the drying of the sludge. Furthermore ladle slag can be used as slag former in the BF with no negative effect on the process or product. The main advantage is that the resource efficiency increases since less virgin material is used and the depositing of secondary materials is decreased. Major cost savings can be found if internal recirculation can replace raw material such as iron ore, coke and lime stone.

Recycling of materials is of major interest in steelmaking for environmental reasons as well as economical ones. This work evaluates new methods for recycling of waste materials in an integrated steel site. The study estimates how much material can be recycled and which order that would be the most beneficial with respect to costs, energy and deposits. The work shows conflicting results, where a decrease in deposits will increase the energy use in the system. However, according to the analysis, implementation of additional cases should improve the material efficiency, and cases are planned to be tested in the near future.

The use of available and cheap industrial producer gases as alternative fuels for the steel reheating furnaces is an attractive topic for steel industry. The application of producer gases for such furnaces introduces not only the complicated combustion system of Low Calorific Value (LCV) gases, but also several impurities that could be problematic for the quality of final steel products. The quality of steel can be highly affected by the interaction of impurities with iron-oxides at hot slab surfaces. In this research, the combustion of producer gases and the behavior of impurities at the steel slab surface are studied by aid of a novel coupled computational fluid dynamics (CFD) and thermodynamics approach. The impurities are introduced as mineral ash particles with the particle size distributions of 15-100 νm. The CFD predicted data regarding the accumulation of ash particles are extracted from an interface layer at the flaring gas media around the steel slab surface. Later on, these predicted data are used for the thermo-chemical calculations regarding the formation of sticky solutions and stable phases at the steel slab surface. The results show that the particles are more likely follow the flow due to the high injection velocity of fuel (70 m/s) and the dominant inertial forces. More than 90 percent of particles have been evacuated through the exhaust pipes. The only 10 percent of remaining particles due to the high recirculation zones at the middle of furnace and the impinging effect of front walls tend to stick to the side wall of slab in the heating zone more than the soaking zone. 

This study, in the area of non-destructive testing and measuring technology, shows that it is possible to inspect and determine the mechanical properties and micro structure of a material using electro-magnetic technique. The goal has been to on-line determine material properties like residual stress distributions, variations in tensile strength and fatigue strength in a material. In the project the latest in materials inspection using electro-magnetic methods combined with statistic modelling is used. The project has shown that these new methods can non-destructively determine the mechanical properties of a material or a machine detail. It is believed that this measuring technique has a clear place in industry.

The reducing of CO2 allowance promotes steel industry to mitigate CO2 emissions. Utilization of biomass e.g., as injectants in the blast furnace to replace pulverized coal (PC), has been proposed as one promising option to meet these requirements in the short- Term. The aim of this work is to integrate a biomass fast pyrolysis to the iron and steel industry and to investigate the potential effects on the energy consumption and CO2 emission. In this work, an iron and steel plant from Sweden was chosen as a case study. An optimization model was extended to cover the fast pyrolysis units in the system boundary. The fast pyrolysis plant produces different types of biomass products i.e., bio-char, bio-oil and bio-syngas. Different alternative to utilize biomass products within the system were included in the model. The investigation shows that the integration of a fast pyrolysis units has great potential on, not only reducing CO2 emission, the potential energy savings.

Significant quantities of waste materials or by-products are generated every day from the global steel industry. These materials contain substantial amounts of valuable compounds for example carbon or iron. Utilization of wet gas cleaning sludge from the blast furnace process is limited to as an additive in sinter production due to its fine particle size, high moisture and undesirable elements content. Test campaigns with a novel material handling process called Tornado have been carried out in order to enable utilization of recycled BF gas cleaning sludge in BF injection. Gas cleaning sludge containing over 40% of moisture was dried to less than 3% of residual moisture. The product from the Tornado-process: Powder with high Fe and C-contents was characterized for its physical injection and chemical properties. Injection trials were successfully carried out in the LKAB Experimental Blast Furnace to further validate material suitability to blast furnace injection as a reducing agent replacing PCI and coke as well as an iron bearing material replacing sinter and pellets. This paper describes the conducted work and analyzes the results.

A large amount of energy is required in the production of steel where the preheating of blast in the hot blast stoves for iron-making is one of the most energy-intensive processes. To improve the energy efficiency it is necessary to investigate how to improve the hot blast stove operation. In this work a mathematic model for evaluating the performance of the hot blast stove was developed using a finite difference approximation to represent the heat transfer inside the stove during operation. The developed model was calibrated by using the process data from the stove V26 at SSAB Oxelösund, Sweden. As a case study, the developed model was used to simulate the effect of a new concept of OxyFuel technique to hot blast stoves. The investigation shows that,by using the OxyFuel technique, it is possible to maintain the blast temperature while removing the usage of coke oven gas. Additionally, the hot blast temperature increases while the flue gas temperature decreases, which allows for an increase of the blast temperature, leading to improved energy efficiency for the hot stove system.

We demonstrate that muon tomography can be used to precisely measure the properties of various materials. The materials which have been considered have been extracted from an experimental blast furnace, including carbon (coke) and iron oxides, for which measurements of the linear scattering density relative to the mass density have been performed with an absolute precision of 10%. We report the procedures that are used in order to obtain such precision, and a discussion is presented to address the expected performance of the technique when applied to heavier materials. The results we obtain do not depend on the specific type of material considered and therefore they can be extended to any application.