[No abstract available]

Ore-based ironmaking generates a variety of residues, including slags and fines such as dust and sludges. Recycling of these residues within the integrated steel plant or in other applications is essential from a raw-material efficiency perspective. The main recycling route of off-gas dust is to the blast furnace (BF) via sinter, cold-bonded briquettes and tuyere injection. However, solely relying on the BF for recycling implicates that certain residues cannot be recycled in order to avoid build-up of unwanted elements, such as zinc. By introducing a holistic view on recycling where recycling via other process routes, such as the desulfurization (deS) station and the basic oxygen furnace (BOF), landfilling can be avoided. In the present study, process integration analyses were utilized to determine the most efficient recycling routes for off-gas dust that are currently not recycled within the integrated steel plants of Sweden. The feasibility of recycling was studied in experiments conducted in laboratory, pilot, and full-scale trials in the BF, deS station, and BOF. The process integration analyses suggested that recycling to the BF should be maximized before considering the deS station and BOF. The experiments indicated that the amount of residue that are not recycled could be minimized.

Depending on the operation of the blast furnace (BF), the main outlet of zinc from the furnace is more or less via the BF dust and sludge. As the dust is recycled to the BF, the sludge has to be de-zinced prior to recycling to prevent the accumulation of zinc in the BF. De-zincing and recycling of the low-zinc fraction via sinter have been reported. However, no research concerning recycling of upgraded BF sludge via cold-bonded briquettes has been performed. In the present study, a fine-grained BF sludge with low zinc content, generated by a BF operating on a ferrous burden of 100% pellets, was upgraded using the tornado process. The process simultaneously dried and separated the BF sludge into a high-zinc and a low-zinc fraction. The feasibility of recycling the low-zinc fraction to the BF using cold-bonded briquettes was studied on a laboratory-scale BF shaft simulator. On comparison with a reference briquette, the experiments indicated that 10 wt% of the upgraded BF sludge can be added to the briquette without negatively affecting the reducibility. Higher additions were found to render the briquette less reduced compared to the reference under test conditions corresponding to the central part of the BF. The strength of the briquettes was not compromised with the addition of the upgraded BF sludge, and a decision to study the briquettes in the LKAB experimental blast furnace was made in order to evaluate the behavior under actual BF conditions.

An experimental study was carried out to investigate the possibilities to use rolls made from Si3N4-TiN ceramic composite in hot rolling of steel. The results show that the wear of the ceramic material was lower than the wear of a reference cast iron. The results suggest that the Si3N4-TiN material is beneficial to use in a hot rolling process, on condition that the temperature of the work piece material is held sufficiently high. © 2008 Elsevier B.V. All rights reserved.

During melting of aluminum scrap a slag residue is formed. The slag residue, called black dross, has no industrial use and has to be landfilled. The work presented herein aims at developing a novel treatment process for the slag, converting it into a useful product for the steel industry and thereby replacing commercially available products made from virgin material. The concept consists of flash melting black dross and lime to form a synthetic slag former for treatment of high quality steel. Results from the modelling work indicate that the overall energy savings for an extended use of the developed product at the SSAB Europe Luleå site amounts to 31 GWh/y corresponding to 8 kt CO2/y, in addition to the process removing the need for landfill of around 20 kt of black dross per year with subsequent risk of leakage of toxic compounds.

The ULCORED coal based concept is simulated based on the production of syngas using existing coal gasification technology. The shifter gives the option to produce CO2-lean H2 from coal/biomass for in plant use. Large CO2 emissions arise on site from the use of natural gas in heating ovens and from the use of electricity in EAF melting. In the case of these coal based systems, production of "excess gas" to be used as fuel gas in various processes will reduce the CO2 emission for the total site.

In the BOS process liquid slag together with dispersed metal droplets, solid particles and process gases form an expanding foam. Certain process conditions may lead to excessive foam growth, forcing foam out through the vessel mouth, an event commonly known as 'slopping'. Slopping results in loss of valuable metal, equipment damage and lost production time. In the early 1980s a system for foam level and slopping control was installed at SSAB's steel plant in Luleå, a system based on the correlation between BOS vessel vibration in a narrow low frequency band and foam development. The technique, in this case with an accelerometer mounted on the trunnion bearing housing, soon showed its usefulness, for example when adapting existing lance patterns to a change in oxygen lance design from a 3-hole to a 4-hole nozzle. Estimating the actual foam height in the BOS vessel was of great importance in the recently completed RFCS funded research project "IMPHOS" (Improving Phosphorus Refining). Based on the earlier positive experiences, it was decided to further develop the vessel vibration measurement technique. Trials on an industrial size BOS vessel type LD/LBE have been carried out, this time with a tri-axial accelerometer mounted on the vessel trunnion. FFT spectrum analysis has been used in order to find the frequency band with best correlation to the foam level development. The results show that there is a correlation between vessel vibration and foam height that can be used for dynamic foam level and slopping control. © 2011 ISIJ.

Excess slag foam growth is a frequent problem in the BOS process. In the worst case, foam is forced out of the vessel and this phenomenon, commonly called slopping, not only results in loss of valuable metal yield but also in equipment damage and lost production time. In order to minimize slopping, accurate estimation of the foam level inside the vessel is an important part of BOS process control. In the top blown BOS vessel, slopping control is achieved using both static and dynamic measures. The most common implemented technique for dynamic foam height estimation and slopping control is the audiometer system. An alternative method, vessel vibration monitoring, has been investigated as part of the work in a RFCS funded research project called IMPHOS. In order to judge the usefulness of this method, parallel vibration and audio measurements have been carried out on 130 tonne as well as on 300 tonne BOS vessels. The results show that during stable process conditions there is good agreement between the two methods with regard to foam height estimation and, as vessel vibration and audiometry are largely independent of each other, a combination of the two is likely to increase significantly the accuracy of slopping prediction. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Injection technology has been an important subject from the early days of ladle metallurgy until the present. During the last decade, there have not been many publications in the area of injection technology. It is the author's opinion that with the challenge to find new solutions especially to environmental and energy related problems as well as better understanding of phenomenas from computer modelling, a new era of inventive injection technology developments is at hand. This is illustrated in the article with examples from six different areas where MEFOS is or have recently carried out R&D work related to issues from the injection technology field.

The usage of steelmaking process gases in thermoprocessing plants is the most efficient way to reduce the natural gas dependence and therefore both fuel costs and carbon footprint in steelworks. Furthermore NOx emissions can be cut by firing lean gases considering their low adiabatic flame temperatures. A European funded project aiming to enhance the usage of blast furnace gas (BFG) in steel reheating furnaces has been successfully accomplished by a multidisciplinary international consortium of research centers (ArcelorMittal Global R&D Asturias and Maizières, Centro Sviluppo Materiali, Swerea MEFOS, VDEh-Betriebsforschungsinstitut), burner suppliers (Tenova, AGA Linde) and end-users (ArcelorMittal). Three innovative preheated fuel gas burner technologies, namely double regenerative air-fuel, oxy-fuel and flat-flame burners, have been designed and manufactured for 100% BFG firing, so that the inherent constraints of burning very lean gases have been overcome. On the one hand, flameless oxy-fuel combustion with central preheated BFG, so that capital expenditures are limited, allowing easily furnaces retrofitting and potentially carbon capture. On the other hand, for air burners a dual honeycomb regenerator that preheats both air and BFG streams at the burner level, so that operating costs are reduced. Finally, an oxy-regenerative flat-flame burner that transfers homogeneously radiant heat to the load, combining the two beforehand mentioned technologies that are used mainly for high capacity burners (higher than 0.5-1 MW). These systems have been tested (long-term) at both pilot plant and industrial scale in order to define the guidelines for a safe application in the industrial environment, to address technical and economic issues and to put forward guidelines for retrofitting existing furnaces. Moreover, computational fluid dynamics (CFD) modelling has been carried out and validated with the pilot testing results, so that a numerical set-up has been defined for BFG firing. For this purpose a new radiation model for the radiative properties of the products of combustion of BFG has been developed, considering the low water vapor-carbon dioxide ratio. By means of preheating BFG with the waste heat content in flue gases stream, the typical operating temperatures of reheating furnaces (1350°C) have been achieved without natural gas enrichment, keeping the NOx emissions level below the European regulation threshold. © 2017 The Authors. Published by Elsevier Ltd.

plant trial has been performed, with recycling of ladle slag to the LD converter at SSAB EMEA, Luleå, Sweden. The effect of ladle slag addition on the slag and steel composition, together with the slag weight, was investigated with sampling both during the blow and at blow end. The addition of ladle slag resulted in an increase in slag weight between 1 and 2 t throughout the blow and an increase of 3 wt-% in the slag Al 2O 3 content. This indicated that the ladle slag melted during the initial stages of the blow and enhanced the early slag formation. Lime additions were reduced with 3·5 kg t -1 liquid steel without drawbacks on the phosphorus or sulphur refining. Heats with added ladle slag had an increase in blowing time with ~4% and an increased tendency for slopping. However, this can be handled by different lance and addition programmes. © 2012 Institute of Materials, Minerals and Mining.

The influence of recycled ladle slag on the basic oxygen furnace (BOF) process under production conditions was investigated in plant trials. More specifically, 25 heats with ladle slag additions and 23 heats without ladle slag additions were studied. Both steel and slag samples were collected, from which the chemical compositions were determined. In addition, several process parameters were monitored. Overall, it was found that recirculation of ladle slag during normal production conditions works fine. On the positive side, it was seen that the steel quality concerning the phosphorus and sulphur contents of liquid steel has, in accordance with previous studies, not been affected by the ladle slag additions. Furthermore, no major differences in the slag composition occur when the recycling of ladle slag to BOF is performed. Finally, in comparison to previous studies, the increased tendency for slopping when adding ladle slag could be eliminated with a change in the lance schedule. However, on the negative side, it was seen that the addition of ladle slag leads to an increased blowing time due to lower iron ore additions. Moreover, the slag weight at tapping increased due to an increased weight of added slag formers. © 2012 Institute of Materials, Minerals and Mining.

Blast furnaces that operate with pellets and sinter normally use high basicity sinter and acid pellets to balance the slag chemistry. When external additives are used, irregular slag formation occurs due to their uneven distribution in the burden. If basic sinter is used together with a large amount of acid pellets, all additives are incorporated in the iron bearing materials with an improved burden mixture as a consequence. During a campaign in the LKAB Experimental Blast Furnace, pellets and sinter were operated at an ultra low slag volume. A high amount of pellets was balanced with high basicity sinter. An improved blast furnace operation is shown when operating at ultra low slag volume and without external slag formers. During the test period, the blast furnace operation was smooth and stable, and the reductant rate was decreased.

The energy system of Luleå consists of the steel plant, a local CHP using process gases from the plant and the district heating system. Process integration work to improve the efficiency of the system is presently carried out by mathematical programming using a MILP tool (reMIND). Further improvements would need an improved possibility of the tool to consider the thermodynamic quality of the energy flows. This project aims to include exergy parameters in the node equations and object functions. This has been carried out for a test case, including a part of the system. Programming principles and some results are described. Copyright © 2010 AIDIC Servizi S.r.l.

Ferrous alloys using the TRIP and/or TWIP effect allow a combination of ultra-high strength and high ductility. The alloying concepts for theses steels are based on a manganese content between 12 and 25 % mass content. Other alloying components typically are aluminium and silicon. The presented research focusses on the assessment of economically viable process routes for the production of high manganese-content steel melts. Routes for mid- to long-term high production volume using iron-manganese-ores in a blast furnace or for direct reduction are presented. Being crucial for profitability different manganese sources and alloying concepts are discussed and evaluated under the aspect of tramp elements.

The energy network in Luleå consists of the steel plant, heat and power production and district heating. Global system studies are necessary to avoid sub-optimization and to deliver energy and/or material efficiency. SSAB began work with global simulation models in 1978. After that several more specialized process integration tools have been tested and used: Mathematical programming using an MILP method, exergy analysis and Pinch analysis. Experiences and examples of results with the different methods are given and discussed. Mathematical programming has been useful to study problems involving the total system with streams of different types of energy and material and reaction between them. Exergy is useful to describe energy problems involving different types of energy, e.g. systematic analysis of rest energies. Pinch analysis has been used especially on local systems with streams of heat energy and heat exchange between them.

A 3-dimensional CFD-model has been developed to simulate the natural convection flow in ladles. Qualified measurements of temperature and velocities in 107 and 7 tonne ladles have been made to verify the model. The downward convection flow at the ladle wall has been studied using radioactive isotopes and the thermal stratification has been studied by means of continuous temperature measurements. The experimental techniques are complex and additional numerical simulations have been carried out to study the effect of the measurement technique on the measurement error. The result indicates that the measurements are of sufficient accuracy for the validation. The measurements are compared to predictions from the numerical model. The main conclusion is that the theoretical CFD model gives a very accurate estimation of the temperature distribution during holding.

Rapid technical development together with developments in work organization makes it important to investigate possible ways to achieve a cost efficient process control of different metallurgical processes. This paper describes a research project, and proposes a human oriented Information Technology Strategy, ITS, for control of the Blast Furnace process. The method used is that of deductive reasoning from a description of the prevailing technological level and experiences from various development activities. The paper is based on experiences from the No. 2 Blast Furnace at Lulea Works but the conclusions do not at this stage necessarily reflect the opinion of the management and personnel or reflect their intentions for system development at SSAB.

Attempts to control the raceway depth have been made with many different technologies however none of them have had the capability to measure during operation. By using microwave technology the problem with interfering obstacles such as the coal injection can be avoided since the technology is not susceptible to this kind of interference. In this paper a novel approach using microwave technology to measure the raceway variations during operation will be described. MEFOS, The Metallurgical Research Institute AB, Lulea, Sweden, has tested an especially developed microwave unit to continuously measure the variations of the raceway during operation in the Blast Furnace. The trials were performed as a single tuyère trial on Blast Furnace 3 at SSAB Tunnplat AB, Lulea, Sweden with excellent results.

The steel industry involves energy-intensive processes such as combustion processes whose accurate modelling via first principles is both challenging and unlikely to lead to accurate models let alone cast time-varying dynamics and describe the inevitable wear and tear. In this paper we address the main objective which is the reduction of energy consumption and emissions along with the enhancement of the autonomy of the controlled process by online modelling and uncertainty-aware predictive control. We propose a risk-sensitive model selection procedure which makes use of the modern theory of risk measures and obtain dynamical models using process data from our experimental setting: a walking beam furnace at Swerea MEFOS. We use a scenario-based model predictive controller to track given temperature references at the three heating zones of the furnace and we train a classifier which predicts possible drops in the excess of Oxygen in each heating zone below acceptable levels. This information is then used to recalibrate the controller in order to maintain a high quality of combustion, therefore, higher thermal efficiency and lower emissions.

Large amounts of wood charcoal have been used in the past as feedstock for many industry sector, (energy, metallurgy, C extraction) but it has been replaced year by year by fossil coal, coke and synthetic materials. This trend characterised by coal consumption growth contributed rapidly to a wide range of damaging effects influencing European population and environment health (Global warming, ecosystem loss and degradation, loss of air, water pollution, respiratory admissions, etc..). All in the name of cost reduction. In fact, virgin forestry wood, usually consumed for charcoal production, is a high quality material with several valuable applications like construction, domestic heating, paper industry. For this reason, virgin wood is now traded at a cost of no less than 80 €/ton. Consequently, wood charcoal market price is not set below 250 €/t. This high market price avoids the use of wood charcoal in large market sectors where high amount of carbon, at low cost, are consumed, and where fossil coal has now fully replaced charcoal. One of these sectors is the Metallurgy and Steel industry. The development of new technologies recently brought to a big change in the renewable solid carbon sources. In particular, hydrothermal carbonisation technology, developed by INGELIA SL, demonstrated to be able to process wet low value biowaste streams, like municipal biowaste and food waste, producing a new biocoal, named hydrochar, which could represent an unlimited source of renewable carbon, at competitive price, for even large industry sectors. This study is focused on the characterisation, basic and process performances of three hydrochar samples obtained from INGELIA industrial Hydrothermal Carbonisation plant, from Green Waste (GW), Organic Fraction of Municipal Solid Waste (OF) and Orange Peel (OP). USTB executed performance tests on these three hydrochar samples, comparing them with two fossil coals: a typical bituminous coal, and anthracite, in order to evaluate the potential use of hydrochar as renewable fuel for the blast furnace injection.

Physical and chemical properties of coke samples excavated from LKAB's Experimental Blast Furnace (EBF) at MEFOS in Luleå, Sweden were characterized. A thermal annealing study the raw coke used in the EBF was also conducted in a horizontal furnace in a neutral environment at a range of temperatures up to 1650°C. Carbon crystallite height of the EBF coke and of the cokes treated in the laboratory furnace were measured by XRD while mineral phases were characterized by using SEM/EDS. The CO2 reactivity of the EBF cokes was measured by thermo-gravimetric analyser (TGA). The study demonstrated the strong effect of temperature on the modification of coke properties with special focus on carbon structure both under laboratory and experimental blast furnace conditions. The coke reactivity in the EBF was accelerated due to presence of recirculating alkalis in the coke, which increased as the coke descended in the EBF. The growth of carbon crystallite height of coke in the horizontal furnace was found to be of similar order as observed in the EBF under a similar range of temperatures. Comparison of carbon structure of laboratory treated cokes and the EBF excavated cokes indicated that carbon ordering of cokes is predominantly enhanced by the temperature rather than reacting gases or recirculating alkalis. The deterioration of coke quality such as coke strength (CSR) and abrasion propensity were related to coke graphitisation, alkalization and reactivity such that coke graphitisation was shown to have a strong impact on coke degradation behaviour. The study further implied that alkalis have a potential to influence the coke reactivity without affecting their graphitisation behaviour. The study also highlights the limitations of the CSR test for assessing the coke behaviour in an operating blast furnaces as it cannot simulate impact of graphitisation of cokes which is significant only at much higher temperatures.

The development and application of a 1-dimensional static blast furnace model, "Masmod", written in a common spreadsheet environment, is described. The model includes blast furnace, hot stove, and burden models with recent additions of other operations including CO2 stripping and top gas recycle. Although blast furnace modelling has become increasingly sophisticated, a relatively simple and flexible model is shown to be useful for evaluating burden options, equipment and operational strategies, and process development. Furthermore the Masmod model has been integrated with global steel plant optimization models and Process Integration models for more complex system analysis and optimization. © 2010 ISIJ.

The role of ferrous raw materials and iron ore agglomeration in energy consumption of integrated steelmaking has been evaluated using a system-wide model. Four steelplant cases were defined: typical European steelplant with sinterplant; Nordic steelplant with sinterplant; European steelplant with sinter:pellet ratio of 50%, and Nordic steelplant charging pellets and a small amount of briquettes. Energy consumption in the mining system were estimated from published statistics at 150 MJ/t for lump ore and sinter fines, 650 MJ/t for pellets made from magnetite and 1 050 MJ/t for pellets made from hematite. An integrated steelplant model including all major unit operations was used to calculate overall system energy consumption from iron ore mining to hot rolled coil. Adjustments were made accounting for energy benefit of ground granulated blast furnace slag in cement production, energy required for cement production required for briquetting, and excess BF and BOF gas producing electricity in a 32% efficient power plant. The system-wide net adjusted energy in the first three steeplant cases showed marginal improvement with use of high grade sinter fines and decrease of pellet/sinter ratio to 50% compared to typical European case. Nordic steelplant charging pellets and briquettes had a reduction in system-wide energy of 5% to 8% for charging pellets from hematite or magnetite respectively compared to the typical European steelplant charging sinter and pellets made from hematite ore. Replacement of sinter with pellets was mainly responsible for the improvement with smaller contributions from magnetite ore in pelletizing.

A techno-economic comparison of a reference integrated steelworks with a steelworks equipped with Oxygen Blast Furnace technology and CO2 capture is presented. Robust process and economic models were developed that could be customized to suit any integrated steel mill specific to their configuration. The whole operation of the steel mill including the OBF-system was modeled for a European Atlantic coastal scenario using a spreadsheet-based model. An amine-type solvent system MDEA/Pz was chosen as solvent to capture CO2 from the raw BF topgas. A discounted cash flow through-cost model was used for economic analyses. Results show that the OBF with CO2 capture offers a significant potential to reduce the overall CO2 emissions from an integrated steel mill achieving 47% CO2 avoidance at a cost of ∼$56/t CO2 for the given assumptions. The avoidance cost is particularly sensitive to the cost of energy, capital expenditure and discount rate. Further improvements in oxygen production, CO2 capture system, and optimization of power/heat integration between steel mill, CO2 capture plant and power generation could lead to lower CO2 avoidance costs.

Swedish steel producers are particularly interested in the recovery of vanadium oxide from the steelmaking slag because of its high content in the LD-converter slag. Hence, optimization of the vanadium recovery has strong economic and environmental impact. Solving the problem with vanadium recovery from the slag requires development of reliable technique for assessing the oxidation state of vanadium. This paper summarizes methodology for the robust analysis of the Ca-Si-based slag materials containing vanadium oxide in different oxidation states utilizing XPS. The measurements show that because of high oxygen affinity of vanadium oxides and number of oxidation states, only fracturing of machined specimens in an ultra-high vacuum chamber, connected to XPS, allows accurate evaluation of oxidation state of vanadium in slag. Proper charge compensation, required due to non-conductive nature of the slag specimens, is considered to be the main problem faced during analysis. As neither carbon nor oxygen signals were proven to be appropriate reference point for charge referencing in this material, the calcium 2p peak position at 347.0 eV, characteristic for CaSiO3, shown to be the most stable and reliable binding energy calibration reference and was used during the charge compensation. Results indicated that in the case of the studied slags, vanadium oxides present are formed preferably by mixture of V2O3 and VO2, depending on the reducing potential of the controlled atmosphere applied during the slag synthesis. Copyright © 2014 John Wiley & Sons, Ltd.

Knowing the distribution of the materials in the blast furnace (BF) is believed to be of great interest for BF operation and process optimization. In this paper calibration samples (ferrous pellets and coke) and samples from LKAB’s experimental blast furnace (probe samples, excavation samples and core-drilling samples) were measured by the muon scattering tomography detector to explore the capability of using the muon scattering tomography to image the components in the blast furnace. The experimental results show that it is possible to use this technique to discriminate the ferrous pellets from the coke and it is also shown that the measured linear scattering densities (LSD) linearly correlate with the bulk densities of the measured materials. By applying the Stovall’s model a correlation among the LSD values, the bulk densities and the components of the materials in the probe samples and excavation samples was established. The theoretical analysis indicates that it is potential to use the present muon scattering tomography technique to image the components in various zones of the blast furnace.

In this work, the effectiveness of using briquettes made from chromite ore, mill scale, and petroleum coke for direct chromium alloying is tested by induction furnace trials carried out in three different scales. The experimental results show that steel scrap can be alloyed with chromium by the chromite ore in the briquettes and the Cr yield from the chromite ore increases with the increase in mill scale addition to the briquettes: the more mill scale is added to the briquettes, the lower the mass ratio of Cr to (Cr + Fe) would be, leading to a higher Cr yield from the chromite ore. Specifically, the maximum Cr yield from the chromite ore is 99.9% when the mass ratio of Cr to (Cr + Fe) in the briquettes is 0.05, and being 93.0% when the ratio is 0.10. However, when the ratio of Cr to (Cr + Fe) in the briquettes reaches 0.20, the maximum Cr yield is only 67.1%. The reduction of chromite ore under the present experimental conditions is promoted by a solid-state reduction mechanism.

In this paper, the reduction of chromite ore by coke was investigated by means of thermogravimetric analysis under non-isothermal conditions (from room temperature to 1823 K). The fractional reduced samples were examined by SEM/EDS and X-ray diffraction analyses. The experimental results showed that the reduction of iron in the chromite ore started before that of chromium in the ore, and the reduction of chromium and iron in the ore overlapped to some degree. Chromium iron carbide (Cr,Fe)7C3, was found to be the intermediate phase during the reduction, and a chromium gradient was found in the spinel phase of the fractional reduced sample at 1673 K. A four-stage reduction process was proposed: one stage involving the reduction of iron in the chromite ore and three stages involving the reduction of chromium in the ore. The activity aspects of component FeCr2O4 and component MgCr2O4 in the chromite ore were considered. The difficulty in the reduction of the chromite ore is attributed to the fact that, as the reduction proceeds, the activity of the component MgCr2O4 in the fractional reduced ore will decrease to a very low level, which makes further reduction very difficult.

Relatively robust predictive models for the steel reheating processes are crucial for efficient control and optimisation of reheat furnace operation while ensuring good quality of the heated products. This paper describes the development of a two-dimensional (2D) mathematical model, based on the zone method of radiation analysis, which is capable of simulating the thermal performance of a walking-beam reheating furnace, such as the temperature distribution inside the furnace and the heated stock. The models were initially validated using experimental data supplied by Swerea MEFOS, Sweden. The validated models were further used to investigate changes in the furnace operating conditions, such as production rates and production delay. The results show that the model predictions are in agreement with the measured data and that the model can reasonably respond to the changes in different operating conditions. The developed model has the potential to predict durations of furnace operation of a thousand times faster than the actual run time, and it also demonstrates the feasibility and practicality for incorporation into a model based furnace control system.

When raceway conditions are changed, e.g blast parameters or selection of injection material, additional measurements and monitoring of raceway can support evaluation of the effects on raceway conditions. Two types of measurement methods have been tested during injection trials with BF flue dust at the SSAB EMEA BF in Oxelösund and the LKAB Experimental Blast Furnace (EBF®). The raceway depth was measured using microwave technique and a camera was installed for viewing the raceway when the peep hole was occupied by the depth measurements equipment. Temperature estimation was made on thermal radiation guided via an optical fibre from the raceway to a spectrometer. Evaluation methods were developed based on Planck radiation law. The measurement techniques and their use for monitoring of raceway conditions are discussed.

Strip cleanliness in the industrial cold rolling mill must be controlled by optimizing the roll, strip, lubricant and process parameters. Obtained experimental evidence in this work shows which of these parameters have a significant influence on strip cleanliness. The experiments were carried out on a plate-out tester and on cold rolling pilot mills. New findings were the influence of thickness reduction on strip cleanliness: a high reduction in the first stands of a tandem mill results in poor strip cleanliness, but in the latter stands a high reduction results in a better strip cleanliness than a low reduction. Furthermore the beneficial influence of a chrome coating on the work roll was shown to be related to the better adherence of oil to this type of work roll. This article provides a concise overview of the experimental results achieved and their interpretation. © Tata Steel Nederland Technology B.V., 2011.

Temperature control is very important in wire rod production. A short rapid water cooling equipment for wire rod has been studied in pilot-plant trials at MEFOS. The equipment is mainly a water filled tube, fed by a housing with a circumferential nozzle. Cooling experiments were done with 25 mm C-Mn steel bars rolled to 19 mm bars. The cooling equipment diameters were 25 mm and 30 mm. The decrease in temperature was measured as well as feeding water pressure in the housing and water pressure in the cooling tube. The heating temperature, rolling speed, cooling tube length and water pressure were changed for the 25 mm equipment. Temperature difference between head and tail ends of the bar was also studied for the 25 mm equipment. Nozzle gap, tube length and water pressure were changed for the 30 mm equipment. A statistical analysis of the cooling results for the 25 mm equipment showed that the cooling was dependent on the water pressure, rolling speed and the furnace temperature. A change in water pressure from 1.4 to 22.8 bar increased the cooling 90 °C. The temperature difference between the ends of the bar was only influenced by the initial temperature difference and the bar temperature. The results from experiments with 30 mm equipment showed no effect on nozzle gap and tube length. The cooling effect of 30 mm equipment at pressures from 2.5 to 5 bar is similar to 25 mm equipment. The variation of cooling with pressure is higher compared with 25 mm equipment. The water consumption in a 30 mm equipment is twice the consumption in a 25 mm equipment at the same pressure.

A process integration model is developed based on mixed integer linear programming. The analysis is carried out using the reMIND software in combination with the commercial optimization software CPLEX. The steam production (heat recovery boiler, bark boiler and steam turbines) and the process steam consumers (digester, evaporation plant, bleaching plant as well as pulp dry machine and paper making machine) are modeled as separate modules and thereafter linked and are validated using the operation data from a pulp and paper mill in the Northern Sweden. The whole plant is simulated and initial optimization runs are performed in which the cost is to be minimized. Copyright © 2010 AIDIC Servizi S.r.l.

A detailed mathematical process integration model of a pulp and paper mill in the Northern Sweden has been developed. The main objective of this work has been set to describe the practical development of the model with particular emphasis on the development of the digester and evaporation plant sub-models. Actual plant measurements have been used to validate the model. By implementing the sub-models into the complete plant model, the influence of different operation parameters on the overall plant performance has been investigated. Furthermore, introductory studies with the main objective to minimize the plant energy cost have been carried out. © 2012 Elsevier Ltd.

Basic oxygen furnace (BOF) slag contains a significant amount of iron-containing species, which is considered to be iron resources and therefore need to be recovered. In this work, the oxidation behaviour of BOF slag under air (at selected oxidation temperatures and holding time) was investigated to explore the potential of transforming non-magnetic wustite in the BOF slag into magnetic spinel, which may subsequently be recovered by magnetic separation. The experimental results show that the iron-containing spices in the BOF slag can be oxidised into magnetic spinel phases in the investigated temperature range of 1000–1150°C and thereafter be recovered by magnetic separation. The formation of these phases is closely related to the oxidation temperatures and holding time: a higher oxidation temperature and longer holding time lead to a larger amount of formed magnetic species; however, the amount of formed magnetic species decreases at elevated temperature (>1050°C) and with extended holding time (>40 min). 

As increase of productivity and good product quality are constant goals within the rolling industry, the lubrication formulation is constantly modified or changed to meet these goals. However, it is a costly and not always problem free process to make industrial on-site tests of new lubricants. A more cost efficient way is to test the lubricants on a pilot scale first. The advantage is that there are good probabilities to isolate the lubricant performance and compare the outcome with the performance of other lubricants under controlled conditions. The pilot mill tests in this investigation were performed on 90 mm wide and 3 mm thick hot rolled aluminum strips. During the pilot rolling mill trials several products were tested. The tests were aimed at optimizing the performance of a traditional emulsion as well as a new lubricant, in this case a conditional emulsion. Different formulations were tested where additive levels, HLB values and viscosity were varied to test the performance of the traditional lubricant. The active components and the cloud point of the conditional emulsion were also varied and evaluated. Different lubricants were applied sequentially by a direct change of lubricant source during the rolling of one strip and under constant rolling conditions such as strip speed, strip tension and reduction. Parameters computer logged are strip back and forward tension, strip entry and exit speed, motor current, reduction, roll and strip exit temperature, upper and lower roll torque and roll force. The project target is to: • Improve the lubricant selection process • Allow an accurate application procedure testing facility • Increase the knowledge of novel products • Introduce the pilot mill as a testing facility one step before industrial on-line tests The test results show that changes of lubricant give an immediate response in rolling forces and rolling torques, which makes a direct comparison between different lubricant performances under identical mill conditions possible. Results from similar tests for the steel industry indicated a direct transferability to the industrial case. The strips surfaces will also be thoroughly analyzed but these analyses are not complete and will not be further discussed within this paper.

Swerea MEFOS pilot mill has been used as a rolling lubricant development tool. The objectives were to improve the lubrication during rolling and thereby improve the operation of the rolling mills. This was done taking into account both the technological aspect, rolling mill output, and the ecological aspect, investigating ways to use rolling lubricants that are more ecologic sustainable, i.e. alternatives to oil-based lubricants as well as the recycling/recovering of oilbased lubricants. Oil-in-water emulsions and an aqueous solution, by the producer termed a conditional emulsion, were tested where the lubricant formulation was altered to optimize the performance for hot rolling of aluminium. Cold-rolling tests were also run on steel coils, where the presence of rust protective oil was studied as well as the influence of aged emulsion behaviour compared with fresh emulsion. Finally, Sapa developed a vacuum evaporator system for recovering oil from dumped emulsion generated during aluminium hot rolling, followed by separation, centrifugation, and flocculation. The cleaned concentrates were reconditioned for reuse. The recycled and recovered emulsion was tested and compared with the original fresh emulsion in Swerea MEFOS pilot mill with results as good as the fresh emulsion. © Swerea MEFOS AB, Luleå, Sweden, 2011.

During the annealing heat treatment following cold rolling of a 304L austenitic stainless steel sheet material, the material goes through changes in microstructure and mechanical properties. The cold rolling history together with the time/temperature trajectory in the annealing furnace can be used to model the final microstructure. In this work, physically based models for recrystallization and the following grain growth was created for the prediction of the microstructure evolution- both grain size and grain size distribution-, and an artificial neural network, ANN, was added for secondary effects. This is more commonly referred to as a hybrid model. The microstructure hybrid model was tested and validated against cold rolled and annealed production sheet material of various thicknesses and reductions, where the grain size and grain size distribution was measured by Electron Back Scatter Diffraction, EBSD. The recrystallization and grain growth parameters and functionality were fitted for non-isothermal conditions, against experimental tests of cold rolled material. Given process history and time/temperature data from the annealing heat treatment, the model can predict the microstructure, average grain size and grain size distribution with high accuracy and the executing time is short which makes it suitable for in-line use. © (2014) Trans Tech Publications, Switzerland.

Some highlights from the Jernkontoret Research with focus on the modeling work of the last decade are presented. First the concept of a fundamental mathematical model is discussed. Thereafter, a short review of growth and separation models based on fundamental modeling of ladles is presented. Then, recent modeling efforts within Jernkontoret's Research are highlighted.

In hot forming processes at elevated temperatures like wire rolling, microstructural changes such as repeated dynamic recrystallisation and grain growth occur. An experimental method to obtain the flow stress behaviour and to capture the recrystallised microstructure for materials subjected to large deformations, high temperatures between 900 and 1200°C and high strain rates around 5000s-1 is presented. The method is based on the split-Hopkinson pressure bar arrangement complemented with an inductive heat source. Furthermore, a momentum trap is added to ensure that the specimen is loaded only once. By quenching the specimen directly after the single loading, the dynamically recrystallised microstructure is preserved. The quenching is performed within 0.1s of loading by dropping the specimen into a water bath. By applying the momentum trap technique, the compressive loading of the specimen could be interrupted at a strain level slightly above the strain level corresponding to the peak stress, which is a good estimation for the onset of dynamic recrystallisation. © 2014 Wiley Publishing Ltd.

In order to characterise the mechanical response of materials in manufacturing processes, such as wire and bar rolling involving very high strain rates, temperatures and level of straining, an experimental device is presented. The device is suitable for testing at strain rates up to approximately 4000 s-1, temperatures up to 1200 °C (≈1500 K) and strains around 0.5. It is based on the classical Split Hopkinson pressure bar and is complemented with an inductive heating source for achieving requested temperatures. By keeping the specimen separated from the Hopkinson bars just until an instant before impact (50 ms) considerable cooling and temperature gradients in the specimen are avoided. Three steel grades, two stainless steels and a high-speed steel, were tested. Four different material models whose parameters were fitted to the obtained experimental data were used for mechanical characterisation: two empirically based and two physically based. Overall, one of the physically based models showed the best agreement between experimental results and the predicted flow stresses.

This deliverable reports the survey done in SCRREEN project in Task 4.3 relating to environmental trends and CircularEconomy (CE) aspects of CRM production. For each CRM, the Circular Economy aspects were addressed in order to identifythe gaps that limit performance of the processing chains, hinder closing the loop and hinder a zero-waste CRM production.Information on processes, production, solutions and eco-design principles for closing the loop of raw materials in order tosupport the zero-waste point-of-view, resource efficiency and energy efficiency simultaneously were gathered. In addition, theaspects supporting Circular Economy were evaluated trying to resolve the identified challenges. Lastly, the environmentalissues e.g. toxicity related to CRMs production were reviewed.

It has always been of greatest importance to control the temperature distribution in the products throughout the hot strip rolling process including the final coiling operation. A computational model of the latter has been developed and validated, which is presented in this paper. Furthermore, the influences of the different parameters on the transient thermal distribution are evaluated. The formulated model as accounts for twodimensional heat conduction is assuming axi-symmetric conditions. Temperature dependent properties are accounted for results in a nonlinear heat conduction problem that is solved by use of the Finite Element Method (FEM). The calculations have been validated by two full scale measurement campaigns and show a good agreement with measurements. © 2011 ISIJ.

When producing hot strip, HSLA(High Strength Low Alloyed) products the coiling temperature and the subsequent coil cooling is of great importance for the final mechanical properties. A thermo-mechanically coupled model has been developed where the anisotropic stress dependent thermal properties caused by the layered structure and the asymmetric cooling are included. Additionally the precipitation hardening effect on the yield strength, influenced by the thermal history during cooling was compared with mechanical tensile testing along the strip length at SSAB EMEA works in Borlänge, Sweden. Good agreement between measured and predicted yield stress variations in head and tail was obtained. © (2014) Trans Tech Publications, Switzerland.

When producing hot strip, HSLA(High Strength Low Alloyed) products the coiling temperature and the subsequent coil cooling is of great importance for the final mechanical properties. A thermo-mechanically coupled model has been developed where the anisotropic stress dependent thermal properties caused by the layered structure and the asymmetric cooling are included. Additionally the precipitation hardening effect on the yield strength, influenced by the thermal history during cooling was compared with mechanical tensile testing along the strip length at SSAB EMEA works in Borlänge, Sweden. Good agreement between measured and predicted yield stress variations in head and tail was obtained. © (2014) Trans Tech Publications, Switzerland.

ULCORED is the concept suggested by SP 12 to meet the demand of reduced CO 2 emission using iron ore and gas based direct reduction for steelmaking. The concept includes the use of 100 % oxygen, POX (partial oxidation) instead of reformers, shifter for production of CO 2 free reduction/excess gas and the reducing agent being either natural gas or syngas from coal/biomass.

Process Integration is a common name for system oriented methods and integrated approaches to complex industrial process plant design. It is a multi disciplinary approach which consists of mathematical, thermodynamic and economic models and methods. Process Integration is a product of the increasing awareness of energy conservation needs in the industry. Some of the methods are therefore essentially related to examination of energy systems. Research in Process Integration has also been broadened to include raw material efficiency, emissions reduction and process operations. In the steel industry Process Integration projects can be further developed to powerful instruments for strategic management which includes decision making in connection with design of new plants, reshape of existing plants, or process development projects. Process constraints and alternative design options can be evaluated on equal terms. The implementation of recommended measures in this type of studies is often closely linked to other strategic decisions. This presentation gives an overview of past projects in Sweden where Process Integration has been applied in steel industry to minimise energy consumption, emissions and residue material flows. Some thoughts about the future use of Process Integration methods in the steel industry are also included.

Increased use of scrap in steelmaking including scrap use in BOF has a high economic and environmental potential in terms of increased productivity, energy saving and reduced emission of CO2. Preheating and surface cleaning of steel scrap is a concept developed by MEFOS in a four year research program funded by MISTRA, Swedish Foundation of Strategic Environmental Research. The process concept consists of four major steps: 1) Combustion of ASR or other waste fuel and composing of the gas composition. 2) Scrap heating and cleaning in a shaft where the coated zinc is removed as ZnCl2 and scrap is heated to about 600°C. 3) Dust separation for recovery of metal zinc. 4) Gas cleaning. This paper will describe the process concept and highlight the major results from preliminary trials around the scrap heating and cleaning shaft.