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Highlights: [•] Process integration model of a joint recycling system between four steel plants. [•] Integrating a process to improve material efficiency and minimise the landfill. [•] System analysis to find a logistic solution needed to achieve the recycling system. [•] Results show a system in balance regarding generated and recycled materials. [ABSTRACT FROM AUTHOR]

At its integrated steel plant in Luleå, SSAB EMEA produces high strength steel via two basic oxygen furnaces (BOFs), type LD/LBE. The BOFs are charged with a mix of hot metal, scrap, and slag formers. The scrap has several functions, for example, as coolant to balance excess heat, and it contributes to high steel production rate and decreased CO2 emission. The optimal scrap to hot metal ratio is influenced by several factors, for example, the excess heat generated in the BOF versus target value of tapping temperature, content of contamination elements versus contents allowed in the steel, possible use of alloys in scrap to decrease the need of alloy addition and the scrap price versus the production cost of hot metal. The first two factors also affect the maximum amount of scrap to be charged. Furthermore, the available scrap exists as several types with different composition, properties, size, and price. For most scrap types there are also uncertainties in composition, which has to be considered. An optimization model has been further developed in combination with some statistic analysis techniques. The present work is focusing on the possibility to use the model as a tool to optimize and control raw material/scrap blending into the BOFs. On the basis of the statistical analysis technique, the scrap sorting in the model will be described, as well as development and introduction of an extended BOF sub-model. This model includes a scrap sorting function and a response on deviations in steel quality. Real production data is used to identify steel quality parameters with consideration of different combination of elements, for example, S, Cr, Ni, and Cu. The possible solutions with simultaneous consideration of steel quality, energy consumption and production cost are presented. [ABSTRACT FROM AUTHOR]

The implementation of the EU Emission Trading Scheme (ETS) started on January 1st 2005 according to national plans for allocating emissions rights. The steel industry is one of the industrial sectors included in this scheme. The objective of this paper is to investigate and evaluate the optimum solution(s) for European steel plants to meet their emission allowance with low reduction cost. An optimization model based on a Swedish steel plant is developed and used. Three scenarios were created in the model, i.e., internal changes within the steel plant, EU ETS, and the Kyoto Protocol's clean development mechanism (CDM). For the last scenario, China was selected as a country of the non-Annex I Party for the emission trading by CDM. The modeling results show that the studied plant will face an emission gap between allowed and calculated emissions in the near future. Compared to EU ETS, the implementation of CDM projects will make the plant reduce CO2 emissions at a lower cost. The internal changes within the plant will also play an important role for the solution of low abatement cost. The model developed could serve as a benchmark for the future emission trading simulation's purpose within the European steel industry. [ABSTRACT FROM AUTHOR]

Residue materials generated in the metallurgical industry have gained an increasing importance, both from the points of view of energy and material supply. A joint process integration model for the integrated steel plant system is developed and used in this paper. It takes into account both residue materials and energy recirculation for the system. The potential for increased recirculation and the effect on the system from an environmental point of view is presented, and implementations and practical experiences are discussed. The model developed can serve as a benchmark for different steelmaking operations and constitute a basis for the continuous work involved in material, energy, environment or economic analyses for the steel production system. [ABSTRACT FROM AUTHOR]

It is crucial for a steel making production system to operate at the lowest possible production cost, while satisfying stability and reliability conditions. To plan future production strategies, it is therefore important to be able to model the system behaviour when internal and external parameters are changed. In this study the sensitivity and stability of an optimised solution, of an integrated steel plant, have been investigated. The solution’s sensitivity has been analysed taking both internal process changes and external price variations into account, through applying both simulation and optimisation. The analysis also includes both costs and environmental issues such as carbon dioxide and sulphur emissions. Based on the methodology suggested, it is possible to determine the stability of the system solution, including both economic and environmental performance. [ABSTRACT FROM AUTHOR]

The coke oven plant has a central role in the iron and steel making process in an integrated steel plant. The subject of this research is to study how the production and energy system at the steel industry, with a connected combined heat and power plant, is affected by renovation of the coke oven. The aim is to investigate the interaction between the different processes and how the choice of system boundary affects the operation practice for the steel plant. MILP-based optimization models have been developed and used for the evaluation. The analysis shows that it is very important to take the interactions between the different production units in the system into consideration when making the analysis. A system optimization with a boundary including the whole system has a greater potential for minimizing the total system cost than one that only includes the processes where the actual changes are made. Conclusions are also drawn regarding the production practice for the specific system. [ABSTRACT FROM AUTHOR]

• Partial capture of steel-mill CO2 with excess heat is more low-cost than full capture • CO2 Capture from blast furnace gas outperforms end-of-pipe capture from flue gases • Available technology for excess heat recovery supplies steam at 2–7 €/t steam • Cost of capture (MEA) from blast furnace gas may be as low as 28 €/t CO2-captured • Partial capture is implementable if CO2 price is 40–60 €/t CO2 during plant lifetime Primary steelmaking in blast and basic oxygen furnaces is inherently carbon-intensive. Partial capture, i.e., capturing only a share of the CO 2 , is discussed as an option to reduce the cost of carbon capture and storage (CCS) and to realize a near-term reduction in emissions from the steel industry. This work presents a techno-economic assessment of partial capture based on amine absorption of CO 2. The cost of steam from excess heat is assessed in detail. Using this steam to drive the capture process yields costs of 28–50 €/t CO 2 -captured. Capture of CO 2 from the blast furnace gas outperforms end-of-pipe capture from the combined-heat-and-power plant or hot stove flue gases onsite by 3–5 €/t CO 2 -captured. The study shows that partial capture driven exclusively by excess heat represents a lower cost for a steel mill owner, estimated in the range of 15–30 €/t CO 2 -captured, as compared to full capture driven by the combustion of extra fuel. In addition, the full-chain CCS cost (capture, transport and storage) for partial capture is discussed in light of future carbon prices. We conclude that implementation of partial capture in the steel industry in the 2020s is possible and economically viable if policymakers ensure long-term regulation of carbon prices in line with agreed emission reduction targets beyond Year 2030. [ABSTRACT FROM AUTHOR]

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 CO 2 emission. In the absence of economically feasible and efficient methods for capture and storage of enormous quantities of CO 2 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 CO 2 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. [ABSTRACT FROM AUTHOR]

We have investigated and modeled the injection of biomass into blast furnaces (BF), in place of pulverized coal (PC) from fossil sources. This is the easiest way to reduce CO 2 emissions, beyond efficiency-improvements. The considered biomass is either pelletized, torrefied or pyrolyzed. It gives us three cases where we have calculated the maximum replacement ratio for each. It was found that charcoal from pyrolysis can fully replace PC, while torrefied material and pelletized wood can replace 22.8% and 20.0% respectively, by weight. Our energy and mass balance model (MASMOD), with metallurgical sub-models for each zone, further indicates that (1) more Blast Furnace Gas (BFG) will be generated resulting in reduced fuel consumption in an integrated plant, (2) lower need of limestone can be expected, (3) lower amount of generated slag as well, and (4) reduced fuel consumption for heating the hot blast is anticipated. Overall, substantial energy savings are possible, which is one of the main findings in this paper. Due to the high usage of PC in Sweden, large amounts of biomass is required if full substitution by charcoal is pursued (6.19 TWh/y). But according to our study, it is likely available in the long term for the blast furnace designated M3 (located in Luleå). Finally, over a year with almost fully used production capacity (2008 used as reference), a 28.1% reduction in on-site emissions is possible by using charcoal. Torrefied material and wood pellets can reduce the emissions by 6.4% and 5.7% respectively. The complete replacement of PC in BF M3 can reduce 17.3% of the total emissions from the Swedish steel industry. [ABSTRACT FROM AUTHOR]