Integrated Steel Mill Research Articles

Korean Integrated Steel Mill Project and Japan: The Economic Background of the Conversion of Korean Steel Industry in 1969

1969년은 일본의 기업과 정부에 의한 태도변화로 한국철강공업에서 결정적인 전환이 있었던 해이었다. 이러한 전환의 원인으로 기존에 크게 3가지 주장과 증언이 인용되고 있으나 본 고는 보다 객관적인 사회경제적 이유를 찾아보았다. 그 결과 일본이 한국의 종합제철공장 건설에 협조적 자세로 전환한 배경으로 3가지를 찾아내었다. 첫째는 미국이 주도권을 잡았던 KISA 협약이 붕괴됨으로써 종합제철 건설에서 일본이 주도권을 잡을 수 있었기 때문이었다. 둘째는 이 시기 철강공업 등 산업공해문제는 일본의 중요한 이슈의 하나로 되기 시작하였고 이에 일본은 향후 철강공업 재구성, 자본재생산설비 과잉문제 처리를 위해서는 철강공업설비를 판매할 크고 안정적이며 중장기적인 프로젝트가 필요하였기 때문이었다. 셋째는 장기간 준비하고 기술을 축적해 온 한국의 능력과 의지, 점점 표준화되고 있는 세계 철강공업의 노하우를 고려할 때 어차피 한국의 종합철강공장은 포기되는 것이 아니라 건설이 시작된다는 판단이 분명히 가능하게 되었기 때문이었다. 결국 한국의 대응이 중요하였다.

Evaluating product exchange options in integrated steel mills

There are two basic ways to produce steel on a large scale: using iron ore and coal in blast furnaces or employing ferrous scrap in electric arc furnaces. The first requires a larger initial investment but is more competitive in terms of scale gains. The disadvantage is the need for uninterrupted operation, reducing the flexibility to adjust production. To mitigate this problem, it is common to invest in steel rolling assets, generating the possibility of diversifying production and valuable product exchange options. In this work, employing Monte Carlo simulation, we calculate the value of a product exchange option in a steel mill composed of a blast furnace with a hot roller. The results show that this option can generate a significant increase on the NPV of blast furnace steel making projects, and also reveals the importance of choosing the type of stochastic process for the steel in determining the option’s value.

Costs and Potential of Carbon Capture and Storage at an Integrated Steel Mill

In this study different possibilities and the feasibility of applying carbon capture at an integrated steel mill based on blast furnace process, in order to reduce carbon dioxide emissions were studied. Technologies considered for capturing of CO2 are post-combustion carbon capture (PCC) and oxygen blast furnace route (OBF). Post-combustion capture for the integrated steel mill was evaluated in an earlier study by Arasto et Al. and Tsupari et Al. [1,2]. Implications of different capture amounts, different solvents for post-combustion capture and process integration levels to the greenhouse gas balance and operation economics are compared to the steel production base case with varying costs of CO2 emission allowances. Furthermore the effect of reducing the carbon intensity of steel production on the final steel production cost is evaluated.Iron and steel industry is responsible of around 5% of the overall global CO2 emissions [3]. Steel production based on the blast furnace and basic oxygen furnace-based route is the main technology corresponding to the growth in global steel production [4] and this technology route is also the main source of CO2 emissions in the iron and steel industry.The assessment of potential and cost for carbon capture and storage in the iron and steel industry is based on a case study on Ruukki Metals Oy's steel mill in Raahe. The mill is situated on the northeastern coast of the Gulf of Bothnia. It is the largest integrated steel mill in the Nordic countries producing hot rolled steel plates and coils. It is also the largest CO2 point source in Finland emitting approximately 4 Mton of CO2/year. Raahe steel mill produces district heat for use in the town nearby as well as for use onsite for heating of the premises. The power plant is connected to the national electricity grid, and thus it is possible to buy and sell electricity across system boundary.In contrast to power plant applications of CCS, CO2 emission sources at an integrated steel mill are scattered around the industrial site and the flue gases are led to several stacks. Due to this, the capture process evaluation is much more complex and requires system level optimization. Carbon capture processes and process integration options were modeled using Aspen Plus process modeling software and the results were used to estimate CO2 emission reduction possibilities and carbon abatement costs at the integrated steel mill from an investor's point of view. Different heat integration options and heat utilization scenarios were investigated and optimized with a custom-built CC-Skynet™ economics toolkit. Heat available for solvent regeneration varies between these heat utilization scenarios and thus different capture amount are investigated depending on the heat available for solvent regeneration in different case studies. Also different technologies related to oxygen blast furnace were considered, both for oxygen production and for top gas treatment. The application of oxygen blast furnace effects directly e.g. to the coke consumption of process and power production on site, and thus a new design considering new heat and process gas integration opportunities is essential.With a whole chain approach, including CO2 capture, processing, transport and storage, results show significant reduction potential at an integrated steel mill with carbon capture technologies. Ship transportation of CO2 is considered due to the location of the installation. Results show also the cost structure and feasibility of the studied technologies. Cost breakeven points for carbon capture at an integrated steel mill, for the plant owner and costs for globally avoided emissions are calculated. The study also reveals some major technical restrictions of the application. Finally the pros and cons of the technologies are compared and the role and potential of CCS as a carbon abatement tool in the European steel industry is considered.

Techno-economic Study of an Integrated Steelworks Equipped with Oxygen Blast Furnace and CO2 Capture

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.

CCS Feasibility Improvement in Industrial and Municipal Applications by Heat Utilisation

This paper describes implications of applying carbon capture and storage in combined heat and power (CHP) production and in steel industry through three case study approaches conducted in Finland. Utilisation of low temperature process heat from capture plant, air separation unit or CO2 compression in district heating system and/or industrial solutions offers significant potential to increase overall efficiency and feasibility of CCS processes. The effects of CCS on the local CHP systems were included within the studied system boundaries in order to evaluate the economics and emissions from investor's (local energy company) point of view. Effect of CCS on greenhouse gas (GHG) emissions and operation economics of the CCS cases are compared to the reference system with varying parameters of operation. Regarding the GHG emissions, besides the site emissions, the main effects on global GHG emissions are also taken into account by using system modeling and streamlined LCA.In the case studies the whole CCS chain, including CO2 capture, processing, transport and storage, was included. Carbon capture processes were modeled using Aspen Plus and Prosim process modeling software and the results were used in CCS plant economics toolkit (CC-Skynet™) to estimate CO2 emission reduction possibilities and carbon abatement costs. Studied case studies included three main applications which were studied in different operational situations. The properties of reference plants and CHP systems are based on the real operational CHP units and steel mill in Finland.The first presented application is retrofit of about 1000 MWfuel CHP plant with post combustion capture technology. Natural gas fired GTCC plant is part of relatively large district heating network including also other CHP units in the same network. The plant is situated on the coastal area of Southern Finland and it emits approximately 1.3 Mtn CO2/year.The second application is a greenfield about 500 MWfuel CHP plant situated on the coast of the Gulf of Bothnia and emitting approximately 1.5 Mtn CO2/year. The plant is based on a modern CFB-boiler which is equipped with oxy- fuel technology in the CCS case. The studied fuel-shares with and without CCS consisted of pure biomass, pure peat and biomass-peat co-firing. In the study it is assumed that the economic incentive for negative CO2 emission is included in EU ETS for Bio-CCS. The plant is connected to the existing district heating network where older CHP plant already exists. Another plant and limited district heat consumption in the area limits the benefits obtained from CCS heat recovery.The third application is an integrated steel mill situated on the coast of the Gulf of Bothnia and emitting approximately 4.0 Mtn CO2/year altogether. The mill is retrofitted for post combustion capture and implications of different capture amounts, different solvents and process integration levels are compared to the base case steel production with varying operational parameters. Process heat is utilized also as district heat but heat consumption in the district heat network is smaller than the amount of recoverable process heat in the mill.The results showed that significant improvements can be achieved by CHP in plants utilizing CCS, especially in the case of oxy-fuel. The feasibility of CCS is heavily dependent not only on the characteristics of the facility and the operational environment but also on the chosen system boundaries and assumptions. In combined heat and power plants, major improvements can be obtained with heat integration, especially, in the production of district heat. In the near future particularly large, new and flexible CHP plants, which can burn coal, biomass or peat, are seen as promising candidates for CCS in Finland.

Effect of Steel Making Slag on Castability of Medium Carbon Re-Sulfur Steel Grades

Abstract. One of the everlasting problems existing in alloy steel plant is clogging of Submerged Entry Nozzle(SEN) due to accumulation of De-oxidized/Re-oxidized products while casting Medium Carbon Re-Sulfur Steel grades(forging grades).After complete De-sulphurization and De-oxidation, liquid steel have been subjected to Ca-treatment which promote deep De-oxidation and deep De-sulphurization in addition to inclusion morphology control. Finally liquid steel have been injected with sulfur cored wire for chemistry requirement of 0.02-0.035%. All these conditions encourage thermodynamically favorable conditions for formation of various combination of oxide and sulphide inclusions which are highly detrimental to castability in continuous casting of integrated steel mill. This becomes one of the major process interruptions which directly terminate production capacity day by day and also affects the quality of cast product. As well said before “Best Slag Maker Is Best Steel Maker”, we mainly focused on secondary steel making slag at different stages, and found the relation of castability with respect to slag behavior. We arrived at optimal slag nature for better castability in continuous casting of steel.

Post-combustion capture of CO2 at an integrated steel mill – Part II: Economic feasibility

In this paper the economics of the technical possibilities presented in Part I (Arasto et al., 2013) for applying post-combustion CO2 capture at an integrated steel mill were studied. Implications of different CO2 amounts captured, solvents and process integration levels to the greenhouse gas balances and economics of operation are compared to the reference case without CCS trough several case studies using variable market prices of electricity and CO2 emission allowances.The break-even price (BEP) of CO2 emissions (e.g. CO2 emission allowances), where CCS becomes more profitable than the reference case, is about 72€/t CO2 with an electricity price of 100€/MWh in the most favourable studied case using a MEA solvent. For the more advanced solvents considered, the BEP level is about 64€/t CO2. With higher prices of electricity, the costs for CCS increase rapidly. The costs for globally avoided emissions, based on a streamlined life-cycle analysis, are generally higher than the BEP's, depending on the fuels that are assumed to eventually compensate the decreased electricity production in the energy system. The amounts of captured CO2 corresponding to the above presented prices in the most favourable cases are typically in the range of 2–3Mt CO2/a, which accounts for 50–75% of the site emissions.

Post-combustion capture of CO2 at an integrated steel mill – Part I: Technical concept analysis

In this study different possibilities for applying post-combustion capture at an integrated steel mill in order to reduce carbon dioxide emissions were studied. Implications of different amounts of CO2 captured, different solvents for post-combustion capture and different heat supply options for solvent regeneration to the energy balance and greenhouse gas emissions of the steel mill are compared to that of the base case for the steel mill.The case study is based on Ruukki Metals Ltd.’s Raahe steel mill that is situated on the coast of the Gulf of Bothnia. It is the largest integrated steel mill in the Nordic countries producing hot rolled steel plates and coils. It is also the largest CO2 point source in Finland emitting approximately 4Mt/year.Carbon capture processes were modelled using Aspen Plus process modelling software and results were used to estimate the potential for reducing CO2 emissions at an integrated steel mill from a plant operator's point of view. Different heat integration options and heat utilization scenarios were investigated. The heat available for solvent regeneration varied between these heat utilization scenarios and thus partial capture of CO2 was investigated with the CO2 amount captured depending on the heat available for solvent regeneration in the different case studies.The results of the study show a significant CO2 reduction potential using CCS. Approximately 50–75% of the emissions from the site could be captured using post-combustion capture. Capturing a larger amount of emissions would be technically less feasible due to the large number of small stacks around the large, integrated steel mill site.

Analysis on Environmental Management and Performance of POSCO

POSCO is the world's third-largest steelmaker which had an output of 35.4 million tones of crude steel in 2010. It currently operates two integrated steel mills in South Korea and operates a joint venture with U.S. Steel in California. As POSCO’s business expanded to overseas markets, the environmental management at the POSCO family level grows more important. Its current environmental management system incorporates environmental vision, policy, organizations and accounting system. In order to fulfill corporate responsibilities for the society and environment, POSCO establishes environmental objectives each year and put them into practice. In this paper, the POSCO environmental management methods and environment management performance were summarized. The treatment methods and recycling techniques of different metallurgical waste and resources (such as wastewater, dust, slag and sludge) were reviewed in details. At last, the author put forward some expectations for the environmental development and management of the Chinese iron and steel companies.

Some Benefits of Dynamic Simulation of Energy Systems in an Integrated Steel Mill

Some Benefits of Dynamic Simulation of Energy Systems in an Integrated Steel Mill

Radiative slab heating analysis for various fuel gas compositions in an axial-fired reheating furnace

A transient radiative slab heating analysis was performed to investigate the effect of various fuel mixtures on the performance of an axial-fired reheating furnace. The various fuel mixtures tested were assumed to be attained by mixing COG (coke oven gas) and BFG (blast furnace gas), which are the two main byproduct gases found in the integrated steel mill industry. The numerical prediction of radiative heat transfer was calculated using an FVM radiation solving method, which is a well-known and efficient method for curvilinear coordinates. The WSGGM (weighted sum of gray gas model) was also adopted to calculate the radiative heat transfer in composition dependent media. The entire furnace was divided into fourteen sub-zones to calculate the radiative thermal characteristics of the furnace without flow field calculations. Each sub-zone was assumed to have homogeneous media and wall temperatures. All of the medium and wall temperatures were computed by calculating the overall heat balance using some relevant assumptions. The overall heat balance was satisfied when the net heat input equaled the three sources of heat loss in each sub-zone, wall loss, skid loss, and slab heating loss.

Relationship between the Reduction Degree and Strength of DRI Pellets Produced from Iron and Carbon Bearing Wastes Using an RHF Simulator

Composite pellets utilizing iron and carbon bearing process waste materials obtained from the integrated steel mill was reduced in a simulated RHF (rotary hearth furnace) reactor at 1 523 K and 1 573 K to produce DRI (direct reduced iron) pellets with sufficient size, reduction degree, compression strength, and zinc removal as an iron and carbon substitute for the blast furnace. To obtain DRI sizes of more than 4.75 mm, bursting tests of composite green pellets with moisture were done and found to be dependent on the water content and initial charging temperature into the RHF. Bursting of composite green pellets with water content was dependent on the charging temperature. At a charging temperature of 1 273 K and 1 473 K, water content at 1 mass% and above resulted in pellet bursting, but at 1 073 K, water content only above 5 mass% resulted in appreciable pellet bursting. The compressive strength at various temperatures showed composite pellets containing carbon of 5.3 mass% can achieve blast furnace useable DRI at reduction temperatures of higher than 1 473 K, but composite pellets containing carbon of 8.3 mass% required reduction temperatures higher than 1 573 K. Optimum carbon of the composite seems to be at 9 mass% with a residual carbon content of less than 1 mass%, which results in a reduction of 80―90% with a compression strength of above 120 kg. This optimum condition has also shown Zn removal for the DRI to be above 85%. Higher (%C)/(%VM) showed lower reduction degrees indicating that increased volatile matter from the carbon source aided in higher reduction.

Investigation on Properties of Bentonite Type in Cold Bonded Pelletization of Flue Dust

In the integrated steel mills fabrication processes, the by-product of flue dust and electrostatic precipitator dust were found to be rich with large amounts of iron and carbon content and it could be recycled as a raw material for blast furnaces. In this study, we use the “Cold-bonded Pellet; CBP” technique to prepare the recycling samples for subsequent processing. Therefore, this study investigated under a fixed amount of bentonite added, the choice of different types of bentonite on the powder granulation performance and strength of particle duration effects, bentonite used as a basis for adjustment. The results showed that Bentonite samples of the granulation efficiency increase, relative to its yield and the rate of sticky increase. In general, CBP particle compressive strength increased, duration have increased, and found that curing condition B are large than the A method. In addition, by particle size analysis results show that, bentonite average particle size of 11-12μm have better compressive strength. Comprehensive assessment of granulation and mechanical properties, of which A label in four Bentonite can be preferred.

DEA 모형에 의한 제철용 석탄의 효율성 평가

This paper proposes a DEA model for the performance evaluation of each brand of coking coals in an integrated steel mill. The performance is defined as the efficiency which is the ratio of two linear combinations of the output factors to the input factors. There is only one input factor considered in the model : unit price of each brand based on CIF. Five output factors are chosen in consideration of their impact to the quality of cokes such as Ash, VM, LMF, TD, and Rm. Some of the output factors are treated as undesirable in DEA model because the quality criteria are given by the range. The CCR and BCC efficiencies are derived by the DEA model, and the scale efficiency is calculated, too. Each brand of coking coal is classified into four categories according to the CCR and BCC efficiencies, and the most inferior brands are identified as a result. The impact of the input and output factors to the efficiency is analyzed using a multiple regression, then the unit price is revealed as the most critical among them. Also, ANOVA results show that there exist efficiency differences among the coal types and the countries imported, respectively. Finally, the quantitative projection for the inefficient brands is performed if they are to be efficient. The result could be utilized in selecting the good or bad brands of coking coal based on the efficiency in an integrated steel mill. Also, this model will be used to assess the relative efficiency of a new brand of coking coal if it is a candidate to be imported.

Optimal and heuristic lead-time quotation for an integrated steel mill with a minimum batch size

This paper presents a model of lead-time policies for a production system, such as an integrated steel mill, in which the bottleneck process requires a minimum batch size. An accurate understanding of internal lead-time quotations is necessary for making good customer delivery-date promises, which must take into account processing time, queueing time and time for arrival of the requisite volume of orders to complete the minimum batch size requirement. The problem is modeled as a stochastic dynamic program with a large state space. A computational study demonstrates that lead time for an arriving order should generally be a decreasing function of the amount of that product already on order (and waiting for minimum batch size to accumulate), which leads to a very fast and accurate heuristic. The computational study also provides insights into the relationship between lead-time quotation, arrival rate, and the sensitivity of customers to the length of delivery promises.

Assessment of opportunities for CO2 capture at iron and steel mills: An Australian perspective

Abstract The iron and steel industry is one of the largest energy consuming manufacturing industries in the world, accounting for approximately 4.5% of the total world CO 2 emissions and over 2% of the total CO 2 emissions in Australia. Although significant work has been undertaken by the industry to reduce the levels of CO 2 emissions through initiatives such as increasing energy efficiency, recycling of by-product fuels, maximizing the recycling of scrap steel and increasing the use of renewable energy, for the industry to achieve further reductions in CO 2 emissions it will need to implement new or breakthrough technologies including carbon capture and storage (CCS). The objective of this study is to assess the cost and feasibility of implementing CO 2 capture at existing steel making facilities in Australia. The costs of capturing CO 2 from existing direct atmospheric emission points at an integrated steel mill and scrap mini mill are estimated. The results indicate that carbon capture might reduce the CO 2 emissions at a 5 million tonne plant by over 7.5 million tonnes annually at a cost of A$77 to A$100 per tonne CO 2 avoided. At a mini mill, CO 2 emissions could be reduced by 0.1 tonnes annually at a cost of over A$250 per tonne CO 2 avoided. Based on current technology, carbon capture would require a carbon price of at least A$65 per tonne emitted to be economically attractive.

A nested column generation algorithm to the meta slab allocation problem in the steel making industry

This paper addresses one of the key operational decision problems in the steel industry which is related to the allocation of orders to stock materials in the surplus inventory. The meta slab allocation problem can be stated as the ‘multi-stage multiple knapsack problem’ where the problem is to design slabs using orders with similar properties (the first stage) and allocating these designed slabs into the existing meta slabs in the inventory yard (the second stage). The objective of the problem is to maximise the allocated order weights in slabs and meta slabs. For the given problem, we propose a column generation algorithm, where a column in the master problem represents meta slabs and the sub problem is to design ‘bins’, here slabs with the given orders. The sub problem itself also becomes a multiple knapsack problem and we proposed a practical set-partitioning heuristic. The proposed algorithm was tested with daily operation data given from an integrated steel company in the Asia Pacific. The computational results showed that the proposed heuristic solved the real instances pretty well. The proposed algorithm was successfully deployed to the integrated steel mill.

Germ-line mutations, DNA damage, and global hypermethylation in mice exposed to particulate air pollution in an urban/industrial location.

Particulate air pollution is widespread, yet we have little understanding of the long-term health implications associated with exposure. We investigated DNA damage, mutation, and methylation in gametes of male mice exposed to particulate air pollution in an industrial/urban environment. C57BL/CBA mice were exposed in situ to ambient air near two integrated steel mills and a major highway, alongside control mice breathing high-efficiency air particulate (HEPA) filtered ambient air. PCR analysis of an expanded simple tandem repeat (ESTR) locus revealed a 1.6-fold increase in sperm mutation frequency in mice exposed to ambient air for 10 wks, followed by a 6-wk break, compared with HEPA-filtered air, indicating that mutations were induced in spermatogonial stem cells. DNA collected after 3 or 10 wks of exposure did not exhibit increased mutation frequency. Bulky DNA adducts were below the detection threshold in testes samples, suggesting that DNA reactive chemicals do not reach the germ line and cause ESTR mutation. In contrast, DNA strand breaks were elevated at 3 and 10 wks, possibly resulting from oxidative stress arising from exposure to particles and associated airborne pollutants. Sperm DNA was hypermethylated in mice breathing ambient relative to HEPA-filtered air and this change persisted following removal from the environmental exposure. Increased germ-line DNA mutation frequencies may cause population-level changes in genetic composition and disease. Changes in methylation can have widespread repercussions for chromatin structure, gene expression and genome stability. Potential health effects warrant extensive further investigation.

超臨界水、製鉄スラッジ、転炉スラグ間反応による水素系ガス製造と製鉄発生物の再資源化技術

超臨界水、製鉄スラッジ、転炉スラグ間反応による水素系ガス製造と製鉄発生物の再資源化技術

Analyzing the benefits of lean manufacturing and value stream mapping via simulation: A process sector case study

The “lean” approach has been applied more frequently in discrete manufacturing than in the continuous/process sector, mainly because of several perceived barriers in the latter environment that have caused managers to be reluctant to make the required commitment. We describe a case where lean principles were adapted for the process sector for application at a large integrated steel mill. Value stream mapping was the main tool used to identify the opportunities for various lean techniques. We also describe a simulation model that was developed to contrast the “before” and “after” scenarios in detail, in order to illustrate to managers potential benefits such as reduced production lead-time and lower work-in-process inventory.