Slag, steel and greenhouse gases (original) (raw)
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The Carbon Cost of Slag Production in the Blast Furnace: A Scientific Approach
Journal of Sustainable Metallurgy, 2016
The quality of raw materials (iron ore, coal, and coke) has a clear impact on the carbon emissions of the hot metal production in steel making. So far, very little work has been done to measure and quantify this impact. Yet for benchmarking, technology choice and general carbon optimization are important elements. The total slag production of a blast furnace gives an accurate and relevant measure of the raw materials quality and is the main variable on which plant operators have no control. To quantify the impact of a varying amount of slag produced together with hot metal, a method is developed based on a differential approach. For a number of different blast furnaces with different operating points and burden compositions, the carbon footprint or carbon cost of slag production is determined using this method and a robust value for the carbon cost of the slag is derived. This value can also be used in the comparison of the carbon cost of different steel making routes or in life cycle assessments for steel and slag applications. Keywords Blast Furnace Á Hot Metal Á Benchmarking Á Slag allocation Á Carbon efficiency Á CO 2 emissions Á Granulated blast furnace slag Á Life cycle analysis The contributing editor for this article was Bart Blanpain. Jean-Sébastien Thomas-Deceased Dec 2014.
Steel Slag and Waste Management
Key Engineering Materials, 2004
Steel slag is a waste material produced during the process of steel making. For many years, a large amount of steel slag was deposited in slag storing yards, occupied farmland, silted rivers and polluted the environment. Many steel plants in the world have already taken up innovative waste recycling technologies with the ultimate objective of 100% recycling. There is much to be improved in using steel slags in Turkey. The comprehensive utilization of steel slag is important for environmental protection and resource reuse in Turkey and abroad. It is clear that steel slag must meet appropriate performance specifications before being adopted for a particular application. The aim of the present research was to characterize steel slag from a Turkish company and compare to the steel slags from various countries. Application possibilities have been sought by comparing properties to the other steel slags.
Journal of Industrial Ecology, 2015
State-of-the-art technologies that implement the 'Industrial Ecology' concept only make it to the market if environmental gains and economic benefits are significant. Therefore, the paper investigates, in an interdisciplinary way, two innovative technologies that valorize Stainless Steel (SS) slags as block masonry (bricks): carbonation and thermo-alkali-activation. The technical, environmental and economic features of three SS bricks-solid bricks, perforated bricks and lightweight aerated blocksare compared to commercially available construction materials. Although the produced bricks meet industrial standards, technical challenges such as optimization of alkali addition and use of metal molds should be dealt with before upscaling to industrial production. A cradle-to-gate Life Cycle Analysis (LCA) that aggregates the results of the various impact categories shows that the environmental impact of solid and perforated SS bricks is lower than the impact of conventional clay-baked bricks thanks to the avoidance of additives for slag stabilization and energy consumption for sintering clay. The impact of aerated SS bricks was found to be similar to the commercially available aerated blocks. More specifically, the CO2 uptake from carbonation reduces the overall environmental impact whereas use of alkalis increases the impact. A SWOT analysis highlights the economic advantages of SS bricks originating from lower energy requirements, reduced dependence on primary resources and improved metal recovery from slag. However, in order to apply the innovative technologies at industrial scale, challenges related to processing conditions, feedstock variability and potential competition from existing brick suppliers have to be overcome. used as aggregates, mostly in road construction, kept in temporary storage or landfilled (Nielsen 2008). However, use as road aggregate is a low-value application for the slag. Moreover, borate additions increase the risk of leaching (Shen and Forssberg 2003), posing a further environmental and legal challenge for the use of this slag (JRC 2010). Use of SS slag as construction material not only avoids slag disposal, but also, to some extent, limits the utilization of virgin resources for the production of construction materials. Construction materials from the current raw material sources and processes account for a large portion of the global anthropogenic carbon dioxide (CO2) generation. For example, the production of ordinary Portland cement (OPC) contributes to about 5-8% of the total global CO2 emissions (van Deventer et al. 2010; The World Business Council for Sustainable Development,www.wbcsd.org.). As a result, the "Cement and Technology Roadmap 2009" has laid a task for a 50% reduction by 2050 of global CO2 emissions from cement production (WBCSD 2009). Also, yearly emissions of the ceramic industry are estimated at 400 Mtons of CO2 (IEA 2013). Considering this, the production of construction materials from alternative sources like SS slag is an ambitious and promising option. Recent technical research has developed construction materials in the form of masonry bricks from fine AOD and CtCs SS slag by applying two innovative processes (Salman et al 2014): 1) thermo-alkali-activationa process where the latent hydraulic (binding) property of the slag is activated by use of alkalis and high temperature and 2) carbonationa process where CO2 is used to bind the slag particles together by the formation of stable carbonates. Fig. 1 illustrates that, in line with the 'Industrial Ecology' paradigm, both technologies unlock slag properties in order to substitute energy and primary material consuming production processes (Graedel and Allenby 1995; Lifset and Graedel 2002).
Utilization of iron and steel slag in building construction
PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON SUSTAINABLE MATERIALS AND STRUCTURES FOR CIVIL INFRASTRUCTURES (SMSCI2019), 2019
The production of cement results in emission of greenhouse gases in atmosphere. The concrete industry is constantly looking for supplementary cementitious material with the objective of disposing the industrial waste sustainably. The usage of complementary cementitious leads to several possible improvements and enhancement in the concrete composites, as well as the overall economy. Ground Granulated Blast Furnace Slag (GGBS) has been constantly in use as cement replacement for sustainable infrastructure. GGBS is a waste product from the iron industry, which can be used as a substitute for cement. GGBS can be used as a substitute cementitious material, reducing cement consumption and reducing cost of construction. The use of industrial waste products saves the environment and conserves natural resources.The partial replacement of GGBS with cement has developed as an important alternative to conventional concrete and has quickly attracted the attention of the concrete industry through its savings in cement, energy savings, cost savings and environmental benefits and socioeconomic. The partial replacement of GGBS as a cementitious material to cement gives high compressive strength, low heat of hydration, resistance to chemical attack, improved workability, and good durability, environment friendly and cost-effective. Now days, iron and steel slag is used in many areas where its unique characteristics can be used effectively. Due to the growing environmental awareness, iron and steel slags are highly regarded as a recycled material that can reduce environmental impacts due to their conservation and the saving of resources. The increase in the demand for concrete ingredients is satisfied with the partial replacement by waste products that are obtained through various industries. Steel Melting Shop (SMS) slag is a waste generated during the production of steel. This waste is disposed in the form of landfills that cause a large amount of land contamination. Therefore, to meet the growing demand to protect the natural environment, especially in construction areas, the need to use this waste is very important. Therefore, replacing some natural aggregates with steel slag would result in considerable environmental benefits. Blast Furnace Slag (BFS) results in production of GGBS which is a by-product of iron industry and have the potential to replace cement in concrete.Thus, this study explores the use of GGBS and SMS slag as partial replacement to cement and coarse aggregate respectively. Further the study is extended by making a plan of residential building on AUTOCAD in which green concrete containing 55% of GGBS and 50% of SMS as partial replacement to cement and coarse aggregate respectively has been executed. The cost analysis of the building is carried out, which has helped in curtailing the cost of concrete by 22.61%.
Utilization of Slags from Foundry Process
Journal of Casting & Materials Engineering
The melting of steel or cast iron is one step of the foundry process. The foundry industry uses different types of furnaces, and metallurgical slags are products of the pyrometallurgical processes defecting in these furnaces. Furnace slag is a non-metallic by-product that consists primarily of silicates, alumina silicates, and calcium-alumina-silicates. As a by-product of the melting process, furnace slags vary considerably in form depending on the melted metal furnace types, and slag cooling method used. Most quantity of slags from the foundry processes are created in a cupola furnace that is used for cast iron production. An electric arc furnace is usually used for steel production, but it can be used for cast iron production as well. Universal use features an electric induction furnace. Slags from the melting processes in a foundry can be in the form of gravel, or the slag from a cupola furnace can be granulated. The utilization of slags from foundry processes is very delimited in Slovakia because of their quantity. This article deals with the possibility of using foundry slag as a binder in civil engineering. A basic property of a binder in civil engineering is its hydraulicity, which can be given by compression strength. Four metallurgical slags were tested. The values of the compressive strength of the slags were low, but addition cement to the slags resulted in a strong increase in the value of the compressive strength.
Potential beneficial uses of steel slag wastes for civil engineering purposes
Resources, Conservation and Recycling, 1991
Large tonnages of slag wastes are produced in the iron and steel industry and space for dumping them has become a problem.-Any means of utilizing the slag would be welcome. Although blast furnace slags are known to be widely used in the manufacture of cement , the use of steel slags for civil engineering purposes has not been given much encouragement in the literature. This communication reports efforts to assist the Nigerian steel industry to ease the problem of waste disposal. An effort has been made to make their slag potentially useful in civil engineering with, hopefully, some revenue earned from the disposal of the now unwanted material.
Archives of Metallurgy and Materials
Blast furnace and cupola furnace are furnace aggregates used for pig iron and cast iron production. Both furnace aggregates work on very similar principles: they use coke as the fuel, charge goes from the top to down, the gases flow against it, etc. Their construction is very similar (cupola furnace is usually much smaller) and the structures of pig iron and cast iron are very similar too. Small differences between cast iron and pig iron are only in carbon and silicon content. The slags from blast furnace and cupola furnace are very similar in chemical composition, but blast furnace slag has a very widespread use in civil engineering, primarily in road construction, concrete and cement production, and in other industries, but the cupola furnace slag utilization is minimal. The contribution analyzes identical and different properties of both kinds of slags, and attempts to explain the differences in their uses. They are compared by the contribution of the blast furnace slag cooled in water and on air, and cupola furnace slag cooled on air and granulated in water. Their chemical composition, basicity, hydraulicity, melting temperature and surface were compared to explain the differences in their utilization.
Impact of Eco Friendly Blast Furnace Slag on Production of Building Blocks
2020
Solid waste management is one of the prime concerns in the world due to ever increasing proportion of non-biodegradable industrial waste product. Blast Furnace Slag (BFS) is one of the largest by products of steel and iron industries which creates scarcity of land filling area due to ineffective reuse and recycle. The use of such substance to create building blocks not most effective makes it economical, however it also enables in decreasing disposal concern. Clay bricks are the oldest walling material of construction industries. Due to preferable mechanical properties bricks are considered as prime source of masonry units that is used as walling material. Conventional clay bricks required burning process known as kiln firing which emits huge amount of CO2 into the atmosphere. World is facing same problem with the production of cement too. The major reasons behind pollution and environment depletion are due to unremitting decay in natural resources caused form deriving of raw materi...
STUDY OF IRON AND STEEL SLAG AS A PRODUCT WITH RESPECT TO PHYSICAL-CHEMICAL PROPERTIES
International Journal of Advanced Engineering Technology, 2017
This paper review the generation of slag from an integrated steel plant; focusing on, slag generated in blast furnace during process of iron making and through EAF / BOF during process of steel making .The slag generated from BF and EAF/BOF are having different characteristic. The different type of slag having different chemical and physical properties, this depends on the chemical properties of input raw material charged in process of iron/steel making and this slag used in different process as raw material. Blast Furnace slag production ranges from about 220 to 370 kilograms per metric ton of pig iron produced; although lower grade ores may yield much higher slag fractions. Steel making process in electric arc furnaces generates up to 15 % of slag, which is, based on its properties, classified as non-hazardous waste. Disposal of such material requires large surfaces and it is rather unfavorable in economic terms.
Due to growing environmental awareness, as well as stricter regulations on managing industrial waste, the world is increasingly turning to researching properties of industrial waste and finding solutions on using its valuable component parts so that those might be used as secondary raw material in other industrial branches. Although metallurgical slag is still today considered waste and is categorized in industrial waste catalogues in most countries in the world, it is most definitely not waste, neither by its physical and chemical properties not according to data on its use as valuable material for different purposes. Moreover, since the earliest times of the discovery and development of processes of iron and other metals production, slag as by-product is used for satisfying diverse human needs, from the production of medicines and agro-technical agents to production of cement and construction elements. This paper demonstrates the possibilities of using slag as one small part of industrial waste arising from the metallurgical processes of iron and steel production. Considering the specificity of physical and chemical properties of metallurgical slags and a series of possibilities for their use in other industrial branches, this paper pays special attention to slag significant trough the history and its using in the road construction.