disadvantages of steel slag

These different types are referred to as furnace or tap slag, raker slag, synthetic or ladle slags, and pit or cleanout slag. These results show that ROWs are decomposed to low-molecular-weight compounds after the pile temperature is elevated and the presence of slag enhances the polycondensation of these compounds to produce HAs with a higher degree of humification. The use of slag in concrete has several benefits, including reduced energy, reduced greenhouse gas emissions, and reduced use of raw materials. The predominant compounds are dicalcium silicate, tricalcium silicate, dicalcium ferrite, merwinite, calcium aluminate, calcium-magnesium iron oxide, and some free lime and free magnesia (periclase). Why is Type IV cement rarely produced and Type V cement rarely used. Microscopic analysis shows that adding a suitable. Average critical temperature values (melting behavior) of the slags before and after foaming practice. It is important to take into account that in order to enhance the performance of this industrial practice, it is necessary to understand deeply the associated fundamental phenomena. To avoid volumetric instability of the cement material, MgO content is determined. As the slag is finely grounded, it has the valence to fill the pores efficiently, workability is high and bleeding is low. Email Address is required These materials must be source separated, and well-defined handling practices must be in place to avoid contamination of the steel slag aggregate. Publishing on IntechOpen allows authors to earn citations and find new collaborators, meaning more people see your work not only from your own field of study, but from other related fields too. Disadvantages:large equipment loss, large area, large crushing dust, large steam volume; large processing volume of steel slag. Steel slag, a by-product of steel making, is produced during the separation of the molten steel from impurities in steel-making furnaces. the hydration process if slag is an exothermic process, thus the generation of heat of hydration is slow. The water was added to the compound and stirred with a glass-stirring rod until dissolved. Steel has very small resistance against fire as compared to concrete. Slag fluidity and the physics and chemistry of the refractory-slag interaction are relevant to the design of these coating slags. The free lime in steel slags can combine with water to produce calcium hydroxide (Ca(OH2)) solution. The lab consisted of two parts. Therefore, accurate viscosity values are essential for the optimization and improvement of metallurgical processes. The tufa precipitates associated with steel slags are attributed to the leachate combining with atmospheric carbon dioxide. Greater persistence and reduced penetrance due to fineness. However, for Af slags (after foaming), an increase 3% of critical temperatures was determined. In this chapter, viscosity values of end-of-blow slags were estimated taking into account the Urbain model and applying the viscosity module for melts of FactSage 7.2 software [6]. Lais Lorena Queiroz Moreira, Leonardo Theodoro Bll and Table 18-3 lists some typical mechanical properties of steel slag. Next, The flame test required the solution made during the solubility test. To control foam height, carbonaceous particles can be added to slag with adequate size and low volatile content. Table 18-3. At the end of the refining operation, the liquid steel is tapped (poured) into a ladle while the steel slag is retained in the vessel and subsequently tapped into a separate slag pot. The size of the bubbles determines the foam behavior. Different steel plants, depending on their lay out, process conditions, and operation, have developed and implemented various techniques for protecting MgO-C refractory lining: brick patching, gunning, manual splashing, chemical splashing, slag coating, slag foaming, and slag splashing [1, 4]. (1,2) The free lime hydrates rapidly and can cause large volume changes over a relatively short period of time (weeks), while magnesia hydrates much more slowly and contributes to long-term expansion that may take years to develop. Steel slag destined for use as an aggregate should be stockpiled outdoors for several months to expose the material to moisture from natural precipitation and/or application of water by spraying. Characterization of humic-like acids produced from humic precursors. All these factors lead to/foster the achievement of a good slag layer on the surface of MgO-C bricks. This is because of the presence of free lime and magnesium oxides that have not reacted with the silicate structures and that can hydrate and expand in humid environments. Slag foaming is also applied in EAF to prevent the heat loss and to decrease the refractory wear. Epub 2020 Mar 12. Wood can suffer from fungal attack; it also decays, and suffers from insect attacks while steel mainly suffers from corrosion. In Table 4, results of the chemical characteristics of carbonaceous materials are informed. The most recent thrust is on more integrated green manufacturing and more intensive waste recycling for sustainable development. This problem can be solved to some extent using anti-corrosion applications. Slags of appropriate characteristics allow lining recovery, reducing corrosion damage, oxidation, and erosion of the refractory, as well as the impact of the charge, without altering the metallurgical function of the BOF. Would you like email updates of new search results? However, slags with higher FeO content promote the increase of the liquid phase proportion (L1) with chemical composition changes that produce disadvantages regarding wettability. (1): where is the viscosity in poise; T is the absolute temperature in K; and A and B are the parameters that depend on slag chemical composition (A is expressed in poise K1 and B in K), Eq. At 1600C, the average of the contact angle measured was average=33. [21] informed that concrete with crystallized slag sand addition presents good physical and mechanical properties. Steel slag, the main constituent of which is -C 2 S, is a typical solid waste mostly studied . Please enable it to take advantage of the complete set of features! Ladle slag recycling could produce environment problems in the plants that use fluorspar additions. So that resistance against severe conditions increases. Blast furnace ironmaking is inseparable from the coke source, but the coke resources are getting less and less, but the price is getting higher and higher, the cost of iron making will be higher and higher, and it is likely that one day will meet the depletion of coke resources. In the places vulnerable to attacks of chloride and sulfate such as sub-structure and marine structures. As professional one-stop solution provider, LIAONING MINERAL & METALLURGY GROUP CO., LTD(LMM GROUP) Established in 2007, and focus on engineering research & design, production & delivery, technology transfer, installation & commissioning, construction & building, operation & management for iron, steel & metallurgical industries globally. 2012 Jan;104:497-502. doi: 10.1016/j.biortech.2011.11.021. - Air-cooled blast-furnace slagThe material resulting from solidification of molten blast-furnace slag under atmospheric conditions; subsequent cooling may be accelerated by application of water to the solidified surface. London, SW7 2QJ, The timing for adding steel slag affected the degree of humification of HAs in the composts. Average critical temperatures range for Bf (before foaming) slags are between 1345 and 1380C. Accelerated swelling tests were conducted to evaluate the swelling behavior of pure steel slag and SS treated water treatment residual (WTR), an alum . The use of blast furnace slag as artificial rocks is also possible because they are similar to semi-hard stones. Date:11/30/2022, Publication:Materials Journal Ivanka Netinger Grubea, . Steel slag is residue from the steelmaking process, made of minerals like silica, alumina and titanium from iron sand, and combinations of calcium and magnesium oxides. It is important to mention that during the last year, large thermodynamic databases of multicomponent oxide systems have been developed, and parameters have been optimized in order to reproduce all reliable experimental data within experimental errors. . In Figure 2, it is possible to evaluate the impact of slag FeO content on the viscosity evolution. The processing of steel slags for metals recovery is not only important to remove excess steel at the market source for reuse at the steel plant, but is also important to facilitate the use of the nonmetallic steel slag as construction aggregate. Slag foaming constitutes another alternative to use the converter slags to protect MgO-C bricks below the trunnion line [8, 10]. The use of steel slag as an aggregate is considered a standard practice in many jurisdictions, with applications that include its use in granular base, embankments, engineered fill, highway shoulders, and hot mix asphalt pavement. These impurities consist of carbon as gaseous carbon monoxide, and silicon, manganese, phosphorus and some iron as liquid oxides, which combine with lime and dolime to form the steel slag. Through this process I am refined further to remove any other impurities because I must be at least 99% pure lead. Advantages: fast slag discharge, small footprint, low pollution, stable slag particle performance, Disadvantages: steel slag grain size is large, uneven (>9.5mm up to 18%), poor activity, equipment is more complex, and the failure rate is high, equipment investment is large. Linz-Donawitz (LD) slag, solid waste produced during steel manufacture in basic oxygen furnace, is difficult when it comes to handling and disposal and has very limited utilization. Disadvantages of Structural Steel Structures. In this area of research, it has been concluded that slag is suitable for use in concrete under normal enviromental conditions and has more fire resistance than the commonly used aggregate, but when combined with Portland cement, slag does not provide increased fire resistance to concrete. This chapter is focused on the chemical composition, structural characteristics, thermal and physical properties, and behavior (at high temperature) of different slags used to protect refractories in BOF and EAF as recycling possibilities. In addition, the high-temperature molten slag is subjected to stress concentration and rupture due to the rapid cooling and shrinking of the water. Carbonaceous materials also exert an effect in the foaming practice; it is possible to recommend the addition of petroleum coke (material C3) in the foaming practice, because of its ash low content, high proportion of large pores, and higher carbon content. Developed countries are now laying tremendous emphasis on: (a) reduction in energy consumption per ton of steel produced and (b) sustainable environmental management. The steel slag produced during the primary stage of steel production is referred to as furnace slag or tap slag. To avoid volumetric instability of the cement material, MgO content is determined. When it came to separating the contaminants, the wood and plastic were taken out through the use of tweezers, while the rocks were separated by decanting the mixture of sand and rocks from the water. The study confirms the viability of producing steel-reinforced concrete with slag aggregate (Arribas, Vegas, San-Jose, & Manso, 2014 ). The melting behavior was determined by hot-stage microscopy (HSM). The most commonly used alkaline activators are sodium hydroxide, potassium hydroxide, sodium water glass, and potassium water glass. In the case of basic slags, the authors propose to modify the surface of the aggregates by blending them with a slurry mixture of fine quarry dust and cement in order to avoid the expansion and to reduce the porosity. All contents of this website are copyrighted by LMM GROUP and may not be reproduced in any form without permission. 48331-3439 USA This result is consistent with the %Ash experimentally determined. It is normally agreed that the cementitious properties of steelmaking slag increases with its basicity. Enhanced humification by carbonated basic oxygen furnace steel slag--II. PMC This information represents a good starting point to optimize the BOF foaming industrial practice. Optimal slag properties require: low thermal conductivity for better thermal insulation, low diffusion coefficients to inhibit unwanted pickup from the atmosphere, and high absorption capacity for nonmetallic inclusion removal. The amount of ladle slag generated in the steelmaking is important. Finally, lumps of slags could be added in BOF to improve dephosphorization. Typical physical properties of steel slag. We do OEM for Concast and Danieli for a long time. 8600 Rockville Pike The heat retention characteristics of steel slag aggregates can be advantageous in hot mix asphalt repair work in cold weather. The solid phases include 2.66 g of MgO and 0.44 g of Fe (bcc). Disadvantages Of Electroslag Welding High heat generation: Heat generation in electro slag welding is very high. Finally, the corrosion of the steel rebars in the reinforced EAF slag concrete, after a year in the tidal seawater environment, showed greater susceptibility to corrosion than in the limestone reference concrete. The presence of impurities and possible reactions between the crucible material and the slag produces a transportation problem in the interface that can reduce the values of the properties and can occasionally modify wettability. Influence of iron oxide content on viscosity at 1600C. The timing for adding steel slag affected the degree of humification of HAs in the composts. The Offices 2 Building, One Central The cooling rate of steel slag is sufficiently low so that crystalline compounds are generally formed. Efforts are on for economic use of all types of steel plant wastes, such as slag, dust, and flue gases [1]. The practice is carried out with nitrogen injection through a lance at different heights. In this sense, understanding the properties of slags is a prerequisite to apply them in different functions. Fax: 1.248.848.3701, ACI Middle East Regional Office The pain reliever used is aspirin and the antacid used is baking soda. Date:9/1/2022, Publication:Concrete International Phone: +971.4.516.3208 & 3209, ACI Resource Center It is important to note that sulfur additions suppressed slag foaming and tended to increase the size of CO gas bubbles. Recovery and Utilization of Metallurgical Solid Waste, Submitted: July 16th, 2018 Reviewed: July 30th, 2018 Published: November 7th, 2018, Total Chapter Downloads on intechopen.com. Uneven particle size (>9.5mm up to 29%)[/vc_column_text][/vc_column][/vc_row]. Because of the deliberate hydration procedure, the slump retention and initial setting time are further. However, nowadays three main types of ladle slag recycle products are used depending on the particle size and chemical composition: (a) desulfurizing agent in hot metal pretreatment, (b) as a product to substitute converter flux, and (c) as a product to substitute ladle flux. Slag processors may handle a variety of materials such as steel slag, ladle slag, pit slag, and used refractory material to recover steel metallics. Unable to load your collection due to an error, Unable to load your delegates due to an error. This is affected by the concentration of surfactants and the chemical activity of the surface active component, which determines the surface active concentration in the surface layer [15]. Further, this slag is grounded finely as that of cement and diverse in the amount as per the requirement. Are you have a purchasing plan contact us to get best plan. Chemical and mineralogical composition of Portland cement. In this study, Eq. In agreement with BOF foaming practice, the rate of gas generation was found to be an important parameter in carbon-slag interactions and needs to be optimized to maintain optimum levels/duration of gas entrapment by the slag and foaming behavior. This is explained by the higher chemical interaction in contact with the slag, due to the reduction of the oxides present in the ash and FeO content. One of the main applications that can be given to the slag is as recycled aggregate in the formulation of concrete or abrasive material applications. - Expanded blast-furnace slagThe lightweight, cellular material obtained by controlled processing of molten blast-furnace slag with water or water and other agents such as steam, compressed air, or both. The slag occurs as a molten liquid melt and is a complex solution of silicates and oxides that solidifies upon cooling. Collins, R. J. and S. K. Ciesielski. The applications of steel slag powder and steel slag aggregate in ultra-high performance concrete (UHPC) were investigated by determining the fluidity, nonevaporable water content, and pore structure of paste and the compressive strength of concrete and by observing the morphologies of hardened paste and the concrete fracture surface. Phone: 1.248.848.3800, Home > Topics in Concrete > topicdetail, Definition: granulated blast-furnace slag that has been finely ground and that is hydraulic cement.- ACI Concrete Terminology, Publication:Materials Journal Samitinjay S. Bansode, in Characteristics and Uses of Steel Slag in Building Construction, 2016 4.6 Slag applications in road constructionpavement structure. BOF-converter slags are also applied in buildup, foaming, or slag splashing practices carried out to prolong the lifespan of refractory lining. Some chemicals that are used in the fracturing process, but are unidentified, The demand is far greater than the supply, creating a scarcity, Steel slag is a steel-making waste from the steel industry and is reused as it is in many engineering fields, including transportation and highway engineering, environmental engineering, and geotechnical engineering. Before At initial stages of the blow, a slag with high viscosity could generate small bubbles with a resistant liquid film and the foam will be more stable. To summarize, slag recycling requires the availability of detailed and precise information on their behavior, physical properties, and structural characteristics. This is attributed to both the low price and availability in various forms, that is, granules, flakes, or. Epub 2008 Aug 8. The blowing practice, the end of blow temperature, the ratio of solid-to-liquid phases in the slag, its morphology, its particle size, and chemistry are determining factors for the required properties. In this chapter, two main slag practices are described: slag coating and slag foaming considering experimental data and theoretical information. Senani et al. It is possible to reduce steelmaking cost and get ecofriendly benefits, recycling ladle slag. Tufa precipitates have been reported to clog drainage paths in pavement systems.(5). Furthermore, the 250-mL beaker was weighed, and its mass was recorded. These steel refining processes give rise to another type of slag, called "Ladle Furnace Slag" (or "LFS"), in a range of approximately 30-80 kg per tonne of refined steel. Epub 2011 Nov 16. Slag foaming height is well connected to carbon injection rate and slag chemical properties. As PhD students, we found it difficult to access the research we needed, so we decided to create a new Open Access publisher that levels the playing field for scientists across the world. The capacity of graphite to reduce wear is based upon its large wetting angle for oxide melts. This type of slag may represent a good alternative to reduce the cost of cement production, contribute to environment protection, and provide enormous social and economic benefits. Not only does the slag foaming practice protect the equipment covering the arcs and the refractory lining (the furnace roof and sidewalls from excessive heating and radiation), but it also reduces the arc noise, decreases electrode and electricity consumption, and has present a significant impact on improving thermal efficiency. Steelmaking slag added into ladle slags makes it possible to minimize slag line wear. Zhang X, Zhao Y, Meng H, Li L, Cui H, Wei Z, Yang T, Dang Q. J Agric Food Chem. View all Frequently Asked Questions on slag in concrete», The Role of Silica Fume in Reducing the Carbon Footprint of Concrete, *2022 Slag Cement in Sustainable Construction Awards, Young Professional Receives Free ACI Convention Registration, The Quest for Carbon-Neutral Concrete Part 2, The Quest for Carbon-Neutral Concrete Part 1, Charles K. Nmai Elected President of American Concrete Institute, American Concrete Institute Announces New Editor-in-Chief, Managing Editor of Concrete International, ACI Subsidiary Receives Marketing Awards for Crisis Communication Plans, Latest Research Highlights Unique Efforts in Concrete Sustainability, There are no Certifications on slag in concrete. They have high bulk specific gravity and moderate water absorption (less than 3 percent). Blast Furnace Slag Cement (Application, Pros & Cons). The iron and steel slag used as aggregates for asphalt roads are iron and steel by-products. However, it is relevant to highlight that ladle slag reuse promotes dephosphorization reaction at BOF and can substitute expensive steelmaking agents, and besides, the process can be more ecofriendly. The injection of oxygen and carbonaceous materials in industrial EAF furnaces creates highly dynamic and nonsteady state conditions. Slag recycling in the steel job constitutes a relevant way of reusing with important economic impact on refractory costs. The reaction between FeO present in the slag and carbon is strongly endothermic. Up to 18 months may be needed to hydrate the expansive oxides. . Typical mechanical properties of steel slag.(3). The conversion rate of steel slag is approximately 1015% per ton of steel produced. Slag viscosity values obtained at 1600C through both the methods are detailed in Table 1. There is a wide variation in the amount of time required for adequate exposure to the elements. Surface tension consists in a physical property that depends principally on the surface and not on the bulk. It is important to highlight that the foaming index decreases as the size of carbonaceous particle increases. These different slags must be segregated from furnace slag to avoid contamination of the slag aggregate produced. Blast furnace slags cooled in air constitute a crystallized material used as raw material instead of sand in the production of concrete. A lot of research has focused on the reuse of blast furnace slag to make building materials. The material must not present reactions or composition changes greater than 1% in a period of 100years. Steel slag is a byproduct of iron and steel production by the metallurgical industries. [3] described two possible methods to recycle ladle slag: (a) by pouring molten ladle slag to another ladle, at time (taking advantage of the heat) and (b) by making a ladle slag ingot. Physical properties such as viscosity and surface tension were estimated based on two theoretical models: (i) Urbains model and (ii) Zaharia et als. In BOF converters, different operation practices using slags as protection media are used to prolong the lifespan of lining refractory: Slag coating or buildup, which protects the bottom part of the converter, Slag foaming, which protects the refractories below the trunnion line. Ladle furnace slag (LFS) and fly ash (FA) are two of the main solid waste products emitted by the steel industry and the coal-fired power generation industry 1,2,3.About 20-25 billion tons of . Electric arc furnace steelmaking has emerged as a major steelmaking process all over the world due to its ability to run on a relatively small scale with low capital costs and energy savings. (2). This site needs JavaScript to work properly. Date:7/1/2022, Publication:Concrete International Steel is an alloy of iron. * Hardness of dolomite measured on same scale is 3 to 4. During ladle refining, additional steel slags are generated by again adding fluxes to the ladle to melt. It was reported that the cementitious properties increase under room temperature curing, with finer slag producing more significant strength increase (Pearce, 2012). Next, a 100 mL graduated cylinder was used to measure 60 mL of distilled water. Arcelormittal, TATA Steel, EZZ steel etc. Slag samples, obtained pre (Bf) and post (Af) foaming practice, were characterized. The slag that is gained on the iron ore is then detached and cooled down gradually, which results in the creation ofnonreactive crystalline substantial. The foamy slag provides an insulating layer to the melt, thereby reducing energy loss. Various types of slag are produced: The melting behavior was determined by hot-stage microscopy (HSM). Fig 1: Extraction of molten Slag from Blast Furnace. The worlds largest tubular mold (2201250) was poured successfully! Transient foams last for a few seconds, while stable foams have prolonged shelf life [12]. The morphology, the phases present, and the porosity of the carbonaceous particles were studied by light and scanning electron microscopy including EDS analysis. Due to this property, this type of cement can be used where the problem of thermal cracking is foreseen. Question: Why is Type IV cement rarely produced and Type V cement rarely used? JEGEL. The https:// ensures that you are connecting to the Table 18-2 lists the range of compounds present in steel slag from a typical base oxygen furnace. The Urbain model [5] classified the oxides into three groups: Modifiers: XM=XCaO+XMgO+XNa2O+XK2O+3XCaF2+XFeO+XMnO+2XTiO2+2XZrO2. . Can only handle liquid slag, Process characteristics and process: Compressed air is used as a cooling medium to rapidly cool, reform and granulate liquid steel slag, Advantages: safe and efficient, fast slag discharge, mature technology, small footprint. Next comes the refining process. Do you add scrap or hot metal to the converter first? MgO content in the slags mentioned is between 7.2 and 12.4%. FeO content in the slag constitutes a variable that enables to control slag foaming. Then, the pipet was rinsed with distilled water. The former method of recycling ladle slag is pouring the molten slag from a ladle to another or making ladle slag ingot [3]. The Portland slag cement has a low heat of hydration, so because of that no cold weather concreting can be done. This is the major source of steel slag aggregate. A slag sample with FeO18, MgO11, CaO43, Al2O31.6, and SiO217%wt. Before setting up a model for disruption in steel slag concrete, it is necessary to consider an important point: concrete is a structurally . An official website of the United States government. The chemical and mineralogical composition of Portland cement is detailed in Table 5. The slag occurs as a molten liquid melt and is a complex solution of silicates and oxides that solidifies upon cooling. Figure 18-1 presents a diagram of the general flow and production of different slags in a modern steel plant. Slags can penetrate the bricks only when the graphite is burnt away near the hot face owing to diffusion of oxygen in between flows during a campaign [1]. A new concept considers to use the waste of one industry as a resource in another industry. As it is known, converter slags are an extremely complex mix of oxides that determine the slag physical properties such as viscosity, density, surface tension, and others. This potentially expansive nature (volume changes of up to 10 percent or more attributable to the hydration of calcium and magnesium oxides) could cause difficulties with products containing steel slag, and is one reason why steel slag aggregates are not suitable for use in Portland cement concrete or as compacted fill beneath concrete slabs. Natural graphite, on the other hand, produces excellent slag volumes but slow reduction of iron oxide. A lance is lowered into the converter and high-pressure oxygen is injected. Date:2/23/2023, Publication:Materials Journal Noureldin, A. S., and R. S. McDaniel. We do OEM for Concast and Danieli for a long time. Steel slag is mildly alkaline, with a solution pH generally in the range of 8 to 10. The content of %FeO in these four slags is between 22 and 30% and of %MnO between 5.4 and 8.3%. During the steelmaking process, slags float on top of the molten iron, forming a . We are a community of more than 103,000 authors and editors from 3,291 institutions spanning 160 countries, including Nobel Prize winners and some of the worlds most-cited researchers. Process characterization and the role of inorganic components in the formation of humic-like substances. This operation is called ladle refining because it is completed within the transfer ladle. The bicarbonates reacts with hydrogen ions from citric acid to form carbon dioxide gas and water. - Granulated blast-furnace slag (GBFS)The glassy granular material formed when molten blast-furnace slag is rapidly chilled, as by immersion in water. The results were correlated with the information of the slag characterization. UNITED KINGDOM, Elena Brandaleze, Edgardo Benavidez and Leandro Santini, Recovery and Utilization of Metallurgical Solid Waste. Land and marine applications include seaport and airport civil engineering projects, coastal protection structures, seaweed bed rehabilitation, and land surface coverage [22]. During slag foaming, when carbon is injected into the slags, gas bubbles are formed around the carbonaceous particles. In this chapter, results of 16 BOF slags characterized for foaming practice are informed. There are multiple components that make an alka-seltzer dissolve. Thus, HAs were extracted from the prepared composts and the humification parameters were determined, in terms of elemental compositions, acidic functional group contents, molecular weights, spectroscopic parameters from UV-vis absorption and 13C NMR spectra.

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