Electric Arc Furnace Slag Research Articles

Determination of the Chemical, Physical and Mechanical Characteristics of Electric Arc Furnace Slags and Environmental Evaluation of the Process for Their Utilization as an Aggregate in Bituminous Mixtures.

Road construction is an activity that demands a significant amount of aggregates for bituminous mixtures. In addition, these aggregates must be of a suitable quality for use, even more so on high traffic roads. In response to this problem, and in order to avoid the extraction of new raw materials, research is being carried out using industrial waste as a substitute for conventional aggregates. In this way, the extraction of raw materials is reduced and landfilling of waste is avoided. However, these wastes must have certain properties and environmental advantages over natural aggregates. Otherwise, the use of waste would not be environmentally beneficial but would be more damaging to the environment. For this reason, this research evaluates the viability of using electric arc furnace slag as aggregates for bituminous mixtures, the main objectives being the determination of the characteristics of the by-product, the particularities and the critical points to be taken into account for its subsequent use in mixtures. At the same time, the environmental advantages of treating this waste to obtain a usable aggregate are evaluated in comparison with the processing of a natural aggregate. The results showed that electric arc furnace slags have a suitable chemical composition and excellent physical and mechanical properties for use in bituminous mixtures, even on high traffic roads. At the same time, it was determined that their use produces a considerable reduction in environmental afflictions. Therefore, it could be affirmed that the use of electric arc furnace slags in bituminous mixtures is recommendable as a way to develop more sustainable materials for construction.

Use of electric arc furnace slag (EAFS) in construction - state of the art

El aumento de la población mundial ha tenido como consecuencia el crecimiento de la industria de la construcción. Lo anterior, implica la explotación de recursos naturales no renovables y por ende un mayor impacto ambiental por la contaminación del suelo, el agua y el aire. Así, el desarrollo sostenible se ha convertido en una prioridad en la industria, por ejemplo, por medio de la incorporación de residuos en la cadena productiva. El acero puede producirse por dos métodos: el alto horno (se funden minerales de hierro) y el horno de arco eléctrico (se funde chatarra metálica reciclada). En este último, el proceso más utilizado en Colombia, se forma la escoria horno de arco eléctrico (EHAE). Este residuo representa una oportunidad de aprovechamiento en la construcción. Varias investigaciones han estudiado el uso de este material como agregado y como materia prima del cemento. Así mismo, su utilización como sustituto de material granular en la construcción de terraplenes, bases, subbases y capas de rodadura, siendo en el área de pavimentos donde mayor aplicación puede darse a la escoria. Este trabajo tiene como objetivo realizar una revisión actualizada del estado del arte sobre el uso de la EHAE en la construcción, para promover la implementación correcta y segura de este residuo y aportar a la sostenibilidad de la industria siderúrgica.

Cohesive zone modeling of EAF slag-included asphalt mixtures in fracture modes I and II

Fracture properties of asphalt mixtures containing fine and coarse Electric-Arc Furnace (EAF) aggregates were determined at low-temperature conditions by implementing Cohesive Zone Modeling (CZM). Semi-Circular Bending (SCB) test was conducted in both fracture Mode I and II (opening tensile and in-plane shear, respectively), and the bi-linear traction separation law was used to obtain the coefficients of cohesive elements. To determine the fracture failure probability concerning the adopted testing parameters, the two-parameter Weibull distribution curve was fitted on the FEM results. Based on CZM simulation modeling, it was observed that the simulated curves were promisingly consistent with the experimental results. Weibull distribution analysis revealed that the inclusion of fine EAF slag aggregates increases the fracture failure probability compared with those containing coarse aggregates. A statistically predictive model was introduced, based on the Weibull distribution results, to predict the in-plane shear (Mode II) fracture properties using those of Mode I.

Study on leaching of electric arc furnace (EAF) slag for its sustainable applications as construction material

The steel production generates approximately 10 % of electric arc furnace slag on the production of each ton of steel. In the view of environmental concerns and government regulations regarding slag disposal, alternate ways of its utilization are required. This work is focused on the leaching behaviour study of electric arc furnace (EAF) slag to assess its suitability as construction material. EAF slag contains toxic metals; consequently, their leachable quantity may affect the eco-system. Chromium (Cr), lead (Pb), mercury (Hg), molybdenum (Mo) and cadmium (Cd) have found special concern due to their high toxicity for human kind as well as for the environment. The leaching study of EAF slag was carried out through the application of sequential batch water leaching tests (SWLT), batch test and toxicity characteristics of leaching procedure (TCLP) method. Fresh EAF slag was characterized by XRF, XRD, SEM and ICPMS analysis for the determination of essential compositions and contamination. SWLT was performed at different pH of 4.0, 5.3, 6.1, 7.2 and 8.5. It was found that toxic metals was not leached beyond permissible limits at any pH. Moreover, TCLP method was applied for the leaching analysis of EAF slag at pH of 4.93 and 2.88. The concentrations of toxic metals in leachates were found negligible through ICP-OES analysis. The batch test method was also applied upto 60 days of EAF slag. This test was carried out at various pH ≈ 4, 5 and 6. The obtained leachates were tested at 10 days, 15 days, 30 days, 45 days and 60 days of leaching. The ICP-OES analysis of leachates showed negligible concentrations of leached metals/elements. Through the application of different leaching test methods, it was found that the leaching of hazardous heavy metals from EAF slag is negligible or within permissible limits as per IS 383−2016 and EPA. Therefore, EAF slag can be utilized as construction material in eco- friendly manner.

Fundamental properties and radioactivity shielding performance of concrete recycled cathode ray tube waste glasses and electric arc furnace slag as aggregates

In this study, cathode ray tube (CRT) waste glasses and electric arc furnace slag (EAFS) were replaced with fine and coarse aggregates to evaluate gamma-ray shielding performance, mechanical performance, and microstructures based on replacement ratios. The results show that as the replacement ratio of a CRT waste glass increased, the volume of pores with diameters ranging from 5 to 200 nm increased. Moreover, the slope of the linear attenuation coefficient of the CRT/EFAS specimen increased with a decrease in the half-value layer, and the greater the energy of the gamma ray, the lower the shielding efficiency of the CRT/EFAS concrete. The compressive strength and flexural strength decreased when the CRT and EFAS were replaced as the aggregate, but the mechanical performance of the CRT/EFAS concrete could be obtained by substituting the mineral admixtures.

Use of Iron and Steel Slags in Concrete: State of the Art and Future Perspectives

In the two last decades, world production of pig iron and steel has undergone a significant increase. In 2018, 1252.87 and 1806.46 million tons of pig iron and steel, respectively, were produced as compared to the 575.78 and 809.94 million tons of 2000. Consequently, the amount of the different types of slags deriving from these production processes has also increased considerably. In relation to the principles of sustainability and circular economy, the available literature suggests several possible reuses for these slags (bituminous conglomerates, hydraulic engineering, metallurgy, fertilizers, etc.). This paper aims to provide an overview of the iron and steel slags production and their reuse in concrete (for example as replacement of cement, fine or coarse aggregates). The characteristics of slags are analyzed in terms of chemical, physical, and mechanical properties. Mechanical and durability tests (both from material and structures point of view) carried out in the different studies and research are shown as well. Particular attention was devoted to electric arc furnace slags (EAF) since they are the most produced in Italy. Based on this deep literature review, the gaps that still require further studies have been identified and discussed.

Development of High Resistance Hot Mix Asphalt with Electric Arc Furnace Slag, Ladle Furnace Slag, and Cellulose Fibers from the Papermaking Industry

Roads are currently essential links of communication and economic development. However, these roads are progressively requiring higher quality materials, implying a greater impact on the environment, in order to withstand the high levels of heavy vehicle traffic. Therefore, this research proposes the use of industrial by-products to create bituminous mixtures which are more resistant and durable than traditional ones. The industrial by-products used, are electric arc furnace slag, ladle furnace slag, and cellulose fibers from the papermaking industry. These by-products were physically and chemically characterized to be used to conform with bituminous mixtures. At the same time, bituminous mixtures were conformed with conventional materials, thus being able to compare the physical and mechanical properties of the conformed mixtures through different tests. The results showed how the use of cellulose fibers made it possible to absorb a greater percentage of bitumen, as well as the use of electric arc furnace slag and ladle furnace slag created mixtures, with greater Marshall stability. Therefore, sustainable, durable, resistant, and high waste mixtures were developed in this investigation.

Bituminous base courses for flexible pavements with steel slags

The purpose of this research was to study the feasibility of incorporating steel slags into coarse bituminous mixtures. The objective was twofold: to reduce dependence on natural aggregates, and to provide a use for industrial by-products. The slags studied come from the manufacture of carbon steel in electric furnaces and are divided into two types: Electric Arc Furnace (EAF) slag and Ladle Furnace (LF) slag. The mixture designed is coarse bituminous concrete (AC22G), for base courses in flexible pavements. In a first phase, the physical characterization of the materials was carried out to check their suitability. In a second phase, three types of mixes were designed: a control mix (made with natural limestone aggregates), a mix where LF slag was introduced to replace the filler and the fine fraction (sand) of the mix; and finally, the feasibility of manufacturing a totally sustainable mix was analyzed, which would fully incorporate EAF slag as coarse aggregate and LF slag as fine aggregate and filler. In a third and final phase, the designed mixes were subjected to different mechanical, water sensitivity, and durability tests. The research demonstrated that the incorporation of EAF and LF steel slag as a substitute for natural aggregate in coarse bituminous mixtures is feasible, meeting regulatory requirements, improving sustainability in the construction industry, as well as reducing emissions, and contributing to climate change mitigation.

COMPRESSIVE STRENGTH OF CONCRETE MADE WITH ELECTRIC ARC FURNACE SLAG AND RECYCLED GROUND GLASS AS REPLACEMENT OF COARSE AND FINE AGGREGATE

Concrete is one of the most studied industrial products with the aim of improving its durability, strength, and workability, as well as developing innovative alternatives in its production to reduce the environmental footprint (Rivera, 2013). This research validates the use of industrial waste generated in the department of Boyacá - Colombia, within the production of concrete for the construction of rigid pavements. The research followed several stages, beginning with the physical, chemical, and mechanical characterization of the materials and the design of the standard mixture following the ACI 211 methodology. Subsequently, the 25%, 50%, 75%, and 100% of the gravel was replaced by electric arc furnace slag (EAFS), and 20, 30 and 40% of the sand by the recycled ground glass (RGG). Finally, the compressive strength of the concrete mixtures was analyzed.

Multiphase phosphate cements from steel slags

The use of industrial waste in the synthesis of phosphate ceramics opens the door to new ways of production and marketing of this kind of product, as well as contributing to the reduction of the environmental impact of industrial waste. In the present study, chemically bonded phosphate ceramics (CBPC) were synthesized from steel slags (electric arc furnace slag (EAF), basic oxygen furnace slag (BOF), and ladle furnace basic slag (LF) and aqueous solutions of H3PO4. A chemical analysis was performed of the steel slags, which were selected through standard sampling before being ground and milled to obtain the appropriate granulometry. In the evaluated slags, iron oxides and calcium oxides, present both in their free state and in compounds with other elements, were identified as the elements with the greatest presence and potential to form CBPC. Design of experiments (DOE) was applied to form multiphase cements, in order to make the variables present in the obtainment of cements workable, thereby allowing the formation reactions of cement to be better understood. The cements obtained were analyzed through XRD, SEM-EDS, FTIR, XPS, and mechanical compressive strength tests. The synthesized cement exhibited mainly vitreous structure for the iron phosphate phases (Fe(H2PO4)2) or (FeHPO4), and mainly crystalline structure for the calcium phosphate phases, present as dihydrogen phosphate of calcium hydrate (Ca(H2PO4)2·xH2O) and brushite (CaHPO4·2H2O). Compression strength between 10 and 19 MPa was recorded for the different compositions evaluated, with short setting times.

Effects of freeze-thaw cycles on the characteristics of the expansive soils treated by nanosilica and Electric Arc Furnace (EAF) slag

The problematic expansive soils are spread in many countries and require significant improvement. The impacts of nanosilica and the Electric Arc Furnace (EAF) slag on the improvement of the swelling potential, volume changes, and Unconfined Compressive Strength (UCS) of the expansive clay samples were experimentally investigated in this study. In addition, the durability of the stabilizers against adverse effects of consecutive freeze-thaw cycles was also assessed using macro and micro tests. The results showed that the expansibility of the soil samples improved by 20% of the EAF slag and 0.5% of nanosilica decreased by 77.5% after one day of curing. To evaluate the durability of the samples, the number of freeze-thaw cycles was repeatedly increased until the dynamic equilibrium was reached. Then, the volume and water content changes and also the strength reduction rate of the treated and untreated samples were measured at the end of each cycle. The results revealed that the dynamic equilibrium for both untreated and treated samples was recorded during the 2nd to 4th cycles. The highest strength reduction rate occurred after the 1st and 2nd cycle and it was respectively 29% and 36% for the untreated and only 14% and 18% for the treated samples by the optimal amount of the EAF slag and nanosilica after 7 days of curing. However, the strength reduction rate decreased to 5.4% and 6.4% after 28 days of curing, thus curing time brought the significant improvement and promising results for the treated samples against the freeze-thaw cycles. In addition, the maximum volumetric strain was measured as 6% for the untreated expansive clay, occurring after the 4th freezing cycle. However, this value decreased significantly to 2.75%, occurring after the 3rd freezing period, for the sample improved by nanosilica and the EAF slag simultaneously. Thus, the results confirmed the strong potential use of the mixture of the EAF slag and nanosilica in reducing the negative effects of freeze-thaw cycles on the soil characteristics. Finally, to identify the underlying improvement mechanisms, the microstructural analyses were also carried out on different soil samples by using the X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) tests.

Mechanical Performance of High-Strength Sustainable Concrete under Fire Incorporating Locally Available Volcanic Ash in Central Harrat Rahat, Saudi Arabia.

This study investigated the effect of elevated temperatures on the mechanical properties of high-strength sustainable concrete incorporating volcanic ash (VA). For comparison, control and reference concrete specimens with fly ash (FA) were also cast along with additional specimens of VA and FA containing electric arc furnace slag (EAFS). Before thermal exposure, initial tests were performed to evaluate the mechanical properties (compressive strength, tensile strength, and elastic modulus) of cylindrical concrete specimens with aging. Additionally, 91 day moist-cured concrete specimens, after measuring their initial weight and ultrasonic pulse velocity (UPV), were exposed up to 800 °C and cooled to air temperature. Subsequently, the weight loss, residual UPV, and mechanical properties of concrete were measured with respect to exposure temperature. For all concrete specimens, test results demonstrated a higher loss of weight, UPV, and other mechanical properties under exposure to higher elevated temperature. Moreover, all the results of concrete specimens incorporating VA were observed before and after exposure to elevated temperature as either comparable to or slightly better than those of control and reference concrete with FA. According to the experimental results, a correlation was developed between residual UPV and residual compressive strength (RCS), which can be used to assess the RCS of fire-damaged concrete (up to 800 °C) incorporating VA and EAFS.

A Case Study of Industrial Symbiosis to Reduce GHG Emissions: Performance Analysis and LCA of Asphalt Concretes Made With RAP Aggregates and Steel Slags

The concept of sustainability in the road construction sector is a complex issue because of the various steps that contribute to the production and release of greenhouse gas (GHG) emissions. Addressing this issue, the European Commission has put various policy initiatives in place to encourage the construction industry to adopt circular economy (CE) and industrial symbiosis (IS) principles e.g., the use of recycled materials. Cooperativa Trasporti Imola (CTI), a company located in the Emilia-Romagna region (Italy), has been chosen for the current case study to examine practices, management, and the industrial symbiosis network among various companies in the road construction and rehabilitation sector. In this regard, the use of steel slags, obtained by an electric arc furnace (EAF), and reclaimed asphalt pavement (RAP), obtained by the deconstruction and milling of old asphalt pavement have been investigated. Two mixtures of recycled hot Mix Asphalt (HMA) i) were prepared incorporating different recycled material percentages for the wearing and binder course, respectively, ii) were characterized in terms of size distribution, strength modulus and volumetric properties, iii) and finally were compared to the performances of two mixtures entirely designed by virgin materials for the wearing and binder course, respectively. Therefore, the Life Cycle Assessment (LCA) tool was chosen to evaluate the environmental impacts that affect the designed road life cycle. The results show that recycling RAP and EAF slags in a CTI batch plant provides benefits by reducing the consumption of virgin bitumen and aggregates and by reducing CO2eq emissions. Finally, practical implications on the use of recycled materials in new asphalt mixtures from a life cycle and industrial symbiosis perspective are provided.

Evaluation of the Use of Electric Arc Furnace Slag and Ladle Furnace Slag in Stone Mastic Asphalt Mixes with Discarded Cellulose Fibers from the Papermaking Industry

The construction sector is one of the most demanding of raw materials that exist at present. In turn, the greenhouse gas emissions that it produces are important. Therefore, at present there are several lines of research in which industrial by-products are incorporated for the manufacture of bituminous mixtures and the reduction of CO2 emissions, framed inside the circular economy. On the base of the aforementioned, in this research, bituminous mixtures of the Stone Mastic Asphalt type were developed with electric arc furnace slag, ladle furnace slag and discarded cellulose fibers from the papermaking industry. To this end, the waste is first characterized physically and chemically, and its properties evaluated for use in bituminous mixtures. Later, different groups of samples are conformed with conventional materials and with the waste in order to be able to compare the physical and mechanical properties of the obtained bituminous mixtures. The physical tests carried out were bulk density, maximum density and void index, as well as the Marshall test for the evaluation of the strength and plastic deformations of all the bituminous mixtures manufactured. The study and evaluation of the results showed that the incorporation of slag makes it possible to absorb a greater percentage of bitumen and obtain better mechanical properties, while maintaining a similar deformation and void content. Therefore, it is feasible to use the mentioned slags to create sustainable, resistant and suitable pavements for important traffic.

A Review of the Influence of Steel Furnace Slag Type on the Properties of Cementitious Composites

The type of steel furnace slag (SFS), including electric arc furnace (EAF) slag, basic oxygen furnace (BOF) slag, ladle metallurgy furnace (LMF) slag, and argon oxygen decarburization (AOD) slag, can significantly affect the composite properties when used as an aggregate or as a supplementary cementitious material in bound applications, such as concretes, mortars, alkali-activated materials, and stabilized soils. This review seeks to collate the findings from the literature to express the variability in material properties and to attempt to explain the source(s) of the variability. It was found that SFS composition and properties can be highly variable, including different compositions on the exterior and interior of a given SFS particle, which can affect bonding conditions and be one source of variability on composite properties. A suite of tests is proposed to better assess a given SFS stock for potential use in bound applications; at a minimum, the SFS should be evaluated for free CaO content, expansion potential, mineralogical composition, cementitious composite mechanical properties, and chemical composition with secondary tests, including cementitious composite durability properties, microstructural characterization, and free MgO content.

RETRACTED: Mechanical properties of EAFS concrete after subjected to elevated temperature

Recycling of materials has become a major interest. Recently, the amount of slag deposited in the storage yard adds up to millions of tons/year leading to the occupation of farmland and serious pollution to the environment. Electric Arc Furnace slag (EAFS) is made at 1500–1650 °C having a honey comp shape with high porosity so it is expected to be good at fire resistance. Using EAFS as a partial replacement of the natural aggregate can be considered a good alternative for sustainable construction because its cost is very low. Although the existence of a high void ratio, this slag showed high compressive strength when using it as a partial replacement of natural aggregate in conventional concrete due to its good strength characteristics. This study investigates the behavior of using EAFS as a partial or fully coarse aggregate replacement by weight with different percentages of 0%, 15%, 30%, 50%, and 100% in concrete when subjected to elevated temperatures. Six groups of concrete mixes were prepared using various replacement percentages of slag exposed to different temperatures of 400 °C, 600 °C, and 800 °C for different durations of 1hr, 1.5hr, and 2hr. Evaluation tests of EAFS performance as a partial or full replacement of natural aggregate in concrete were compressive strength, tensile strength, and bond strength. The steel slag concrete mixes showed weak workability lower than the control mix. A systematic increase of almost up to 21.7% in compressive strength, and 66.2% in tensile strength with increasing the percentage of EAFS replacement to 50%. The experimental results showed that EAFS enhances the concrete properties and the fire resistance as confirmed by Thermal Gravimetric Analysis (TGA). The high void ratio and the slag components are the causes of this fire resistance enhancement result in improving the durability of concrete.

Analytical study on the behaviour of beam-column joints made of electric arc furnace concrete

The advancement of the construction industry towards using recycled materials has substantially reduced the consumption of natural resources. Electric Arc Furnace (EAF) slag is the by-product obtained from the production of steel and is procured after the separation of molten steel from impurities. In this paper, the impact of EAF concrete on the structural behaviour of beam-column joints and the resisting mechanism of these joints are evaluated using ANSYS software. One joint made with conventional concrete and two joints made with EAF concrete were analysed subjected to incremented loading. The results indicate that EAF concrete exhibits better structural performance than conventional concrete in terms of the ultimate load attained by the joint in the failure condition.

A sustainable solution for ceramic and steel wastes in Self-consolidating, high-performance concrete

This study aims to investigate the applicability of using waste materials produced in Kuwait as partial replacements of conventional concrete materials in self-consolidating, high-performance concrete. Processed ceramic products, along with steel slag obtained from electric-arc furnaces, were used as partial replacements of coarse and fine aggregate at various dosages. The fresh and hardened properties of the concrete were then measured and compared. Results have shown that using crushed ceramic products (in the form of sand-like and 3/16” aggregates) increases the rate of strength gain as the concrete cures, while using electric-arc furnace slag to replace 3/8” aggregates increases the compressive strength when compared to a benchmark mix.

Assessment of Electric Arc Furnace (EAF) Steel Slag Waste’s Recycling Options into Value Added Green Products: A Review

Steel slag is one of the most common waste products from the steelmaking industry. Conventional methods of slag disposal can cause negative impacts on humans and the environment. In this paper, the process of steel and steel slag production, physical and chemical properties, and potential options of slag recycling were reviewed. Since steel is mainly produced through an electric arc furnace (EAF) in Malaysia, most of the recycling options reviewed in this paper focused on EAF slag and the strengths and weaknesses of each recycle option were outlined. Based on the reports from previous studies, it was found that only a portion of EAF slag is recycled into more straightforward, but lower added value applications such as aggregates for the construction industry and filter/absorber for wastewater treatments. On the other hand, higher added value recycling options for EAF slag that are more complicated such as incorporated as raw material for Portland cement and ceramic building materials remain at the laboratory testing stage. The main hurdle preventing EAF slag from being incorporated as a raw material for higher added value industrial applications is its inconsistent chemical composition. The chemical composition of EAF slag can vary based on the scrap metal used for steel production. For this, mineral separation techniques can be introduced to classify the EAF slag base on its physical and chemical compositions. We concluded that future research on recycling EAF slag should focus on separation techniques that diversify the recycling options for EAF slag, thereby increasing the waste product’s recycling rate.

Improvement of a hydrometallurgical process for recovering Mn from electric-arc furnace slag

Electric-arc furnace (EAF) slag is a waste generated in large quantities by the steelmaking industry. This waste contains high levels of Ca, Fe, Mn and Si. In the present study, an improved hydrometallurgical process was demonstrated for efficient recovery of Mn from EAF slag. Firstly, the EAF slag was dissolved in a mixture of nitric and hydrochloric acids to remove the insoluble Si-containing mixture. The generated leaching acid contained 6 g/L Mn, 26.9 g/L Ca, 15.9 g/L Fe and small amounts of other impurities. Secondly, Ca precipitated into anhydrite when concentrated sulphuric acid was added, and the residual Ca ion concentration was 213 mg/L. Thirdly, after Ca was precipitated, nearly 100% Fe was removed as hematite nanoparticles with 67.7% of Fe during the hydrometallurgical processes by adding methanol at an Mmethanol/Mnitrate ratio of 0.75, the retention rate of Mn was higher than 98.5%. Without adding methanol, only 54.8% of Fe was precipitated as an irregular hematite block. Fourthly, the residual Mn content is 5.8 g/L, which was recovered as hausmannite with Mn content of 60.3% when solution pH is adjusted to 8. Hydrolysis of Fe was not observed at 80 °C but accelerated when temperature was higher than 140 °C. Ethanol exhibited removal efficiency of Fe similar to that of methanol, but the optimal Methanol/Mnitrate molar ratio was 0.3, which was 2/5 that of methanol. By using the improved method, high-purity hausmannite product and hematite by-product were effectively recovered from the EAF slag without generating secondary waste.