The share of continuous casting method is increased day by day among steel production methods. In continuous casting plants, steel production is carried out using BOF (basic oxygen furnace) or EAF ...(electric arc furnace). During the journey of the liquid steel through whole steelmaking stages, the carryover ladle slag can turn into one of the most detrimental element in casters. It is known that a carryover ladle slag consists of mainly oxides such as CaO, SiO
2
, Al
2
O
3
, and MgO. Carryover slag has to be kept under control otherwise one can end up with negative results. With the development of sensor technology, the detection of carryover ladle slag becomes possible at the end of heats. The main advantage of the sensor type is early detection over a human-controlled system. A few seconds can make a big difference on safety, quality, yield, castability, and cost when the casting sequence lengthens due to the amount of slag. Nowadays, steel production via BOF which is performed with very low profit margins makes it important to solve this problem. Especially steelmaking produced by BOF, the detection methods of carryover slag are human controlled, electromagnetic based, ultrasonic based, image processing based, acoustic based, and vibration based. In this study, it is seen that the vibration-based detection system has many advantages over others when considering investment cost, product quality, castability, and accuracy. The scope of the study aimed to design a vibration-based carryover slag detection system on BOF steel production line. The designed detection system has an accelerometer, data processor, and controller system. After the experimental study, the cost, the product quality, and the productivity analyses were performed for the condition of use and non-use of the vibration-based detection system. At the end of this study, it is seen that the vibration-based carryover slag detection system is affordable and feasible.
High-Performance Concrete (HPC) meets special requirements (e.g., low shrinkage and permeability, high strength, and improved durability) and uniformity requirements beyond the range of conventional ...concrete. Self-compacting Concrete (SCC) is placed by its weight as it is enough flowable to pass through congested reinforced areas and avoid aggregate segregation. To reduce cement use and the associated CO2 production from its production, Ladle Slag, a steel industry waste material, is used to replace cement in the production of HPSCC. The material's chemical composition indicates self-cementing and pozzolanic properties. Ladle Slag (5%, 10%, 15% and 25%) is used in place of CEM I (cement) and their fresh, mechanical and durability properties are compared with the control concrete (no waste) sample. The fresh properties were tested and confirmed using Slump flow, T 500, V-funnel, and L-box. Obtained results generally indicate improvement in fresh, mechanical and durability properties of produced concretes for up to 15% use of Slag compared to the control concrete. Cost analysis suggests that industrial waste could be a promising green material for HPSCC by economically saving the carbon footprint.
•High performance and self-compacting concrete using industrial waste.•Limited studies used ladle furnace slag in high-performance SCC as Supplementary Cementitious Materials.•With no processing cost, ladle slag HPSCC up to 70 MPa compressive strength was achieved.
Ladle slag, a byproduct of steel manufacturing, exhibits inherent reactivity and undergoes hydration when exposed to water. Nevertheless, these reaction byproducts often remain metastable, leading to ...microstructural alterations when incorporated into cementitious materials, thereby limiting the recycling potential of ladle slag. This study explores the fire insulating capacity and the physical, mechanical, and leaching characteristics of gypsum-based materials with substantial quantities of ladle slag in instead of gypsum. The mechanical strength of the specimens declines as the ladle slag content increases. Nevertheless, the percentage decrease in compressive strength at various temperatures (300 °C, 500 °C, and 700 °C) is less pronounced when higher amounts of ladle slag are used. Fire-resistant properties, assessed using the EN 1363-1 standards, diminish with increasing slag proportions; although the inclusion of ladle slag introduces certain endothermic processes that positively affect the fire insulating capacity, resulting in a 20% reduction when 60%wt of slag is employed. Notably, no gas emissions were observed during the fire test, indicating the absence of environmental hazards. In conclusion, ladle slag does not pose a leaching threat to the environment, making it a viable and sustainable alternative to gypsum in gypsum-based materials.
Some laboratory experiments are carried out to investigate the reaction between manganese steel and ladle slag. It is found that as expected when the slag basicity R = w(CaO)/w(SiO2) is sufficiently ...low, for example, R < 4, the dissolved Al in conventional Al‐killed steel could reduce the SiO2 component of the slag. In the case of manganese steel grades w(Mn): 6–20%, w(Al): 0.025%, the reduction of SiO2 by dissolved Mn becomes much more profound compared with that by dissolved Al, resulting in the increase of MnO in slag. When the Mn content is high enough, for example, w(Mn) = 20%, the reaction between the MgO in slag and the dissolved Mn in steel is also very evident. High slag basicity can restrain the reduction of SiO2 by dissolved Mn, but the reaction between MgO and Mn can still take place to generate MnO in slag. High‐basicity refining slag (R > 4) is recommended for manganese steel grades.
Laboratory experiments are carried out to investigate the reactions between manganese steel and ladle slag, and the significant reactions are discussed. The remarkable reaction between the MgO in slag and the dissolved Mn in steel is newly found in the case of high Mn steel grades. Suggestions are also given to the slag of manganese steel grades in industry.
In this study, the properties of immobilization of metal(loid)s in artificially contaminated dredged sediment using various binders (gypsum, DAP, and ladle slag) are reported. The effects of binders ...on the immobilization were evaluated by chemical leaching tests such as US EPA Toxicity Characterization Leaching Procedure (TCLP), Korean Standard Leaching Test (KSLT), Potentially Bioavailable Sequential Extraction (PBASE) and The Standard, Measurements and Testing Programme of European Union (SM&T). The results of TCLP and KSLT extraction showed that Pb and Zn concentrations in dredged sediment were highly reduced after immobilization with ladle slag and DAP. The gypsum was ineffective. However, As concentration in the dredged sediment immobilized with DAP increased because of the competition between arsenate and the phosphate originated from DAP. The increased immobilization efficiency is attributed to the increase in the step 3 & 4 fractions of PBASE and SM&T extraction. Among the binders, the ladle slag was the best efficiency in the metal(oid)s immobilization. As the water content and wet&dry cycling period increased, the TCLP-extracable concentration decreased. The Hazardous Index of CSOIL model for the aqua regia digestion, PBASE and SM&T in the immobilized dredged sediment with ladle slag were lower than metal(loid)s concentration of dredged sediment, respectively, under the non-residential and residential scenarios. KCI Citation Count: 0
The purpose of this study was to investigate the mechanism causing the unsoundness of ladle slag. Calcination temperature may have an impact on the level of reactivity of f-CaO. When CaO was produced ...at a higher temperature, the reactivity of CaO was lower. For example, dead burnt CaO (DCaO) was produced at higher temperatures than light burnt CaO (LCaO); therefore, DCaO had less reactivity than LCaO. In a hydration test, DCaO (1500 °C) showed 62 times lower reactivity than LCaO (900 °C), which meant that DCaO would result in the delay of hydration of CaO easily. Additionally, DCaO would cause unsoundness more easily than LCaO when adding the same number of cementitious materials. For this reason, using ASTM C114-18 (Standard Test Methods for Chemical Analysis of Hydraulic Cement) to quantify DCaO content may underestimate DCaO content by up to 20%. Conversely, this method was more suitable for f-CaO since it had high reactivity. Moreover, this study demonstrated that ladle slag would cause unsoundness when added into the cementitious material because it was produced from a higher temperature process (over 1500 °C), which generates the DCaO. Therefore, when reusing ladle slag, the problem of low reactivity of DCaO should be considered.
The sustainability of resources is becoming a worldwide concern, including construction and building materials, especially with the alarming increase rate in global population. Alternative solutions ...to ordinary Portland cement (OPC) as a concrete binder are being studied, namely the so-called alkali-activated cements (AAC). These are less harmful to the environment, as lower CO2 emissions are associated with their fabrication, and their mechanical properties can be similar to those of the OPC. The aim of developing alkali-activated materials (AAM) is the maximization of the incorporated recycled materials, which minimises the CO2 emissions and cost, while also achieving acceptable properties for construction applications. Therefore, various efforts are being made to produce sustainable construction materials based on different sources and raw materials. Recently, significant attention has been raised from the by-products of the steelmaking industry, mostly due to their widespread availability. In this paper, ladle slag (LS) resulting from steelmaking operations was studied as the main precursor to produce AAC, combined with phosphating bath sludge—or phosphate sludge (PS)—and aluminium anodising sludge (AS), two by-products of the surface treatment of metals, in replacement rates of 10 and 20 wt.%. The precursors were activated by two different alkaline solutions: a combination of commercial sodium hydroxide and sodium silicate (COM), and a disposed solution from the cleaning of aluminium extrusion steel dies (CLE). This study assesses the influence of these by-products from the steelmaking industry (PS, AS and CLE) on the performance of the alkali-activated LS, and specifically on its fresh and hardened state properties, including rheology, heat of hydration, compressive strength and microstructure and mineralogy (X-ray diffraction, scanning electron microscopy coupled with energy dispersive spectroscopy and Fourier transform infra-red. The results showed that the CLE had no negative impact on the strength of the AAM incorporating PS or/and AS, while increasing the strength of the LS alone by 2×. Additionally, regardless of the precursor combination, the use of a commercial activator (COM) led to more fluid pastes, compared with the CLE.
The article presents results of examining of hydraulic properties of ladle slags formed during production of steel. The studied ladle slags were subjected to different cooling mode from the molten ...state. Based on the ability of the slag react with the water was assessed their hydraulic activity. The hydraulic properties are caused by the presence of minerals dicalcium silicate, tricalcium aluminate, mayenite, brownmillerite and dicalcium ferite. The emergence of required hydrating phases in the ladle slags is conditioned by a sufficient CaO content and their cooling rate. The contact the slag with water during processing and their ageing has a negative effect. The experiment has shown that the phase transformation of the mineral dicalcium silicate which occurs during cooling of the ladle slags cause their volume instability.
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