Papers by Keyword: Slag

Abstract: The use of supplementary cementitious materials (SCMs) has revolutionized the construction industry by significantly reducing the carbon footprint, minimizing waste, lowering labor costs, and enhancing both durability and precision in concrete structures. Accurately predicting compressive strength (CS), a critical mechanical property, is crucial for ensuring these structures' optimal performance and reliability. Given the nonlinear behavior of concrete mixtures incorporating fly ash and slag, machine learning (ML) techniques have become increasingly valuable for predictive modeling. This study assesses the performance of four ML models: Multilinear Regression (MLR), K-Nearest Neighbors (KNN), Random Forest (RF), and Random Forest integrated with Particle Swarm Optimization (RF-PSO). By addressing gaps related to compressive strength variability and comparing model performance, the study found that all four models achieved high accuracy in CS prediction, with RF-PSO consistently outperforming others based on multiple evaluation metrics. Visual analysis corroborates the models' effectiveness, highlighting potential advantages such as improved quality control, cost efficiency, enhanced safety, and environmental sustainability. Furthermore, an analysis of the importance of features was conducted to evaluate the contribution of individual variables in developing the RF-PSO model.

Abstract: The scope of generation, accumulation and use of ash and slag waste of thermal power plants in different countries has been analyzed. The results of the study of the phase, mineralogical and chemical composition of ash and slag waste obtained with the dominance of solid and liquid fuel in the energy balance have been presented. It has been shown that the newly formed and previously accumulated ashes and slags of thermal power plants, with their correct and effective use, are a powerful source of expansion of raw materials in various industries. The existing methods of using ash and slag waste, which have been developed based on their mineral composition and the content of trace elements and impurities in them, have been considered. The most effective application of these wastes is in the construction industry, as well as when used as a raw material for obtaining compounds of rare metals, for example, vanadium.

Abstract: This article presents the optimal method of melting the 35XGCL (analog is JIS G 5111) low alloy steel alloy in DSP-2.0 2000 kg electric arc furnace. All the main stages of melting in an electric arc furnace are considered. In addition, analytical data on the study of the slag mode during the fluidization of the alloy are presented. The results of the evaluation of oxygen activity in metal depending on the chemical composition of slag oxidation and reduction cycles in the furnace are presented. Graphs of oxygen activity in the alloy depending on the total amount of iron, silicon, and manganese oxides in the slag are presented. Moreover, the effect of constant and additional deoxidizing aluminum content in the alloy on the impact strength of low alloy steel alloy is presented. The impact strength is improved when the constant aluminum content is in the range of 0.05-0.07%.

Abstract: Mechanical properties of composites produced from the SiC-rich furnace slag using traditional stone and ceramic machining technologies were studied. A non-uniform mixture of coarse monocrystalline SiC grains soaked with Si-metal and glassy oxide phases represented the microstructure of dense monolithic SiC-rich samples. The fracture mechanism of coarse-grained SiC-rich composites was susceptible to the grain size/sample geometry and machining conditions yielding flexural strength in the range of 50-106 MPa and high compression strength of 750 MPa. Despite inhomogeneous macro and microstructure, mechanical and thermal properties are comparable to the traditionally produced siliconized SiSiC ceramics. It opens up the opportunity for the circular economy and value-added recycling of the Si/FeSi industries’ wastes.

Abstract: Wastes from various industrial processes are used in the construction industry in the production of cement composites, for example as a replacement for part of the cement. In addition to contributing to promoting circularity and reducing the carbon footprint, several waste materials have properties that promote improved durability of the resulting composites due to their pozzolanic properties. This paper deals with testing of the pozzolanic activity of selected wastes from local manufacturing processes such as slag, zeolite, microsilica and fly ash using the thermal analysis method (TG/DSC). The highest pozzolanic activity after 2 days was observed for blast furnace slag, however, after 56 days it was recorded for fly ash and ladle slag. Blas furnace slag and microsilica showed very similar pozzolanic activities evaluated by a comparable amount of unreacted calcium oxide of about 35%.

Abstract: Steel slag nanocomposite was synthesized in this study using a solvothermal preparation technique from raw electric arc furnace (EAF) slag. XRF, SEM, FTIR, and UV–Vis spectroscopy techniques were used to characterize the prepared nanocomposite. The XRF result shows a high amount of SiO₂ and Fe₂O₃ constituent in the slag with a small weight percentage of TiO₂. The prepared slag nanocomposite was utilized for methylene blue (MB) dye degradation. The Photodegradation result from the study indicated an optimum degradation efficiency of 77.07 % at a 40 min irradiation time. The effect of pH variation and catalyst dosage on photodegradation was studied. The results reveal that photodegradation of the dye occurs best in an alkaline solution and that increasing the catalyst dosage above the reaction threshold reduces the degradation efficiency.

Abstract: The aim of the contribution is to use metallographic analysis to determine the root cause of the castings’ defects. The paper will show two cases of defects occurring in the ductile iron castings with surface treatment such as galvanizing and painting. Defects were observed on both the inner and outer surfaces of the castings. Light (LM) and electron microscopy (SEM) was used for individual analyses, including measurement of the local chemical composition by the EDS analysis.

Abstract: Concrete is the most important material in building construction. It had been used widely around the world and is made of cement, fine aggregates, coarse aggregates and water. These materials come from natural resources which had a depletion and environmental pollution issues. On the other hand, tonnes of waste are generated around the world especially in developed country which are having rapid industrialization, increasing population growth, technological developments and urbanization. Most of the waste materials from those causes are not recyclable. The methods managing of the waste materials are usually done by dumping in landfills or burning. Thus, in order to overcome both issues, alternative replacements from waste materials can massively give huge differences to the industry that will reduce the usage of natural resources and gives benefits to the industry itself and also to the environment. Studies on waste materials had been conducted by many researchers before. Hence, in this paper, some materials which are coal bottom ash, slag, ceramic waste and glass powder will be discuss as waste materials that have been used from many backgrounds of industries. This paper attempt to summarize the investigation of the following materials as substitution materials in concrete, with the following discussion. The properties such as workability, compressive strength, ductility etc. of these replacement materials are compared with the normal concrete. A lightweight concrete that is safe and eco-friendly will be produced as a construction material. This shows that some of the materials can improve the performance of concrete itself. Thus, this study is crucial in finding the other waste materials that can act as a replacement.

Abstract: The steelmaking process results in the by-product formation of electric arc furnace slag (EAFS). Slag is recovered at two different stages of the steelmaking process, the first recovery is black and the second is white. The present research focuses on the composition differences between the two types of slag from SONASID-Jorf steel in Morocco. A granular separation of the black and white slag was carried out to monitor the chemical and mineralogical composition. XRD and Fourier Transform Infrared Spectroscopy are performed on the samples in this paper. The slags suggest good hydraulic binder properties. It would be useful for research in the field of building materials to correlate the results of the characterization of EAFS with other types of slag with the aim of improving the potential for partial replacement of cement in the matrix. The slag can also be used as binders in mixtures of bio-based building materials. The electric arc furnace slag (EAFS), exhibiting appropriate cementitious activity, can be utilized as mineral admixture in cement and concrete. Black and white slags are studied in this paper in order to determine their characteristics according to their granularity.

Abstract: A 300-metric ton converter in a steel plant in China was studied. The influence of factors such as slag composition and temperature in the smelting process on the dephosphorization effect was statistically analyzed. The dephosphorization ability of slag increased firstly and then decreased with the increase of temperature, basicity and FeO content. Low-temperature, high-basicity and high-oxidizing slag are thermodynamically beneficial to promote the dephosphorization reaction, but the basicity is higher than 4.0, and the temperature is higher than 1640 °C are not conducive to the slag to obtain better fluidity. At the same time, too high FeO content will increase the activity coefficient of P₂O₅, thereby increasing its activity, which is not conducive to the progress of the dephosphorization reaction. As the end point content of carbon decreases, the oxygen content increases and the phosphorus content decreases. A very low carbon content is not conducive to metal yield and temperature control.