Properties Of Slag Research Articles

Experimental research on the dynamic compressive properties of lightweight slag based geopolymer

The present study aims at preparing lightweight slag based geopolymer (LW-SG) and studying its mechanical properties under dynamic and quasi-static loads. Firstly, three LW-SG with different densities were prepared by replacing the slag with expanded perlite (EP). Secondly, the density, wave velocity and pore structure of LW-SG with different EP contents were tested. Thirdly, the mechanical properties under quasi-static and dynamic loads were compared. Finally, the effects of the strain rate and EP content on the mechanical properties and failure modes of LW-SG were discussed. The results showed that with the EP contents increase, the dry density and longitudinal wave velocity gradually decreased, while the porosity increased. In addition, the quasi-static compressive strength and elastic modulus of LW-SG increased with curing ages, but decreased with EP contents increased. The dynamic compressive strength, dynamic increase factor, strain energy density and damaged degree of LW-SG all showed an increasing tendency with the strain rates increase, which exhibits an obvious strain rate dependence. Under the same strain rate, the dynamic compressive strength and strain energy density decreased with the EP contents increase, while the damaged degree increased with the EP contents increase.

Thermo-mechanical behaviour of fly ash-ladle furnace slag blended geopolymer with incorporation of decahydrate borax

This paper elucidates the effect of adding decahydrate borax (1 and 2 wt%) on thermo-mechanical properties of fly ash-ladle furnace slag (FS) geopolymer at 29 °C – 1000 °C. Adding borax improved the compressive strength of unheated (40.5 MPa) and heat-treated (36.9 – 43.1 MPa) FS geopolymers by 8.4% and 21.2%, respectively. The higher crystallinity, incompact microstructure, and the presence of B-bonds and B-crystals contributed to the high-temperature resistance of FS-B geopolymer. The reduced sintering temperature by 75 °C due to addition of borax compared to FS geopolymer improved the thermal stability and structural integrity during high-temperature applications.

Transient Fluctuations in the Composition and Properties of Blast-Furnace Slag

Transient Fluctuations in the Composition and Properties of Blast-Furnace Slag

Study of Synthetic Titania Slags Demonstrating Characteristics Similar to High Titania Ilmenite Slag

The upgradation of the ilmenite ore, using a pyrometallurgy method, is performed using a carbothermic reduction of the ilmenite. A high titania slag is obtained which is used as a feedstock for the TiO2 pigment production. The slag is cooled after tapping in big molds and can take ten days to cool. This cooling method has remained the same since the inception of ilmenite smelting and recently rapid cooling through granulation has been utilized. The work presented in this paper focuses on the microstructural study of the slags that were prepared using different techniques and cooled at different cooling rates. Various analytical techniques, such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and X-ray photoelectron spectroscopy (XPS) were used to exhibit the similarity of these synthetic slags to the properties of high titania ilmenite slag. The slag consisted mostly of pseudo-brookite phase with a M3O5 stoichiometry and smaller amounts of silicate and rutile phase. A glassy phase of silica was observed and most of the impurities were found to be present in the silicate phase. These silica phases were observed to be separate from the pseudo-brookite phase and along the phase boundaries. Micro-cracking of the slag surface, which is the characteristic of the M3O5 phase formed in the ilmenite slag, were observed under the SEM analysis. The XPS analysis revealed that faster cooling does result in lower amount of oxidation but the difference in the TiO2 and Ti2O3 composition can have larger impact on oxidation than the cooling speed.

Marine Geopolymer Concrete—A Hybrid Curable Self-Compacting Sustainable Concrete for Marine Applications

Marine environments are widely addressed as a serious threat to coastal concrete structures due to higher repair and rehabilitation costs. The rising concerns of climate change and related issues also require marine structures to be resilient and sustainable at the same time. Geopolymer concrete has been given more significant consideration as an alternative, reporting better resistance to harsh and hazardous environmental exposure, including sulphate attacks, chloride attacks, and freeze–thaw climates. This study investigated the mechanical properties of fly ash (FA) and ground granulated blast furnace slag (GGBFS)-based self-compacting geopolymer concrete (SCGC), subjected to short term ambient and marine curing conditions. The mechanical performance, inclusive of compressive strength, tensile strength, and modulus of elasticity under three-month marine exposure compared to an ambient environment, indicates that the SCGC mix offered an increase in strength. It is reported that the compressive strength of SCGC increased to the range of 50 MPa after marine exposure in comparison to the 40 MPa strength after 28-day curing. A similar increase in indirect tensile strength and modulus of elasticity were observed for the test specimens, with no signs of leaching of salts under marine exposure. Thus, the current SCGC acts as a sustainable construction material in counteracting the threats of marine degradation in civil structural components.

State-of-the-Art and Analysis of Characteristics, Properties, Significance, and Application Prospects of Metallurgical Slags

The review article is concerned with the modern state, analysis of characteristics, properties, significance, and prospects of the slags’ application, which are wastes of ferrous and non-ferrous metallurgy. The material considers the structure of steelmaking slags, characteristics of steel slags, separation of slags by composition, as well as the world and Kazakhstan experiences of processing them, using environmental safety assessment. The article reviews and studies the methods of slag application in road construction, agriculture, casting technologies, manufacture of Portland cement, clay bricks, green concrete, etc. The article summarizes the practical experience of many scientists’ research in the fields of metallurgical slag applications. The scientific novelty consists in the study of both the world and Kazakhstan experiences in the using metallurgical production slags based on practical data of researchers around the world with the identification of positive and negative properties of various slags under certain conditions. This topic will be of interest of scientists and researchers in the field of metallurgy and materials science. As found based on the obtained data, the extraction of metal from slag significantly reduces the cost; slag is recyclable after recovery of useful metals from it; reduction of slag dumps makes it possible to improve the ecological situation, as well as to free valuable land areas. The issues of identifying the peculiarities of mining and metallurgical industries’ development and fundamentally new directions’ elaboration, as well as unconventional ways of existing production technologies’ improvement require further study.

Ferrochrome Slag characterization and its compatibility with Quarry dust in Flexible pavement

Exhaustion of locally available materials and increasing hauling charges gained the potential for the exploration of cost-effective alternative materials in the construction industry. Broad endeavours have been made over numerous years on the utilization of industrial waste, yet scant exploration is being done on ferrochrome slag. Ferrochrome slag is an industrial by-product obtained from stainless steel production. Several highway laboratory tests on the characterization of ferrochrome slag are carried out, and the physical and mechanical properties of ferrochrome slag are observed to fulfil MoRTH specifications. Deficiency of fines is observed in the gradation of ferrochrome slag, so quarry dust is incorporated for mechanical stabilization. Ferrochrome slag and quarry dust are blended in different proportions to check the gradation suitability as sub-base and base courses in flexible pavement. Modified Proctor Method of compaction is performed for the ferrochrome slag and quarry dust combinations to carry out the California Bearing Ratio (CBR) test at Maximum Dry Density (MDD) and Optimum Moisture Content (OMC). Studies have shown that the combinations of ferrochrome slag and quarry dust in 70/30 and 60/40 proportions are well graded and have reached the required gradation for use as cement-treated sub-base and base layers in flexible pavement.

Quantification and analysis of slag carryover during liquid steel tapping from BOF vessel

ABSTRACT The amount of slag carryover (SCO) during the liquid steel tapping from the basic oxygen furnace (BOF) vessel has been estimated using a thermodynamic model that ensures the matching the predicted bath silicon with that of experimentally measured silicon in ladle furnace. FactSage 6.4 has been used for thermodynamic analysis. A simple correlation has also been established to estimate SCO immediately after the tapping process using the readily available plant data. Viscosity, interfacial tension of the slag, impurities in the liquid steel, and the tapping temperature has been found to have a profound effect on the amount of SCO. The advantage of the present method of SCO estimation compared to the other methods and the industrially viable control measures for minimising SCO is discussed in light of clean steel practices. Further, industry trials have been conducted to validate the control of SCO by tuning the BOF slag properties.

Structural and hyperfine magnetic properties of primary steelmaking slag

Structural and hyperfine magnetic properties of primary steelmaking slag

Predictive models for molten slags viscosity and electrical conductivity based on directed chemical bonds concept

ABSTRACT The effect of the metallurgical slags composition on their physical properties was studied employing the Directed Chemical Bonds Concept (DCBC). It provides an effective concentration and convolution of the ab-initio information on the type of bonds in multicomponent systems. The predictive models for viscosity (lnη) and electrical conductivity (lnχ) of CaF2-Al2O3-CaO slag system have been built. Slag is a crucial part of various metallurgical processes. The electroslag remelting (ESR) is the best example because its efficiency and resulting ingot soundness strongly depend on slag properties. For the two slags (with 1.5 and 3% SiO2), the condition of stable homogeneous structure (activation energies ratio Eη/Eχ ≤1) has been satisfied in the widest temperature range (1513–1773 K) with a suitable viscosity (0.02–0.09 Pa∙s) and electrical conductivity (100–270 1/Ohm∙m). The DCBC makes it possible to move from the empirical selection to the target-oriented design of a proper slag with specific physical properties.

Studying the Slagging Properties of Mechanically Activated Coals

Studying the Slagging Properties of Mechanically Activated Coals

High efficiency desulfurization behavior by the sustainable low carbon utilization of carbide slag

For the purpose of the gradual decrease of calcium carbonate resources and reduction of carbon emissions in wet flue gas desulfurization process, the utilization process of carbide slag to replace limestone is systematically analyzed. The properties of carbide slag and limestone have been analyzed, and the mass transfer and reaction behaviors in desulfurization process have been calculated and comprehensively evaluated. Desulfurization performances have been also compared through response surface analysis method. The results show that the calcium content and specific surface area of carbide slag are higher than limestone, which is conducive to the dissolution and mass transfer rate. Therefore, carbide slag is suitable for the treatment of flue gas with high SO2 concentration. Desulfurization efficiencies of the two desulfurization agents of carbide slag and limestone under the optimal process are 99.15% and 96.53%, respectively. In conclusion, carbide slag can be used in desulfurization process to replace limestone. The consumption of carbide slag slurry in the desulfurization process is about half of limestone slurry at the same conditions, and the higher desulfurization efficiency of carbide slag is attributed to the higher mass transfer and dissolution rate. Utilization of carbide slag also reduces the carbon emission in desulfurization process and economic cost. The reduction amount of CO2 emission can reach to about 0.76 t /t carbide slag. This work provides a basis for the industrial application and desulfurization efficiency improvement of carbide slag as the desulfurizer.

Dissolution behavior of silica in molten CaO–SiO2–Fe2O3–MgO–MnO slag

AbstractThe modification of basic oxygen furnace (BOF) slag by adding silica can improve the properties of BOF slag for applications in the cement industry. The rapid dissolution of silica is essential to hot slag modification. In this work, the dissolution behavior of silica in the molten CaO–SiO2–Fe2O3–MgO–MnO system as synthetic BOF slag was investigated by using the traditional rotating cylinder technique. Effects of rotation speed, temperature, immersion time, and slag basicity on the silica dissolution were studied. Scanning electron microscopy equipped with energy dispersive spectrometer (SEM‐EDS) and FactSage simulations were employed to reveal the dissolution mechanism. It was found that the dissolution of the silica rod was affected by both the thermodynamic driving force and the slag viscosity. The silica dissolution rate in molten CaO–SiO2–Fe2O3–MgO–MnO slag increased with increasing the rotation speed and temperature, but first increased and then decreased when decreasing the slag basicity from 2.5 to 1.5. A linear correlation between the logarithm of the dissolution rate and the logarithm of cylinder periphery velocity with a slope of 0.44 was observed, indicating the mass transfer within the boundary layer as the dissolution rate determining step. A direct dissolution way was found during the dissolution of silica in molten CaO–SiO2–Fe2O3–MgO–MnO slag.

Research Progress on Controlled Low-Strength Materials: Metallurgical Waste Slag as Cementitious Materials.

Increasing global cement and steel consumption means that a significant amount of greenhouse gases and metallurgical wastes are discharged every year. Using metallurgical waste as supplementary cementitious materials (SCMs) shows promise as a strategy for reducing greenhouse gas emissions by reducing cement production. This strategy also contributes to the utilization and management of waste resources. Controlled low-strength materials (CLSMs) are a type of backfill material consisting of industrial by-products that do not meet specification requirements. The preparation of CLSMs using metallurgical waste slag as the auxiliary cementing material instead of cement itself is a key feature of the sustainable development of the construction industry. Therefore, this paper reviews the recent research progress on the use of metallurgical waste residues (including blast furnace slag, steel slag, red mud, and copper slag) as SCMs to partially replace cement, as well as the use of alkali-activated metallurgical waste residues as cementitious materials to completely replace cement for the production of CLSMs. The general background information, mechanical features, and properties of pozzolanic metallurgical slag are introduced, and the relationship and mechanism of metallurgical slag on the performance and mechanical properties of CLSMs are analyzed. The analysis and observations in this article offer a new resource for SCM development, describe a basis for using metallurgical waste slag as a cementitious material for CLSM preparation, and offer a strategy for reducing the environmental problems associated with the treatment of metallurgical waste.

Investigation of cooling processes of molten slags to develop multilevel control method for cleaner production in mineral wool

Direct use of molten slags in production of mineral wool is considered a positive approach for large-scale absorption of this waste, both economically and environmentally. However, this application has been limited by the poor production stability caused by the complex and variable compositions and properties of molten slags. To improve it, this study developed a novel multilevel control method based on molecular dynamics simulations and experimental investigation of structure and thermophysical properties of molten slags during cooling processes over a broad basicity range. The structural analysis showed as the basicity increased, the Si-related network was depolymerized and the Al-related structure was polymerized, and as a comprehensive result the degree of polymerization of melt decreased. The reflection of this structural change on the process properties was the flowing and crystallization abilities of molten slags increased. Especially, the viscous flow activation energy decreased from 188.43 to 185.15 kJ/mol and the critical cooling rate increased from 5 to 30 °C/s. The mineral wool prepared from molten slags with basicity of 0.8 showed the optimal morphology and mechanical properties overall, with the fibrosis rate of 91%, the mean fiber diameter of 5.39 μm, the tensile strength of 2518 MPa. We further analyzed the relationship between structure, rheological and crystallographic properties, and product quality. Based on these, method of determining initial composition, temperature schedule, and cooling rates for cleaner and high-efficient production was developed from the structural simulation, viscosity-temperature curve and time-temperature-transformation curve.

A review of steel slag as a substitute for natural aggregate applied to cement concrete

Steel slag is the main by-product of steelmaking, and its stacking and burying cause serious pollution to soil and water. Meanwhile, the exploitation of gravel is restricted with the implementation of ecological environment protection, resulting in the lack of nature aggregate. Based on the good engineering properties of steel slag aggregate, many researches attempted to substitute natural aggregate with steel slag applied to concrete. Therefore, this article summarizes the composition and properties of steel slag and discusses the effect of steel slag on properties and microstructure of cement concrete. Extensive literatures verify the feasibility of steel slag substituting part of natural aggregate in concrete. Steel slag affects the workability and volume stability of concrete but improves compressive strength, frost resistance and wear resistance, whereas it is controversial in flexural strength and permeability. Finally, the future research trends of concrete with steel slag aggregate are put forward.

Effect of Stress–Strength Ratio and Fiber Length on Creep Property of Polypropylene Fiber-Reinforced Alkali-Activated Slag Concrete

Alkali-activated slag (AAS) is an environmentally friendly green cementitious material that can replace ordinary Portland cement (OPC) and has attracted extensive research by scholars all over the world. However, research regarding its creep performance has been lacking, which in turn affects its further application. The creep of alkali-activated slag concrete is large, and fiber addition has been shown to improve this problem. Polypropylene (PP) fiber has good alkali resistance and is economical. This paper studies the effect of the stress–strength ratio and fiber length on the creep property of PP fiber-reinforced alkali-activated slag (FRAAS) concrete. At the stress–strength ratio of 0.15, PP fiber addition is able to greatly reduce the creep of concrete. When the stress–strength ratio increases, the shorter fiber loses the anchoring force and the holes caused by the longer fiber crack. This in turn leads to the deterioration of the inhibition effect on concrete creep. The CEB-FIP 2010 model is highly accurate, but the final value prediction is small. The early prediction value of the GL2000 model is rather large and conservative. The creep coefficient of the prediction model and the measured secant modulus of PP FRAAS concrete with different fiber lengths under different stress–strength ratios may solve the issue of creep prediction.

Effect of Chemical Treatment on Silicon Manganese: Its Morphological, Elemental and Spectral Properties and Its Usage in Concrete

The effect of chemical treatment on silicon manganese slag and the effect of curing time on the compressive strength of completely replacement coarse aggregate silicon manganese concrete (SMC) relative to normal weight concrete (NWC) with gravel as coarse aggregate is the subject of this paper. Alkali and acidic base chemicals are used to alter the neat silicon manganese slag during chemical preparation. The mixture pattern proportions for Grade 30 and Grade 50, respectively, were used to create the concrete. Before the compressive strength tests, the samples were cast and cured for 7-, 14-, and 28-days. The properties of the silicon manganese slag and its concrete were studied using a scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR). The compressive strength of SMC30 and SMC50 obtained were 37.3 MPa and 51.1 MPa, respectively, on the 28-day. The alkaline treatment smoothest the matrix, while the acid treatment roughens the composition of the silicon manganese slag, according to SEM. The functional group demonstrated a major improvement in FTIR, while EDS revealed a high content of both silicon (Si) and manganese (Mn) elements. As a result, it can be observed that the power of SMC increases as the curing time increases for samples with complete replacement of normal aggregates using silicon slag.

Microstructure Evaluation on Micro and Nano Slag Particles Reinforced AA7075 Composites

The research work was focused on utilization of solid industrial waste. In order to investigate the properties of Fe-Cr slag particulates strengthened AA7075 composites. In this paper addition of ferrochrome slag particles as reinforcement in AA 7075 alloy processed through stir casting technique. By varying size of ferrochrome slag particles were added to evaluate the size effects in the given alloy matrix. Prepared composites were subjected to heat treatment and evaluated for microstructure analysis. The results show that there is a uniform distribution of particles in the matrix and that there is a strong bond between the matrix and the reinforcement. Grain refinement in the alloy matrix is observed by inducing slag particles. Further nanocomposites show lower grain size values.

Chemical Characterization of Slags from an Old Smelter in Chihuahua, Mexico

Slag is waste from pyrometallurgical processing, usually stored in stacks or warehouses around or near smelters. Slag research has focused on potential environmental problems associated with slag weathering or processing for secondary metal recovery and/or other uses (construction, landscaping, etc.). Located in northern Mexico, the city of Chihuahua has a mining history that dates back to the eighteenth century. A lead smelter located southeast of Chihuahua City; closed in 1997, leaving behind a large pile of slag. In this study, a chemical analysis of smelter slag was carried out. The tailings contain Zn (15 - 35 wt%), Pb (0.5 - 4 wt%), As (0.6 wt%), Sn (888 ppb) and Hg (170 ppb). XRD identified several minerals such as hardystonite (Ca2ZnSi2O7), melanotekite (), kentrolite () and sphalerite (ZnS) in the glass. Major elements are present in phases such as monticellite (CaMgSiO4), kirschsteinite (CaFe2+SiO4), hedenbergite (CaFe2+Si2O6), babingtonite (Fe2Si3O9), magnetite (Fe3O4), and calcite (CaCO3). Whether the goal is reuse, recycling or remediation, research into the properties of slag and its environmental and health impacts (on vulnerable exposed populations) should continue to be relevant.