Density Of Slag Research Articles

Inter-property Correlation of Al2O3-CaO-MgO-SiO2 Quaternary Slag System in Blast Furnace Ironmaking

Exploring the correlation between the density and the thermo-physical properties of the Al2O3-CaO-MgO-SiO2 quaternary slag system is a subject of great interest in the domain of high alumina slag systems. This work attempts to establish correlations between (a) molar volume/density with enthalpy of mixing and (b) molar volume/density with slag viscosity, for the quaternary slag systems. The former is targeted based on existing models to determine the slag density and enthalpy of mixing first and then to develop machine-learning models which can suitably extrapolate the enthalpy of mixing as a function of slag composition, temperature and density. The volume shrinkage and the exothermic enthalpy of mixing between the slag constituent components are correlated in the current work. The later part would involve the conjunction of two hybrid machine-learning models, one for predicting slag viscosity as a function of slag compositions and temperature, and the other which predicts slag viscosity with the incorporation of slag density. The work will facilitate the establishment of two novel quantitative relationships that could provide better insights into the blast furnace quaternary slag systems.

Density and Surface Tension of Slags from the Joint Smelting of Nickel Saprolite and Copper Pyrite Ores

Density and Surface Tension of Slags from the Joint Smelting of Nickel Saprolite and Copper Pyrite Ores

Influence of SiO2‐Adding on the Thermophysical Properties and Crystallization Behavior of Ladle Slags

The thermophysical properties (viscosity, density, and surface tension) of the secondary metallurgical slags with various CaO/Al2O3 ratios (0.56–1.99) and SiO2 (1–20 wt%) contents are investigated. The results show that the addition of SiO2 increases the viscosity of the cleanness and desulfurization slags (CaO/Al2O3 ratios ≥1). In slag with a higher Al2O3 content (CaO/Al2O3 < 1) and constant CaO content, the viscosity shows a first decreased and then increased phenomenon with the addition of SiO2. Moreover, the breakpoints of the viscosity are strongly lowered with the addition of SiO2. Both the density and surface tension of slags show a decreasing tendency with the SiO2 addition. Moreover, the single hot thermocouple technique method is applied to investigate the crystallization process of the slags, and the result shows that with high SiO2 contents, glassy layers are formed on the molten slags.

The effect of mechanical activation duration on the structure and physical properties of titanium slag

TiO2 is popular in modern industries, including dyestuffs, printing, and cosmetics. To convert titanium slag to TiO2 with maximum efficiency, mechanical activation is an important pretreatment step to control the particle size of the titanium slag and the subsequent leaching process. Our study used a planetary high-energy ball mill to wet the titanium slag by mechanical activation for 3, 9, and 15 h to obtain the optimized condition for particle size control of the pretreated titanium slag. The phase composition was characterized by XRD, FT-IR, and Raman spectroscopy. The main constituents of the titanium slag were determined to be rutile TiO2 and Fe3Ti3O10. Calculating the relative intensity showed that some encapsulated phases were opened because of mechanical activation. The weight and density of titanium slag in the same volume increased, resulting in significantly enhanced peaks. The results can greatly improve the efficiency of subsequent titanium dioxide production. A laser particle size analyzer and SEM characterized the mechanical activation product. The results showed that when the mechanical activation duration is 15 h, the titanium slag obtained has a small particle size and a uniform, smaller specific surface area, and narrow particle size distribution. The current report has not introduced wet grinding to pretreat titanium slag. This simple method can be effectively applied to pre-treat titanium slag raw materials.

Effect of Al2O3 and TiO2 on Viscosity, Surface Tension, and Density of Blast Furnace Slag with CaO/SiO2 = 1.13

The influence of Al2O3 in the range of 10–20 mass% and TiO2 in the range of 0.55–5 mass% on the flow behavior, viscosity, density, and surface tension of molten industrial blast furnace slag with CaO/SiO2 = 1.13 is investigated using a high‐temperature microscope, a rotating viscometer, and the maximum bubble pressure method. The measurement results show that Al2O3 acts as a network former in the studied CaO–SiO2–MgO–Al2O3–TiO2 slags. With an increase in the Al2O3 content from 10 to 20 mass%, the viscosity and surface tension of the slags increase and the density decreases. In contrast to Al2O3, the TiO2 acts as a surfactant and network breaker in the range of up to 15 mass%. The addition of TiO2 up to 15 mass% results in a decrease in the viscosity in the liquid‐dominated region and a decrease in the surface tension of the studied slags. Therefore, the density increases with the addition of TiO2 due to increasing molar volume. The behavior of the breakpoint temperature on all the viscosity curves is in complete agreement with the behavior of the flow point temperature and crystallization temperatures of melilite and perovskite.

Exploration of steel slag for thermal energy storage and enhancement by Na2CO3 modification

Development of thermal storage material from recycled solid waste resources can further enhance the economic and environmental benefits of thermal energy storage system. Thermal properties of steel slag as sensible heat storage material are examined and further enhanced by Na2CO3 activation. The steel slag remains stable until 1200 °C in TG-DSC test, and the morphology kept unchanged after 200 thermal cycles (400–900 °C), indicating good thermal cyclic stability. The thermal energy storage density of steel slag is 797.9 kJ·kg−1 (400–900 °C), the thermal conductivity was measured as 0.505, 0.532 and 0.670 W·(m·K)−1 at 25, 250 and 500 °C, respectively. When the steel slag is further modified by Na2CO3, the morphology and phase of the material remained stable, and the DSC curve trend unchanged after thermal cycle. The thermal energy storage density reaches 997.0 kJ·kg−1 (400–900 °C), which is 25.3% higher than original steel slag. Even more, the thermal conductivity is 1.331, 1.323, 0.889 W·(m·K)−1 at 25, 250, and 500 °C, respectively, which is 32.7% higher than that of steel slag. Hence, the thermal properties of steel slag have been significantly improved by the developed Na2CO3 activation process.

Interfacial Behaviour in Ferroalloys: The Influence of FeMn Slag Composition

The present study investigated the interfacial interaction between FeMn alloy and slags of different compositions and basicity from 0.4 to 1.2 in a sessile drop furnace. Interfacial tension between the FeMn alloy and the slags was measured, and the results were analyzed to assess the sensitivity of the applied methodology. The measurement of the interfacial tension was based on combining the results from experiments, multiphase flow simulations in OpenFOAM, equilibrium calculations in FactSage, and calculation of slag density and surface tension based on numerical models. The results demonstrate that the interfacial tension between the FeMn alloy and slag increases with the slag basicity. It was found that the addition of Al_{2}O_{3} to the slag with basicity of 0.8 and 1.2 increases the interfacial tension, while increasing MnO content from 30.0 to 45.0 wt pct does not have any statistically significant influence on the interfacial tension. EPMA analysis of slag and FeMn phases showed that slags at lower basicities and the FeMn alloy form a metal–slag emulsion due to the destabilization of the interface induced by chemical reactions, partial reduction of SiO_{2} in the slag and the mass transfer of Si across the metal–slag interface.

Simulation study on multiphase behavior of gas-metal-slag in the 260t converter

Taking the 260t BOF steelmaking process as the research object, it is of great significance to study the Gas-metal-slag interaction with oxygen lance. In this paper, a 3D mathematical model is established by using fluent. Through changing some physical parameters of lance height and slag, the impact depth, impact cavity area and energy transfer and flow are analyzed. The numerical results show that with the increase of lance height, the diameter of impact cavity in molten steel becomes larger, but the impact depth decreases. When the lance height is 32de, the area of high speed zone in the molten steel pool is the largest, the energy in oxygen jet is mostly dissipated in the process of reaching the slag level, and the kinetic energy obtained by the slag is only about 14% of the kinetic energy of molten steel. With the increase of slag thickness, the depth and area of the cavity decrease, and the flow of molten steel is restrained. The change of slag viscosity and slag density has little effect on the flow velocity. This study can provide reference and guidance for the regulation and control of the process parameters of converter refining.

Совершенствование использования твердого топлива при слоевом способе сжигания

The article presents the results of studies, the purpose of which is to improve the efficiency and quality of using solid fuel in the layered method of combustion in low-power boilers. In order to achieve this, there are considered the tasks of increasing the efficiency of fuel use, reducing atmospheric pollution and improving the properties of slag, simplifying its further processing. The methodology of work is based on the use of active additives applied directly to the burning fuel layer. The action of the additives was determined by the methods of gas analysis and the compilation of the heat balance of the boiler. There have been obtained boiler performance indicators, which prove the effectiveness of the method. Recommendations have been developed for the implementation of the method in the conditions of poorly automated boiler houses with minimal costs for its implementation. Scientific and practical results of the study make it possible to significantly increase the efficiency of boilers, reduce emissions of products of incomplete combustion into the atmosphere, increase the density of slag, and reduce its volume and erosion. An additional positive social effect is an improvement in the working conditions of boiler operators and an increase in the culture of boiler maintenance.

Study on the separation of silicon from refining slag of industrial silicon

During the process of production and refining of industrial silicon, the discharged slag usually contains more than 15 mass% of metallic silicon. However, the separation of silicon from slag is very difficult due to the close density of silicon and slag as well as the high viscosity of slag, which results in the waste of resources. In the present work, the effect of Na2O addition on the separation of silicon from slag is investigated in detail. It is found that the optimum separation condition of slag and silicon is 1723 K reacting for 60 min by adding 10 mass% Na2O to the slag. Viscosity and density are two important factors affecting the separation effect of silicon from slag. The addition of Na2O reduces the viscosity of slag and promotes the separation of silicon from slag. Even if the addition of Na2O will decrease the density of slag which is detrimental to the separation of silicon, the density variation is not the determining factor affecting the separation relative to viscosity. The separation and extraction of metallic silicon from silicon slag is of great significance for improving utilization of resources and reducing environmental pollution.

Simulation of primary breakup of molten slag in the gas quenching dry granulation process

Gas quenching dry slag granulation process is an energy-saving environmental protection method for waste utilization and waste heat recovery of molten slag, and the molten slag is broken up by supersonic airflow into droplets in this process. This paper performed the numerical investigations on the breakup behavior of slag by the coupled level-set and volume of fluid (CLSVOF) methodology and gain a deep insight into the breakup mechanism of the primary breakup and influence of gas Weber number (We) and liquid Reynolds number (Re) on the primary breakup. The results indicated that the primary breakup include flat film breakup and spherical cap film breakup, the both are typical perforation breakup; Aerodynamic force cause K-H (Kelvin Helmholtz) instability, K-H surface waves are the root cause of film breakup; The wavelength and the film thickness decrease with increasing We which is conducive to reducing the ligament diameter; The wavelength and the film thickness decrease first and then increase with increasing Re which is optimum in the range of 1068–1280; The empirical formula of the ligament diameter is obtained. The ligament diameter decrease with increasing airflow velocity and slag density and increase with increasing slag mass flow rate and slag viscosity.

Dynamic properties of steel slag improved with sand–tyre shreds admixture

To achieve recycled use of waste steel slag and waste tyres, it was proposed to incorporate waste tyre particles into waste steel slag and mix with sand to form a new geomaterial. Considering the effects of confining pressure, incorporation ratios of tyre particles and in corporation ratios of sand, the dynamic shear modulus and damping ratio of the new geomaterial were studied by a torsional shear vibration method based on resonance column tests. The specific control density of steel slag combined with different mixing ratios of tyre particles and sand were determined according to the relative density. The relationship between the dynamic shear modulus and the shear strain of the new geomaterial suited the hyperbolic model of Davidenkov. The maximum dynamic shear moduli of the new geomaterial with the tyre particle mixing ratio of 5% reached 166 MPa at the confining pressure of 200 kPa and were close to those of Fujian standard sand. The maximum dynamic shear modulus of the new geomaterial with the tyre particle mixing ratio of 15% was 103 MPa at the confining pressure of 200 kPa and was larger than those of Nanjing fine sand. The minimum damping ratio of the new geomaterial was in the range of 0·21–1·95% at the confining pressure of 200 kPa and was larger than that of the pure steel slag with 0·15–1·2%. These findings showed that the new geomaterial could be applied instead of sand.

Preparation and properties of foam ceramic from nickel slag and waste glass powder

The utilisation of nickel slag and waste glass powder as raw materials for preparing foamed ceramic was studied. The influences of the mixture design and foaming-agent dosage on the properties and microstructures of foamed ceramic were investigated in terms of the density, flexural strength, phase composition and micromorphology. Results showed that incorporating nickel slag improved the flexural strength and uniformity of the pore structure. However, owing to the high density of nickel slag, its excessive usage may impact the development of foamed ceramic density and porosity as a side effect. The Na2CO3 dosage was another crucial factor determining foamed ceramic properties. A nickel slag content of was 20% and a Na2CO3 content of 7% decreased the foamed ceramic density to 0.498 g/cm3, with a corresponding flexural strength of 2.66 MPa and a higher porosity of 80.06%.

Experimental Study on Physical Excitation of Cementation Activity of Lead-zinc Smelting Slag

In recent years, it is a hot research direction to improve the internal structure and properties of smelting slag by physical grinding and to prepare filling cementitious materials suitable for mining. The paper starts from the test of physical and chemical properties of the smelting slag of a lead-zinc mine, the relationship between the density and specific surface area of lead-zinc smelting slag and the different grinding time was obtained by analyzing the chemical elements of the smelting slag filled with lead-zinc, the density and specific surface area of the smelting slag with different grinding time, and the potential gelling activity of lead-zinc smelting slag were effectively evaluated. It provides a theoretical basis for lead-zinc smelting slag as a new filling material for mines.

Experimental Study for Measuring Density of slag melts by An Established Archimedean Double-bob Method

The apparatus of Archimedean double-bob method for practicing accurate was established for density measurements of slag melts. The accuracy of density measurements at room temperature to establish measurements was determined in the following ways. Firstly, the densities of water were measured at 25, 30, 35, and 40 °C. Secondly, the densities of silicone fluids with the viscosities 0.01, 0.999, 4.850, and 29.44 Pa·s were measured at 25 °C. The measured densities have good agreement with the data of water standards with a precision of 0.07% and silicone fluid standards with a precision of 0.16%. The densities of Na2O–SiO2 slag melts with 60, 70 and 80 mol % SiO2 were measured in the temperature range from 1350 to 1500 °C. The density decreases with increasing temperature and increases with increasing SiO2 contents for all compositions. The reproducibility of this work is within the error estimation of density measurements. The density results of Na2O–SiO2 melts with 60, 70 and 80 mol % at 1400 °C show that the measurements data are within 0.23 % of the density values.

Dynamic Shear Properties of Recycled Waste Steel Slag Used as a Geo‐Backfill Material

Waste steel slag is a recycled industrial solid waste and is sometimes used as backfills, but the dynamic shear properties of waste steel slag have not been researched at present. To understand the dynamic shear properties of waste steel slag, the resonance column tests were carried out to investigate the dynamic shear modulus and damping ratio of the steel slag considering the effect of the relative density of steel slag and confining pressure. The maximum dynamic shear modulus was discussed, and the dynamic model of the steel slag was constructed by the Hardin–Drnevich model. The regression analysis of the normalized dynamic shear modulus ratio and damping ratio of the steel slag showed that the dynamic model was very fit for the steel slag. The comparisons of the dynamic shear properties of the steel slag with those of Nanjing fine sand and Fujian standard sand showed that the steel slag had similar dynamic shear resistance to Fujian standard sand and had potential to become a substitute for sand in the practical geotechnical engineering in the future.

Solidification of Calcium Ferrite Melt Using Ultrasonic Vibration: Effect and Mechanism

Calcium ferrite (CF) is a very important binder phase in iron ore sintering processes. To improve the microstructure of CF, power ultrasound was introduced during its solidification process, and the effect of immersion depth of ultrasonic probe (IDUP) on the properties of CF was investigated in detail. The results indicated that the microstructure of CF was greatly refined; the grain size decreased from 2864 μm without ultrasonic vibration to 841 μm with ultrasonic vibration at an immersion depth of 30 mm. Without ultrasonic vibration, the density and compressive strength of CF slag were 3904 kg/m3 and 38.3 MPa, respectively. When the IDUP was increased from 10 to 30 mm, the density and compressive strength of CF increased from 4049 to 4452 kg/m3 and 52.5 to 87.3 MPa, respectively. Further, the reducibility of CF was examined. The reduction time, at the same reduction rate, decreased from 347 minutes without ultrasonic vibration to 200 minutes with ultrasonic vibration at an IDUP of 30 mm. The rate-limiting step was obviously improved, which may be attributable to the grain refinement of CF and composition segregation in the slag. In general, the properties of CF were greatly improved due to the cavitation and acoustic streaming of ultrasonic waves.

Flexural and Shear Behaviors of Reinforced Alkali-Activated Slag Concrete Beams

The material properties of cement-zero concrete using alkali-activators have been studied extensively as the latest response to reduce the CO2 exhaust of the cement industry. However, it is also critical to evaluate the behavior of reinforced concrete beams made of alkali-activated slag (AAS) concrete in terms of flexure and shear to promote the applicability of AAS concrete as structural material. Accordingly, nine types of beam specimens with various ratios of tensile steel and stirrup were fabricated and subject to bending and shear tests. The results show that the flexural and shear behaviors of the reinforced AAS concrete members are practically similar to those made of normal concrete and indicate the applicability of the conventional design code given that the lower density of slag is considered. In addition, a framework using the elastic modulus and stress-strain relation from earlier research is adopted to carry out nonlinear finite element analysis reflecting the material properties of AAS concrete. The numerical results exhibit good agreement with the experimental results and demonstrate the validity of the analytical model.

Slag density and surface tension measurements by the constrained sessile drop method

Density and surface tension of slag are important properties for mineral processing, metal processing, slagging combustion and slagging gasification. In the case of slagging gasification, slag properties will impact the efficiency, reliability, maintenance cost and environmental performance of the process. There are several methods to determine the density and surface tension of slags. A commonly used technique is the sessile drop technique since it allows determination of both the density and surface tension, and can be performed at high temperatures in controlled gas atmospheres. This technique usually requires substrates that provide high contact angles with the samples for accurate results. To circumvent this issue, constrained sessile drops can be used. The limitations and accuracy of the constrained sessile drop technique for slag density and surface tension measurements were evaluated by a series of tests and phase equilibria predictions. Although molybdenum and alumina substrates provide lower contact angles than graphite substrates with the synthetic coal and petroleum coke slags tested, they interact less with the slags and alumina allows for measurements in both oxidizing and reducing conditions. Use of constraining 8mm diameter molybdenum and alumina substrates resulted in greater precision than use of larger constraining and non-constraining substrates. The density of the synthetic coal slag studied is in the range of ∼2.4g/cm3 for the temperature range of 1200–1600°C, in both oxidizing and reducing conditions. Based on measurements with a molybdenum substrate, its surface tension is ∼420mJ/m2 for the same temperature range. Measurements with alumina substrates, in both oxidizing and reducing conditions, yielded similar results above 1450°C, but higher surface tension was observed at lower temperatures. Measurements with real coal slag provided similar results to measurements with synthetic coal slag. In the temperature range of 1530–1630°C, the synthetic petroleum coke slag has a density of ∼2.4g/cm3. Its surface tension is ∼360mJ/m2 in oxidizing conditions and ∼460mJ/m2 in reducing conditions. The surface tension difference is likely due to different phase equilibria with oxidizing and reducing environments, and may be impacted by the presence of solids in reducing conditions.

Estimating the density of molten CaF2-Al2O3-CaO slags based on optical basicity

Slag density is a significant factor in determining the process efficiency of the electroslag remelting (ESR) process, where calcium fluoride (CaF2)-based slag is formed synthetically to refine metal ingots. Although there are some former studies investigating the density of CaF2-containing slags, the prediction models focusing on them are applicable only to some specific systems. The present study aims to build a model to predict density for a wide range of CaF2-containing ESR slags. To investigate density for various slag compositions, CaF2-Al2O3-based and CaF2-Al2O3-CaO-based slag compositions were prepared. Additionally, some minor constituents like FeO, MgO and MnO were added to a 5:3:2 CaF2-Al2O3-CaO slag in order to investigate the effects of these constituents on the slag. The volumes of the prepared slags were measured in a tube furnace at 1450–1550 °C using the sessile drop technique, and their densities were calculated. The results showed that for the slags, density is related to optical basicity, and therefore a prediction model based on an Arrhenius equation was built. The model was tested with data from literature, and its limitations and validity are discussed.