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The viscosity of CaO–SiO2–FeOt–Al2O3–BaO steel slag with the BaO substitution for CaO is measured. Calculation of the corrected optical basicity and the apparent activation energy of the steel slag are executed. The effect of substituting CaO with BaO on structure evolution is studied. The measured results show that the viscosity of molten slag increases with the BaO substitution. The values of corrected optical basicity decrease from 0.63441 to 0.62329 with the BaO substitution. The apparent activation energy shows an upward trend from 152.78 to 160.62 kJ mol−1 with the BaO substitution. The Fourier transform infrared reflection analysis indicates that the structure complexity of the [SiO4] and [AlO4] tetrahedrons is increased with the BaO substitution. The Raman analysis indicates that the translation of Q0 and Q1 to Q2 and Q3 is advanced with the substitution of BaO for CaO in molten slag. The conversion of O2− to O0 is promoted with the substitution of BaO for CaO using X‐Ray photoelectron spectrometer analysis. The complexity of the molten slag network structure and the degree of polymerization are all increased by the substitution of BaO for CaO, which sits comfortably with measured viscosity results. [ABSTRACT FROM AUTHOR]

In this study, the wetting and corrosion behavior of slags containing vanadium (V) and titanium (Ti) on the oxidized surface of MgO–C refractory (MO), were investigated. The microstructures and phase compositions were analysed at the interface between the slag and MO substrates, alongside an examination of the corrosion mechanism. The findings unveiled that adding V2O3 and TiO2, whether individually or in tandem, reduced the slag's melting point and the contact angle between the slag and MO substrate. The molten slags mainly penetrated the MO substrates through pores, cracks, and grain boundaries, forming silicate, and vanadate phases at the slag–MO interface. In particular, the V–containing slag demonstrated stronger susceptibility to corrode the MO substrate due to the capacity of V to form low–melting point phases with MgO. This led to deeper penetration and a larger corroded area within the substrate. These findings offer valuable insights for the design and optimization of slags containing V and Ti and MgO–C refractory materials in metallurgical processes. [ABSTRACT FROM AUTHOR]

The present study investigates the wetting and corrosion behaviour of slags on dense Al2O3 ceramics, focusing on the influence of varying vanadium- and titanium oxide content. Physicochemical properties of the slag were assessed by measuring wetting angles, heights and diameters of the molten slags on the alumina at different temperatures. Microscopic observations and elemental composition analysis were conducted on the interface between the corroded Al2O3 ceramics and the slags. Our findings demonstrated that the V2O3 addition in the slag leads to its oxidation to V2O5, which further reacts with Fe2O3 and MnO to form low melting point phases such as FeVO4 and MnVO6. Consequently, the melting point of the slag decreases significantly, resulting in a decreased wetting angle with the Al2O3 ceramics. The presence of unsaturated alumina in the slag leads to the dissolution of aluminium ions from the ceramics into the slag, which reacts with Fe2O3 and MnO to form spinel phases, contributing to material loss of the ceramics. Infiltration of the slag into the Al2O3 predominantly occurs through the alumina grain boundaries. Two types of infiltration are identified: one involving reactions with alumina to form low melting point phases like Fe2O3 and the other involving inherent low melting point phases such as MnVO6. In contrast, the penetration of SiO2 into the alumina substrate is limited. Additionally, the dissolution of Al2O3 into the slag creates pathways for further infiltration. This study highlights the significant influence of Ti and V content on the physicochemical properties of the slag and provides insight into the corrosion mechanism of Al2O3 ceramics by Ti and V containing slags.

Molten slag has different properties depending on its composition. The relationship between its composition, structure, and properties has been the focus of attention in industrial manufacturing processes. This review describes the atomistic scale mechanisms by which oxides of different compositions affect the properties and structure of slag, and depicts the current state of research in the atomic simulation of molten slag. At present, the research on the macroscopic properties of molten slag mainly focuses on viscosity, free-running temperature, melting point, and desulphurization capacity. Regulating the composition has become the most direct and effective way to control slag properties. Analysis of the microevolution mechanism is the fundamental way to grasp the macroscopic properties. The microstructural evolution mechanism, especially at the atomic and nanoscale of molten slag, is reviewed from three aspects: basic oxides, acidic oxides, and amphoteric oxides. The evolution of macroscopic properties is analyzed in depth through the evolution of the atomic structure. Resolution of the macroscopic properties of molten slag by the atomic structure plays a crucial role in the development of fundamental theories of physicochemistry. [ABSTRACT FROM AUTHOR]

Centrifugal granulation is one key step to enable waste heat recovery from the molten slag in the iron and steel industry. Yet, it remains unknown about the granulation characteristics of molten slag with different chemical compositions, especially at high throughput. In this work, we provided an experimental study on centrifugal granulation with four types of molten slags. The stage-specific centrifugal granulation was recorded and analyzed at first. Both effects of atomizer configuration and chemical compositions on granulation were investigated in detail. The cup-type atomizer favors film-mode disintegration and possesses better anti-adhesion capacity although the final granule size was not strongly affected by the atomizer configuration. Most importantly, centrifugal granulation has been demonstrated with appreciable adaptability to composition-specific blast furnace (BF) slag with binary basicity of 0.9–1.3. The present study not only sheds light on the modest effect of the chemical composition of molten slag on centrifugal granulation characteristics, but also gains credit for the adaptivity of CGATER.

Effect of MgO content on wetting and corrosion behaviour of corundum substrate by CaO–SiO2–MgO (−15%Al2O3) molten slags was investigated at 1450°C via joint application of a sessile drop technique, SEM–EDS detection and FactSage thermodynamic software. All slags exhibit good wettability on the substrate, and the contact angle values are small. Increasing MgO content from 7% to 9% in CaO-SiO2-MgO slags can increase the contact angle between the droplet and the substrate, while the substrate dissolution thickness and the slag penetration depth tend to decrease. Increasing MgO content from 8% to 15% in CaO-SiO2-MgO-15% Al2O3 slags can also increase the contact angle, but significantly decrease the slag penetration depth. The indirect dissolution thickness increases instead due to the formation of a large amount of MgAl2O4 by the interface reaction. The wettability can give an indication of the slag penetration depth in the substrate but not the dissolution thickness of the substrate. [ABSTRACT FROM AUTHOR]

The viscosity of steel slag plays an important role in mass transfer, steel-slag reaction rate and slag discharge. The viscosity of CaO–SiO2–FeOt–(Al2O3)–BaO slag with different Al2O3 content was measured. The effect of Al2O3 on structure evolution was investigated. The results showed that the viscosity of steel slag increased by the addition of Al2O3. The FTIR and Raman analysis all showed that the structures of [SiO4] symmetric tetrahedron and [AlO4] asymmetric tetrahedron were more complex by the addition of Al2O3. The XPS analysis the showed that the overall relative fraction of O0 increased from 34.72% to 38.05%, O- decreased from 55.55% to 54.07%, and O2- decreased from 9.73% to 7.88% with the Al2O3 content from 0% to 6wt%. The above analysis meant the degree of polymerization (DOP) increased by the addition of Al2O3, which are agree well with the results of viscosity measurement. [ABSTRACT FROM AUTHOR]

The viscosity of steel slag has an important influence on phosphorus mass transfer in dephosphorization process and slagging-off after dephosphorization. In current work, the viscosity of steel slag was measured and the influence of BaO on viscosity and structure evolution of steel slag was studied. The results showed that the viscosity of steel slag decreased with the addition of BaO. The Fourier transform infrared spectroscopy (FTIR) analysis showed that the degree of polymerisation (DOP) of steel slag is reduced by the addition of BaO. The Raman spectra quantitative analysis revealed that the convertion of Q² and Q³ to Q0 and Q¹ was promoted by the addition of BaO. The X-ray photoelectron spectroscopy (XPS) analysis indicated that the general relative fraction quantity of O0 decreased and that of O2- increased with the addition of BaO. The above analysis are agree well with the results of viscosity measurement. [ABSTRACT FROM AUTHOR]

The entrained flow gasification has been identified as the most promising gasification technology. Serious environmental pollution and waste of land resources are caused by the increasing amount of storage and production of coal gasification slag. The aim of this work is to explore the feasibility of high-temperature combustion and melting technology for treating coal gasification fine slag and determine the important parameters of system operation. The flow properties and molten slag structure characteristics of three fine slags from different entrained flow gasifiers were studied. Depending on the melting mechanism of melt-dissolution, the melting time of fine slags is short. Three fine slags all produce glassy slags, which is conducive to slag discharge. The degree of polymerization of silicate melt is proportionate to the amount of SiO2 in the slag. A part of Al3+ exist in the form of [AlO4]5− because of the effect of CaO and Na2O, as the network former. Finally, the degree of polymerization of the three type molten slag was calculated by considering the role of Si and Al in molten slag and the property of each one. [ABSTRACT FROM AUTHOR]

Molten slag has different properties depending on its composition. The relationship between its composition, structure, and properties has been the focus of attention in industrial manufacturing processes. This review describes the atomistic scale mechanisms by which oxides of different compositions affect the properties and structure of slag, and depicts the current state of research in the atomic simulation of molten slag. At present, the research on the macroscopic properties of molten slag mainly focuses on viscosity, free-running temperature, melting point, and desulphurization capacity. Regulating the composition has become the most direct and effective way to control slag properties. Analysis of the microevolution mechanism is the fundamental way to grasp the macroscopic properties. The microstructural evolution mechanism, especially at the atomic and nanoscale of molten slag, is reviewed from three aspects: basic oxides, acidic oxides, and amphoteric oxides. The evolution of macroscopic properties is analyzed in depth through the evolution of the atomic structure. Resolution of the macroscopic properties of molten slag by the atomic structure plays a crucial role in the development of fundamental theories of physicochemistry.

Traditional methods of disposing of oil-based drill cuttings do not provide the much-needed benign treatment. In this study, a skid-mounted thermal plasma processing device was developed with a designed maximum processing capacity of 0.8 kg/min. When the input power of the plasma torch is 10–50 kW, the temperature measured by the thermocouple is 385–1979 °C. After plasma treatment, the morphology of oil-based drill cuttings changes from jelly-like to vitreous state solid structure, and the content of organic matter decreases with the decrease in weight. Mass and volume reductions of 40.98–61.49% and 25.02–68.81%, respectively, were achieved in a treatment period of 0.5–3 min. The total organic compound reduction of 73.08–98.12% was equally achieved in the same treatment period. Due to the special structure of the glassy state residue, the leached concentration of toxic metals is far below the Chinese standard for landfill leachate discharge. This effectively solves the problem of secondary pollution of solid waste. Therefore, thermal plasma technology is an effective alternative method to treat oil-based drill cuttings. [ABSTRACT FROM AUTHOR]

Approximately 35 % high-temperature waste heat in the steel industry is carried by blast furnace slag and steelmaking slag, and thermal radiation is a primary pathway for this waste heat to dissipate into the ambient environment. Thermophotovoltaic (TPV) systems can convert short-wavelength thermal radiation into electrical energy, but the long-wavelength radiation is still wasted. Here, this work introduces a concept of spectral-splitting (SS) for full-spectrum thermal radiation utilization, allowing simultaneous waste heat recovery by TPV and heat-to-power methods such as Stirling engine (SE). To further demonstrate this concept, an SS TPV-SE system is designed. An optical transmission window of 0–1.7 μm is applied for TPV, and an over 5 μm absorption window is applied for SE. Results show that, with a 0.1 × 1 m molten slag chute, the SS TPV-SE system yields an output power of over 1300 W and achieves an overall efficiency of around 19 %, resulting in an about 58 % improvement compared to the standalone TPV system, and leads to a CO 2 emission reduction of 7516 kg/year. Provided the improved energy efficiency and environmental sustainability, the spectral-splitting concept presented in this work provides a promising approach to enhancing waste heat recovery in the steel industry. • A novel concept of spectral-splitting and cascade utilization of thermal radiation is introduced. • A SS TPV-SE structure for waste heat recovery in steel industry is developed and evaluated. • Numerical simulations are performed to optimize the operating parameters of the SS TPV-SE system. • A comparison is conducted between the SS TPV-SE system and existed WHR methods in terms of efficiency and output power. [ABSTRACT FROM AUTHOR]

• The interaction behavior of slag-iron-carbon multiphase flow has been investigated. • The wetting behavior of molten iron on the graphite is controlled only by its own carbon content. • The wetting behavior of slag on the graphite is influenced by both the carbon content of the molten iron and the composition of the slag. • The reduction ability of dissolved carbon is significantly stronger than that of solid carbon. The interaction between molten slag, liquid iron, and carbon is one of the most typical and complex multiphase flow behaviors in the high-temperature zone of blast furnace. The wetting behavior among these phases is the most fundamental characteristic that determines their interactions. This research focuses on the co-wetting behavior of molten slag and iron on graphite, using high-temperature experiments and atomistic simulations. The results revealed that the multiphase cooperative reaction wetting process is influenced by multiple factors. The wettability of molten iron is mainly affected by its initial carbon content, while the wettability of slag is influenced by both the initial carbon content of the molten iron and its own compositional changes. The initial carbon content in molten iron affects the carburizing reaction, which in turn influences the wetting mechanism between molten iron and graphite. Additionally, it alters the reaction of FeO in the slag, thereby modifying the properties of the slag-carbon interface and affecting the overall co-wetting process. Meta-dynamic calculations showed that the reduction of molten iron oxide by dissolved carbon is significantly more effective than that by solid graphite carbon, demonstrating that the behavior of carbon between iron and slag is a key factor in the multiphase cooperative reaction process. [ABSTRACT FROM AUTHOR]

Many kinds of refining processes are used in the steelmaking industry. Molten metal contained in the bath of the processes is strongly agitated by gas injection. Meal droplets are carried up into the upper molten slag layer due to the gas-lift effect. Each metal droplet falls and finally returns to the lower metal layer although it is captured for a while at the metal-slag interface due to the interfacial effect. The behavior of molten metals near the interface is closely associated with the refining efficiency and metal loss. The residence time at the interface was investigated in this study. An analytical equation was derived for the residence time and a water model study was carried out to validate the equation. Water and silicone oil were used for the models of molten metal and slag, respectively. [ABSTRACT FROM AUTHOR]

It remains a longstanding challenge to recover the waste heat from molten slags in pursuit of lower energy and carbon intensity in the metallurgical industry. To tap the heat from molten slag, the enabling technology i.e. centrifugal-granulation-assisted thermal energy recovery (CGATER) has been proposed and evolved from the laboratory concept into technological embodiment. Further development and deployment of CGATER necessitate a thorough, informative understanding of the multiscale CGATER physics; this is often enabled by modelling. Yet, the availability of informative CGATER physics is very limited due to the insufficiency and complexity of CGATER models. It is thus nontrivial to understand the current CGATER models and most importantly, the challenges and opportunities in future CGATER development. Herein, we first introduce the fundamental physics of CGATER. Second, we provide an overview of the CGATER models in the recent decade. Finally, we further analyze the missing pieces in current CGATER models and suggest future development of the CGATER models. According to the authors' opinion, revisiting current CGATER models is essential. In the future, joint efforts from academia and industry are advocated to develop multiscale, multiphase CGATER models which are expected to accelerate the large-scale implementation of CGATER in the metallurgical industry. • This work provides the most complete summary of the CGATER models. • The complexity of multiscale CGATER physics is elaborated with viable solutions proposed for the multiscale problems. • The gap between the CGATER modelling and CGATER experimental trials is stressed. • New perspectives for future research directions are highlighted towards the industrial-scale CGATER practices. [ABSTRACT FROM AUTHOR]

This paper presents the scientific and technological principles of electrochemical removal of diffusible hydrogen by reactions of hydroxyl and hydrogen in molten aluminum fluoride slag and in the gas phase. A model was proposed for the electrochemical processes in the weld pool with the formation of aluminum fluoride polymer clusters in TiO2–CaF2–Na3AlF6 slag to reduce the content of diffusible hydrogen, decrease the volume of slag inclusions, and improve the mechanical properties of bainitic steel welded joints. [ABSTRACT FROM AUTHOR]

Hydroponic farming promotes high-efficiency water, fertilizers, and high productivity under a controlled environment. However, the use of this system needs consistent application of fertilizers, increasing the cost of operations. Molten Slag (MS), a waste from the Municipal Solid Waste Incineration has essential nutrients that can be used as fertilizer. The objective of this study was to clarify the releasing process of nutrients by molten slag to be applied as a substrate in hydroponic system. For this, anion and cation contents of three varieties of Molten Slag (MS1, MS2, MS3) were determined in the laboratory by a shaking method. The nutrient content, P2O5, K2O, MgO and CaO were in MS1, MS3 and MS2. The quantification ion released was performed at 1, 6, 12 and 24 hours. It was observed that MS3 had performed the best condition in the releasing process of K+, Mg+, SO4 2- and Cl-. Although MS1 had higher nutrient content, MS3 released higher contents of those minerals among the samples. According to the result of this study, it was confirmed that MS3 has a high potential for hydroponic farming. [ABSTRACT FROM AUTHOR]

High-gravity technology was applied to the dissolution process between molten slag and solid modifiers to accelerate the modification of hot slag. In this study, MgO and SiO 2 rods were chosen as typical modifiers, and the effects of high-gravity (G = 800) and normal-gravity (G = 1) fields on the dissolution process between molten slag and solid modifiers were researched. The effects of high-gravity forces on the penetration depth and boundary layer of the dissolution process of the rod in molten slag were investigated using optical micrographs, X-ray fluorescence, X-ray diffraction, scanning electron microscopy, and electron probe microanalysis. Under high gravity conditions, the penetration depth of the slag melt into the solid rod was larger because the melt could enter deeper and smaller cracks and gaps, which increased the contact area and accelerated the dissolution process. The penetration depth increased from 0.1 mm to 1.07 mm in the MgO rod system and from 0.55 mm to 1.99 mm in the SiO 2 rod system. Moreover, the boundary layer of ions between the solid rod and slag melt became thinner, which promoted the diffusion of ions; the boundary layer thicknesses were reduced from 1.91 μm to 0.45 μm in the MgO rod system and from 96.88 μm to 51.63 μm in the SiO 2 rod system. In addition, high centrifugal forces could remove pores by pushing air bubbles from inner liquid–solid interfaces to the surface of the molten slag. The elimination of bubbles at the interfaces favored the penetration and dissolution processes. This study provides a rapid and effective new modification method to reduce the energy loss of molten slag and increase the output of modified slag. [ABSTRACT FROM AUTHOR]

The wetting and corrosion behavior of the corundum substrate anode by CaO–SiO 2 –MgO molten slag was investigated via the joint application of the sessile drop method with applied voltage and SEM-EDS technique. The slag drop exhibited a good wettability on the corundum substrate. The apparent contact angle at zero voltage slightly exceeded that at a 1 V applied voltage but was lower than those at 1.5 V and 2 V ones. Low applied voltage of 1 V had little effect on the corundum substrate's direct dissolution corrosion processes; high ones of not less than 1.5 V caused the electrode reaction to occur. The stirring effect of O 2 bubbles from the anode reaction aggravated the substrate's direct dissolution and physical stripping. It was found that the applied voltage could inhibit the slag penetration, and the apparent contact angle had no obvious relation with the direct dissolution thickness and penetration depth. A thin but almost continuous MgO⋅Al 2 O 3 (MA) layer could form at the slag/substrate interface at the applied voltage of 1.5 V. These results indicate the positive effect of applied voltage on the distribution of interfacial products and the molten slag penetration in reducing the corrosion of corundum anode under certain conditions. However, when the applied voltage was too high, the vigorous electrode reaction could aggravate the direct dissolution and physical stripping of the corundum anode, and damage the continuation of the formed interface product layer with a high melting point. [ABSTRACT FROM AUTHOR]

Chemical and physical analysis was performed to identify the molten slag composition and its ability to be used as alternative catalyst in pyrolysis of waste cooking oil. The implementation such type of catalytic material could be useful in reducing the process cost. To increase the efficiency (increase the active site) of molten slag, it was modified by acid washing that resulted in an increase in the acidity from 159 to 1224 µmol/g. The results showed that the yield of bio-fuel was increased and the product selective to n-C15 upon the modification of molten slag by acid treatment. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Turning molten slag into a solid state involves a complex cooling history that significantly influences the quality of the final product. It is crucial to unveil the crystallization dynamics of molten slag during practical cooling, particularly in the post-cooling course with temperature rise. In this work, we employed the single hot thermocouple technique to visually investigate the crystallization behavior of blast furnace slag. A series of control experiments were conducted to quantify the effects of temperature rise features and chemical composition on incubation time (τ o - τ l), crystallization temperature region (T o ∼ T e), and the average crystal growth rate (Vα). The results proved that the governing factor of V α changed from nucleation growth rate to nucleation rate, resulting in a significant difference in crystallization phenomena between the continuous cooling condition and temperature rebounding condition. Considering the post-peak temperature, temperature rise rate, and corrected optical basicity exerted remarkable effects on the crystallization behaviors, we established correlations for predicting τ o - τ l , T o , T e , and V α by fitting experimental data. These correlations offer valuable insights for optimizing cooling parameters in dry slag treatment, contributing to a comprehensive understanding of crystallization dynamics in high-temperature slag subjected to intricate cooling histories. [ABSTRACT FROM AUTHOR]

This research aims to investigate the influence of the slag basicity from 1.40 to 1.83 on dephosphorization of the hot metal with a CaO–FeO–SiO2–MgO–Al2O3 molten slag at the low temperature of 1653 K. The results indicated that the dephosphorization ratio was increased with the increase of basicity. Even at the low basicities of 1.73 and 1.83, the dephosphorization ratios can be as high as 77.3 and 80.7%, respectively. With the increase of basicity, the contents of P2O5 and total iron in the slag were increased, whereas the content of MnO was decreased. The distribution ratio of phosphorus (L P) was expressed as log ⁡ L P = 19.4 Λ − 6381 T + 5.244 + log ⁡ f P + 5 4 log ⁡ P ( O 2) . The L P values calculated by the present method are well consistent with the measurement values. Besides, the dark grey phase B and the light grey phase D could be considered as the phosphorus-rich phases containing C2S solid particles. [ABSTRACT FROM AUTHOR]

A simplified mathematical model of the processes of movement and heating of molten metal drops in liquid slag at ESR is proposed in two variants of problem definition: the drop preserves its initial spherical shape; the drop is deformed and takes the shape of a spheroid flattened in the direction of movement. It is shown that drop deformation makes an essential impact on the velocity and duration of its movement in the layer of slag, as well as on the drop surface area (at preservation of its volume), which determines the conditions of heating and interaction of drop metal with molten slag. It was proved that due to increase of surface area and lowering of movement velocity of larger diameter drops, their heating in the slag layer occurs more effectively, compared to spherical drops. Ref. 16, Tabl. 2, Fig. 11. [ABSTRACT FROM AUTHOR]

Water quenched blast furnace slag is an excellent hydrated material. However, dry granulation is a new treatment method for molten blast furnace slag that has numerous advantages compared to water quenching. This study investigated the size distribution of slag particles obtained from the dry granulation of molten slag. In addition, the effect of using the slag obtained from dry granulation in slag cement blends was analyzed. All the results showed that there was a wide size distribution range of blast furnace slag particles in ligament formation. The mean diameter of the solid particles decreased as the rotating speed increased. Meanwhile, the glass content in slag particles decreased for a fixed diameter of the metal collecting tray. The strength of slag cement concrete was low at a low rotating speed. In contrast, obtaining slag particles at a high rotating speed was beneficial for producing a compact structure in the slag cement blend. Unlabelled Image • The mean diameter of solid particles decreased with an increase in rotating speed. • It is easy to form compact structure in slag cement at high rotating speed. • The strength of slag cement was determined by slag powder size distribution. [ABSTRACT FROM AUTHOR]

The process of separation of slag and alloy and distribution of vanadium in casting slag during the casting process of multiperiod FeV50 preparation were analyzed using the principle of infinite fluid gravitational settling. The effects of slag viscosity, particle size, casting temperature, molten-slag thickness, and insulation system on total vanadium (TV) content in slag were investigated. The analysis demonstrates that vanadium mainly comprises vanadium oxide and incompletely deposited primary ferrovanadium alloy in the casting slag. The sedimentation rate of settlement alloy increases with an increase in the particle size and decreases with an increase in the slag viscosity. The dropping time of FeV50 alloy and floating time of molten slag is 24.9 and 1.2 min, respectively, when the casting conditions are as follows-casting temperature:1850℃, slag layer thickness:50 mm, particle size:100 μm, and slag composition mass fraction:65.2% Al2O3, 15.5% CaO, 14.6% MgO, 1.9% Fe2O3, and 0.9% SiO2. Through optimization experiments, the average vanadium mass content in the slag is reduced from 1.39% to 0.58% for the following casting conditions-slag layer thickness:35 mm, casting temperature:1900℃, slag component:60%-65% Al2O3, 15%-20% CaO, 9%-15% MgO; and casting insulation thickness:9 cm.

The structural properties of molten CaO–SiO2–P2O5–FeO slag system with varying slag basicity have been investigated by molecular dynamic (MD) simulations using the pairwise potential model. The result shows that more than 95 % Si and 98 % P are four coordinated and form tetrahedral structures. Non-bridging oxygen occupies a predominant position in the system. With basicity increasing from 0.6 to 1.5, the proportion of non-bridging oxygen increases from 66.3 % to 77.3 %, whilst the bridging oxygen decreases from 30.1 % to 10.2 %. Both the result of MD simulations and Raman spectroscopic analysis show the proportion of Q0 increases with increasing slag basicity, whilst Q2 and Q3 decrease. The degree of polymerization of CaO–SiO2–P2O5–FeO system decreases with increasing slag basicity.

Chemical and physical analysis was performed to identify the molten slag composition and its ability to be used as alternative catalyst in pyrolysis of waste cooking oil. The implementation such type of catalytic material could be useful in reducing the process cost. To increase the efficiency (increase the active site) of molten slag, it was modified by acid washing that resulted in an increase in the acidity from 159 to 1224 μmol/g. The results showed that the yield of bio-fuel was increased and the product selective to n-C15 upon the modification of molten slag by acid treatment. [ABSTRACT FROM AUTHOR]

Due to the large radiation and difficulties in determining the solid fraction, conventional methods are not appropriate to measure the thermal conductivity of high-temperature molten slag. This paper presents a method to measure the thermal conductivity of molten slag above 600 °C. Solidification of molten slag was implemented by using copper finger dip test. A mathematical model was established to describe the heat transfer process during solidification. Results indicate that when the temperature is between 600 and 800 °C, the thermal conductivity decreases with the increase in temperatures. In the initial stage of solidification, molten slag will transform from liquid to glass under rapid cooling process. As solidification proceeds, the cooling rate decreases gradually with time, and crystals begin to precipitate from liquid. For molten slag with short incubation time, the high nucleation rate of crystals will lead to large amount of crystals in the solidified layer and the higher thermal conductivity. [ABSTRACT FROM AUTHOR]

The distributions of Sb and Sn between slag and matte in equilibrium with tridymite in the Cu-Fe-O-S-Si system at 1200 °C (1473 K) have been measured. The experimental technique involves high-temperature equilibration in sealed quartz ampoule, rapid quenching, and direct measurement of phase compositions using Electron Probe X-ray Microanalysis (EPMA). The closed system equilibration approach was used to minimize the evaporation of Sb and Sn from the samples. The experimentally-determined distribution coefficients of Sb and Sn between slag and matte were found to increase with increasing Cu concentration in matte above 40 wt%. The new data have been used to refine the computational thermodynamics model for the system containing Sb and Sn at dilute concentrations. The molten slag phase is described using the Modified Quasichemical Model in the Quadruplet Approximation. Liquid matte and metal phases were modelled using single solution built within the Modified Quasichemical Model in the Pair Approximation. The thermodynamic model can be used to assess and predict the deportments of Sb and Sn between the slag and matte phases in the high-temperature pyrometallurgical production, refining and recycling of copper. [ABSTRACT FROM AUTHOR]

Abstract At present, centrifugal granulation has become the most promising method for waste heat recovery of molten slag. This paper investigates the effects of rotary disk configurations on particles characteristics with molten aluminum as the working medium. Four types of rotary disks and two kinds of particles characteristics which included particles size distribution and particles mean size were studied. It can be seen that the main particles sizes are populated in the range of 2.0~4.0mm for all disk configurations. Due to the special surface structure, the particles produced by curved-block disk and arc-edge disk configurations are more concentrated compared to other two types of disks. Besides, the results shown that the mean size of particles generated by curved-block disk is smaller. All the conclusions will be helpful for future development of the high-temperature molten slag dry granulation systems. [ABSTRACT FROM AUTHOR]

In order to improve the recovery of iron resource in molten basic oxygen furnace (BOF) slag through carbothermal reduction, bottom blowing argon gas is used to promote the mixing efficiency between molten slag and graphite particles in the converter. In the present work, computational fluid dynamic-discrete particle model (CFD-DPM) method coupled with the reduction kinetic model of FeO in molten slag by graphite particle is employed to simulate the multiphase system composed of molten slag, graphite particle and argon gas. The motion and dispersion characteristics of graphite particles in a bottom-blown converter were mainly investigated, and the decrease of graphite particle diameter caused by the reduction reaction was considered. A particle dispersion index was also proposed to evaluate the distribution uniformity of graphite particles in the molten slag. In addition, the effects of initial particle diameter and bottom tuyere arrangement on the dispersion characteristics of graphite particles were further discussed. The results show that the proportion of large-sized particles is higher in the inactive-flow zone and the motion trajectory of graphite particles can be divided into two regimes. Graphite particles with an initial diameter of 5 mm and the converter with six bottom-blown tuyeres are more conducive to the homo-dispersion of graphite particles. The dispersion characteristics of graphite particles in a bottom-blown converter were investigated for molten BOF slag reduction. Based on the migration distance and particle size decrease, the motion trajectory of graphite particles can be divided into two regimes. Graphite particles with an initial diameter of 5 mm and the converter with six bottom tuyeres are more conducive to the particle homo-dispersion and reduction of molten BOF slag. [Display omitted] • Reduction reaction-induced decrease in graphite particle diameter is studied. • The motion trajectory of graphite particles can be divided into two regimes. • A dispersion index is proposed to assess graphite particle distribution uniformity. • 5 mm particle diameter and 6 tuyeres are conducive to the particle homo-dispersion. [ABSTRACT FROM AUTHOR]

Preparing high added-value materials from molten slag directly by modifying molten slag has drawn a great interest in the utilization of molten slag because of its high efficiency during the integrated utilization of the heat and slag. In this paper,molten steel slag and sands were selected as typical molten slag and modifiers,respectively. The effects of the amount of added modifiers on the waste liquid sensible heat of modified molten slag were studied during the modification process,which was subsequently confirmed by industrial test. It is indicated that the sensible heat of modified molten slag increases at first and then decreases with the addition of modifiers. The sensible heat improves with the increase in mass fraction of modifiers from 5% to 11% and reaches the maximum at the mass fraction of 11%. The optimal amount of modifiers ranges from 11% to 19% in consideration of both the utilization of sensible heat and the performance of modified molten slag. Furthermore,the industrial test verifies that both the fluidity of modified molten slag and the stability of cooled modified slag are significantly improved at the addition of about 12% modifiers.

A granulated slag, which goes to a dump, forms in the metallurgical enterprise near Novoshakhtinsk (Primorye Territory, Far East) upon processing of the germanium-containing raw materials of the Pavlovsk brown coal deposit. The reclamation of this technical waste needs an energy efficient ecologically safe method that meets the requirements of ecological norms. According to modern requirements, the problem of reclamation of the slag of cyclone smelting should be solved before the beginning of operation of the enterprise. The project documentation recommends using the slag of cyclone smelting in building or the production of building materials. The chemical and granulometric compositions of the slag and the properties of the material during interaction with water should be determined to find the direction of reclamation of the slag of cyclone smelting. Using reduction-sulfidizing cyclone smelting with flux and sulfidizer additives, we formed a granulated slag, the properties of which are close to those of the commercial slag of cyclone smelting, under laboratory conditions. Samples are prepared for a further investigation. Using modern experimental techniques, we determined the composition and properties of the slag and performed chemical analysis to find macrocomponent contents and X-ray diffraction analysis for an ecological estimation. The physicochemical and organoleptic characteristics of the slag are determined according to the existing standards. For example, the maximum particle size in the slag is 10 mm and the content of the particles the size of which is more than 5 mm is 9.7%, which corresponds to GOST 5578–94. The density and humidity of the slag are determined. The solution that forms during interaction with water has a weak alkaline reaction, which does not prevent the use of the material in an industrial process. The slag is shown to be suitable for further reclamation. [ABSTRACT FROM AUTHOR]