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The vaporization of vanadium pentoxide from CaO-SiO2-VOx ternary slags using different gas treatment regimens and parallel vacuum gas extirpation to treat V-bearing slags at 1873 K has been developed in the present study. The novelty of the present study is to monitor the effect of parallel alumina dissolution on the vaporization phenomenon. Vanadium pentoxide has high vapor pressure at the temperatures over 1500 K. When CaO-SiO2-VOx ternary slags, kept in dense alumina crucibles, are injected with oxygen, V2O5 gas bubbles are formed which are forced out by using vacuum extirpation. The vanadium pentoxide could be then collected in the exhaust gases. The mechanism of the process phenomenon is described as the formation of V2O5 gas phase resulting from the oxidation of the lower-valent oxides present in the slag. This gas phase would form microbubbles in the molten slag bulk phase due to low surface tension between the gas phase and the slag, thereby increasing the contact surface. At the same time, the crucible material would dissolve in the slag causing an increase in the slag viscosity. Due to the high slag viscosity of the bulk slag, these microbubbles formed would have difficulty in coalescing and reaching the slag surface. The escaping of the bubbles into the gas phase is enabled by the vacuum extirpation., QC 20220214

This paper presents the results of two experimental studies on diffusion of SiO2 in “silicomanganese” (SiO2-MnO-CaO-Al2O3- MgO) slag and CaO in calcium aluminosilicate slag. The diffusivity of SiO2 was measured in the temperature range of 1400-1550 °C; while the diffusivity of CaO was determined at 1430-1600°C. The effects of additives on the chemical diffusivities of SiO2 and CaO were also examined. Addition of CaO and MnO to the silicomanganese slag increased silica diffusivity, while addition of SiO2 and Al2O3 slowed it down. Addition of TiO2 and MnOx to the aluminosilicate slag increased the diffusivity of CaO, while the addition of SiO2 had a negative effect on the diffusivity of CaO. Analysis of diffusivity in relation to the structure of silicate melts demonstrated a good correlation between diffusion coefficients of SiO2 and CaO and NBO/T (non-bridging oxygen per tetrahedrally coordinated atom).

In order to apply the hot wire method for metallurgical slags at steelmaking temperatures, a numerical model was developed, cold model experiments were conducted and test measurements using a high temperature experimental setup were carried out. To minimize natural convection and obtain more reliable measurements, the crucible diameter, the hot-wire diameter, the applied current, the position of the wire in the crucible, and the cooling on the upper surface of the crucible were studied. Investigations into the choice of sheathing material of the circuit exposed to the slag were also made. It was found that only certain materials were suitable for slag measurements depending on slag composition and temperature. The electrical resistivity of the hot wire was measured to make the thermal conductivity calculation more reliable. The wire diameter also played a major role, because of the heat generation per surface area. The thermal conductivity should be derived from the values measured during the first seconds. In this initial stage, the effect of the natural convection as a function of the wire position in the crucible, the cooling on the top surface, and the diameter of the crucible are negligible. A compromise has to be made in choosing the electrical current, since higher current results in higher sensitivity but at the same time in more natural convection., QC 20130830. Updated from accepted to published.

In the present work, a modified thermal analysis technique was used for studying the heat effect of slag foaming with carbonates addition. Experiments were conducted by sinking limestone and dolomite pieces of defined shapes (together with iron sinkers) in molten slag and monitoring the temperature changes accompanying the decomposition of carbonates. The heat effects of dolomite and limestone decompositions were determined at 1623 K (1350 A degrees C) and 1673 K (1400 A degrees C). It was found that the decomposition energy for dolomite and limestone for the studied slag composition is in the range of 56 to 79 pct of theoretical values, which is linked to the energy-saving effect of slag foaming. No influence of sample shape on decomposition energy was found for both limestone and dolomite., QC 20100913 Uppdaterad från submitted till published (20110318).

In the present work, the interfacial reactions between molten synthetic slag (Al2O3-CaO-SiO2- FeO) and liquid iron alloy were investigated at 1873 K with the aid of an X-ray radiographic apparatus. The mother slag consists of 40 mass%CaO, 40 mass%SiO2 and 20 mass%Al2O3.FeO was added to this slag at the experimental temperature, and the movement of the droplet and deformation of the droplet shape were monitored in the dynamic mode. The change of the shape of the droplet is discussed based on the reaction and mass transfer at the slag/metal interface. From the movement of the droplet, interfacial velocity of the metal droplet induced by Marangoni flow was estimated and compared with the results obtained in the present laboratory earlier. The importance of surface velocity values on steel refining process simulations is discussed., QC 20140922

In the present work, the interfacial reactions between molten synthetic slag (Al2O3–CaO–SiO2–FeO) and liquid iron alloy were investigated at 1873 K with the aid of an X‐ray radiographic apparatus. The mother slag consists of 40 mass%CaO, 40 mass%SiO2 and 20 mass%Al2O3. FeO was added to this slag at the experimental temperature, and the movement of the droplet and deformation of the droplet shape were monitored in the dynamic mode. The change of the shape of the droplet is discussed based on the reaction and mass transfer at the slag/metal interface. From the movement of the droplet, interfacial velocity of the metal droplet induced by Marangoni flow was estimated and compared with the results obtained in the present laboratory earlier. The importance of surface velocity values on steel refining process simulations is discussed.

In the present paper, the electrical conductivities of molten silicates systems, CaO-MgO-SiO2, Na2O-MgO-SiO2, CaO-FeO-SiO2 and CaO-MgO-MnO-SiO2 (SiO2 = 45wt %) were estimated by the mass triangle method developed earlier by Chou. The computed results are compared with other approaches found in the literature. The predictions show satisfactory agreement with experimental results reported in the literature. A correlation was also made between the cation-oxygen ion attraction parameter I and the electrical conductivities of slags. It was found that the electrical conductivity varies linearly with I when the content of transition metallic ions is less than 0.2 mole fraction. Beyond this, the effect of electronic conduction is expected to dominate. On the basis of the present approach, the electrical conductivities of higher order systems can be estimated. The approach suggested in the present paper offers a powerful tool to design slags for applications in metallurgical processes., QC 20100813

In the present work, a method to measure stress relaxation of molten slags, developed earlier by one of the authors, was applied to mould flux slags as well as synthetic slags. The molten slag was sandwiched by two Pt plates and was compressed. And stress relaxation tests (the structural relaxation of molten slags) have been conducted by compressing the molten slags as well as mould flux slags at strain rates of 10 mm/min. The results of stress relaxation tests were discussed from the viewpoint of relaxation time and structure of slags with the aid of Raman spectroscopy. The stress relaxation behavior is found to be linked to the structure of slags. The residual stress after a compression was increased with increasing of Al2O3 content and with decreasing of CaF2 content. The relaxation behavior was changed drastically with increasing of temperature for some molten slags., QC 20100525

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QC 20101203

Within the metallurgical industry as well as the underground mine industry, there is a need for on-line level detection in the different production processes and their material feeding systems. Microwave technology is a versatile, non-invasive measurement technique, which has a number of advantages compared with penetrating probes, laser and radar technology, and echo sound technique. In its extension, it could also be used for qualitative and quantitative analysis of waste gases due to the presence of specific molecules. This contribution describes the introduction of microwave technology in different metallurgical as well as underground mine production processes with the emphasis on EAF's.

The effects of super-gravity field on metal-slag separation at different gravity coefficients were investigated in this study. In a super-gravity field, the liquid metal concentrated along the direction of super-gravity, while the molten slag migrated and aggregated along the opposite direction thereafter separated from the metal. Moreover, a straight interface between the metal and slag appeared in the perpendicular direction to the super-gravity. Consequently, increasing the gravity coefficient could definitely increase the driving force of phase separation between metal and slag, and so enhance the removal of oxide and the purity of metal significantly. (Authors.), The effects of super-gravity field on metal-slag separation at different gravity coefficients were investigated in this study. In a super-gravity field, the liquid metal concentrated along the direction of super-gravity, while the molten slag migrated and aggregated along the opposite direction thereafter separated from the metal. Moreover, a straight interface between the metal and slag appeared in the perpendicular direction to the super-gravity. Consequently, increasing the gravity coefficient could definitely increase the driving force of phase separation between metal and slag, and so enhance the removal of oxide and the purity of metal significantly. (Authors.)

The object of this study was to explore the effects of basicity (CaO/SiO2 ratio), MgO and Al2O3 on viscosity and melting temperature of molten slag in the process of coal gasification with blast furnace slag as heat carrier to recover the waste heat. The results showed that the viscosity and melting temperature of blast furnace slag decreased first and then increased with CaO/SiO2 ratio increasing, and the suitable CaO/SiO2 ratio was 1.10-1.20. Both viscosity and melting temperature increased with the increasing of MgO and Al2O3 in the slag, which should be lower than 8.22 and 11.00%, respectively. What is more, the viscosity estimation model for molten blast furnace slag was established according to the Urbain model and experimental data of slag viscosity. In the model, the activation energy was calculated using slag compositions based on the redefine of material types in the slag, and the temperature was described by the Weymann-Frenkel equation. The viscosity of blast furnace slag system estimated by proposed viscosity estimation model (modified Urbain model) fitted well with the experimental data and the mean deviation was about 17.98%. (Authors.)., The object of this study was to explore the effects of basicity (CaO/SiO2 ratio), MgO and Al2O3 on viscosity and melting temperature of molten slag in the process of coal gasification with blast furnace slag as heat carrier to recover the waste heat. The results showed that the viscosity and melting temperature of blast furnace slag decreased first and then increased with CaO/SiO2 ratio increasing, and the suitable CaO/SiO2 ratio was 1.10-1.20. Both viscosity and melting temperature increased with the increasing of MgO and Al2O3 in the slag, which should be lower than 8.22 and 11.00%, respectively. What is more, the viscosity estimation model for molten blast furnace slag was established according to the Urbain model and experimental data of slag viscosity. In the model, the activation energy was calculated using slag compositions based on the redefine of material types in the slag, and the temperature was described by the Weymann-Frenkel equation. The viscosity of blast furnace slag system estimated by proposed viscosity estimation model (modified Urbain model) fitted well with the experimental data and the mean deviation was about 17.98%. (Authors.).