Viscosity Of Blast Furnace Slag Research Articles

Щодо взаємодії і захоплення металевих крапель доменним шлаком

The mechanism of capture of metal drops by the slag melt was investigated using blast furnace slag as an example. The role of the viscosity of the blast furnace slag in reducing iron loss at the output from the blast furnace is shown. Reducing the viscosity of slags contributes to the rapid settling of small drops of cast iron in the slag volume. It is noted that the CaO/SiO2 ratio is an important parameter that changes the viscosity of blast furnace slag. To ensure the minimum viscosity of blast furnace slag, it is necessary to establish the optimal chemical composition of the slag, in particular the CaO/SiO2 ratio. A study of the temperature dependence of the viscosity of blast furnace slag melts was carried out using the method of estimating the content of the solid phase in the melt during its cooling. Calculations of the volume fraction of the solid phase for blast furnace slags were performed. An increase in the CaO/SiO2 ratio in slags leads to an increase in their crystallization ability. The microstructure and chemical composition of individual phases of a blast furnace slag sample were studied using scanning electron microscopy (SEM). It was established that the experimental slag contained at least three phases. The main (matrix) phase was an amorphous phase, which contained mainly SiO2 and Al2O3. The volume of the matrix phase contained interspersions of the crystalline phase of different sizes, which mainly included CaO and SiO2. In the volume of the crystalline phase, a metallic phase was found, which consisted mainly of Fe and Mn and had a regular rounded shape. The mechanism of capture of a metal droplet by slag is described. The metal drop serves as a frame (center) for the nucleation of the crystalline phase in the slag volume, as its surface energy decreases at the "metal drop - slag" interface. An increase in the mass of the crystalline phase around the metal drop leads to an increase in its lifting force and capture of the metal drop. Keywords: blast furnace slag, viscosity, metal loss, crystallization, scanning electron microscopy.

Viscosity Estimation of TiO2-Bearing Blast Furnace Slag with High Al2O3 at 1500 °C

Slag compositions are significant for the viscosity of blast furnace slag. An improved Urbain model (IUM) was proposed by introducing R5 ((X(CaO) + X(MgO) + 2X(TiO2))/(2X(SiO2) + 3X(Al2O3))) and N (X(MgO)/3X(Al2O3)) as the model parameters. By comparing IUM with other models, the model parameters of R5 and N are more reasonable and suitable for TiO2-bearing blast furnace slag, and IUM for predicting viscosity has a higher precision, and its relative error is only 10%. The viscosity isolines of the CaO–SiO2–15%Al2O3–MgO–2.5% TiO2 system were plotted, and the results show that the viscosity center of the slag is between Rw2 (w(CaO)/w(SiO2)) = 0.77–1.39 and Nw (w(MgO)/w(Al2O3)) = 0–1.37, the value of the viscosity center is 0.3 Pa·s, the viscosity increases gradually from the center to the outside, and the viscosity of the slag gradually decreases with the increase in Nw and Rw2. Furthermore, FTIR (Fourier Transform Infrared Spectroscopy) analysis was carried out in order to understand the mechanism between the slag structure and viscosity. With the increase in Nw and Rw2, the peak values of the symmetrical stretching vibration of non-bridging oxygen in the Si–O tetrahedral structure of slag decrease, and the slag structures depolymerize, which leads to the decrease in the viscosity of the slag.

Influence of unburned pulverized coal on the viscosity of blast furnace slag

ABSTRACT In order to explore the influence of unburned pulverized coal in ironmaking on the viscosity of blast furnace slag, the impact of temperature, volume fraction of solid particles and the rotating speed on the viscosity of CaO–MgO–Al2O3–SiO2 heterogeneous slag were studied by experiment. The calculation model of relative viscosity of heterogeneous slag containing unburned pulverized coal is corrected. The results showed that the viscosity of heterogeneous slag increased with the increase of the volume fraction of the solid particles, and decreased with the increase of the rotating speed. For the heterogeneous slag with the same composition, the relative viscosity is not affected by the temperature and decreases with the increase in the rotating speed. The impact of unburned pulverized coal solid particles on the viscosity of the slag was much larger than the predicted value of the Einstein–Roscoe equation.

Granulation mechanism of gas quenching blast furnace slag with different basicities

ABSTRACT In order to overcome the environmental pollution caused by traditional water-quenching slag treatment and recover a large number of waste heat from blast furnace slag (BFS), the dry granulation process had attracted more and more attention, in which the granulation process was the key. The slag granulation and the crystallization mechanism of the BFS were studied, and the hot experimental results were analysed. The results showed that the viscosity of BFS decreased with increasing basicity, thus was beneficial to the broken of BFS. The higher the basicity, the smaller the crystallization activation energy of BFS, and the bigger the crystal growth index, which was more beneficial to the crystal nucleation and growth of BFS. Reducing the basicity or increasing the cooling rate could be more beneficial to the preparation of amorphous slag beads. The basic slag could obtain the same amorphous results as acidic slag by increasing the gas quenching speed.

Research on characteristics and modelling estimation of molten BF slag viscosity in the process of slag waste heat recovery

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 (BF) slag as heat carrier to recover the waste heat. The results showed that the viscosity and melting temperature of BF 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 BF 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 BF 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%.

Effect of Al2O3, MgO, and CaO/SiO2on Viscosity of High Alumina Blast Furnace Slag

The effects of Al2O3, MgO, and binary basicity on the viscosity of high alumina blast furnace slag are studied systematically at the temperatures of 1773 K and below using the orthogonal experimental design method. The results show that, at fixed binary basicity (CaO/SiO2) between 1.1 and 1.2, higher Al2O3 content increase the slag viscosity due to the polymerization of the aluminate structures. At fixed Al2O3 content between 15 and 20%, increasing the CaO/SiO2 from 1.1 to 1.2 lead to lower viscosity due to the depolymerization of the aluminate structures. At fixed MgO between 9 and 11%, both increasing Al2O3 content and CaO/SiO2 can make the melting temperature increase. In addition, the viscosity data of high alumina blast furnace slag was in accordance with the estimated values of viscosity by Riboud model. Understanding the mechanism of Al2O3, MgO, and binary basicity on the viscosity of blast furnace slag can provide a promising method for optimizing its viscosity value and improving the blast furnace operation.

Study of the effect of the MgO/Al2O3ratio on viscosity of blast furnace slag

The effect of the MgO/Al2O3 ratio on the viscosity of blast furnace slag was studied systematically at temperatures of 1773 K and below under the conditions of the same Al2O3 content and binary basicity. The results showed that the viscosity and the melting temperature of the slag first decreased, then increased, while the MgO/Al2O3 ratio decreased from 0.90 to 0.75. The appropriate MgO/Al2O3 ratio, which is not too high or too low, could optimize the properties of blast furnace slag significantly, such as stability and fluidity. In addition, according to the effect of depolymerization of MgO and the strengthening of Al2O3, the influence of the structure on the viscosity coincides with the results of these experiments under the combined action of MgO and Al2O3. Understanding the effect of the mechanism of MgO/Al2O3 on the viscosity of blast furnace slag could provide a promising method for optimizing its viscosity value and improving the blast furnace operation.

Modelling effects of additives on viscosity of molten blast furnace slag

A simple model was established to calculate and predict the effects of network modifiers on the viscosity of molten blast furnace slag by relating the effects to the ionic bond force parameter. It was found that the model performs very well in calculating the viscosity of blast furnace slags containing FeO, MnO, BaO, Na2O, K2O and CaF2, with relative error Δ of 0·219 (±0·196) and overall absolute error (root mean square error) of 0·402 Pa s. The viscosity decreasing abilities are in the order of K2O<(Na2O, BaO)<(CaO, MnO, FeO)<MgO<CaF2. The effects of other network modifiers on the viscosity can also be predicted. As alkali metal oxides have much lower bond strength and smaller molar weight, their viscosity decreasing abilities evolve differently from divalent metal network modifiers, whereas the viscosity decreasing abilities of alkali and divalent metal network modifiers increase linearly with increasing I/M, where I is ionic bond strength parameter, and M is molar weight.

A General Viscosity Model for Molten Blast Furnace Slag

Blast furnace slag is the most abundant slag in the steel industry. Its metallurgical properties are determined to a great extent by its viscosity. Therefore, it is necessary to establish a reliable viscosity model for blast furnace slag. In the current work, a simple, accurate, and physically meaningful viscosity model for a wide composition range of blast furnace slags is developed based on the Vogel–Fulcher–Tammann (VFT) equation: log η = A + B/(T − C). The model is calibrated by a database containing 365 compositions and 1233 measurements of synthetic and industrial slags. The parameter A has a value of −3.10. The parameters B and C are related to the mass fraction ratio of (CaO + MgO) to (SiO2 + Al2O3) and liquidus temperature of the slag, respectively. Present viscosity model accurately predicts the viscosity of blast furnace slag with relative average error (Δ) of 0.211 (±0.180) and root mean square error (RMSE) of 0.239 Pa·s. A slight modification of this model can also predict the glass transition temperature of blast furnace slag satisfactorily.

Structural aspects of blast furnace slag

Interdependence of structure and viscosity of blast furnace slag is discussed based on the available literature. Emphasis is given to both, bridging tendency and network breaking/modifying tendency of the constituents. It is clearly pointed out that slag viscosity cannot be explained only by depolymerization through an increase in basicity, despite the fact that an increase in basicity of the slag, in general, lowers the viscosity of the slag by a process of generation of discrete anions containing simple chains and/or rings by causing depolymerization of the 3D silicate network.

Study on Viscosity of Titania Bearing Blast Furnace Slag

The viscosity of blast furnace slag which was taken from Shuicheng Iron and Steel Group Co. Limited was experimentally measured by column whirling method using the ND-II slag viscosity tester. By adding analytical reagent CaO, SiO2, Al2O3, MgO and TiO2 in accordance with orthogonal design, the contents of compositions in slag were adjusted in CaO/SiO2=1.16-1.24, 14.06-17.06mass%Al2O3, 5-7mass%TiO2, 8.96-9.96mass%MgO. The results showed that the viscosity of BF slag decreased with increasing TiO2; when the Al2O3 content in the slag was 14.06%, the viscosity of BF slag had a lowest value, a highest value had for 15.56% Al2O3 content, and a lower value for 17.06% Al2O3 content. There is no significant effect on the viscosity by both the magnesia and the binary basicity.

硬質水砕スラグ製造温度域における高炉スラグと合成スラグの粘度,表面張力,密度

Viscosity, surface tension, and density of blast furnace slag and synthetic slags which had nearly the same composition as that of the blast furnace slag were measured below the smelting temperature. The following results were obtained:(1) Viscosity of synthetic CaO-SiO2-Al2O3-MgO slags increases with increasing SiO2 and Al2O3 contents, and decreases with increasing CaO and MgO contents. Small amounts of another compounds contained in the blast furnace slag cause the decrease of vicosity, and the extent of effect of these compounds on viscosity is similar to that of MgO.(2) Surface tension of quaternary CaO-SiO2-Al2O3-MgO system is not influenced by the interchange of Al2O3 and MgO but increases markedly with increasing (CaO/SiO2) mol. The surface tension of the blast furnace slag is 472 to 498 dyn/cm in the temperature range 1 380° to 1 500°C, and sulfur has a great influence on the decrease of surface tension. The surface tension of all the systems studied here decreases with increasing temperature.(3) Great increase of viscosity of blast furnace slag occurs when cooled below 1 405°C to 1 375°C, and it is made clear that this temperature range corresponds to the upper limit of the operation temperature to produce hard granulated slag in the factory.

溶融鑛滓の粘性(II)

To clarify the effect of MgO on the viscosity of blast furnace slag, viscosities of synthetic CaO-SiO2-Al2O3-MgO slags were measured by the rotating inner-cylinder viscosimeter as in the case of the first report. (Tetsu-to-Hagane, Vol. 38, 1952, 12) Iso-viscosity lines at 1, 500 and 1, 600°C are drawn on the diagram (Fig. 1, 2, 3)When MgO was added to GaO-SiO2 slag, the viscosity decreased with increasing amounts of MgO up to about 20%, but thereafter increased. The region of low viscosity in Cao-SiO2-MgO slag was greater than that in the CaO-SiO2-Al2O3 slag.When MgO was added to CaO-SiO2-Al2O3 slag, the viscosity decreased and moreover changein viscosity at constant temperature caused by the change of slag composition became small, but these beneficial effects of MgO were less noticeable than those reported by the previous investigator. With respect to the fluxing quality, MgO had nearly as much influence in reducing slag viscosity as CaO or slightly less.

Societies and Academies

LONDON. Faraday Society, December 12, 1917.—Mr. W. R. Bousfield, vice-president, in the chair.—Prof. A. W. Porter: The thermal properties of sulphuric acid and oleum. The object of this paper is to supply data at various temperatures for the heats of solution and dilution and evaporation, both of sulphuric acid and oleum. Pre-existing data apply only to atmospheric temperatures; but technical processes take place at various temperatures up to 200° C. or above. These additional data are obtained by indirect methods either from vapour pressures (of H2O or SO3) by means of Clapeyron's formula or from thermal capacities.—W. R. Bousfield: Isopiestic solutions. Solutions of KC1, LiCl, NaCl, and KNO3 of equal vapour pressure are placed together in an exhausted vessel, so that interchange of aqueous vapour may take place. Hence is indicated an accurate method of determining the vapour pressure of an aqueous solution, by comparison with the equal vapour pressure of a solution of LiCl. The observations lead to the conclusion that for a pure salt without water of crystallisation there is, at a given temperature, a certain vapour pressure of water below which the dry salt surrounded bv aqueous vapour will not take up water, and will, if it is not dry, become dried. This pressure may be called the critical hydratidn pressure of the salt at the given temperature.—Dr. J, W. McBain: Notes on the system of recording rate of chemical reaction. The usual equation representing rate of reaction may be written in the form fci = (remainder of expression). The author proposes so to choose the unit of time that fe is always unity. A single number will then completely record the rate of reaction.—A. L. Feild: The viscosity of blastfurnace slag and its relation to iron metallurgy (seep. 373). O.G. Le Bas: The refractivities of saturated and un-saturated compounds. The refractivities of unsaturated compounds, together with unsaturated systems containing conjugated unsaturated groups, have been considered. Benzene has been shown to be possessed of no anomaly. Cross-linking has been assumed in some cases. The effects of conjugation of ethenoid and carbonyl groups have been shown, whilst nitrates, nitrites, and nitro-compounds have been studied. The oximino-group especially has been taken into consideration. The cycle-paraffins, substituted and un-substituted, have been considered, together with a number of terpenes and derivatives. Anomalies have been connected with the side-chains or substituents and the appropriate numbers ascertained. The larger anomalies are connected with the trimethylene ring. Those for benzene derivatives have been ascertained. The unsubstituted hydrocarbons show no anomalies.—Dr. E. B. Ludlam: The effect of hydrogen chloride on the nitrogen-hydrogen equilibrium. The paper records an experimental attempt tft simplify the difficult conditions of high temperature at high pressure under which the Haber synthesis takes place. It was thought that the presence of hydrochloric acid during the synthesis would displace the equilibrium in the direction of the formation of ammonia. The result of the experiments was negative.—Dr. H. B. Maxted: The influence of carbon monoxide on the velocity of catalytic hydro-genation. The inhibitive effect of small percentages of carbon monoxide on the velocity of hydrogenation of olive oil in presence of nickel has been studied quantitatively.

The viscosity of blast-furnace slag and its relation to iron metallurgy, including a description of a new method of measuring slag viscosity at high temperatures

The viscosity of blast-furnace slag and its relation to iron metallurgy, including a description of a new method of measuring slag viscosity at high temperatures