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1.
A. A. Babenko S. A. Istomin V. I. Zhuchkov A. V. Sychev V. V. Ryabov A. G. Upolovnikova 《Russian Metallurgy (Metally)》2017,2017(5):372-375
The simplex lattice method of planning experiments is used to study the viscosities of CaO–SiO2–Al2O3–8% MgO–4% B2O3 slags in a wide chemical composition range. For each viscosity, we developed an adequate mathematical model in the form of a reduced third-order polynomial. The results of mathematical simulation are presented in composition–viscosity diagrams. Composition regions with a high fluidity of slags, the viscosities of which are 0.8–1.2 Pa s in the temperature range 1500–1600°C, are indicated in the diagrams. 相似文献
2.
The results of thermodynamic simulation of the desulfurization of a medium-carbon steel by slags of the CaO–SiO2–MgO–Al2O3–B2O3 system are presented. The HSC Chemistry 6.12 software package is used for the simulation. The thermodynamic simulation is performed for 20 various chemical compositions of slags with various B2O3 contents (1–4%)1 and basicities ((CaO)/(SiO2) = 2–5). The computations are performed using the Equilibrium Compositions module in the temperature range from 1500 to 1700°C with an increment of 50°C at a gas phase pressure of 0.1 MPa. The main results of the calculations are presented as the dependences of the change in the sulfur content in steel [S] on the temperature, the content of B2O3, and the slag basicity. An increase in the temperature of metal desulfurization from 1500 to 1700°C exerts a favorable effect on the sulfur content for the studied range of slag basicities. In particular, the sulfur content in steel decreases from 0.012 to 0.009% when steel is processed with the slag having 3% B2O3 and a basicity (CaO)/(SiO2) = 2. A positive effect of an increase in the slag basicity from 2 to 5 on metal desulfurization is observed: the degree of desulfurization increases from 61.1 to 97.2% at 1600°C and 3% B2O3 content in the slag. As the B2O3 content in a slag increases from 1 to 4%, its refining properties decrease significantly in the range of basicity not higher than 2. In the range of high slag basicities (3–4), the negative effect of acidic oxide B2O3 on the refining properties of the slag decreases, providing low sulfur contents (which do not exceed [S] = 0.003–0.004% at 4% B2O3). At a slag basicity of 5, the sulfur content in steel decreases to 0.001%, all other things being equal. The simulation results can be used for the calculation of steel desulfurization processed by slags containing B2O3. 相似文献
3.
Viscosities of some quaternary slags in the Al2O3‐CaO‐MgO‐SiO2 system were measured using the rotating cylinder method. Eight different slag compositions were selected. These slag compositions ranging in the high basicity region were directly related to the secondary steel making operations. The measurements were carried out in the temperature range of 1720 to 1910 K. Viscosities in this system and its sub‐systems were expressed as a function of temperature and composition based on the viscosity model developed earlier at KTH. The iso‐viscosity contours in the Al2O3‐CaO‐MgO‐SiO2 system relevant to ladle slags were calculated at 1823 K and 1873 K for 5 mass% MgO and 10 mass% MgO sections. The predicted results showed good agreement with experimental values and the literature data. 相似文献
4.
In thermodynamic modeling of the desulfurization of steel by CaO–SiO2–MgO–Al2O3–B2O3 slag on the basis of HSC 6.12 Chemistry software (Outokumpu), the influence of the temperature (1500–1700°C), the slag basicity (2–5), and the B2O3 content (1–4%)1 on the desulfurization is analyzed. It is found that the sulfur content is reduced with increase in the temperature from 1500 to 1700°C, within the given range of slag basicity. At 1600°C, the sulfur content in the metal is 0.0052% for slag of basicity 2; at 1650°C, by contrast, its content is 0.0048%. Increase in slag basicity from 2 to 5 improves the desulfurization, which increases from 80.7 to 98.7% at 1600°C. If the B2O3 content in the slag rises, desulfurization is impaired. At 1600°C, the sulfur content in the metal may be reduced to 0.0052 and 0.0098% when using slag of basicity 2 with 1 and 4% B2O3, respectively; in the same conditions but with slag of basicity 5, the corresponding values are 0.00036 and 0.00088%, respectively. Note that desulfurization is better for slag without B2O3. According to thermodynamic modeling, metal with 0.0039 and 0.00019% S is obtained at 1600°C when using slag of basicity 2 and 5, respectively, that contains no B2O3. The results obtained by thermodynamic modeling for the desulfurization of metal by CaO–SiO2–MgO–Al2O3–B2O3 slag of basicity 2–5 in the range 1500–1700°C are consistent with experimental data and may be used in improving the desulfurization of steel by slag that contains boron. 相似文献
5.
E. García‐Ramos A. Romero‐Serrano B. Zeifert P. Flores‐Sánchez M. Hallen‐López E.G. Palacios 《国际钢铁研究》2008,79(5):332-339
Chromium containing slags from stainless steelmaking may be leached by acidic environments, therefore they should be treated before being stockpiled or land filled. In this work, synthetic slags were prepared and the effect of CaO/SiO2, Cr2O3, MgO and Al2O3 contents on the stability of the mineralogical species formed was analysed. The morphology and composition of the slags were determined by XRD and SEM‐EDS, whilst their chemical stability was evaluated by leaching with an aqueous acetic acid solution. It was found that CaCr2O4 and CaCrO4 are present in slags prepared with neither MgO nor Al2O3. The Al2O3‐based slags mainly produced Ca2Al2SiO7 and the Cr(VI)‐containing oxide complex Ca4Al6CrO16, whilst MgO‐based slags produced Mg Cr2O4 as main mineralogical species. Additionally, Eh‐pH diagrams for the Ca‐Cr‐H2O and Mg‐Cr‐H2O systems at 25°C were constructed. The results showed that the lowest chromium concentration levels in the leaching liquors corresponded to MgO‐based slags owing to the stable binding of chromium in spinel with MgO. It was also observed in the Al2O3‐based slags that when increasing the slag basicity from 1 to 2, the leachability of the slags was notably increased. 相似文献
6.
A thermodynamic study was made on the MnO‐CaO‐MgO‐SiO2‐Al2O3 slags that are typical of the production of ferromanganese in submerged arc furnaces. The Al2O3 content of the slags was kept constant at 5 per cent by mass. The activity‐composition relationship in Pt‐Mn binary alloys were re‐determined for calibration purposes at 1300, 1400 and 1500°C and po2 values between 5.40×10?6 and 4.54×10?13 atm. A linear regression equation was derived to predict the activity coefficients of manganese, in Pt‐Mn alloys at 1500°C. The effect of concentration, basicity ratio and CaO‐to‐MgO ratio on MnO activities in above mentioned complex slags was investigated at 1500 °C and at two different po2 values of 4.76×10?7 and 5.80×10?8 atm. It was found that aMno values increase with increasing MnO, and tend to increase with an increasing CaO‐to‐MgO ratio. The aMnO values also increase with increasing basicity ratio. The activity coefficient of MnO increases with an increase in its mole fraction in the slag. Quadratic multivariable regression model equations which represent the activity data successfully and which can be used to predict the MnO activities in the compositional range of this study were developed. The MnO activity data was interpreted in terms of a slag model which describes the thermodynamic properties of the slag successfully. 相似文献
7.
The effect of MgO, Al2O3 and CaO/SiO2 on the viscosity of CaO–SiO2–Al2O3–MgO–5 wt-% TiO2 slag was studied in the temperature range of 1673–1773?K. At a fixed CaO/SiO2 ratio of 1·17 and 12 wt-% Al2O3, the viscosity of the slag decreased with increasing MgO content because of depolymerisation of the silicate structures. At a fixed CaO/SiO2 ratio of 1·17 and 8 wt-% MgO, the viscosity of the slag increased with increasing Al2O3 content. At 8 wt-% MgO and 12 wt-% Al2O3 wt-%, increasing the CaO/SiO2 ratio from 1·07 to 1·50 resulted in lower slag viscosity. The temperature dependencies of the viscosity on MgO addition, Al2O3 addition, and CaO/SiO2 ratio were analyzed, and the apparent activation energies of each system were found to be between 178 and 232?kJ/mol, 273 and 360?kJ/mol, and 204 and 233?kJ/mol, respectively. Five different viscosity models were employed to predict slag viscosity, and the Riboud model was found to be the best for predicting this parameter. 相似文献
8.
《钢铁冶炼》2013,40(1):20-25
AbstractThree high basicity slags (A, B and C) were used in laboratory to refine Al killed steel to target high oxide cleanliness and low melting temperature inclusions. Inclusions were of CaO–MgO–Al2O3–SiO2 system after 90 min reaction, parts of which were MgO based. Total oxygen were in the range of 0·0007–0·0010 and 0·0005–0·0010% respectively when slag A (CaO/SiO2, 6–8; Al2O3, ~40%) and slag B (CaO/SiO2, 6–8; Al2O3, ~30%) were applied, with inclusions all in spherical shape and mainly <5 μm. Inclusion composition concentrated in or around the lower melting point region (<1500°C) under slag A, while it became more scattered under slag B. Total oxygen varied between 0·0008 and 0·0011% under slag C (CaO/SiO2, 3–4; Al2O3, about 20–25%). Many of the inclusions were in larger size, irregular morphology and located far away from the lower melting point region. Formation of MgO based inclusions closely related to solubility behaviour of MgO in the slag. 相似文献
9.
Qifeng Shu 《国际钢铁研究》2009,80(2):107-113
A model for viscosity estimation of molten slags in the Al2O2‐CaO‐MgO‐SiO2 system is presented in this work. The model is an extension to the viscosity estimation model of molten slags in the CaO‐FeO‐MgO‐MnO‐SiO2 system developed before by the present author. The present model has explicitly taken charge compensation into consideration. It is postulated that Al exists in a structural unit MAl2O4 when MO/ Al2O3 >1 for the Al2O3‐MO‐SiO2 system (MO=CaO, MgO). MAl2O4 has a similar behaviour as SiO2, i.e. it can form an Al‐O‐Al network and be depolymerised by network modifying oxides (CaO, MgO). The present model is applied in viscosity estimation of some slags within the Al2O3‐CaO‐MgO‐SiO2 system. A mean deviation of less than 25% is achieved for the present model. 相似文献
10.
S. A. Nightingale B. J. Monaghan G. A. Brooks 《Metallurgical and Materials Transactions B》2005,36(4):453-461
Experiments based on exposure of MgO to slags under forced convection flow conditions allowed the identification of different
degradation mechanisms and the assessment of the role of Al2O3 in the degradation process. Slag with no alumina present resulted in direct dissolution. Samples immersed in alumina containing
slag underwent indirect dissolution, with a spinel forming at the MgO-slag interface. At 1530 °C, the spinel was not effective
in reducing the corrosion rate, as the scattered spinel grains were easily removed from the MgO surface. At 1500 °C, the loss
of MgO was reduced due to the formation of a more cohesive spinel layer. Mechanical erosion then appears to play a greater
role. Strength of the bond between the spinel and underlying MgO needs to be considered in strategies to reduce degradation
of MgO refractories. 相似文献
11.
In CaO–Al2O3- and CaF2–CaO–Al2O3-slags the soluted water vapour was quantitatively determined with Fourier-Transform-lnfrared-(FT-IR-)spectroscopy. The slags were equilibrated at 1500 and 1600 °C with definite H2O- and H2O/HF-partial pressures, respectively. The liquid slags were quenched in liquid D2O. They solidified glassily. Water vapour exists in the slags soluted as OH?-ion. For all slags investigated a linear dependence of the integral extinction upon the square root of the H2O-partial pressure, respectively upon HF-partial pressure, was determined. The values of the integral extinction (CaF2–CaO–Al2O3-slags) are calibrated by a H2O-doping-technique. The solution enthalpy of H2O in CaO–Al2O3-slags was estimated: endothermal reactions. Interpretation of the vibrational range yielded in a mainly tetrahedral coordination of Al3+ with O2?- and F? -ions in the glassy state. By heating the glassily solidified CaO–Al2O3-slags were transformed into their crystalline products: shifting of IR-peaks. The CaO–Al2O3- and CaF2–CaO-slags were compared with a CaO–SiO2–Al2O3-slag. The FT-IR-method is quick. The water content can be estimated with an uncertainty of less than ± 5% and is, therefore, suitable for process control of metallurgical procedures. 相似文献
12.
HSC 6.1 Chemistry software (Outokumpu) and a simplex–lattice experiment design are employed in thermodynamic modeling of the equilibrium boron distribution between steel containing 0.2% C, 0.35% Si, and 0.028% Al (wt % are used throughout) and CaO–SiO2–Al2)3–8% MgO–4% B2O3 slag over a broad range of chemical composition at 1550 and 1600°C. For each temperature, mathematical models (in the form of a reduced third-order polynomial) are obtained for the equilibrium boron distribution between the slag and the molten metal as a function of the slag composition. The results of simulation are presented as graphs of the composition and equilibrium distribution of boron. The slag basicity has considerable influence on the distribution coefficient of boron. For example, increase in slag basicity from 5 to 8 at 1550°C decreases the boron distribution coefficient from 160 to 120 and hence increases the boron content in the metal from 0.021% when L B = 159 to 0.026% when L B = 121. In other words, increase in slag basicity favorably affects the reduction of boron. Within the given range of chemical composition, the positive influence of the slag basicity on the reduction of boron may be explained in terms of the phase composition of the slag and the thermodynamics of boron reduction. Increase in metal temperature impairs the reduction of boron. With increase in temperature to 1600°C, the equilibrium distribution coefficient of boron increases by 10, on average. On the diagrams, we see regions of slag composition with 53–58% CaO, 8.5–10.5% SiO2, and 20–27% Al2O3 corresponding to boron distribution coefficients of 140–170 at 1550 and 1600°C. Within those regions, when the initial slag contains 4% B2O3, we may expect boron concentrations in the metal of 0.020% when L B = 168 and 0.023% when L B = 139. 相似文献
13.
The empirical models of sulfide capacity calculated by traditional optical basicity do not consider the charge compensation of alkaline metal ions to Al3+ in the molten slags, so that the deviations between the calculated values and measured ones of sulfide capacity are inevitable. The relation between sulfide capacity and the corrected optical basicity put forward by Mills considering the charge compensation was investigated. Combined with the relation between sulfide capacity and temperatures, a novel and accurate calculation model of sulfide capacity was proposed, which was applied to calculate the sulfide capacities of CaO-Al2O1-SiO2-MgO and CaO-Al2O1-SiO2-MgO-TiO2 systems, where the sum of the CaO and MgO concentrations in the slags must be not lower than the Al2O3 concentration. It was also found that the calculated values were in a good agreement with the measured values, and the mean deviations were 2. 57% and 2. 65%, respectively. 相似文献
14.
The effects of MgO and FeO contents on the sulphide capacity of Corex slags were investigated at 1773 K using gas/slag equilibrium technique as a fundamental study for stabilising Corex operational conditions. The gradual substitution of MgO for CaO at a fixed basicity [B = {(%CaO)+(%MgO)}/(%SiO2)] decreased the sulphide capacities of CaO-SiO2-Al2C3-MgO slags. The addition of FeO into the CaO-SiO2-Al2O3-MgO slags at the fixed (%CaO)/(%SiO2) ratio, MgO and Al2O3 contents significantly increased the sulphide capacities. The sulphide capacity decreased according to the increasing Al2O3 content at the fixed (%CaO)/(%SiO2) ratio, MgO and FeO content. Based on the previously reported and present values of sulphide capacities, the sulphide capacity as a function of slag composition on the mole fraction base at 1773 K was expressed by the formula of log CS = XCaO – 3.89 XSiO2 – 3.18 XAl2O3 – 0.55 XMgO + 2.43 XFeO – 2.61. In addition, the relationship between the sulphide capacity and optical basicity could be represented as the formula of log CS = 12.51 A – 12.24 and the theoretical optical basicity of FeO was found be 0.94 from the correlation. The effect of FeO on the sulphur distribution ratio was estimated using the present sulphide capacity values and the oxygen activity in liquid iron, which could be determined with the help of Fe/FeO equilibrium. FeO activity in slag was well described by the quadratic formalism based on the regular solution model. The sulphur distribution ratio according to FeO content varies in an opposite way, compared with that of the sulphide capacity. 相似文献
15.
The activities of SiO2 and Al2O3 in CaO-SiO2-Al2O3-MgO slags were determined at 1873 K along the liquidus lines saturated with 2CaO · SiO2, 2(Mg,Ca)O · SiO2, MgO, and MgO · Al2O3 phases using a slag-metal equilibration technique. Based on these and previous results obtained in ternary and quaternary
slags, the isoactivity lines of SiO2 and Al2O3 over the liquid region on the 0, 10, 20, 30, and 40 mass pct Al2O3 planes and those on the 10 and 20 mass pct MgO planes were determined. The activity coefficients of Fe
t
O and MnO, the phase boundary, and the solubility of MgO were also determined. 相似文献
16.
Mao Chen Sreekanth Raghunath Baojun Zhao 《Metallurgical and Materials Transactions B》2013,44(4):820-827
The present study delivered the measurements of viscosities in SiO2-“FeO”-Al2O3 system in equilibrium with metallic Fe. The rotational spindle technique was used in the measurements at the temperature range of 1473 K to 1773 K (1200 °C to 1500 °C). Molybdenum crucibles and spindles were employed in all measurements. The Fe saturation condition was maintained by an iron plate placed at the bottom of the crucible. The equilibrium compositions of the slags were measured by EPMA after the viscosity measurements. The effect of up to 20 mol. pct Al2O3 on the viscosity of the SiO2-“FeO” slag was investigated. The “charge compensation effect” of the Al2O3 and FeO association has been discussed. The modified quasi-chemical viscosity model has been optimized in the SiO2-“FeO”-Al2O3 system in equilibrium with metallic Fe to describe the viscosity measurements of the present study. 相似文献
17.
The viscosities of CaO‐SiO2‐20 wt%Al2O3‐MgO slags (CaO/SiO2 = 1.0–1.2, wt%MgO = 5–13) were measured to estimate the effect of MgO on the viscous behaviour at elevated temperatures. The slag viscosity at 1773 K decreased with increasing MgO contents, which was typical of a basic oxide component at relatively low basicity (CaO/SiO2) of 1.0. The FT‐IR spectroscopic analysis of the slag structure seems to verify this behaviour. However, an unexpected contradiction with the temperature dependence was observed above 10 wt%MgO and above CaO/SiO2 of 1.2. Although the apparent activation energy was expected to decrease with additions of the basic oxide component MgO, the apparent activation energy increased. This unexpected behaviour seems to be related to the change in the primary phase field correlating to the phase diagram corresponding to the slag composition. Therefore, in order to understand the viscosity at both high Al2O3 and MgO, not only should the typical depolymerization of the slag structure with high MgO content be considered but also the primary phases of which the molten slag originates. 相似文献
18.
Viscosities of B2O3 and TiO2‐bearing fluoride‐free mold fluxes have been measured by the rotating cylinder method in this work. Effects of different B2O3, TiO2 content, and basicities on the viscosity characteristics have been examined. Viscosity of fluoride‐free mold fluxes containing B2O3 and TiO2 was found to decrease with the increase of B2O3, TiO2 content, and basicity. The values of apparent activation energy for viscous flow of slags decrease with additions of B2O3 and TiO2 and the increase of basicity. Two parameters A and B in Riboud model were re‐evaluated based on the present experimental data, and the modified Riboud model was used to estimate the viscosity of fluoride‐free slag system investigated in present work. The viscosity values obtained by the experimental measurement were in good agreement with those calculated by the modified Riboud model. 相似文献
19.
The values of the activity of Cr2O3 in the slags based on the CaF2−CaO−Cr2O3 and the CaF2−Al2O3−Cr2O3 systems which may be used in the electroslag remelting (E.S.R.) process have been determined at 1450, 1500 and 1550°C by
equilibrating the slags with Pt−Cr alloys of known chromium activity under known oxygen partial pressure and studying the
equilibrium 2[Cr] alloy+3/2 O2(g)=(Cr2O3)slag. It was found that activity of Cr2O3 decreases with the addition of CaO and Al2O3 in the respective systems. In slags containing less than about 20 wt pct CaO and in the Al2O3 bearing slags, solutions of Cr2O3 showed a positive deviation from ideality and in slags containing more than 20 wt pct CaO, they showed a negative deviation.
Both the authors were formerly with the Department of Metallurgy, University of Sheffield, England 相似文献
20.
Metal-slag refining reactions have been investigated to determine dephosphorization equilibria in steelmaking using CaO-saturated slags, low in P2O5–content, based on the systems FeOn–CaO–SiO2 and FeOn–CaO–Al2O3. Slag compositions have been optimized with respect to basicity and oxygen potential to achieve maximum partition ratios wt.%(P2O5)/wt.%[P] and minimum phosphorus contents in pure molten iron at 1550, 1600 and 1700°C. Both slag systems prove to be effective dephosphorizers. Optimal slag compositions are around 10 wt.% SiO2 near the CaO–3CaO · SiO2 double saturation in the case of FeOn–CaO–SiO2 slags and at Al2O3 contents tending to zero in the case of FeOn–CaO–Al2O3 slags. Attempts were also made to present phosphate capacities CPO43?, fractions of free oxygen ions xO2? and theoretical optical basicities Λ as a function of the FeOn content of slags. 相似文献