共查询到20条相似文献,搜索用时 156 毫秒
1.
Activity coefficients of MnO and Fe,0 in CaO-SiO2-Al2O3-MnO(<10 mass pct)-Fe,O(<3 mass pct) slags were determined at 1873 K in an Al2O3 or CaO crucible by using the reported values for the activities of Al2O3 and SiO2 or the analyzed contents of oxygen. The activity coefficients of MnO and FetO were found to be constant in the studied concentration range of MnO and FetO. The former increased with an increase in the CaO content, while the latter increased with an increase in the SiO2 content. 相似文献
2.
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
3.
The effect of oxide component content on the low melting point zone (simplified as LMP) in the CaO‐MnO‐Al2O3‐SiO2 system has been analysed by FactSage. The contents of [Si], [Mn], [O] and [Al] in liquid steel which are in equilibrium with the LMP inclusions in the CaO‐MnO‐Al2O3‐SiO2 system have been calculated. The results show that the CaO‐MnO‐Al2O3‐SiO2 system has the largest LMP zone (below 1400°C) when the Al2O3 content is 20% or the CaO content is 15%, and that the LMP zone becomes wider with increase in SiO2 and MnO contents (within the range of 0~25%). To obtain LMP inclusions (below 1400°C), [Si] and [Mn] can be controlled within a wide range, but [Al] and [O] must be controlled within the range of 0.5~5 ppm and 50~120 ppm, respectively. 相似文献
4.
The thermodynamics of distribution of constituents between liquid iron and the CaO–Al2O3–SiO2–FeO–MnO system at 1600°C was studied using electrochemical indication of the equilibrium partial pressure of oxygen in both phases. The results show that oxidation potential of the Fe(l)–CaO–Al2O3–SiO2–FeO–MnO system, expressed in terms of log p(O2), is directly proportional to log (x(MnO) · x(FeO)/w| Mn |). Manganese distribution coefficient, L'mn, in intersection CaO/Al2O3 = 1 decreases with increasing slag basicity expressed in terms of activity a(CaO) or 1/γ(MnO). Experimentally determined equilibrium constant KMn/Fe is equal to 2.7 for 1600°C. The number of exchanged electrons between Fe-O-Mn-Si electrode and the slag approaches the theoretical value. 相似文献
5.
Electrochemical measurements of the solid-oxide galvanic cell Mo/Mo + MoO2/ZrO2(MgO)/Fe + (FexO + A12O3 + SiO2)slag/Ag/Fe have been made at 1673 K in order to obtain the activities of FexO in FexO + A12O3 + SiO2 slags. Activities of A12O3 and SiO2 were also determined by virtue of Gibbs-Duhem integration. By using the activity data, the free energies of formation of
hercynite and mullite were also obtained.
Leave of absence from the Steelmaking Research Section, Iron and Steel Research Laboratories, Kobe Steel Ltd. 相似文献
6.
The thermodynamic equilibria of manganese and phosphorus between liquid iron and CaO‐MgOSat‐SiO2‐FetO‐MnO‐P2O5‐Al2O3 (0–33%) ladle slag have been investigated at 1873 K from the viewpoint of Mn and P yields for the production of high‐strength steels. The equilibrium distribution ratios of Mn and P were found to increase with increasing FetO content; however, these ratios vary with basicity, but they do this the other way round. The addition of alumina into slag at a fixed basicity and FetO content decreases both the equilibrium manganese and phosphorus distributions. The equilibrium distribution ratios were discussed in terms of the variation of activity coefficients of FetO, MnO and PO2.5, according to the slag basicity and Al2O3 content. The quantitative contributions of basicity and (%FetO + %MnO) on LMn and LP were empirically determined and their usefulness was discussed with the aid of plant data: To improve Mn and P yields in the practical RH operation, it is strongly recommended that Fe‐Mn and Fe‐P alloys be added after Al deoxidation treatment inducing relatively high Al2O3 in slag and maintaining low FetO content. In addition, a ladle slag composition for the targeted Mn and P contents in liquid iron was substantially estimated using the empirical relationships. 相似文献
7.
The activity coefficients of FetO in CaO-Al2O3 and CaO-Al2O3-SiO2 slags with 0.01 to 5 mass pct FetO were determined at 1873 K from the data obtained in the present and previous slag-metal experiments, using an alumina or
lime crucible. It was found that the activity coefficients of FetO obeyed a dilute solution law and increased with increasing the content of SiO2. Based on the findings pertaining to the activity coefficient, the values for the activities of SiO2 and Al2O3 in CaO-Al2O3-SiO2 slags were assessed. 相似文献
8.
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
9.
Marissa Vargas‐Ramirez Antonio Romero‐Serrano Federico Chavez‐Alcala Beatriz Zeifert Manuel Hallen‐Lopez 《国际钢铁研究》2002,73(9):378-384
This work estimated the reduction of MnO in slags of the CaO‐SiO2‐FeO‐CaF2‐MnO system and liquid steel with the initial composition (mass contents) 0.75 %Mn, 0.16 % Si and 0.5 to 2.0 % C, as an alternative to introducing Mn to the steel melt. The slag basicities (CaO/SiO2) In the experiments were 2 and 3. MnO was obtained from manganese ore. The experiments were carried out in an open 10 kg induction furnace using Al2O3‐based refractory at 1873 K. The oxygen potential was measured throughout the experiments with a galvanic cell (ZrO2‐solid electrolyte with a Cr/Cr2O3 reference electrode). The MnO reaction mechanism was analysed in terms of the slag basicity, the silicon and the initial carbon contents in the melt. The rate and the degree of MnO reduction were found to increase with the increasing of initial carbon content; however, the effect of slag basicity was less important. A kinetic analysis of the process was performed using a coupled reaction model. 相似文献
10.
Ghasem Roghani Evgueni Jak Peter Hayes 《Metallurgical and Materials Transactions B》2002,33(6):827-838
Phase relations and the liquidus surface in the system “MnO”-Al2O3-SiO2 at manganese-rich alloy saturation have been investigated in the temperature range from 1373 to 1773 K. This system contains
the primary-phase fields of tridymite and cristobalite (SiO2); mullite (3Al2O3·2SiO2); corundum (Al2O3); galaxite (MnO·Al2O3); manganosite (MnO); tephroite (2MnO·SiO2); rhodonite (MnO·SiO2); spessartine (3MnO·Al2O3·SiO2); and the compound MnO·Al2O3·2SiO2. 相似文献
11.
Measurements of the activities of FexO in complex slags during the final stages of external dephosphorization by using a disposable electrochemical oxygen probe. Positive deviations of the FexO activities from the Raoult law. Iso-activity curves drawn on the “ternary” diagram, (CaO + MgO + MnO + CaF2) + FexO + (SiO2 + P2O5) at 1673 K. Calculations of the activities of P2O5 in complex slags with an assumption of thermodynamic equilibrium between slags and hot metal. Beneficial effect of CaF2 in the slags with respect to lowering of the P2O5 activity. 相似文献
12.
《Canadian Metallurgical Quarterly》2013,52(3):309-322
AbstractData from the literature were used to construct activity diagrams for the systems Mn–Fe–C, MnO–CaO–SiO2 and CaO–Al2O3–SiO2 with 10% MnO. Assuming that the reduction temperature is close to slag melting point, the MnO content required to obtain a 75% Mn alloy can be found. One can also calculate the Si content corresponding to the slag composition. Fixing the allowable %Si it is found that the slag will contain more than 25% MnO in the MnO–CaO–SiO2 system. The effect of CO pressure is minor. If it is practical to add Al2O3 to the slag, its melting point can be lowered sufficiently to obtain slags with 10% MnO in the CaO–Al2O3–SiO2 system while keeping Si in the metal low. Résumé Des données de la littérature ont été employées pour construire les diagrammes d'activité des systèmes Mn–Fe–C, MnO–CaO–SiO2, et CaO–Al2O3–SiO2 it 10% de MnO. En admettant que la température de la zone de réduction est proche de celle de fusion du laitier, on trouve la teneur en MnO nécessaire pour obtenir l'alliage à 75% de Mn. La quantité de Si réduit a également été déterminée. Le calcul montre qu'en fixant la teneur finale silicium à moins de 0.5% la teneur en MnO doit être supérieure à 25% . dans les laitiers MnO–CaO–SiO2. La pression de CO n'a guere d'effet. S'il est pratique d'ajouter du Al2O3 au laitier pour en abaisser le point de fusion on peut obtenir avec un laiter it 10 % de MnO un alliage pour lequelle Si ne dépasse pas les bornes permises. 相似文献
13.
The thermal conductivity of the mould fluxes containing transition metal oxides was measured by hotline method at different temperatures. The relationship between the thermal conductivity of mold fluxes and the contents of transition metal oxides was discussed. The synthetic slags were composed of 30.0% — 35.4% CaO, 34.7% — 38.6% SiO2, 6% Al2O3, 9% Na2O, 14.4% CaF2, 0–4% Cr2O3 and 0–8% MnO in mass percent. The results indicated that Cr2O3 and MnO had a negative effect on thermal conductivity of mold fluxes. The thermal conductivity of mold fluxes was about 0.25 — 0.55 W/(m K) when the temperature reached 1300 °C, and it increased sharply to about 1.32–1.99 W/(m K) when the temperature reduced from 1300 to 1000 °C. The thermal conductivity of mold fluxes containing Cr2O3 and MnO was 10%—25% lower than those of original fluxes. The decrease in thermal conductivity was attributed to the change of molecular structure of mold fluxes. In addition, the poor integrity and regulation of polycrystal structure, complexity of crystal structure, and effects of impurities in the boundary and lattice distortion leaded to the reduction in the thermal conductivity. Na2CrO4, Mn2SiO4 and other minor phases were also found in the samples containing Cr2O3 and MnO, respectively. 相似文献
14.
For demanding wire applications steel cleanliness should be very high and the inclusions inevitably found in steel should be harmless. This means strict control of inclusions' size, quantity, and composition, pursuing deformable inclusions in rolling conditions. Primary inclusions are formed during steel treatment in the ladle. Most of these are removed to the ladle slag or on the lining. However, the rest of the inclusions still remain through the successive process stages, and some new inclusions are formed during casting and solidification. Conventionally, deformable inclusions are produced by Si–Mn deoxidation resulting in MnO–SiO2–Al2O3 inclusions. This leaves, however, the oxygen content too high for demanding applications. In order to get really clean steel, the Si deoxidation needs to be strengthened by lowering the activity of SiO2 forming in steel. This can be done by bringing the steel in intimate contact with a slag containing SiO2–MnO–Al2O3 and additionally CaO and some MgO. With this kind of intensified Si deoxidation it is possible to produce steels with low oxygen content having inclusions that will elongate at rolling. In this paper thermodynamic examination of potential slag systems and compositions to equilibrate with steels having medium carbon and high silicon were scrutinized. The optimal slag composition for producing low‐O steels with deformable inclusions was evaluated by using FactSage thermodynamic calculation program. The lowest SiO2 activities at the region in which slag is still liquid at 1400°C, can be found when slag composition is approximately 36–40 wt% SiO2, 6–18 wt% Al2O3, 30–40 wt% CaO, 6–8 wt% MgO, and 2–4 wt% MnO. Industrial heats using intensified Si deoxidation and slag based inclusion engineering were produced in a steel mill with 60 tons heat size. Inclusions and slag compositions were in satisfactory accordance with the theoretical examinations, though some scattering was discovered. 相似文献
15.
Dae-Hee Woo Youn-Bae Kang Hae-Geon Lee 《Metallurgical and Materials Transactions B》2002,33(6):915-920
The liquid MnO-SiO2-Al2O3 system was studied at 1823 K by equilibrating MnO-SiO2-Al2O3 melts of different compositions with Pt-Mn alloys and an oxygen-bearing gas phase. Liquid compositions for cristobalite saturation
were determined at 1823 K. A new liquidus for the cristobalite primary field is proposed. The activity of Mn in the Pt-Mn
alloy at 1823 K can be represented by the following equation:
The MnO activity was measured in different melt compositions, and MnO isoactivity lines were determined. It was found that
the MnO activity is relatively insensitive to the SiO2/Al2O3 ratio, but increases sharply above the MnO mole fraction of 0.5. In the low-MnO-concentration range (α
MnO <0.15), the quadratic formalism expressed by the following equation is proposed to represent the MnO activity:
If the MnO activity exceeds the aforementioned limit, the modified quasi-chemical model is recommended. 相似文献
16.
A thermodynamic model for calculating the mass action concentrations of structural units in CaO–SiO2–MgO–FeO–MnO–Al2O3–CaF2 slags, i.e., the IMCT‐Ni model, has been developed based on the ion and molecule coexistence theory (IMCT). The calculated comprehensive mass action concentration of iron oxides $N_{{\rm Fe}_{t} {\rm O}} $ has been compared with the reported activity of iron oxide $a_{{\rm Fe}_{t} {\rm O}} $ in 14 FeO‐containing slag systems from literatures. The good agreement between the calculated $N_{{\rm Fe}_{t} {\rm O}} $ and reported $a_{{\rm Fe}_{t} {\rm O}} $ indicates that the developed IMCT‐Ni model can be successfully applied to predict the activity of iron oxide $a_{{\rm Fe}_{t} {\rm O}} $ as well as the slag oxidation ability of CaO–FeO (s1), SiO2–FeO (s2), CaO–SiO2–FeO (s3), CaO–FeO–Al2O3 (s4), SiO2–MgO–FeO (s5), SiO2–FeO–Al2O3 (s6), CaO–SiO2–FeO–Al2O3 (s7), CaO–SiO2–MgO–FeO–Al2O3 (s8), SiO2–FeO–MnO (s9), SiO2–FeO–MnO–Al2O3 (s10), FeO–MnO (s11), FeO–MnO–Al2O3 (s12), CaO–FeO–CaF2 (s13), and CaO–SiO2–FeO–CaF2 slags (s14) in a temperature range of 1473–1973 K. 相似文献
17.
By using the data in previous and present slag-metal equilibrium experiments, the activities of SiO2 along the liquidus lines in CaO-SiO2-Al2O3 slags were determined at 1823 and 1873 K from the reaction Si+2O=SiO2 (s), in which the oxygen activities were estimated from the measured oxygen contents or from the combination of nitrogen
distribution ratios (L
N) and nitride capacities (C
N). The activities of Al2O3 were also determined from the reaction 2Al+3O=Al2O3 (s), in which the oxygen activities were estimated from the values for L
N and C
N, or from the reaction 3SiO2 (s)+4Al=2Al2O3 (s)+3Si, in which the activities of SiO2 and the contents of Al and Si along with the respective interaction coefficients were used. The activities of Al2O3 and CaO in the entire liquid region were estimated from the Rein and Chipman’s activities of SiO2 by using the method of Schuhmann. On the basis of these activities, the deoxidation equilibria of Si and Al in steels were
discussed. 相似文献
18.
The selective separation phosphorous rich phase from steel slag could be an effective way to utilise the steel slag. The mineralogical phase after cooling of steel slag is essential to selective separation of steel slag. In the present work, the mineralogical phases of CaO–FeOx–SiO2–P2O5 slag after controlled cooling were investigated by X-ray diffraction and scanning electronic microscopy and energy dispersed spectroscopy technique. It was found that the heat treatment at 1573?K would lead to the precipitation of Ca2SiO4–Ca3P2O8 (C2S-C3P) solid solution for all samples. The heat treatment at 1273?K would lead to the precipitation of C2S-C3P, CaSiO3 and Fe2O3. The increase of basicity would promote the crystallisation of CaO–FeOx–SiO2–P2O5 slag. The Effects of additions of MgO and MnO on phase formations of CaO–FeOx–SiO2–P2O5 slag were also studied. Fe2O3 gradually transformed into MgFe2O4 and MnFe2O4 in slag after crystallisation with addition of MgO and MnO, respectively. The sizes of MgFe2O4 and MnFe2O4 crystals increased with increases of MgO and MnO content. The increase of MgO and MnO content would promote the precipitation of MgFe2O4 phase and MnFe2O4, respectively. The precipitation of crystals from slag during cooling was interpreted by the kinetic and thermodynamic factors. It was proposed that addition of MgO and MnO in slag would be beneficial to magnetic separation of steel slag. 相似文献
19.
Min-Su Kim Su-Wan Lee Jung-Wook Cho Min-Seok Park Hae-Geon Lee Youn-Bae Kang 《Metallurgical and Materials Transactions B》2013,44(2):299-308
In order to elucidate the reaction mechanism between high Mn-high Al steel such as twin-induced plasticity steel and molten mold flux composed mainly of CaO-SiO2 during continuous casting process, a series of laboratory-scale experiments were carried out in the present study. Molten steel and molten flux were brought to react in a refractory crucible in a temperature range between 1713 K to 1823 K (1440 °C to 1550 °C) and composition evolution in the steel and the flux was analyzed using inductively coupled plasma atomic emission spectroscopy, X-ray fluorescence, and electron probe microanalysis. The amount of SiO2 in the flux was significantly reduced by Al in the steel; thus, Al2O3 was accumulated in the flux as a result of a chemical reaction, 4[Al] + 3(SiO2) = 3[Si] + 2(Al2O3). In order to find a major factor which governs the reaction, a number of factors ((pct CaO/pct SiO2), (pct Al2O3), [pct Al], [pct Si], and temperature) were varied in the experiments. It was found that the above chemical reaction was mostly governed by [pct Al] in the molten steel. Temperature had a mild effect on the reaction. On the other hand, (pct CaO/pct SiO2), (pct Al2O3), and [pct Si] did not show any noticeable effect on the reaction. Apart from the above reaction, the following reactions are also thought to happen simultaneously: 2[Mn] + (SiO2) = [Si] + 2(MnO) and 2[Fe] + (SiO2) = [Si] + 2(FeO). These oxide components were subsequently reduced by Al in the molten steel. Na2O in the molten flux was gradually decreased and the decrease was accelerated by increasing [pct Al] and temperature. Possible reactions affecting the Al2O3 accumulation are summarized. 相似文献
20.
《钢铁冶炼》2013,40(3):250-257
AbstractA thermodynamic model developed earlier in the present laboratory for oxidic melts was applied to some multicomponent systems, namely CaO–FeO–MgO–SiO2 , Al2 O3–CaO–MgO–SiO2 , Al2 O3–FeO–MnO–SiO2 , and Al2 O3–CaO–FeO–MgO–MnO–SiO2 . Model calculations were carried out using only the parameters corresponding to the binary systems, which, in turn, were based on the available thermodynamic information for these systems. The predicted thermodynamic activities of the component oxides in higher order systems were compared with the experimental data published in the literature. In general, the agreement between the model predictions and the experimental values was found to be satisfactory within the limits of experimental uncertainties and limitations of the model calculations. Examples of model predictions for some typical slag compositions, relevant to the Swedish steel industry and used in the blast furnace, electric arc furnace, and ladle furnace are also presented. 相似文献