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1.
The solubility of nitrogen as the nitride ion in CaO-SiO2-Al2O3 slags in equilibrium with N2-CO gas mixtures and carbon was measured at 1823 K. The nitride capacity (C
N3-) was calculated to compare the nitrogen contents measured under different nitrogen and oxygen potentials.C
N3- decreased with increasing basicity and by replacing SiO2 with A12O3. The nitrogen partition ratio between carbon saturated iron and the slag was measured in CO gas at one atmosphere at 1823
K. By comparing the partition ratios with the corresponding nitride capacities measured by the gas-slag experiments, it was
concluded that the oxygen partial pressure at the slag-metal interface was controlled by the Fe-FeO reaction. A new definition
of nitride capacity was proposed based on the reaction between nitrogen and the network former,i.e., SiO2 or A12O3. This capacity could consistently explain the experimental results. Empirical equations were derived to estimate the activity
coefficients of silicon and aluminum nitrides in the slags.
On leave of absence from the Research Institute of Mineral Dressing and Metallurgy, Tohoku University, Sendai, Japan. 相似文献
2.
The solubility of carbon in molten CaO-B2O3 and BaO-B2O3 slags at high temperatures was measured to understand the dissolution mechanism of carbon into the slags. The B2O3-bearing slags, which have a wide range of liquids, at the temperature of interest have been applied to investigate the effect
of basicity on the solubility of carbon from the saturation of acidic or basic components. The solubility of carbon, as a
function of the composition of slags, shows a minimum value, and it is suggested that carbon dissolves by different mechanisms
in the acidic and basic slags, respectively. From the infrared spectra measurements, the wave number indicating the B-C bond
was found to be about 1150 cm−1 in the acidic region of slags; hence, the incorporation of carbon into the borate network was confirmed qualitatively. The
carbide capacity was compared to the nitride capacity, showing that the dissolutions of carbon and nitrogen into the slags
are similar. 相似文献
3.
Klaus Schwerdtfeger Hans Georg Schubert 《Metallurgical and Materials Transactions B》1977,8(3):535-540
CaO-Al2O3 slags were melted in graphite crucibles under N2-CO-Ar gas mixtures at 1600°C. The contents of total nitrogen, cyanide and total carbon of the slags were determined by chemical
analyses of quenched samples taken by suction from the melt. The nitrogen is present in the melt as nitride N3- ion and cyanide CN-1 ion, and carbon as cyanide and carbide C2- ion. The equilibrium constants for the respective reactions were evaluated. It is found that the nitride capacity of the
melt decreases whereas the cyanide and carbide capacities increase with increasing CaO/Al2O3 ratio. 相似文献
4.
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
5.
Sulfide capacity of CaO-CaF2-SiO2 slags 总被引:1,自引:0,他引:1
Katsujiro Susaki Masafumi Maeda Nobuo Sano 《Metallurgical and Materials Transactions B》1990,21(1):121-129
The sulfide capacityC
S
2- = (pct S2-) · (P
O
2/P
S
2)1/2) of CaO-CaF2-SiO2 slags saturated with CaO, 3CaO · SiO2 or 2CaOSiO2 was determined at 1200 °C, 1250 °C, 1300 °C, and 1350 °C by equilibrating molten slag, molten silver, and CO-CO2 gas mixtures. Higher sulfide capacities were obtained for CaO-saturated slags. A drastic decrease was observed in those values
when the ratio pct CaO/pct SiO2 is less than 2. The sulfur partition between carbon-saturated iron melts and presently investigated slags was calculated
by using the sulfide capacities obtained and the activity coefficient of sulfur in carbon-saturated iron, which was also experimentally
determined. For slags saturated with CaO, partitions of sulfur as high as 10,000 were obtained at 1300 °C and 1350 °C. Correlations
between the sulfide capacity and other basicity indexes such as carbonate capacity and theoretical optical basicity were also
discussed.
Formerly with the Department of Metallurgy, The University of Tokyo. 相似文献
6.
Nitrogen distribution ratios, LN ( = (mass pct N)/[mass pct N]), between CaO-SiO2-Al2O3 slags and liquid iron were measured at 1823 and 1873 K as a function of Si (or Al) content in metal, using lime and alumina
crucibles. Based on these results and the reported values for activities of SiO2 (or Al2O3), nitride capacities, C(N), defined by (mass pct N) · PO2/3/4/PN2/1/2 were evaluated. Activities of SiO2 (or Al2O3) obtained by using the values for LN and C(N) obtained in present and previous gas-slag experiments were compared with previous results.
FUMIHIKO TAMURA formerly Graduate Student with the Department of Metallurgical Engineering, Tohoku University. 相似文献
7.
The nitrogen partition ratio between Na2O-SiO2 slags and carbon saturated iron was measured for slags containing from 0.4 to 0.55 mole fraction of Na2O and the temperature range 1200° to 1350 °C. The nitrogen is dissolved in the slag as the cyanide ion (CN−) and the partition ratio is proportional to the oxygen pressure to the −1/4 power as predicted for CN− dissolution. The oxygen pressure for carbon saturated iron silicon alloys is controlled by the Si (metal)-SiO2 (slag) equilibrium. The nitrogen partition ratio and the cyanide capacity increase with Na2O content and temperature. Calculations indicate that Na2O-SiO2 slags will absorb three times more nitrogen than CaO-Al2O3 slags at the same basicity and temperature. Based on thermodynamic calculations it is estimated that for a typical Na2CO3 hot metal treatment, half of the nitrogen in the metal could possibly be removed.
F.Tsukihashi is on leave of absense from Department of Metallurgical Engineering and Materials Science, Faculty of Engineering,
The University of Tokyo, Bunkyo, Tokyo 113, Japan 相似文献
8.
9.
The nitrogen solubility and nitride capacity of the BaO-B2O3 and CaO-B2O3 systems were measured at 1698 and 1773 K, respectively, using a gas-liquid equilibration technique. These systems were chosen
because they have wide liquidus regions at the temperature of interest and were expected to show two types of nitride solution
behavior. The nitride capacities of both systems showed minimum values with changing composition. This was explained by considering
that nitrogen can dissolve into slag as “free nitride” at high basicities and as “nitride incorporated” with the network for
acidic slags. The change of the nitride capacity with optical basicity and the activity of the basic component followed the
predicted behavior for the proposed solution mechanism. The nitride capacity of the BaO-B2O3 system is considerably greater than for the CaO-B2O3 system because BaO is a more basic oxide than CaO. The activity of BaO in the BaO-B2O3 system was also measured by equilibration with liquid silver, at known oxygen potentials, and the activities show large negative
deviations from ideal behavior. 相似文献
10.
The sulphide capacities (CS) of CaO–SiO2–Al2O3–MgO–TiO2 blast furnace slags were experimentally measured at 1773?K, and the percentages of free oxygen ions (O2?) and bridge oxygen (O0) of molten slag were calculated using molecular dynamics at 1773?K. The measured and calculated results were closely correlated with the change in CaO/SiO2, MgO, and Al2O3 contents in the slag. The results show that CS increases with increasing CaO/SiO2 and MgO contents in the slag, but decreases with increasing Al2O3 content. The effects of O2? and O0 on CS were analysed using multiple linear regression, and results show that sulphide increases with the increase in the mass percentage of free oxygen and decreases with the increase in the mass percentage of bridge oxygen. 相似文献
11.
Kyoung Jun Myoung Young Seok Lee Dong Joon Min Uoo Chang Chung Sang Ho Yi 《国际钢铁研究》2004,75(12):783-791
The solubility of chlorine in CaO‐SiO2‐Al2O3‐MgO(‐CaF2) slag was measured at 1673 ‐1823 K. By estimating the chloride capacity of slags, thermodynamic behaviour of chlorine in the molten slag was investigated. Chloride capacity increased with increasing CaO / SiO2 ratio (C/S). An increase in MgO content decreased chloride capacity at C/S≥1.0 because it lowered the activity of Ca2+ which seemed to have strong affinity with Cl? in molten slag. Also, the chloride capacity decreased with increasing Al2O3 content. The affinity between the Ca2+ and Cl? ions was confirmed by measuring the infrared spectra of slags. The dissolution reaction of chlorine into slag was exothermic and its molar enthalpy was evaluated from the experimental results at 1673 ‐ 1823 K. Based on the result obtained in the present study, the quantitative prediction of chlorine distribution during the blast furnace process was performed. It was estimated that almost all chlorine in the blast furnace would be absorbed into molten slag even if the PCI ratio was increased or low quality coal with chlorine content less than 1.0 mass% was injected. 相似文献
12.
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
13.
The sulfur partition ratio between slag and carbon saturated iron and the sulfide capacity of CaO-Na2O-SiO2 slags and a 48 pet CaO-45 pet Al2O3-7 pet SiO2-(Na2O) slag have been mea-sured at 1400 °C. The addition of Na2O to a CaO-SiO2 slag increases the sulfur partition ratio and the sulfide capacity; however, Na2O at low concentrations has no measurable effect on the sulfide capacity of a CaO-Al2O3-SiO2 slag. To convert the sulfur partition ratio to the sulfide capacity, the oxygen potential was calculated assuming equilibrium
between iron in the alloy and FeO in the slag with the activity of FeO calculated via a regular solution model. The optical
basicity may be used to correlate the data, but at high Na2O contents the data do not adhere to the correlation previously developed for CaO-based slags.
Formerly Graduate Student at Carnegie Mellon University 相似文献
14.
The solubility of nitrogen and the nitride capacity of CaO-Al2O3-TiO2 and CaO-BaO-Al2O3-TiO2 slags were measured at 1873 K using a gas-slag-metal equilibration technique with carbon-saturated iron and gas mixtures
of CO and N2. The nitride capacity increased with increasing the TiO2 and BaO content and is significantly higher than the nitride capacity for normal ladle slags. The activity coefficient of
TiO2 in CaO-Al2O3-TiO2 and CaO-BaO-Al2O2-TiO2 systems were measured. This is necessary to know in order to estimate the possible pickup of titanium in the metal when an
aluminum-killed steel is treated with these slags. Also, the activity coefficient of Ti in carbon-saturated iron was measured.
The kinetics of the nitrogen reaction between slag and metal is influenced by the oxygen potential in the metal and is primarily
controlled by liquid-phase mass transfer of nitrogen in the metal.
Formerly with the Department of Metallurgical Engineering and Materials Science, Carnegie Mellon University 相似文献
15.
Xue-Min Yang Jian-Ping Duan Cheng-Bin Shi Meng Zhang Yong-Liang Zhang Jian-Chang Wang 《Metallurgical and Materials Transactions B》2011,42(4):738-770
A thermodynamic model for calculating the phosphorus distribution ratio between top–bottom combined blown converter steelmaking
slags and molten steel has been developed by coupling with a developed thermodynamic model for calculating mass action concentrations
of structural units in the slags, i.e., CaO-SiO2-MgO-FeO-Fe2O3-MnO-Al2O3-P2O5 slags, based on the ion and molecule coexistence theory (IMCT). Not only the total phosphorus distribution ratio but also
the respective phosphorus distribution ratio among four basic oxides as components, i.e., CaO, MgO, FeO, and MnO, in the slags and molten steel can be predicted theoretically by the developed IMCT phosphorus distribution
ratio prediction model after knowing the oxygen activity of molten steel at the slag–metal interface or the Fe
t
O activity in the slags and the related mass action concentrations of structural units or ion couples in the slags. The calculated
mass action concentrations of structural units or ion couples in the slags equilibrated or reacted with molten steel show
that the calculated equilibrium mole numbers or mass action concentrations of structural units or ion couples, rather than
the mass percentage of components, can present the reaction ability of the components in the slags. The predicted total phosphorus
distribution ratio by the developed IMCT model shows a reliable agreement with the measured phosphorus distribution ratio
by using the calculated mass action concentrations of iron oxides as presentation of slag oxidation ability. Meanwhile, the
developed thermodynamic model for calculating the phosphorus distribution ratio can determine quantitatively the respective
dephosphorization contribution ratio of Fe
t
O, CaO + Fe
t
O, MgO + Fe
t
O, and MnO + Fe
t
O in the slags. A significant difference of dephosphorization ability among Fe
t
O, CaO + Fe
t
O, MgO + Fe
t
O, and MnO + Fe
t
O has been found as approximately 0.0 pct, 99.996 pct, 0.0 pct, and 0.0 pct during a combined blown converter steelmaking
process, respectively. There is a great gradient of oxygen activity of molten steel at the slag–metal interface and in a metal
bath when carbon content in a metal bath is larger than 0.036 pct. The phosphorus in molten steel beneath the slag–metal interface
can be extracted effectively by the comprehensive effect of CaO and Fe
t
O in slags to form 3CaO·P2O5 and 4CaO·P2O5 until the carbon content is less than 0.036 pct during a top–bottom combined blown steelmaking process. 相似文献
16.
The nitrogen solubility and nitride capacity of a Na2O‐B2O3 slag system were investigated in a concentration range of Na2O mass contents up to 40 % at 1373K. The solubility of nitrogen in Na2O‐B2O3 slag was found to be proportional to the oxygen partial pressure to the power of ?3/4, and it was also found to increase with increasing reaction temperature. The nitride capacity of the slag decreased with increasing Na2O content. From the experimental results it was concluded that nitrogen dissolution into Na2O‐B2O3 slags (Na2O mass contents < 40 %) occurs by its reaction with both free oxygen ions and with oxygen ions incorporated with the network. 相似文献
17.
Using a gas-slag-metal equilibration technique, nitrogen contents in BaO-TiO^ slags and nitrogen and titanium contents in
liquid Cu were measured at 1823, 1873, and 1923 K under controlled partial pressures of oxygen(@#@ PO
2 = 10-11.5 ≈ 10-13.7 atm) and nitrogen(@#@ PN
2 = 0.9 atm). The nitride capacity, C(N) [=(mass pct N) · PO2/3/4, (mass pct Ti3+)/(mass pct Ti4+) ratio, and solubility of TiN in BaO-TiO2-TiO1.5 slags were obtained as a function of slag com-position(@#@ XBaO
= 0.20 = 0.43) and temperature. Activity coefficients of TiN were estimated, using the values for activity coefficients of
Ti in liquid Cu which were calculated from the results of a TiN saturation experiment. Free energy of dissolution of nitrogen
into liquid Cu was derived as °GGN
o = 32,400 + 46.17 ± 1400 (J/g · atom). 相似文献
18.
Klaus Schwerdtfeger Hans Georg Schubert 《Metallurgical and Materials Transactions B》1977,8(4):535-540
CaO-Al2O3 slags were melted in graphite crucibles under N2–CO–Ar gas mixtures at 1600°C. The contents of total nitrogen, cyanide and total carbon of the slags were determined by chemical
analyses of quenched samples taken by suction from the melt. The nitrogen is present in the melt as nitride N−3 ion and cyanide CN−1 ion, and carbon as cyanide and carbide C
2
2−
ion. The equilibrium constants for the respective reactions were evaluated. It is found that the nitride capacity of the
melt decreases whereas the cyanide and carbide capacities increase with increasing CaO/Al2O3 ratio. 相似文献
19.
The rates of reduction of ferric iron in Fe2O3-CaO-SiO2-Al2O3 slags containing 3 to 21 wt pct Fe2O3 under impinging argon, CO-CO2, or H2-H2O have been studied at 1370 °C under conditions of enhanced mass transfer in the slag using a rotating alumina disc just in
contact with the slag surface. For a 6 wt pct Fe slag at a stirring speed of 900 rpm the observed reduction rates by 50 pct
H2-H2O were a factor of 2 to 3 times higher than those by 50 pct CO-CO2 and more than one order of magnitude higher than those under pure argon. The observed rates were analyzed to determine the
rate-controlling mechanisms for the present conditions. Analysis of the rate data suggests that the rates under 50 pct H2-H2O are predominantly controlled by the slag mass transfer. The derived values of the mass-transfer coefficient followed a square-root
dependence on the stirring speed for a given slag and, at a given stirring speed, a linear function of the total iron content
of the slags. The rates of oxygen evolution during reduction under pure argon were shown to be consistent with a rate-controlling
mechanism involving a fast chemical reaction at the interface and relatively slow mass transfer in the gaseous and the slag
phases. The rates of reduction by CO-CO2 (pCO=0.02 to 0.82 atm) were found to be likely of a mixed control by the slag mass transfer and the interfacial reaction. A
significant contribution of oxygen evolution to the overall rates was observed for more-oxidized slags and for experiments
with relatively low values of pCO. Assuming a parallel reaction mechanism, the estimated net reduction rates due to CO were found to be of the first order
in pCO, with the first-order rate constants being approximately a linear function of the ferric concentration.
This article is based on a presentation made in the “Geoffrey Belton Memorial Symposium” held in January 2000, in Sydney,
Australia, under the joint sponsorship of ISS and TMS. The original symposium appeared in the October 2000 Vol. 31B issue. 相似文献
20.
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