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By Yoichi Takeda

Copper solubility in Si02-CaO-FeOx slag equilibrated with copper matte in 10% S02 atmosphere at 1573K was estimated. Essential parameters are activity coefficients of copper oxide and sulfide, oxygen and sulfur potentials and activity of copper in the slag-matte system. A large number of experiments provide proper parameters to calculate copper solubility in slag. A classical thermodynamic model postulating CUOO.5 and CuSo.; molecules assists in estimating copper solubility in slag. Additions of Si02 and CaO reduce copper solubility almost in any condition. Copper loss, that is function copper solubility and slag volume, in the silica saturated Si02-FeOx binary slag is minimally equilibrated with less than 66% copper matte while copper loss in the 50% FeOx-SiOrCaO ternary slag saturated with 2CaOSi02 is minimally equilibrated with over 66% copper matte. This slag composition has potential for continuous copper converting, direct copper production or high-grade matte production.

Jan 1, 2003

By Yoichi Takeda

Copper solubility in SiO2-CaO-FeOx slag equilibrated with copper matte in 10% SO2 atmosphere at 1573K was estimated. Essential parameters are activity coefficients of copper oxide and sulfide, oxygen and sulfur potentials and activity of copper in the slag-matte system. A large number of experiments provide proper parameters to calculate copper solubility in slag, A classical thcrmodynamic model postulating CuO0.5 and CuS0.5 moleculcs assists in estimating copper solubility in slag. Additions of Si02 and CaO reduce copper solubility almost in any condition. Copper loss, that is function copper solubility and slag volume, in the silica saturated SiO2-FeO. binary slag is minimally equilibrated with less than 66% copper matte while copper loss in the 50% FeO.-SiO2-CaO ternary slag saturated with 2CaOSiO2 is minimally equilibrated with over 66% copper matte. This slag composition has potential for continuous copper converting, direct copper production or high-grade matte production.

Jan 1, 2003

By Kimio Itagaki

The distribution behaviours of the VA elements between the gas, slag and matte phases in copper smelting were evaluated on the basis of the thermodynamic data, most of which were determined by the authors. The distribution is basically dependent on the process factors such as temperature, the content of the element in charge, the amount of the waste gas and degree of vapour saturation with the elements. The thermodynamic quantities such as the activity coefficients of the VA elements in matte, the activities of iron and copper, SO2 or 02 potential and the distribution ratio of the elements between the slag and matte phases seriously affect the distribution, and the behaviours in various smelters could be explained systematically and reasonably by considering the changes in these quantities, In oxidation smelting at PSO2= 0.1 to 1 atm, the proportion of arsenic and bismuth in gas is predomi22t for the arsenic and bismuth distributions in both smelting and converting stages. The degree of vapour saturation has serious effect on the distribution, and sufficient contact between gas and matte phases is desirable for transferring arsenic and bismuth into gas phase.The elimination of antimony by means of vaporization is not significant. In reduction smelting at po2 = 10-11 atm, the proportions of arsenic and antimony in the gas phase are quite small, but the proportion of bismuth does not change significantly.

Jan 1, 1983

By C. A. Young, J. D. Miller

Thermodynamic data has been obtained for oleate chemisorption at fluorite (CaF2) and calcite (CaCO3) surfaces using adsorption isotherms determined previously at room and elevated temperatures by in-situ Fourier transform infrared/internal reflection spectroscopy (FT-IR/IRS). Linear regression analysis was used to statistically derive free energy data as a function of temperature assuming oleate chemisorption followed Langmuir-type adsorption. Enthalpy and entropy changes were subsequently ascertained from the Clausius-Clapeyron equation and fundamental thermodynamic relationships. Essentially, no difference in the free energy of chemisorption at the two mineral surfaces was found; however, the differences in enthalpy and entropy values were significant. By comparison, the results showed that oleate chemisorption at fluorite surfaces was more extensive and more entropically driven due to more water being displaced. Results correlate well with values determined in the literature for other mineral collector systems. These findings help explain the greater hydrophobic character of fluorite than calcite in both the absence and presence of oleate.

Jan 1, 2002

By Nestor Cezar Heck

Aim of the present work is to continue the theoretical evaluation of the slags of the fundamental system CaO-SiO2-CrOx-MgO (Ca-O-Cr-Si-Mg quinary system) at the temperature of 1,873 [K], with the help of a computational thermodynamic tool. Driving force for this and the previous research works is the understanding of chromium losses from the molten bath into the slag. Especially motivating is the presence of solid phases in the slag, since they may prevent refractory degradation and help in the production of foaming slags. Nevertheless, Cr-bearing solid phases can lead to Cr losses, being therefore detrimental. Determination of the states of thermodynamic equilibrium for this system using a slag with fixed composition as a start material were made using MgO amount as variable. Results show the impact of the MgO content on the equilibrium phases (molten metal, liquid slag, solids) and their composition for this system.

Jul 30, 2018

By Devon A. Hannan

Thermodynamic modeling calculations were undertaken for the recovery of mercury from HgTe using a vacuum retort reactor. However, discrepancies were noted in the available thermodynamic data which introduced uncertainty in the model results. Consequently, a series of transpiration experiments were first undertaken on the thermal decomposition of HgTe into an inert carrier gas stream according to the following reaction: HgTe(s) Hg(g) + Te(s) From the measured weight loss of the HgTe samples, the Gibhs free energy change for the above volatilization reaction was determined as a function of temperature. The experimentally determined Gibbs free energy values were found to be approximately 30% larger (more posi-tive) than the values available in databases such as HSC Chemistry. By conducting a second-law analysis on the experimental data, the heat of formation of HgTe at 298.15 K and the en-tropyat 298.15 K were determined, which then formed the basis for a new database for the modeling calculations. The results of this study showed that HgTe was more stable at elevated temperatures than was generally indicated in the literature. The new database is given in a for-mat for direct insertion in HSC Chemistry. Using the new database, modeling calculations were conducted to examine the effects of the re-tort pressure and the molar ratio of purge gas to HgTe on the volatilization of mercury from HgTe. A diagram is presented that shows the minimum temperature for 100% volatilization of mercury from HgTe as a function of retort pressure for different molar ratios of purge gas (N2) to HgTe. For example, it was found that the minimum temperature for 100% volatilization could be decreased by 175 K, at a retort pressure of 0.05 bar, if the molar ratio ofN2 to HgTe is increased from 1.0: 1 to 100.0: I.

Jan 1, 2003

By Tan Pengfu

By using computer-aided techniques of equilibrium calculations for multicomponent and multiphase systems, a computer model has been developed to simulate QSL, KIVCET and Outokumpu flash lead smelting processes. A mathematical description is studied using two zones or three zones, namely smelting zone and slag reduction zone for QSL furnace, or offtake shaft zone, smelting shaft zone and electric furnace zone for KIVCET furnace. The amount of each component in lead, slag and gaseous phases under equilibrium is calculated by using the data of free energies of formation and activity coefficients. The predictions by the present computer model are compared with the known data from QSL-Plant at Korea Zinc Co. in Korea, KIVCET-Plant at Nuova Samim Co. in Italy and Outokumpu Co. in Finland. The agreements between the computer predictions and the known data are excellent, so that the present computer model can be used to monitor and optimize the actual industrial operations of direct lead smelting.

Jan 1, 1998

By Pengfu Tan

Lead blast-furnace bullion cools to near its freezing point in an operation known as copper drossing or hot drossing usually contains 0.02-0.06% copper. The removal of this copper is usually carried out in a batch operation known as sulfur drossing. Sulfur is stirred into the bullion at temperatures near its freezing point, and the dross of copper and lead sulfides that floats to the surface is skimmed off manually. A thermodynamic model has been developed to simulate the copper drossing. The phase diagram of Pb-Cu-S system has been calculated, and the effects of the process parameters, such as temperature, copper content, and sulfur content, on the drossing process have been simulated and discussed.

Jan 1, 2006

By Pengfu Tan

A thermodynamic model of KIVCET lead smelting process has been developed. The model has the capability to predict the distribution behaviors of Pb, Zn, Fe, S, O, As, and heat balance in KIVCET direct lead smelting furnace. The compositions of lead bullion, matte, slag and gaseous phases, and heat balance are calculated. The effect of the ratio between oxygen and feed on the chemistry of the smelt and heat balance of the coke checker has been simulated and discussed. The thermodynamic model also helps to understand the tapping issue of the lead bullion. In this paper, some applications of this model in the industry have been presented.

Jan 1, 2006

By Songsong Wang

Recently, replacing Pierce-Smith converting process with the oxygen bottom-blowing continuous converting technology has become a new research focus. Based on the principle of Gibbs free energy minimization, the thermodynamic model of oxygen bottom-blowing continuous converting multiphase equilibrium system has been established. The elements distribution behavior is calculated at the same burden composition and operation parameters as the industrial production. The results show that the absolute errors of the mass fraction (wt%) of Cu, Fe, S, Pb, Zn, As, Sb, Bi in crude copper are 0.06, 0.0030, 0.070, 0.38, 0.39, 0.020, 0.017, 0.034, 0.010, respectively, and the absolute errors of the mass fraction (wt%) of Cu, Fe, S, Pb, Zn, As, Sb, Bi in slag are 0.53, 0.81, 0.020, 0.23, 2.5, 0.0048, 0.0010, 0.0030, 1.49, respectively. The calculated results agree well with the actual industrial production data, indicating that the model can be well applied in the oxygen bottom-blowing continuous converting practice.

By I-H. Jung, J. Kim, B. Konar

"The usage of FeNdB permanent magnet, containing Rare earth elements (REEs), is steeply increasing with its demand for wind-turbine and electrical vehicle. The improvement and recycling of the permanent magnet require good understanding of chemistry of all constituent elements. In order to understand the chemical interactions between REEs and Fe, all Fe-RE binary systems have been critically assessed and optimized based on reliable literature data. The Modified Quasichemical Model and Compound energy formalism is employed to model the liquid phase and the solid solutions present in the binary systems respectively. The enthalpy of the liquid and the intermetallic phases showed a systematic trend along the lanthanide series. This helped to mitigate the discrepancies in literature data and also to predict the binary interactions between some less well investigated Fe-RE binary systems. INTRODUCTIONRare Earth elements (REEs) are a group of seventeen elements (including Scandium, Yttrium and the lanthanide series) that exhibit same characteristic chemical and physical properties. These properties make them valuable to the electronic, appliance, green technology, weapon and medical device manufacturing industries. Compounds of REE with other metals (like Co, Fe, Ni etc.) have unique properties of luminescence, thermal and electrical conductivity, magnetism and ability to act as catalysts and polishing compounds (Gschneidner ,2011).They are not only indispensable for some electronic gadgets of today, like computers, music systems, mobile devices, televisions and MRI machines, but also holds a key to more greener technology of the future. They contribute to the development of more efficient and environment friendly version of everyday products such as cars and light bulbs. REE compounds revolutionized the magnet industry by making them smaller and more powerful with increased longevity, and high temperature workability, which are used in motors and generators that power electronics, telecommunications, electric automobiles and turbines(Humphries, 2011)."

Jan 1, 2012

By Omid Marzoughi

Chromium has a wide range of applications, including as an alloy addition in various steels and also as a corrosion resistance coating. Carbothermal reduction of chromite ore (FeCr2O4) in a submerged arc furnace is an important industrial process for extracting chromium, but the energy consumption is excessive. It is suggested that one area for future research is the low temperature carbothermic solid state reduction of chromite to produce an intermediate product, which can subsequently be upgraded to ferrochromium. In this regard, a thermodynamic model has been developed to investigate this process and the effects of temperature, carbon additions and ore composition on the recovery of chromium and the grade of the ferrochromium, have been studied. Further development of the model may allow it to be applied to the simulation of other processes for the recovery of chromium from chromite ores.

By M. Bugdayci, Onuralp Yucel, K. C. Tasyurek

This paper is a contribution to the theory and quantitative understanding of the processes for the production of magnesium, calcium and strontium metals by metallothermic process. In the present study, effect of reductant type was investigated. Thermodynamic simulation of system was made by Fact Sage 6.4 program. In order to produce magnesium metal, effects of reductants “FeSi, Al, Si and CaC2” were investigated. To understand Calcium-oxide reduction system, effects of Al and CaF2 addition were investigated for different temperatures. In the last simulations, SrO reduction parameters were simulated. Al used as main reductant and BaO, CaO, CaC2 were added to green mixture as a functional additive. Finally probable phases and minimum reduction temperatures are determined.

Mar 1, 2018

By M K. Nahian, R G. Reddy

The thermodynamic model for species distribution in aluminium chloride (AlCl3) and 1-butyl-3- methylimidazolium chloride (BMIC) system was developed. The experimental thermodynamic data, considering a range of aluminium chloride species, such as AlCl4-, Al2Cl7-, Al3Cl10-, Al4Cl13-, and Al2Cl6 were used in developing the model. When the XAlCl3 was in the range of 0 to 0.50, only anion species Cl- and AlCl4- were existing in the solution. As the XAlCl3 value increased more than 0.50, the available anions were Al2Cl7-, Al3Cl10-, Al4Cl13-, and Al2Cl6. Specifically, the concentration of Al2Cl7- increased in the composition range from 0.50 to 0.67 XAlCl3, after which it decreased. This change in the concentration of Al2Cl7- was due to its reaction with excess AlCl3, leading to the formation of Al3Cl10-. The average cathode current density was determined by the electrochemical experiments varying XAlCl3 from 0.50 to 0.71 in the AlCl3:BMIC solutions. The average cathode current density increased as the XAlCl3 increased from 0.50 to 0.67. However, it decreased when the XAlCl3 > 0.67. This trend can be attributed to the electroactive species Al2Cl7-. The Al2Cl7- promotes the reduction rate at the cathode, resulting in an increase in the average cathode current density.

Aug 21, 2024

By Y B. Kang, Y J. Park

Ti-added ultra-low carbon (ULC) steel is produced by adding Al and Ti during the secondary refining process to deoxidise molten steel and to bind C and N which are detrimental to the deep drawing quality of the steel product. However, the production of Ti-added ULC steel faces challenges, including submerged entry nozzle clogging and surface defects on cold rolled coils. The troubles were often attributed to ‘Al-Ti complex inclusions’ in the molten steel. However, the evolution of oxide inclusions including their stability has been still unclear. In the present study, the evolution of these inclusions in Ti-added ULC steel was investigated by phase diagram measurement, CALPHAD thermodynamic modelling, high-temperature stability test for the oxides, and observation of transient behaviour of oxide inclusions in the steel. The phase diagram of the Al-Ti-O system was elucidated with an emphasis on oxygen potential, which significantly controls the stability of the oxides. CALPHAD thermodynamic models and a self-consistent database were developed. The transient behaviour of Al-Ti complex inclusions in Ti-added ULC steel was observed in situ using a confocal scanning laser microscope. This was additionally validated by the new thermodynamic model. The equilibrium phases of the oxide inclusions were investigated using a high-temperature resistance furnace, and were analysed using a secondary electron microscope, energy dispersive spectrometer, and electron back-scattered diffraction. By considering the morphology and crystal structure of these inclusions, the evolution of Al-Ti oxide inclusions was elucidated. Various behaviour of Al-Ti inclusions and their influence on steel cleanliness are discussed.

Aug 21, 2024

By Q. Liu, P. Katsabanis, J. A. Meech

A thermohydrodynamic computer code has been used to simulate dust explosions. For sulphide dusts, the thermodynamic predictions are used to investigate the effect of dust concentration, mineral content and inert materials as well as the quantity of sulphur dioxide produced. It was found that the amount of oxygen available for the explosion is very important and that the dust concentration which gives maximum explosion pressures is obtained at zero or slightly negative oxygen balance values. The sulphide minerals were found to have the following explosibility sequence: pyrrhotite, pyrite, chalcopyrite, sphalerite, covellite, chalcocite and galena, which is in agreement with mine experience. The results show that theoretical calculations can be used to predict explosion pressures and toxic gases produced by a dust explosion and therefore they can assist in the design of protective measures .

May 11, 1988

By L. B. Pankratz

Thermodynamic data on carbides, nitrides, and other selected substances were reviewed, evaluated, and compiled at the U.S. Bureau of Mines Albany Research Center. Values for Cp°, S°, H° - H°298, -(G° - H298)/T, ?Hf, ?Gf, and log Kf are given in tabular form. Cp°, H° - H°248, ?Hf°, and ?Gf° are also expressed algebraically.

Jan 1, 1994

By P. T. Velu

Solubility of metal oxides in the molten salt electrblytes is an important parameter in the electrochemical processing of metals and alloys. The efficiency of an electrochemical process primarily depends on the quantity of metal oxide present in the electrolyte in the dissolved form and its thermodynamic properties. The activity of CeO2 was calculated using the free energy of fusion of CeO2,{ AG°m, CeO2. The AGOm,CeO2 }was deduced from the values of enthalpy, heat of fusion and melting point of Ce02. The activity coefficients of CeO2 as a function of temperature and melt composition were calculated. The thermodynamic data such as integral molar enthalpy, entropy and Gibbs energy of formation were calculated as a function of composition and temperature.

Jan 1, 1994

By Jianxun Song, Hongmin Zhu, Qiuyu Wang, Jungang Hou, Shuqiang Jiao, Xiaobo Zhu

This work presents the results of a study on the Ti3+/Ti2+ couple redox potentials vs. Cl–/Cl2 at the temperature range (673 to 1073 K) in fused LiCl-KCl eutectic by direct potentiometric method. Initial concentrations of TiClx in solvents did not exceed 5.0 mol%. Basic thermodynamic properties of the reactions TiCl2+1/2Cl2(g)=TiCl3 were calculated using the temperature dependencies of apparent standard potentials of the couples E* Ti3+ /Ti2+.

Jan 1, 2014

By L. B. Pankratz

Thermodynamic data on the halides were reviewed, evaluated, and compiled at the Bureau of Mines Albany Research Center. Values for Cp°, S°, H-H°298, -(G°-H°298)/T, ?Hf°, ?Gf°, and log Kf are given in tabular form. CP°, H-H°298, ?Hf°, and AGf° are also expressed algebraically.

Jan 1, 1984