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By S M. J Koleini, F Hedjazi

The purpose of this research was to study the calcination of lead-zinc flotation tailings from the Angouran lead and zinc flotation plant in Iran as a pre-concentration step prior to hydrometallurgical processing of the oxidised tailings. There is an abundance of these tailings in the Angouran region and making use of these tailings would help preserve national wealth and also reduce the serious problems of environmental pollution caused by the tailings. At the optimal conditions of calcining at 750 - 800¦C for 45 minutes, the sample showed a mass loss of about 19 per cent. Mineralogical analyses showed that under these conditions the carbonate minerals including smithsonite (ZnCO3), calcite (CaCO3) and dolomite (Ca Mg (CO3)2) decomposed to their respective oxides. Hemimorphite (Zn4Si2O7 (OH)2.H2O) converted into willemite (Zn2SiO4) and this transformation postponed the formation of silica gel in the leach solution. The grade of zinc increased from 22.20 per cent to 29 per cent. These mineralogical changes resulted in desirable reactions in the acid leach process.

Jan 1, 2004

The published liquidus data on the Pb-PbS system have been correlated on the basis of one-coefficient Margules equations. Thermodynamic properties of the components of this system have been obtained, and it has also been found that the calculated miscibility gap of this system exists over a very narrow range of temperature (1041 to 1058°C).

Jan 1, 1972

By T Iwadachi, T Fujisawa an, G R. Alvear

A large amount of Be2C and BeO is formed during the Cu-Be alloy production process, because beryllium is a highly reactive element. Carbide and oxide formation impairs the production yield and the quality of the Cu-Be alloy products, and therefore should be minimised. As a first step for solving these problems in the process, the following thermodynamic properties of the Cu-Be-C-O system were investigated. Based on the results, the equilibrium relations of the Cu-Be-C-O system were clarified and the operational conditions of the current Cu-Be alloy production process were also examined and discussed.

Jan 1, 2000

By Wadsley MW

This paper gives an overall view of the CSIRO-SGTE computer system for thermodynamic calculations. The basis of the system is the coupling of a large self-consistent numeric data bank of thermodynamic information to a modular set of application programs. These seven programs cover management of data files, calculation of thermodynamic properties for species and reactions, plotting of predomin- ance area diagrams, equilibrium and enthalpy balances for complex processes, analysis of thermodynamic efficiency and the estimation of unknown properties. The data bank contains a wide coverage of species and data types so that the system may be applied to many areas of chemistry and metallurgy.

Jan 1, 1984

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

A simulation program has been developed tc predict the airflow distribution and thermal environment in multi-level narrow lode Cornish =n mines. Because of the approximate equality between fan power and natural ventilation _rergy a true thermodynamic mesh balance using mass flow rather than volume flow rate was required. Compressibility is allowed for by calculating mesh corrections on a mass flow of dry air basis. In this context, and within the confines of any steady state model, both the steady flow energy and pressure equations are satisfied with equal validity. The mesh balance includes natural ventilation energy, frictional losses, moisture lift work, water droplet energy and fan energy.

Jan 1, 1988

By Merritt RR

The equilibrium phase relations in the Fe- Mn-Ti-0-S system were established at 1380 and 1485 K. The elemental distributions between the equilibrium phases were obtained by chemical- ly analysing selected samples from the phase study. The results are considered in relation to the coal reduction process for upgrading ilmenite. The beneficial effect of adding sulfur to a kiln that uses a manganese-rich feed is ex- plained by the formation of a metal-sulfide solid-solution phase that removes part of the manganese from the oxide system. The optimum conditions for operating the reduction kiln are determined, and the practical need to operate the kiln at other than optimum conditions is explained. It is shown how the experimental data can be used to predict the best compromise conditions for reduction and the resultant purity of the product.

Jan 1, 1980

Activity-composition-temperature relations for both gold and nickel have been determined for the solid and liquid states of the gold-nickel system by the application of the Margules equations. These relations are in satisfactory agreement with activity measurements of nickel in the solid state, the observed phase boundaries of the system between 700 and 1725°K, as well as being consistent with data on the enthalpy of mixing.

Jan 1, 1971

Equilibrium in the reaction H2(g) + [%0] (in liquid copper) = H2O (g) was investigated at temperatures between 1200 -and 1350°C with p(H2Oj/p(H2) ratios between 1 to 15. A semi-microbalance was used for direct measurement of dissolved oxygen in molten copper. Oxygen was found to obey Henry's law under the experimental conditions used. The standard free-energy change for the above reaction is given by Equation 1where 1 weight per cent solution is the standard state for dissolved oxygen.For the dissolution of oxygen in copper according to 1/2 O2(g) = [%0] (liq. Cu), the standard free energychange is given byEquation 2.

Jan 1, 1973

By Yamada K, Abe H

Magnetic scanning type mass spectrometers have been given improved sensitivity with a large dynamic range and considerable resolution by the addition of a computer-controlled electric equipment. A mass spectrometer equipped with this newly developed electric system was applied to studies of the activities of liquid iron-silicon alloys and of liquid iron-phosphorus alloys at 1600¦C. The range of silicon concentration was 5.8at%-51.1 Si= at%, and values of ySi -3.1+0.15 and es 11.5 +1.5 were obtained. The concentration range of phosphorus was 1.3at%-5.7at% and a value of eP=7.3+0.1 was obtained.

Jan 1, 1980

By Agrawal R. D, Kapoor M. L

Activity of FeO in the ternary system MgO-FeO-CaO in contact with metallic iron has been measured at 1000 K employing the cell.PtIFe, (Mg, Fe, Ca)OIZr02 - CaOIFe, FeOlPt. Measured data are used to study the phase stability relations in the system MgO-FeO-CaO and an isothermal section at 1000 K through this system is drawn.

Jan 1, 1987

By Kapoor M. L

Emf measurements on SE galvanic cell: SS; Ni-NiO I solid electrolyte/ZrO2 + CaO I [Pb + Bi]liq alloy; (PbO); SS were made in the temperature range 913-1034 K to determine the thermodynamic properties of oxygen dissolution in liquid lead. Bismuth alloys with bismuth in the dilute concentration range of 0 to 3.08 mass per cent and oxygen in the alloy varied by equilibrating the metallic system with a suitable (PbO) slag. Wagner's interaction parameter approach was used to calculate the ternary interaction parameter, eBiO at temperatures of 913, 953 and 993 and 1034 K and to observe the temperature dependence eBiO = 19 200/T - 17.454. Quasichemical fonnulation was employed to yield lnf BiO and reveal the effect of bismuth on oxygen in lead. The results obtained are discussed on the basis of theoretical models and the value of Wagner's energy parameter 'h' estimated to predict the results in a Pb-Bi-O system.

Jan 1, 1995

By M Hino, D R. Swinbourne

The thermodynamic properties of arsenic in metal, speiss, matte, slag and gas phases are first summarised in this paper. Arsenic associates with sulphide minerals and generally has compounds of high volatility, but it has a weak affinity for sulphur and a strong affinity for metals, especially copper and iron. In the initial stage of the oxidation of sulphide concentrates arsenic is volatilised easily prior to the oxidation of FeS, although it tends to be fixed in the condensed phase as FeAsO4 if the concentrate is over-oxidised. Thermodynamic simulation of oxidative copper smelting reveals the distribution of arsenic between matte, slag and gas, and the possibility of condensation of arsenic from the resulting waste gas is discussed. In reductive smelting more arsenic remains in the metal or matte, and is sometimes concentrated as a separate speiss phase. The phase relations and thermodynamic properties of speiss are also summarised briefly. Arsenic refining from smelted copper metal is shown, from an examination of the basic principles of arsenic removal into slags, to be difficult. Owing to its weak affinity for lead however, arsenic refining from lead bullion is seen to be much easier.

Jan 1, 2000

By S Jahanshahi, D R. Swinbourne

The classical metal-slag-gas equilibrium technique was used to study the thermodynamic activity of cobalt, iron and their oxides in iron silicate based slags containing under controlled oxygen potential (3.70 x 10-8 to 2.95 x 10-7 atm) at 1573 K. The measured activity of cobalt oxide in FeOx-25 wt per cent SiO2 slags showed positive deviation from ideal behaviour for melts with up to ten wt per cent CoO. At higher silica contents, the behaviour became closer to ideal and in accord with previous studies on silica saturated slags. The activity coefficient of FeO in these slags had virtually no dependence on the CoO content. Partial substitution of silica by lime resulted in an increase of the activities and activity coefficients of CoO, FeO, Fe2O3 and Fe3O4. The results indicate that saturation of the slag with a magnetite phase occurs at CaO contents of five wt per cent and higher. Phase equilibria studies SiO2-FeO-Fe2O3-CaO slags containing cobalt were also carried out using the drop-quench technique. Results from these experiments confirmed the formation of a magnetite solid solution containing about three wt per cent CoO at lime contents of five wt per cent and higher at 1573 K and 2.9 x 10-7 atm of oxygen.

Jan 1, 2000

By J Rapkoch, M Cerna

As long as the tendency of Chilean copper ores continues to feature high levels of impurities, the smelters will tend to produce high-impurity mattes. The most notable impurities include As, Sb, Pb and Zn. Producing high-quality copper with such materials is a major challenge to metallurgical engineers and operators. More investigations into process optimisations and/or alternatives are needed, using both theoretical knowledge and operational skill. Converting of matte in Chile depends on the matte grade using established technologies. Mattes up to 66 per cent Cu, such as those from Outokumpu Flash furnaces, are converted in two stages, while typical Teniente Converter mattes, ranging from 70 - 74 per cent Cu are converted in one blow, directly to copper. In this paper thermodynamic data are used to evaluate possible variations in the use of traditional technologies applied to smelt copper concentrates with high impurity levels. The results of this analysis help to predict the impurity distributions between matte-slag-gas during the slag blow, and between copper-slag-gas during the copper blow. For converting high-impurity white metal, the effectiveness of volatilisation in the slag blow is analysed. In the copper blow, the type and the amount of flux (SiO2, CaO and others) are altered with the aim of optimising impurity distribution to the slag and gas.

Jan 1, 2005

By Hikosaka A, Chiba A

In a fundamental study of the physical chemistry of steelmaking slag, equilibra bet- ween hydrogen-water vapour gas mixtures and liquid slags contained in solid iron crucibles have been measured for four binary slags, FetO-CaO, FetO-Si02, FetO-TiO2 and FetO-Al203 at 14000C. From the data, the activity of iron oxide and the ratio of ferrous and ferric ions (A = Fe3+/Fe2+) were calculated for the slag composition. The best ionic model is found to be that based on regular solution of cations. The oxygen distribution between slag and metal is quantitatively expressed by this model over a wide range of slag composition.

Jan 1, 1980

By Iwu GO, Almond DP, Joasoo _

The gravimetric integral Knudsen effusion method was used to measure cadmium activity values in binary liquid In-Cd alloys in the range 523 to 573 K. The activity measurements together with other studies from the literature indicate that special bonding conditions exist in the melts near a composition corresponding to InCd3. Sound velocities in In-Cd melts were also measured using a precision pulse-echo over- lap method in the range 404 to 953 K. The frac- tional deviation of experimental and ideal isentropic compressibilities at 623K shows a functional dependence on composition with a pronounced maximum near the composition 75 at.%.

Jan 1, 1980

By Toguri JM

A solid electrolyte technique has been used to measure the activity of cobalt in liquid cobalt-gold alloys containing between 0.085 and 0.50 mole fraction of cobalt, and for temperatures from just above the liquidus to around 1550 K. The system exhibits positive deviation from ideality, both in the activities of cobalt and gold, and in the enthalpy and excess entropy of mixing. The results agree with previous measurements using a Knudsen cell - mass spectrometer technique, but differ from those reported for a gas equilibration method. The data have been used to calculate the activity coefficient of cobalt oxide in silica saturated iron silicate slags and to express the solubility of cobalt in such slags as a function of cobalt activity and oxygen pressure.

Jan 1, 1984

Thermodynamic properties of the solutions of hydrogen in metals and carbon in austenite were investigated and it is possible to predict the interstitial solubility in these systems over relatively wide ranges of temperature and solute activity. Monte Carlo methods were used to compute the arrangements of interstitial atoms on the tetrahedral sites in body centred cubic metals and the octahedral sites in face centred cubic metals. It was shown that the non-configurational entropies of solution of hydrogen in metals can be interpreted as being principally vibrational and on this basis the potential value of the isotopic solubility ratio theory in indicating the compositional variation of these non-configurational entropies was discussed. The need for future work along these lines is pointed out.

Jan 1, 1970