5 - Phase Equilibria in Ferrous Calcium Silicate Slags:...

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Phase Equilibria in Ferrous Calcium Silicate Slags: Part II. Evaluation of Experimental Data and Computer Thermodynamic Models STANKO NIKOLIC, HECTOR HENAO, PETER C. HAYES, and EVGUENI JAK Ferrous calcium silicate slags (described by the FeO-Fe 2 O 3 -CaO-SiO 2 system) are the basis for a number of slag systems used in nonferrous smelting. Characterization of this slag system is necessary to improve the design and optimization parameters of new processes, including fluxing and operating temperatures. Particularly of interest are the phase relations at interme- diate oxygen partial pressures relevant to processes such as copper converting. Experimental data on the phase equilibria of these slags at controlled oxygen partial pressures in the tem- perature range between 1200 ° C and 1350 ° C are discussed, di±erences between various data sources are analyzed, and discrepancies are resolved. An evaluation of two thermodynamic computer models is undertaken to verify the computer-aided predictions using the experimental data. New experimental data for this system are reported for the temperature condition of 1300 ° C, de²ned using the equilibration/rapid-quenching/electron probe microanalysis (EPMA) with wavelength dispersive detectors technique. This new information, combined with results from the previous study, has enabled the equilibrium liquidus compositions to be de²ned over a wide range of temperatures and oxygen partial pressures. DOI: 10.1007/s11663-008-9131-0 Ó The Minerals, Metals & Materials Society and ASM International 2008 I. INTRODUCTION T HIS article is the second of a series of articles investigating phase equilibria in ferrous calcium silicate slags described by the FeO-Fe 2 O 3 -CaO-SiO 2 system, at intermediate oxygen partial pressures. In the ²rst arti- cle, [ 1 ] the results of experiments equilibrated at 1200 ° Cto 1350 ° Cat50 ° C intervals were presented at the oxygen partial pressures of 10 - 5 and 10 - 6 atm. Experimental work has been conducted on this slag system at similar oxygen partial pressures and temperatures by Henao et al. [ 2 ] and Kimura et al. [ 3 ] The experimental work of Henao et al. at 1300 ° C, 1350 ° C, and 1400 ° C investi- gated the slag system in the oxygen partial pressure range of 10 - 3.4 to 10 - 9 atm, with detailed results for the spinel isotherm at 10 - 6 atm. The experimental work of Kimura et al. , [ 3 ] which encompasses the previous work published by Tsukihashi, [ 4 ] investigated the slag system at a temperature of 1300 ° C and an oxygen partial pressure of 10 - 7.75 ,10 - 5.75 , and 10 - 2.7 atm. The work of Kimura et al. [ 3 ] and other authors [ 5 ] on the ferrous calcium silicate system at intermediate oxygen partial pressures did not investigate the slag at the speci²c oxygen partial pressure of 10 - 6 atm; therefore, direct experimental comparison can only be undertaken with the results of this work [ 1 ] and that of Henao et al.
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This note was uploaded on 05/13/2011 for the course METALLURGY 1107 taught by Professor Hegurange during the Three '10 term at Murdoch.

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5 - Phase Equilibria in Ferrous Calcium Silicate Slags:...

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