Arsenic activities in molten copper and copper sulfide melts
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I.
INTRODUCTION
A
small amount of arsenic is generally associated with copper sulfide ores and as in the case of other impurities, arsenic is eliminated during the various stages of smelting and refining. In recent years the availability of high grade sulfide ores has diminished and thus the treatment of low grade and complex sulfide ores has become important. Unfortunately, these ores generally contain larger amounts of the group Va elements such as arsenic, antimony, and bismuth which can lead to removal problems during the smelting process. It is essential to eliminate these impurities since they have a deleterious effect on the mechanical and electrical properties of copper. An understanding of the behavior of impurities such as arsenic in the copper smelting process requires knowledge of the thermodynamic properties of arsenic in copper and in copper mattes. The arsenic activities in molten copper have been reported by Azakami and Yazawa, 1 Jones and Philipp, 2 Jeffes and co-workers, 3 and Hino. 4 However, the activity coefficient of arsenic at infinite dilution in molten copper, which is one of the most important thermodynamic properties, can not be determined directly from these experimental data because they were not obtained at sufficiently low arsenic content. Bode et al. 5 have measured the arsenic activity in dilute solution and obtained a value of 1.0 x 10 -6 for y~. Hino 4 estimated 1.0 x 10-2 for 3'~ in the Cu-As binary system at 1423 K. This was based on the activity of copper 1 combined with the arsenic activity in the high arsenic composition range and the Gibbs-Duhem integration. Dabbs and Lynch6 have evaluated Y~s at 1273 and 1373 K by recalculating the data reported by Azakami and Yazawa ~ and Jeffes et al. 3 Arsenic activities in copper mattes have been reported by Lau et al. ,v Itagaki et al. ,8 Hino,4 and Roine and Jalkanen. 9 However, the arsenic activity in Cu2S mattes equilibrated with copper is not available. The arsenic activities in both phases of copper and white metal which are in equilibrium with each other are necessary for the analysis of the arsenic behavior during the copper M. HINO, formerly with the Department of Metallurgy and Materials Science, University of Toronto, Toronto, ON, Canada, is Lecturer, Department of Metallurgy, Tohoku University, Sendai, Japan. J. M. TOGURI is Professor, Department of Metallurgy and Materials Science, University of Toronto, Toronto, ON, Canada, M5S 1A4. Manuscript submitted December 3. 1985. METALLURGICALTRANSACTIONSB
converting process. Thus, in this study, the arsenic activities in molten Cu-As binary alloys and in the copper-rich phase as well as in the CuzS phase of the Cu-S-As ternary system were measured at 1423 K.
II.
EXPERIMENTAL
A. Experimental Method
The present studies were performed by using a double Knudsen cell arrangement coupled to a quadrupole mass spectrometer. ~0With this system the arsenic activities were determined by use of the ratio of intensities of the arsenic vapor between samples in which the arsenic activiti
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