Antimony activities in copper mattes
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I.
INTRODUCTION
THEactivity coefficients of minor elements at infinite dilution in copper and in copper mattes are a necessary and important basic property that is required to analyze the behavior of trace elements during the copper converting process. In relation to this, we have recently completed our studies on the arsenic activities in copper mattes of the Cu-S-As ternary system. ~The present communication concerns the antimony activities in copper mattes. Antimony activities in copper mattes have been reported by Roine and Jalkanen. 2 However, data are not available for copper saturated mattes of the Cu-S-Sb ternary system. Antimony activities in molten copper have been measured by Bode and co-workers 3 and Itoh and Azakami. 4 Unfortunately, good agreement does not exist amongst these studies on the activity coefficients of antimony at infinite dilution. Bode et al. did not take into consideration the equilibrium between the various gaseous species of antimony nor the contribution of the vapor pressure of copper in their studies. Itoh and Azakami considered the gaseous species of antimony; however, their investigations were restricted to compositions in excess of 10 at. pct antimony. In the present investigation, the following systems were studied by a mass spectrometric Knudsen effusion technique: (a) antimony activities in molten copper at 1373 K and (b) antimony and copper activities in the two-melt composition range of the Cu-S-Sb ternary system at 1423 K. II.
EXPERIMENTAL
The apparatus and experimental procedures have been described in detail previously; I thus only a brief outline follows. Samples of Cu-Sb and Cu-S-Sb alloys were prepared by mixing the required amounts of 99.99 pct copper, 99 pct sulfur, and 99.99 pct antimony. The mixtures were vacuum sealed in quartz ampoules and held at 1423 K for 3 hours. The molten samples were then air quenched. In the case of the Cu-S-Sb system, the selected compositions resided in M. HINO, formerly Visiting Scientist at the University of Toronto, is Lecturer, Tohoku University, Sendai, Japan. J.M. TOGURI is Professor, Department of Metallurgy and Materials Science, University of Toronto, Toronto, ON M5S 1A4, Canada. Manuscript submitted April 23, 1986. METALLURGICALTRANSACTIONS B
the two phase region such that a copper-rich phase and a sulfide-rich phase were formed. The activities were determined by use of the previously described mass spectrometer-Knudsen cell assembly. The ratio of the antimony and copper intensities in the respective unknown and reference samples of defined activities were measured. Ten measurements were made for each intensity. The mass spectrometer was operated at 12 eV. Equation [1] was used to determine the antimony and copper activities. log ai(u) = log (li+(u)] + log ai(r)
\Ii+ (r)/I
[1]
i is the gas species under consideration and (u) and (r) are the unknown and reference samples, respectively. In all cases the Cu-Sb binary alloys were used as the reference sample and the antimony activities reported by Itoh and Azakami 4 were
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