Thermodynamic properties of molten sulfides: Part III. The system Cu-Ni-S
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is part of a s e r i e s of experimental studies at the Stanley-Thompson Laboratories of the Henry Krumb School of Mines, Columbia University, of systems of molten sulfides of technological importance. Previous publications from these laboratories have dealt with nickel-sulfur 1 and cobalt-sulfur2 melts. We present here the results of determinations on copper-nickel-sulfur melts at nominal temperatures of 1200 and 1400°C. The measurements included equilibrium sulfur pressures in the homogeneous liquid region, and in the miscibility gap. These supplement the limited e a r l y data of Matousek and S a m i s3 at 1200°C, clarifying the activity behavior of this sytem. The miscibility gap boundaries were determined also at 1200 and 140ffC, supplementing the data available at the lower temperatures. The m e a s u r e ments are essentially in agreement with the d e t e r minations of Asano and Ichio4 at 1150 to 1250~C, and of Schlitt e t a l5 at 1200°C. EXPERIMENTAL The same basic equipment as used by M e y e r et alI for nickel-sulfur melts was employed in the present determinations. Details not included in what follows can be found in their publication. The procedure involved equilibration of the melts with gaseous mixtures of hydrogen sulfide and hydrogen. The melts were held in a crucible maintained at temperature in a furnace. The crucible assembly was fitted with a gas inlet tube, a gas outlet tube (also serving to access the melts for sampling purposes) and a thermoeouple well with tip immersed in the melt. Radiation shields served to enlarge the zone of uniform temperature around the crucible, and the use of high gas velocities ensured the avoidance of thermal diffusion effects. %7 Temperature measurements were made with platinum alloy thermocouples. At temperatures of SANG L. LEE, formerly GraduateStudent, Henry Krumb School of Mines, Columbia University, New York, NY, is now Managing Director, DainongCompany, Ltd., Seoul, Korea. JOSE M. LARRAIN and HERBERT H. KELLOGG are Associate Professor and StanleyThompson Profe~or of Chemical Metallurgy, respectively ttenry Krumb School of Mines. Manuscript submitted September 18, 1979. METALLURGICAL TRANSACTIONS B
1200°C a Pt/Pt-10 pet Rh couple was used. Because of t h e i r superior stability Pt-6 pct Rh/Pt-30 pct Rh thermocouples were employed at 1400°C. All thermocouples were periodically calibrated against the freezing point of copper following recommended procedures. The uncertainties in the temperature measurements are believed t o be of the o r d e r of +I°C at 1400°C. A calibrated gas interferometer was used to d e t e r mine gas compositions by reference to t h e i r index of refraction at room temperature. For mixtures of hydrogen sulfide and hydrogen, probably e r r o r s are less than 0.2 pct relative in measurements of gas compositions with more than 2 vol pct H2S, and less than 1 pct relative for compositions below 2 pct H2S. Materials Purified hydrogen (99.95 pct) supplied by Linde Co. was used after passing through a "DEOXO" purifier and drying colum
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