4 - Phase Equilibria in Ferrous Calcium Silicate Slags Part...

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Phase Equilibria in Ferrous Calcium Silicate Slags: Part IV. Liquidus Temperatures and Solubility of Copper in ‘‘Cu 2 O’’-FeO-Fe 2 O 3 -CaO-SiO 2 Slags at 1250 Ŷ C and 1300 Ŷ C at an Oxygen Partial Pressure of 10 - 6 atm STANKO NIKOLIC, PETER C. HAYES, and EVGUENI JAK Liquidus temperatures and the solubility of copper oxide in slag are evaluated and discussed for the ferrous calcium silicate system (described by the ‘‘Cu 2 O’’-FeO-Fe 2 O 3 -CaO-SiO 2 system). The solubility of copper in this system was interpolated into the fully liquid region by ±tting the experimental values to a second-power polynomial in terms of CaO/SiO 2 and SiO 2 /Fe com- positional parameters. The industrial application of this slag system for copper converting is discussed and optimal slag compositions are de±ned that ensure one stable liquid phase over the range of temperatures at the oxygen partial pressure of 10 - 6 atm. The copper oxide solubilities in iron-silicate, ferrous calcium silicate, and calcium ferrite slags are compared at ±xed condi- tions relevant to copper converting. DOI: 10.1007/s11663-008-9129-7 ȑ The Minerals, Metals & Materials Society and ASM International 2008 I. INTRODUCTION E XPERIMENTAL work has been undertaken at an intermediate oxygen partial pressure of 10 - 6 atm on ferrous calcium silicate slags, described by the ‘‘Cu 2 O’’- FeO-Fe 2 O 3 -CaO-SiO 2 system, both without [ 1 ] and at metallic copper saturation [ 2 ] using the established equil- ibration/rapid quenching/electron probe X-ray micro- analysis (EPMA) technique. [ 3 5 ] This system forms the basis of a number of slag systems used in nonferrous smelting; at copper saturation and intermediate oxygen partial pressures, it is particularly relevant to copper converting. There are a number of issues that need to be investigated for this slag system that are critical to understanding how best to facilitate improvements in the design, development, and optimization of new and existing copper converting processes: (1) the e²ect of copper on the liquidus and solidus of the slag system, (2) the solubility of copper within the liquid slag, (3) comparison and evaluation of existing computer- generated predictions, and (4) the industrial application of the slag. II. RESULTS AND DISCUSSION A. Effect of Copper Saturation on the Liquidus of the ‘‘FeO’’-CaO-SiO 2 System The experimental liquidus compositions in the ‘‘Cu 2 O’’-FeO-Fe 2 O 3 -CaO-SiO 2 system, de±ned in the previous work both without [ 1 ] and at copper satura- tion [ 2 ] at an oxygen partial pressure of 10 - 6 atm, are plotted as projections onto the FeO-CaO-SiO 2 plane in Figures 1 and 2 for the temperatures 1250 Ŷ C and 1300 Ŷ C, respectively. Details of the experimental methods and techniques, including the ±xing of the oxygen partial pressure and the projection and recal- culation of the results at copper saturation, are contained in the referenced articles.
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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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4 - Phase Equilibria in Ferrous Calcium Silicate Slags Part...

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