Phase equilibrium and thermodynamic properties of SiO₂-CaO- FeO_x slags for copper smelting - Research achievements of professor Yoichi Takeda

Although the iron silicate slags are being widely used in extractive metallurgy, they represent some inherent inconveniences such as the loss of valuable metals and the low holding capacity for iron oxides, especially, for magnetite. In this respect, the SiO₂-CaO-FeO_x slags have attracted the attention as new slag systems. The late Professor Yoichi Takeda had investigated the phase relations and thermodynamic properties of the SiO₂-CaO-FeO_x slag systems, and his great achievements in the following studies are reviewed: (1) determination of phase relations and oxygen potential in the CaO-FeO_x based slag systems, (2) activity coefficients of the slag components, (3) distribution ratio of some minor elements between the slag and copper phases in relation to the oxygen potential and (4) sulfide and oxide solubility of copper in the slags in relation to the matte grade. These results have provided very important information for use of the SiO₂-CaO-FeO_x slags in copper smelting and non-ferrous metallurgical processes, e.g. he had suggested the availability of these slags for smelting high-grade copper mattes.