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Sohn International Symposium on Advanced Processing of Metals and Materials, San Diego, California, August 27-31 2006 Liquidus Relations of Calcium Ferrite Slags in Continuous Copper Converting, (Plenary Lecture)
Ian McBow¹ ; Akira Yazawa ² ; S. Llubani ¹; Robert Budd³ ; Florian Kongoli ¹; late Yoichi Takeda⁴ ; Katsunori Yamaguchi⁴ ;
¹FLOGEN Technologies Inc,1255 Laird Blvd., Ste.388, Mont-Royal, Quebec, Canada
²Tohoku University, 16-32, Niizaka, Aoba-ku, Sendai, 981-0934 JAPAN
³FLOGEN Technologies Inc 3422 Old Capitol Trail, #791, Wilmington, DE, USA 19808
⁴Faculty of Engineering, Iwate University, Morioka, Japan.

ABSTRACT

Calcium ferrite slags have been used in continuous copper converting for the last 30 years. However some basic data on these slags were not yet complete especially on the liquidus relations which have been limited to simple three component slags. In the present paper, the existing experimental data on the phase diagram of Cu2O-FeOx-CaO system of late Prof. Takeda are first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of calcium ferrite slag. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO vs. SiO2 and of Fe/CaO vs Temperature are proven to be much more convenient for ferrite slags. Based on these diagrams the effect of SiO2 on the melting temperature is quantified. The effect of Cu2O on liquidus of calcium ferrite slags is also quantified through the model. Some Fe/CaO vs. Cu2O diagrams are predicted and the results show good agreement with the experimental data on the Cu2O-FeOx-CaO system. It is also shown that in the presence of liquid copper, Cu2O is dissolved in slag depending on the oxidation degree of the system and might lower the liquidus temperature. The model shows that the optimum Fe/CaO ratio of calcium ferrite slags shifts delicately depending on the minor components. Some discussions are also presented taking into account the plant observation of continuous converting.

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