The distribution behaviour of various elements between liquid copper, matte and slag was discussed thermodynamically combining with the experimental results obtained recently. The behaviour of impurities differs greatly depending on the compositions of equilibrating liquid phases and oxygen potential, and the various copper smelting systems were classified in 6 cases for discussion. In accordance with thermodynamic predictions, increasing oxygen potential results in increasing distribution fractions in slag phase for various elements, but any appreciable influence did not be observed in the distribution ratios between copper metal and matte. Under the coexistence of liquid copper phase, substantial fractions of detrimental impurities are distributed in copper phase. Distribution ratios between matte and slag are also influenced by the coexistence of liquid copper or γ-iron phase, especially for arsenic distribution. Because of the differences in thermodynamic characters, the distribution relations for calcium ferrite slag system seem to be different considerably
