Arsenic and antimony are not readily removed from crude copper by simple oxidation, as evident in coventional fire refining practice, and from thermodynamic considerations. Removal of various impurites from the liquid crude copper using flux has been studied thermodynamically and experimetally. 1. In the oxidzing atomsphere of oxidzed serlimetals, there exists a great stability for M₂O_5 than fort M₂O₃. 2 In the experiment of heating mixture of CaO-CuO-Sb systems, the compounts of Ca₂Sb₂O_7 were firmed at 1200℃. 3. Calcium choride is especially interesting because arsenic and antiominy have also been elimnated probably in the forms of calcium arsenate and antimonate.