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The rate of Sb elimination from molten copper by the use of Na 2 CO 3 slag was measured at 1523 K. The results obtained under the present experimental conditions show that Sb in molten copper is eliminated in a tri-valent or a penta-valent form, depending on the oxygen concentration at the slag-metal interface, and its elimination rate increases with increasing initial oxygen concentration in molten copper. The overall elimination rate of Sb is affected by the stirring condition of the molten copper, which indicates a rate control by mass transfer in that phase. The mass-transfer coefficients of Sb and oxygen in molten copper at 1523 K without external stirring were determined, respectively, to be based on the mass balances of Sb and oxygen in the molten copper and slag phases and the equilibrium relation of the Sb elimination reaction at the slag-metal interface. k m,Sb ϭ 4.0 (Ϯ0.9) ϫ 10 Ϫ5 m # s Ϫ1 and k m,O ϭ 1.3 (Ϯ0.3) ϫ 10 Ϫ4 m # s Ϫ1

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