2005 Volume 46 Issue 10 Pages 2180-2189
The rate of As elimination from molten copper by the use of Na2CO3 slag was measured at 1523 K. The results obtained, under the experimental conditions of this study, show that As in molten copper is eliminated in a pentavalent form and that its elimination rate increases with increasing initial oxygen concentration in molten copper. Based on the results obtained in the present study, the overall rate of As elimination is probably controlled by mass transfer in molten copper. The mass-transfer coefficient of As in molten copper at 1523 K was determined to be 1.3(±0.4)×10−4 m·s−1 based on the material balances of As and oxygen in the molten copper and slag phases, and the equilibrium relationship of the As elimination reaction at the slag-metal interface. In addition, the behavior of the simultaneous elimination of As and Sb, which coexist as impurities in molten copper at 1523 K, were also investigated from a kinetic viewpoint. The results show that the elimination rate of As is much higher than that of Sb, and two types of elimination behaviors are observed depending on the initial oxygen concentration in molten copper. At relatively low initial oxygen concentrations, As is preferentially eliminated with an initial plateauing of Sb elimination. On the other hand, both elements are eliminated simultaneously at relatively high initial oxygen concentrations. These behaviors were examined from the viewpoint of the oxygen concentration at the slag-metal interface.