Thermodynamic Considerations for Eliminating Ni and Zn from Molten Copper by Na<SUB>2</SUB>CO<SUB>3</SUB>-Base Slag

The rate of antimony elimination from molten copper by the use of Na2CO3 slag

“…[1,2,3] In particular, Yamauchi and co-workers established a principle for obtaining L X by calculation. By the application of this calculation method, L X values of the impurities X ϭ Sb, [4][5][6][7][8][9] As, [8,10] Sn, [11] Te, [12] Se, [12] Fe, [13,14] Si, [15] P, [15] Zn, [16] Ni, [16] and S [17] were successfully evaluated and reported as functions of temperature, slag composition, oxygen, and CO 2 partial pressures. In addition, it was confirmed that the Sb and As concentrations in copper can be reduced using this slag treatment to 0.1 mass ppm, the level required for high-purity copper.…”

Effects of Coexisting Oxygen and Antimony in Molten Copper on Rate of Arsenic Elimination from the Copper Phase by the Use of Na<SUB>2</SUB>CO<SUB>3</SUB> Slag

“…In order to confirm this, the dissolution of O 2 gas, dissociated by the thermal decomposition reaction of Na 2 CO 3 slag, into oxygen-free copper melt was examined by conducting run B-1. Figure 10 show that the oxygen concentration increases and approaches $200 mass ppm, which is the same level as the final oxygen concentration in run AS-1, as the dissolution reaction of O 2 gas into molten copper progresses by reactions (12) and (13).…”

“…9(a) and 10, it is clarified that for relatively low initial oxygen concentration, As and Sb in molten copper react not only with the oxygen initially dissolved in the molten copper but also with the oxygen generated according to reactions (12) and (13) so that they are transferred into the slag phase as oxides. In other words, it is necessary to raise the oxygen concentration in the molten copper in order not only to enhance the elimination rates of As and Sb but also to prevent the evaporation loss of the Na 2 CO 3 slag.…”

“…Several research groups have therefore been conducting fundamental studies on this slag treatment. Using a thermodynamic approach, Yamauchi and coworkers have investigated the distribution ratios of various impurities between the Na 2 CO 3 slag and the molten copper, L X , {defined as (mass% of X in slag)/[mass% of X in molten copper]}, where the impurity element X ¼ Sb, [1][2][3][4][5][6] As, 5,7) Sn, 8) Fe, 9,10) Te, 11) Se, 11) P, 12) Si, 12) Ni, 13) Zn, 13) S, 14) and have discussed the slag consumption of this refining process using a mathematical model. 15,16) From a kinetic viewpoint, the Sb elimination rate from molten copper by injecting soda ash into molten copper has been measured by Kozlowski et al 17) and Stapurewicz et al 18) However, the kinetic mechanism of impurity elimination during this injection process is too complicated and has not yet been clarified.…”

“…19) In the present study, As was selected as an impurity element, and its elimination rate and mechanism was investigated by a very similar kinetic analytical method as the one described in the previous paper. 19) It should be noted that all the previous studies [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] were conducted for the purpose of elucidating the elimination behavior of single impurity elements from molten copper. However, from the viewpoint of practical operations, multiple impurity elements coexist in crude copper and will simultaneously react with Na 2 CO 3 slag.…”