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

Abstract

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

Mechanisms of Oxidation and Vaporization of Antimony from Liquid Copper with CuCl–CaO Fluxes

“…Moreover, it was also confirmed that a part of antimony vaporized from flux to gas phase according to the mass balance. Compared with the reported Na 2 CO 3 and Cu 2 O-based fluxes, 12,13) the CuCl-CaO fluxes have a high removal efficiency for Sb from liquid copper. For the CuCl-CaO fluxes, the oxidation reaction of Sb in liquid copper may proceed the removal of antimony from liquid copper because the chlorination reaction of antimony by CuCl is difficult at 1 423 K. The source of oxygen for the oxidation reaction of 3 and SbOCl in flux were observed in the fluxes, and these chloride and oxychloride vaporized to gas phase.…”

“…15) From the thermodynamic viewpoint, it can be confirmed that the Cu 2 O in flux decomposes into oxygen and copper at 1 423 K as shown in Eqs. (11) and (12). Therefore, in this study the source of oxygen to oxidize Sb in copper may come from the dissolution of Cu 2 O existing in CuCl-CaO flux to molten copper.…”

Removal of Antimony from Liquid Copper by Using CuCl–Na2CO3 Fluxes at 1423 K

“…Tanahashi et al 16) reported that the concentration of Sb in liquid Cu-0.155mass%Sb alloy decreased with time by using Na 2 CO 3 flux at 1 523 K, and reached 0.001 mass% at 240 min. A part of their experimental results are also shown in Fig.…”

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

“…19) An alumina crucible, with an inside diameter of 35 mm and a height of 150 mm, was charged with 400 g of a mixture of oxygen-free copper (99.99% pure), appropriate amounts of Cu 2 O powder (98% pure), Cu-As and/or Cu-Sb alloys for the initial composition of the copper phase shown in Table 1. The sample in the crucible was heated to 1523 K. Argon gas was continuously flushed at a flow rate of 3:33 Â 10 À6 Nm 3 Ás À1 over the sample melt to prevent the oxygen dissolution onto the melt from the gas phase.…”

“…The rate of Sb elimination was measured at 1523 K with the Na 2 CO 3 slag placed directly on molten copper, which makes the system simpler than the slag injection process. 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.…”