The mechanism for the removal of the group Vb elements, As, Sb, Bi, from molten copper using a Na2C03 flux has been investigated in order to develop a pyrometallurgical copper refining process. Experiments were carried out in an argon atmosphere using 300g of molten copper containing various amounts of the group Vb elements and oxygen. The temperature range of this study was 1150-1250°C. The arsenic content in copper decreased rapidly from about 2500 to 200 ppm within 10 min of adding the Na2C03 flux (5% of the weight of the molten copper). Antimony behaved in the same manner as arsenic except that under the same experimental conditions, the time required for elimination was longer. However, the Na2C03 flux had little effect on the removal of Bi from the copper. While the effect of temperature was found to have only a little influence, the oxygen content in copper had a large effect on the arsenic and antimony elimination reaction. The removal rate increased with increasing oxygen contents in copper. The mechanism for the removal of these elements are discussed based on the observed evolution of CO2 and on X-ray radiographic data. The removal of arsenic and antimony can be accounted for by the equation 2(As or + 5Q+ Na2C03 = 2Na (As or Sb) 03 + CO2 (1) where Krepresents the element X dissolved in molten copper.
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