Influence of high-temperature oxidation kinetics of copper on the electrical properties of the melt

The kinetics of high-temperature oxidation of copper of various chemical compositions by gaseous oxygen follows a parabolic rate law within the temperature range of 350–1050 °C. For specialists engaged in the theory and practice of fire refining, of particular interest is the kinetics of copper oxidation over a broader temperature interval of 350–1160 °C. Within this range, the processes include oxidation of solid copper and its melting, oxidation of liquid copper by oxygen introduced into the melt, oxygen solubility in copper, and slag formation. The duration of high-temperature interaction between copper and oxygen has a considerable effect on both the technical and economic indicators of anode smelting and the electrical properties of copper. Therefore, investigating the kinetics of high-temperature oxidation of copper and its influence on the electrical properties of the metal is essential for the optimal organization of fire refining. In the temperature range of 1100–1200 °C, copper oxidation occurs predominantly due to oxygen introduced into the melt with air. The copper(I) oxide formed migrates from the zone of direct contact with gaseous oxygen into the depth of the melt with lower oxygen concentration, where it dissociates into copper and oxygen, thus increasing oxygen concentration in the melt. Overoxidation of copper and excessive saturation of the anode metal with gases lead to its transfer into slag in the form of oxides, to excessive consumption of resources and refractory materials, and to a deterioration of the electrical properties of the metal. To identify optimal oxidation modes and to assess the influence of copper oxidation kinetics on the electrical properties of the melt, a comparative analysis was conducted of the kinetic patterns of oxidation of solid and liquid copper of various chemical compositions under identical experimental conditions, using differential thermogravimetric analysis (DTA) and by surface blowing of the copper melt with an air mixture. The results show that copper samples oxidize at nearly the same rate and that the presence of impurities does not affect the process. All oxygen intended for copper (I) oxide formation dissolves in copper up to the thermodynamic limit (up to 12 % Cu2O). It was established that oxygen concentrations in the melt above 0.06% adversely affect the electrical properties of copper.