Kinetics of the Deoxidation of Cu Melt Using CH4 Gas Bubbling

초록

Improving the efficiency of copper (Cu) fire refining is essential for reducing energy consumption and environmental impact. Although methane (CH4) gas is often used as a reducing agent in the Cu fire refining processes, the kinetic mechanism of deoxidation using CH4 (g) remains insufficiently understood. This study aims to elucidate the rate-controlling step of the deoxidation of a Cu (l) melt using a methane-argon (CH4-Ar) gas mixture bubbled in the temperature range of 1423-1523 K. The effects of total gas flow rate, partial pressure of CH4, and reaction temperature on the deoxidation rate were investigated. The overall deoxidation reaction of the Cu melt comprises the mass transfer of CH4 in the gas boundary layer, mass transfer of dissolved oxygen (O) in the liquid boundary layer, oxygen-promoted decomposition of CHx (1 <= x <= 4) at the reaction interface, and the subsequent deoxidation by carbon (C) and hydrogen gas (H2). From the analysis of the first-order reaction rate equations, the decomposition of CHx at the reaction interface was determined to be the rate-controlling step of deoxidation under the investigated conditions. The activation energy of deoxidation reaction was calculated to be 183.1 kJ & sdot;mol-1 in the range of 1423-1523 K.

키워드