Degradation of hydroxyoxime CP-150 in the presence of nitrate and permanganate ions causing detrimental effect on copper extraction

Abstract

Hydroxyoxime is the most widely used extractant in copper hydrometallurgy. However, due to the unstable structure of hydroxyoxime and the complex and harsh actual operating environment of the copper extraction system, the failure of hydroxyoxime in the copper extraction process due to degradation is of great concern. Currently, most studies mainly focus on verifying the influence of various potential factors on the degradation of hydroxyoxime extractants without considering the operation of the whole system, resulting in its failure problem not being effectively solved. In this paper, the operation of the extraction system was systematically analyzed with the issue of degradation failure of hydroxyoxime extractant in copper extraction and recovery process in the comprehensive recovery of gallium‑germanium copper in Shenzhen Zhongjin Lingnan Nonfemet Co., Ltd. Combining the effects of (i) acidity, (ii) copper ion concentration, (iii) NO3− and (iv) MnO4−, the effect of NO3− on extractant degradation was found to be more prominent, and the nitrification degradation (ND) rate was greatly affected by concentration and temperature. The MnO4− ion is a strong oxidant at high acidity. Its role on oxidation degradation (OD) of hydroxyoxime extractants was limited during the actual operation, overturning the common perception that strong oxidizing MnO4− is the leading cause of OD of hydroxyoxime extractants. Controlling the operating temperature of the extraction process is essential to prevent extractant degradation. In addition, GC–MS and FITR analysis of complex degradation products further validated the hydroxyoxime ND mechanism, which is of great practical significance for controlling the degradation of hydroxyoxime extractant in the copper extraction and recovery process from the origin.