Abstract:The decomposition and gold adsorption experiments on humic acid under various hot-pressing oxidation conditions were conducted. Structural changes in humic acid were analyzed using Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), and scanning electron microscopy (SEM) to investigate the impact of hot-pressing oxidation on the "preg-robbing" properties of humic acid in carbonaceous gold ores. The results demonstrate that the decomposition rate of humic acid reaches its maximum value of 79.8% under the conditions including temperature of 225 °C, initial pH value of 10 and reaction time of four hours. Conversely, the adsorption rate of humic acid to gold is minimized to 52.11% under the conditions including temperature of 250 °C, initial pH value of 2.5 and reaction time of three hours. FTIR analysis indicates that during the hot-pressing oxidation process, humic acid generates intermediate products such as hydroxyl groups, alcohols and phenols. Higher temperatures are not conducive to the further decomposition of these intermediates. Under alkaline conditions, phenolic groups within humic acid exhibits resistance to decomposition. Additionally, alcohol-phenol groups and amine substances are produced during hot-pressing oxidation, and these compounds can undergo further oxidation with extended reaction times. UV-Vis spectroscopy reveals that humic acid contains conjugated C=O and C=C structures, which remain unaffected by thermal pressure oxidation. SEM analysis demonstrates that the morphology of humic acid undergoes significant changes following thermal pressure oxidation, thereby altering its "preg-robbing" properties in carbonaceous gold ores.