Abstract:Humic acid extraction from carbonaceous pressure-oxidized gold ore was carried out. The structure of humic acid was analyzed utilizing elemental analysis, FTIR, UV-Vis, Raman spectra and XPS. Also, the kinetic and isotherm models of the gold-adsorbing process were established to calculate the thermodynamic parameters and isosteric heat of adsorption. The results showed that affected by pressure oxidation, the aliphatic structure, C=O and other oxygen-containing groups were destroyed. Most importantly, new bonds, such as C—O—Cl_x, C—Cl_x and Me₄N—Cl, were formed in the humic acid extracted from pressure-oxidized gold ore. The adsorption test results showed that, pressure oxidation made a profound impact on the gold-adsorbing performance of humic acid. The adsorption rate of humic acid decreased to (42.78±1.05)% for the pure gold solution and (28.63±1.11)% for the gold leaching solution after pressure oxidation. Adsorption findings conformed to the pseudo-second-order and Langmuir isotherm models. The isosteric adsorption heat of humic acid increased with the increase of the adsorption amount.

Key words: humic acid; orthogonal experiment; pressure oxidation; structural change; adsorption behavior