The adsorption characteristics and performance of gold onto elemental carbon extracted from refractory carbonaceous gold concentrate

Refractory carbonaceous gold concentrate contains carbonaceous matters that seriously interfere with the gold extraction process. Therefore, the in-depth experimental studies on the gold-adsorption performance of elemental carbon extracted from refractory carbonaceous gold ores is of significant importance, carried out in this article. Various factors affecting the gold adsorption process are investigated, including the variations of pH, temperature, adsorption time and initial gold concentration. Moreover, the kinetic and isotherm models asso-ciated with the adsorption process are established to describe the adsorption behavior. A variety of analytical methods, such as SEM, BET, XRD, FTIR and Raman spectroscopy were used to clarify the adsorption mechanism. The results obtained suggest that the maximum adsorption rate (99.34 +/- 0.25%) can be obtained at the pH value of 3.0 at 35 celcius, when the adsorption equilibrium is reached within 10 h. The gold-adsorption behavior of the extracted elemental carbon conformed to the pseudo-first-order and Freundlich model, where the limiting step in the adsorption process is based on the surface diffusion mechanism. The adsorption process was spontaneous and endothermic, accompanied by an activation energy of 8.87 kJ.mol(-1). Furthermore, the isosteric heat of adsorption increases as the amount of adsorbed gold at equilibrium increases. Significantly, the gold adsorption process is predominantly physisorption-driven associated with the pore structure, the surface defects and the active sites of the extracted elemental carbon. And XPS analysis suggested that gold was adsorbed on the elemental carbon surface in the form of Au(III).

Automated summary

In this study, the gold adsorption performance of elemental carbon extracted from refractory carbonaceous gold ores was extensively investigated. Various factors affecting the adsorption process were studied and kinetic and isotherm models were established to describe the adsorption behavior. Analytical methods such as SEM, BET, XRD, FTIR, and Raman spectroscopy were used to elucidate the adsorption mechanism. The results showed that the adsorption process was pH and temperature dependent, and the gold adsorption behavior followed the pseudo-first-order and Freundlich model.