Effects of Temperature on the “Preg-Robbing” Ability of Organic Carbon in Carbonaceous Gold Ore During Vacuum Roasting Pretreatment: Anthracite as a Model

Abstract

In this study, anthracite has the most similar “preg-robbing” characteristics to the organic carbon of carbonaceous gold ore. Vacuum roasting experiments were conducted on anthracite as a model of organic carbon to investigate the impact of temperature on the “preg-robbing” ability of organic carbon in carbonaceous gold ore during the vacuum roasting process. The changes in the pore structure, functional groups and carbon structure of anthracite were characterized using different analysis methods. The results showed that the anthracite thermal decomposed in the vacuum roasting process. The gold adsorption rate of anthracite decreased sharply from 97.48% (800 °C) to 4.67% (1200 °C), representing the main change stage of its “preg-robbing” ability. The morphology and pore structure of anthracite had no obvious change during the whole roasting process, the rapid disappearance of anthracite functional groups mainly occurred below 800 °C. These results all suggested that the “preg-robbing” ability change of anthracite was not caused by its pore structure or functional groups. The change in anthracite’s carbon structure was consistent with the change in its “preg-robbing” ability. The anthracite entered the graphitization process around 800 °C upon increasing temperature, the internal carbon structure gradually changed from the disordered state to an orderly state. With increasing graphitization degree, the gold-adsorption ability was reduced. The transition of carbon structure from disordered to ordered state during vacuum roasting might be the key reason for the decrease in the “preg-robbing” ability of organic carbon. This study established a direct correlation between graphitization degree and preg-robbing capacity reduction, providing a novel strategy for optimizing gold recovery in refractory ores.