Transformation of typical heavy metals during preparation of porous carbon from coal gasification fine slag

Abstract

To clarify the fate of typical heavy metals during preparation process of porous carbon, we produced porous carbon using a two-step strategy and investigated the transformation behavior of heavy metals including V, Cr, Mn, Cu, Zn and Ba in the process. A modified Community Bureau of Reference (BCR) sequential extraction procedure was implemented to reveal the occurrence state of heavy metals. The results clearly showed that the transformation of selected heavy metals in activated carbon was mostly determined by the occurrence state, volatile nature and operating procedure. In addition to the new aluminosilicate minerals, abundant pore structure also had evident dependence on solidifying heavy metals in porous carbon. The content of heavy metals in activated carbon were considerably lower than YKFS, and V, Cr and Cu were more accumulated in porous carbon. It is also important to note that Zn possessed markedly lower content and REI value (3.61–56.17 %) in activated carbon and porous carbon owning to the volatile nature of Zn and acid solubility of Zn-base minerals. The Risk Assessment Code (RAC) evaluation conducted that the acid leaching operation effectively decreased the hazardous properties of heavy metals. The research results can provide significant guidance for value-added utilization of gasification fine slag in an environmentally friendly.