Removal and Reclamation of Trace Metals from Copper and Gold Mine Tailing Leachates Using an Alkali Suspension Method

Abstract

Leachates from mine tailing ponds, which usually contain a variety of metallic ions, are highly toxic to human and ecological health. The common methods used to remove those trace metallic are difficult due to the extremely acidic conditions and the diverse kinds of metals in mine tailing leachates. Herein, we proposed an economical and efficient soil-assisted alkali suspension approach to remove and reclaim the trace metals. Under the optimum conditions, more than 98% of Cu2+, Zn2+, and Cr3+, and 93% of Cd2+ were removed from authentic copper and gold tailing leachates. Multiple characterizations indicated that the quick removal of trace metal ions from leachates was mainly due to the formation of amorphous hydroxides which are easily adsorbed by soil particles. Additionally, small quantities of metal ions and organic matter complexes were formed, which contributed to the removal of trace metals. Furthermore, most of the adsorbed trace metal in authentic tailing leachate can be reclaimed by a simple acid treatment. Life cycle assessment analysis demonstrated the environmental sustainability of this alkali suspension method due to its smaller contribution to global warming. This study provides an efficient and low-cost approach for the disposal and recycling of toxic mine tailing leachates.