Stabilization and encapsulation of arsenic-/antimony-bearing mine waste: Overview and outlook of existing techniques

Arsenic and antimony are metalloids that exhibit similar geochemical behavior and are often found in the same mineral associations, co-occurring in mine waste derived from ore exploitation. Due to their adverse effects on ecosystems and human health, techniques to limit their release into the environment from mine wastes and the consequent pollution of surrounding areas are of great interest. This review addresses the geochemical behavior of these two metalloids in mining environments and presents an overview of the main strategies used to stabilize or encapsulate As- or Sb-bearing mine waste, highlighting and comparing their shortcomings and advantages. Several approaches have been investigated, including the 1) establishment of surface covers, 2) application of amendments, 3) solidification using cementing or geopolymer, and 4) application of protecting coatings. Several of these methods have exhibited potential for treating As mine waste. However, the weathering state, composition, and final fate of wastes are determining factors affecting treatment effectiveness. Regarding Sb mine waste, only cementation processes have shown some good performance. Further research effort is required to develop effective passivating coatings or stabilization methods to treat these mine wastes.