Critical Review of Field Studies of Chemical Surface Coatings to Mitigate Leaching from Mining Wastes

Source control of mine drainage and leachate from mining wastes is ideal, but there is limited use of control methods aside from removal of wastes to repositories or capping wastes in situ. In some locations, neither removal nor capping is possible; thus, there is renewed interest in understanding technologies for coating mining wastes. This paper presents the current state of knowledge from a critical review of the few field case studies where chemical coating technologies have been applied to mined surfaces (e.g. a highwall) or mining wastes. It also includes laboratory studies where the same technology was examined on the same type of waste material as the field studies. The chemicals used in field studies for coating mining wastes were magnesium oxide, potassium permanganate, silicate compounds, phosphate compounds, and a furfuryl alcohol resin sealant. Descriptions of the methods employed, and results obtained are provided. Limitations of the individual studies and of the technologies in general are discussed. Potential reasons why coating technologies have not been commonly used are presented, along with further research needs.