Mine tailings waters

Elberling, B. and R. V. Nicholson. 19%. Field determination of sulphide oxidation rates in mine tailings. Water Resources Research 32(6) 1773-84. 

Exposure of humans and wildlife to arsenic may occur through air (emissions from smelters, coal-fired power plants, herbicide sprays), water (mine tailings runoff, smelter wastes, natural mineralization), and food (especially seafoods). 

Although additional analyses of the existing data and additional experiments are required to reach definitive conclusions on the phase changes of ferrihydrite in uranium mine tailings, preliminary XRD data suggest that in deionized water at elevated pH (pH=10) phase transformation of ferrihydrite can occur at elevated temperatures. In both elevated temperature experiments, hematite appeared to be the dominant transformation product. At room temperature, however, ferrihydrite remains stable after the duration of the experiment (seven days). 

All mine surface water in direct contact with the tailings is characterized by low pH (2.0-3.5) and a large amount of dissolved solids (1,400-17,000 ppm TDS). Average concentrations of elements in solution... 

The uranium mine tails contain the equal masses of water and solids. Furthermore the treatment of each ton of uranium ore is accompanied by receiving about 3 tons of rafinate, and finally the treatment of 1 ton of uranium ore gives about 4 tons of liquid wastes of different chemical composition, which in turn depends on the treatment technology. 

Davis et al. (1999) used EMPA, pore water analyses, and geochemical modeling to show that overbank deposits of mine tailings from Butte, Montana, that were treated with lime or revegetated had significant relative levels of plumbogummite that controlled Pb in pore waters. 

Jarosites are generally less soluble in acidic waters than under alkaline conditions. Although As(V) is known to partially substitute for sulfate in the mineral (Savage, Bird and Ashley, 2000), controversies exist over whether jarosites preferentially sorb more arsenic than their frequent decomposition product, goethite (Acero et al., 2006, 4137-4138). Examples of exceptionally arsenic-rich jarosites occur in mine tailings at Enguiales, Aveyron, France, where arsenic concentrations are approximately 5.7 wt% (Courtin-Nomade et al., 2003). 

Sometimes clay layers are inserted into mine tailings piles (e.g. Globe and Phoenix Mine in Zimbabwe) or piles are capped or surrounded with clay or plastic liners. The liners and caps are installed to reduce the infiltration of air and oxygenated water, and hinder the formation of mine drainage (Williams, 2001), 275. 

---