Traditional mine tailings disposal has been to deposit a slurry of saturated material into an impoundment or dam. The tailings may come from a floatation circuit and have very small grain size and high water retention capacity. Typically, they also sit above a basement (usually crystalline) bedrock, unlined. A major concern with these facilities is the long-term geotechnical stability and the retention of high levels of metals.
HGI is well versed in the unique issues related to mine tailings. Whether geotechnical, hydrogeological, or environmental, geophysical tailings characterization and monitoring can help decrease environmental impacts.
Unlike heaps, where moisture in the pile is controlled, tailings will have significant water and provide a large gradient for transport of the metals. This solution may leave the site and impact groundwater, wetlands, and streams nearby. Fortunately, there are mining geophysical methods available to provide reconnaissance-level characterization to trace the contaminants from source to impacted area. The composition that makes the tailings water dangerous to the environment happens to be the best target for mining geophysical methods due to the waste’s ability to readily transmit current, By using technologies such as electrical resistivity, induced polarization (IP), and thermal monitoring the solutions generated in tailings piles can be tracked to their original sources so controls can be implemented to stop flow into unwanted areas.
Impoundment dams holding mine tailings offer another opportunity to apply robust geophysical methods, such as seismic refraction or multi-channel acquisition of surface waves (MASW). For more information, visit our sister site dedicated to impoundments and dams HGI’s Dam Assessment Page.