Hello everyone!

At the end of my previous post, I mentioned how critical it is for an accurate prediction of Acid Mine Drainage (AMD) is to be done as effects on the environment are almost irreversible. It is thus a critical requirement for mine permission and its long-term operation.

Standard protocols for evaluating geological material and their ability to produce AMD have been agreed upon in the scientific community. However, much uncertainty remains in the ability of scientists and engineers to accurately predict the possibility of AMD years into the future, due to the various complex variables that influence acid generation and neutralization (Jennings et al., 2008). Take, for example, the completed Kensington Mine in Southeast Alaska. Due to the presence of neutralizing rocks in the ore, it was not expected to have AMD issues however, in 2007 acidic water was discovered nearby (Coil et al., 2014). Recognizing AMD still remains as one of the greatest environmental problem facing the mining industry and the regulatory agencies.

Here, I would like to focus on Canada’s Mine Environment Neutral Drainage (MEND) Program that was implemented to develop and apply new technologies to mitigate and control acid drainage (MEND, 2020). The program was funded jointly by Natural Resources Canada and The Mining Association of Canada. MEND released a report of potential information required for metal leaching and AMD assessment. This is so that informed decisions can be made with respect to the potential for acid drainage and metal release. These information requirements are summarized in the following statements (Jennings et al., 2008):

  1. General site characteristics: This is a non-exhaustive and site-specific list of information and data that will be essential
  2. Specific material characterization and predictions: To accurately predict the potential it requires a careful and complete characterization of all materials and waste types under the probable weathering (oxygen, bacteria, moisture, volumes of materials, etc.) conditions.
  3. Static and kinetic tests: Static testing is the laboratory analysis of geological material for chemical characteristics. Kinetic testing is using data obtained to simulate actual field site weathering for over a long period of time
  4. Assessments of waste materials: Waste materials include waste rock, tailings, treatment wastes, low-grade ore, and overburden materials. All media require assessments and predictions for acid drainage and releases of metals. 

The MEND report also provides ways to interpret and display the above characterization data.

From the above, one can tell that a lot of data are required and the processing of data is a problem. In addition, it is difficult to evaluate the synergistic effects of the various characteristic, therefore often underestimating the impact. There are also additional issues like the surrounding environmental condition that could play a part. A study (Kuipers et al. 2006) was conducted to compare predicted and actual water quality at several hard rock mines in the United States to examine the reliability of pre-mining water quality predictions. Data analyses show that the majority of the predictions actually failed. Despite efforts taken to assess the potential of AMD, most are unable to accurately do so either underestimated or ignored the potential. 

The difficulty to accurately assess AMD and metal release makes it, even more, challenging to put mitigation strategies in place resulting in significant pollution events. More research and efforts would be needed to improve the mining industry in order to mitigate such pollution events and be a more sustainable industry.

That brings me to the end of this post

See you guys soon!

References

Coil, D., McKittrick, E., Mattox, A., Hoagland, N., Higman, B., & Zamzow, K. (2014, October 29). Acid Mine Drainage. Retrieved September 25, 2020, from http://www.groundtruthtrekking.org/Issues/MetalsMining/AcidMineDrainage.html

Jennings, S. R., Neuman, D. R., & Blicker, P. S. (2008). Acid Mine Drainage and Effects on Fish Health and Ecology: A Review. Retrieved September 28, 2020, from https://www.earthworks.org/cms/assets/uploads/2018/12/55-S.R.-Jenning-et-al.-2008.-Acid-Mine-Drainage-and-Effects-on-Fish-Health-and-Ecology-A-Review.pdf.

Kuipers, J. R., A.S. Maest, K.A. MacHardy, and G. Lawson (2006). “Comparison of Predicted and Actual Water Quality at Hardrock Mines: The reliability of predictions in Environmental Impact Statements.” Kuipers & Associates, PO Box 641, Butte, MT USA 59703.

MEND. (2020). MEND. Retrieved September 28, 2020, from http://mend-nedem.org/default/