Jack Caldwell - Mining Engineer - Robertson GeoConsultants

Just available at this link is the PowerPoint presentation made by Andy Robertson at last week’s conference in Lima, Peru on Mine Water Solution in Extreme Environments. As always, it is fascinating & provocative and informed by his deep understanding of the topic and his international experience looking at mines & tailings dams worldwide.

You must download it and take a look at it yourself if you are even remotely interested in the topic he chooses, namely Challenges, Technology and Solutions for mine water is extreme environments.

I note a few highlights. He starts with a provocative Turkish proverb: “When one man drinks water while another can only watch, Doomsday follows.”

He notes that the earth does not lack water, for it is abundant in oceans, rivers, and lakes. The problem is the heterogeneity of the distribution and quality of water, and the range of biological tolerance to water quality. He notes that with the increasing size of mines, we are increasingly becoming the dominant factor in local water use and impact, and that while mining is transient, many impact on mining are permanent.

His solutions include desalination, treatment to better quality for discharge than intake, and the installation of cut-off walls to prevent contaminant migration.

He notes these consumption rates for tailings disposal:

  • Slurry tailings = 600 liter per ton of ore milled
  • Well-managed slurry (thickened etc) operation = 400 liter per ton milled
  • Filtered, dry stack tailings = 200 liters per ton milled.

The typical city resident uses about 300 liters per day. Thus a 100,000 ton a day mine uses as much water as a town with nearly 200,000 citizens. That is a lot of water.

Thus he concludes that to continue to mine and reap the benefits of the mined resources we need, we have to develop technology to minimize:

  • Water consumption
  • Quality Impacts
  • The residual impacts on the environment
  • The burden we pass on to future generations.

It is a great coincidence that today, the EPAs Bristol Bay (Pebble Mine) assessment is available at this link. Neither Andy nor I seek to wade into this Pebble Mine debate, but it is interesting to lay the EPA.