Mine Rehabilitation Is Important – Here’s How To Prepare

14

MAY, 2019

Mining
Sustainability

The method in which a mine is rehabilitated after the operational stage has ended, is arguably just as important as the development. Many current laws around the world require that mine plans include closure plans from the very start of the mining operation. For existing mines, comprehensive closure plans are often required to be put into place as soon as possible.

Most laws are devised in this strict manner to prevent potential danger to both public and environmental health. One possible danger lies in the water that accumulates in the mine. The mine waste water dilutes the toxic metals and chemicals used and/or mined during its operational stage.  These materials could potentially include heavy metals or cyanide. A lake laced with toxins is an obstacle in and of itself. In some cases,  polluted bodies of water can cost billions of dollars to resolve. When the polluted water spreads, safety hazards multiply.

Safety Hazards to Consider

In 2015, the Gold King Mine in Colorado, flooded nearby rivers with a powerful surge of contaminated water. The flow persisted for more than a year after the spill first began. At one point, an estimated 500 gallons of polluted water were dispersed every minute. Hundreds of other abandoned mines are tainting nearby rivers and streams much like the Gold King Mine.

The image below displays a body of water that filled an excavated mine in the Philippines. It seems aesthetically pleasing but there are speculations that this particular mine lake is contaminated by cyanide- though not confirmed.

Non-Rehabilitated Mine in the Philippines, rumored to be laced with cyanide 

For retired mines that did not fill with water, risk still remains eminent due to the potential air pollution. The chemicals and metals left in the mines can be dispersed by wind or fire. The Hazelwood Mine Fire in Australia caused serious illness and deaths in nearby residents after the toxic smoke traveled via wind. Whether pollution travels via air, water, or doesn’t travel at all – it can and should be avoided.

Optimal Mine Rehabilitation Methods

The focus of mining rehabilitation is to minimize environmental changes caused by the mine’s operations. Ideally, a properly retired mine will be indistinguishable with the surrounding land. This means it will be as close to its original state as possible and, perhaps most importantly, free of any harmful materials.

That being said, mine rehabilitation starts far before the operational stage ends. For example, the less waste there is during the production, the less waste there is to mitigate after production. Some rehabilitation tips to consider during operation include:

  • Minimize water consumption throughout the operation and the potential water borne emissions will be minimized as well.
  • Sort all reactive and hazardous substances separately to lessen the chance of generating hazardous waste. 
  • Keep and properly sort soil mass in order to utilize it for the earthworks of the closing phase.

Mines operate for long periods of time which mean the closing plans are prone to reconfiguration. These recommendations, however, can be enacted no matter what the rehabilitation plan entails. Each mine is unique, so closure and rehabilitation plans will differ for each one. That being said, these pre-rehabilitation actions are universally applicable.

A properly rehabilitated mine in Australia. 

Innovative Mine Rehabilitation

An innovator for mine rehabilitation, Michigan Technological University, is studying whether abandoned mines in their state can be transformed into valuable energy storage. The project involves using the underground components of the abandoned mines for pumped hydro storage.

The two year pilot project will focus on the Mather B Iron mine which closed in 1979. This is the first of many abandoned mins to be transformed. The outcome and success of this soon to be transformed mine will determine whether the others are to be converted as well.

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