In Situ: A Mining Solution?

I recently did a post discussing the hazards of Uranium mining in which I focused on traditional surface and shaft type mines.  If you didn't see the post, you can read it here.  In the article I mentioned  a type of mining known as in-situ leaching.  I didn't talk about it much there because I feel that it was worth discussing as its own subject.

I first heard about in-situ leaching in my stewardship of nuclear materials class earlier this semester.  It caught my interest because my professor, which is an environmental scientist seemed to be excited about the benefits of this method of Uranium extraction.  Thus, I had to do some research and learned that this method actually mitigates many of the negative effects of tradition mineral mining methods.

So what is in-situ leaching?  In brief, it is a type of mineral recovery that does not involve the removal of mineral ore from the ground.  Instead, in-situ leaching injects a solution into the ground which dissolves the mineral from the rock and then and then pumps the solution back to the surface.  At the surface, the mineral is separated from the solution, yielding relatively pure Uranium oxide.  The picture below is a diagram of a in-situ leaching system.

Image taken from http://www.wise-uranium.org/uisl.html

As can be seen in the image, this type of mineral recovery only works when the mineral is confined between two layer of solid rock which prohibits the leaching liquid from passing through.  This is to make sure that the leaching liquid does not escape into ground water areas and contaminate our drinking water.  Contamination of the ground water is the largest concern with this type of mineral recovery.  It does happen that the leaching solution leaks through the confining boundaries into the ground water, making this method  a little nerve racking to those who depend upon the water.  This risk though is small and does not contaminate the water in large concentrations.

So why don't we use more of this method for Uranium mining seeing that it gets rid of the need to remove large amounts of land and leave large tailing piles behind?  Well first of all, in-situ leaching is not good for removing large amounts of Uranium.  It is instead an good method extraction where there is a low concentration of Uranium in the ore.  This method is much cheaper than traditional mining practices and thus makes getting lower concentrations out of the ground more efficient.  It cannot replace traditional Uranium mining though due to its limits.

From an environmental standpoint, leaching does permanently change the composition of the rock.  Some are opposed to this method for this reason.  I say that this method is much less destructive than digging up large amounts of ore to extract the Uranium.  And besides, how can we extract any mineral without affecting the rock it is contained withing.  I think a little common sense is needed here...we need Earth's resources to live modern life.  We need to accept that taking these resources out of the ground is a part of life.

Is in-situ leaching an alternative to traditional mining techniques?  I think probably not, but it is an efficient way of extracting low concentrations.  We still need to mine Uranium though.  I don't see a way around it, but like I have already said:  such is a product of the lives we choose to lead! 

Do some further reading on in-situ leaching here.  This is the site I used, so let me know if you disagree with my opinion.