Jared Diamond wrote about this a few years ago in his book, Collapse.

In response to Todd, yes, the companies are obligated to clean up their messes, but the easy loophole is that these groups create a new corporation for each mine. Then they file for bankruptcy as soon as the gold is all mined, and dissolve the corporation. The laws do not hold individual owners responsible for environmental damage, only the corporation. The same people then move on to another mine and do the exact same thing over again.