Mining: some reasons why tailings can be so problematic

Self-tutoring about environmental issues: the tutor looks into possible dangers surrounding mining tailings.

Herein, tailings are defined as mining leftovers or mining results that are left behind.

Occasionally one hears about mine tailings causing a problem in the environment. Usually it’s in a part of the world where mining isn’t well regulated, or else it’s at an old facility that was mined before regulations applied there.

As I understand, unattended mine tailings can produce very serious environmental damage, to the point that it’s dangerous even to be around them, or to be exposed to water downstream from them. From a chemical point of view, there are two reasons why:

The first reason is that, often, the mined-for items (eg, metals) are found in sulfide form or else alongside other sulfides. The sulfides left behind in tailings may become sulfuric acid once exposed to the environment. Sulfuric acid, past a certain concentration, can kill most life in an aquatic environment; high enough, it can even attack a person’s skin if they enter that water.

Another reason why tailings can be toxic is that toxic ingredients might be added to the ore to extract the goodies. Gold is an example: mercury or cyanide is sometimes used to separate it from the ore. Said mercury or cyanide may then be left in the tailings. If said tailings aren’t properly contained, the mercury and/or cyanide can leach out and create a toxic environment.

My understanding is that nowadays, in most developed countries, mining projects must follow strict guidelines of tailing treatment and/or containment. Older projects, however, may have left tailings behind that still poison the environment. Unfortunately, in some parts of the world, mining is still improperly regulated, and local people can be poisoned when a government allows an irresponsible mining project.

earthworks.org

www.europarl.europe.eu

epa.gov

novascotia.ca