Open pit mining

Gold jeweleries are the most utilized accessories for defining personal style. However, there are few informations known to those who wear them regarding the hard work required to produce jewelery and, most of all, the consequences for our planet. Nuggets glittering in riverbeds are the realities of other epoques. Most gold these days comes from large open-pit mines, where huge amounts of rock are churned up to extract tiny flecks of precious metal. A “rich” mine might contain just a few tenths of an ounce of gold per ton of ore; a “poor” one would have a few hundredths of an ounce per ton. Earthworks estimates that a standard 18-karat wedding band leaves behind <ahref=”http://nodirtygold.earthworksaction.org/library/detail/how_the_20_tons_of_mine_waste_per_gold_ring_figure_was_calculated#.UtqQ92T8LZs”>20 tons of ore and waste rock.
International demand for gold and other metals triggered the interest of multinational companies for new forms of exploitation involving very little respect for the environment. Benefits remain fully available to mining companies, while local communities face serious risks to human health and the environment.
In many cases, extensive cutting and burning of woodland vegetation above the deposit precedes the exploitation. Open pit mining is used in deposits with low concetrations, that were previously considered unprofitable. The depth of the mine goes far beyond the limit of the groundwater. In this case, the groundwater combined with heavy metals must be pumped out of the pit. However, after closing the mining operation, water accumulates at the bottom of the quarry, especially after water pumps stop. The impact of mining operations, in all of it’s stages, it is signifiant for the environment: (a) Exploring and extracting the deposits, (b) Preparing the mining operations, (c) Exploitation itself and, (d) Further treatment of the ore obtained in order to obtain a commercially profitable production.
Moving such a large quantity of earth and stone requires a lot of energy. Their excavation leads to the production of acid water drainage, that is, in fact, the most common environmental concern caused by open pit mining. When you dig up rock that’s been buried for a long time, air and moisture can set off chemical reactions that produce acids and leach toxic metals. If those substances — sulfuric acid, arsenic and copper, for example — run off into lakes, rivers and streams, they will pose serious risks for populations of fish and other aquatic organisms. Mine drainage is a problem for many kinds of operations, but it’s especially significant for gold extraction. For one thing, gold is often found in rock that contains a lot of acid-generating sulfides; for another, mining gold produces much more unwanted rock than does mining other minerals.

Big mining operation often use, in the extraction process, cyanides. Cyanide is extremely toxic, and the problem is that it allows the mining companies to extract metals from very poor ores. In the process of gold extraction, large quantities of sodium cyanide are used, a very poverful substance, that retrieves gold from other materials eliminated during processing. This chemical product has harmful effects on human health, even at low doses, can affect the respiratory, cardiovascular, gastrointestinal, neurological, ocular and dermal system, because it can be absorbed by skin contact. Health effects can last for months or years, from cancer risk to reproductive problems, hyperthyroidism or permanent damage to the nervous system.
Mining producers end up digging up more land to produce the same amount of gold, resulting, in exchange, huge amounts of sterile, a material remaining after processing ore. Tailing ponds are full of toxic substances such as arsenic, cyanide and mercury waste. Therefore they must be handled carefully to prevent mining accidents, especially since these ponds can remain toxic for centuries.
Moreover, open-pit mining has the following consequences:
– The environmental change, changes in the the morphology of the land and storage of large quantities of waste hazardous to health. Often, water courses are modified and new dams are created to keep the tailing ponds.
– Contaminated water. Basins and dams poorly designes or inadequately maintained contaminate surface water courses . Water leakage contaminated with chemicals and reagents used in the extraction process can reach groundwater that is usually used as drinking water.
-Soil contamination. This type of mining process completely eliminates soil in the mining area , contributing to erosion of the peripheral areas.

Mining companies, generally, do not assume responsibility for accidents, and mine closure costs are rarely covered.

Material adapted from:
Production of gold has many negative environmental effects.
La minería a cielo abierto.