Saturday, November 3, 2007

Pascua Lama Gold Mine: A Contemporary Quest for El Dorado

Pascua Lama Gold Mine Background

Pascua Lama is a mining project consisting of the open-pit exploitation of a deposit of gold, silver and copper ore and its processing to produce doré (gold and silver) and copper concentrate.

The deposit is located high in the Andes on the Chilean-Argentinean border, about 150 kilometres to the south-east of the city of Vallenar in the Commune of Alto del Carmen, Province of Huasco, III Region of Chile.

The nearest communities are Chollay and Las Breas, located 35 and 55 km away, respectively.

The project is bi-national in that it will have workings and operations in both Chilean and Argentine territory. In Argentina, the project is located about 300 km to the north-east of the city of San Juan, in the Department of Iglesia, Province of San Juan.

The operational area is established according to Additional Protocols 20 and 23 of the 16th Economic Complementarity Agreement of negotiated between Chile and Argentina within the framework of the 1980 Treaty of Montevideo.

A large part of the open pit will be in Chilean territory, as well as a waste rock dump, the processing plant, primary crusher, mine equipment maintenance complex, and powder magazine for the storage of explosives.

These facilities will be located in the headwaters of the Estrecho River, tributary of the Chollay River, at 4,400 metres above sea level.

In Argentine territory a smaller portion of the open pit will be built, along with a waste rock dump, a processing plant, a tailings pond, the construction camp (for 4,000 people) and operation camp (for 1,000 people), in addition to a private aerodrome.

The ore will be extracted of the mine at the rate of 15 million tons per year and sent to a primary crusher in Chilean territory, to reduce its size. Then it will be transported by means of a conveyor belt to processing facilities located in Argentine territory, crossing the border through a 2.7 km long tunnel.

In the processing plant the ore will undergo secondary crushing, milling, and washing operations.

The so-called refractory ore will be processed by means of conventional flotation to obtain copper concentrates. The non-refractory ore, as well as wastes from the flotation circuit, will be processed by means of leaching with sodium cyanide, precipitation with zinc, and refinement to obtain “doré” metal.

The water requirement for the Pascua-Lama Project will be 370 l/s in total. This demand will be supplied from the Taguas River in Argentina.

Barrick is proposing to extract additional water in Chile for the operations of the mine and factories, with an estimated requirement of up to 42 l/s that will be taken from the Estrecho and Toro rivers. Barrick will have the corresponding utilisation rights under the legislation of each country.

There will be terrestrial access from both sides of the border. In Chile access will be from the city of Vallenar, via the road that connects Vallenar with the Alto del Carmen area, followed by a secondary road to be developed up the entire Carmen River valley.

The amount of the investment has been estimated to be 950 million dollars.

The Project has a productive life of 20 years according to the present reserve estimates, and it will produce 5,000 tons of copper in concentrates, 615,000 ounces of gold and 18.2 million ounces of silver annually.

The companies developing the project are: Company Minera Nevada S.A. in Chile, and Barrick Exploraciones Argentina S.A. and Exploraciones Mineras Argentinas S.A., in Argentina.

Glacier removal and handling

The information available in the EIA only establishes that this will have an approximate surface area of 10 hectares and that “the sectors of glacier that will have to be removed will be determined with the appropriate lead time in accord with the updated mining plan.” There are no estimates of thickness or the equivalent in water.

The lack of relevant technical expertise in removing glaciers implies an irreversible environmental impact. What is certain is that the three affected glaciers would suffer an environmental impact. Nevertheless, there is no certainty whatsoever of what the impact would be on glaciers or permafrost (frozen rock or soil) from the road network and the associated stabilization measures that generally involves the use of salts.

Here is the full article.