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Response to TexasTowelie (Original post)

Wed Mar 13, 2013, 03:31 PM

22. Some facts I recently dug up about gold mining...

 

Enormous amounts of earth must be mined to produce a vanishingly small quantity of gold. Here's the data from one viable mine belonging to GFI - Gold Fields International, South African company - at the Tarkwa mine in Ghana.

See http://www.goldfields.co.za/ops_int_tarkwa.php

The data GFI presents on the table at that page shows that in 2011, 117,156 kt of earth (i.e., kilotonnes, meaning 117,165,000 tonnes a.k.a. 117.2 million tonnes) were extracted from the "open pit surface operation" at Tarkwa to gain 21,876 kt of ore (meaning 21,876,000 million tonnes a.k.a. 21.9 million tonnes).

The table helpfully notes that this makes for a "Waste:Ore" ratio of 4.4 metric tonnes of waste for each single metric tonne of ore mined. However, this figure, given in the top section of the table, is not fully relevant to the environmental impact, because the 21.9 million tonnes of "ore" is itself almost entirely waste. The final product in pure gold for the market, as far as I know the only marketable thing produced by this operation, is 22.3 tons of pure gold. That means it takes about a million tonnes of ore to produce one tonne of product.

In giving the figure for the final gold product, however, the table switches to kg and presents it as 22,312 kg (so kt for "Total mined" at the top of the table but kg for "Total Gold Produced" towards the bottom). This convention means both the original "Total mined" and the "Total Gold produced" figures are rendered in the table as five digits, although if compared directly in the same unit of measurement they differ by six digits (a factor of X times 10^6).

Bottom line, the Ghanaian mine produced 22.4 tons of pure gold (also given as 717,000 oz) after digging out 117,000,000 tons of earth, which means 5.4 million tonnes of earth extracted per tonne of gold.

And this doesn't even begin to cover the water and chemicals and energy involved in the separation of the ore from the "waste" earth and the processing of the ore to produce the pure gold. All this to get a shiny, beautifully malleable metal that is already in abundance for its industrial uses; but that remains in far higher demand because some people will always believe it is God's Money and an even larger number persist in the belief that it is the True Symbol of Love.

To sum up, the real waste-to-product ratio in gold mining appears to be 5.4 million:1. This will differ at various locations, but it will still be millions to one. I didn't even believe it, so I invite anyone to check the above arithmetic. For example, am I mistaken in my understanding of the relative meanings of kt and kg as used in the GFI table?

Gold Fields International in the above linked web page wrote:

West Africa is host to world-class gold deposits and is a premier mining destination. The Gold Fields brand is strong in the region and Tarkwa is ideally positioned to fulfil the Gold Fields vision “To be the global leader in sustainable gold mining”.

PRODUCTION: 22,312 kg (717,000 ozs) TOTAL CASH COSTS: US$552/oz

Gold Fields Ghana Limited (GFGL) was incorporated in Ghana in 1993 as the legal entity holding the Tarkwa concession mining rights. Gold Fields Ghana Holdings Limited now holds 90% of the issued shares of GFGL after acquiring the indirect 18.9% of the issued shares belonging to IAMGold and its affiliates. The government of Ghana holds a 10% free carried interest, as required under the mining law of Ghana. The Tarkwa Gold Mine operates under seven mining leases covering a total area of approximately 20,825 hectares.

The Tarkwa Gold Mine is located in southwestern Ghana near the southern end of what is commonly referred to as the Tarkwa Basin, 300 kilometres by road west of Accra, the capital of Ghana, and is easily accessible with an established infrastructure.

The open pit surface operation exploits narrow, tabular auriferous conglomerates similar to those mined in the Witwatersrand Basin of South Africa. Mining is currently taking place from six pits, Pepe, Atuabo, Mantraim, Teberebie, Akontansi and Kottraverchy and the mine utilises a conventional CIL plant as well as a heap leach facility. In the twelve months ending December 2011, Tarkwa produced 717 koz of gold from the milling and heap leach operations at a cash cost of US$552/oz.


Hmm, Tarkwa Basin... isn't "basin" a geographical feature somehow related to water?

A friend added:

Jack, Frontline partnered with the NY Times some time ago and produced a very good series disclosing environmental and political corruption that goes hand-in-hand with this extractive technology.

The six Times articles related to this series had great photos and ran from October 24 to December 30, 2005.

Here's The Frontline home page for this series, Peru, The Curse of Inca Gold, October 2005
http://www.pbs.org/frontlineworld/stories/peru404/

From, The Toxic Shimmer of Gold,
http://www.pbs.org/frontlineworld/stories/peru404/environmental.html

"Today most mining operations use a process called heap-leaching, where gold is chemically sifted from huge piles of low-grade ore using a water-based sodium cyanide solution. To get a sense of the scale of the process, at the Yanacocha mine in Peru for example, Newmont Mining must extract and leach approximately 30 tons of dirt and rock to recover just one ounce of gold."

The videos are powerful,
http://www.pbs.org/frontlineworld/watch/player.html?pkg=404_peru&seg=1&mod=0

Montesinos's Web, details corruption in print and videos.
http://www.pbs.org/frontlineworld/stories/peru404/web.html



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JackRiddler Mar 2013 #21
LineNew Reply Some facts I recently dug up about gold mining...
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