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Cyanide in the rivers and groundwater of El Salvador. And water soluble aurocyanide metallic complex ions.

Where there is gold mining there is cyanide:

Gold Cyanide Solution
(Leaching Gold With Cyanide)

Since the 1890's, cyanide has been used to recover gold from gold bearing ores. And today, over 115 years later, most of the worlds gold is recovered with cyanide playing a large part in the beneficiation of the yellow precious metal. Chemically, it is a rather simple reaction:
4 Au + 8(NaCN) +O2 + 2 H2O = 4 NaAu(CN)2 + 4 NaOH

That presumes that the only elements are the gold, Sodium Cyanide and water. However, as any geologist will tell you, no two ores are the same, and their chemical composition will vary greatly throughout the ore body. These "extra" elements in the mineral compounds will often play havoc with a chemical reaction, as illustrated above.

August 3, 2010
Pac Rim CAFTA Challenge of Salvadoran Environmental, Mining Safety Policies Given Go-Ahead by Tribunal
Initial Win for Corporation in Trade Agreement Attack on Environmental Policy Poses Complications for Obama Administration as It Tries to Revive Korea FTA

WASHINGTON, D.C. – An international tribunal’s decision to allow a controversial suit against El Salvador under the 2005 Central America Free Trade Agreement (CAFTA) will fuel demands by many in Congress that the Obama administration alter the foreign investor terms in three North American Free Trade Agreement (NAFTA)-style trade pacts inherited from the George W. Bush administration and new pacts under negotiation, Public Citizen said today.

Reading the fine print in CAFTA:

The case is being prosecuted under extremely controversial CAFTA provisions that grant foreign investors expansive new rights to sue governments in foreign tribunals over regulations or government actions that conflict with the pacts’ special rights for foreign investors and that could undermine their future expected profits. These terms are included in all three of the Bush-signed but unapproved trade agreements with Panama, Colombia and Korea that the Obama administration inherited.

Hmmm, the "special rights" for foreign investors...

The aggrieved suing party is Pacific Rim Mining Corporation, Canadian-based multinational firm, which would like to establish a massive gold mine with cyanide ore processing in the basin of El Salvador’s largest river, Rio Lempa. The people of El Salvador had concerns about the mine's health and environmental implications, and rightfully so. Despite this, Pacific Rim never completed the feasibility study necessary to obtain an operating permit for the "El Dorado" project. A subsidiary of Pacific Rim, based in the Cayman Islands (where else?), was incorporated in December of 2007, to be reincorporated in Nevada under the name Pac Rim Cayman LLC (where else?). The sole purpose of this newly cloned corporate entity was apparent four months later when it sent a letter to the Salvadoran government threatening a CAFTA claim.

The fait accompli:

In July 2008, the firm ceased exploratory drilling at El Dorado. In December 2008, the firm formally launched a CAFTA claim.

Sadly, gold prices are soaring and El Salvador has been besieged with the filing of 29 permits for new mines.

For more info check out:

As noted above, when one stirs up a broth of 4 Au + 8(NaCN) +O2 + 2 H2O = 4 NaAu(CN)2 + 4 NaOH there are many notable permutations:

Copper is definitely worth mentioning, since copper minerals will dissolve in cyanide solutions, and cause a increased use of cyanide, the copper-cyanide complexes formed by the dissolution will tend to inhibit the dissolution of gold in the cyanide solution. Zinc, the element used to precipitate gold from solution, if present in the ore, will bond with the cyanide to form a zinc cyanide compound. Another element that plays with the cyanide chemistry is nickel. Nickel, however does not interfere with the gold going into solution, but rather the precipitation of the gold from the cyanide solution.

Arsenic and antimony do present a larger problem, by reacting with the cyanide and using up all of the excess oxygen, leaving little or no oxygen to effect the dissolution of gold. Carbonaceous gold ores can have the carbon adsorb the gold onto its surface, and as a result will not be recovered from the pregnant solution.

Leaching gold from sulfide ores is difficult, at best. Generally, the recovery for cyanide leaching of sulfide or refractory ores is no better than 30%, which is not a worthwhile venture.

The use of alkalies such as calcium oxide, will prevent the decomposition of cyanide in solution to form hydrogen cyanide gas. It reduces the volume of cyanide required to leach the gold or silver. In addition, hydrogen cyanide is highly toxic to people. So, the few dollars spent on adding a cheap calcium oxide to the ore or solution, prior to leaching is worth the money spent. Most cyanide leaching is carried out at a alkaline pH of between 10 and 11, depending upon lab testing of individual ores and the optimum leaching/chemical use rates.

Lovely to contemplate, is it not? I am especially moved by the interplay of cyanide, arsenic and antimony, all notable toxins.

Originally posted to Karen Hedwig Backman on Sat Sep 04, 2010 at 10:11 AM PDT.

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Comment Preferences

  •  Cortez and Pizarro live (2+ / 0-)
    Recommended by:
    Unique Material, loblolly

    in corporate perpetuity.

    American business is about maximizing shareholder value. You basically don't want workers. ~Allen Sinai

    by ActivistGuy on Sat Sep 04, 2010 at 10:34:52 AM PDT

  •  They use the same approach to extract (2+ / 0-)
    Recommended by:
    Unique Material, nzanne

    precious (and not so precious) metals from used consumer electronic products in China . . . .with approximately the same effects on the workers involved.

    It's not quite as satisfying to mention that however, because it's difficult to work in a Canada-bashing angle . . . .

  •  Its used because its cheap and easy (1+ / 0-)
    Recommended by:
    Unique Material

    There's also the point that NaCN (sodium cyanide) is going to react preferentially based on electrochemical properties. Au (gold) is preferred over many other atoms so the reaction has been long used to successfully purify gold ore. Adjusting the pH will also shift what the NaCN molecule will prefer to react with.
    It's also cheap and a fairly easy reaction to control (pH stays high- basic). Alternatives are not cheap or so easy to use. I do not know them off the top of my head, it's been many years since that discussion (& a exploration on alternatives to analyze trace metals in water/soil.) Alas, I was being a sounding board, not directly involved because it was very interesting.

    The chemist in me has fits of joy thinking through the electrochemical dynamics and interplay with other potential contaminates. The environmentalist, naturalist and social justice seeker in me just desperately wishes there was a less poisonous, polluting and economically feasible alternative.

    I just wanted to vote in the primaries. Honestly, I am much too liberal to be a Democrat.

    by WiseFerret on Sat Sep 04, 2010 at 11:17:20 AM PDT

  •  Forgotten El Salvador (5+ / 0-)

    Thank you for posting this important diary. Tiny  El Salvador has been all but forgotten since the Civil War ended.

    Former Peace Corps Volunteer in El Salvador here. I was in El Salvador before the Civil War. The rivers were where the campesinos bathed and washed clothes. Back then it was water- bourne parasites and bacteria in the water that was the main threat, and the country was owned by 14 wealthy Salvadoran families. Now apparently it is multi-national corporations dumping  toxic cyanide compounds in the water.  

    Good thing we've still got politics in Texas -- finest form of free entertainment ever invented.- Molly Ivins

    by loblolly on Sat Sep 04, 2010 at 11:29:25 AM PDT

  •  Barrick Gold,..... CAFTA,....Bush 41,..Bush 43 (0+ / 0-)

    NOP - pronounced nope. The NOP party. The NO Party = NOP. BTW, Boner from Ohio still sucks.

    by 0hio on Sat Sep 04, 2010 at 04:56:48 PM PDT

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