ScholarDay has been writing recently of a proposed open pit cyanide heap leach mine proposed in the Centennial Mountains in Eastern Idaho: the Kilgore Project.

We’ve talked about how the Centennial Mountains are the only remaining wildlife corridor connecting large mammal populations (including grizzly bears) in Yellowstone National Park to populations in central Idaho and northern Montana. We’ve given a timeline of the failed efforts at mining in the Kilgore area, as well as a chronology of Otis Gold’s current efforts. We’ve made some general (and hopefully desperate) pleas to members of the general population to voice their concern over the mining project.

This post will provide some general information about the meat-and-potatoes of the Kilgore Project. Namely, the meat-and-potatoes that is open-pits-and-cyanide.

Bullet Points

Open pit cyanide heap leach mines consist of pulverizing tremendous amounts of ore, and dripping cyanide dilute over them to dissolve the gold out.

Cyanide laced tailings rest in perpetuity behind enormous earthen tailings dams.

Many of these dams have failed in the last decades, causing various cases of ‘worst environmental disaster in the history of…’

A very brief history of mining with cyanide

The process whereby gold dissolves in cyanide was discovered in Scotland in the 18th century. In 1891, Mercur, Utah became the first mine to successfully use the cyanide process of gold extraction in the United States. This process was made economically feasible by a Nebraska investor, Gilbert S. Peyton, who had been duped into buying an unfeasible claim. Peyton didn’t want to lose money on his investment. 

And as for many people in dire straits, cyanide provided an out for this desperate investor.

The basic mining process which Peyton made feasible at the Mercur mine can be found in nice animations and explications online. Gold-containing ore is mashed up into a massive heap atop an impermeable layer, and a cyanide dilute solution is dripped upon it, like baptismal water on the forehead of already-sinning infant.

Two cyanide ions bond with a gold atom, in something like a move from Red Rover, and the new molecules seep into a ‘pregnant pond.’ The pregnant pond is then treated with more chemical sophistry to reveal the pure gold extract.

More on the waste products, which don’t have the economic value or excitement of gold, later.

In the 1970’s, the value of gold skyrocketed from about $35 per troy ounce (which is 31.1035 grams) to $750 per troy ounce. Duly motivated by the Invisible Hand of Demand, which may or may not be the Invisible Hand of God Himself, the use of cyanide heap leach mining grew ever more popular and ever more efficient. The current price of gold is $1,306.60.

We’ll definitely be needing more cyanide!

Interlude: cyanide: pros and cons

I’ve never seen a cyanide molecule in real life, or even a cyanide tablet. But I have colored with the ‘cyan’ crayola. In fact, it made a perfect two inches of clear sky at the top of any artless picture I may have drawn as a child.

The invisible cyanide molecule, which consists of one innocent carbon atom triply bonded with one harmless nitrogen atom, has played a big role in this planet’s recent history.

Here’s a quick skim of cyanide’s recent non-mining timeline:

Hydrogen cyanide, released from pellets of Zyklon B, was a main killing agent in German extermination camps during the Holocaust.

Hydrogen cyanide, in liquid form (then called prussic acid) was used by many Nazi agents to commit suicide, including Himmler and Göring.

Alan Turing, who was a major player in the invention of computers, may or may not have died after ingesting a cyanide laced apple.

The revolutionary suicides of Jonestown were similarly the work of cyanide poisoning.

You can go read for yourself more about the efficient and storied history of cyanide as a killing device.

No one can say that cyanide is not good at its job!

Back to the bottom line: cost effective 

The good news about the cyanide process in mining is that it allows companies to extract gold from very low grade areas, or even from the tailings of mined-out underground gold mines. This makes cyanide pretty good at something besides killing, that is, extracting gold from formerly unprofitable mining projects. 

A mining.com article from 2015 cites the Fire Creek Mine in Nevada, USA as the highest-grade gold mine in the world, at 44.1 grams (of gold) per tonne (of ore deposits) (g/t or gpt). According to a Midas Gold presentation, their proposed project, the Stibnite mine in central Idaho, has a grade of 1.6 gpt, of which they are very proud (at least in front of the investors).

The Kilgore Project, proposed in Idaho’s Centennial Mountains, contains a drill-indicated 520,000 ounces at 0.59 gpt and an inferred 300,000 ounces at 0.46 gpt. About one small paperclip worth of gold for every obese family of six does not seem like much. But, through the heroic actions of the hero of this piece, cyanide, such puny ratios are profitable. And this, of course, is what matters. 

What can go wrong?

In a word of understatement, plenty. Most of the potential problems with mining with cyanide have to do with the waste products of the mining process (if we ignore the defacement and destruction of huge swaths of ecosystems in the first place.)

The cyanide-laced slurry is stored in perpetuity in large tailing dams. These consist of very large earthen dams or dikes which hold back the toxic waste, protecting our watersheds and the populations (read us) that depend on clean water.

And like everything that our species has made so far, at one time or another, they fail. And as you can imagine, when the failures have anything at all to do with cyanide, the failures are significant.

Here are a couple of notable cases:

Baia Mare, Romania

On January 30, 2000, a tailings dam broke and spewed cyanide-laced slurry into the Tisza River. A 40 km flow of toxic sludge destroyed all life in the river. It went on to flow 1000 km through Hungary and the Balkans, entering the Danube and poisoning drinking water supplies in three countries.

Jozsef Feiler of the Friends of Earth in Hungary said, “Everything down to bacteria is dead. There’s more life in a sewage channel than this river now. Nothing is alive. Zero.”

It has been called one of the biggest environmental disasters in European history. Some say that it is the worst since Chernobyl.

On the bright side, at the time of the disaster, Hungary was applying for protection of the Tisza River under the Ramsar Convention, a treaty which protects wetlands of international importance. Think of all the time and headaches they saved by not having to fill out all that paperwork!

Doñana National Park, Spain

On April 25, 1998, a breach in a tailings dam burst, coughing seven million tonnes of toxic sludge around the area of the Aznalcóllar mine. This surrounding area included Doñana National Park, one of Europe’s largest National Parks.

The disaster was summed up by Vicky Short in her article about clean-up efforts:

Nothing survived because of the high acidity of the waste, which contained a mixture of lead, copper, zinc, cadmium and other metals, along with sulphides.

Mount Polley, British Columbia, Canada

In what has been called the ‘largest environmental disaster in modern Canadian history,’ on August 4, 2014, a tailing dam breached and spilled 4.5 million liters of slurry into BC’s pristine Cariboo River and Quesnel Lake.

Also troubling is the apparent fact that the tailings dam was not inspected in 2010 or 2011, despite reports of cracks.

The area’s populations depended mainly on fly-fishing tourism for their economic well-being. The dam disaster effectively destroyed the local economy. To say nothing of the local wildlife populations, of course.

Some common factors

Some common causal factors appear in the analysis of these and the other tailing dam failures in the last couple decades. These commonalities are pretty frightening: small earthquakes, heavy precipitation, unknown geology below the dams, engineering mistakes, and human error.

None of these factors seem likely to cease any time soon.

It looks like there is a lot more cyanide in our rivers in the future.

Places that have banned cyanide heap leach mining

A number of countries, US states, and Argentine provinces have seen the writing on the wall and gone ahead and banned the use of cyanide in mining. These Include:

The Czech Republic (2002)

Germany (gradual reduction, 2006)

Hungary (2009, they knew from experience)

Turkey (2007)

Argentina (various provinces, between 2003 and 2008)

Costa Rica (2002, moratorium)

United States – Wisconsin (2001)

United States – Montana (1998)

Especially nice to see on this list is the Centennial Mountains’ other half, Montana. Their law banning the use of cyanide in mining, Initiative 137, was upheld by the Montana Supreme Court in Seven Up Pete Venture v. Montana. The United States Supreme Court declined to review the decision by the Montana Supreme Court, stating that such a ban does not infringe upon the property rights of the mining company.

A general observation and complaint

This whole process is reminiscent of many other problems in our society, at least from the fold-out chair where I’m sitting. When faced with the potential, or even almost certain destruction of the environment, we seem always to err on the side of profit, as it were.

It speaks to our general short-sightedness and selfishness. When faced with unknowns, such as the structural integrity of earthen dams containing millions of tons of unstable toxic slurry, or the potential impact of heavy snowfall in snow-laden places like Idaho, we rarely play it safe. We choose to continue with activities that we know are dangerous, if they are profitable.

As a society, we seem to lack the proper calculus to make complex decisions. And we have systematically displaced and destroyed those societies which, by all appearances, did have the proper priorities and understanding to survive on this continent for thousands of years. But that is a whole nother story, as they say.