Talk to me about cyanide leach mining

Factual Questions
1

Cyanide leach processing is currently a hot topic in Montana. For those who don’t know, it’s a process used in mining gold, which uses cyanide. At present, it’s banned in Montana due to environmental concerns, but there’s a issue on the ballot to change that.

The sponsors of the bill (mining companies, of course) claim that the environmental regulations set forth are adequate, and further point out that since cyanide is neither a carcinogen nor a bioaccumulant, there is a threshhold level of cyanide contamination which would be perfectly safe. From what I know of biochemistry, this is correct, however, there are a number of critical points I don’t know:

First, just what exactly is a safe environmental level of cyanide? It’s produced by many plants, so surely there’s a natural background level. How high above that background would be safe?

Second, just how much cyanide is used in a gold-mining operation? How much of that cyanide could be released into the environment, with what distribution, in a worst-case catastrophe? What about in a less than pessimal case?

Third, are there any available methods to clean up such environmental contamination, and what would be the monetary costs of such methods, in various failure scenarios?

Fourth, what measures can be taken in the design and construction of the facility to decrease the likelihood and severity of contamination events? Have there been any contamination events from such processing elsewhere, and if so, what safeguards were present at those facilities?

Please note that although this question is politically motivated, this thread is not the place to discuss the politics of the issue. I’d just like the factual information, please.

2

It appears from the WATER RESOURCES MANAGEMENT PLAN from Salinas Pueblo Missions National Monument (can we assume that acceptable levels are pretty much the same everywhere?) that a safe level of cyanide in water is 1400 Million Fibers/liter.

I find it disconcerting that the CDC reports that Cyanide is a potential chemical agent to be used by terrorists and that a Google search for “cyanide” provides links to buy it on ebay. You can probably get it anywhere I suppose.

Google News shows a few articles on the topic and it seems that the state of Montana has done some investigations into the topic which are most likely publicly available. I don’t have time to dig but I see a bit of promising stuff here. Lastly, I have been successful in the past with e-mailing the journalist who has written some of these small-town articles in Google News for further leads.

3

My math was incorrect on that fibers/liter. Just do a text search for “cyanide” in that article. First result.

4

IANA Aquatic Ecologist, oh wait, I am! Will you look at that? Actually, I used to be one, back when I was still doing research & fieldwork. Now I just do project management but still, I’m still in watershed management.

Anyway, after a bit of googling so I know what’s going on in Montana, I think the key part to your question is here:

This is key because the opponents to the measure report that the Director of the DEQ has publicly stated that I-147 does not introduce any real new regulations; in reality it just repeals the measure that passed banning open pit mining with cyanide. So if in the past, the regulations were inadequate to protect human health & the environment (examples were listed the linked page), then I-147 will be just as inadequate.

As to clean up costs, the linked page above says that taxpayers could be paying millions, (up to 40 million) for clean up costs for 3 of the mines, mines that “employed the very measures that are in I-147 and which cyanide-leach proponents claim are “new”.”

So that’s the other angle you might want to look at, not just whether the leached cyanide would reach the threshold level or safe level or Total Maximum Daily Load for a certain waterbody, but whether the previous/existing regulations have been adequate.

Looking at the DEQ and USEPA websites, I see that Montana has not completed a Cyanide TMDL (Total Maximum Daily Load) for the Blackfoot, even though it’s probably an impaired waterbody. <sigh> That’s where I was looking to give you an answer to your first question.

See, you can’t just look at what’s “safe” for a river in/near Salinas and assume that would be “safe” for the receiving waters near the Montana mines. Sure there’s a certain threshold for cyanide toxicity for humans, and another for certain fish, and another one for pregnant women or so forth. But the real question is, what is the maximum amount of contaminant that a particular water body can receive without harming any of its designated uses (i.e., swimming, fishing, drinking, as habitat for fish or the other critters, etc.). This is because there are many factors that could differ from one waterbody to the next, such as: contaminant fate transport, chemical mechanisms that make the contaminant more or less toxic (e.g. methylation of mercury makes it more toxic), how quickly the contaminant is diluted due to flow or how slowly it settles into the sediment, etc.

Anyway that’s why States are mandated to do TMDLs for specific waterbodies, and Montana is still collecting the data to determine the TMDL for cyanide for the Blackfoot. Since TMDLs could take years, more than a decade sometimes, I don’t know if anyone can say they know I-147 will adequately protect the public or the environment, since the TMDL hasn’t been established there.

So…bottom line, if you voted Yes on I-137 before, or think the ban was a good idea, then use the same judgement for I-147.

5

Wow! I just noticed I answered a question for someone on the frickin’ SDSAB. I don’t know whether to frantically check my facts and look for more cites, or look for a bigger hat for my swelling head. :wink: :smiley:

6

Fibers? That’s asbestos. The figure for cyanide is 200 micrograms per liter, or 200 ppb. And no, it can’t be used for a different body of water, as Aragowyn pointed out

7

It’s unambiguous that I-147 does not tighten regulations in any way; “allowed under the following conditions” is certainly more permissive than “not allowed”. But it’s still possible, given that, that the previous regulations (i.e., “not allowed”) might have been tighter than necessary, in which case a loosening might be justified.

However, reading further,

If I’m reading that correctly, the relevant data to make an informed decision for I-147 does not yet exist, and we cannot yet know what represents a safe level of cyanide in Montana’s waters. Am I understanding this correctly?

8

I tried searching further for where they are in the process for a TMDL for cyanide on the Blackfoot or its creeks, or if they even consider it impaired for cyanide, and didn’t find out anything for you (and wow is the DEQ server slow!). So without a TMDL, you’re right, you can’t know what a safe level of cyanide is in the receiving waters of the potential mines.

However, I wouldn’t decide my vote on the basis of knowing what a “safe” level of cyanide is. Because even if there was a TMDL for cyanide for the waterbodies that you know will be downstream of a proposed open pit mine, and even if you had confidence that the enforcement (for water quality monitoring & mandated actions to prevent contamination) will be judicious on said mine, how do you know that pre I-137, the regulations were adequate? The fact that there are clean up efforts (on what was it, 3 mines?) points to the possibility that they weren’t adequate.

And if I-147 returns things to the way they were before, to regulations that weren’t adequate, well there you go.

9

IANA miner, but my dad designs 'em for a living.

If a mine is designed and built properly, using cyanide is pretty damn safe (and any design, like the ones my dad makes, should include a number of redundant steps). After all, people are walking around and using, and recycling, the cyanide, so you want to make sure they’re not dropping dead because of some easily avoidable error.

You also want to make sure that if there is an accidental leak that containment measures are in place-- redundant dikes and levees to make sure cyanide doesn’t spill into a nearby stream and wipe out 4000 fish. Incorporating those designs is fairly simple, even if implementing them may be expensive – but there’s a reason why gold sells for $$$.

That being said, there are places where companies try to take shortcuts. My dad went to troubleshoot one mine in Africa where a hopper on a platform was shaking uncontrollably every time it was turned on. Turned out the platform was made with half-inch hollow aluminum piping that dad bent in half with his bare hands; the specs called for 2" solid steel.