Mining Economics

[geonuc]

Last week I was in Montana on vacation and visited the Benbow Mine, located in the Stillwater Range just west of Red Lodge. It's abandoned but apparently sits on a goodly portion of the USA's chromite reserves.

Now, chromite is a pretty useful ore, what with chromium being a key constituent of many metal alloys. Yet, the operational history of this mine is quite limited - mainly during wartime.

I find this puzzling. Yes, I know it's all about economics and the price of rice in China, but still. I did note that the mine was very recently sold, so maybe the economics are shifting.

By the way, the road to the mine is gorgeous and a geologist's delight. I have many photos and I, ummm, borrowed a few rocks. :shifty:

[Ronald Brak]

The chromium in this mine may simply be more expensive to extract than deposits in South Africa and other places. But a lot of commodites have gone up in price so it may be economical to mine there now.

[Ivan Viehoff]

Or maybe they were poisoning the place and environmental restrictions placed on them made it too costly to continue. See Jared Diamond's book "Collapse" in relation to the very costly clean-up of pollution caused by gold mines in Montana.

[NEOWatcher]

I don't know how the rest of the industry works, but one of the big players in the Great Lakes area has been working on realignment over the past few years. It may be anecdotal, but I would guess that they aren't the only ones.
They have been selling off thier transportation interests and buying into other mining interests. A low yield mine might get a new life as it changes hands from a company that might not have enough resources to exploit them.

[Nick Theodorakis]

Often times the mining industry makes the oil industry look like Greenpeace.

Nick

[geonuc]

Hard to say just from a casual visit to the site, but I don't think there were major environmental issues at Benbow.

[galacsi]

Hard to say just from a casual visit to the site, but I don't think there were major environmental issues at Benbow.

Yes its very difficult to know without chemical analysis. Chromium can be very dangerous .(Hexavalent chromium is recognized as a human carcinogen via inhalation. )

[Ivan Viehoff]

Just had a quick look at our favourite source. Seems there is a lot of high grade chromite available in places with cheap labour, especially southern Africa, India and Kazakhstan, and the location of large, as yet untapped, deposits in the same regions is known.

So I guess they mined it in the war because of difficulties with supply lines, but it quickly became uncompetitive afterwards.

[sabianq]

I thought this post was about "Mining for Data"

LOL

[geonuc]

As I was aware of the history of Benbow mine and the world-wide distribution of chromium deposits, I guess the real reason I posted was more rhetorical. I find it somewhat mind-boggling that global economics makes it profitable to ship ore halfway across the world rather than dig it up in your own backyard. The same situation occurs with many products, of course.

[sabianq]

with the cost of energy and fuel going up these days, that Paradigm is shifting.

but the reason for the price difference in mineral extraction is multi fold. here in the US say The cost of labor, (there are laws that say you cant make someone work for slave wages), you need to have insurance, you need to have safety inspection, EPA regulation, you need all sorts of extra stuff that costs money., in a different local where the laws are somewhat lax or even nonexistence, it can be very inexpensive to refine material, so the associated costs of extraction is the sum of all expenses.

you can see how it can be expensive to mine here in the states where regulation can be a economic hindrance.

[Ivan Viehoff]

Hexavalent chromium is recognized as a human carcinogen via inhalation.
I think that is mainly because it is a powerful oxidising agent. Hexavalent chromium is so reactive that it only comes out of factories, not the ground. Stable oxidation states of chromium are not normally poisonous.

One question is whether, (like with gold), they do large-scale poisonous outdoor chemical extraction on the ground at the site of the mine, that risks environmental escape, or (like with aluminium and iron ore) just send the rocks off to a refinery to be processed. Another question is whether there is anything else (nothing to do with chromium) in the rocks in the spoil heap that can wash off and make a nuisance of itself.

[peteshimmon]

Not mining but gold panning. I have wondered
if an automatic river panner has ever been
tried. Sort of an upturned boat with paddle
wheels powering the internal works that scoops
up the river bed. Then moves itself along.
The minder sits in a deckchair with his hat
down chewing some grass!

[Ronald Brak]

I find it somewhat mind-boggling that global economics makes it profitable to ship ore halfway across the world rather than dig it up in your own backyard. The same situation occurs with many products, of course.

Ocean transport is very cheap when done in bulk. Dollars per ton. But oil price rises over the last few years have significantly increased the cost.

[teddyv]

Haven't been around here for a while, but found a thread I migh actually be useful in.

One question is whether, (like with gold), they do large-scale poisonous outdoor chemical extraction on the ground at the site of the mine, that risks environmental escape, or (like with aluminium and iron ore) just send the rocks off to a refinery to be processed.

Most metal mines will produce a concentrate on site and then ship to a smelter for recovery of the various metals. Concentration would use different techniques that would offer the best recovery of the metals - this is all determined prior to commencement of mining. Methods include cyanidation, bioleaching, heap leaching and others. We are currently working on a copper project with a typical ore grade around 0.3% Cu. After concentration the grade should be close to 30%.

Ore mined from a pit or underground is generally not dangerous - except perhaps uranium. Gold ores are often associated with arsenic bearing minerals, however its generally stable.

Another question is whether there is anything else (nothing to do with chromium) in the rocks in the spoil heap that can wash off and make a nuisance of itself.

It's called Acid Rock Drainage (ARD) and it is a problem. Most metals in hard rck mines are sulfides (like pyrite). Depending on the concentrations and climate, suddenly exposing tonnes of this material to the atmosphere can result in fairly acidic runoff over time.

[teddyv]

Not mining but gold panning. I have wondered
if an automatic river panner has ever been
tried. Sort of an upturned boat with paddle
wheels powering the internal works that scoops
up the river bed. Then moves itself along.
The minder sits in a deckchair with his hat
down chewing some grass!

That would be a dredge.
http://www.yukoninfo.com/dawson/info/dredgetailings.htm

[Ivan Viehoff]

Most metal mines will produce a concentrate on site and then ship to a smelter for recovery of the various metals. Concentration would use different techniques that would offer the best recovery of the metals - this is all determined prior to commencement of mining. Methods include cyanidation, bioleaching, heap leaching and others. We are currently working on a copper project with a typical ore grade around 0.3% Cu. After concentration the grade should be close to 30%.
Always excellent to get this from the horse's mouth, as it were. As I understand it, substantial high grade chromite deposits (60% even 90%) are available for mining. Since chromite is (Fe,Mg)Cr204 so rather high in chromium, perhaps they don't need to do any chemical concentration before shipping it out. My understanding is that aluminium and iron ores are also generally just shipped out as rock without any chemical concentration.

[geonuc]

Always excellent to get this from the horse's mouth, as it were. As I understand it, substantial high grade chromite deposits (60% even 90%) are available for mining. Since chromite is (Fe,Mg)Cr204 so rather high in chromium, perhaps they don't need to do any chemical concentration before shipping it out. My understanding is that aluminium and iron ores are also generally just shipped out as rock without any chemical concentration.
I need to look into the operation of the Benbow chromite mine a little more, I think, just to satisfy my curiosity about a place I've twice gone to the trouble of visiting. But I do know they transported the ore off the mountain to a mill site below. The mill site is almost completely gone, with only bare concrete structures remaining. I couldn't tell what sort of process went on when it was operating.

One thing's certain - if there was any environmental damage from the operation, it is entirely invisible right now. The area is wonderful and visiting the mine site is a bit like visiting a ghost town of the old west.

I recently paid for a subscription to flickr ('geonuc', of course) and plan to upload a lot of pictures, including those taken at Benbow.

[geonuc]

If anyone is interested in the mine site and the geology of the Stillwater area, this GSA publication describes it pretty well and is what originally led me there:

http://www.gsajournals.org/archive/0-8137-5402-X/2/0/pdf/i0-8137-5402-X-2-0-69.pdf

[chrissy]

geonuc, there seems to be an URL error on this link!

Your pictures are great by the way, thanks again. :)

[geonuc]

I just clicked on the URL and it pulled up the pdf. Not sure why it didn't work for you.

Thanks.:)

[Neverfly]

I just clicked on the URL and it pulled up the pdf. Not sure why it didn't work for you.

Thanks.:)

It's not working for me either. I didn't say anything because I figured you would correct it...

How odd...
This attachment shows exactly what I'm seeing when I click your link:
8382

[NEOWatcher]

I just clicked on the URL and it pulled up the pdf. Not sure why it didn't work for you.
Not me, either.
Perhaps if you give us title and author or other identifying information we can perform a search and see how it routes us to it.

Maybe there's some subscription issue that keeps us out of certain areas, or some cookie issue, or some other issue related to previous visits.

[geonuc]

Hmmm, wierd.

Anyhoo, Google:

"stillwater GSA centennial"

It's the second hit, which is a subhit of the first hit.

[Neverfly]

http://www.gsajournals.org/perlserv/?request=get-abstract&doi=10.1130%2F0-8137-5402-X.69
The google hit

http://www.gsajournals.org/archive/0-8137-5402-X/2/0/pdf/i0-8137-5402-X-2-0-69.pdf
Geonucs link

For comparison...?

[geonuc]

Yeah, the Google link takes you to the page where their pdf link resides. But that pdf link still works on my computer.

Maybe someone smarter than me can explain that.

[Neverfly]

Maybe someone smarter than me can explain that.

No, I really can't...

[NEOWatcher]

Maybe someone smarter than me can explain that.
Will educated guesses be accepted?

The link works fine for me now. Something is requiring you to visit that parent page first (or some other part of the site). So; cookies are suspected.
I also suspected a session variable, but I closed out of my previous sessions before trying.

[HenrikOlsen]

Sounds like a site with hot-linking protection.

[peteshimmon]

Thanks for that teddyv, your link worked fine.
I was thinking of a smaller device for British
rivers which would walk upstream over a few
hours automatically scooping and panning the
riverbed. Perhaps more for sampling yet able
to produce a cheerful amount of the stuff if
it is there. Gold being what it is I am sure
some have thought of such a thing.

[teddyv]

Always excellent to get this from the horse's mouth, as it were. As I understand it, substantial high grade chromite deposits (60% even 90%) are available for mining. Since chromite is (Fe,Mg)Cr204 so rather high in chromium, perhaps they don't need to do any chemical concentration before shipping it out. My understanding is that aluminium and iron ores are also generally just shipped out as rock without any chemical concentration.

I am not overly familiar with chromite deposits - I deal mostly with gold and copper deposits. As I think mentioned by someone else previously, most Cr is mined from South Africa (Merensky Reef) and (another guess) from beach sands. As it is an oxide, refining to pure Cr would probably need a similar smelting process as Al or Fe. So yes they would ship it to some location with lots of cheap electrical power.

Iron is concentrated before smelting. I don't have the numbers offhand of what the typical ore grade is in the US open pit iron ranges. Aluminum ore (bauxite) is basically pure Al2O3 so it needs little concentrating if any at all.

[teddyv]

Thanks for that teddyv, your link worked fine.
I was thinking of a smaller device for British
rivers which would walk upstream over a few
hours automatically scooping and panning the
riverbed. Perhaps more for sampling yet able
to produce a cheerful amount of the stuff if
it is there. Gold being what it is I am sure
some have thought of such a thing.

Better check your placer mining regulations for operating a mini-dredge :). Dredges completely tear up and destroy rivers.

Placer mining on a slightly larger scale than using a pan typically involves a back hoe loader and a sluice box.

[teddyv]

I need to look into the operation of the Benbow chromite mine a little more, I think, just to satisfy my curiosity about a place I've twice gone to the trouble of visiting. But I do know they transported the ore off the mountain to a mill site below. The mill site is almost completely gone, with only bare concrete structures remaining. I couldn't tell what sort of process went on when it was operating.

One thing's certain - if there was any environmental damage from the operation, it is entirely invisible right now. The area is wonderful and visiting the mine site is a bit like visiting a ghost town of the old west.

I recently paid for a subscription to flickr ('geonuc', of course) and plan to upload a lot of pictures, including those taken at Benbow.

Geonuc - I tried looking for info on the Benbow Mine but couldn't find out whether it was an underground or open-pit. Google maps suggests an underground operation (no obvious pit) and that would make sense based on the limited knowledge I have of the Stillwater complex. It would explain why there is little environmental degadation as well.

[geonuc]

It is an underground mine. At the top, there is some evidence of digging into the mountain on the surface and there's a lot of bronzite (I think) rock laying about, but I saw no chromite ore on the surface.

At least at the mine itself. As indicated on the GSA field trip paper I clumsily linked to, there is a small outcrop of rock a short distance down the road which contains visible chromite. Looks like red paint on the rock.

[Trebuchet]

I think I may have visited that mine, or at least the associated mill, when I was a child, probably at least 50 years ago. The name was different, however -- I remember that it was the Mowatt mine or something of the sort. Certainly it was in the same area, perhaps there was more than one. My Dad was a salesman and making a call on the mine office, and took me with him. We got to go inside the mill, which I remember as having lots of huge scary machinery. There was some sort of sorting system involving water and crushed rock material flowing over sort of tables, working its way down slope. The ore was sort of shiny black.

There was also a really depressing looking company town there. All gone now, I expect.

[geonuc]

That would be the Mouat mine, I believe. I intended to visit it, as well, but didn't manage to fit it into my schedule. It's just to the west of Benbow, although I think it's not so high up in the mountain.

Yes, the ore rock is quite black and shiny.

A history of the area:

http://www.stillwaterpalladium.com/stillwater.html

[Trebuchet]

Yes, a little googling this morning led me to the Mouat Mine. It must have been in the late 1950's that I was there. The mine closed around 1961.

[geonuc]

For those interested: photos of the Benbow Mine area.

http://www.flickr.com/photos/49925617@N00/sets/72157606369324436/

I've just activated the flickr account. Hope the link works.