How is value extracted from a hard rock mine?

C

Capricorn

Jr. Member
May 21, 2013
66
34
Oregon
Primary Interest:
Prospecting
I'm curious about how miners capitalize on the values in their mines. I'm guessing it really depends on the types of deposits? Free milling gold makes sense to me, crush, mill and seperate. Leaching makes sense to me, crush, mill, leach, recover... But what about other mineral deposits? I stumbled across info for this mine for sale:

https://bonanzaclaims.github.io/SunsetMineClaim/​

The video was pretty neat. Anyway it got me thinking, how would people actually extract zinc or copper or some other mineral? I suppose each has its own process. Would folks mostly be hauling ore to some other plant somewhere and just letting them extract it? Are there many places like that in the US these days? Just a bit curious and thought folks here might be knowledgeable. Thanks! :)
 

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There is no value there. The assay reports show that efforts to mine the higrade that was assayed would result in a loss.

There is some value in the fact that if you purchased the claim you would have several active acid mine drains in Oregon. That's clearly illustrated in the pictures and video. Of course that would be a negative value when you are presented with the bill for clean up.

Zinc and copper are only profitable to mine when the deposit is large, the time horizon is long and the owner has the kind of resources needed to build and maintain a purpose made processing facility. You aren't going to find that on eBay.

Heavy Pans
 

Clay Diggins said:
There is no value there. The assay reports show that efforts to mine the higrade that was assayed would result in a loss.

There is some value in the fact that if you purchased the claim you would have several active acid mine drains in Oregon. That's clearly illustrated in the pictures and video. Of course that would be a negative value when you are presented with the bill for clean up.

Zinc and copper are only profitable to mine when the deposit is large, the time horizon is long and the owner has the kind of resources needed to build and maintain a purpose made processing facility. You aren't going to find that on eBay.

Heavy Pans
Click to expand...

I have no interest in purchasing it. I was more just curious about how minerals other than gold would be extracted and processed. It sounds like economically it makes sense to build special processing facilities on sight, as opposed to say shipping and selling ore to some pre-existing facility somewhere? What did you mean by acid mine drains? Just that moisture in the mines would likely be acidic?
 

I get a “404 file not found” when I click the link.

Historically, there are over 100 mines called “sunset”, and over 80 called “bonanza” in Oregon. Since the link is not accessible to me, I can not comment, except to say “RUN!”.

As to how different ores are processed, I would suggest perusing the many professional miners forums, plus looking at the websites of mining companies. The subject is far too long and complex for my stroke addled brain to explain most processes without screwing something up.

Time for more coffee.
 

Thanks, Clay. I am familiar with several mines in that area, including the Sunset. Most, including this mine, will need far more remediation than most can afford. It was offered to me a few decades ago. I turned it down. Even had I been prepared to do something with it, the regulatory environment in Oregon, even then, was far to onerous for most small timers to make wages. Today, it is more so.

As to processing ore from the area, the ores in most Bohemia area mines have a complex of both free milling and sulfide ores. This is where the problem lies. Natural groundwater, when it comes in prolonged contact with the sulfides, will form a weak sulfuric acid. If on the Willamette side, it becomes part of the drinking water for Cottage Grove. On the North Umpqua side, it becomes a problem for Roseburg. For the moment, dilution takes care of many of the problems caused by acidic water draining from area mines.

The last time I visited the area, which was about a decade ago, the upper reaches of many creeks, especially those that had a tributary directly from a mine, had ample evidence of acidic water.

There are are ways to mine and process ores of that area, causing minimal, short term, environmental problems. The State of Oregon, however, and many downstream residents of the area, do not want to deal with mining impacts. Hence, the regulatory burden imposed by various agencies of the State of Oregon.

Time for more coffee.
 

Thanks guys for your feedback, it's appreciated. And for sure I have no interest in that particular mine, it just got me thinking.
 

In general, the topic of metal extraction, metallurgy is to wide to cover in a single thread let alone post. Besides that there's lots of chemistry and what not.

There are though several general methods you could look into, a few examples:
Heap Leaching,
Flotation,
Gravity concentration,
Magnetic separation (as in iron ore - magnetite)
 

Just to add to this subject, keep in mind that some small-scale miners like myself, also make good money on selling specimens. Crushing and extraction is good with volume obviously, but I have to say that the specimen business does very well. For example the below pieces:

IMG_0209.jpg

IMG_0196.jpg

IMG_0192.jpg
 

yep specimins are where its at for small scale hard rock
 

Thanks Anna! What are the specimens of in your first and third picture?
 

Goldwasher said:
yep specimins are where its at for small scale hard rock
Click to expand...
The shot I took of these fellas driving a drift are solely mining for mineral specimens. They asked me to come up and see why they're busting so much drill rod. From what I gather, they'll be driving this drift parallel to a large slip in the mountain that has the rhodochrosite crystal specimens they hope to find. Then they drill a 3-1/2" hole into the rib and inspect the voids they encounter with a camera. If they get lucky and find a large void with crystals growing within it, they then excavate it very carefully so not to destroy the crystal specimens.They get a lot of money for the more primo specimens.
 

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Capricorn said:
Thanks Anna! What are the specimens of in your first and third picture?
Click to expand...

First one is copper and Azurite and some free milling gold present.

Third one is interesting...that’s actually an extremely rare mineral called “Coloradoite” - basically the solid form of mercury. It’s also mixed with gold and silver.
 

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The gem show in Tucson is one of, if not the largest and various vendors set up sales booths or sell out of motel/hotel rooms for at least two weeks previous to the main show. 2018-2019 Tucson Gem Shows Schedule
 

AnnaMountain said:
First one is copper and Azurite and some free milling gold present.

Third one is interesting...that’s actually an extremely rare mineral called “Coloradoite” - basically the solid form of mercury. It’s also mixed with gold and silver.
Click to expand...

Could you grind up some of that stuff, put in a closed test tube heat and show the metallic Hg.
Would be a neat science experiment.

Mercuric telluride, nice ore specimen.
Thanks for sharing.

Gt......
 

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Capricorn said:
I'm curious about how miners capitalize on the values in their mines. I'm guessing it really depends on the types of deposits? Free milling gold makes sense to me, crush, mill and seperate. Leaching makes sense to me, crush, mill, leach, recover... But what about other mineral deposits? I stumbled across info for this mine for sale:

https://bonanzaclaims.github.io/SunsetMineClaim/​

The video was pretty neat. Anyway it got me thinking, how would people actually extract zinc or copper or some other mineral? I suppose each has its own process. Would folks mostly be hauling ore to some other plant somewhere and just letting them extract it? Are there many places like that in the US these days? Just a bit curious and thought folks here might be knowledgeable. Thanks! :)
Click to expand...

You have free mill and leaching confused. They're the same. Free milling gold is the gold that can be recovered through cyanide or other types of chemical leaching. What you're thinking of is macroscopic gravity recoverable gold as a fraction of the free mill.

And industrial metals are useless to the small scale miner. Small scale miners work in the range of up to a few tons per day. The economics of industrial metals depends on fully processing multiple tons per minute.
 

I can't get the link to open on this computer. There's also money in mine tours. We went on one a couple weeks ago, $25 a person for an hour tour and there were 12 people on our tour. Pretty sure there was more money in mining the tourists than trying to get the mine permitted.

Industrial metals have big potential but it seems most copper, zinc, moly, ect. mines owners are into them well over 100 million before they process a rock.
 

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