Leach process for large quantity of black sands

[Platdigger]

The embrittling agents are mentioned in the patent.
The elements are in the sand they were treating
I found this patent even way before I found this forum.
Sort of started me down this path.

 

[kurtak]

goldshark - I am no expert in this field - however I have a friend that ran a fair size placer operation & one night (over a few glasses of whiskey) talked about black sands

From our whiskey clouded talk a couple things I remember



milling the black sands to much finer mesh freed up more gold - by a lot



& if I remember right flotation used for ultra fine recovery

I will try to get with him & pick his brain more - may take a few days

Kurt

As an update to my above post I talked to my friend again

He has a couple tons of black sands

He took "random" samples (about 32 samples of about 1 oz each) mixed well together (so about 2 pounds)

Divided that into two 1 pound samples

Milled 1 pound to 150 minus mesh

Milled the other 1 pound to 300 minus mesh

Sent the two samples in for assay

The assay on the 150 mesh came back at 7 ozt/ton

The assay on the 300 mesh came back at 17 ozt/ton

The point being that milling frees up more gold - by a lot

He has not actually processed his black sands as he sees them as money in the bank - so don't know actual best method for actual recovery from sands milled that fine would be

Knowing that "fine" gold can be encrusted in the matrix of the iron oxide he simply wanted to see how much more gold could be freed up by milling

Black sands - like ore - are going to vary - by a lot - depending on location etc. etc.

For what it is worth

Kurt

 

[finargle]

A lurker from Australia. Just to show you how rich black sands can be, I saw an assay from one of our Mines Departments where a sample ran 103 ounces to the cubic metre of black sands. Unfortunately our mining regulations have blocked access to the bonanza. The report didn`t state what assay methods were used. I haven`t found any other assays of BS across Oz, so it might be a one-off. One of our geo gurus, Allan Wilson (now deceased), wrote an interesting article which I posted on Doc`s old forum about the creation of auriferous solutions in iron-infested country which led to deposition in swamps of nuggets that grew to impressive sizes. Might this be how gold was deposited within black sands? I can post it here if you`d like a copy.

 

[Alondro]

A lurker from Australia. Just to show you how rich black sands can be, I saw an assay from one of our Mines Departments where a sample ran 103 ounces to the cubic metre of black sands. Unfortunately our mining regulations have blocked access to the bonanza. The report didn`t state what assay methods were used. I haven`t found any other assays of BS across Oz, so it might be a one-off. One of our geo gurus, Allan Wilson (now deceased), wrote an interesting article which I posted on Doc`s old forum about the creation of auriferous solutions in iron-infested country which led to deposition in swamps of nuggets that grew to impressive sizes. Might this be how gold was deposited within black sands? I can post it here if you`d like a copy.

I want to get an assay done of the black sands I'm recovering from an ancient glacial moraine here in New Jersey. They are heavily weathered, with the sulfides already oxidized. I notice a sizeable portion of them (about 20%) is a very fine, very dense 'silver sand', far heavier than iron, close to the density of the gold specks I see. I suspect it's a multi-metal oxide, probably of lead and silver and one other heavy metal.

 

[cosmetal]

I want to get an assay done of the black sands I'm recovering from an ancient glacial moraine here in New Jersey. They are heavily weathered, with the sulfides already oxidized. I notice a sizeable portion of them (about 20%) is a very fine, very dense 'silver sand', far heavier than iron, close to the density of the gold specks I see. I suspect it's a multi-metal oxide, probably of lead and silver and one other heavy metal.

Have you tested the "silver sand" for Pt?

Here in No. Calif., the bucket line dredges that were used to dig deep and go after old tertiary deposits within our rivers were digging up Pt deposits along with the Au. So much so, that the State geologist suggested that the miners accumulate the Pt also.

"If the miners could be persuaded to collect the platinum minerals, an industry might be established of considerable importance. There is no reason why platinum should not be manufactured in San Francisco and an industry might be established of American demand in part or wholly supplied by this State. The process of manufacture is simple, the plant required inexpensive, and there are skillful chemists in the State fully competent to manage it. The control of the platinum trade is in the hands of a single English manufacturing firm, which has been the case for many years."
CA State Mineralogist_4th Annual Report - Minerals of California_1884

Unfortunately, since Pt won't amalgamate with the mercury used within the dredge's accumulators (as Au does), the operators simply viewed Pt as waste and it was discarded by the dredge's side chutes back into the rivers.

PM me if you are interested in reading this historic 1884 report. It is ~35MB so it's too big to post here.

Peace and health,
James

 

[cosmetal]

I want to get an assay done of the black sands I'm recovering from an ancient glacial moraine here in New Jersey. They are heavily weathered, with the sulfides already oxidized. I notice a sizeable portion of them (about 20%) is a very fine, very dense 'silver sand', far heavier than iron, close to the density of the gold specks I see. I suspect it's a multi-metal oxide, probably of lead and silver and one other heavy metal.

https://www.amazon.com/Royal-Gold-C...oods&sprefix=miller+table,sporting,355&sr=1-1
I would suggest that you get (or build) a small Miller Table - ball mill your sands to <100 mesh - and slowly (that's the only way a Miller Table seems to work) run your sands over the Miller Table and send that sand sample in for assay.

Peace and health,
James

 

[Alondro]

https://www.amazon.com/Royal-Gold-C...oods&sprefix=miller+table,sporting,355&sr=1-1
I would suggest that you get (or build) a small Miller Table - ball mill your sands to <100 mesh - and slowly (that's the only way a Miller Table seems to work) run your sands over the Miller Table and send that sand sample in for assay.

Peace and health,
James

The sands are already so fine, I think a simple smelt-and-cupel assay using lead as a collector will work just as they are. They've been crushed and ground by ice, water, and rocks grinding for 10,000 years. Much of it is fine dust, especially the interesting silver sands fraction.

Since it all comes from panning, I won't have more than 10 pounds of it every year. This is just to see if there enough PMs to make it worth saving the sands up year after year until I have a good pile.

If a pound of it sent for the assay produces a noticeable bead of metal after cupeling, then it's certainly rich enough to save.

Sent an email to Mount Baker to see what their price for a fire assay is. I've watched dozens of the smelts on Youtube, and Jason is exceedingly skilled at the process.

 

[Deano]

Gold assays on black sands are always subject to nugget effects.
This is minimised by running the assay in triplicate, it often stops you getting excited over one large piece of gold in a single assay.
Deano

 

[Alondro]

Gold assays on black sands are always subject to nugget effects.
This is minimised by running the assay in triplicate, it often stops you getting excited over one large piece of gold in a single assay.
Deano

There won't be any 'nuggets' in my sands. They've been panned down to only the finest particles and mixed thoroughly. Also, they're the combined sands of half a dozen spots in the area I'm working. It's a very good general homogenized sample,

 

[Wolfpacker1]

Does any body know of a good leaching process for a 5 ton a day operation? Cyanide is very difficult to permit. The sands are predominantly magnetite, but still contain about an ounce per ton in unrecoverable ( by tabling) Au. I haven't done an ICP to see what all contains. This would be processing from multiple areas, on a 5 ton per day basis. Any thoughts would be appreciated, TIA.

We use a thiourea based leach to recover gold from magnetite, black sands and sulfides where cyanide has failed. You can visit our website at tcbinter.com
We have a page devoted to black sand processing

Edited due to forum rules and strange double quoting

 

[Wolfpacker1]

Does any body know of a good leaching process for a 5 ton a day operation? Cyanide is very difficult to permit. The sands are predominantly magnetite, but still contain about an ounce per ton in unrecoverable ( by tabling) Au. I haven't done an ICP to see what all contains. This would be processing from multiple areas, on a 5 ton per day basis. Any thoughts would be appreciated, TIA.

Depending where this material is located and how far from a port , I have clients that would be interested in this material.

 

[Golddigger76]

If you zoom in on the picture you'll see how it flakes where the edges have been hit, it has the appearance of chert or flint

 

[Yggdrasil]

If you zoom in on the picture you'll see how it flakes where the edges have been hit, it has the appearance of chert or flint

Which picture are you commenting?

 

[goldshark]

To give a final update on our decision to process the black sands; the final assay report came back at 4 grams per ton, on the 2 ton super sack I sampled from. I also did an ICP, any body need Cesium? It runs almost 1%. Fe was in the 58% range, nothing else standing out for values. Most of the material has been classified to -20 mesh, and ran across a good table, good operator. Located in Colorado, at least 500 tons available. I also did a separation of the whole, into varying mesh cuts. Out of the general lot, I took a cut at 50 mesh, 100 mesh, and 150 mesh. Fire assay showed almost the same Au in all samples. This leads me to believe finer grinding would not expose or liberate, a higher quantity of recoverable Au. Cyanide is a real mother to permit. Have an acquaintance who put 25 million into a Cyanide plant, built to state regs. Just as they were about to start processing, the state comes in and says they want a secondary liner behind all Cyanide potential leak components. Basically a secondary under leach pads, tanks, pipes, Carbon columns, and any other thing associated with the process. Just wanted to inform anyone who may process in the future, build a pad under your pad, or the state will shut you down. Seeing this across western US.
Long story short, this has not been reprocessed. Might wait for the Cyanide plant to get up and running. See if they can do any thing with it. Any other markets for ground magnetite that you guys know of? I have heard petroleum refiners consume it, but I haven't looked into that yet.

 

[Alondro]

To give a final update on our decision to process the black sands; the final assay report came back at 4 grams per ton, on the 2 ton super sack I sampled from. I also did an ICP, any body need Cesium? It runs almost 1%. Fe was in the 58% range, nothing else standing out for values. Most of the material has been classified to -20 mesh, and ran across a good table, good operator. Located in Colorado, at least 500 tons available. I also did a separation of the whole, into varying mesh cuts. Out of the general lot, I took a cut at 50 mesh, 100 mesh, and 150 mesh. Fire assay showed almost the same Au in all samples. This leads me to believe finer grinding would not expose or liberate, a higher quantity of recoverable Au. Cyanide is a real mother to permit. Have an acquaintance who put 25 million into a Cyanide plant, built to state regs. Just as they were about to start processing, the state comes in and says they want a secondary liner behind all Cyanide potential leak components. Basically a secondary under leach pads, tanks, pipes, Carbon columns, and any other thing associated with the process. Just wanted to inform anyone who may process in the future, build a pad under your pad, or the state will shut you down. Seeing this across western US.
Long story short, this has not been reprocessed. Might wait for the Cyanide plant to get up and running. See if they can do any thing with it. Any other markets for ground magnetite that you guys know of? I have heard petroleum refiners consume it, but I haven't looked into that yet.

It's odd to find cesium in black sands, which means they must originate from weathered deep magma deposits containing a large fraction of pegmatite ore bodies, such as pollucite, avogadrite, and pezzottaite. These only form during slow magma crystallization and occur only in a few known places in the world. The Tanco Mine in Manitoba, Canada has 2/3 of the known world supply.

It'd be interesting to know if the cesium mineral is bound with the hematite or is in 'sand' grains by itself.

 

[goldshark]

Whoops, the ICP stated Ce. Thought that was Cesium. I now mean Cerium, sorry, big difference.The source is near the very North end of the Rio Grande rift. Very interesting geology. youngest formation is Maroon formation, but because of the Graben ( Rio Grand Rift ), you can find the newer sediments abutting migmatites, and the tops of massive deep seated porphyry intrusions, which host the largest Molybedenum deposit in the world. Along with replacement deposits, various types of fault fissure veins, and placer deposits.
I am not going to do any more lab tests for this property. Last time I checked, Cerium was a buck a pound. So a couple hundred bucks a ton for a thousand tons, is not worth it to me. 1% Cerium = 22 pounds per metric ton, at $1 per pound = $22 per ton of black sand concentrates, + 4 grams Au at $60g = $240, for a total of $262 per MT. It would be about break even, and probably a loss, to get permitted, erect a mill, refine, then market the stuff for a 1/4 million dollars, solely for 1000 tons. Now if you had a mountain of the stuff, that would be a very different story.
Good catch Alondro.