Gold in Arsenopyrite

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usaman65

Well-known member
Joined
Dec 7, 2007
Messages
121
Location
nj
Hi-

I have some gold ore (that I can get a LOT more of) that is roomered to contain 16+oz of gold per ton. Im getting an assay, but until then I would like to know a good way recoverying the gold out of the ore if it proves to be worth while based on the assay. It is arsenopyrite, It contains arsenic, Iron, Gold, and cobalt to my understanding. The place was accualy a cobalt mine in the 1700's for the textile industry, the gold was only known since the 1960's. Since it is a sulfide ore, should I bake it to expose the gold and to break up the pyrite and arsenic? or should I grind it and hit the chems?

I know there was a post about recovering gold out of pyrite o this forum, but I think arsenopyrite is a totaly different story.

kev
 
Heat will destroy the both the sulfides and the arsenides. If it is arsenopyrite then you are dealing with a refractory ore. 16 oz/ton sounds enticing, but it will not be easy to get it out, especially considering a ton of pure material is over 30% arsenic by mass. You could make some money off the arsenic as well as the gold!

So you have FeAsS with gold entrained in the lattice. You have a tough extraction. Heat will burn away the sulfur, but it will also oxidise away the arsenic to volatile arsenic compounds. Hot, medium conc. nitric acid will accomplish the same effect and remove both the sulfide and any arsenic present by oxidation. I don't recommend it though, firstly because it loves accumulating in your system, and it's damn toxic. If that's not enough it's also a Group I Human carcinogen according to the IARC. I'd rather work with cyanide every day, because that just outright kills you if you mess up and it isn't slow and painful (plus, I like my hair, As poisoning and you go bald! insult to injury!)

In my opinion, your best bet is to leave it to the professionals. And if you are a professional and have all the equipment to adequately roast it, by all means, go for it! Hell, call me up! I can do with some more consulting work :) I won't tell you any details unless I'm on the clock.

:wink:
 
Arsenopyrite can kill you in short order if not processed properly. It sent me to the hospital last fall and I still have problems from it. It was just a small sample of only a few ounces. I doubt if there is much of a market for Arsenic anymore since pressure treated wood with Arsenic is more or less a thing of the past. The disposal fees will cost a lot to properly dispose of it. There are small mountains of it in the Nevada desert that nobody wants.

Dangerous stuff.
 
This could be a stupid question, but a friend fo mine collects minerals etc and said he found some arsenopyrite (and other pyrites)... is the stuff dangerous at all as is? (i.e. not beign processed, but just as a specimin).
Just kinda curious
 
There is a natural occurring arsenide of gold. It looks like arsenopyrite.
Try a little sodium hydroxide on it. The samples of gold arsenide that I have tested have reacted with NaOH causing the gold to come out of the crystals.
But watch it -- the fumes can be a little weird so do this outside and get down wind from it.

Randy in Gunnison
 
Shecker said:
But watch it -- the fumes can be a little weird so do this outside and get down wind from it.

Randy in Gunnison
Click to expand...

I think you mean upwind of it, or have it downwind of you.
 
Usaman,
From what I've read, It' pretty hard to break.
The books say it weathers to scorodite.

Also,... looks like your in a good area.

Just be careful of any Uraninite that might be in the mix if it was formed in
high temp.
Irons,
They still make syphillus drugs with arsenic ...right?

Mark
 
If you have, or can get a furnace, instead of leaching it, you could smelt it to lead by mixing your ore with lead and smelting it until all is molten together, then pour this mix to a lightly greased mold. the slag may fracture violently as it cools , so wear eye protection, and other appropriate safety gear, and don't stand over the top of it watching it cool. When cool, turn the mold over and the slag and lead should fall right out. Tap the point at which the slag and lead come together with a hammer, and the slag should pop free, not always though, sometimes you have to beat on it. This lead is the collector for the pm's, and can be reused for the next batch as well. At some point the lead will start to become hard. At this point the lead can be placed in a scorification dish in a furnace to reduce the bulk of the lead to litharge, thus removing the arsenic and a alot of other impurities as well. The lead at this point can either be granulated, and dissolved in aqua regia, then follow the procedures listed on this forum for recovering pm's from this solution, or you can use industrial cupellation. This process draws off the lead into the cupel leaving the pm's as a dore bead that can then be further refined with the methods found on this forum. This process works with black sands, and would work with electronic scrap as well. Sincerely; Rick. :!: :idea: :D
 
Richard36 said:
I am surprised that no further posts have been made on this thread. where's the interest people?
Click to expand...

Well lets see.

Lou's not going to tell us anymore details unless he's on the clock. :wink: :)

Irons has had just about enough of Arsenopyrite. Get well soon.

Shecker wants to: Try a little sodium hydroxide on it.

James wants to stand upwind of Shecker's experiment, regardless of where Shecker stands. :wink:

geubrina wants to know whats happening.

And usaman65 never responded to any of the responses that he received.

Me? I'm just reading. Sounds like some dirty, toxic, problematic stuff to me. I'm afraid Lou might be too optimistic about the market for arsenic. As Irons said, their not using it anymore to treat wood. In the process that you described, where does the arsenic end up?

Regards to all.
John
 
semi-lucid said:
Richard36 said:
I am surprised that no further posts have been made on this thread. where's the interest people?
Click to expand...

Well lets see.

Lou's not going to tell us anymore details unless he's on the clock. :wink: :)

Irons has had just about enough of Arsenopyrite. Get well soon.

Shecker wants to: Try a little sodium hydroxide on it.

James wants to stand upwind of Shecker's experiment, regardless of where Shecker stands. :wink:

geubrina wants to know whats happening.

And usaman65 never responded to any of the responses that he received.

Me? I'm just reading. Sounds like some dirty, toxic, problematic stuff to me. I'm afraid Lou might be too optimistic about the market for arsenic. As Irons said, their not using it anymore to treat wood. In the process that you described, where does the arsenic end up?

Regards to all.
John
Click to expand...

The Arsenic is an expensive disposal problem and the environmental police don't look kindly on anyone who cuts corners.

Any toxic residues have to be disposed of properly and properly means an approved method and disposal facility. It's expensive.
 
Complex ores need better treatment than cyanide process..i.e. thiosulphate process,Halogen process...they are alternatives.The gold contents seems to high for me.

In 2008 8 new mines opened in Mexico...the best one has 3.5 gr of gold/Tn of ore....the others have 0.8-1 gr Au/Tn ore.

Why do not you take a look to the potassium iodide process for gold recovery?..It is here in the Forum.

Regards

Manuel
 
heating up Arsenopyrite?.. :shock: the thought of anyone without a mining background/experience and not under strict EPA regulations processing something this dangerous.. that scares the hell out of me.

"When arsenopyrite is heated, it becomes magnetic and gives off toxic fumes. With 46% arsenic content, arsenopyrite, along with orpiment, is a principal ore of arsenic. When deposits of arsenopyrite become exposed to the atmosphere, usually due to mining, the mineral will slowly oxidize, converting the arsenic into oxides that are more soluble in water, leading to acid mine drainage."

http://en.wikipedia.org/wiki/Arsenopyrite

http://www.cepis.ops-oms.org/bvsacd/arsenico/Arsenic2004/theme2/paper2.2.pdf

http://www.sciencelab.com/xMSDS-Arsenic-9922970
 
I don't think the levels are exceptionally high, it all depends on the size of the mineralization and how much surrounding rock must be removed to get the ore.

There is an old mine 150 km from where I live. The mineralization was found a hundred years ago and consists of quarts veins with massive arsenopyrite. The guy that found it thought that it might contain cobalt so he sent some samples to a smelter. When he got the results back he hardly believed it. Over 1500 g Au per ton for the best arsenopyrite specimen. The gold was so finely dispersed in the ore that you could only see it with a microscope.
But the veins were vertical, too thin and too far between to ever be mined economically. Still today the only trace from that period is a number of ditches crisscrossing the woods in an area a couple of hundred meters across.

The modern mines in the area is driven in ores with a couple of grams per ton but with millions of tons of ore. To successfully drive a modern mine you need the economics of size to offset all fixed costs. Small mines could have fantastic high gold contents but if the ore is too small it isn't worth the start up costs.

The most common ore processing here is crushing coupled with flotation to create a sulphide concentrate sent to a smelter. At least one mine is using gravimetric concentration to get a gold concentrate before using flotation of the rest to get the sulphides that also contains gold and silver. One or two mines use cyanide leaching in a couple of big agitation tanks.

edit: spelling
 
g_axelsson said:
The most common ore processing here is crushing coupled with flotation to create a sulphide concentrate sent to a smelter. At least one mine is using gravimetric concentration to get a gold concentrate before using flotation of the rest to get the sulphides that also contains gold and silver. One or two mines use cyanide leaching in a couple of big agitation tanks.
Click to expand...
g_

I was hoping you might comment on this, since you have mentioned arsenic bearing ore in another thread.

How is the arsenic disposed of at the mines that you mentioned :?:
Do they bury it?
If they grind the ore to a powder, do the cemment it together somehow?

Thanks.
 
First of all, the smelter I'm talking about is Rönnskärsverken, one of the largest smelter and refinery in Europe. It's owned by Boliden mining company.

The arsenic is following the other sulphides in the concentrate sent to the smelter. There the ore is roasted.to drive off sulphur and arsenic. The arsenic is collected in large filters, collected and deposited in large storage areas lined with rubber and watertight clay to stop leakage into nature. The plan is to use an old abandoned mine to store the waste in. The mines here goes down to 1200 meters depth so far.

This is all done on industrial scale, the local smelter treats the concentrate from a number of mines around here. Total amount of sulphide concentrate processed in 2007 was 600 000 tons plus 110 000 tons of scrap metal and 36000 tons of electronic scrap. The interesting part of the production was 12 ton gold, 347 ton silver and 214 000 ton copper.

The arsenic is a contamination in the ore, there is more than enough to cover the world consumption many times around so the mines are paying fines depending on how much arsenic there is in the ore.

Whenever I collected metallic arsenic as mineral specimens they just smiled. I don't think it mattered in any way but I collected 50-100 kilos of almost pure arsenic. Almost pure, as the arsenic actually contained circa 10% silver. :D
 
Interesting. So what was the volume/weight of the arsenic contaminated waste per ton of ore? (typically)

John
 
semi-lucid said:
Interesting. So what was the volume/weight of the arsenic contaminated waste per ton of ore? (typically)

John
Click to expand...

I've run into 'ore' that was over 50% As by weight.

It had a small amount of values, but not enough to cover the cost of disposal, let alone chemicals.
 
I have no idea of specifics on what the smelter processed. I've only visited these places, never worked there.
For the mine that I know best I would make a guess that it was a couple of percent compared to the copper contents. The ore that I've seen ranged from pure chalcopyrite boulders of several tons to almost pure arsenopyrite in 10 kilos pieces.
 

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