A passive stripping system

[Rag and Bone]

How do you recover the silver?

 

[Shecker]

When you add the H2O2 the solution will turn yellow in color. That is silver coming out of the solution. Steve Spevak suggested it was silver and he was right. At this point I filter the solution, run a stiff wire brush over the surface of the boards to remove any stuck on copper/pm sludge, and back in the solution it goes. If the pm's are exposed the copper sulfate will strip them. But this is a metallic replacement process not a leach process. Copper will always be deposited where the pm's were -- that is why I go over everything with a wire brush after it has been in the solution for a few days.

After the resulting sludge is dried I smelt it to Dore. I was surprised to discover how much palladium was being recovered. During the smelt it formed a matte phase of a bluish-grey color on top of the copper Dore.
My first run was 40 ounces of copper, silver, and gold, and 7 ounces of this palladium matte material. The Dore came out silvery in color with an occasional showing of copper and gold. Check your solution when finished with it. It maybe that some of the gold is being retained in the leach and will require separate precipitation.

I started this as an experiment because copper sulfate is how nature transport precious metals in the environment. Now this is the only way I run e-scrap. I have an ore from which I am recovering gold and the yellow alkaline chloride of rhodium. The e-scrap runs itself while I work on my main project.

Randy in Gunnison

 

[Wyndham]

Randy, what do you think would happen with Black Sand cons.
Wyndham

 

[Shecker]

I don't know. I have never tried Copper Sulfate with black sands. But I did something similar once with interesting results. I had a black sand that was derived from a iron/gold mineral where the two were intergrown. From the host rock the mineral was gray and highly magnetic. Once oxidized it turned black and was still highly magnetic. I fused a sample of it with copper carbonate and found that the pm fraction seperated with the copper and became non-magnetic. This is one of the processes I use for intergrown iron and pm's. The fusion exchanged an iron base for a copper base and pm's were a hole lot easier to process. This material also had pgm's in it, which we (the New Mexico State metallurgist and I) proved at the New Mexico Bureau of Mines by froth flotation using a xanthan collector and Dowfroth 250. So a black sand that would not assay values in platinum group metals would float them. Try it and let me know the results. I would suggest using a little H2SO4 with the CuSO4 to keep the pH about 2. If this works it shouldn't be any problem to precipitate any values using standard means. The iron weill drop copper out of solution and also pm"s.

Randy in Gunnison

 

[Wyndham]

Thanks this looks very promising on several fronts. I have an aquaintance that has a placer deposit in a pay to play site but the super fines are in a mud cake that has an unknown value and the profit is selling buckets to play in, so this might be a good test. Thanks Wyndham

 

[Shecker]

Clay is one tough sadistic S-B, if you know what I mean. But it can be broken with the right approach. I once heard that some guys near Durango, Colorado, were recovering gold from a red clay by putting the clay in 55 gallon drums and boiling it over a camp fire. The heat breaks down the clay. By cooking and stirring they would have a layer of clean gold in the bottom of the drum after about 12 hours of applying heat. Another method is to take prickly pear cactus, burn off the part that sticks, cut into long strips, and soak in water for 3 months. This will produce a gelatinous material that breaks up clay and has no environmental impact (since it is a natural product). Once the clay has been broken the gold can be recovered by standard means. I don't know if copper sulfate will have an effect on clayey materials but it wouldn't hurt to try.

Randy in Gunnisonm

 

[Rag and Bone]

Could you post some photos? I would love to see one of the dore bars. I'm also curious to see how the boards hold up after the process. Do all the components dislodge?

How much material did you process to yield the 40 oz. bar?

 

[Wyndham]

The nature of clay is that it is thin platelets of silica and alumina with impurities like iron for red clay or weathered feldspar that has given up its fluxing agent sodium or potassium or lithium and may come from underwater volcanic smokers that may be pregnant with copper or other metals or barren like Kaolin, just alumina & SIO2(I think) so the heating make sense since at about 900 deg it is calcined and looses it's sticky. Tobacco juice will also break down clay but I don't chew, :mrgreen:
I like the boiling idea, maybe with a touch of either alkali or acid. there is I believe an ionic bond going on that has to be broken for the clay to loose it's sticky. This might be an interesting path to follow for awhile. Wyndham

 

[Shecker]

Rag and Bone I have been trying to get some pictures up but haven't been able to get them beyond tinypics. I could e-mail them to someone who could then post them.

Wyndham the ore I am working on comes from an underwater volcanic smoker and it is a real complex bugger. Since our black smoker injected some of the minerals as a chloritic material. My ore also possess a rather large amount of clay but it doesn't interfer with the extraction I am doing.
I use a hcl-cl leach employing 3 and 1/2 liters water per pound of ore, 100 mls chlorox, and 400 mls hydrochloric acid. The leach takes about one hour.
I use cloth sheets as a filter and colanders that fit nicely over a five gallon bucket to filter through. Ferrous sulphate recovers the gold and then a small amount of ammonium hydroxide recovers the platinum as yellowish-orange ptcl(2). Then a little more ammonium hydroxide produces a deep blue solution I poetic call the "blue solution of death" as everything at point becomes virtually impassive. But add a little hcl and yellow alkaline rhodium chloride develops. I currently have 120 ounces of alkaline rhodium chloride available and I am waiting to hear from a refinery to see if they want it. I also have about 150 ounces of gold.
This blue solution is caused by the reaction oif the hypochlorite ion and the rhodium ion. I also have pics of this available.

Randy in Gunnison

 

[Anonymous]

Could someone explain the chemistry behind this to me, I do not understand how copper sulfate can strip more noble metals.
Thanks,

Jim

 

[Shecker]

I call this a transport system, not a leach system. But calling it a metallic replacement system would also be accurate. Copper sulfate (and to a lesser extent ferric sulfate) is nature's method of transporting precious metal ions in the process of oxidation. In the case of the passive stripping system I am exchanging copper ions for ions of silver, gold, and pgm's. I don't know about you but trading copper for silver, gold, and palladium is highly profitable, at least I think so. And it is cheaper than other approaches, has less environmental impact, and doesn't mess with the solder. But it is all a matter of personal preference. You will go on using what you use and I will go on using what I use. It is a matter of what we are comfortable with and use to (and yes I do suffer from dangling participles).

Randy in Gunnison

 

[Rag and Bone]

What kind of fumes does the reaction emit?

(very interested in this method, thanks for posting Shecker)

 

[Shecker]

There are essentially no fumes, at least during the initial bath.

Randy

 

[Platdigger]

Still, it does seem backwards doesn't it.

I mean, a base metal will always displace a precious one just by virtue of the electromotive series of forces.........right?

And by this, I of course am refering to one metal being more chemically active than another. Or is it "electrically" active?
Which ever it is....

There must be some other way to explain this sytem of recovery.......

Now with ammonium thiosulfate gold leaching.....copper sulfate is used as a catalyst........but this is different.
Randy

 

[Lou]

Does seem backwards, doesn't it? :lol:

 

[eagle2]

Well guys. The best thing is to try it for ourselves. Gold may form some type of temporary complex with the Sulfate ion, with the help of the H2O2. Silver forms Ag2SO4, which is mostly insoluble, 1 or 2% stays in solution. Looks like Pd is also separated.

I am definitely going to try it.

Randy, did you use any Sulfuric acid to lower the Ph? Cupric Sulfate is Ph 4 in water by itself. Do you use tap or ground water or distilled water? Gold shouldn`t stay in solution at all unless there are some Cl- ions in the tap water.

Al

 

[Anonymous]

You will go on using what you use and I will go on using what I use. It is a matter of what we are comfortable with and use to (and yes I do suffer from dangling participles).

Randy in Gunnison

Randy, I was/am not trying to impune your system. I just personally do not know/understand how it works and would like too.

Thanks,
Jim

 

[Wyndham]

I remember taking a mine tour many years ago near Idaho springs above Boulder, this was before I got interested in the chemistry of gold. The mine had an ore that looked like a black clay/sand mixture in the walls and posts that we went through. This makes me wonder about the Co, area and what other black smokers might still be undisturbed hmm.
Gold fever is a wonderfully terrible thing. Thanks for the info, Wyndham

 

[Shecker]

I have no problem with someone impuning what I say. That is how knowledge is developed. I use tap water and no acid. Perhaps there is a reaction between the Cl from the tap water and the SO4 from the Copper Sulfate. That is something I hadn't thought of and that could part of the driving force of this reaction. That may also explain why the silver comes out as a yellow complex, because a chloro-sulfate of silver would be yellow in color. This is definitely something to think about.

When I treat e-scrap with this solution I notice that the gold fingers slowly dissolve leaving the underlying copper intact. I believe that this is a dissolution process because I see no visible gold in the copper sludge that develops until it is smelted. But then again I do not see any visible palladium either until it is smelted. Only the silver shows up as the bright yellow complex. It does not react on anything that isn't exposed so I beat the living stuffing out of the boards before treating them. A great stress reliever. How long to I treat the e-scrap? When all visible gold is gone from the boards I scrub them down with a wire brush. There is always copper sludge adhering to things. Then I wash them to remove all of the scrubbed off sludge and they go to the trash heap.

I get the e-scrap for nothing by putting an add in the local paper. The extraction costs are minimal. $10.00 for a pound of copper sulfate (which goes a long ways) and $1.00 for 3% hydrogen peroxide (I use 3 to 4 of these per batch both to react out the silver and to get the ORP of the solution up). So about $14.00 to $15.00 dollars I recovered 40 ounces of metal including 7 ounces of palladium. I am waiting for the refiner I sent this to to tell me how much gold and silver is in it.

I have more of this Dore. If someone on the forum wishes to handle it please pm me. I also have some lead based Dore that contains pgm's.
If someone wishes to handle that please pm me.

Randy in Gunnison

 

[Rag and Bone]

Has anyone tried this method using an aerator? I wonder if it would revive the solution similar to AP. It would add some agitation if nothing else.

I started a trial batch of copper sulfate, h20 and H2O2 with a variety of e-scrap items. The addition of H2O2 turned the solution slightly yellow for a while. A precipitate is developing that looks like gold powder although nothing is visibly stripped yet.

I hope this method works. It sounds too good to be true so I'll try not to get too excited.

edit (next day)

Today the scrap in solution was fizzing like it was in a cell. A light brown precipitate is developing and gold has begun to strip. The monolithic caps. on some old modems formed a white "fuzzy" coating. I didn't alter the scrap, just threw in some assorted pins and fingers, 386 cpu, monolithics and eprom.