A passive stripping system

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P_Carrol. Earlier in this thread I reported an exeriment with a Silver plated butter dish. The solution was tap water, CuSO4, H2O2, and a small amount of H2SO4. After a few days The plating was very loose or had disintigrated. some scraping work was necessary to get it all off. The solution attacks the copper base and the Silver does not go into solution.

With steel base nuts you may have a different result.

THIS process everybody is disscussing is nothing but a Copper leach, similiar to the AP process (with HCl).

The difference is that Copper does not form a Cuprous Sulfate (in the AP process it forms Cuprous Chloride which is not very soluble and quickly slows the leaching reaction).

Copper Sulfate (Cu II, should be called Cupric Sulfate) is reduced in the reaction to Cu I. Then it forms a Sulfite or an Oxide. This is Cuprous Sulfite (Cu2SO3), which has several varying compound forms, red to pale yellow to white in color, or Cuprous Oxide (Cu2O) (color may be yellow, red or brown). Cuprous Oxide breaks down in dilute H2SO4 to Cupric Oxide (CuO) and elemental Copper.

Also in the sludge at the bottom is Elemental Sulfur, salts and the PM`s broken down to fines or whole bits of foils. The presence of Sulfur indicates that the Sulfate ion also enters the reactions going on(Probably reacting with the H2O2 or O2 in solution).

I am still experimenting with small batches and will report more later.

I like it so far, because the solution stays cleaner and needs less attention than AP with HCl. Also Iam not using any heat. Also the constant formation of bubbles forms a mechanical action that seems to easily break the foils and leach the base metals to a greater extent, than AP with HCl.

You can Google Copper Sulfate leach and get a ton of info to study.

Al
 
My theory is inline with eagles that the coper alloyed with the silver is attacked and goes into solution. So far after adding h2o2 and a ratio of about 3/4 ponds of copper sulfate and 3 gal of water the solutoion has turned a dark bluish grey and is bubbling indication some type of reaction going on.
 
Shecker said:
Certainly there was a great deal of copper building up from reaction with steel and aluminum components and I believed that any pm's would accumulate with the copper. I did not anticipate that monolithic caps would also be stripped.
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That should have sent up a red flag for you. It's obvious, at least to me, that you were reducing copper sulfate with base metals, so copper would be the largest component of your doré. In a sense, you melted the metallic portions of the board without fire. I would expect very little in the way of values. I would still be at a loss to understand where the silver came from.

They wanted it but did not bother to tell me until after they received it that they have a significant remelt fee.
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Another red flag, one you should have observed closely.

I have submitted values to refiners on several occasions----and have never been asked for money up front. I've been cheated, but they have done that by under reporting the results.

That they wanted money up front is a clear indication, at least to me, that what you submitted was very low in value, too low to process at a profit (for them, perhaps not for you). Any money you throw at this venture will be a loss to you.

You made your mistake by assuming percentages. It's clear you had no idea what you had----and should not have been promoting this system until you knew more. I've taken note that you have advised others to emulate the process. Please refrain from doing so until you have evidence that the process is valid.

An honest answer to the question of the volume of boards processed would be very helpful in concluding what has happened here. Our friend GSP appears to have a firm grasp on what should be expected, as does Lazersteve (based on the volume of boards processed).

I remain a skeptic. I'm even more so, having done a search on your previous posts (I recommend readers follow suit, to get an idea of the nature of the claims being made), all of which make grandiose claims----none of which have been substantiated in practice.

I'm particularly troubled by your reports of platinum group metals reporting in the hundreds of ounces per ton. Can it possibly be that you are the only person alive that finds these metals, when highly skilled and educated people fail routinely?

It's time for a reality check, Randy. A good way for you to restore some semblance of credibility would be to provide some scans of assays that have been performed on your materials. No assays? No credibility. Just claims by a delusional dreamer.

I have my fork in hand, ready to eat crow.

Harold
 
Attached is a close up pic of the nuts after soaking in the keach solution overnight. there were grey particles in the bottom of the bucket as well.Nuts were returned to solutin for further soaking.
 

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P_Carroll. That`s a lot of nuts :) With that large of a batch you will use a lot of H2O2. One of my planned experiments with a large batch was to switch to a fish tank bubbler, to see if the results would be the same.

The gray you report on the bottom will contain the Silver that has flaked off. Also its important that that the solution is slighly acid, otherwise the reaction will stop. Add small amounts of Sulfuric acid. The literature says leaches are run commercially in dilute solutions, PH under 3. I`ve used more concentrated solutions with a PH under 1. More acid will speed up the process, but will also decompose the H2O2 a lot faster.

What Randy thinks is Silver on the boards, may only be Tin, but it is aslo possible he has boards that used Silver containing solders?

Also some old mainframe boards used Gold containing solders.

Al
 
Eagle2, I wonder if really you are taking sulfate to sulfite to elemental sulfur. You need to substantiate that to me--sulfate is a very chemically stable anion (resonance stabilized) and doesn't get reduced without one heck of a fight. There's nothing in this system capable of doing that.

I don't buy it at all.
 
I added more H2O2 and the bubbling began again vigorously. Im thinking that the silver goes into solution momentarily but the copper of the copper sulfate pushes it back out of solution. Also setting up a drip for the H2O2 might be beneficial to replenish the solution. But what do I know I could be wrong and this could be a colossal waste of time. I will be testing the powder at the bottom of the bucket to see if it contains silver later on.
I will be posting another pic of the progress tomorrow.
 
Lou, I don`t claim to know all the chemistry going on. but there are several strong drivers in the solution. There are probably dozens of reactions going on. I mentioned Sulfite, because there is no such compound as Cuprous Sulfate. It does not exist normally. However I did some reviewing and you are right. A Sulfite is not going to be produced here. But Cuprous Oxide does (Cu2O). This breaks down to Cupric Oxide (CuO) and elemental Copper in the leach.

The main drivers have to be Copper going from +2 to +1. Sulfuric acid and Peroxide. My mention of elemental Sulfur is pertinent only to when this leach is used with a complex Copper ore.

Thanks for making me be a little more accurate.

Al
 
As promised here are some more pics. First one is what looks like silver floating on the surface.
 

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Yes! That looks like action. Careful with the liquid. You don`t know what alloy composed the base part of the nuts. Also there could have been some Cadmium with the Silver plate.

Al
 
I would like to share that just yesterday I found my copy of Bureau of Mines Report of Investigations 8561, entitled "Recovery of Copper and Associated Precious Metals from Electronic Scrap." This report advocates the use of acidocupric sulfate (copper sulfate and H2SO4) for the processing of e-scrap. In the system they advocated that copper sponge containing the pm's is smelted, put into an electrolytic cell where pure copper is plated on the cathode and the pm's are recovered as an anode slime.

Randy in Gunnison
 
Very big difference between using copper sulfate and sulfuric acid in conjunction with electricity as compared to just soaking parts in copper sulfate and sulfuric acid.

I tried parting by the electrical method. I'm not here to dispute that it works, but if the precious metal content is high, or if the level of contamination by base elements beyond copper are high, it fails miserably. Note that GSP has alluded to this very process numerous times, where e scrap is combined with copper for recovery of values in the copper refinery. It's important to success that there be low contamination levels. Otherwise copper is deposited as sponge, sloughing off and settling in the slimes instead of adhering to the cathode(s).

I would suggest to you that when e scrap is melted with copper, it is done in large reverb furnaces, where the base metals are oxidized and discharged in the slag---or discharged in the gases (think zinc) raising the level of purity of copper.

Harold
 
Once in the far past when I smelting ores on copper and then electrolytic separating the copper to obtain a pure copper cathode I noticed the same problem. I solved the problem (at least as far as my small scale works was concerned) by wrapping the cathode in a bag and periodically collecting the copper sponge for re-smelting with ores. That was I had some clean copper and a constant supply of copper for remelt. In addition when dried the copper sponge was in a powdered form and was far better for collecting pm's than wire or other forms of copper.

Randy in Gunnison
 
Just a quick update that I recovered a little over 11 grams of cement silver not including the stuff trapped in the filter that i couldnt get out. I can send out a few small samples for testing if anybody would like to verify my results.
 

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