First time processing RAM fingers

[Stewill]

Hello,

Long time lurker here, first time posting!

I've been recovering gold from ceramic CPUs for about a year now using AR, cooling it to get the silver chloride out, neutralized with Urea and finally drop out the gold with SMB. So far so good with ceramic CPUs, but I had a load of RAM boards knocking around and decided to do them...

After trimming all the boards I was left with about 600g of fingers:

I ran them through an AR solution until all the gold had gone, got silver chloride out, neutralized and put SMB in and left over night. I did this instead of using HCL and peroxide as I didn't have any. I've ended up with this:

I haven't had a drop like this before as it's too light and alot of it. This is the first time I've done RAM boards and was unsure what I've ended up with....

Thanks

 

[Anonymous]

If you left the fingers as they were in the first picture prior to processing then there was a lot of extra material that went through your AR (assuming that you went straight to AR however you haven't clarified that yet.)

There were various components on the boards, so you have other metals in there.

If it were me- and this is naturally very subjective, then I would treat that first dissolution in AR as recovery and process the powder in the jar again in AR to refine it. I'm sure that plenty of people will offer differing opinions though.

Jon

 

[Stewill]

Yeah I left then as they were in the picture.

Have now washed the material that was left and have gotten most of the brown out and looks much better, waiting for it to settle before drying it now. Will re-run the grey stuff again to make sure tho.

 

[bswartzwelder]

This is an ideal example of where a little reading would have saved you a lot. A lot of time, a lot of trouble, and a lot of waste.

You now have a mess. One that will be much more difficult to handle than need be. First, AP and NOT AR should be used in treating gold plated finger contacts. It would have gotten rid of the underlying metals and left little flakes of gold floating around in the liquid. Then, treating the foils which were left from the AP with AR, acid/Chlorox, or poormans AR would have yielded a much cleaner solution to deal with.

I suggest you put everything aside before you make more mistakes. Mistakes which could impact your health and the health of others around you. Mistakes which will cause you to lose your values. As it is right now, all your gold is tied up in that gray colored mud. It won't go anywhere.

Next, you need to read. Read Hoke's wonderfully enlightening book. Read the forum. Once you are finished with that, read it all over again. At that point, you should have enough education to begin your adventure into recovery and refining. You will learn that what works well for one type of material doesn't necessarily work well (or even at all) for another type of material. Do the acquaintance tests she mentions and observe the results. Those results will lead the way as to what you should expect.

Don't forget to mix up your test solutions while you're at it. They will serve you well when you need them.

 

[g_axelsson]

Aqua regia on circuit boards is a bad idea. Some of the gold that dissolves will cement back on the copper layers buried in the boards and become even harder to extract. I made that mistake once when I added two fiber processors to a batch of ceramic CPU:s in AR... read more about it here http://goldrefiningforum.com/phpBB3/viewtopic.php?f=60&t=17697

The grey sludge looks like metastannic acid, a result of putting boards with tin in AR.

Göran

 

[Stewill]

This wasn't that much trouble, more just a learning experience. Will do an AP next time to get the foils off, but after washing several times have managed to get some out of it.

Like I said before have only been doing Ceramic CPUs, so far I'm up to 22g of Gold, I've had it tested and has come out at 20 carat. Will keep to doing them for now...

 

[Anonymous]

Aqua regia on circuit boards is a bad idea. Some of the gold that dissolves will cement back on the copper layers buried in the boards and become even harder to extract. I made that mistake once when I added two fiber processors to a batch of ceramic CPU:s in AR... read more about it here http://goldrefiningforum.com/phpBB3/viewtopic.php?f=60&t=17697

The grey sludge looks like metastannic acid, a result of putting boards with tin in AR.

Göran

Not necessarily Goran. If you cut your fingers close to avoid having other components and make sure you always maintain a slight excess of Nitric it's fine. I've done loads this way and the yields haven't been lower than expected.

Yes if you allow the reaction to finish i.e. You use up all the Nitric then you can run the risk of the situation you mentioned but that can be avoided very simply. The ease of using Sulphamic acid to get rid of the excess Nitric once you've poured the solution off the fingers (and washed them into the pour off) makes this a viable one step process.

Jon

 

[g_axelsson]

Jon contacted me via PM to discuss the refining of fingers via direct AR, but I suggested that we took the discussion here in the open so more people could pitch in with their thoughts and experience. Is anyone else except Jon running fingers directly in AR and what is your experience?

For many types of scrap there are more than one way to refine it and what is suitable for one refiner could be a bad process for another.

As for my experience, I have never done it so my statement above was based on my experience from running the fiber CPU:s together with ceramics. I would still avoid running fingers directly in aqua regia as there is a need to control the reaction a lot closer than the fire and forget process of either using copper chloride etch or straight nitric acid first and then refine the gold foils in a second step.

If you use copper chloride etch you have the added benefit that it also removes tin without forming metastannic acid and it can be filtered off before the gold is dissolved.

When refining fingers as a two step process the resulting gold chloride solution is quite concentrated, easily denoxed and minimizes drag down for a purer product or easier washing.

Anyone else care to pitch in with experience or just opinions?

Göran

 

[g_axelsson]

This wasn't that much trouble, more just a learning experience. Will do an AP next time to get the foils off, but after washing several times have managed to get some out of it.

Like I said before have only been doing Ceramic CPUs, so far I'm up to 22g of Gold, I've had it tested and has come out at 20 carat. Will keep to doing them for now...

Nice little compact loaf of gold.

I'm surprised that you don't reach more than 20 carat purity, was that tested with a touch stone and acids?

If you continue studying the forum you could easily get the purity up to 99.9% or better and create a mirror smooth surface. If you are in just for the money then the resulting purity doesn't matter much, but if you want to master refining then you should study some more.

Göran

 

[Barren Realms 007]

Jon contacted me via PM to discuss the refining of fingers via direct AR, but I suggested that we took the discussion here in the open so more people could pitch in with their thoughts and experience. Is anyone else except Jon running fingers directly in AR and what is your experience?

For many types of scrap there are more than one way to refine it and what is suitable for one refiner could be a bad process for another.

As for my experience, I have never done it so my statement above was based on my experience from running the fiber CPU:s together with ceramics. I would still avoid running fingers directly in aqua regia as there is a need to control the reaction a lot closer than the fire and forget process of either using copper chloride etch or straight nitric acid first and then refine the gold foils in a second step.

If you use copper chloride etch you have the added benefit that it also removes tin without forming metastannic acid and it can be filtered off before the gold is dissolved.

When refining fingers as a two step process the resulting gold chloride solution is quite concentrated, easily denoxed and minimizes drag down for a purer product or easier washing.

Anyone else care to pitch in with experience or just opinions?

Göran

Yes I run finger directly in poor mans AR. Once you have done it a lot you get the hang of it and there is not much of a need to keep a close eye on it. Its like anything else we do here, once you run enough of a certain material and you develop a process you know and understand you know what will generally happen during the process and when you need to check on it. You also know relatively well what will happen with additions of your chems and how much to add.

Ceramics and fibers don't belong together in a process though IMHO.

 

[Geo]

I have run all kinds of electronics in AR. It's not an easy thing to master. It's not something that I would recommend to a beginner unless they are already confident in their ability to extract gold from a solution of mixed metals including tin. The tin will have to be overcome by using excess oxidizer. That means neutralizing excess nitric before you can drop the gold and it will come down very contaminated. As long as the person understands what will be different and what they will have to do to recover the gold from the dirty solution, I say whatever gets the gold.

 

[rickbb]

I have run closely trimmer fingers in poor mans AR. It works well and it is much faster than the CuCl2 method of course.

But honestly CuCl2 and HCL/CL yields a cleaner product with less hazardous fumes being produced. In my opinion. Product from AR will need to be run through twice to get a good clean result.

 

[solar_plasma]

@Jon, Jeff, Barren Realms
I do not doubt your experiences. On the other side I like to add an observation of mine: A batch of high yielding kovar transistors in an ammount of AR that is not sufficient to dissolve it all, will test negative at any time, - excess or not. Also the gold platings stay visible and more or less untouched. First when almost no basemetals are visible anymore, the spent AR is removed and fresh AR added, it will test positive within minutes.

The excess of oxidizer cannot be the only variable that makes your experiences possible. What else might interfere I don't know, - maybe low areal of basemetal' surface to cement on, the basemetals low electronegativity (copper vs. Fe/Ni/Co), lack of electrical contact between gold and basemetal?

Probably all of them, but electrical contact seems to protect the gold in my case. Freely floating gold flakes do not have any electrical contact to basemetals (as sacrificial anodes) and are not protected. Then it might be the excess of oxidizer that minimizes or even inhibit the cementation.

 

[Geo]

Björn, The reactivity series of metals tells us that The most reactive metal will dissolve before any other metal and proceed down the series until it reaches gold. Theoretically it's true. In practice, variables such as heat and concentrations of acid effects which metal will react at any given time. If the solution is of an adequate volume and the acid is concentrated enough (but not too concentrated) and heat is applied, AR can and will attack all metal it comes into contact with regardless of whether it is more or less reactive than any other metal in the mix. If there is not sufficient acid to dissolve all the metal, the less reactive metals will cement out of solution on any base metal present. In the case of Kovar, the iron will cement gold out of solution before you can decant the solution away from the remaining metal, especially if you wait for the solution to cool. This is a major problem for people who have some knowledge but lack in experience. They dissolve the metal that is highly visible (gold foils) and it cements back out as a brown to black powder that looks very much like dirt. This is the most common mistake a rookie can make when using AR and they misplace their gold. I test all solutions before I move on to another step. As redundant as it sounds, I test when transferring solution from one container to another. I test before I transfer and again after. If you move things or add something or remove something a couple of times without testing each step, by the time you realize that something isn't right, you have no idea where it went wrong. Now you have to back track to see where your target metal has gone.

 

[solar_plasma]

Still I am sure the keyword is electrical contact in my case.

The first 3 batches of AR were barren at any time, hot, cold, fresh or spent. Of course I filtered them and I cannot tell if there was cemented gold between the iron oxide which went back to the values. First when all visible basemetal has been dissolved, the 4th addition of AR gave strong positive in no time.

This was quite an interesting experience, since I ended with having all values (exactly as much as expected) in a quite small volume of liquid. Amazing stannous! I was blind, but now I can see!

edit: And the visible gold plating remained almost untouched before the 4th addition.

 

[Anonymous]

With some plated metal components you can actually run the AR for 15 minutes in full reaction, pour it off and neutralise the Nitric and get the majority of your values in that solution. Then you can run a clean batch of AR on the remainder of the product to catch the rest whilst it also digests all the base metals.

If you stannous test the original solution after a short time reacting it's as black as the ace of spades because all the surface gold is coming off first. If a little bit of base metal is exposed, the whole solution doesn't suddenly stop digesting the rest of the gold.

It's one of those things you learn to a greater depth, the more comfortable you get with AR.

 

[solar_plasma]

I do not doubt your observation. But I do not doubt mine either. So, obviously my case is a phenomenon or an artefact, that is needed to find an explanation for.

Why did all the first three solutions test negative, hot, cold, fresh, used? (well, "fresh" means still nitric, but after the first strong reaction - I did not test under the strong reaction)
Why have I been left with golden parts like the hole gold pins and the basis that is soldered to the silicon chip when most of the base metals were dissolved?
Why did I get all the gold I had calculated (it was mostly one model, so I could find it in yield tables)?

 

[Geo]

Did you wait for the reaction to stop and then test the solution just to learn the solution was negative? If you decant while the reaction is still in it's vigorous state, it should contain gold. When the nitric acid is depleted, there is nothing to hold the gold in solution. If the reaction stops and the the solution is still warm AND the nitric acid is used up, the gold will cement out faster than you can lift the container and pour out the solution. Because the pins are iron based, the iron cements out the gold and the copper. I too have done what you describe and it only seems to happen when processing CPU's. As a matter of fact, I always give the advice to only use have the nitrate needed to process the whole batch and then wait for the solution to totally cool and decant the solution to another container and start over with fresh chemicals just for this purpose.

 

[solar_plasma]

If you decant while the reaction is still in it's vigorous state, it should contain gold.

That makes sense to me. I did test when the reaction calmed down, though there was still NOx present. Still, the thick shiny yellow gold parts, undissolved, dominated the picture till the end. As lately as after all basemetal were dissolved, the gold dissolved within minutes, too.

 

[Deano]

This is an example of a phenomena called contact passivation.

This occurs when two metals or metal complexes which are both individually reactive to a solution are placed in that solution whilst in physical contact with each other.

The material which is lower on the emf series for that solution will go into solution first.

The second material will not go into solution until all of the first material has been dissolved provided that the two materials stay in physical contact with each other.

In the case of gold plated pins in aqua regia the gold will start going into solution first as it is the only metal contacting the solution.

When enough of the gold has been dissolved to allow access for the solution to the base metal substrate the dissolution of the substrate takes precedence and the dissolution of the gold stops until all of the substrate has been dissolved.

At this point the gold will recommence dissolving.

Generally the precious metals are at the top of the emf series for most solvents with gold at the very top.

Deano