# CPU collection lot



## kjavanb123 (May 24, 2012)

All,

I just like to share with you the following lot that I acquired from a friend. It weighs 1013 grams, 38 pieces total, with the following order

3 pieces of IBM
12 pieces of VIA
5 pieces of IntelDX4
7 pieces AMD P75
2 pieces of IntelDX2 (486)
1 piece of IntelDX (486)




I am gonna process and post the result. After warming up the HCL, how would i know the nitric addition is enough?

Regards,
Kevin


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## Geo (May 24, 2012)

add in small increments and let the reaction of the nitric stop before adding more. cover the reaction with a watch glass or a glass saucer so you can see when the red NOx fumes are no longer being evolved. proceed this way until ALL the metal has been dissolved. if you stop short of this your values will cement out on any iron or copper left undissolved.


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## trashmaster (May 24, 2012)

and please do this outside and away from anything that might RUST.

be safe;;;;


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## necromancer (May 24, 2012)

anyone want to estimate the total may be ??


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## gold4mike (May 25, 2012)

2.2 grams


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## kjavanb123 (May 25, 2012)

Thanks all for your feedback,

I only have an estimate on VIR C3 processor which was 0.21 grams of gold powder. There are 12 of them in the lot, so I am assuming 12 x 0.21 = 2.5 grams?? Considering each of these CPUs were bought at $4 each, I will know how the profit if any will be made.


Here are just some photos of crushed Intel DX, DX2 and DX4s



Also separated the IBMs and VIR C3 processor which i am going to process separately.



Is this proper way of removing the back of the gold lid on CPUs?



Back of the IBM CPU after being removed with hammer to expose the golden wires



Now, I am at a crossroad here on which path to go, Steve, and some other members here suggested removing the base and silver with nitric, then AR the remain, but Samuel suggest in the video shown in youtube to dissolve the CPUs in AR.

I will keep you posted on result hope that helps out someone in the forum in future.

Kevin


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## gold4mike (May 25, 2012)

I've been using a two step Poorman's AR method for all ceramic CPU's. I use roughly half as much as I think I'll need to completely dissolve everything on the first step. 

Let it sit overnight so any gold that dissolved cements back out.

Test for values to confirm it's barren, pour off liquid.

Add water and HCl, then Sodium Nitrate in very small increments until everything has just dissolved. 

This ensures I don't use too much nitric and I'm precipitating from a much less dirty solution.


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## philddreamer (May 25, 2012)

Kevin, you should apply heat & remove the" silicon chips" so to make sure you get the gold behind them. Sometimes just runnunig them thru the AR doesn't remove them & gold stays behind.

Just a thought.

Take care!

Phil

correction: should read= "silicon chips" instead of "silicon lids".


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## kjavanb123 (May 25, 2012)

Hi Phil,

Thanks for the tip. I used hammer, and as u note from the pictures there are no golden wires around the corners of the rectangular of the gold lid back. I have double check them all to make sure nothing is left. But I am sure for bigger lots some sort of heat would be required.

Here is also the gold powder from sample D of my previous post. It was an Intel Celeron CPU. I will dry it tomorrow and weigh the powder and post it.


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## philddreamer (May 25, 2012)

Sorry Kevin, I made a mistake.  
I should have written "silicon chip", the ones inside the cpu's.

Phil


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## kjavanb123 (May 26, 2012)

philddreamer said:


> Sorry Kevin, I made a mistake.
> I should have written "silicon chip", the ones inside the cpu's.
> 
> Phil



Hi Phil,

I am not sure where inside the CPU, could u point it out in my pictures?

Thanks
Kevin


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## kjavanb123 (May 26, 2012)

All,

I leached the Intel 486 DX , DX 2 and DX4 series which were crushed into small pieces. I warmed it up to almost 80c, added nitric in 10ml increment then brown fumes are observed till no more, then another 10ml, till almost 160ml of nitric was used. vs. 460ml of Hcl. As you note from the pictures the gold is the last one to go into AR. 

Keep you posted soon.

First minutes into addition of HCL and warming up the solution



After some boiling and nitric addition



Gold being dissolved as the last metals to go into AR



Regards,
Kevin


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## philddreamer (May 26, 2012)

Its the "glass" chip right in the center, inside of the ceramic, where all the tiny gold wires are connected to. 
If you were to take one of the cpu's and heat it, then try prying it off, you'll see the gold behind the silicon chip. When you don't use heat at all, these chips tend to stick even thru AR, and you don't recover the gold behind them. I use heat to incinerate, thus getting rid of gunck & dirt, plus I remove the silicon chips while I'm at it. 

Phil

This was from some left over ceramic PP's; I ran them thru months later, and recovered more gold.
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=52&t=12845&p=130797&hilit=pentium+pro#p128797


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## kjavanb123 (May 27, 2012)

Phil,

Thanks for your tip on silicon part of the chip. I will double check the remaining CPUs I processed. I added almost 10 grams of SMB to the AR solution from processing 15 pieces of Intel 486 DX, Dx2 and DX4 series plus AMD 6. It has been 9 hrs since the SMB addition and following happened. I guess I have to wait for at least 12hrs or more? Also SMB addition should be the expected amount of gold correct? what happens when I add more SMB to the solution? Solution still test positive for gold, so I have to wait till stannous test negative then proceed with filtering and drying the gold powder.

Here are some latest photos
mixed of silver/lead nitrate from processing a bunch of Intel 486 DX series.



Gold flakes



Gold powder layer at the bottom?



Regards,
Kevin


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## Geo (May 27, 2012)

you dont filter gold powder. you should have filtered before you added SMB. if you added SMB and your still getting a positive, it probably means you have free nitric acid that is stopping the precipitation. you may add more, but only small amounts until you get a negative test.


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## kjavanb123 (May 27, 2012)

Geo,

I have filtered the AR solution before addition of SMB. Still result are positive for gold but not much in there, so I am going to wait for another 10 hrs or so make sure all the gold be dropped.

As for the silver chloride / lead sulphate mix from previous pictures, I tried boiling in water and nothing happened, so I assume the mix is not lead sulphate. I tried addition of ammonia to the mix and it seems to dissolve something as you can see picture below, so I am assuming the dissolved section was silver chloride. How do I drop silver from this new solution? Is this similar to purifying palladium salt where I add ammonia and stir wait for a 24 hr and filter add hcl to the remaining solution so the yellow canary pure Pd powder precipitate?

Here are the pictures of what i am talking

The mix powder of silver or lead salt



The mix being boiled in water and it seems nothing got dissolved hence no lead in the mix



Finally introducing ammonia 25% to previous solution and the color changed so I concluded part of silver chloride must have been dissolved
View attachment 1


After some stirring, there are some undissolved materials at the bottom, curios what it is.



Thanks in advance
Kevin


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## Harold_V (May 27, 2012)

kjavanb123 said:


> As for the silver chloride / lead sulphate mix from previous pictures, I tried boiling in water and nothing happened, so I assume the mix is not lead sulphate.


Lead sulfate is not water soluble. Lead nitrate is soluble in hot water. 



> How do I drop silver from this new solution?


You should be able to make a recovery simply by adding HCl. 



> Is this similar to purifying palladium salt where I add ammonia and stir wait for a 24 hr and filter add hcl to the remaining solution so the yellow canary pure Pd powder precipitate?


In my opinion, yes, it is similar. It might pay to get the professional advice of the more learned of the group, however. 

Harold


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## kjavanb123 (May 27, 2012)

Harold,

I followed purifying palladium method but I put a copper wire in ammonia silver solution immediately reaction started and produced some gray foam around 

Geo,
regarding the gold solution and free nitric in it, I kept adding SMB to it and got brownish fume for a second, it still positive for gold, should I proceed to nitric removal with steam bath? Or keep on adding SMB till I get negative for gold presence in solution?

Thanks
Kevin


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## Geo (May 27, 2012)

as long as your getting red fume when you add SMB then you have free nitric. at the risk of adding a lot of salt to the reaction, i would keep adding small amounts of SMB until no fumes are emitted. this will mean the free nitric has been consumed.


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## kjavanb123 (May 28, 2012)

Geo,

I have been adding a lot of SMB to the solution even in small increments and still getting the brownish foams as shown in the picture below, and solution still positive for gold??? I am faced with a solution more than 1000ml of gold and addition of SMB precipitate some brownish residue at the bottom but solution still very positive for gold. If I do steam bath at this point will I lose value? I don't think i added this much nitric to the solution in dissolving process.

Brown foams forming after addition of SMB to solution



Stannous result for the same solution after addition of almost 100 grams of SMB!!





Regards,
Kevin


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## Palladium (May 28, 2012)

Do you have a gold button to add to consume any free nitric?


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## Geo (May 28, 2012)

well, for sure its still got free nitric and also for sure its still positive for gold. you can evaporate the solution till it forms gold crystals. ive seen pictures on the forum of dry gold chloride. Hoke says to evaporate until the solution is very thick like syrup. then you will add hcl to re-hydrate it and then evaporate again. each time, it expels nitrogen dioxide. Harold would recommend adding a small gold button to the solution and warm it. you would wait until the reaction stops or the gold is consumed. either way may be something you have to consider because you obviously have used way too much nitric.


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## kjavanb123 (May 28, 2012)

Geo,

Thanks for your advise. The solution is now 1500ml, I tried steam bath it for almost an hr and only gray fumes comes out. In case I want to drop a gold button, can I use something else like copper rod it will consume some excessive nitric. Please kindly advise.

Also, at this point addition of copperas will help? I know my SMB is old and clumped up together.

Thanks and regards,
Kevin


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## Harold_V (May 28, 2012)

kjavanb123 said:


> Geo,
> 
> Thanks for your advise. The solution is now 1500ml, I tried steam bath it for almost an hr and only gray fumes comes out.


That's exactly as it should be. There's a considerable amount of water in your solution which must be eliminated before you can expel the unused nitric. If the vapor cloud coming off has any color, that would be an indication that you are evaporating too quickly. When the solution is condensed enough, it will become thick like a syrup, at which time you'd introduce some HCl. That expels some of the nitric, which you'd see as the familiar brown cloud. 



> In case I want to drop a gold button, can I use something else like copper rod it will consume some excessive nitric. Please kindly advise.


Absolutely not! The only thing you should add to the solution if you hope to consume the free nitric would be more gold. If you use a base metal, it will cement gold. That, too, would work, but it requires a perfect balance of base metal, so that the small amount of gold that would be cemented would then, in turn, be dissolved by the free nitric. Hitting the proper balance isn't likely, so don't go that route. Besides, you'd be introducing base metals to your solution that are in direct conflict with your objective, that of purifying the gold. Use a piece of gold, or evaporate properly. Both work well, and should be understood by you. 



> Also, at this point addition of copperas will help? I know my SMB is old and clumped up together.


I can't address your clumped SMB, but I used copperas in refining, although I preferred SO2 gas. Copperas is a good choice if you have any doubts. 

Harold


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## kjavanb123 (May 28, 2012)

Harold,

Thanks much for your input. I read some archived articles on the forum, and there was a suggestion to dissolve a tablespoon of SMB to 50ml of hot water and pour that to the solution. I just did that and just fizzling no more brown fumes or foams formed. I just gonna wait for another 24hrs test the solution for gold with stannous.

Thanks again for all your help
Kevin


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## kjavanb123 (May 28, 2012)

All,

Thanks for your advices. I finally resort to zinc addition to the AR solution. I remembered when pushing the mixed PGM powders from the AR solution we used zinc. So I tried this with gold in AR and since I tried to rinse the remaining brownish powder with HCL and got no reaction I could guess this is the gold powder stuck in AR solution which I had issues dropping it with SMB.

Here are some photos.
Brown precipitant after zinc addition to the AR solution containing gold and SMB hence the sulfur smell from the reaction.



The same brown gold powder being filtered and to be processed using the methods described by Harold to purify.



I checked the liquid left from filtering and tested negative for gold. I really enjoyed this learning experience. I am always thankful to all members here who have helped me through.

Regards,
Kevin


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## Geo (May 28, 2012)

thats still very contaminated. your only half way there. now is the time to dissolve it again, but this time you can do it without AR or even nitrates. you should incinerate, but because we are expecting it all to dissolve anyway, it is ok to skip that this time. put the material in a clean container like a scratch free beaker or coffee pot. no heat is needed for this reaction. add 50 or so ml's of hcl to the material. add 10 ml's at a time of house hold bleach and stir.WARNING : chlorine gas will be emitted so do this outside and dont stand over the reaction. look at the material after a couple of minutes,if there is solids add another 10 ml's of bleach and stir. it should only take a few bleach additions to dissolve it all. no need to expel nitric or evaporate. let the solution sit uncovered in a safe place for 24 hours to let the chlorine to gas off. dilute with 2X water and add SMB and stir.

enjoy.


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## kjavanb123 (May 28, 2012)

Oops,

I went ahead before Geo suggestion, rinsed the brown powder in filter into beaker, followed purifying procedure. Boil in water 3x, decant, boil in muratic 3x decant grayish stuff, now I am left with gray powder, no sign of brown gold power I started with. What the heck just happened??? Thank God I only did this on a 100ml sample.

Thanks
Kevin


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## Geo (May 28, 2012)

did you keep the wash solution? the material still contains nitric acid. you cant wash it out, it has to be incinerated. when you added hcl you made a weak AR solution. test your hcl wash and see if you get a positive.


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## Harold_V (May 28, 2012)

I would have recommended that you not use zinc, but copper instead. That way you wouldn't have cemented any copper that may have been present. 

I would also comment that in Geo's post, he failed to make mention that before your solution was to be precipitated, that filtration is a requirement. Otherwise you recombine unwanted particulate matter with the precipitated gold, defeating the purpose. I make mention because some readers may not be totally familiar with what's being done, and could get the impression that filtration isn't required. I had a standing rule---no value bearing solution was to be precipitated without being filtered first. 

What has happened can be best revealed by you doing proper testing. Each of the solutions that are involved must be tested, to verify what they contain. The remaining material (the solids you mentioned) may be silver chloride, although I have no way of knowing if that's the case, or not. Silver chloride is soluble in ammonium hydroxide, so a tiny sample can be tested to see if it dissolves. If it does, it can be recovered by the addition of a little HCl. Testing is everything. No one should refine unless they have a firm understanding of the procedures. Otherwise, you work in the dark and have no idea where your values are, or if you even have them. 

A report on your findings would be interesting and constructive.

Harold


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## kjavanb123 (May 29, 2012)

All,

I still do know what went wrong here, the sample taken from solution is positive for gold, I added zinc powder it foams up, after few additions, I checked the solution and negative for gold, so I filter the brownish mud, add water, boil 3 times, decant, test the decant solution and no sign of gold in it, so I wash and boil 3 times with hcl, no color change, but everything clumps together and the dark brown I started turn into gray mud. I add some peroxide at room temperature and the gray mud comes to the surface and solution is reacting, I filter the gray mud and check the green/yellow liquid and no sign of gold.????

I am going try Geo tip on dissolving the dark brown mud from zinc precipitation in hcl + h202 at room temperature.

Thanks
Kevin


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## kjavanb123 (May 29, 2012)

All,

I am still confused about what went wrong with process. Here are some more testing on samples.

This time i followed Geo's advice. I removed 40ml of "troubled" AR solution, added zinc, precipitated the powder as you can see in the following



Tried to dissolve the above in AP at room temperature, reaction started but the remaining powder just cling together and just stayed on the surface as u can see in the following picture.



So i filtered it, and tried to dissolve the cling material in AR, and it produced this 2 greenish buttons that just won't dissolve even with heat????



This is the only brown powder left from the "troubled" 1500ml AR solution which i have been trying to purify further.



The powder prior to water washing



Your comments are welcome. I stuck a piece of copper wire in the remaining 1500ml solution to see what is going on.


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## Geo (May 29, 2012)

kjavanb123 said:


> I am going try Geo tip on dissolving the dark brown mud from zinc precipitation in hcl + h202 at room temperature.



actually, it was hcl and bleach. hcl/Cl leach. it dissolves gold foils and gold powder very well.

if you precipitated with zinc, the precipitate will be contaminated with the zinc. straight hcl can remove this.

im sure by now you understand this all happened because you had too much nitric in your reaction. to avoid this in the future, only add nitric and small increments only until the material is dissolved. it saves on chemicals, reduces waste and helps when precipitating.


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## kjavanb123 (May 29, 2012)

Geo,

Thanks for your help. I stuck a copper rod and iron rod into the "troubled" solution, but purified the remaining brown powder according to instructions here in this forum and it is on process of being dried. I will keep you posted on that situation.

Instead of nitric addition, when re-dissolving the gold powder I used hydrogen peroxide ( AP method ) and it worked out just fine, just few drops of water to rinse it, and added SMB to the solution immediate gold precipitation occurred. So this new batch of 5 Intel Pentium MMXs I just added enough peroxide to hot hcl till no more bubbling and fizzing occurred. So after the beaker reach the room temperature I will decant it to another beaker which holds ice cubes, drop some sulfuric acid and wait for any sulfates or chloride deposits, filter the solution clean, try to add SMB to it hopefully this time I won't have any problems.

I am still confused what to do with my "troubled" AR solution from previous batch, it still shows gold in it, I stuck this rod into it and few hrs later some brownish mud stuck all around it.



It has been a great learning experience for me in gold refining,
Thanks all
Kevin


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## tek4g63 (May 29, 2012)

Sorry to but in on your topic, but this sounds like a pretty big mess. And unless I have missed something, there has been a lot of missreading of information and a bunch of trying crazy things witout asking first and waiting for direction. You don't have to get in a big rush, as long as you don't throw anything away your gold will still be there waiting on you.

I have a growing collection of ceramic CPU's that I plan to process one day and when I do you can rest assured that if Geo,Palladium, or Harold take the time out of their day to instruct me then I will take all of their advice and wait till questions have been answered before moving on. I'm happy to see that they and many others are giving up their time to help you and I wish you a sucessful recovery of your values.


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## kjavanb123 (May 29, 2012)

Hi Tek,

Thanks for your support. I have been following instructions, I messed up in removing excessive nitric, so I let the messed up AR solution to sit there for a while till I fix its problem. My experiments with PGMs and catalytic converters have been really great help to find my way in gold recovery from CPUs which is a lot easier it seems.

Here is another picture show of new batch, Intel Pentium MMX, there are 5 of them, you need to warm them up a little and the silver color lid will just come off with a tap.

Intel Pentium MMXs ready to be leached using AP method.




CPUs inside a beaker of warmed up HCL.



Introducing hydrogen peroxide 25% to the above solution and immediate reaction begins.



AP solution after an hour of heating and addition of peroxide in 10ml increments till reaction slows down.



This is stannous test on AP solution after almost an hour and half. I noticed addition of hydrogen peroxide doesn't produce as much as foams as it did and also the tiny little gold foils that used to float on the surface completely dissolved. Another sign that leach is complete.



Regards,
Kevin


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## tek4g63 (May 29, 2012)

Mmmmmm thoes look good even when being cooked. Lol. 

I wish you success on this next batch and I hope that it all goes a lot smoother for you. I will be taking notes along the way, so please don't spare on the details.


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## kjavanb123 (May 29, 2012)

Tek,

This forum is all about helping each other, and as we all say you get what u give, I owe whatever I have learned in practice to members here Steve, Lou, and many others who take time to share their expertises. 

The Intel Pentium MMX batch went pretty well, I dropped the silver/lead but noted that dissolving gold foils on chips is not complete so i ran another AP on them and gonna be added to my already cooled off AP solution. I have used AP ( aqua peroxide ) on palladium and it dissolves it at room temperature, but with gold I noticed you have to refresh your warm hcl before adding any increments of peroxide so the dissolving gold becomes a lot quicker. I kept adding small amounts of peroxide and foams were made, but after they settled still could see the golden foil stuck to the chip, as soon as I added couple drops of hcl to the beaker, and waited for a few mins for it to reach the same temperature then added a drop of peroxide the same fuming and foaming takes place but once settled a large portion of the same gold foil on chip was dissolved. So this might be something to take a note. I remember the ratio of Hcl to H202 in AP was like 10:1, so it won't hurt if you have more muratic to begin with.

I will post more pictures as I finish up this batch.

Regards,
Kevin


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## Geo (May 29, 2012)

even though your using peroxide, im not sure the method your using it can be described as AP. though technically it is, not many members use peroxide with the express intent of dissolving gold. 25% peroxide will definitely do the job, but i have to warn you. heating hydrogen peroxide that is that concentrated is playing with explosives, literally. the fumes can decompose violently.if its working for you and you dont mind the risk then who am i to complain.


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## samuel-a (May 29, 2012)

It a shame i haven't seen this post earlier...

Kev, 
You have learnd the painfull lesson of too much nitric in you AR. With the risk of sounding like an old p****, had you followed the strict regime in regards to nitric addition, non of this would have happend.
You have done great by sharing your process and observations, I hope your experience will also help someone else trying this for the first time.

With that said, there are few solutions to such kind of a mess, here are the two i have found to be most effective in such case:
Urea would be my no. 1 choice - yes, i know it's not so popular around here, but Urea is a great tool to have when you mess up. Since the solution is so diluted, but still dissolving precipitated gold, i makes little sanse to try and evaporate it.
To kill free nitric with urea, warm up the solution, just warm to the touch, say 85-93F. Add few prills of urea and observ how do they react with the solution, meaning, is it very rapid? does it fizz like crazy or calmly... this will somewhat help to approximate if you have planty of free nitric or just a little.
If you have found that indeed an excess of nitric is present, add the urea prills incrementally and in a decreasing manner at each addition. Mix well between each additions until there's no more fizzing and the prills are slow to dissolve.
After that treatment, precipitation should be proceeded with no special events.

Another method, would be to simply warm up the solution to 158-176F and pour in a solution of warm water + SMB and letting the AR to re-dissolve the newly precipitated gold. Repeat that process until the gold does not re-dissolve. Add constant stirring if possible.
It is similar to Harold's and Geo's suggestion from earlier in this thread, the only diffence would be that instead of adding gold from an outside source to consume the nitric, you are consuming it with the same gold over and over again.
This may be time consuming either way, but with this method, you get huge surface area to react with the dilute AR, so it will probably be quicker.
A gold bottom is great for when the AR is concentrated. IMHO.

To conclude, i hope this experience will not discourage you from attampting this process again for ceramic cpu's, as it is fast and cheap.
By now, with the help of the members here, i'm sure you know what to avoid and how to handle yourself if things head south.

Good luck with your next project.
Sam


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## Palladium (May 29, 2012)

Maybe this was just an experiment I don't know but I would recommend precipitating your gold in a beaker instead of a flask. You should dry your gold in the beaker it was precipitated in instead of washing it into a filter where some will be trapped and lost until later recovery when the filters are processed.


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## kjavanb123 (May 30, 2012)

Geo said:


> even though your using peroxide, im not sure the method your using it can be described as AP. though technically it is, not many members use peroxide with the express intent of dissolving gold. 25% peroxide will definitely do the job, but i have to warn you. heating hydrogen peroxide that is that concentrated is playing with explosives, literally. the fumes can decompose violently.if its working for you and you dont mind the risk then who am i to complain.



Geo,

I have a glass on top of the beaker as soon as I add the 25% h202 to it in 10ml, so most of the fumes are back into the solution. But this avoid dealing with nitric and drop of gold from this method was instant and fast. 

Thanks for your help on this experiment.

Kevin


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## kjavanb123 (May 30, 2012)

samuel-a said:


> It a shame i haven't seen this post earlier...
> 
> Kev,
> You have learnd the painfull lesson of too much nitric in you AR. With the risk of sounding like an old p****, had you followed the strict regime in regards to nitric addition, non of this would have happend.
> ...



Sam,

I really have to thank you because if it wasn't for your video of processing old CPUs I wouldn't even start this. So thanks for sparking the idea in my brain :lol: 
In regards to your suggestions, I have saved the solution that was messed up and it is still positive for gold, but got 2 grams of it already dried and purified. As you can see from the picture below, 



I am going to follow your first suggestion and post the result, hopefully someone else might actually avoid the mistakes I made.

Thanks again all,
Kevin


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## kjavanb123 (May 31, 2012)

Hi,

Second batch consists of 5 intel pentium MMX which were dissolved in Hcl and hydrogen peroxide after filtering and dropping silver compound from the solution, filtered it, dropped SMB to the solution first spoonful didn't produce any brown foams but second addition of SMB produced some brownish foams, what that could be? 

Thanks
Kevin


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## philddreamer (May 31, 2012)

Kevin, why are you adding SMB to the AP solution? Did it test positive for gold? AP doesn't hold gold in solution because it usually is saturated with base metals, copper in particular. Also, silver dissolved in AP!?

Phil


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## kjavanb123 (Jun 6, 2012)

Phil,

I had no idea about AP or AR leach would require different agent to drop the gold, so I just used SMB. what else should i have used for AP leach? I checked the solution and is negative for gold, but the brownish fine powder is at the bottom which i have to purify today and post pictures.

Thanks and regards,
Kevin


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## philddreamer (Jun 6, 2012)

Hi Kevin!


> what else should i have used for AP leach?


Clean copper!
As we have mentioned before, gold doesn't stay dissolved in an AP solution because the AP is saturated with copper & gold WILL NOT stay in solution; it will cement. Unless you add too much peroxide AFTER all the copper has dissolved, the excess of peroxide will dissolve some of the gold foils, then maybe some gold will be in the AP solution. Testing with Stannous Cl will reveal if there's any present; then you will just add some more copper, thus cementing the gold. 
AP is mainly a process for recovering gold. AR is more for refining the gold.


> I checked the solution and is negative for gold, but the brownish fine powder is at the bottom which i have to purify today and post pictures.


Yes, the solution will very likely test negative; the gold will be the dark sediment at the bottom. This will be refined for higher purity. This is when you'll be adding SMB. (You could add copper to cement the gold, but that's not adviced when you are REFINING.)

You should re-read the instructions on AP (& also AR), so you you can pick up more details of the processess & have less troubles on next batches.

Kindly, 8) 

Phil


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## kjavanb123 (Jun 6, 2012)

Phil,

Interesting enough, the last purified brown gold powder you see in the picture, was produced by re-dissolving the powder in AP, after being washed with water and ammonia and hcl 3 times, and dropped by adding SMB, I even checked the remaining solution from that and it was negative for gold. 

So you are saying I should just stick a copper wire into the current AP gold solution to collect the remaining gold?

Thanks and regards,
Kevin Jones


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## lazersteve (Jun 6, 2012)

kjavanb123 said:


> Phil,
> 
> Interesting enough, the last purified brown gold powder you see in the picture, was produced by re-dissolving the powder in AP, after being washed with water and ammonia and hcl 3 times, and dropped by adding SMB, I even checked the remaining solution from that and it was negative for gold.
> 
> ...



Kevin,

Acid Peroxide has several uses as you well know.

One use is to use it to dissolve the bulk of the copper from escrap to release the gold foils from the scrap. When used in this manner sometimes a little gold gets dissolved in to the solution. Simply add more copper to cement out the traces of gold from the high copper concentration solution. The gold will be a dirty black color and need to be refined a second time to bring it's purity up to par.

The second application of Acid Peroxide is to dissolve the foils and gold powder for the second refining. In this instance the gold is mostly pure and free of base metals so it is best to precipitate the dissolved gold using SMB or copperas. Using copper to cement the gold in this instance actually works to contaminate your gold again with the copper you are using to cement. This defeats the purpose of refining the gold and is counter productive.

I hope this clears up the multiple uses of AP and the means by which dissolved gold is recovered from the various solutions.

Steve


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## kjavanb123 (Jun 7, 2012)

Steve,

Thanks as always for being such a help. I figure out for my next batch which is going to be 12 VIA gold lid chips I remove most of the base metals with a nitric leach, wash and decant with water, then proceed with AP leach in order to avoid getting involved with excessive nitric, that way I can drop all the gold using SMB.

Here are some latest photos of discussed project.

Gold powder being dissolved in AP, without heat, then filtered and ready to be dropped using SMB.



Few seconds after addition of SMB to the above solution



Few mins later after addition of SMB to the gold AP solution



Also during the purifying process for gold powder, in section of addition of ammonia and heat, the following residue was produced which i decant in a different jar, it had a layer of brownish cloud right in the middle of solution, so i added hcl to it and all the brown stuff disappeared, how can i know if this was silver?



Regarding the Intel Pentium 486 DX series project, which the solution even after addition of excessive amount of SMB tested positive for gold, I dropped in an iron rod, and after a week this following residue is filtered and solution tested negative for gold, so I assume this iron rod took down any gold in the solution with it, so I need to purify this mix. Please advise.


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## samuel-a (Jun 7, 2012)

kjavanb123 said:


> so I need to purify this mix. Please advise.



Kev, if you think there's gold in this sludge, proceed as follows:
Dry
Incinirate
Digest with dilute nitric (test the leach for silver with HCl)

The undissolved solids will be gold and some left over ashes. Then dissolve the gold with whatever leach you are comfortable with.


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## maynman1751 (Jun 7, 2012)

> Regarding the Intel Pentium 486 DX series project, which the solution even after addition of excessive amount of SMB tested positive for gold, *I dropped in an iron rod*, and after a week this following residue is filtered and solution tested negative for gold, so I assume this iron rod took down any gold in the solution with it, so I need to purify this mix. Please advise.



THis is where you should be using copper to cement-*not iron*. By using iron you also dropped out the copper. If you had used copper, only your values would drop (plus some dragged down contaminants). Your sediment would be much 'cleaner' and easier to clean up and a lot less of it. Your way will still work, but adds a lot more base metals to the mix.


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## lazersteve (Jun 7, 2012)

A note of caution using highly reactive metals to clear left over acidic solutions of SMB and SO2:

If you do not heat the solution to drive out any excess SO2 present before cementing, there is a very high probability of forming the deadly gas H2S (hydrogen sulfide). The gas smells of rotten eggs (50% of the population can't even smell it) and is as deadly as hydrogen cyanide. The gas is formed when sulfurous acid (SO2 with acid in water) is combined with a metal higher than hydrogen in the activity series (iron, aluminum, zinc, tin, etc). Check my website documents for information on sulfurous acid and the activity chart.

For the above mentioned reasons perform this reaction in a good fume hood or in a very well ventilated area.

The brown sludge is a mixture of base metals and their sulfides formed by the in situ reaction of sodium and hydrogen sulfides from the excess SMB solution and the iron you added. This is also the cause of the false positive (brown) reaction one gets when testing a strongly sulfurous solution with stannous chloride. Incinerating the brown solids will produce a strong sulfur odor and other toxic sulfur gases. Adding acid directly to the brown solids will also regenerate the H2S. 

Please read the entire wiki article on hydrogen sulfide and the above referenced documents from my website.

Steve


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## kjavanb123 (Jun 7, 2012)

All,

Thanks for your input on the copper / iron incineration process, i filtered the black residue poured it in a flask, and dropped in some dilute nitric to it as u can see in the picture below,



But some residue is still undissolved, should i try dissolve them with sulfuric or hcl??

Best regards,
Kevin


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## kjavanb123 (Jun 7, 2012)

Just one more thing, I got another lot coming up containing 12 pieces of VIR gold lid cpus and 3 IBM gold lid chips, and I don't wanna mess up, so I am gonna follow the following instruction which will be a brief of what I learned from this project and post.

1. Try to expose as much as areas of visible gold wires or foils by crushing the CPUs
2. Dissolve most base metals in a nitric leach.
3. Wash and decant with water
4. Pour the nitric solution into a beaker with ice in it to bring the solution temperature down and add sulfuric acid to allow any lead or silver to be
dropped out of solution.
5. Dissolve the remaining CPUs in AP, in order to avoid nitric, then filter, and check for any remaining gold signs on CPUs, then drop with SMB.
6. Purify if needed, dry.

Thanks and regards,
Kevin


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## kjavanb123 (Jun 7, 2012)

All,

I followed your advise, and dried the undissolved section of solution of the brown mud in previous picture, after I added dilute nitric, but strange enough, I tested the greenish solution and it was positive for gold?!?!?! yet there are some undissolved residue at the bottom. This is really strange.

Here are the picture of solution after I added some nitric to it boiled it for few minutes.



And this is the stannous test result of the same greenish solution above.



I am going to remove any excessive nitric using the Urea methods mentioned here in the post, and try dropping the gold with SMB.

Thanks
Kevin


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## maynman1751 (Jun 7, 2012)

> A note of caution using highly reactive metals to clear left over acidic solutions of SMB and SO2:



Steve! Wouldn't the SO2 have left the solution after a week of setting? Was I correct in telling him to use copper in that instance instead of iron? Thanks, John.


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## kjavanb123 (Jun 8, 2012)

All,

After heating the saturated SMB solution which showed positive for gold yet not precipitated, I added Urea in small increments, got fizzing, till no more fizzing, then I added SMB into the solution and solution turned from green color to this light brown color as following



and closer shot,



So I am gonna wait till it settles, and also solution showed no signs of gold.

Keep you all posted
Regards,
Kevin


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## lazersteve (Jun 8, 2012)

maynman1751 said:


> ...
> 
> Steve! Wouldn't the SO2 have left the solution after a week of setting? Was I correct in telling him to use copper in that instance instead of iron? Thanks, John.



Not always the case. The solution itself will hold some free SO2 depending on many factors including dilution, pH, temperature, container geometry, etc.

As for using copper or iron, I always use copper to recover traces of values from my stock solutions that test positive with stannous chloride. After recovering the values via filtration, I follow the copper cementation procedure with a treatment of metallic scrap iron to recover the copper. The remaining solution is then filtered free of copper and neutralized with base for proper disposal.

Steve


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## kjavanb123 (Jun 8, 2012)

All,

3 pieces of IBM gold lid chips was dropped into nitric and boiled for 15 mins to remove the base metal, the indicating sign that nitric has dissolved all the base metals would be after addition of fresh nitric to solution, I get no more brown fumes, then i am gonna decant, wash with water, decant, and continue till after water addition doesn't change color. Pour the nitric solution into an iced beaker, drop some sulfuric to drop any remaining silver or lead sulfate.
AP the remaining CPUs and proceed with SMB.

Pictures are coming up.

Regards,
Kevin


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## maynman1751 (Jun 8, 2012)

After adding the sulfuric don't forget to filter to remove said impurities.


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## kjavanb123 (Jun 8, 2012)

maynman1751 said:


> After adding the sulfuric don't forget to filter to remove said impurities.



Thanks for your input. Nitric leach is almost done. This way I can actually recognize all the golden parts of CPU, follow by AP leach for the remaining part. 

Thanks a lot,
Kevin.


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## patnor1011 (Jun 9, 2012)

Incinerate between those two.


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## maynman1751 (Jun 9, 2012)

patnor1011 said:


> Incinerate between those two.



This be true! Or you could make AR and dissolve your values.


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## kjavanb123 (Jun 9, 2012)

All,

Thanks for your info on this. Here are some updates on my latest batch of CPUs, 3 pieces of IBM p150+ CPUs. 

1. Leaching the base metals using nitric for an hour



2. After second time dissolving the remains of CPUs in nitric till I got no more reaction or change of color for addition of nitric



3. After some major washing with water and decanting, I added hcl to the left over CPUs and gold foils, and drop the peroxide small increments, reaction 
started at room temperature.



4. half an hour into AP leach of CPUs, I got this white solids along with AP solution, what are they???



5. Finally the gold solution after the filter was washed with fresh AP to clean up any left over gold in the filter paper.



Everything looks good, but in case in order to avoid anymore mess ups, I gotta try a small portion of solution and add SMB to it to see what goes on. Even, I washed the remains after twice nitric leach with plenty of water and decant, for some reason i feel that white stuff are impurities that got into the gold solution. So please advise if anyone is familiar with that. 

Thanks and regards,
Kevin


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## rewalston (Jun 9, 2012)

You didn't incinerate your solids before you put them into AP, you can't wash nitric out with water, the only way to get rid of it is to incinerate. Then you can use AP to get rid of the rest of the base metals and salts.

Rusty


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## kjavanb123 (Jun 9, 2012)

Opps, 

Thank God i didnt do anything with gold solution yet, so according to Steve, I gotta drop all the impurities and gold by dropping a copper rod into the solution.

Regards,
Kevin


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## lazersteve (Jun 9, 2012)

Kevin,

Your pregnant gold solution is ready for SMB in my opinion.

The white powder in your second nitric run, is likely a yellow tungsten compound that easily dissolves in strong base solution. This stuff will foul up your beakers if you let it dry so clean them quickly after your filter out the nitric solutoins.

I can't help but notice your beaker is dirty that you are using to dissolve the foils. In fact it appears as though the walls of the beaker are coated with PGMs. You should always work with clean beakers and flasks when recovering and refining your metals to eliminate contamination from your previous works.

Steve


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## patnor1011 (Jun 9, 2012)

In my opinion to go from nitric leach to AP is at least unusual. I would dissolve foils in AR, filter, precipitate with SMB, wash and then run powder second time. Even thou you used AP you will have to run your powder second time anyway in order to get really pure gold so whole AP thingy was just waste of time and chemicals IMHO.


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## lazersteve (Jun 9, 2012)

Pat,

Once the base metals and silver are removed with nitric acid, the method by which you dissolve the foils is pretty much arbitrary in my opinion. I routinely use AP to dissolve recovered foils and fine powders. I also use it to dissolve PGMs on occassion.

If I have a large amount of wet gold powder, metallic gold over 18kt, or chunky dried gold powder, aqua regia is my first choice for dissolving the gold.

The keys to obtaining pure gold are removal of the base metals and silver, proper wash processes, attention to detail when cleaning glassware, and good melting practices. 

I use nitric acid before dissolving the recovered gold when I'm interested in recovering the silver.

Steve


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## patnor1011 (Jun 9, 2012)

Wouldn't be HCl/Cl better cost-wise than AP? Well for me it may be better as I can get 3l of bleach for price of 0,1l H2O2.


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## kjavanb123 (Jun 10, 2012)

Edited

That is all i gotta say, I was trying to upload a picture despite being frustrated at this latest batch and gold percipitation which really edited me off.
I leached 3 pieces of IBM chips that were gold lids all the way, per my previous post, I leached twice using nitric washed and decant with water, then did AP on the remains. It produced yellowish solution plus some white powder, which was filtered, then I added fresh AP to the filter that completely dissolved any gold stuck in the filter paper. Thinking this massive looking IBM CPUs would have at least 0.2 grams of gold, not less, i was expecting at least 0.6 grams of gold powder, after I dropped SMB into the gold solution, waited for 30 mins, and as you can see from the pictures it turned brownish, and some gray color percipitant formed at the bottom of beaker, I washed with water, boiled it, and decant still no color change, I added one round of ammonium wash, nothing happened to the powder, then i added hcl to it and boiled, it seemed majority of it got dissolved in hcl and nothing left at the bottom of beaker. nothing?!!!!? I really got mad at this point I don't know how others do it, it really messed up.

Gold solution this morning after being sitting there for 12 hrs



Immediately after addition of SMB



10 mins after SMB addition



After 30 mins of SMB addition, there was this dark grayish percipitant at the bottom of beaker, and solution negative for gold



After adding water , boiling and decanting for 3 times, this grayish color percipitant showed at the bottom, added ammonia, boiled, and decant still there, but as soon as I added hcl to it boiled it, it was all gone, it seemed like the powder was dissolved in hcl and ammonia. I don't know where the gold went.

Regards,
Kevin


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## necromancer (Jun 10, 2012)

do you have a grand total gold content for the:

3 pieces of IBM
12 pieces of VIA
5 pieces of IntelDX4
7 pieces AMD P75
2 pieces of IntelDX2 (486)
1 piece of IntelDX (486)


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## kjavanb123 (Jun 11, 2012)

Hi,

I processed them in separate groups. But 8 Intel DXs series resulted 2 grams. Considering part of it was lots due to mess up. I will post more data for other CPUs soon.

Regards,
Kevin


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## kjavanb123 (Jun 11, 2012)

Here is also a snap shot of latest recovering the lost gold powder during processing the IBM series. It vanished right after ammonium addition, but somewhat it showed up as this dark grayish color, which i redissolved in AP.

Now the new AP gold solution



After SMB addition



And finally that gray precipitant changed into the brownish color gold



I hope this pictures and details become useful for others trying to do same projects.

Regards,
Kevin


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## tek4g63 (Jun 11, 2012)

I don't want to be a wet blanket, and I know that you are in no mood for this, but I'm very interested in this whole thread and I don't want it to go sour. With that said, you may want to edit your last post with the pictures in it for language. I don't know how strict Harold is on certain words but if it was me I wouldn't want to chance it. 

I hope to see you get to the bottom of the problem with this last run, I'm on the edge of my seat! Good luck man, I wish I could be more help.


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## kjavanb123 (Jun 11, 2012)

Thanks for ur info. Incineration after nitric leach, can someone tell me in simple Language how is done?

Regards
Kevin


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## necromancer (Jun 14, 2012)

this topic continues here:

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=38&t=1997#p146478

would be nice to have this post in one post and not ... 2...or more


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## kjavanb123 (Jun 18, 2012)

sorry about the reposting. I have a question regarding ammonia. Once trying to dissolve silver nitrate in ammonia, and the same time my AR was working on CPUs lots of white smokes came out of AR beaker?? how is this related to ammonia nearby?

Regards,
Kevin


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## Geo (Jun 18, 2012)

thats white ammonium chloride "smoke". its tiny airborne crystals of ammonium chloride. when ammonia and hcl come into close proximity of each other, the vapors from the hcl will cause the white crystals to form in the air.


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## kjavanb123 (Jun 19, 2012)

thanks Geo for your comment on ammonia and hcl which produces this nasty smoke that halt most of my operations. So next time I don't use ammonia anywhere near hcl.

This is last pieces of CPUs for this lot I have had, sadly i didn't get any gold for these big IBM CPUs maybe 0.2 grams I still don't know what went wrong. using nitric leach then AP leach.

Here are the following and last items in the lot, VIA chips, last time i processed one of them produced 0.2 grams of gold powder, so 6 of them would produce 1.2 grams. I just leached them in AR.



I heat them in hcl while adding small increments of nitric, I do this till I get no more reaction or brown fumes from nitric addition.

These are some pics from the AR leach on these CPUs.

After AR leach was completed. I tried to use the minimal amount of nitric to avoid further problem during SMB gold drop.




they look pretty clean once inspected closely. Now after i decant the solution into another beaker with ice and drop sulfuric acid, is it known how much sulfuric is needed to drop all the lead/silver from the solution? 


Regards,
Kevin


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## philddreamer (Jun 19, 2012)

Just a few drops of sulphuric for the lead will do, Kev. For the silver, some tap water; the ice might have done this already, if it was from tap water. 

Take care!
Phil


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## kjavanb123 (Jun 19, 2012)

Phil,

It was tap water ice at the bottom of beaker, however I think the filtered white powder mostly to be lead salt, as I didn't see any MMCs with this type of CPU.

Thanks and regards,
Kevin


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## Geo (Jun 19, 2012)

the silver in this type CPU is in the braze that welds the lids to the body and also the braze that welds the legs to the body.


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## kjavanb123 (Jun 19, 2012)

Geo,

Interesting point there. I just had an issue with gold precipitation after I filtered the lead/silver salt from the solution, I tried to test if there is any excessive nitric in the AR solution, so I dropped in few crystals of Urea to the warm AR solution and got some fizzing immediately, so I added till fizzing slowed, added some water, and this time instead of SMB I used copperas, added a spoonful, stirred, it foams up, so I add another spoonful, its foaming settled, and half spoon later no more foaming, so I stopped, the color of solution darkened a little bit, but in case I didn't mess up I dropped in another copper sheet to the solution so if there is anymore gold in the solution it cements on copper sheet.

Pics coming up later.

Kevin


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## necromancer (Jun 19, 2012)

why do you leave your cpu whole?

everyone i see breaks them and makes sure the centre is smashed out


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## kjavanb123 (Jun 19, 2012)

Necro,

I smashed the graphite part in the back which covers the back of gold lid, but I don't have access to a torch at home, so I leave the gold lid as it is. Now that CPUs are processed it is easier for me to remove the gold lids to see if there are anything behind.

Regards,
Kevin


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## kjavanb123 (Jun 20, 2012)

For all you following this post, and interested, I finally cemented the gold powder from the AR solution of 6 pieces of VIA CPUs. It looked good, I really don't know what helped, copperas? the SMB? or copper sheets? Since most of the copper being removed from the sheets, I assume that copper did the job of dropping the gold from AR solution and not the SMB or copperas. Your comments are needed on this.

Here is the copper sheet, along with the contaminated gold powder at the bottom.



The same gold powder going through the purifying process, everything looked good after 5x boiling in water, followed by 2 times in ammonia which stick the gold powder together, then 1 time hcl boil. It's being dried as I am posting this. picture and total weight of dry gold powder for 6 VIA CPus will be posted soon.



Thanks all for your support through this post, I have learned a lot more about gold refining.

Kevin


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## kjavanb123 (Jun 21, 2012)

All,

The finale of my lot #1 processing. I am sure I have lost some amount of gold during the process since it was my very first time in gold refining. The completed dried auric chloride salt weighed 2.567 grams, and the gold button which was produced by putting the gold powder in a lab scale electric furnace weighs 2.566 grams so 0.01 grams of it must have been chloride.

I have another lot, lets call it lot#2, which i will process, this time using what i have learned from this lot processing. Thanks for your help on this post, and I just hope someone might find this post interesting and useful.

The final of 24k gold button produced from the list of CPUs I mentioned in my first posts, but I consider this gold weight as the lowest you can extract from this chip sets.



reg,
Kevin


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## necromancer (Jun 21, 2012)

kjavanb123, so you got, 2.566 grams from your:

1013 grams, or 30 pieces

3 pieces of IBM
12 pieces of VIA
5 pieces of IntelDX4
7 pieces AMD P75
2 pieces of IntelDX2 (486)
1 piece of IntelDX (486)
-----------------------------

in your original post you state you have 38 pieces, i only count 30 in your list


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## Geo (Jun 21, 2012)

that weight is low for the CPU's you processed. you still have gold somewhere, either in solution or on the material.


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## kjavanb123 (Jun 21, 2012)

necromancer said:


> kjavanb123, so you got, 2.566 grams from your:
> 
> 1013 grams, or 30 pieces
> 
> ...



Well, the following were in the lot too, which i didn't process 

3 pieces of MMX Intel, silver lid
1 piece of Celeron Intel, silver lid
1 piece of 9921 AMD
1 piece of Athlon, AMD
1 piece of 256 Intel

So these I haven't processed yet, and I know I messed up on IBM chips which were holding more gold than the rest. I practically lost all the gold in there, during the AP leach. But I have learned a lot from processing this lot.

I have another lot which i will share the info on that in another post.

Regards,
Kevin


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## kjavanb123 (Jun 21, 2012)

Geo said:


> that weight is low for the CPU's you processed. you still have gold somewhere, either in solution or on the material.



Geo,

I know it's too low, cause I practically got nothing out of 3 IBM gold lid chips, and 6 of the VIA chips I processed produced only 0.5 grams of gold, i did the same chip first only one of them produced 0.2 grams of gold powder?! So I must have lost the gold content somewhere down the road during different leaches.

I have another lot mostly intermediate CPUs and ceramic types, which i will process soon, using the knowledge i gained on this lot. Basically, this 2.56 grams of gold would cover the CPUs purchase costs and a little extra money. what did u estimate the gold content of the list i mentioned would be if processed correctly? I was expecting 4 grams.

How about the following instruction to process next lot?

1- Dilute nitric leach to remove base metals including silver
2 -Decant, add water, boil, decant, repeat few times
3- Add hcl and boil, add nitric in small increments to dissolve gold foils
4 -Drop the gold with copperas, or can I use copper sheet to cement gold?

Regards,
Kevin


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## Geo (Jun 21, 2012)

nitric acid has a hard time dissolving iron. it can, but theres a easier way to deal with ceramic CPU's. samuel-a has some videos on the entire process. when i do ceramics, i follow his instructions as best i can and i have always had success. 

break the chips in 4-6 pieces.
place pieces in a beaker and add hcl and warm.
add nitrate in small increments.add and wait till the red fumes stop and add more.
continue the dissolution until all metal is dissolved, do not add more when you cant see any more metal. filter while warm. 
test solution with stannous chloride to assure the presence of gold.
let solution cool and add a few drops of dilute sulfuric acid to precipitate the lead.
add solution to ice so the solution will chill.this serves two purposes, it allows the silver chloride to precipitate and dilutes the solution.
when the ice melts,filter all white precipitate from solution.
add solution to the vessel you precipitate your gold in and add the precipitant of your choice.
be sure to test the spent solution with stannous chloride.


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## kjavanb123 (Jun 22, 2012)

Geo,

This procedure is exactly what I have used on 2 different ceramic chips, and since I must have used some excessive nitric during leach, I had to deal with loss of gold during precipitation. Now, can copper sheet be a more trouble free precipitant than smb or copperas?

Thanks
Kevin


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## Geo (Jun 22, 2012)

you can use copper to cement values, but it will cement every thing lower than copper (gold, silver, palladium) plus you will have some of the copper in the powder. if you want a rough recovery then it should work fine but keep in mind that cementing is not considered refining, its strictly recovery. the resulting powder will have to be refined.

of coarse, after you get the contaminated powder, you can dissolve in hcl/Cl. it is much more forgiving than AR but only works well on foils and powders.


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## qst42know (Jun 22, 2012)

> 3- Add hcl and boil, add nitric in small increments to dissolve gold foils



Are you forcing your reactions by running too hot? 

In an open top vessel actual boiling is best reserved for when the gold is safely on the bottom. Otherwise you may be spraying considerable values over the top.

When gold is in solution don't boil, just gentle heat.


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## kjavanb123 (Jun 23, 2012)

how do i delete a post?


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## kjavanb123 (Jun 23, 2012)

qst42know said:


> > 3- Add hcl and boil, add nitric in small increments to dissolve gold foils
> 
> 
> 
> ...



qst4,

Indeed, that word should have meant gentle heat. I tried just 3 fiber CPUs and followed the nitric leach, then decant and washed, then followed by an AR leach. Here are the result.


Nitric leach, guessing removed most of base metals, and the color of this solution either Ni or Co nitrate.



Here is pic of CPUs after completion of nitric leach.



Gold solution after nitric leach completed, the remains after some series of water wash and rinsing, dissolved in hcl and some heat, then filtered



Here is the stannous test for gold solution, shows small amount of gold.



I just added copperas to the above gold solution and waiting to see if it precipitate.

Regards,
Kevin


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## kjavanb123 (Jun 23, 2012)

Ok now the last gold solution you can see in previous post, I added enough copperas to changed solution from light yellow to dark brown, waited for few hrs and solution cleared out still brown, and no precipitant at the bottom? It shows gold in solution before I added copperas. 

Regards
Kevin


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## jimdoc (Jun 23, 2012)

You should be working with more than 3 of those processors so you can actually see the gold.

Jim


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## kjavanb123 (Jun 23, 2012)

jimdoc said:


> You should be working with more than 3 of those processors so you can actually see the gold.
> 
> Jim



Jim,

I haven't started the whole CPU lot yet, this was left over from previous lots, and I was trying to practice recovery method I mentioned, nitric leach then AR leach for gold. Still i should see some sort of brown gold powder at the bottom, shouldn't i? I saw plenty of gold pins ( foils ) what happened to them?!



Regards,
Kevin


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## jimdoc (Jun 23, 2012)

I do not know. I just know that working with very small amounts is tough to do. I think those processors have been determined to have about 25 cents worth of gold in each. So 75 cents of gold would be difficult to see when recovered. Maybe others who have run small sample tests can give you some advice. But I would run enough to actually see results, and with those processors I don't think 3 is enough.
Your stannous results are positive, but week. Stannous is very sensitive, and detects very small amounts of gold. That does not mean it is an easily recoverable amount.

Jim


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