Merged Topics on Ceramic CPU Recovery with Yields

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Thank you,...I guess add more patience and some heat to the mix. Just curious: Do you know off hand how many oz of base metal a quart or gallon of nitric acid can absorb/dissolve before it is saturated? This is useful to know so one can calculate how much material one can safely add to a quart without over saturating it and having to contend with undissolved metal maybe getting into the AR.

I already calculated by weighing them before and after, that six pentium pro chips that are merely smashed with a hammer and placed into AR loose 65 grams of weight. This is without running them through nitric acid first.

Before they were placed in AR they weighed 1 lb 2.5 oz
After the ceramic remains were taken from the AR they weighed 1 lb .40 oz
So basically 2.10 oz or 65 grams of metal dissolved dissolved in AR.

I am wondering if the same ratio applies to Nitric...minus any gold and PG of course since that does not dissolve. Thanks JR
 
JRuth,

This is a very ballpark figure and can vary a little based on the temperature and amount of dilution. I always had good luck assuming that 1 gallon of concentrated nitric will dissolve about 2 pounds of copper or 7 pounds of silver. These figures work out fairly well in practice.
 
All,

This topic got me thinking about what parts of the Pentium Pro actually contain what portion of the gold. In an effort to accurately answer JRuth's question and to put my own mind at ease, I decided to process a single uncrushed PP to determine exactly what I could get from one cpu.

Here are the results of of my test:

1. This is a whole (no lids removed) PP cpu soaking in room temperature 35% H2O2 to attack the tungsten substrate of the heat spreader. To my surprise the peroxide also attacked the solder around the lower lid.

PP_Peroxide_1.jpg


2. After an hour into the reaction I decided to try to speed things up a bit and added 15mL of 10% sulfuric acid and low heat. Here's what I got:

PP_Peroxide.jpg


3. The heat got a little too hot and drove all the peroxide out in one big boil, I didn't lose anything, but the experience was pretty shocking as the beaker went into a runaway reaction of boiling and nearly overflowed. I quickly removed the beaker from the heat and in less than a minute everything calmed down.

4. I placed the beaker back on the heat, but no further reaction occurred. Aside from missing it's lettering and a little pitting on the bottom braze and top lid, the cpu was still intact.

5. I decide to move on to 35% dilute nitric acid and attack the base metals of the lid and pins in an effort to remove the base metals and free the gold plating. Here's the cpu after an hour on low heat in 35% nitric and a gentle scrubbing rinse:

Top:
pp_Top_After_Nitric.jpg


and bottom:
pp_Bottom_After_Nitric.jpg



6. I filtered out the foils from the top, legs and a little debris along with what appeared to be silver chloride (very little). I removed the bottom plate with a MAPP gas torch. I tested the solution for silver (negative) and combined the foils and cpu in a beaker with dilute AR.

7. After an hour on medium heat with AR I obtained a beautiful orange yellow soluiton when the fizzing all stopped. I noticed the cpu still had some residual gold under the cpu dies and around the heat spreader so I removed the die's with a MAPP gas torch to expose the braze as seen here:

Top:
pp_Top_Before_AR.jpg


and Bottom:
pp_Bottom_Before_AR.jpg



Here's the cpu after the second AR treatment and rinsing:

Top:
pp_Top_After_AR.jpg


and Bottom:
pp_bottom_After_AR.jpg


8. Once all the action stopped on the final AR run I filtered the solution and precipitated with SMB. The powder was washed with hot HCl then water and finally melted and weighed. Here's a shot of the 0.310 gram BB of gold from the exterior of a single PP cpu:

BB_310mg.jpg


I still haven't crushed the cpu to determine if the interior holds any gold or not. My guess it may yield another 0.1 gram from the braze under the top lid, but it's only a guess. I'll be very pleased if I see another 0.2 grams from the interior, but I'm not holding my breath. I'll have to wait until I get me hands on a good crusher before I post the remaining yields if there are any.

Please post your comments and suggestions.

Steve
 
With gold I've never used urea to neutralize my AR. Instead I carefully control the amount of nitrate used during the dissolving stage to keep from having to evaporate off the NOx.

With PGMs I perform three evaporation cycles, hydrating with HCl after each to displace the nitrate from the solution.

Steve
 
Lasersteve: Just a thought here, but on what Zamistro said about neutralizing hcl with urea, I tried to do the same with nitric and urea, but absolutely nothing happened What gives ?
 
I have no idea ShadyBear, but I would like to get some sort of answer to my previous post. I have no idea where I saw athe posts on using urea to neutralize nitric or hcl, but some sort of answer would be nice !!!!!!!! Phill
 
EVO-AU said:
I have no idea ShadyBear, but I would like to get some sort of answer to my previous post. I have no idea where I saw athe posts on using urea to neutralize nitric or hcl, but some sort of answer would be nice !!!!!!!! Phill
Click to expand...
I have only used urea to neutralize nitric from an AR solution, it seems like it would take alot to neutralize nitric from nitric.
Where abouts is that in NC how close to the Ashville area gold up there I here
 
Hey Steve, you can use my HCL carbon method. It will travel up inside the chips as it dissolves the pins. As it warms up with more current it will dissolve just about any PM including Platinum.

Just a thought.
DallasGoldBug :idea:
 
lazersteve said:
14. Add Sodium Meta Bisulfite to precipitate gold as brown powder.
Click to expand...

How much Sodium metabisulfite? The other chemicals listed have amounts listed and this one doesn't.
 
Typically you want to use an equal amount of SMB,as the amount of gold you estimate in your solution IE:if you figure theres roughly 3 grams of gold,use 3 grams of SMB,then test your solution after decanting.If using copperas you need to double that figure.
Johnny
 
leavemealone said:
Typically you want to use an equal amount of SMB,as the amount of gold you estimate in your solution IE:if you figure theres roughly 3 grams of gold,use 3 grams of SMB,then test your solution after decanting.If using copperas you need to double that figure.
Johnny
Click to expand...

Cool, thanks Johnny!
 
I found an interesting tibit this weekend. I have a batch of CPU's and Eproms I was running thru som AP. Well I had about 15 PPO's. I was going to run them thru AP to remove the pins and the gold under the silicone chip and then wash them and then deplate the heat sink in a cell. Much to my surprise when I checked this morning the Gold on the heat sink was deplating in a nice sheet. I thunk it might still be attached where the heat sink is attached to the CPU.
 

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