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Here is the result of a process GSP helped me with.It took about 10 minutes to set up,about 2 hours to run the material,about 30 minutes to precipitate,and about an hour to redissolve and wash.Total time was 1 afternoon,not bad for an ounce and a half.
Thank you Chris,I appreciate you helping me on this one.
 

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A little over a pound of plates from mil-spec cpus,and a little bit of some other mil spec stuff I've been dying to play with.
 
That is very very nice. Only took a couple of hours. Glad it worked so well for you!
 
glondor said:
Glad it worked so well for you!
Click to expand...
Thanks Mike,so am I.
I knew I still had one 5-gallon bucket of solution,that I still had to drop.......however I must have put another bucket behind that one and didn't see it.Guess what I am doing today? :mrgreen: Of course the purpose of this thread was to pay homage to Chris.He took a lot of time to work with me on this.
 
mic said:
A little over a pound of plates from mil-spec cpus,and a little bit of some other mil spec stuff I've been dying to play with.
Click to expand...

Those are some very high yield cpu's.

great work mic, looks very pure
 
samuel-a said:
Those are some very high yield cpu's.
Click to expand...
Yes I am fortunate enough to be given tons of equipment,that most people will never have the pleasure of seeing.I took some pictures a long time ago of some of the equipment,because a lot of it was proprietary to a certain job.I just recieved 2 133mhz P-Pros and a "Prototype" National cpu.I have seen many "Engineering Sample" chips coming from NASA or one of it's contractors.I save some stuff that is rare,and sell some of it.
But getting back to the yields.....yes,most of what I get has a much higher yield than factory standard material.
I am working on trying to find a company,to process the boards that I have accumulated from nasa over the years.I wish we had a place close where I could watch the procedures,but alas there isn't.
samuel-a said:
great work mic, looks very pure
Click to expand...
Thanks sam,all I do is redissolve about 3 times,then a water boil.It is more time consuming than the "3-3-3" washes,but it makes for some aweful pretty gold.
 
mic said:
but it makes for some aweful pretty gold.
Click to expand...

Hell yea.

mic said:
Thanks sam,all I do is redissolve about 3 times,then a water boil.It is more time consuming than the "3-3-3" washes
Click to expand...

When you get the chance (if you didn't already), do a second/third drop with oxalic acid, you'll be amazed.
It does takes more preparations, but you are a patient man, so i see...

Anyways, photos of your feedstock will be very welcomed if possible to disclose them.
 
samuel-a said:
Anyways, photos of your feedstock will be very welcomed if possible to disclose them.
Click to expand...
Here is a pic of the plates for now,I post some more pics later.We just got home and I have to run out to the shop and start filtering.
 

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Back in the day I used to process that type of scrap by the drum full in dissolves as big as 400 gallons. We used a simple technique to save on labor, filtering, and chemicals.

The scrap was first digested in aqua regia 4:1 and we fed in material until the acid was spent. What was happening was the base metals (a lot of copper) essentially forced all of the dissolved precious metals out of solution. We would feed scrap until the stannous went from showing gold to not showing gold and then stop.

It now settled overnight.

In the morning test with stannous to make sure there was no gold in solution. Then we would siphon off the acid which was waste treated, and filter the solids. This was all sorts of crap, ceramics, glass plastic and of course gold, platinum, and palladium. All of this was put back up in aqua regia.

This time most of the base metals were gone and the acid stayed a nice red color but we only needed about 10% of the acid we needed originally. This reaction we were always careful to only add enough nitric to do the job. The savings of not having to drop or filter the large digestion was a big deal, both in time and chemicals.

The solution from the second digestion was filtered and the PM's were dropped normally. The solids that remained on the filter did have some values, primarily silver, so it was dried crushed and sifted to make a low grade sweep. Silver was 3 bucks an ounce then and it was viewed as more of a nuisance than it was worth.

On that second drop the gold was always saleable at .999+

That was when the circuits really had some values in them. In my opinion, they should shoot the guy who invented flash plating! (unless of course if it was GSP!)
 
4metals said:
Back in the day I used to process that type of scrap by the drum full in dissolves as big as 400 gallons. We used a simple technique to save on labor, filtering, and chemicals.

The scrap was first digested in aqua regia 4:1 and we fed in material until the acid was spent. What was happening was the base metals (a lot of copper) essentially forced all of the dissolved precious metals out of solution. We would feed scrap until the stannous went from showing gold to not showing gold and then stop.

It now settled overnight.

In the morning test with stannous to make sure there was no gold in solution. Then we would siphon off the acid which was waste treated, and filter the solids. This was all sorts of crap, ceramics, glass plastic and of course gold, platinum, and palladium. All of this was put back up in aqua regia.
Click to expand...
While I have never processed 400 gallons at one time.....ever......this procedure is almost identical to the process I use now.
Steve taught me about adding nitric to AR in small stages until you saturate the AR and force the gold back out.It's a little different though.
In my process If your solution is saturated but you have a decent amount of base metals,you simply add more Hcl for absorbtion,and back to adding nitric in small amounts.Once most of the base metals are gone,just decant the saturated acid and add fresh AR,and proceed the same way you stated.
 
4metals said:
Back in the day I used to process that type of scrap by the drum full in dissolves as big as 400 gallons. We used a simple technique to save on labor, filtering, and chemicals.

The scrap was first digested in aqua regia 4:1 and we fed in material until the acid was spent. What was happening was the base metals (a lot of copper) essentially forced all of the dissolved precious metals out of solution. We would feed scrap until the stannous went from showing gold to not showing gold and then stop.

It now settled overnight.

In the morning test with stannous to make sure there was no gold in solution. Then we would siphon off the acid which was waste treated, and filter the solids. This was all sorts of crap, ceramics, glass plastic and of course gold, platinum, and palladium. All of this was put back up in aqua regia.

This time most of the base metals were gone and the acid stayed a nice red color but we only needed about 10% of the acid we needed originally. This reaction we were always careful to only add enough nitric to do the job. The savings of not having to drop or filter the large digestion was a big deal, both in time and chemicals.

The solution from the second digestion was filtered and the PM's were dropped normally. The solids that remained on the filter did have some values, primarily silver, so it was dried crushed and sifted to make a low grade sweep. Silver was 3 bucks an ounce then and it was viewed as more of a nuisance than it was worth.

On that second drop the gold was always saleable at .999+

That was when the circuits really had some values in them. In my opinion, they should shoot the guy who invented flash plating! (unless of course if it was GSP!)
Click to expand...

This is a great method and you detailed it very well! I learned it in about 1980 from a guy that was dissolving gold bearing stainless in a 50 gal heated Pfaudler. Lots of waste base metal solution but the beauty is that all the gold ends up being in a separate concentrated solution containing very little base metals (there will always necessarily be some). We used an AA to test the main solution for gold. When it showed, we added a little more stainless until the gold test was negative. As 4metals said, the residues (containing all the gold, etc.) were finally collected and dissolved in AR containing a bare minimum amount of nitric. The whole thing was done in one long day. I'm thinking that Harold used this method also. I know we've discussed it.

For the lids with Au/Sn braze, similar to those in the photo, I ran them in a modified sulfuric stripper using a plating barrel. Took about 20-30 minutes to strip. I remember we once ran a lot of 1100# of new lids (much smaller and thinner than those in the photo), with a Au/Sn preform on them, that ran an ounce of gold per pound.

Flash plating, spot plating, zone plating, strip plating, selective plating, etc. From a scrap viewpoint, I hate them all also, but they sure saved the manufacturers a lot of money after they paid for the high dollar plating equipment. I wish I had invented it. If I remember right, this equipment started to appear on the market in the mid 70s, when the gold price really started to climb. Why put thick gold (or any gold at all) on areas that don't really need it? It was a very logical cost reduction thing to do.
 
goldsilverpro said:
I'm thinking that Harold used this method also. I know we've discussed it.
Click to expand...
Yes, I did, but only for a specific reason. I used it when I'd receive a large amount of dental material (primarily caps), laced with valueless pieces. It was faster and easier to dissolve everything with AR, then allow the values to cement on the remaining base metals. That consumed more of the base metals in the process. The hard part is to know when to stop, while there's still enough base metal to cement the values, but not so much as to result in a very dirty final solution. As Chris alluded, there will always be some included, so the goal is to minimize the amount.

This process is the reason newbies get in trouble. They don't understand the ramifications of dissolving values with base metals present, so they either lose values to the remaining base metals (Hey! where the hell did my gold go?), or they carry the operation too far and dissolve everything, yielding a terribly dirty solution.

By the way----I came up with the process through reasoning. I wasn't aware others used it, although I'm certainly not surprised. It's a good tool when used properly.

Harold
 
Thank you Harold for pointing out that this is not a technique for newbies, it is only a technique that should be tried when one is totally comfortable with testing with stannous and familiar with the look of solutions that are saturated with metals. That comes from hands on experience, not reading on the internet or in a book.

It can totally throw off a novice who knows a solution was reading positive for gold only for it to "disappear". And now that I think about it, quite a few questions have been posted by newbies who thought they had it, and lost it.
 
samuel-a said:
mic said:
Thanks sam,all I do is redissolve about 3 times,then a water boil.It is more time consuming than the "3-3-3" washes
Click to expand...

When you get the chance (if you didn't already), do a second/third drop with oxalic acid, you'll be amazed.
Click to expand...

Hi mic
Just wanted to follow up on the oxalic acid, here is a picture of a sample after dropping with oxalic acid.
This gold was refined first with AR and reduced with SMB, then again AR and oxalic acid. No acid washes in between.
I think the shape and color speak for themselves...
 
Question. Dropping gold with Oxalic acid. This is done at close to boiling? is that correct? Is It 2 x Oxalic acid to gold? I have some but have not tried it yet.
 
Maybe it's just me, maybe it's the season. I am in the mid-west and it's Morel mushroom season here and that sure resembles a Morel floating in that jar.... :shock:
 
step wise for Oxalic acid:
  • Oxalic acid (dehydrate) used at 1:1 weight ratio for the expected gold from solution.
    (I use a slight excess Oxalic)
  • Dissolve in D. water, water level should not exceed one 1/3 height of the beaker.
  • Raise pH with ammonia solution/NaOH to about 6.
  • Heat both gold solution and Oxalic solution to near boil.
  • SLOWLY add gold solution to oxalic solution, by slow i mean a few drop at a time with a glass pipette. The more concentrated your gold solution is the more vigorous the reaction is. (cover the oxalic beaker almost completely with a watch glass while adding the gold to contain splattering)
  • When done adding the gold, give it a good stir with glass rod and keep the reaction beaker 10 more minutes on the hotplate at near boil.
  • Remove beaker from heat and allow it to settle over night.
  • the following day, Solution should be clear and colorless (assuming it is a second refining), test with SnCl. If negative, filter the solution and discard, if slightly positive, decant the solution to another beaker, add some SMB and let is sit for few more hours or over night.
  • Wash gold powder: 3x water, 3x HCL, 3x D. water.
  • Dry gold powder
  • Melt
 

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