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sail4too2003

Member
Joined
Jan 5, 2010
Messages
18
I have about 25lbs of these pins and have tried aqua regia, straight nitric, and heated sulfuric. I'm not real happy with any of them. I liked the way the nitric worked and got a good showing, but the cost is a bit much. I started with 20 pins at 22.2 grams and got a solid 1.0 grams of gold (I'm guessing it must be around 24k?) I'm pulling most of the wire out of the pins, but some break off inside leaving small trace of copper. Also the parent metal seems to be copper. Can anyone tell me the best way to recover and refine this, or anyone that I can trust to have it done. :roll: This is about half of the total pins shown in pic.
Thanks Terry
 

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sail4too2003 said:
I have about 25lbs of these pins and have tried aqua regia, straight nitric, and heated sulfuric. I'm not real happy with any of them. I liked the way the nitric worked and got a good showing, but the cost is a bit much. I started with 20 pins at 22.2 grams and got a solid 1.0 grams of gold (I'm guessing it must be around 24k?) I'm pulling most of the wire out of the pins, but some break off inside leaving small trace of copper. Also the parent metal seems to be copper. Can anyone tell me the best way to recover and refine this, or anyone that I can trust to have it done. :roll: This is about half of the total pins shown in pic.
Thanks Terry
Click to expand...

Looks like those would be good in a sulfuric cell.
 
sail4too2003 ,

Your pins are millitary type? you have a good yield there, approximately 5% of the mass which would mean about 21 troy ounces of gold.
Which are the price of your seller for 70kg of HNO3 70%, rather than that you need....

teclu
 
Your pins are millitary type? you have a good yield there, approximately 5% of the mass which would mean about 21 troy ounces of gold.
Click to expand...

From my experience, this is one decimal point high. 5% gold is .73 tr.oz. per pound = $800 per pound in gold. For most any pin made in the U.S. since about WWII, that figure is about 10 times too high, with few exceptions. Since 1966, I have processed many 100s of different lots of pins in drum quantities. From all of this, I have only seen one lot that approached your figures. I once ran about 1000# of pins from the 30s or 40s that ran 1 oz/pound in gold. These were also unusual in that there was heavy silver plating underneath the gold.

Concerning "military" scrap. One time, I helped scrap out all the electronics from a large U.S. Naval submarine. Many items were gold plated. However, the thickness of the gold plating was no thicker than the gold plating on reliable industrial components. When I stripped and refined this stuff, I was quite surprised since, at that time, I assumed that the gold plating would be thicker on military stuff. Only a certain amount of gold is needed to protect a certain type of part for a certain amount of time under certain conditions. Anything greater is a waste of gold. The main difference was that there were more types of parts gold plated and more gold coverage on the military electronics. I have seen the same trend on military aircraft electronics.

I'm talking about stuff made in the U.S. I've seen figures on this forum that would indicate that Russian stuff was plated thicker. I also remember someone talking about heavily gold plated Russian pins that had silver underneath the gold. When silver was used under the gold, the gold had to be very thick in order to prevent or slow down the migration of silver up through the gold. If the silver migrates completely to the surface of the gold, it tarnishes. Modern electronics don't use silver under the gold. They use nickel. This prevents any migration and greatly reduces the gold thickness requirements.

For about 5 years, in the late 60s - early 70s, I was the senior chemist for the largest supplier of gold plating systems in the world (at that time). We supplied plating systems to many large companies that plated military electronics. I made 100s of trips to those various facilities to help setup or troubleshoot their systems. Even at that early date, nickel was always used under the gold and the gold plating was about the same thickness as that used today for any reliable military or industrial components.

As Barren Realms suggested, I would run these in the sulfuric cell.

Chris
 
GSP,
Hello sir!

I just calculated after sail4too2003's statements:

...I started with 20 pins at 22.2 grams and got a solid 1.0 grams of gold ...

Yes sir you are right, I talked about the silver layer under gold layer at the russian pins case. I can prove that the yield for 1 kg russian military pins is 30-100 grams of gold and 40-150 grams of silver,...depends on the type of connectors and of course very very important the gender female/male,
....of course all this was possible only with all precious advices that I received from you and from those members of this forum.

teclu
 
teclu said:
I just calculated after sail4too2003's statements:

...I started with 20 pins at 22.2 grams and got a solid 1.0 grams of gold ...
Click to expand...
teclu,
Sorry I doubted you. I guess I didn't read sail4too2003's post in detail. And, assuming the yield is right, I might agree with you as to using nitric acid. It would only take about 12 gallons of nitric to process the 25 pounds and get $18,800 worth of gold. At that gold thickness (about 300 millionths of an inch, or more), however, I would think it would take forever for the nitric to penetrate through the gold to get after the copper. Gold plating is porous until the thickness is about 100 millionths - at that point, it's pretty well sealed up, unless the gold plating is extremely stressed. That's how the nitric penetrates - through the pores. It could be like running gold filled in nitric, or worse. At that yield, however, I would probably use aqua regia, with a minimum amount of nitric, and then probably use SO2 to drop the gold out.

sail4too2003,
Please forgive me but, after reading your post more carefully, I have doubts about the yield you claim. If the yield is true, you have found the one out of 1000, or more, batches of pins that run that high, at least in the U.S. Did you melt the one gram of gold? If so, what did the bead look like? If you are basing it on powder and/or foil weight, the yield is definitely in doubt.

I would suggest you take that one gram of "gold", process it through aqua regia, drop the gold out, clean it, melt it, and see what weight you end up with. Better still, put 1/2 pound of pins through the nitric and then dissolve the foils in aqua regia and go through the rest of the procedure.
 
When I ran the 22.2 grams I broke the end off and these were the male pins, so I kept them in until I had no reaction, and they then sat another hour. I watched some vids on cells and I like the process also. but I,m no expert. Thanks for all the feed back. Also these came from a manufactering plant, lots of robotics and large machines running 24/7 Terry
 
sail4too2003 said:
When I ran the 22.2 grams I broke the end off and these were the male pins, so I kept them in until I had no reaction, and they then sat another hour. I watched some vids on cells and I like the process also. but I,m no expert. Thanks for all the feed back. Also these came from a manufactering plant, lots of robotics and large machines running 24/7 Terry
Click to expand...

Were these rejects from the manufacurer?
 
I agree with GSP, the yield is very high for American made pins.

When i read the post I immediately suspected the yield may be contaminated with copper, weighed wet, or some other anomaly had occurred.

GSP has made some excellent suggestions for verifying your numbers.

If your numbers are right, you've hit the jack pot.

Steve
 
The gold plating on pins like these is quite porous. I used to order loads of gold-plated electrical components. The thickness of the gold really doesn't help the conductivity in most applications after you go beyond 20 microinches.
It is interesting that some people here have seen silver underplate for gold. In my experience, silver under gold is bad because the silver will tarnish (combine with sulfur) and the resulting AgS expands in volume. It mushrooms up through the pores in the gold and makes the gold look like it is tarnishing. Usually you need to have a thin layer of something between the silver and the gold to prevent the mushrooming.
 
Barren Realms said:
Why not the cell route GSP? Wouldn't that be faster and less base metals to worry about getting in your solution?
Click to expand...
If that yield is right - 18.8 tr.oz.- you should have a big cell. Otherwise, you would spend all your time harvesting gold. The sulfuric cell will only take so much gold before it starts to short out. At that point, you have to harvest the gold. I never kept track, but I would guess that when you get about 1 to 1.5 oz of gold per gallon of sulfuric, you'll have to harvest. Each time you do this, it requires removing the electrodes, settling at least overnight, carefully siphoning or decanting, adding more sulfuric, replacing the electrodes, and starting over again. Therefore, if I were going after 18.8 oz of gold, I would want to start with at least a 3 gallon cell. With only a 1/2 gallon cell, it might take weeks to run all that material through it. Also, I wouldn't attempt this without some sort of tumbler. Without a tumbler, you might add another week or two, in order to get all the gold dissolved. Don't get me wrong. I love the sulfuric cell but I understand it's limits.

I never really worried about working an aqua regia solution with tons of base metals dissolved in it. The gold drops efficiently whether there is a lot of base metal contamination, or not. So what if you have to run the gold a second time. I could re-run 19 oz of gold powder in 1/2 day, maybe less. In my experience, the entire secret of aqua regia is to keep from using any excess nitric acid when dissolving the parts (or powder). With 3 or 4 buckets, I could run that 25# of pins in aqua regia and re-run the powder easily in 2 days. Here again, I'm talking about a total of 18.8 oz of gold in the 25#.

If there was only 1.88 oz in the 25# of pins, which to me is more likely, I would not use aqua regia. I also would not use nitric. I would use cyanide/H2O2. If I didn't have cyanide, I would use the sulfuric cell and rig up some sort of tumbler. If I were dead set on doing this, but didn't want to set up a cell to run that small amount of gold, I might even consider AP.
 
chemist said:
The gold plating on pins like these is quite porous. I used to order loads of gold-plated electrical components. The thickness of the gold really doesn't help the conductivity in most applications after you go beyond 20 microinches.
It is interesting that some people here have seen silver underplate for gold. In my experience, silver under gold is bad because the silver will tarnish (combine with sulfur) and the resulting AgS expands in volume. It mushrooms up through the pores in the gold and makes the gold look like it is tarnishing. Usually you need to have a thin layer of something between the silver and the gold to prevent the mushrooming.
Click to expand...

chemist hello,


Probably is Ni between the Ag and Au but for me is not so important, it dissolves with base metals...
It is true, the Ag is "very bad" for me also because my gold foils must be rinsed often and very well to prevent the formation of silver chloride in AR.

teclu
 
goldsilverpro said:
If that yield is right - 18.8 tr.oz.- you should have a big cell. Otherwise, you would spend all your time harvesting gold. The sulfuric cell will only take so much gold before it starts to short out. At that point, you have to harvest the gold. I never kept track, but I would guess that when you get about 1 to 1.5 oz of gold per gallon of sulfuric, you'll have to harvest. Each time you do this, it requires removing the electrodes, settling at least overnight, carefully siphoning or decanting, adding more sulfuric, replacing the electrodes, and starting over again. Therefore, if I were going after 18.8 oz of gold, I would want to start with at least a 3 gallon cell. With only a 1/2 gallon cell, it might take weeks to run all that material through it. Also, I wouldn't attempt this without some sort of tumbler. Without a tumbler, you might add another week or two, in order to get all the gold dissolved. Don't get me wrong. I love the sulfuric cell but I understand it's limits.

I never really worried about working an aqua regia solution with tons of base metals dissolved in it. The gold drops efficiently whether there is a lot of base metal contamination, or not. So what if you have to run the gold a second time. I could re-run 19 oz of gold powder in 1/2 day, maybe less. The entire secret of aqua regia is to keep from using any excess nitric acid when dissolving the parts (or powder). With 3 or 4 buckets, I could run that 25# of pins in aqua regia and re-run the powder easily in 2 days. Here again, I'm talking about a total of 18.8 oz of gold in the 25#.

If there was only 1.88 oz in the 25# of pins, which to me is more likely, I would not use aqua regia. I also would not use nitric. I would use cyanide/H2O2. If I didn't have cyanide, I would use the sulfuric cell and rig up some sort of tumbler. If I were dead set on doing this, but didn't want to set up a cell to run that small amount of gold, I might even consider AP.
Click to expand...

Ok so because of his yield data (if it is correct and most here think it is not correct) you would go with the AR and fight the base metals in solution. And I know that is not a good way of putting it because you are not having to fight with them. And then clean it up on the 2nd run of the gold. And that brings up another item. If his figures are correct and there is silver under the gold because of the heavy plating as has been posted you would also have the silver out of it to recover.

However if his figures are not correct and the returns are .25-3 grams per pound he would be better off going with a cell. I agree that a cell like Steve shows in his video would be too small for this volume of material.

Now if a continuious cell is made to process this material for instance. Take a piece of 6" SCH 80 PVC pipe 18" in length in a vertical/ up&down position (( hold's 1.35 gal of fluid/ft roughly 21.6 cups (http://www.deh.enr.state.nc.us/osww_new/new1/images/PVC_Size_Volume.PDF)). Reduce the bottom opening to 2" (hold's .153 gal/ft roughly 2.448 cups). Install a 2" SCH80 threaded ball valve below the reducer. The threaded 2"x18" pipe under the valve can then be unscrewed and the settled gold recovered. The 2" pipe will need a small valve to remove some of the acid before the pipe is unscrewed to reduce spills say 3/8" pipe. Now if the 6" pipe is filled with 1.35 gal of sulfuric aprox 12", a 3"x6" pipe can be lowered inside of your 6" pipe holding the pins. Your anode and cathode set up and you are running. You could use some 1/2" copper tubbing inside of your 3" pipe for your anode and hang some lead on the inside of the 6" for your cathode. I suggest SCH80 pipe because it can be threaded.

How many ounces of cell processed gold will it take to fill 1 cup?

If the 2" pipe is emptied of it's contents and new fluid added to the existing in the 6" pipe back to the original level would this be adequate or would your solution still show a short and need more new fluid than the 2.448 cups that was in the 2" pipe.

This cell would be roughly 28-32 cups with the valve and reducers. Roughly 10 times the size of Steves 3 cup cell. Would this be overkill or underkill for the 25 lbs of pins he is talking about doing.

I know I should show a little more detail than this but it is late.

Getting ready for the first snow of the year here. Yea and I know some of you are laughing real hard at me now. Hey snow is a festival around here for us.

Ok I will put my dunce hat back on now.
 
Barren Realms,

I discussed a similar sludge removal arrangement on this thread.
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=37&t=3236

Today, for gold plate over silver plate, I would probably use the sulfuric cell. It will strip both.

When I stripped the heavy gold/silver pins that I mentioned in my post, I tumbled them in a cyanide/m-NBSS/H2O2 mixture at about 140F. The m-NBSS is a fairly inexpensive oxidizer that also inhibits attack on the copper.

Chris
 

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