160 pounds of gold pins!

[Oz]

oz,it was a pleasure to see you in the forum again----your friend woul be welcomed here in Saõ Paulo

Even if I am still short of time here I will always make time for you privately. You are good people with intriguing questions. Those questions have led me down paths that I would have not taken otherwise, for that I thank you. We have had fun together, both learning from the other.

 

[HAuCl4]

Will cyanide leach the gold well with so much copper in there?. Wouldn't the copper cement the gold out of solution?. I have read and seen cyanide used for leaching metals out of ores, both in tanks and heaps, but not for gold plated copper. Is there a manual for this process?.

Interesting.

 

[Oz]

Most electronics have a nickle barrier between the gold and copper. If you really want to know cyanide GSP is your man.

 

[Harold_V]

Will cyanide leach the gold well with so much copper in there?. Wouldn't the copper cement the gold out of solution?. I have read and seen cyanide used for leaching metals out of ores, both in tanks and heaps, but not for gold plated copper. Is there a manual for this process?.

Interesting.

I had one negative experience stripping some heavily plated copper base alloys that lacked the nickel barrier that prevents migration of gold in to the base metals. Once the gold plating is perforated, there is aggressive dissolution of the base metal, slowing, if not stopping, further removal of the plating.

As I recall, there are buffered stripping compounds that limit that problem, which tends to be a non-issue if the nickel barrier is in place. Modern plating techniques demand it be there.

Harold

 

[HAuCl4]

Thanks Harold. So cyanide has little effect on nickel, but will readily attack the gold plating?. Will nickel cement the gold out of solution?. I'm sure there must be many nuances to this process. Mmmm.

 

[Lou]

Gold complexes much more easily with cyanide than copper let alone cyanide at low CN- concentrations. The electrochemical series loses way to the thermodynamics of forming a stable complex.

So keep the concentration low. A few organic molecules around to hinder unwanted redox might also be beneficial.

Lou

 

[Harold_V]

Gold complexes much more easily with cyanide than copper let alone cyanide at low CN- concentrations. The electrochemical series loses way to the thermodynamics of forming a stable complex.

So keep the concentration low. A few organic molecules around to hinder unwanted redox might also be beneficial.

Lou

Yep---what Lou said. When using cyanide for heap leaching, or even in vats (agitation), if the percentage of free cyanide is held under .02%, copper is not dissolved, nor does it precipitate any of the gold or silver. That's the beauty of using cyanide for processing ores, assuming they are amenable to cyanide. The only consumption is that which dissolves the values, assuming there are no cyanicides present.

Tons of ore can be leached for a few dollars. Cyanide, when it was readily available, was not expensive.

Harold

 

[goldsilverpro]

Thanks Harold. So cyanide has little effect on nickel, but will readily attack the gold plating?. Will nickel cement the gold out of solution?. I'm sure there must be many nuances to this process. Mmmm.

The cementation reaction requires that the metal (that's doing the cementing) must dissolve. For example, when you use copper to cement silver from a nitrate solution, the copper dissolves at a predictable rate.

In the case of cyanide, the nickel doesn't appreciably dissolve enough to maintain a cementation reaction. However, any exposed copper will dissolve rapidly and will cement the gold.

Simply put, when gold is dissolved, it is done through an oxidation reaction. When it is cemented, it is reduced. You can look at these as opposites. By maintaining the temperature and oxidizer concentration at a high enough level, it is possible to swing the reaction to the oxidation side and prevent the reduction (cementation) of gold onto exposed copper.

When tumbling in a cement mixer for an extended time, the nickel will tend to wear off mechanically and expose the copper. For this reason, enough cyanide and peroxide are used to dissolve the gold quickly - about one or two minutes is normal.

 

[HAuCl4]

Thanks Lou, Harold and GSP. Never thought about it that way. With ores, cyanide basically leaves the crushed rock barren of metals (heap or tank).

So cyanide leach would be the method of choice for this 160 lb lot of plated material?.

 

[Anonymous]

Harold wrote:

When using cyanide for heap leaching, or even in vats (agitation), if the percentage of free cyanide is held under .02%, copper is not dissolved,

Gold Silver Pro wote:

However, any exposed copper will dissolve rapidly and will cement the gold.

Someone care to ellaborate?
And why cause the sollution to be spent,when you can recover with carbon,and incinerate,and save the solution.

 

[goldsilverpro]

Harold wrote:

When using cyanide for heap leaching, or even in vats (agitation), if the percentage of free cyanide is held under .02%, copper is not dissolved,

Gold Silver Pro wote:

However, any exposed copper will dissolve rapidly and will cement the gold.

Someone care to ellaborate?
And why cause the sollution to be spent,when you can recover with carbon,and incinerate,and save the solution.

If my math is right, if the pins are worth $60/pound at a $1200 market, and, if the CN dissolves the gold with 100% efficiency, I figure it will take about 100 gallons of .02% CN solution to do the job. Don't forget that the .02% is a maximum figure - if the CN is made weaker than that (or, if the pins are higher than $60/pound), it will take more solution. Since you will never get 100% efficiency with the CN, it may take twice (or, 10, or, 100 times - I really have no idea) that much solution. In practice, you maybe could use less solution and then occasionally analyze the free CN and add more NaCN to bring it up to snuff - I can see potential problems with this, however. The weak CN solution will dissolve the gold very slowly - maybe, it will take weeks - maybe, it will never completely dissolve all of the gold. Also, you will probably have to tumble the parts. Then, there are potential losses in the incineration.

To strip the 160# with strong CN/H2O2 in a mixer, you might end up with a total of 15-30 gallons of solution, including rinses. It could all be stripped in about 30 minutes. Then, you zinc it and, if you are good at all of this, you will have pure gold bars the next day. The efficiency can be close to 100%, if you do everything right.

No contest, IMHO!!!

 

[samuel-a]

A question for the pro's.

can one melt assorted computer pins and collect the gold with lead/silver and then cupel it?

 

[qst42know]

I'm not a pro but I have tried that very thing.

That would be very inefficient as all the base metals would need to be dissolved into the lead and then oxidized back out either as a slag or absorbed into the cupel.

It is done in a fire assay but difficult in quantity.

 

[CHARLIE GREENLER]

About how much palladium and silver would that pile produce?????I have 50 pound of mixed pins -n- stuff myself.

 

[goldsilverpro]

About how much palladium and silver would that pile produce?????I have 50 pound of mixed pins -n- stuff myself.

Very possibly - none. For what technical reason would these be present? Palladium can be used as a migration barrier in place of nickel, but the only place I've seen that used is on plated jewelry, due to people being allergic to nickel. That whole pile looks gold to me, with the exception of very few little pieces.

 

[HAuCl4]

Harold wrote:

When using cyanide for heap leaching, or even in vats (agitation), if the percentage of free cyanide is held under .02%, copper is not dissolved,

Gold Silver Pro wote:

However, any exposed copper will dissolve rapidly and will cement the gold.

Someone care to ellaborate?
And why cause the sollution to be spent,when you can recover with carbon,and incinerate,and save the solution.

If my math is right, if the pins are worth $60/pound at a $1200 market, and, if the CN dissolves the gold with 100% efficiency, I figure it will take about 100 gallons of .02% CN solution to do the job. Don't forget that the .02% is a maximum figure - if the CN is made weaker than that (or, if the pins are higher than $60/pound), it will take more solution. Since you will never get 100% efficiency with the CN, it may take twice (or, 10, or, 100 times - I really have no idea) that much solution. In practice, you maybe could use less solution and then occasionally analyze the free CN and add more NaCN to bring it up to snuff - I can see potential problems with this, however. The weak CN solution will dissolve the gold very slowly - maybe, it will take weeks - maybe, it will never completely dissolve all of the gold. Also, you will probably have to tumble the parts. Then, there are potential losses in the incineration.

To strip the 160# with strong CN/H2O2 in a mixer, you might end up with a total of 15-30 gallons of solution, including rinses. It could all be stripped in about 30 minutes. Then, you zinc it and, if you are good at all of this, you will have pure gold bars the next day. The efficiency can be close to 100%, if you do everything right.

No contest, IMHO!!!

1 day...Good enough for me!. Thanks a lot GSP.

 

[goldenchild]

I wonder if SS has been taking this all in. SS have you decided on how you'r e going to attack your 3 heaps?

 

[silversaddle1]

Yes, I've been keeping an eye on the thread. Been busy adding to the pile since I posted it. I have added another 15 pounds of pins. I had to start a new bin for them. Looks like 160 pounds of pins will fill a rubbermaid commercial grade tote. These totes contained cow medicine and are heavy duty. So, I'm up to 175 pounds of pins and there is plenty more to pull. Just got a whole box of mid 70's Winchester cable ends to clean. Those are my favorite type of pin to clean as they have real nice looking pins in them. I will try to post a new pic if I can find time.

I think the cyanide route would be the way to go as I have about 100 pounds of fingers to refine as well. It would be nice to just take it all to one place and have it all done at once. I'm in no hurry, it's kinda like my stash. We make our money on all the other stuff we scrap out of these mainframes, the pins/fingers are the cream!

 

[rewalston]

Hey Silversaddle, mind if I ask what your source for pins were? I've been pulling pins from motherboard and IDE cable, etc...I must really be bored

Rusty

Yes, I've been keeping an eye on the thread. Been busy adding to the pile since I posted it. I have added another 15 pounds of pins. I had to start a new bin for them. Looks like 160 pounds of pins will fill a rubbermaid commercial grade tote. These totes contained cow medicine and are heavy duty. So, I'm up to 175 pounds of pins and there is plenty more to pull. Just got a whole box of mid 70's Winchester cable ends to clean. Those are my favorite type of pin to clean as they have real nice looking pins in them. I will try to post a new pic if I can find time.

I think the cyanide route would be the way to go as I have about 100 pounds of fingers to refine as well. It would be nice to just take it all to one place and have it all done at once. I'm in no hurry, it's kinda like my stash. We make our money on all the other stuff we scrap out of these mainframes, the pins/fingers are the cream!

 

[silversaddle1]

Hey Silversaddle, mind if I ask what your source for pins were? I've been pulling pins from motherboard and IDE cable, etc...I must really be bored

Rusty

We do a lot of data center computer recycling. So there are large mainframe type computers, servers, disk arrays, etc. And we get tons of cable. Many times we will find layers upon layers of cables under a raised floor. It looks like they never removed any of the old cable, just layed newer stuff right over the old. The older cable is where we get a lot of the pins from, but also from backplanes, and the computers themselves.