Pin Problems

[Dreamer]

I started off my recovery project with ~ 150 laptops for various vintages and have come to realize that the more you know, the more you realize you don't know. I made it down to the pins and have pruned what was exposed and processed the encased pins in a high speed grinder to liberate them. After gravity separation I have 2.4 KG of finely ground material ~ 40 mesh remaining. Problem is, the metal is balled up amalgamating the gold plating. I've ran several experiential runs with 200gms. Virgin material with cuprous A/P and bubbler took 8 days yielding 0.3 gm. Roasting the material to oxidize the base metals with the same process with being more conservative with the peroxide took 5 days yielding 0.45 gm. Roasting and going straight to HNO3 still left me in stannous hell. Now, I know that I should have been more gentle with the liberation process to preserve the exposed plating. The process would have been much simpler recovering gold foils after dissolving a few u's of base metal and taking it from there, but here I am with some good yielding material. The babysitting and expense of Acid/waste treatment/time is not palatable and looking for a more interesting/profitable way to process this material. Any suggestions would be welcomed.

 

[Yggdrasil]

I started off my recovery project with ~ 150 laptops for various vintages and have come to realize that the more you know, the more you realize you don't know. I made it down to the pins and have pruned what was exposed and processed the encased pins in a high speed grinder to liberate them. After gravity separation I have 2.4 KG of finely ground material ~ 40 mesh remaining. Problem is, the metal is balled up amalgamating the gold plating. I've ran several experiential runs with 200gms. Virgin material with cuprous A/P and bubbler took 8 days yielding 0.3 gm. Roasting the material to oxidize the base metals with the same process with being more conservative with the peroxide took 5 days yielding 0.45 gm. Roasting and going straight to HNO3 still left me in stannous hell. Now, I know that I should have been more gentle with the liberation process to preserve the exposed plating. The process would have been much simpler recovering gold foils after dissolving a few u's of base metal and taking it from there, but here I am with some good yielding material. The babysitting and expense of Acid/waste treatment/time is not palatable and looking for a more interesting/profitable way to process this material. Any suggestions would be welcomed.

Welcome to us.
As you just found out, studies are best done beforehand, but then again lessons may stick better when they hurt/cost a bit
By the way did you some how use Mercury??
Amalgam is an alloy between Mercury and another metal like Silver, Gold, Copper or others.
There is no need for Peroxide in the use of AP, just bubble air through the HCl.

Anyway here are for your studies

We ask our new members to do 3 things.
1. Read C.M. Hokes book on refining jewelers scrap, it gives an easy introduction to the most important chemistry regarding refining.
It is free here on the forum: Screen Readable Copy of Hoke's Book
2. Then read the safety section of the forum: Safety
3. And then read about "Dealing with waste" in the forum: Dealing with Waste

Suggested reading: The Library

Forum rules : https://goldrefiningforum.com/threads/gold-refining-forum-rules.31182/post-327766

 

[Shark]

There is good chance your missing gold is stuck to the blades on your grinding device. Pins do not grind very well and gold sticks where it is smeared.

 

[Dreamer]

Yes, of course. The OG of refining and my starting reference source for processing and refining is Hoke. I would first advise those interested in hydrometallurgy to cover safety and basic chemistry before doing anything. Respectfully, to "Amalgamate" by Oxfords definition is to fold-into or become part of a structure or becoming one. It is has nothing to do with a specific element. My addition of peroxide was to jump start the Cu2+ catalyst since the concentration was low, I understood the risk. Never have I, nor will I, allow a hazardous material enter our environment without comprehensive mitigation at my expense. All base metals are dropped, dried and sent to recyclers and liquids are solar evaporated with the volatiles ran through carbon filters while being released.

Unfortunately, our Father who art in heaven didn't work with computer scrap. I joined this site and became a paying subscriber after some hesitation due to the hostility and rudeness expressed to the general community who may not have the advance science degrees that some us had the opportunity to obtain but since have read some posts/replies from genuine mentors encouraging others, so I felt motivated to contribute.

I was hoping to get interesting ideas about how to process this material. Yes, I could just alloy it add a collector metal and slag off the -ides but I enjoy exploring and learning more about hydrometallurgy. I don't know it all, nor will ever pose to. However, I will always share my experience strength and hope with others as we trudge this road to happy destiny.

 

[Dreamer]

There is good chance your missing gold is stuck to the blades on your grinding device. Pins do not grind very well and gold sticks where it is smeared.

I was liberal with the peroxide on the first run and probably will find it in my cement bath in a year or two! I know it's not necessary but I poured off the solution to check for foils after a couple days and replaced the A/P cupreous solution on the first run. Never thought to check the blades.

 

[Yggdrasil]

Yes, of course. The OG of refining and my starting reference source for processing and refining is Hoke. I would first advise those interested in hydrometallurgy to cover safety and basic chemistry before doing anything. Respectfully, to "Amalgamate" by Oxfords definition is to fold-into or become part of a structure or becoming one. It is has nothing to do with a specific element. My addition of peroxide was to jump start the Cu2+ catalyst since the concentration was low, I understood the risk. Never have I, nor will I, allow a hazardous material enter our environment without comprehensive mitigation at my expense. All base metals are dropped, dried and sent to recyclers and liquids are solar evaporated with the volatiles ran through carbon filters while being released.

Unfortunately, our Father who art in heaven didn't work with computer scrap. I joined this site and became a paying subscriber after some hesitation due to the hostility and rudeness expressed to the general community who may not have the advance science degrees that some us had the opportunity to obtain but since have read some posts/replies from genuine mentors encouraging others, so I felt motivated to contribute.

I was hoping to get interesting ideas about how to process this material. Yes, I could just alloy it add a collector metal and slag off the -ides but I enjoy exploring and learning more about hydrometallurgy. I don't know it all, nor will ever pose to. However, I will always share my experience strength and hope with others as we trudge this road to happy destiny.

Sadly E-waste was not something of Ms Hokes time or she would probably have covered that too
Of course one can go the pyrometallurgical way, but with pins that may be a slightly risky endeavor.
Pins are more than copper and then one will another challenge on the hands.
For Copper alloys no problem just smelt and make anodes for electrolytic refining of Copper.
Your PMs will report in the slimes.
For plated items usually a Sulfuric stripping cell will do it, or for the ones with proper setup Cyanide stripping.

And please drop the religious references here, there are two things not allowed to discuss here, politics and religion.

 

[Shark]

A copper cell is the most overlooked tool a small home refiner can have in his box of tricks. Off course that means some basic knowledge of smelting as well.

Pins, a simple, small and basic sulfuric cell is hard to beat. And can be more forgiving in not knowing the exact make up of the materials. Don’t let my statement fool you as this cell requires full strength sulfuric acid. Sulfuric acid is nothing to get careless with as it is very aggressive and very dangerous. Study and get the right equipment and safety protection.

One of the great things about refining is all the different ways it can be done. We just have to learn when to use which one to be the most efficient to reach our goal (gold).

 

[Dreamer]

Sadly E-waste was not something of Ms Hokes time or she would probably have covered that too
Of course one can go the pyrometallurgical way, but with pins that may be a slightly risky endeavor.
Pins are more than copper and then one will another challenge on the hands.
For Copper alloys no problem just smelt and make anodes for electrolytic refining of Copper.
Your PMs will report in the slimes.
For plated items usually a Sulfuric stripping cell will do it, or for the ones with proper setup Cyanide stripping.

And please drop the religious references here, there are two things not allowed to discuss here, politics and religion.

Didn't mean to offend in any way. I extend my apologies if I harmed anyone's feelings.

 

[orvi]

A copper cell is the most overlooked tool a small home refiner can have in his box of tricks. Off course that means some basic knowledge of smelting as well.

Pins, a simple, small and basic sulfuric cell is hard to beat. And can be more forgiving in not knowing the exact make up of the materials. Don’t let my statement fool you as this cell requires full strength sulfuric acid. Sulfuric acid is nothing to get careless with as it is very aggressive and very dangerous. Study and get the right equipment and safety protection.

One of the great things about refining is all the different ways it can be done. We just have to learn when to use which one to be the most efficient to reach our goal (gold).

Sulfuric stripping is very handy if you have exposed and tin-free material (where gold is dissolved/hidden under tin). New unsoldered pins and stuff, sulfuric stripping cell is the best thing you want to use in terms of produced waste, product and speed. Nothing beats it, in these terms. No exhaust harmful gasses, just oxygen. Only bad thing is concentrated sulfuric.

I can compare it to the AR method, as I practically always process pins by means of AR. And when I uterelly does not need AR to process stuff, I does not use it. I really does not like 5L of waste per kilo of metallic material. Not pleasant, not sustainable in real meaning. This is why I explored I2/KI method earlier, and used it regularly for uniform plated material with nickel underplating. Also wonderful method, if you have right material.
Yeah, you can do gold by quite an array of methods. There is that cheap and efficient cyanide bath, but I never gathered that much courage to practice cyanide bath on regular basis. Just too easy to screw up, and with very fatal consequences. And as my regular batches of high grade stuff were complete mix of everything from pins to transistors, ceramics and stuff, I get used to AR processing, as it was generall, working and efficient. In no means nice and pleasant, but working and useful. I perfected the pathway for like 1 kilo at the time in beakers, sequential processing of bigger quantity in beakers, scale up to the 25L canister, heating stuff in plastic containers by very "obscure" and unusual indirect means and apparatus, 250L drum you name it.

Unfortunately, I probably seen more NOx-es than most of our members would in their entire life. And I am nowhere near retirement. But it all ended now. Today, I probably set the last AR batch of gold plated stuff for processing. Circumstances are what they are... As my partner is gone, I do not have means and possibilities to run this anymore. I hope for nice few grams of gold from that half kilo of pins Sadly, this will not work with sulfuric stripping cell that well. I would need to sort everything.

 

[Dreamer]

A copper cell is the most overlooked tool a small home refiner can have in his box of tricks. Off course that means some basic knowledge of smelting as well.

Pins, a simple, small and basic sulfuric cell is hard to beat. And can be more forgiving in not knowing the exact make up of the materials. Don’t let my statement fool you as this cell requires full strength sulfuric acid. Sulfuric acid is nothing to get careless with as it is very aggressive and very dangerous. Study and get the right equipment and safety protection.

One of the great things about refining is all the different ways it can be done. We just have to learn when to use which one to be the most efficient to reach our goal (gold).

Thanks! Yes, that is a good idea. Absolutely avoid H2SO4 whenever I can. Seems that no matter the extremes of caution, and doing everything in the hood, I damage my work area. Besides acetate salt electrolytes, do you have any other electrolyte suggestions for me to explore? I like fireworks, just not in my lab, lol.

 

[Yggdrasil]

Didn't mean to offend in any way. I extend my apologies if I harmed anyone's feelings.

It was just a heads up
Chemistry and the sciences of nature on the other hand have no feelings, they just do what they do,
so we have to learn how to avoid or coach the processes to our advantage, if possible.

 

[Shark]

As orvi mentioned it is possible to do pins in AR directly but can be pretty hard to get a clean drop and clean the gold. And, at times, even hard to kill off the nitric, as at times it can seem to regenerate itself ( there is an scientific explanation for this but my brain refuses to give that up right now). And as mentioned, the volume of waste can be pretty high. I have used it for smaller batch’s with pretty good results. There is a method I have yet to try using iodine. Similar to using cyanide with less dangers. Orvi would be a good one to ask about iodine.

 

[Alondro]

As orvi mentioned it is possible to do pins in AR directly but can be pretty hard to get a clean drop and clean the gold. And, at times, even hard to kill off the nitric, as at times it can seem to regenerate itself ( there is an scientific explanation for this but my brain refuses to give that up right now). And as mentioned, the volume of waste can be pretty high. I have used it for smaller batch’s with pretty good results. There is a method I have yet to try using iodine. Similar to using cyanide with less dangers. Orvi would be a good one to ask about iodine.

Pins are best done with the HCl-copper chloride route (AP). It's rather slow, but it does a really good job of dissolving the base metals. And it's east to reduce the copper from the waste solution as well after diluting the concentrated waste at a ratio of 1 unit of waste to 3 units of water, then using the iron-copper rods galvanic cell method I've described in another post.

 

[orvi]

As orvi mentioned it is possible to do pins in AR directly but can be pretty hard to get a clean drop and clean the gold. And, at times, even hard to kill off the nitric, as at times it can seem to regenerate itself ( there is an scientific explanation for this but my brain refuses to give that up right now). And as mentioned, the volume of waste can be pretty high. I have used it for smaller batch’s with pretty good results. There is a method I have yet to try using iodine. Similar to using cyanide with less dangers. Orvi would be a good one to ask about iodine.

When I will end all the material I currently have, get my stuff done and get used to new job, I will write everything down. I feel that information and discoveries/inventions that I and my refining partner gathered shouldn´t be lost

In fact, you can do pretty clean gold from pins in straight AR, but I rather prefer first drop on copper. As you completely skip stock pot part, does not need to mind it at all - as you cemented everything on copper already And then you just need to process teeny tiny bit of material/solution, no barrel drums of black liquid
Thing about re-generating "nitric" in AR is real, but it isn´t nitric acid directly. This took me quite a time to realize and "discover", and in fact it very much depends on material you do, and very much also dependent on temperature you hold during the reaction. That is why saturated heavy metal chlorides solutions are such a pain to de-NOx. For real de-nox, it can take hours at 95°C with sulfamic acid... Many times you can get along with only this pretty OK, but good test is SO2 smell. Let me explain:

Usual sequence is to de-NOx hot with sulfamic, observe fizzing to stop, then proceed further. Cool it down and drop with sulfite or preferrably SMB (generating SO2 for dirty gold drop is overkill in my opinion). What happens is - gold obviously drops, but also copper (II) start to be reduced to copper (I) by the excess SO2, and some even complex with it. SO2 is pretty good indicator of the "redox potential" of the mixture. If you can smell SO2 from the liquid (tiniest hint is sufficient), in real terms no gold is in solution as Au(III). If you cannot smell SO2, it is always a bit uncertain. And in diluted Au solutions, full of heavy metals and junk, stannous is useless below 0,2g/L and cannot be relied upon.

Colour of the solution is very good indicator of the redox. If you does not smell SO2 in the morning after dropping the gold in the evening, and solution is more of a green than a brown colour, I would investigate what is going on

Brown colour in Cu solutions appear only when Cu(I) is present. It gradually goes from green, to dirty green to completely brown - at this point CuCl usually starts to crystallize out. If you see deep brown, solution usually cannot have the redox potential for oxidizing dropped gold back into the solution. Also good indicator.

 

[orvi]

Pins are best done with the HCl-copper chloride route (AP). It's rather slow, but it does a really good job of dissolving the base metals. And it's east to reduce the copper from the waste solution as well after diluting the concentrated waste at a ratio of 1 unit of waste to 3 units of water, then using the iron-copper rods galvanic cell method I've described in another post.

Depends on what pins I had pretty bad disadvantage, that my usual day to day material was mix of everything. And time is one of most concerning factors. Time was needed to sort everything, time was needed to run separate batches of sorted stuff, time was needed to thoroughly process the pins in AP.

This was unacceptable for me (us), as we usually processed high grade old pins, >10g/kg Au, and if these were unsoldered and new, you can let them soak in hot AP for a two weeks and they usually lost only like 10% in weight. We did relatively precise measurements, as we were working in bulk and needed to do some "economy maths" You can always cut them, but then gold is smeared everywhere in the machine, another step to be done etc...
AP simply wasn´t working for us. We investigated some shortcuts, determined good rates of dissolution based on temperature, using pure oxygen instead of air (that helped to reduce HCL loss - you can manage closed system with no outgas at all by this - and improved speed quite a bit) etc...

Waste we always done by quicklime hydroxide precipitation. Work and involvement accompanied with copper recovery wasn´t paying enough to be regarded as viable in our situation. Hydroxide cake was then gravity filtered in larger vats (there, we had plenty of time ), sundried and disposed. We investigated also a possibility to cook off the hydrate water and convert the mess to oxides, but I don´t know... It was viable, reduced weight nicely, but you needed to cook it hot. And cooking 200+kg of anything isn´t easy chore

Edit: I would just add that filtering copper hydroxides is much easier than iron hydroxides. That was second thing why we didn´t cemented on iron and proceeded to crash everything out of solution with hydroxide instead.

 

[Alondro]

Depends on what pins I had pretty bad disadvantage, that my usual day to day material was mix of everything. And time is one of most concerning factors. Time was needed to sort everything, time was needed to run separate batches of sorted stuff, time was needed to thoroughly process the pins in AP.

This was unacceptable for me (us), as we usually processed high grade old pins, >10g/kg Au, and if these were unsoldered and new, you can let them soak in hot AP for a two weeks and they usually lost only like 10% in weight. We did relatively precise measurements, as we were working in bulk and needed to do some "economy maths" You can always cut them, but then gold is smeared everywhere in the machine, another step to be done etc...
AP simply wasn´t working for us. We investigated some shortcuts, determined good rates of dissolution based on temperature, using pure oxygen instead of air (that helped to reduce HCL loss - you can manage closed system with no outgas at all by this - and improved speed quite a bit) etc...

Waste we always done by quicklime hydroxide precipitation. Work and involvement accompanied with copper recovery wasn´t paying enough to be regarded as viable in our situation. Hydroxide cake was then gravity filtered in larger vats (there, we had plenty of time ), sundried and disposed. We investigated also a possibility to cook off the hydrate water and convert the mess to oxides, but I don´t know... It was viable, reduced weight nicely, but you needed to cook it hot. And cooking 200+kg of anything isn´t easy chore

I recently made a discovery that the waste acid from dropping gold, using HCl-bleach to dissolve the foils, then metabisulfite to drop the gold, could be used to strip base metals from pins, as well as cement every last bit of gold from the waste acid solution.

This can ONLY be done with a dissolve in HCl-bleach, as using any nitric will result in the dreaded metastannic acid.

It's a good way to reuse waste which would otherwise be thrown out. It'll cut my waste acid volume in half! The copper chloride/copper sulfate in the pin dissolve also is easily processed. The mixture of the two salts appears to cement copper onto iron very swiftly.

It will be interesting to test this waste acid mixture on kovar core pins when I do my CPU stuff.

 

[orvi]

I recently made a discovery that the waste acid from dropping gold, using HCl-bleach to dissolve the foils, then metabisulfite to drop the gold, could be used to strip base metals from pins, as well as cement every last bit of gold from the waste acid solution.

This can ONLY be done with a dissolve in HCl-bleach, as using any nitric will result in the dreaded metastannic acid.

It's a good way to reuse waste which would otherwise be thrown out. It'll cut my waste acid volume in half! The copper chloride/copper sulfate in the pin dissolve also is easily processed. The mixture of the two salts appears to cement copper onto iron very swiftly.

It will be interesting to test this waste acid mixture on kovar core pins when I do my CPU stuff.

Yeah, that works for sure, but I do not know why AR liquors wouldn´t. I never experienced metastannic acid formation in AR in my whole refining career - and it is counter intuitive to expect any, as tin is nicely complexed in high chloride media, stabilized in higher oxidation state and happily dissolved. Nitrate cannot stabilize the tin in solution, so it drops out as metastannic.

I did lot of soldered pins from old connectors, like, heavily soldered, sometimes even 20-30+% of the weight is only the solder (classic 60/40 SnPb). Only thing that precipitate from time to time in my case is CuCl (if you overadd SMB or left it over excess material too long), also PbCl2 and also CaSO4 classic I was curious about precipitates, so I measured them a lot in the past with XRF. Also precipitates from work with silver. And the major analytic marathon was how dissolved ceramic stuff behave in chloride media according to dilution and pH change that was intense...

 

[Dreamer]

Pins are best done with the HCl-copper chloride route (AP). It's rather slow, but it does a really good job of dissolving the base metals. And it's east to reduce the copper from the waste solution as well after diluting the concentrated waste at a ratio of 1 unit of waste to 3 units of water, then using the iron-copper rods galvanic cell method I've described in another post.

Is it worth oxidizing the material beforehand? My second test run yield was better and a little faster but the post digested material was a fine sludge and very diffucult to filter. Also a lot of unidentified white precipitate. I oxidized the starting material until the green flame fades to nearly colorless. Am I overdoing it ?

 

[Yggdrasil]

Is it worth oxidizing the material beforehand? My second test run yield was better and a little faster but the post digested material was a fine sludge and very diffucult to filter. Also a lot of unidentified white precipitate. I oxidized the starting material until the green flame fades to nearly colorless. Am I overdoing it ?

No need to roast it prior to leaching for pins and such, just put them straight into AP.

If one have clean pins without solder one can heat them to red to avoid floaters and such.
Not to oxidize it but to remove organics like oils and fat.

Gold filled and karat Gold should be heated to a low red.

 

[Marcel]

No need to roast it prior to leaching for pins and such, just put them straight into AP.

If one have clean pins without solder one can heat them to red to avoid floaters and such.
Not to oxidize it but to remove organics like oils and fat.

I haven't personally tried it, but I think the idea of oxidizing the pins before any acid process is a good plan. It doesn't require much effort and could potentially expedite the subsequent steps, as oxidized base metals tend to dissolve more easily.