Have I struck gold?

[bemate]

5g in 600g = 120:1 = 0.8%, and sounds conceivable for plated pins.
I expect that one's processing method would affect the final yield as much as would the originating material. If you would be so kind, share with us your own final result.

Will do, but I'm just starting out at the middle of the learning curve, so I estimate it will be a good while before I do any actual wet work. The tests I have performed so far are just qualitative tests to get a feel for the material. Unfortunately I have neither time nor facilities to process any kind of amounts, yet...

I will, however, keep that particular batch of pins separate from my other materials as I slowly build my stockpile. And let's not forget I still have no idea how to separate the pins from the plastic in a reasonable way, I'd rather not have to burn that much plastic...

 

[Barren Realms 007]

Well to make a long post short if they were mine I would just remove the wires from the pins and process them still in the connectors in poor mans AR and drop out the gold. But that is just me. You are not at the point in your processing experience that you should feel comfortable doing them this way and I'm not advising you to do them this way.

I did mention to leave the connectors in the freezer overnight. Leaving them in the freezer for just a couple of hours is not a long enough time for them to become cold enough to shatter when hit with the hammer.

Your success in this field of endevour with depend on how well you follow instructions given to you.

 

[Topher_osAUrus]

To add to Barren's post.

Patience is what makes or breaks you (and the cases in this, er, case..)

I do believe that i got impatient and threw a couple into AR, which went horribly, as the plastic turned to mush and covered everything. They went fine in AP, it was just tedious to spray out every flake of gold from inside the connectors.

But, those are green, mine were black. Color might not be the only different (composition of the plastic, may be as well)

But, you should let them freeze for a day or two, maybe even throw them in the freezer wet, so the water expands inside the plastic. Then beat them like nobody's business.... Or find a good old blender that can do the beating for you.

 

[bemate]

But, you should let them freeze for a day or two, maybe even throw them in the freezer wet, so the water expands inside the plastic. Then beat them like nobody's business.... Or find a good old blender that can do the beating for you.

Now that might just do the trick, the water should permeate the connectors and help with the breaking. That's exactly the kind of thinking I like.

As for rushing the freezing: (and not to be defensive) It was a lab freezer at -80 degrees celcius, not a standard -20, and it was only 2 connectors so they were completely frozen through. Maybe not all the way to -80, but well below -20. Though I will concede that time also plays a role.

I have also looked at what makes plastic brittle under normal circumstances, and apart from age, it seems heat and UV radiation might be alternatives.

I'll try baking one at a low heat for a while and put one under a UV-lamp in addition to freezing with water. If it works out, I'll probably make a separate post in the techniques-forum about it.

Again, thanks for the input guys, I really appreciate it.

B

 

[anachronism]

I've had those green things before. Now assuming they are the same, and we can't be sure of that but a week in HCl dissolved the plastic on mine.

 

[bemate]

As it turns out, the answer was simple: Acetone. I left a sample over night in Acetone, and lo and behold: the plastic crumbled like cheese curds. I am now in the process of extracting the pins, and for most of the connectors it's more or less a question of pulling them apart by hand.






So, that cleared up that well enough, next step now is to burn off the rest of the plastic from the small wires and try to get rid of the solder at the same time. I was thinking I'd roast them with a simple propane torch designed to burn weeds. If I do this on a stainless steel mesh the solde should mostly just drop off provided I get it hot enough.

 

[upcyclist]

As an aside, don't forget to first run your pins through HCl to dissolve any tin in the solder. You'll read lots here about the metastannic acid mess you'll create if you go straight to nitric or AR

Speaking of things you'll read about here, also roast your solids after the HCl soak to remove any chlorides, lest a follow-on nitric soak becomes AR before you're ready for it. Always roast between acids until you're ready for AR.

 

[bemate]

As an aside, don't forget to first run your pins through HCl to dissolve any tin in the solder. You'll read lots here about the metastannic acid mess you'll create if you go straight to nitric or AR

Speaking of things you'll read about here, also roast your solids after the HCl soak to remove any chlorides, lest a follow-on nitric soak becomes AR before you're ready for it. Always roast between acids until you're ready for AR.

Good points, will keep it in mind.
Actually, since the pins appear to be pure copper without any nickel as far as I can see, I was thinking about doing a slow AP leach which would give me a fairly pure copper chloride solution to use on future AP leaches. I want to make sure I remove as much other metal as possible beforehand.
My internal struggle now is whether to invest some time to sort my pins to educate myself with them, or keep them collected to calculate yield on the batch as a whole...

Mind you, for now I'm just reading, thinking and doing micro-scale reactions in test tubes at the lab where I work to familiarize myself with the sources and chemicals.

I'm looking at the possibility of making a closed AP-setup with fumes directed through a scrubber. That way I can set it up outside my garage without being an eyesore.
But it's still a theoretical project so far.

 

[upcyclist]

As an aside, don't forget to first run your pins through HCl to dissolve any tin in the solder. You'll read lots here about the metastannic acid mess you'll create if you go straight to nitric or AR

Actually, since the pins appear to be pure copper without any nickel as far as I can see, I was thinking about doing a slow AP leach which would give me a fairly pure copper chloride solution to use on future AP leaches. I want to make sure I remove as much other metal as possible beforehand.
My internal struggle now is whether to invest some time to sort my pins to educate myself with them, or keep them collected to calculate yield on the batch as a whole...

AP, since it's an acidic chloride solution, will do the trick too. Realize that afterwards, then, your solution won't actually be "fairly pure copper chloride"--it'll be a mix of copper & tin chlorides (as well as nickel, lead, etc.--whatever it ate), so it might lose power after a while until you refresh it with HCl.

Lots of ways to skin a cat, you find the one that works best for you.

 

[jason_recliner]

My internal struggle now is whether to invest some time to sort my pins to educate myself with them, or keep them collected to calculate yield on the batch as a whole...

On the subject of investing time, one of the most significant characteristics of plated pins is their notoriously low yield. The precious metal value is so low that they are rarely worth any great deal of human time. For this reason it is not uncommon practice to toss them in a bucket and forget about them for a few months. This way one wastes the least oxidiser, electricity and human interaction.

If I were to do pins or equivalent these days, I would also dilute the HCl concentration from ~30% to just under 20%; this is HCl's azeotrope. My remedial-level chemistry comprehension is that any higher concentration than this will only evaporate off to that value anyway, but I welcome any correction on this point.

 

[upcyclist]

Doh. I thought the azeotrope of HCl was about 35%. Now I know better, and wait to see what people say about your idea.

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[bemate]

I will go out on a limb and assume that some of you find this thread somewhat interesting.

Having soaked the plastic parts and extracted the pins over a few days, I took the time to sort them as well. Some would probably argue that is wasted time, but then again, you don't calculate the price per kg for fish you catch when you go fishing for recreation (I hope...)

I sorted the pins into three piles; clean ones, soldered ones and the vast majority that is with wires wound around, though not soldered.


I also weighed several of the clean ones and found the average weight to be 324mg, making it 633g total weight without solder and wires.

And so comes a small question: if I take the soldered ones and soak in HCL, the solder should dissolve nicely. That would give me a tin/lead-solution, possibly with some other contaminations. If I then treat this solution with a bit of sulphuric acid, the lead should drop out as sulphate. Would the remaining (mostly)tin solution then be usable as a stannous chloride test solution?

 

[upcyclist]

I would use known, clean ingredients for a test solution like that. I would not go with 'I think it's mostly tin chloride'. Get yourself some lead free sinkers or something like that, and use those.

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[bemate]

I would use known, clean ingredients for a test solution like that. I would not go with 'I think it's mostly tin chloride'. Get yourself some lead free sinkers or something like that, and use those.

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I had an inkling that would be the first answer... :wink: I'll look for some of those singers, or I might just buy some tin bars online. For some reason, pure tin is very hard to find in less than several kilogram batches here... It's almost as if no one casts their own tin soldiers anymore. But that's a minor inconvenience, I don't plan on having any solutions I need to test for quite some time anyway.

 

[g_axelsson]

Check in a second hand store for banged up pewter objects and buy a cheap one, it will last a lifetime.

Göran

 

[anachronism]

One reel of tin solder will also last a lifetime. It's the blue stuff in the UK. Readily available online or in your local DIY store.

 

[bemate]

One reel of tin solder will also last a lifetime. It's the blue stuff in the UK. Readily available online or in your local DIY store.

The closest I've found so far is 99,3% Tin and 0,7% Copper. Will that do? I assume I want the clean type without solder incorporated in the thread?

 

[jason_recliner]

Yes, that's spot on and is what I use.
A little (or even much) copper or lead (i.e., Göran's pewter) will not throw off your tests at all.

 

[anachronism]

As Jason said- it's perfect.

It's also cheap, effective and you'll never have problems. Keep a small jar (literally a few ml) of weak gold chloride to one side when you've made some. You can regularly put a drop of it with a drop of your stannous to provide a base line test to make sure your stannous is working.

 

[upcyclist]

Exactly--I hope you didn't think I meant your source material had to be 100% tin, just mostly tin and a known saturated solution. You'll see when you search on how to make your own solution, but basically you use full-strength muriatic and keep an excess of tin in the solution (that not only keeps it saturated, but gives you a visual indicator of that as well). A full-strength stannous chloride solution is very good at detecting very small amounts of gold in solution.

My 'standard' gold chloride solution is a lot stronger than it needs to be, so I occasionally top it off with muriatic to thin it out bit by bit. I should just throw half the bottle (a wee 0.5 fluid ounce dropper) in my next refine and top it off again. I don't use much of it anyway--you really only need to confirm your stannous when you get a negative result and you suspect otherwise.