# Darn PINS



## GotTheBug (Oct 20, 2012)

I've been shaving the pin carrying plastic assemblies off the boards, like most of us (I would guess) here. First test batch, I used way too much oxidizer (bleach) with the HCl and ended up with a molten plastic mess, hence the current profile pic. Last batch I tested, used 750mL of HCl, 750mL water, and 100 mL of 9% peroxide (27% cut with water) to try and remove the gold plate from the pins while leaving the plastic alone. I am STILL ending up with nasty, sticky foam and some apparently molten plastic, though at least I can see a couple pieces of gold in the bottom of my bucket. Am I still using too much peroxide in the beginning? Ideas? 

Thank You in advance for helpin a noob....

Paul.

PS. The various assemblies are ide, ram, usb plugins off the board, as well as some cable plug ends that have that precious color.


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## goldenchild (Oct 20, 2012)

Remove the pins from plastic and use an H2SO4 cell.


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## ericrm (Oct 20, 2012)

your problem, it is the hcl disolving plastic ,not the other chemical 
yoiu should look at that post it will be helpfull: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=46&t=13356&p=134154#p134154


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## GotTheBug (Oct 20, 2012)

ericrm said:


> your problem, it is the hcl disolving plastic ,not the other chemical
> yoiu should look at that post it will be helpfull: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=46&t=13356&p=134154#p134154




Thank You Eric!
So I have some separating to do now, and that thread was the lightbulb I needed.

Thanks again,
Paul.


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## Marcel (Oct 21, 2012)

I am sceptical wheter HCl can dissolve the plastic involved. Those materials are usually UL etc. certified and can withstand HCl.
I suspect the amount of H202 that you have added has led to a strong exothermal reaction which - if it exeeds around 100°C will melt the plastic.

If you process pins in plastic housing there is a lot of space between the copper which will lead to a low amount of copper vs. a high amount of AP.
You should try to further reduce the AP or even better, use an old dark one and take a bit of time. Using new AP can lead to this strong reaction which will overheat the plastic. Don´t underestimate that effect.

Btw: I also collect the plastic. i you have large amounts of them, seperate them by color, they might yield more than the gold. Some plactics from industrial or mil. connectors are very expensive. You can tell that by the way they feel when you touch the surface. Expensive one feels and looks like from gun parts etc. where the cheap one feels like from toys.

You can also try to pull the pins, by first warming the pins - not with a hetagun but a hairdryer or a water bath(sometimes odur evaporate, so that is not good for all of them) Then as the plastic gets warm it become svery easy to pull the pins.

Edit: To test the plastic problem, simply put some pur eplastic in the AP without any pins and see if it dissolves/melts.

Concerning the link to the posting with obvious problems with HCl and a motherboard: These white PCI slots are very cheap, lightweight gasfilled materials (foxconn is best at making this low end crap) from china. Maybe the HCl has reacted with the paint from this stuff. Plastic for electronics is sandfilled crude oil.

Marcel


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## GotTheBug (Oct 22, 2012)

Great advice Marcel, and Thank You also!

On a further note, I tried another small test batch with weaker HCl and just left it. Funny thing, ALL the plastic is GONE, as in completely dissolved. Now I have a few pieces of gold pin mixed in with a brownish sludge. I WILL find an efficient way to do this, lol.
As the sludge is very "loose", as in not gummy and sticky as previous test batches, I might try to remove the pins from it, we shall see. The reaction did not produce enough heat to melt the plastic, at least on this last run.

Interesting times....


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## Geo (Oct 23, 2012)

there are different types of PVC plastic. the plasticized PVC will not be effected as bad. some examples of plasticized PVC is the pipes used for water and most five gallon buckets. though flexible,it will break if stressed. rubberized PVC tends to flex a lot more and will bend double before breaking. this is the type that will break down in concentrated hcl. high density plastic HDP is hcl resistant for the most part.


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## GotTheBug (Oct 23, 2012)

Geo said:


> there are different types of PVC plastic. the plasticized PVC will not be effected as bad. some examples of plasticized PVC is the pipes used for water and most five gallon buckets. though flexible,it will break if stressed. rubberized PVC tends to flex a lot more and will bend double before breaking. this is the type that will break down in concentrated hcl. high density plastic HDP is hcl resistant for the most part.



Kinda figured that, especially with recent experience. Ah the learning curve. I am SO looking forward to replacing my profile pic with something more goldenly attractive (new word, use it freely), rather than a representative of my first error. I plan to play with the completely dissolved mess tomorrow just to see if there are any pins recoverable.

Geo, you da man, but you knew that already didn't you.


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