# PINS IN AP



## andees78 (Aug 11, 2011)

Hello Eeryone
Last night, I put about 1 pound of close cut pins in 1/2 litre HCL 38% and poured like 10 ml 0f 3% peroxide, to start the operation. the solution was clear, then pale yellow, then pale green. i understand it should take some days as this nearly straight HCL. *This morning i found the solution is colourless with red brown dust cemented on the pins.* i poured another 10ml peroxide and it turned pale green. The weather is already hot here so i didnt use a hot plate like most of you do.
Please explain and comment.
thanks


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## Harold_V (Aug 11, 2011)

A long shot, but a possible reason-----pins are made of brass, which contains zinc. I'm of the opinion that there was enough zinc present to cement the small amount of copper and gold that had been dissolved. That would account for the red powder you witnessed. 

Harold


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## andees78 (Aug 11, 2011)

Hello Harold
Thanks for the reply. how do you suggest i proceed from here, should i change something?


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## Geo (Aug 11, 2011)

for processing pins in AP you have to have a supply of oxygen to keep the reaction going.i would suggest aerating your solution with a air pump from a fish tank.use a bubbler stone,opinions vary on which color stone holds up the best.after starting the bubbler your soltion should turn green and get darker and thicker as time goes along.the whole process should take 7-10 days.


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## Harold_V (Aug 11, 2011)

andees78 said:


> Hello Harold
> Thanks for the reply. how do you suggest i proceed from here, should i change something?


You'll have to rely on input from others. I have no experience with the process in question and don't want to say anything that may not be true. 

Harold


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## Emmjae (Aug 11, 2011)

Geo said:


> for processing pins in AP you have to have a supply of oxygen to keep the reaction going.i would suggest aerating your solution with a air pump from a fish tank.use a bubbler stone,opinions vary on which color stone holds up the best.after starting the bubbler your soltion should turn green and get darker and thicker as time goes along.the whole process should take 7-10 days.



I don't use a bubbler stone anymore....They don't hold up at all and when they start degrading it leaves a mess in the bottom of the bucket.

I just seal the end of the tube with my torch and then heat the tip of a paper clip and burn a dozen or so holes in the tube itself. Works like a charm for me.

Mike


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## rewalston (Aug 11, 2011)

A quick question about AP. If I remember correctly, IF (a big if there) you have some solder on your pins (desoldered rather than clipped) AP will remove the solder as well won't it? I know the goal here is to separate the base metals from our gold and then filter and rinse, etc. And then proceed onto HCL + CL. Am I correct in my assumption? I have a few pins that I just heated the solder on the back side of the board and then pulled the pins from the plastic housing, they were a little too think to just chisel off the front of the board and pluck them from the housing. Everything else I have will be chiseled and pulled so they should have little to no solder.

Rusty


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## Geo (Aug 11, 2011)

if you have solder it shouldn't be too big of a problem. it takes quite a bit of tin in AP to make a big mess.it will make tin (II) chloride in small amounts but in large amounts you can get Tin dioxide which will precipitate out during digestion as a white crystal that is insoluble in water (it looks like sand) and can trap your gold.


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## NoIdea (Aug 11, 2011)

Morning All – Has anyone tries pumas, being volcanic glass it should hold up very well. It would pay to repeat boil it in acid/water first. I have bin meaning try it, I use a scintillated glass one.

Deano


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## rewalston (Aug 11, 2011)

Geo said:


> if you have solder it shouldn't be too big of a problem. it takes quite a bit of tin in AP to make a big mess.it will make tin (II) chloride in small amounts but in large amounts you can get Tin dioxide which will precipitate out during digestion as a white crystal that is insoluble in water (it looks like sand) and can trap your gold.



Thanks Geo, right now I haven't a clue as to how much I have, the only scale I have is one for the kitchen, I think it only goes down to .1gm if I'm not mistaken. If I had to guess about the pins I had to desolder, there is probably about 31gms or so, not enough to screw around with but I'm getting there slooooowly. Now all I have to do is figure out where I put my chisel so that I can sheer the pins off the top of the board, don't mind pulling the pins from the blocks. For fingers I've just been snapping them off with a pair of pliers so they look really ragged. I don't have anything sharp enough to cut them so they look as nice as what I've seen here on the forum. But I've made sure that there is no SM components and no solder that I can see, just a little bit of board.

Rusty


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## Palladium (Aug 11, 2011)

The correct ratio of hcl to H2O2 is 2 parts Hcl to 1 part H2O2. If you use 1/2 liter of Hcl then you need to add 1/4 liter H2O2. Then use air on top of that. Solder is a pain in the butt. Try soaking them in straight hcl with no air to remove the solder first. 
When the oxidizer is gone from the solution metals want to plate back on the pins. When you add H2O2 it turns green because of the oxidizer you added. Did you notice when you added the H2O2 if the pins came clean again only to see the same thing happen again later?


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## Geo (Aug 11, 2011)

something to think about.some pins are goldplated all the way to the end.if you cut them from the board you are leaving a certain percentage of your gold behind.when i can i sweat the connectors off with a pen torch (dont breath the smoke,it is toxic).if im in a big hurry i use my propane torch and make a few sweeps over the back of the board and tap on it with a small hammer,as the solder breaks loose the components fall off the front.elevate the board using bricks at the corners.this is a very fast method and is sure to get all the pin out of the board.also i use small chisels and screw drivers to pry the plastic off the connectors before hand, this keeps from melting plastic and lets the pins fall freely. as for the fingers i use a set of aviation metal shears but any sheet metal shears will cut boards very smooth.


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## rewalston (Aug 11, 2011)

Thanks Geo, the only thing I have is scissors...too hard on the hands. I was prying the plastic off first but thought the other way might be better, I guess not :lol: I'll keep on keeping on the way that I was. Thanks again.

Rusty


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## andees78 (Aug 14, 2011)

Hello
Thanks everyone.
Yes Palladium i noticed that.


> Did you notice when you added the H2O2 if the pins came clean again only to see the same thing happen again later?


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## TXWolfie (Aug 14, 2011)

Ok talking about air stones from fish tanks, I remember they used to sell plastic airstones and also make what is call plastic air diffusers they are basically the same as stones just do a google search or check your local fish store or Walmart will probably have them. Ijust dd a google search and yes they are still available.


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## andees78 (Aug 15, 2011)

Hello
Palladium, Mike, Geo
i poured 230 ml peroxide in the solution. and Mike, i used your suggestion, i sealed the end of the tube in an aquarium pump and made small pin holes on the end. 
The solution turned green and started getting darker and hoter. Then foils started swiming. *but after one hour the solution started to get paler.* i didnt leave the pump over night for safety. the solution now is pale green with foils and brown dust on some pins. please advise.
regards


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## Geo (Aug 15, 2011)

just as before, when you remove the oxidizer metals plated back to the pins.start the air bubblier back and maybe add a little more H2O2 to start the reaction again.air pumps for fish tanks are made to run continually. not sure what safety concerns you may have but when you stop the air supply the reaction will stop and it will take longer to finish the process.


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## andees78 (Aug 15, 2011)

Thanks Geo
but why did the solution fade even when the pump was running?
will the solution bear all the base metals?
regards


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## Emmjae (Aug 15, 2011)

Green is a good color. As the solution becomes more saturated with copper it will turn brownish in color. This is still ok as long as you keep the air supply going. The air bubbles will keep the solution under control as it dissolves the copper.

If your ratio of base metals is more than the solution and air can handle it will turn a very deep dark brown like chocolate milk. Don’t panic, just add some more muratic acid and let it continue until all the base metals are dissolved. I usually add about a third of what I started out with. If you really overloaded the solution to start with you may have to do this a couple of times along with a little more 3% peroxide. Just let it do its work for at least a day or so and see how it looks before you add muratic acid again. When you overload with base metals it slows this process down quite a bit.

Once the base metals are all dissolved and you have filtered off the solution, pour off any excess you don’t want to keep and dispose of it properly. Put the air bubbler back into the remaining solution. It will refresh it back to a nice green color and be ready to use again in a day or two. I am still using my first bucket of AP and it’s almost 1 year old.

Mike


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## andees78 (Aug 15, 2011)

thanks Mike


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## patnor1011 (Aug 15, 2011)

When you have lot of tin in auric chloride solution your solution will be yellow but when you attempt to drop gold with SMB you will get dark brown/black solution which will refuse to settle. I have one jar with dropped gold say about 4 days and only small part 1/5 is clear on top, rest of gold still hang in solution. I did this just to see how long it will take. If you want to speed up things you will need to heat that solution to slowly evaporate liquid. As it will become hot your gold will settle on bottom faster. Melting this powder will result in silvery button. I recommend to just incinerate powder and put it in fresh HCl to get rid of tin.


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## andees78 (Aug 17, 2011)

hello everyone
the solution is now 2:1 HCl:H2O2. The air pump is running continuously.
it is still very pale green after 36 hours, is that normal color or am being impatient?
regards


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## Geo (Aug 17, 2011)

andees78 said:


> hello everyone
> the solution is now 2:1 HCl:H2O2. The air pump is running continuously.
> it is still very pale green after 36 hours, is that normal color or am being impatient?
> regards


yes, pale green is good for 36 hours. the whole process will take 7-10 days. depending on how much material you are working with and how much liquid you have, the solution may never saturate with copper. after you do this process two or three times you will learn what to expect. its my experience that it takes 1 and 1/2 US gallons of acid to digest 1 US pound of pins in 7-10 days depending on the weather. hotter weather equals less time. i dont heat my solution but some others do.


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## andees78 (Aug 17, 2011)

thanks Geo, 
i read somewhere that diluted HCl is better,
is that true, and how much diluted?
regards


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## patnor1011 (Aug 17, 2011)

andees78 said:


> thanks Geo,
> i read somewhere that diluted HCl is better,
> is that true, and how much diluted?
> regards



I don't think so. It will be working but it will take longer. I use 10-20% HCl as I cant get the proper stuff. Maybe you confused this information with diluted nitric which is 70% HNO3 diluted to 30-35%.


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## Geo (Aug 17, 2011)

it is true nitric acid will dissolve the brass in the pins faster but it is much more expensive than hcl acid because of the volume needed. it takes 1 US gallon of 70% nitric acid to dissolve 2 US pounds of copper and if you dont have a reflux on your apparatus to collect the nitrogen dioxide to convert back to nitric acid your process will become very expensive very quickly. hcl acid on the other hand is fairly cheap to purchase and can be re-used over and over again without special equipment.


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## andees78 (Aug 18, 2011)

thanks for replying


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## andees78 (Aug 18, 2011)

hello
are the square pins harder to dissolve? 
because all of them are still goldish, and all reactions seems happening
to the little slim ones from ram sockets :?: 
regards


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## Geo (Aug 18, 2011)

that just means the plating is thicker on those pins, not to worry, the reaction is taking place under the gold foil where you cant see it.


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## rewalston (Aug 18, 2011)

Geo, quick question on pins. The pins from within ribbon cables, they are only partially plated would these be better to use a gold cell or AP?


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## patnor1011 (Aug 18, 2011)

My choice would be cell. Amount of gold on them will not be worth hassle and cost of chemicals by dissolving them whole.


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## Geo (Aug 18, 2011)

cell. absolutely, as a matter of fact i dont use AP for pins unless im just way behind. you really need to stay with a cell when operating and with AP you just set it and leave it alone. i can run about 5 US pounds of pins through my cell in a few hours and reclaim 85%-90% of the gold on the pins. i always go back through my pins and pull out the pins that didnt strip all the way. there are always some that dont strip due to bad conductivity or unclean pins (oil or other deposits).


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## rewalston (Aug 18, 2011)

Thanks Patnor and Geo. Now all I need to do is get the materials for EVERYTHING. Still doing a lot of collecting and pre-processing but it's slowly coming together.

Rusty


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## andees78 (Aug 22, 2011)

Hello All
the solution is getting darker green. there is white dust on the bottom, although the
pins where free of solder. :?: 
regards


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## old thompson (Sep 23, 2011)

andees78 said:


> Hello All
> the solution is getting darker green. there is white dust on the bottom, although the
> pins where free of solder. :?:
> regards



I can't answer your question andees78, but would like to hear it if someone else can.

I started my second, larger batch of pins in AP with an air bubbler a week ago, about 200 grams in a 600ml beaker. When the white dust (salt?) builds up as it has been the last three days I have been adding more HCl, about 25ml a day. The beaker is full up to about 450ml, the level of AP is about the same as when I started because I am using a 100watt warming pad underneath and it is slowly evaporating. I suspect that the pins might take another week to disolve, but can I just keep adding acid? Adding a drop of water does not form a white cloud, so I do not think the solution is saturated with base metals, but it is dark green/brown. Should I pour some of it off through a filter to add more fresh 32% HCl?

Of course, the pins are mostly kovar and I should have tried nitric. Thanks-O.T.


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## Geo (Sep 23, 2011)

the composition of the base metal will shed light on this. brass is an alloy of copper/tin in different ratios depending on the application of the metal involved. some alloys have more tin and others dont. the whiter the brass the higher content of tin. the white dust is more than likely tin(II)chloride from the tin in the brass.


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## Harold_V (Sep 24, 2011)

Geo said:


> brass is an alloy of copper/tin in different ratios depending on the application of the metal involved.


Uhhh---no, it isn't. Technically, brass is an alloy of copper and zinc. The line gets real fuzzy, however, in that there are alloys that contain both zinc and tin, and may be addressed as brass or bronze (which is the alloy that contains copper and tin). 



> the whiter the brass the higher content of tin.


You can't generalize that way. There are bronze alloys that are quite white that contain no tin at all---aluminum bronze, for example. In addition, yellow brass has no tin and is quite light colored. It contains 33% zinc.

Harold


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## patnor1011 (Sep 24, 2011)

Pins are (or say that most of them) tin plated - there is thin layer of tin on them anyway. To keep solder out brom base of pin is just reducing raio of tin in your solution and making things easier. Your white powder may be copper chloride.


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## Geo (Sep 24, 2011)

for some reason i always have tin in my solution from pins, even if there's no solder. not sure if bronze is used in the composition of the pins or its used as a shield to keep the gold from migrating to the base metal but the tin is always present. sorry about not making the distinction between brass and bronze. even though i have dealt with bronze in my scrapping days it almost always went into the brass unless it was a large piece like an impeller or propeller and its just a bad habit to refer to bronze as brass.


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## Harold_V (Sep 25, 2011)

I experienced the phenomenon you spoke of when I processed escrap, which was only on rare occasions (only for myself). I can't help but wonder if, maybe, some of the trouble comes from zinc. 

Regardless of the source of the problem, one thing that worked for me, and saved me on many occasions, was to incinerate after processing with nitric, then to give the solids a prolonged boil in HCl, then to rinse until the solution was free of color. Regardless of what the problem material is, it should no longer be troublesome. Please understand, I'm speaking from the perspective of filtration, and nothing more. I found some solutions bordered on the impossible to filter, which I attributed to the presence of tin. Maybe it was, and maybe it wasn't, but the process worked. 

The plating found under gold is typically nickel, which is there to prevent migration of gold in to the base metal. That phenomenon is well documented. 

Harold


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## NoIdea (Sep 25, 2011)

Geo said:


> for some reason i always have tin in my solution from pins, even if there's no solder. not sure if bronze is used in the composition of the pins or its used as a shield to keep the gold from migrating to the base metal but the tin is always present. sorry about not making the distinction between brass and bronze. even though i have dealt with bronze in my scrapping days it almost always went into the brass unless it was a large piece like an impeller or propeller and its just a bad habit to refer to bronze as brass.



Some pins are indeed brass or something similar, dicovered this when using nitric acid on solder free pins, yup, tin said hello to me.

Deano


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