PINS IN AP

[andees78]

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

 

[Harold_V]

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

 

[andees78]

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

 

[Geo]

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.

 

[Harold_V]

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

 

[Emmjae]

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

 

[rewalston]

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

 

[Geo]

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.

 

[NoIdea]

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

 

[rewalston]

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

 

[Palladium]

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?

 

[Geo]

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.

 

[rewalston]

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

 

[andees78]

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?

 

[TXWolfie]

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.

 

[andees78]

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

 

[Geo]

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.

 

[andees78]

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

 

[Emmjae]

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

 

[andees78]

thanks Mike