First try at AP process

[zenophryk]

So I went out looking for muratic acid saturday. Home Depot and Lowes has concrete cleaner/etchant but it contained phosphoric and nitric acid, no hydrochloric. So I stopped at my local masonry store, and right as I walked in , on the shelf, 2 1 gallon jugs marked (in big lettering) 31.4% Hydrochloric acid. Sweet. then I just grabbed some 3% hydrogen peroxide and I was off and running.
First batch was a small bundle of fingers in a small plastic bottle. After about 3 hours there were a bunch of foils floating around, but it wasn't finished.
The next batch is going to be either header pins or cpu socket pins. Both of which will have solder on them. So my plan is to let them soak in straight HCl for a while to remove the solder, then put them in the AP. I know it's easy to cement silver out of Nitric with copper, but what about out of HCl?

Also, I made a quick little bubbler tube out of some vinyl tubing and my 35 gallon air compressor, set as low as it would go of course. For the next batch I'll likely be using some actuall lab glass (just ordered) and wand to make a slightly nicer bubbler. does vinyl tubing have good resistance to HCl? or should I try something else?

-Zenophryk

 

[patnor1011]

I have used normal tubing which is used in fish tanks or hospital for iv. If you decided to do pins in AP be prepared that process will take days rather than hours even with bubbler. Do not be tempted to add more and more H2O2 it will only dissolve some of your gold. Be patient and after few days you will see foils floating. Pins will consume considerably more HCl than fingers.
Do not be concerned much about silver. There is very little, almost none on gold plated pins, even less in solder. Silver will not stay in solution, it will drop as whitish/grey precipitate on the bottom and will be somehow mixed with very fine gold from flash plating in form of brownish residue and with whitish powder one form of copper chloride. You will reclaim values from bottom of your bucket this at later stage when you will be disposing used up AP.
Have fun.

 

[Harold_V]

I know it's easy to cement silver out of Nitric with copper, but what about out of HCl?

For all practical purposes, there will be no silver in solution when using HCl. It is not a solvent for silver, although some may be converted to silver chloride under certain conditions.

Harold

 

[zenophryk]

So all the pins I'll be processing will have a little bit of solder on the ends. So is it not worth cleaning that of in HCl first before moving then to AP? I know there won't be a lot of silver in that solder, I'm also doing small batches, so there will be a lot less. but since time is not really a factor, wouldn't that step just make sense?
So the silver won't go into solution with AP, it will just precipitate on it's own, but what about the rest of the metals in the solder?
I'm also getting a fair amount of solder balls when I cut off BGA chips from boards. from what I read, these solder balls have a fairly good silver content. So I figure, why waste the silver, I should find a way to reclaim it.

-Zenophryk

 

[Geo]

you can put the pins through a warm hcl bath to remove solder and thus any silver from the material. note : after the warm hcl bath, the pins will have a copper color. this is often mistaken as the gold being dissolved in the hcl bath. it is a re-deposition of copper over the gold plate, so dont be alarmed at the appearance.

 

[butcher]

Recovering any silver is not a problem; it can even be retrieved from stock-pots, if you do not get it earlier.

The step for removing solder in pre-steps is important, as tin is in most all solder, this metal will give many troubles through-out the processing in many of the steps later, and can cause loss of values (gold) in several ways, and is better dealt with early in your processes, the HCl will break down the solder, lead chlorides and silver chloride (if silver is involved) will precipitate as white powders, tin will usually stay in solution as almost a gel, if tin is left in the process (or carried through your processing steps), it will rear its ugly head and, later this gives trouble filtering, this tin gel can also in-trap fine gold, tin chloride (tin and HCl) forms stannous chloride, so if tin is carried through process to when you dissolve the gold, the tin or stannous in solution will reduce the gold to colloids, causing more trouble in precipitating or even testing gold in solution.

Not removing tin early (trying to save time), will actually slow you down, causing many extra steps later, to deal with something that could have been dealt with much simpler by spending the time needed up front.

Basically get rid of the solder as soon as you can keep it out of your processes it is nothing but troubles.

 

[devo]

I'm still very much in the learning phase, and don't have much to contribute around here. I too use plastic tubing with an air compressor. I couldn't get the regulator to go low enough without making a bunch of foam, but found that I could control the air flow very well by pinching the tube with a small woodworking c clamp.

 

[butcher]

A small aquarium fish tank air pump, works well for me, melt end of tubing together, poke small holes in sides of tube with red-hot needle.

 

[patnor1011]

I'm still very much in the learning phase, and don't have much to contribute around here. I too use plastic tubing with an air compressor. I couldn't get the regulator to go low enough without making a bunch of foam, but found that I could control the air flow very well by pinching the tube with a small woodworking c clamp.

Be careful, that may put unnecessary pressure on your compressor, that very much depend on type. You may be better off to have some divider in place to divide air flow to two hoses - one will go to bucket and another somewhere else. I used small 5e worth chinese fish tank bubbler without any problem. It is worth to remember that HCl fumes are very corrosive and will attack metals in your compressor if it is close enough. I had to replace all my screwdrivers and bits as they used to be close to HCl and after few weeks I found all of them covered in rust. :lol:

 

[devo]

Thanks for the advice. I only mentioned as a temporary solution that works in (pardon the pun) a pinch. I will be getting an aquarium pump soon enough. All my stuff is outside until I get a fume hood built.

See some people do listen to what you guys preach.

 

[zenophryk]

my first "batch" is basically done. i had left it to finish for a few days without a bubbler, and even after 4 days it hadn't completely finished my small batch of fingers. but I filtered what I did have through a coffee filter into another container to reuse the AP and washed everyhthing else down into a seperate container so not to dilute the AP. And I have some foils YAY. not much of course. I'll weigh them tonight just for curiosity. (.15 grams
So the AP I saved off to the second container was relatively black, which I read is good. I added some more fingers (maybe a few ounces, as well as the ones that didn't finish the first time) I also added some more HCl. did not ad any peroxide this time. and replaced my bubler tube (just a single tube with small hole at the end) I will be making another tube today that will wrap around the bottom of the container and have lots of small holes for better airation. But after about an hour or 2 the solution went back to almost clear (slight green color). What's up with that? and it dosn't look like it's doing much. I'm guessing maybe it used up all it's oxygen sitting for 3 days, then I added more HCl but not more O2 so it's waiting for more O2 to disolve? other than that, it's not doing too much.

-Zenophryk

 

[Marcel]

The hints on removing the tin with a hot HCl bath is very useful. Should be standard procedure. I learned this here.
I improoved speed and convinience by putting the pins in a glass with warm HCl inside a ultrasonic clenaer with warm water in it (Do not poure warm HCl into the ultrasonic if it is made of metal! )
It takes 2-3 minutes and all my pins are clean and ready for step II.
What I am asking myself, what ever happens to Palladium in the AP process ?

 

[lazersteve]

Palladium will go into solution with AP. Once the solution saturates with copper the Pd will precipitate out with any dissolved gold.

Steve

 

[Marcel]

Thanks Steve,
Just to be prepared for that saturation effekt:
How will the AP look then (color)? and how the precipitated Pt?
Does that mean the Pt can be precipitated just by adding enough copper?

 

[lazersteve]

Pt is Platinum, Pd is Palladium.

The AP will be dark black/brown when it is saturated with copper.

The precipitated metals will be dark black.

Steve

 

[Marcel]

Thanks again Steve:
is your DVD "Processing Fingers with Acid Peroxide DVD- Video Guide to Processing Plated E-Scrap" treating this matter (the Pd recovery from AP) also or your DVD "Fundamentals of Platinum and Palladium DVD- Video Guide to Processing Catalytics and Other Pt and Pd scrap " ?

 

[lazersteve]

The Acid Peroxide DVD deals exclusively with gold on copper based escrap.

If your AP ends up having a residue of Pd black in the bottom of the liquid after saturating, the same techniques demonstrated for Pd on the Fundamentals of Pt and Pd DVD will work to recover and refine the Pd.

I made all of my DVDs from a standpoint that teaches you the various processes so that they can be applied to any scrap in the order you desire as needed.

Steve