If AP gets to hot?

[MEANIE]

If AP gets to hot will it use up all the oxygen and stop working?
Here is what I did. I did a test on 2 gold plated jumper pins in AP.
IT worked great I got real nice gold foils, so then I prepared 100 of them,
Added them to 300 ml of HLC and 150 ml of H2O2. They was bubbling and eating away at the end of the pins(good so far light green) next day still working,(darker green, eating the brass up)
then the next evening when I got off work I checked on them. They had copper cement on the out side of the tubes and appeared to have dissolved some of the foil and it was clear. I added a little more H2O2 and it went light green fast and bubbled.
I tested with stannous and it was negative. Oh it was 104 outside temp here.
so my question is did it get to hot to change the reaction or stop it?

thanks Todd

the pics are from the test but these are what I am working on

 

[Geo]

you didnt use enough hcl for the amount of material you had. if the base metal is brass, theres a lot of zinc in the mix. you may need to replace the solution and start over. i doubt the gold would have dissolved without a strong oxidizer.

 

[chlaurite]

FWIW, I've had a batch of 100g of mixed mid-grade pins running in AP for a while (over SIX WEEKS - Believe the graybeards around here when they say not to do pins in AP :mrgreen: ). Every weekend I give it a good cook (in a sand/water bath - I very much do not want to see what happens if you crack a beaker full of hot AP) and hold it at 80-85C for a few hours.

Two weeks ago it finally went black (or darkdarkDARK greenish brown, I suppose) - I suspect until that point the acid kept busy with the zinc and tin, then finally ran out of those and started working on the copper. Then, last weekend I started getting CuCl precipitating out as a white sand at the bottom. Funny thing - When I take it off the heat, I get nice feathery crystals of CuCl that end up filling about a third of the container; by morning, as oxygen does its thing, they convert to CuCl2 and go back into solution, leaving just a thin layer of the white mud in the bottom.

So as far as I can tell, heat won't hurt your AP. It can, however, drive off all your nice HCl, if you don't (LOOSELY!) cover the container while hot.

(Any of the experts around here, feel free to correct me!)

Beautiful pins you have there, BTW - What did they come from, if you don't mind my asking?

 

[Marcel]

This starts a very uneffective cycle. Your gold is dissolved and precipitates just seconds later on the outer layer of your remaining pins. It takes enourmous amounts of HCl and H2O2 until all material is dissloved. Nice for learning but no economic sense in this. It is waste of chemicals. The gold dissolving starts even at roomtemperature. H2O2 should only be used as a kickstarter, never added later in teh process. Use only minimal dose and strength.

 

[pgms4me]

hello: I did some of those pin plugs .They were from a mid 1980's video control station removed from a tv station. I used a sulfuric cell and they stripped completely and quickly(about 10 seconds each). I did them individually in a small 12 ounce beaker of 96% sulfuric.. lead cathode on one side connected to the negative ,and the pin suspended (submerged)in the acid and connected by a clip lead to the positive. Voltage used was 5 volts dc from an old computer power supply with an ammeter in series so i could stop when the current dropped. Lowest cost way to process these because of the huge amount of brass alloy base metal.I did about 100 of them before solution temperature rose to 120 degrees f.

 

[MEANIE]

Mr. Geo Thank you. you answered my question.
How is your wife doing ?

Mr chlaurite Thanks I have a mess too you gave me insight.

Mr Marcel Thank you. You told me what I didn't want to hear but the truth . And what I needed to know. I see the ap method is not a good way to go even though it worked great on a few pins. The pins came from a jumper that I was told was used by southwestern bell in my home town in the 60 and 70s

so today I wondered how I was going to do these and pgms4me posted

Mr. pgms4me Thank you Sir. I never used a cell and I don't know much about them. But this is a great place to read and learn. I believe you got me on the right track. Bad thing is you opened another door for me sent me down another path of learning. Made me think of a million questions on using a cell.
I am going to try to do it as you said but I need to learn some more first. For I have about 2 to 3 thousand of these to do, One at a time seems very daunting to say the lease. Sir if you don't mind I have a few questions. What was metal the clip you used to clip the pin on made out of? Do they strip off as foils? and was the yield very good?

Thank you all very much for responding to me.

Todd

 

[Geo]

MEANIE, she is doing great, thank you for asking. it was a very scary time and thank goodness it all worked out.