Electrochemistry Types of metals in reverse electrolytic cell

[niteliteone]

I'm trying to buy some gold plated scrap metal and aluminium. All heavy plated machined parts from military and NASA type scrap.

I am hoping to use the reverse electroplating process to remove the gold.
My concern is what types of metal should I keep out of the sulfuric acid? :?:

The load contains copper, brass, aluminium and possibly other metals.
I know the copper and brass are OK in the cell, but how about the aluminium? :?:

Any input would be appriciated especially on the aluminium :shock:

Thanks
Tom C.

 

[kuma]

Hello , how are things today?
I hope that your well!
You may have already seen it , but just incase ; http://tinyurl.com/d6zwzz7
The thread is a duscussion about gold plated aliminium , here GSP says " the H2SO4 stripper works quite well for gold on aluminum."
I hope this can be of some use to you! :mrgreen:
All the best and kind regards ,
Chris

 

[niteliteone]

Thanks kuma.
I read your reply but was in a hurry to go meet the seller and try to agree on a price.

Well the guy changed his mind and decided not to sell the scrap to me but instead asked me to recover the gold for him.

He liked my upfront honesty on how low a return he should expect and how I explained to him how to approximate a return value for gold plated material. (I used the formulations from GRF handbook vol.1)

Every other refiner he tried either assured him of high values then returned peanuts or would never be heard from again. So he gave me a small bin (around 25 lbs) full of assorted material to see how close my guestimation would come to what I actually recover.

I did all the numbers in my head and basically used the guesstimate of .1% return for low mass heavily plated material to .01% for more dense (thicker) material. It averaged out to 12 lbs high grade and 13 medium to low grade, about even.

So my math was:
25 lbs x .05% return = 25 x .0005 = 0.0125 lbs = 5.6699g x $1630 spot = $296.87

A little low but it is easier to give the customer more than expected later than try to explain why it was less than expected. Especially since we will split the money 50/50 on this load only. Then 80/20 thereafter if he likes my work.

The bin contains various types of scrap (pictures below) that makes it hard to estimate a return value so all of it is just a guess for me no matter what formulas I use. So far I have always come out ahead with the few pieces I bought in the past, mostly escrap. I will post the starting weight and return weight of each item I show in the pictures as I recover the values if anyone wants to see that information.

Time to ge to work.
Tom C.

 

[ryobie1]

I did some gold plated aluminum jump rings today in my sulfuric cell and didn't notice any contamination. If you leave the aluminum in the cell it turns nasty.

Be carefull with magnesium! With military stuff you just never know. Gold plated magnesuim is very popular with nasa and air force.

As you already konw. Read as much as you can about any materials you plan to use in your cell.