Processing of copper pins after incineration of chips.

[yellowfoil]

Dear friends, I have incinerated pounds of chips and I need to process copper pins after separation of ashes. I managed to knock off all gold bonding wires from pins in paint shaker and sifted out almost all pins. Paint shaker is by my opinion superior to processing ashes in mixer, because all dies and unburned plastic stays intact and is easily separated for further processing. All long gold bonding wires crumble into balls and mostly will get through sifter. Pins just after five to ten minutes of shaking are surprisingly clean and ready for processing. I have to mention that I added good amount of water before shaking and sifted out pins wet in water bath. Then pins went back to shaker with clean water few more times, till I didn’t see any gold wires connected to pins. Unburned chips, dies and other debris are separated after first shaking.



This is my way how to deal with burned chips and now I am looking for way how to process these pins. My idea is to melt those pins into bars and use them for cementing or for waste processing. I noticed that most pins have spots of soldering remains, most likely contain some precious metals and should end up in the sludge after cementing or waste processing. I would like to know anybody’s opinions about this approach and the most importantly, what flux to use when melting copper pins. Thanks for any direction in this mater.

 

[Martijn]

Good plan.
Imo no flux needed to melt metal. A bit of borax never hurts to absorb some oxides.

Stockpot will be your best option if not too many other base metals in there.

For clean cementing of silver I would use clean copper.

 

[yellowfoil]

Thanks Martinj for your input.

I am sure you are familiar with nonmagnetic pins from chips. There are some other metals than copper, mostly brass soldering and leftover tin solder, but not in large quantities. I am not sure about copper alloy of pins. By my opinion it should be mostly copper, so I hope that it will work OK in my stock pot. I am trying to find work around nitric acid for now, because it is prohibitively expensive in Canada and not readily available. I leave all processing, including silver which requires nitric, for later time when I will be able to make my own, except gold processing, where there is no need for large amounts of nitric. I have bunch of sterling and silver contacts, but not willing to burn $60/L+ of nitric on it.

I have Italian made melting furnace, GF1100ND 850W with graphite crucible. Is graphite OK for melting copper. Thanks again.

 

[Martijn]

For an electric furnace graphite is good. Don't use borax in it. It will eat the crucible.
Graphite has reducing propeties so only melting metal and no smelting of oxides in flux.

 

[Martijn]

If you have gold foils, you can dissolve them with HCl and drops of bleech. No need for nitric.

 

[yellowfoil]

Thanks Martijn.

I am aware of HCl bleach process, I use it for striping of gold from glassware, but it is too slow for anything else than glassware. I have some HNO3 for gold processing, so for now I am OK.

I was going to use borax in my graphite crucible, but after your advise I will not. Thanks again.