Dissolving stainless without dissolving gold

[Mcnew32(Ag)]

Hey guys, made the mistake of not allowing enough drop time for the gold bead to cool before hitting the bottom. As you can see the gold stuck to the stainless. My question is what is the quickest way to dissolve the stainless away from the gold. Or would it be easier to just dissolve the gold back from the stainless? Please let me know.

 

[jason_recliner]

There are different types of stainless steel. I would test a separate cutting first in hot HCl.

 

[Platdigger]

Once you have determined it will dissolve in hcl I would trim it up a bit closer to the gold so it does not take so long.
It most likely will dissolve in hcl, but slowly.

 

[jimdoc]

I would use a propane torch and melt the gold off.
Propane won't be melting steel.
Or bend it and get a screwdriver under the gold, twist and pop it off.

Jim

 

[g_axelsson]

Hit it with a hammer and flatten the gold out. As gold is a lot more malleable than stainless it will put stress on the weld and hopefully break it cleanly.

Göran

 

[Anonymous]

I would use a propane torch and melt the gold off.
Propane won't be melting steel.
Or bend it and get a screwdriver under the gold, twist and pop it off.

Jim

I'm with Jim on this as a first step. If you're left with some that won't budge then I'd Plat, and Jason's advice and trim it back and leave it soaking in HCl, eventually the steel will dissolve. You'll want to re-refine it all at any rate.

I never pour gold into Stainless containers for this exact reason, but as more than one moderator and member has pointed out historically- it's a mistake that many of us have made in the past so it's really just one of those milestones in the learning curve. 8) 8)

No dramas, merely onwards and upwards.

Jon

 

[goldenchild]

Dropping into a stainless container is fine. The depth of the water is what's key. You have to have enough depth so that the molten metal cools enough so that nothing happens when it hits the stainless. Hell, I've shot molten metal into a 5 gallon bucket with a glass jar to catch it.

[youtube]https://youtu.be/e-WJZpxAqvI[/youtube]

 

[Anonymous]

Yep I hear you goldenchild, and I agree with you. I just prefer not to add a potential problem if I don't need to. If the potential of bonding the gold to SS doesn't exist in any shape or form then it can't happen can it?

 

[Mcnew32(Ag)]

Thank you guys for the replies. I'll keep you updated on what worked.

 

[j2000]

i prefer melting the gold only than stainless.....
As i know SS is have more high melting point than iron...
Melt the gold only with good 2 torch butane such turbo torch..but this lil hard to melt i think... or
using welding torch (acetylene or lpg and oxygen)....slowly move the torch until gold melting but dont melt stainless...
Btw, I often release bonding the copper and iron with fire (torch oxygen plus butane) or using induction melting furnace is more easier..
Using induction melting furnace just put empty graphite crucibel with your SS, set the power factor where IT CAN melting the iron on the furnace, hold your SS with gold with pliers...waiting your gold release from SS...

 

[upcyclist]

I would definitely go with physical methods before chemical methods, because chem methods could introduce other impurities. Note that melting itself is physical, but the fuel (dirty flame) you're using might involve some chemical interaction.

Another random (as in "might not work") thought: try throwing it in the freezer. If the steel and gold contract at a different enough rate, the gold will pop off by itself.

 

[Lou]

Dissolve it all. Refilter, re-precipitate.

Problem solved.

Otherwise...30% sulfuric with 20 g/L NaCl.


Lou

 

[j2000]

Dissolve it all. Refilter, re-precipitate.

Problem solved.

Otherwise...30% sulfuric with 20 g/L NaCl.


Lou

Lou, u mean u do recovery gold from ss from beginning by chemical?

 

[Harold_V]

Base metals that have gold soldered to them are most likely to contain traces of gold, as molten gold is a solvent of other metals. For fully recovery, dissolution of the entire mass is suggested. I would, however, eliminate as much of the base metal as I could, using dilute sulfuric, as Lou suggested.

Nothing wrong with using stainless as a receiver for making shot. Just make sure of a few things. One is that the water is quite cold, and that the stream not be poured in one location only. That leads to localized superheated water, which will flash to steam, resulting in the molten gold losing contact with water. You can circumvent that problem by icing the water (assuming you have an abundance of gold to pour) and moving the stream about. Alternately, you can put a small pump in the receiver, which will simply circulate the water. That limits the molten gold from creating a steam path.

The largest amount of gold I melted and poured to shot was right at 400 ounces. I started with about five gallons of water (in a stainless vessel), iced, and circulated the water with a small pump, as I advised. No problems to report.

Harold