Dissolving rust to free trapped gold

[KevinInColorado]

OK guys, easy question...what's the cheapest way to dissolve rust away? This pic is a pan full of rusted junk I've collected while prospecting. As you can see the rust has had time to bind up lots of other stuff. It's going to be too cold to prospect this week so I guess it's time to dissolve the rust to free any gold. Some of this is from a really rich mountain claim but I still want to be smart about this...no point spending $10 to get $5 of gold now is there!?

 

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[Lookin4goaled]

Soaking it in white vinegar for a couple hours is supposed to work well... I have never tried it myself, just going by word of mouth. You have to scrub it after the soak, and the longer you let it soak the less you have to scrub...

 

[Underburden]

Years ago you could use Coca Cola but I'm sure the recipe has changed.
The magic ingredient was phosphoric acid.
You can currently buy a pretty strong solution at an auto parts store...just ask for aluminum wheel cleaner.

 

[KevinInColorado]

Ok, I happen to have a quart of white vinegar so I dumped it in the pan. Pretty heavy rust layers from 100 years sitting in the creek bed in some cases so I think this will take a while! Btw, coke still has phosphoric acid in it!

I also have sulphuric acid disodium salt, spa filter cleaner - wonder how that might work. Thoughts?

 

[russau]

Years ago you could use Coca Cola but I'm sure the recipe has changed.
The magic ingredient was phosphoric acid.
You can currently buy a pretty strong solution at an auto parts store...just ask for aluminum wheel cleaner.

i doubt that my Coca Cola would work very good and infact it may pzz me off a little. my Coca Cola has to much rum and lime in it to work for this idea! and it would seriously curtail my socially active evening around the campfire!

 

[rodoconnor]

Hey Kevin , you might try an electrolisis bath . I've removed rust from gas tanks that way. Easy to do. just need a battery charger

 

[KevinInColorado]

Hi Rod, I have a car battery charger. Do you have a set of instructions to do it for me to follow (or I can just google it)? This process isn't going to plate the (presumed) gold in it is it?

 

[omnicron]

I tried vinegar...I let it soak for 2 days and nothing!

 

[KevinInColorado]

I found a comment by a research chemist on an auto restoration forum who suggested phosphoric acid and recommended Ospho from the hardware store. I guess if the vinegar fails me, I could try this but am trying to do it on the cheap and if using the Sulphuric Acid spa cleaner is bad for some reason.

 

[TheHarleyMan2]

WD-40

 

[simbad42]

CLR for a half hour. Less dangerous then pool acids, and it's under most peoples counters.

 

[G1sammons]

Don't do ospho it does not remove rust rather it turns rust to a epoxy like finish and it's very hard to remove at that point!

Iv used it much for killing rust on equipment befor painting , when I lived on the coast.. And it great for that but not removing
I would suggest lime away or clr

 

[KevinInColorado]

Ok, really glad to know to stay away from the phosphoric! I don't own any CLR - due to the high quality water here in Denver I've never needed it. Good point about it being safer than pool chemicals...may have to buy some. If I try the sulphuric acid, I will definitely do it outside...which is a challenge right now due to the cold weather here. The cold doesn't just slow me down, it would also slow down the chemical reaction.

I don't think Wd-40 would be a great choice given the thick layer of rust I'm facing and the downsides of ending up with gold just coated in oil. Or am I missing something?

 

[Goldwasher]

NNNOOOOOOOOOOOOOOOOOOOO wd-40......you will not be able to pan and you will make your pan useless... Coka Cola as it is currently made will remove rust but, I don't know how long it will take.

 

[Lookin4goaled]

Sorry if the Vinegar doesn't work Kevin, like I said, I haven't tried it myself, just heard from other people I know that they have used it before and it worked...

 

[NHBandit]

Molasses, which just happens to be one of the "secret" ingredients in Coke and what gives it it's color. It's high in Phosphoric acid but not nearly as aggressive as CLR and will not hurt the metal. It's been used by automotive restoration guys for years. Here are some antique railroad lanterns that I did. They were completely covered with surface rust. 2 days soaking in a 5 gallon bucket with 2 jars of molasses & about 4 gallons of water. Light scrub with fine steel wool when removed just to knock off the film formed by the chemical reaction. Do it outdoors. The smell isn't very pleasant. Well holy hell ! Pictures aren't working AGAIN ...... Tried resizing, cropping, etc. Keeps telling me that a jpg is not a valid file ? I wish they could get this figured out and fixed once & for all.. It's frustrating to say the least. Update.. Waited a half hour and came back to this post and now pics are working ? I didn't change a thing, just decided to try it one more time. Weird. I think T-net is possessed by evil spirits.. Anyway... this is what rusty lanterns look like after a 2 day soak in molasses & water.

 

[rodoconnor]

Just google it kevin or Youtube . You will need 2 dissimilar metals. Copper pipe iron pipe.As far as it causing gold plating--don't know. I think maybe that your Au has to be in solution. Someone onTn should chime in.

 

[stanjtown]

Years ago I did aluminum anodizing which requires an electrolysis bath that is a 50-50 mix of battery acid and distilled water. This would work to remove rust but I think it will also remove the gold as well. The way it works is you need one anode for the negative and you make your part the positive or it could be the other way around its been awhile. The down side is that it split the hydrogen and oxygen and will build up, if not ventilated properly it could explode so be careful where you do it. I had a fresh air intake and an exhaust fan run the hole time the bath was running and for a half hour after. then you have to neutralize the acid bath with baking soda and then dispose of it. I had a 50 gallon bath and it took I think 7 - 10 lbs. to neutralize the acid. "Not very cost effective" as well as dangerous and not something that you want around if you have kids which is why I got out of it when my son started to help me in the garage to work on thing.

PS. you also need a wash down area to rinse off the parts and a way to neutralize the water that has acid in it so it wont hurt the environment as well.

 

[NorCalPilot]

Dumb question-- I tossed out iron junk like that on Sunday while detecting including a 6 inch nut and bold... you're telling me it might hold gold?

 

[KevinInColorado]

Well if the rusting process occurs down in the bottom of the creek bed, the rust binds whatever is next to it into the rust matrix. In my rusty pieces, you can see pebbles trapped in the rust. Since this stuff is from the bottom layer of gravels in gold bearing creeks, it may have gold trapped in it...all the heavy stuff tends to end up in the same parts of the creek bed right? So, it's time for me to find out!

At the moment it is soaking in vinegar with sulphuric acid added to it when the vinegar acid seemed to run out. An experiment for sure.