# Introduction and practical puzzle



## stickle (Jul 31, 2019)

New to this world and not a chem major so...be gentle.

I submitted this to one of the moderators but later thought that this would be a good problem for the whole community.

My In-laws lost their home in the Paradise CA wildfire back last year. They had about 40 pounds of 90% silver coins stored in plastic tubes and in a "fireproof" safe (pre-64 half dollars, quarters, and dimes). When we got access to the site a month later, we were able to recover the safe. Inside the coins had been glued together into a black mass by the melted plastic from the tubes and the interior of the safe (the coin metal did not melt). My first attempt to recover this mess was to cold soak the mass with dry ice and bash it with a 2X6 to bust the coins loose. It was of only limited success. Since then I have tried solvents, heat, cold, black magic and wishful thinking to get these things apart and clean. (Pictures are available.) The dimes are the worst in that they are stuck in groups of five to twenty coins glued together by black plastic. 

I saw a video of someone that "cemented" out silver from sterling and it got me thinking. Further research led me to some of your posts. 

So my questions; would it be practical to use this process to recover the silver from these coins? How can the "trash" (plastic contaminates) be discarded? Could a non-chem major successfully do this? Is it cost-effective at this scale? What would chem cost and "silver cell" costs run? How much silver would be lost (I have been offered sixty cents on the dollar by weight but wanted to explore better options for my in-laws.)

Should I melt the mass first? When heated the plastic just smears worse, but I have not tried to completely melt one. Would the plastic burn off?

The other option is to remove the plastic and save the coins, but I have not had any luck doing so and solvents have not solved the problem. Am I missing something?

Save me Obi-Wan... you're my only hope

Thank you for your time


----------



## nickvc (Jul 31, 2019)

Welcome to the forum and my commiserations to your in-laws for their loss.
In honesty why use chemicals when the plastic will burn off, exposed to air most plastics will burn and crumble allowing you to simply remove the coins from the residue, they might not be perfect but as they were saved for silver value it doesn’t really matter as the value is still intact.


----------



## anachronism (Jul 31, 2019)

Hi there

If you research the type of plastics used for the style of coin packaging you have there is usually a table of particular solvents for different plastics types. 

Did you do this or did you just try the usual suspects? It might be useful if you didn't do it. 

Jon


----------



## snoman701 (Jul 31, 2019)

Just burn/melt the mass unless there were coins valued for more than their silver content...even then, they are pretty nasty now. 

I’m sure there are plenty of people on the forum that will pay you out on the silver, even with a little plastic attached. 


Sent from my iPhone using Tapatalk


----------



## stickle (Jul 31, 2019)

Thanks to everyone for the help.

Regarding the plastic... the problem is it is a witch's brew of whatever was present in the safe at the time including coin tubes, the safe liner, other cases, and ziplock bags. The safe was hot for days, (they never fought the fire in the town, just let it burn itself out...17,000 homes!) I did multiple soaks in strippers and solvents, sometimes for more than a week. Nothing.

How hot can I heat the coins before they deform? Is that hot enough to burn off the plastic? Someone brainstorm a procedure to do this safely. 

I was afraid that if I melted this mess, I would just end up with a bigger, contaminated mess, and a "90%" mess at that. 

Clearly, I have found the right group of people to find some answers. Keep the ideas coming!

Thank you again.


----------



## peter i (Jul 31, 2019)

The small boxes for coins are typically polystyrene. They will soften in acetone (soak them).

Plastic pockets (older ones) may be PVC, making burning and dissolving nasty business.

Polyethylene is very hard to dissolve.

Start out with acetone and a jar/ bucket/ barrel with a good lid and some patience.
(And start small, until you know what works)


If you only want the metal, a small bonfire may be the answer (the coins are not likely to melt).
At a low red heat, all plastic will be gone.
But the coins Will probably be black from oxidation. They will get silvery from a bath in hot citric acid solution or dilute sulfuric acid, but they will not look “fresh from the mint” anymore.


----------



## jimdoc (Jul 31, 2019)

I think I would try putting chunks in a shop press, or maybe even a small vice to try and break the plastic apart and maybe loosen the coins.

Can you post some pictures?


----------



## ION 47 (Aug 1, 2019)

I recommend using open fire as a last resort. You can try to lower the coins in a highly heated solvent (for example, dimethyl sulfoxide, in Russia it is sold in a pharmacy called "Dimexid", worth a penny). Plastic should move away from the coins, you can try to wash the coins in highly heated engine oil (temperature about 250 degrees Celsius).


----------



## snoman701 (Aug 1, 2019)

Was it junk silver or rare coins? Total value of silver? Too much work if it’s just junk silver. 


Sent from my iPhone using Tapatalk


----------



## stickle (Aug 1, 2019)

44 lbs of 90% coin silver is almost 600 ounces of silver, almost $10,000. Not worth it? :shock: 

The hot oil idea seems manageable to me. Could others here give their opinion on that idea? Would it need to be agitated? That is a lot of weight to stir around in really hot oil. 

Just after I recovered the coins I tried something like this with one small sample using peanut oil (high smoke point cooking oil). The plastic did become soft but sank to the bottom of the pan where the coins were. I ended up with coins more evenly coated with plastic and a pan full of plastic soup, and a mess. Engine oil? Break fluid? 

The coins were in good shape before the fire but have lost any collector value because of the damage. I am just trying to recover as much value for my in-laws as I can.


----------



## snoman701 (Aug 1, 2019)

I didn't realize you had posted weight.

How much is your time worth? 

You haven't lost any silver value unless they were rare coins.

So here's your solution. Get yourself an iron pan. Put the mass of junk in the pan. Build a camp fire around it. Let it burn hot.

The plastic will burn off, leaving you with your silver.

Any melt shop should be happy to do this for you, and pay you out 92-95% on the silver at that quantity. They might charge you a small incineration fee, but it will be manageable.


----------



## snoman701 (Aug 1, 2019)

stickle said:


> 44 lbs of 90% coin silver is almost 600 ounces of silver, almost $10,000. Not worth it? :shock:


Never said it wasn't worth it either...just said it's just junk silver. Meaning it's value is the intrinsic value of the silver, not it's numismatic value in rarity. Even having been through a fire, there are coins that would still carry value above ASV (actual or assayed silver value). 

Junk silver (silver that is immediately identifiable as silver, such as coins) isn't carrying a premium right now. 

You have a recovery lot. Don't spend too much time trying to recover it. If a big friggin hammer doesn't work to free the silver, then fire will. Hot oil and stuff is just an invitation to hurt yourself.


----------

