# Silver and Rust...



## kjt124 (Apr 7, 2013)

I did a dumb thing and I am hoping someone on the forum has a good idea on how to recover my mistake...

I was in the middle of recovering my silver filter papers (which I burned until nothing would burn, pulverized, threw the ash into a caustic solution in an effort to convert any chloride to oxide, and did a crude panning to get most of the black into filter paper and dirty silver left in the original jar) when I made a stupid mistake.

I put nitric and some peroxide into the original jar with the dirty silver (looked pretty clean to the eye) to digest and then follow up with cementation. Near the end of the digestion, to make sure I used the tail end of the nitric on the last little bit of silver before adding any i put the jar into my cast iron skillet on the burner... (no I haven't yet found any pyroceram).

No the jar is not a heatable vessel. Yes the jar broke neatly in a ring around the bottom. Yes, it spilled my silver nitrate (very low pH) into the iron pan that had been outside for a few days being used and had developed much surface rust. Begin laughing if you like.  

Anyway, I collected my liquid that now has a lot of rust in it and went from the nice familiar copper nitrate color to a very distinct nickel chloride looking green with a bunch of rust in the bottom. I can only imagine the green comes from the combination of the copper blue and the iron yellow. I don't believe there is any concern for other metals to be in this solution in any non-trivial amount other than silver, iron, and copper. There should be no other precious metals at all.

Does anyone have a good idea how to get my silver back out of a very dirty solution that is clearly loaded up with iron? It is a small quantity of liquid - on the order of 200 mL - but I would like to get it back if possible. I would be very unhappy even letting an ounce of silver slip away  I tried searching for something with iron and silver in it, but perhaps I am not keying in the right things. Any help would be appreciated.

Thanks guys,
Kevin


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## kkmonte (Apr 7, 2013)

kjt124 said:


> No the jar is not a heatable vessel. Yes the jar broke neatly in a ring around the bottom. Yes, it spilled my silver nitrate (very low pH) into the iron pan that had been outside for a few days being used and had developed much surface rust. Begin laughing if you like.
> 
> Thanks guys,
> Kevin



I don't think there will be many (if any) people laughing at this. Just another reminder that safety is of the utmost concern and luckily nothing serious happened.

Sorry I haven't started working with refining silver so I have no idea, but I bet Butcher knows how to get it back!

Ken


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## kjt124 (Apr 7, 2013)

Agreed - I should have said if all I lose out of this is an ounce of silver then I am lucky it was a silly mistake and not a costly one!


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## FrugalRefiner (Apr 7, 2013)

Kevin,

I think you can recover pretty easily. First, we have to assume that some of your silver already cemented out of solution from the iron. Any sediment in your solution might contain silver as well as any crusty residue in the skillet. I would clean the skillet out well with a minimum amount of distilled water, doing several small washes and scraping/scrubbing well to remove any loose material, saving all the wash water and sediment. I would add just enough nitric acid to this wash water/sediment mix to put the sediment into solution. Then cement the silver out with copper. You can treat your original solution the same way. If there is sediment, add a bit of nitric to dissolve it, then cement with copper.

Depending on how much iron is in your solutions, you may have a fair amount of drag down. If the cemented silver is really dirty, you can redissolve it and cement one more time to clean it up.

You really shouldn't lose much at all. The good thing is that you used a secondary containment container. You would have probably lost a lot more if you hadn't used that skillet.

Dave


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## kjt124 (Apr 8, 2013)

So the presence of the iron won't affect the copper cementation much at all except for drag down possibilities? So I guess all this mistakes cost me at this point (luckily) is some nitric and a bit of life span on my skillet. That is very good news!

Yes, I am very glad I had the secondary containment as well.

Thanks Dave, I'll give it a go a bit later this week.

Kevin


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## mikeinkaty (Apr 8, 2013)

kjt124 said:


> So the presence of the iron won't affect the copper cementation much at all except for drag down possibilities? So I guess all this mistakes cost me at this point (luckily) is some nitric and a bit of life span on my skillet. That is very good news!
> 
> Yes, I am very glad I had the secondary containment as well.
> 
> ...



Kevin, I use SS pans I purchased at the local Goodwill store. I use a pan big enough to catch what ever I'm heating should the glass vessel break. I use SS pans for heating water, drying cememt or crystals, burning filters or basically about everything needing heat. I do have a couple of Corning pyroceram pans but rarely use them. Mike


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## Anonymous (Apr 8, 2013)

You need to get a filter like the type I posted here, or something similar. Using these types of filters, you'll trap any solids that may slip through the filters. I have proof of that.

If you have an old copier/fax/printer machine laying around, take it apart and you'll find a filter that can be reused over and over again. That same filter will trap just about anything that isn't liquid inside, and (or) on top of it. I'll post later on about filtration methods that I have proof that works better than regular coffee filters, no matter how many of them you stack together.

Read the thread below. It works for silver too.
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=53&t=17743 

..........................................*DO NOT USE COFFEE FILTERS FOR THE PROCESS EXPLAINED BELOW.*


*1.* Decant your solution into container *no# 1*, with the filters I've mentioned above. The filter is your easiest and best way to make sure you're getting all of your silver. It traps all particles and lets your silver flow through the filter at the same time.

*2.* Spray the original container with distilled water and then dump that water into container *no#1*.

*3.* Take container *no# 1* and add copper to it. But, before you do so, depending on how much Nitric Acid you used, it's best to add more than double the volume with distilled water. 

*For example*, if you have 400 ml of solution, I, myself add enough distilled water to make the solution 1000 ml. even with 200 ml of nitric solution, add 800 ml of distilled water to the solution and drop in some copper. The silver will start to drop almost instantly.

*4. *The solids that do not drop through the filtration, put them into a beaker and add a small amount of nitric acid to it. If the silver cemented in any way before, it will redissolve. Take that and filtrate that through the same filter I mentioned before.

If you filter the way I mentioned, your solution should be as clear as water. If your solution has just a hint of grey to it (I know, you think it's silver), it's contaminated with other metals or debris. If you use the filter I'm talking about, you'll have silver, without any contaminants. 



Kevin


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## kjt124 (Apr 8, 2013)

mikeinkaty said:


> Kevin, I use SS pans I purchased at the local Goodwill store. I use a pan big enough to catch what ever I'm heating should the glass vessel break. I use SS pans for heating water, drying cememt or crystals, burning filters or basically about everything needing heat. I do have a couple of Corning pyroceram pans but rarely use them. Mike



That is a great idea mikeinkaty. I'll be hitting the garage sales shortly and imagine I can find a decent stainless pan pretty easily and cheap. Stainless probably transfers heat better than the pyroceram as well. I have a nice heavy gauge stainless bowl, but it leaves much to be desired as far as sitting on a burner.



testerman said:


> If you have an old copier/fax/printer machine laying around, take it apart and you'll find a filter that can be reused over and over again. That same filter will trap just about anything that isn't liquid inside, and (or) on top of it. I'll post later on about filtration methods that I have proof that works better than regular coffee filters, no matter how many of them you stack together.



I just so happen to have an older inkjet waiting to be torn apart - I guess I just got my motivation to do so. Do you ever run into any problems with trying to get your solids back out of the filter, testerman? This filter looks like it would be great for filtering gold precipitate before redissolving. I imagine you could throw the filter right into the solution to dissolve the gold. I'll look into the polypropylene felt as well, but I really hate to pay for things with a small scale operation. I'll be checking out this inkjet first. Hopefully the ink didn't get to the filter yet... I'll see what this silver turns out like and post a pic if it looks good 

By the way, I have the filter paper from before with silver oxide and ash (unknown proportions) in it (probably heavy on the oxide, but who knows right now - it is all black). Is there an oppinion on the best way to handle that? Direct melt with borax, shatter off the borax, redigest in nitric sound right? Should I get some soda ash finally and add that in the mix? Or should I skip the flux entirely and go straight to melt then redigest? Original material was ashed very well at the beginning of this operation, pulverized and ashed again - should be no organics whatsoever.

Thanks guys!!

Kevin


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## kjt124 (Apr 16, 2013)

Inkjet printer sponge came out disgusting, but surprisingly cleaned up really well. I used it as intended I, but believe it or not some rust still made it through. I had to re-filter 4 times. That is the last time I make the mistake of flooding an iron pan with an acid solution...

Anyway, I melted my AgO (which was not quite as incinerated as I thought it was...) with (to me) was a large amount of flux. It came out kind of gross, but I got metal out of it. I redigested it in nitric and dropped it with the other iron impregnated solution. Clearly I had a LOT more nitric than anticipated (or perhaps there is some effect from the iron) because the solution went to an incredibly saturated copper (nearly black when all was finished).

Rinsing and such was a bit arduous, but seemed to go well. This is clearly not clean silver at this point as I am sure there was plenty of entrainment. Even though I diluted the original solution, the final solution was dark to the point that a regular dollar store flashlight would barely shine through it.

Really at this point the only question I have (since I think it went rather well on my first filter paper processing considering the catastrphy in the middle of it all) is this: Would this silver be fine to save as inquart silver or is the threat of iron too problematic to ignore? I do not have a silver cell yet as my quantities simply don't warrant it yet. Since I have a better idea of silver amount now should I redigest the whole thing and drop more cleanly this time? I haven't weighed it as it is still drying, but it looks to me to be roughly 2 ounces at best.

Thanks guys,

Kevin.


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## Anonymous (Apr 16, 2013)

After the nitric bath, filtration is the key. 

You most likely didn't have enough or a tightly fitted filter in place, because if you did, you would only need to filter just once, and if you used nitric acid to redissolve your material, it would have been clear as water.

The filter I showed that I am using, I've used the same one 3 times now and every solution I filter, no matter the color, my solutions are 100% clear and nothing ever ever settles to the bottom of my jars.

You need to get a big enough piece and make it super tight and squeeze it in the top portion of the funnel. Don't put it in the bottom of the funnel, because, like I found out yesterday, some sediments are likely to get through... or I didn't have my filter tight enough. Once I reused my other funnel that I used before and I re filtered my solution, the solution was clear and I caught all the other sediment in that filter. If you filter properly, you'll remove mostly anything that doesn't belong there.

I would simply melt the silver as is, then reprocess it again in Nitric. This time, filter it good. You'll remove all the other stuff and you should have mostly pure silver.

For the most part, using the filters I use now, I only have to filter my solutions just once. It works for me.

Kevin


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## FrugalRefiner (Apr 16, 2013)

kjt124 said:


> Really at this point the only question I have (since I think it went rather well on my first filter paper processing considering the catastrphy in the middle of it all) is this: Would this silver be fine to save as inquart silver or is the threat of iron too problematic to ignore? I do not have a silver cell yet as my quantities simply don't warrant it yet. Since I have a better idea of silver amount now should I redigest the whole thing and drop more cleanly this time? I haven't weighed it as it is still drying, but it looks to me to be roughly 2 ounces at best.


Kevin,

Considering how contaminated your solution was when you cemented, I wouldn't recommend using it for inquartation yet. It's just not worth the risk of adding contaminants to your gold.

As you said, redigest in just enough nitric to get it back into solution, then cement once again. There's no need to melt in between. The cement silver will dissolve easier. Just be careful to avoid a boil over. Dissolving silver in nitric acid is exothermic. Because the cement is so fine, the reaction will be rapid, and as the solution gets hotter it will become even more rapid. Add all the water you expect to need to the cement. A little excess is fine. Then add the nitric just a little at a time. Stir and let it react completely before adding more. Have a spray bottle of distilled water handy just in case it starts to run away. Oh, and keep your reaction vessel in a secondary catch container, preferably not cast iron. :lol: 

Dave


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## butcher (Apr 17, 2013)

silver and iron will not mix in a melt.
gold and iron will amalgam together in a melt.

I would not melt silver contaminated with iron with the gold.

You could clean out as much iron from your silver as you can, then flux melt your silver, and collect iron in the slag, then your silver would be cleaned up enough to use with your gold.

Iron is one metal that can be hard to remove chemically, as it can in some circumstances form iron hydroxides which are acid resistant, in solution you can have both soluble and insoluble iron compounds, (sometimes this can be a good thing as gold can be leached from a red rouge iron powder, even with strong acids that dissolve gold this red iron hydroxide compound will not go into solution).

Strong heating of a soluble iron chloride solution can make an insoluble iron oxide-hydroxide powder.


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## kjt124 (Apr 17, 2013)

Very interesting. Once again, something I thought was rather simple turned out to have nuances...

Thanks Butcher, I completely forgot about the gold and iron thing. I don't feel like introducing that combo into my experience unless I have no other choice.

Would it be worth trying to force out some iron hydroxide before dropping my silver by raising the pH to about 9 and re-acidifying before precipitation (filtering in between, of course)? Or would the addition of NaOH make silver oxide before iron hydroxide? I am not particularly good with flux yet as I don't entirely understand the ins and outs of the various flux ingredients (unless you are just talking about mixing it up with some borax as the flux). The tiny melting dish I use works great an ounce at a time, but I have my doubts about scraping slag in it.

Testerman, I'll retry your filter idea. I wasn't very satisfied how it turned out, but I could have been accidentally lazy from the disappointment over the spill. No biggy. Are you just using it under a gravity filtration or are you adding vacuum? That is definitely a slow filter, but in this case probably worth the wait.

Thanks as always guys. You are very patient and generous.

Kevin


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## Anonymous (Apr 17, 2013)

kjt124 said:


> Testerman, I'll retry your filter idea. I wasn't very satisfied how it turned out, but I could have been accidentally lazy from the disappointment over the spill. No biggy. Are you just using it under a gravity filtration or are you adding vacuum? That is definitely a slow filter, but in this case probably worth the wait.
> 
> Thanks as always guys. You are very patient and generous.
> 
> Kevin


I am currently using regular funnels (various size funnels) which has a large drain spout. If you use a large funnel, you can pour more liquid in it. The filter should be no more than 1/2" deep, and it should be cut long enough and rolled up, so that if it doesn't fit in the funnel, you can always trim some off and re roll it until it's nice and snug in the top of the funnel.

It does take some time and it can be a slow process, but, if you decant (pour just liquid in first) it'll go faster and then add the powder/solids in afterwards. 

Kevin


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## kjt124 (Apr 17, 2013)

Patience is valuable in this hobby. I do have a nice big funnel and just recently got a hold of an old computer tower that holds it nicely (CD ROMs make nice risers for your receiving vessel ). I'll play around with it as I can see the obvious benefit of the chemical resistance of this filter media.

I'll let you know how it comes out. I am surprised at how easy they clean up!

Thanks
Kevin


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## Anonymous (Apr 17, 2013)

kjt124 said:


> Patience is valuable in this hobby.


I was going to say that to you, but I figured you would understand that that is what's definitely needed in doing this recovering/refining and especially working with the chemicals.

Glad you know it. I want to scale up myself and make filtering go faster, but for now, I find other things to do until it filters down to a certain point, then I add more to the filtration.... or... you can always have more than one filtration setup at a time. The Dollar Store sells the 3 pack filters (they're not that big though, but they get the job done). You can always check your hardware store, auto parts store and compare the different size funnels. From what I've been learning so far, you'll never have too many funnels. In other words, for every glass vessel you use, beakers and other glassware, you should have a funnel for each one at any given time... different sizes too.

Kevin


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## kjt124 (Apr 21, 2013)

Thanks testerman. I have a side eye out for additional funnels lately .

So I tried redigesting the dirty silver in a calculated batch of nitric this time. I got a black easily filtered sediment at the bottom that would not easily go into the nitric. I am assuming this to be iron hydroxide from butcher's description of its acid resistance. As I said it was easily filtered. However, upon cementation I got very dirty silver again...

I will try again on this thing with butcher's plan using a bit of flux and seeing if I can slag out a bit of this iron. I guess I got more in there than I thought I did. I suppose even if the slagging goes poorly I can always toss it in some nitric again and hit it with chlorides.

Does anyone know if the HCl (or salt) trick would successfully avoid precipitation of the iron? I believe iron chloride is soluble in water regardless of the valence, right? I would like to avoid chewing up so much nitric in a sort of iterative dissolving / cementation cleaning process. Maybe if it were an ounce of gold I would complain less .

Thanks guys,
Kevin


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## Geo (Apr 22, 2013)

you can make a small thum cell to run the high content silver in. i made one using an old medicine bottle and a cell phone charger. that should liberate the silver from the iron.


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## kjt124 (Apr 22, 2013)

An interesting idea... Haven't had much excuse to build a cell, but a little one like that where I don't care much about all the voltage and concentration specifics and where the anode slimes would be pretty easily discerned as trash might be a neat afternoon project. Not to mention I would have to melt the material anyway...

Off to have an adventure.

Thanks Geo.

Kevin


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