# Base metals not realy dissolving



## Bluebloomer (Aug 30, 2014)

Hello all,

Yesterday I did my first batch with some silver jewelry. It was about 90 grams of material, and at first the reaction with nitric acid was vigorous. Just keps adding little volumes of HN03 until reaction stops.
So when I had no more reaction I tried to filter it, but that became a royal pain... 

Can't filter because the liquid becasue of the sludge that's forming in the filter. So I filtered as much as I could, and put the solids that remained in the filter, back in a new batch of nitric.

Somehow the nitric is not realy reacting with the grey / brow sludge that was left in the filter.

This could mean the nitric acid is not the 68% as labeled or there are materials in the sludge that HN03 can't process any further.
When I stir the nitric / sludge liquid it fumes, then after a few seconds, it stops until I stir again.

What could be going on here ? Poor nitric <68% or is the remaining sludge just insoluble ?


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## Bluebloomer (Aug 30, 2014)

The solution turned milky blue, close to cyan, and perhaps I found the culprit; an ancient possible Greek, coin, that gave a black sludge upon testing with pure nitric acid. It travelled by accident with the rest of the silver into the nitric solution. The solution is now milky in color, and I have already 3 large coffeefilters with a grey / white sludge after I dissolved the dried sludge into nitric acid again.
What ever the material is, it will not dissolve in nitric acid. (or the nitric acid is not nitric acid at all..) 

I am sure it was all silver I used, exept for the ancient coin. I thought it was silver and it was so worn out that it wouldn't have any value to sell. I was suppose to throw it out..

For the gold plated rings and necklessess the nitric acid worked fine, and they left me with only gold in the filter after washing. So what went wrong in this case ?


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## butcher (Aug 30, 2014)

Are you diluting the nitric acid with water? you want to dilute the 68% HNO3 with equal volumes of water before using it.
Is this nitric acid home made? or did you buy it?
Are you using water that may have chlorine in it?

Even more dilute nitric is not a problem to use, you could even use very dilute nitric with heating and would no have a problem.

I am not sure what all metals you are putting into solution, but if tin is involved you will have problems, filtering will be one of those problems.

Letting insoluble materials settle before trying to filtering the solution can help, so that insoluble are not clogging your filter material, (that is if tin is not the problem).

From your description of a milky substance it does sound like tin may be the culprit here.

It is Normally a good idea to test and separate your scrap material before preparing it, or putting it into solution. 
For example testing the silver and putting it into piles (by type of scrap, or from the test results) to process it separately, after separation give it an incineration and wash to remove oils and dirt.
Separating the material by type may help to keep something like a coin, necklace, or a solder repaired piece of scrap, or materials with tin involved out of the batch of the rest of the sterling silver you are working on, from messing up the whole batch because of one problem piece of scrap...


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## Bluebloomer (Aug 30, 2014)

Hi butcher, thanks for your reply.

Yes I did dillute the nitric acid with an equal amount of demineralized water at the first go. The nitric acid is 68% bought at an online store that only sells chemicals (why I can buy beats me, these are dangerous good, but no questions asked so far..)
I am guessing that the bottles demineralized water (€ 1,25) do not contain chlorine..

Ah tin.. yes my guess is that the old coin was fully made of tin, and I dropped it in with the rest..

The incineration will be implemented next time..

How should I deal with the tin, asuming the old coin was indeed pure tin.. ?

Right now I am done with the 10th filtering or so, it's a little less milky and every filter is coated with a grey / white slurry. Now I have 2 batches; one is clear blue, and is now cementing with 2 solid pieces of copper from an Intel cpu cooler, strapped together with tie-wraps.
'
The second batch is a little less mily butmight still contain tin, any thoughts on how to deal with that ? Or perhaps just try to cement it out, and then further refining in a silver-cell ? The silver from the second batch will contain tin...


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## butcher (Aug 30, 2014)

If you can filter out most of the tin, which will be hard to do, using a coarse filtering material for the first filtering and re-filtering through progressively finer filter material may help to remove a lot of the tin oxidized salts from solution.
Once the solution will flow freely through your filter material you should have most of the metastannic acid or tin out of the way...
Tin in solution will most likely try to cement copper from solution with your silver, while you try to cement your silver, so you may need to re-refine your silver a second time, to remove cemented copper powders from your cemented silver powders before melting it for your silver cell. That is if you do get copper metal cemented out of solution, and not just copper salts which can be pretty much washed out of your cemented silver 

Depending on your scrap I may save the filtered powders, and read up on how to recover values from the tin salts. the process will not be easy, and they may not contain much value. there are several good posts that will help you with that study.

Next time keeping tin out of solution, or out of the bulk of your scrap silver, testing and separating your scrap will help, incineration of the silver scrap will help with oils or other trash, but incineration will not help here to remove tin or put it in a better state to use with nitric acid.

Keeping tin out of solution is the best way to not have a problem like this to deal with.
Others here on the forum can help you more with what you are working with than I can, I have not had that much experience with dealing with tin in dissolved silver nitrate solution. 
I have always tried hard to keep tin out of my nitric acid, and keep tin out of my silver nitrate solution.


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## Smack (Aug 30, 2014)

Butcher, how about if he lets it settle then decant, add equal amount of water to mud, stir well let settle, decant, let the mud dry, incinerate and treat it with hot HCL? Anything undissolved by HCL would be silver.


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## butcher (Aug 30, 2014)

Letting what will settle before filtering is just common practice for me, I normally give a solution all of the time it needs to let anything that will settle before I siphon (decant) the solution to be filtered.

I am not sure how well the metastannic acid would settle or if it would at all.
I am more used to dealing with tin in chlorides (from electronic scrap), than I am with tin in nitric or nitrate solutions.

How about if he lets it settle then decant, add equal amount of water to mud, stir well let settle, decant, let the mud dry, incinerate and treat it with hot HCL? Anything un-dissolved by HCL would be silver.

If I understand the problem he is dealing with he has silver and some copper dissolved in solution with the pretty much insoluble metastannic acid, I am unsure if letting it settle, will settle out all of the oxidized tin, I would try and let it settle if it will before trying to filter tin out of the silver and copper nitrate solution, then cement the silver from solution with copper.

Smack as far as treating the insoluble powders for possible values (gold silver...) your suggestion would be what I would try, it is the best way to try and deal with the tin.


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## Smack (Aug 31, 2014)

I was thinking it was mostly tin that was giving him trouble.


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## Bluebloomer (Aug 31, 2014)

> settle then decant, add equal amount of water to mud, stir well let settle, decant, let the mud dry, incinerate and treat it with hot HCL? Anything undissolved by HCL would be silver.



Nice! After everything I read, I should of realized that myself.... but thank you for solution smack  I grabbed the filters with metastanic gunk from the trash and I will let it dry, to incinerate later.

As you suspected Butcher, no silver precipitant, only fine powder in the tin contaminated silver nitrate however the liquid turned from milky cyan to clear blue.. I have no idea how to siphon it out without getting acid where I do not want it..

The first batch with the clear blue silver nitrate is now a dark green almost black with a nice layer of silver precipitant. I will filter that, and try to preciptate one more time with clean copper.

The second batch with the metastanic acid, makes me want to invest in a vacuum filter.. I will try to siphon most fluid out without disturbing the salts on the bottom, then filter, dry, incinerate and treat it with hot HCL.

Thank you so much for the information so far, it realy helps me out here. I guess I was so into the moment of making my first batch that I forgot all the rules and basic knowledge.
I will try to make pictures and post them here so you can get an idea of what I have now.
You guys saved the day because I was about to throw the filters out, and dispose the mily like fluid as lost....


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## Bluebloomer (Aug 31, 2014)

Smack said:


> I was thinking it was mostly tin that was giving him trouble.



Yes it was, about half the tin coin (asuming the coin was tin) dissolved in the nitric acid, but luckily I divided the liquid in 2 batches; one clear, one milky.

However, does something change now the milky cyan fluid has turned clear blue or is that just because the tin settled on the bottom and copper partially dissolved turning it blue ?

I also found out that one bracelet was Tibetan silver, that might contain lead and might only hold about 2% silver..

But first I will finish the first "good" batch, since this also might contain traces of tin (although not visibly in the fluid) I will re-refine it later when dried.

The second batch, is a bitch because I have to figure out a way to siphon the fluid leaving all particles on the bottom..


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## butcher (Aug 31, 2014)

There usually can be a few different ways to deal with problems.

I would try to avoid making silver chloride if I did not have to, but another way would be to evaporate the solution to salts, heat the salts to drive off nitrates as gases, then incinerate, wash with hot boil in HCl taking up with hot water , but letting the fluffy silver chloride settle well before decanting.... 

There are several ways to decant or siphon a solution.
Decanting pouring off the solution carefully trying not to pour or disturb settled powders.

Using a small hose to actually siphon the solution.

Several different ways can be used to start the siphon, you can fill the hose with water holding one end closed, insert the other into solution, hang the closed end over the jar leading to the jar below and remove the closed end.
A suction tool like a wash bottle, syringe, suction bulb or other suction tool can be used to start the siphoning...

what I like is a syringe type suction bulb, and a plastic pipette to actually suck out liquids without disturbing powders
http://goldrefiningforum.com/phpBB3/search.php?keywords=suction+bulb&terms=all&author=butcher&sv=0&sc=1&sf=all&sk=t&sd=d&sr=posts&st=0&ch=300&t=0&submit=Search


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## Bluebloomer (Aug 31, 2014)

I found a 100 ML syringe, and I took the fluid out that way, filtered the remaining solids and I repeated this process 3 times this morning (got out of bed at 5 in the morning here, some 5 hours ago) 

The "good" silver has been washed 7 times now, 1 time with dilluted HCL the rest with boiling hot demineralized water as distilled water costs too many in this expensive country.
Does anybody see a problem using demineralized water instead of distilled water ?

Now I'm left with 2 litres of blue liquid, that holds nothing anymore right? Tried dropping some HCL in a small amount of fluid but it only turned the fluid more blue, no precipent. So I can discart it.. ?

Luckily it wasn't that much silver, and it wasn't high quality either, so it could be worse...

There is a good amount of silver chloride in the filter to dry now, and perhaps an equal amount of sludge with stannic acid in the filters also to dry. 
So, thank you all for the information and help so far. For a first timer refining silver and making such a big mistake with the tin coin it's not all that bad afterall.. I was afraid it would turn out to be a giant clusterf..

- I can discard the remaining fluids now ? It's just too much to try and evoporate it, there seems to be no more solids in it.
- Filters with the remaining silver and tin will be dried, incinerated, treated in HCL dried again and then redo the nitric process ?


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## the iron dwarf (Aug 31, 2014)

do not just pour the waste down the drain!
you have 2 choices
either read up on treating waste on this forum or get a company that deals with chemical waste to take it

you need to make sure all metals are removed and then neutralize the acid BEFORE you can dispose of it


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## Bluebloomer (Aug 31, 2014)

No way I was intending to pour it down the drain !

Just couldn't find a topic regarding waste, and how to properly deal with it..


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## maynman1751 (Aug 31, 2014)

> There is a good amount of silver chloride in the filter to dry now



DO NOT dry the silver chloride!!!! Keep it wet until you are ready to convert it to elemental silver.


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## butcher (Aug 31, 2014)

I may be getting lost on what is going on.
I would not have use HCl on the silver cemented with copper, as I would try to avoid silver chloride.

Stannous chloride with silver chloride can reduce the silver to form silver metal powder and a stannic salt of tin.
SnCl2 + AgCl2--> SnCl4 + Ag(s)
although you will most likely still have silver chloride mixed in these powders.

Stannous chloride SnCl2 can also reduce copper II chloride CuCl2 in solution to copper I chloride CuCl (a white powder).
CuCl2 + SnCl2 --> SnCl4 + CuCl

The CuCl powder with HCl acid can give us the soluble CuCl2 (blue, green or brown depending on concentration)
2CuCl + 2HCl --> 2CuCl2 + H2(g)

If your using HCl washes, I see no reason to worry about a little tap water with chlorine as a disinfectant involved.

You can do most of the process in the Corning Pyro Ceram dish on your hot plate, you can use a hand held propane torch to incinerate the powders, and then do the acid washes (just about everything except filtering or settling) in the same dish...

If you incinerate the powders you filtered out, I would crush them, and keep them crushed during the roasting process, stir them to expose them well to the air while they glow red hot, let cool.
Then give them a good boil them in HCl, copper oxide and most of the tin will dissolve in the hot HCl, any silver powders will form silver chloride, tin will somewhat go into solution as stannous chloride, if lead is involved it will also make an insoluble white powder.
While giving the HCl a boil, I would keep the powders stirring. to keep powders from burning onto your corning dish and giving them good exposure to fresh acid. 
Lower heat so you can let the insoluble settle, but I keep solution as hot as possible, (the hot solution will hold more dissolved metals, and some metals like lead are more soluble.
If the solution is strongly colored (normally from copper, as other metals like lead or tin do not color solution), you may have to repeat the HCl wash.

If you want to see if your picking up tin, a small test sample of the HCl wash can be diluted with a larger sample of water, the tin will hydrolyze in the cooled water and will look somewhat milky you can try and see how this small sample will go through a filter tin will not flow through the filter paper worth a darn.
stannous chloride is clear and gives no color to the solution, (copper or other metals can give solution some color), when diluted the stannous SnCl2 hydrolyzes to give insoluble Sn(OH)Cl + HCl
SnCl2 + H2O --> Sn(OH)Cl + HCl
You can also add a little NaOH solution and watch the reaction, to see if the insoluble tin oxide forms,
SnCl2 + 2NaOH --> SnO-H2O(s) + 2NaCl
Not too much NaOH as tin is an amphoteric metal and will dissolve again in excess alkali or base solution,
SnO-H2O(s) + NaOH --> NaSn(OH)3 (aq) dissolved back into solution (amphoteric)
There are several other forms of tin that are insoluble that you can make, or to determine if tin is in solution, tin is a complicated metal with a very complex chemistry, I think I could spend my whole life just studying this one metal alone. 



After decanting the HCl wash from the settled powders, you can remove lead with the boiling hot water washes, add water to the powders bring it up to a boil, and lower heat, giving the fluffy silver chloride time to settle with the solution hot as possible, the silver chloride will be fluffy and slow to settle, in your boiling hot water washes you can remove the lead, by lowering heat but keeping solution hot giving time for the silver to settle (its a bit slow), as you rinse, decant these water washes into a jar to cool, the lead will precipitate as lead chloride white crystals when this water is cooled, this same water can be decanted and reused on another wash to save waste volume of the water that is contaminated and added to your waste stream, while this jar is cooling, I normally add more water to the powders and repeat the boiling hot water wash, so I have two cooling jars, and if there is a lot of lead or powders to wash I reuse the water after it cools from the fist cooling jar, to repeat the process until no more lead is removed...

You may get a tiny bit of silver chloride mixed in with your lead chloride it can be separated later, by re-crystalizing your lead salts (I save my lead powders recovered in a jar to convert it to other forms of lead, like litharge to use in other processes later).

Ok now we have wet silver chloride powders (probably still with some other metal contaminants). (as suggested keep them wet, drying them out make it harder to deal with), we have a few choices of what we can do with them, we can convert them to silver metal with one of the different conversion processes, NaOH/Karo syrup, Iron metal, dilute 10% H2SO4. or HCl/aluminum.

But if you do plan on incinerating the silver chloride powders you will need to convert the silver chloride to another form of silver metal, or at least silver oxide first, as silver chloride is volatile at the roasting temperature, and your silver will go up in the white smoke in the process, this can be done with one of the silver conversion methods above, before the incineration...

Also note if there is any gold involved any time you have a nitric or salt of nitrates, HCl or chloride salt together with gold you will dissolve the gold or at least some of it, incineration can be used to drive off the previous acid or salt as gases before switching acids...

I could type about this discussion all day, but I do need to get back to work, studying the forum you will learn million times more than I could type in a few pages.

Dealing with waste, and safety, is something that anyone who plans on using acids and metals, or doing any chemistry with metals, should learn first, even before they open their first bottle of acid or base solution.

See Dealing with waste in the safety section, (also another good thread is something like the gorilla or elephant in the room), 4metals has made a great post on the subject, you will also find many other discussions throughout the forum on this subject that will help with that very important study.


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## resabed01 (Aug 31, 2014)

butcher said:


> I could type about this discussion all day, but I do need to get back to work, studying the forum you will learn million times more than I could type in a few pages.



That's not true Butcher, your posts are always full to the brim with information


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## Bluebloomer (Sep 1, 2014)

Butcher, thanks again for the informative post. I speak English pretty wel, but realy understanding it is a little more difficult. So I will read and read again so I can figure out what I am misunderstanding here.

Silver chloride should me converted to metalic silver with sodium hydroxide and detrose, is that the reason I should't dry it ?

I know it is photo sensitive, and I know it will deteriorate turning to salt, but the idea was to just smelt the silver chloride and then refine it with a silver cell.
But this is a bad idea?


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## butcher (Sep 1, 2014)

Silver chloride is volatile, roasting or melting most of your silver will go up in the smoke, silver chloride needs to be converted to silver metal, or at least a silver oxide, before melting.

Soda ash (sodium carbonate Na2CO3) can be used as a flux to convert the silver chloride in the heating fusion portion (of the melt)before actually melting, if done properly...

Silver chloride salts dry hard and bind up the crystals making them harder to deal with or convert to silver before melting.
Basically you need to do more study on silver chloride to get a better understanding of it and how to deal with it.


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## Bluebloomer (Sep 3, 2014)

I realy underestimated the intire process.. I watched hours and hours of youtube vids, and in some videos they dry the silver chloride then smelt it, and refine it in a silver cell.
But after the warnings here I started googling again and indeed drying silver chlroride is not the way to go. I guess I just saw a solution that I wanted to try but didn't read up on it.

Added some tabwater to the chloride and put it in a dark place, untill I can proceed with the process.

From what I understand the next step would be to use a heat resisent container, and add NaOH pellets untill it turns nearly black, then add some sugar syrup untill the reaction stops, is that right ?

What makes me doubt so much and what made me chose to dry the silver chloride is that I read so many different things about it, some say to use table salt, others say Soda, and others say Lye. Some use a syrup (we do not have Karo syrup so perhaps regular pancake syrup will do ?) others use dextrose sugar or crushed up dextrose tablets.

My guess is that NaOH will give the most violent reaction with a lot of heat, and the fine dextrose sugar can be made into a syrup by boiling it down a bit.

What is the difference in using NAOH, tablesalt and Soda ? Is it mainly the exothermic reaction?


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## butcher (Sep 3, 2014)

Bluebloomer,
Study first to prevent more problems.
There are several methods you can use to convert the silver chloride to metal.

If you choose on using the NaOH/Karo syrup (pure corn syrup), you can use another type of dextrose sugar in the reaction. 

Lye or caustic soda is just another name for NaOH sodium hydroxide.

Soda ash is sodium carbonate Na2CO3 or also called washing soda (used as a flux).

Table salt NaCl sodium chloride will be a byproduct of some of the reactions.

You will need to powder your cake of silver chloride which ever method you choose to use.

The most important thing is to study and understand the processes before you try them...

You tube and the intranet will be harder to learn from than the forum, studying the forum will help you understand much of the misinformation you will see in YouTube videos.


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## Bluebloomer (Sep 3, 2014)

I realy choked on the misinformation, plus the fact I did not study enough, obviously..

Sometimes I think I understand something,but then I realize that the English language is sometimes harder to understand that I would want to..
Still have to google certain words, or don't always understand the contex..

Since I read so many positive comments about LazerSteve's DVD's, perhaps I should just invest in those..

Thank you so much for all your patience and taking the time to go into detail about some of the steps and processes..


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## maynman1751 (Sep 3, 2014)

Don't feel bad. We all stumble and sometimes fall at first. Just take your time and follow Butchers directions and you'll be fine.


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## butcher (Sep 3, 2014)

GSP has made some amazing posts on the subject of silver and silver chloride, He also sells a book that is very helpful, It is well worth the little money he asks for it, you will also find many posts on this subject, from Harold, Lou, Juan Manuel Arcos Frank, as well as others, they have given us a lot of information on dealing with silver and silver chloride, you may try some searches of this subject with their names as the author, and you may find that treasure your looking for.


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## Bluebloomer (Sep 4, 2014)

Dispite all the mistakes (and a black AgCl smeer on my nose) you guys have educated me quite a bit.

I know now what NOT to do, and WHY not to do it that way anymore.

Also read some more posts from the people you mentioned before and sometimes it means reading it twice of more to understand it better, but there is allways the forum to ask about the details I might not fully understand. 

For now it's time to read, read and read more and stop improvising...

So again thank you all, you have been a great help so far.. !

Groetjes uit Nederland,
Bluebloomer


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