# questions about silver refining



## Lenkosh (Dec 16, 2012)

*I am new user in this forum so hello everybody !*
i have a few questions about silver reclaiming from silver nitrate solution, i have about 85 grams of mixed ingot that i have made from silver and gold saw dust , (i know that the main content of it is sterling silver and some 18k and 14k yellow gold), i then made shots from the ingot by pouring the melted alloy into bawl of water,I then boil carefully those shots of alloy in a mixture of about 110ml of 70% Nitric acid and 110ml distilled water until the shot completely digested by the acid, I left with some black ground coffee like dust in the bottom of the vessel. i wash that black "dust" well with distilled water, dried it well and weighted the result, i have ended with 12 grams of dried dust, i then put it again in the vessel with about 50 ml of diluted Nitric acid (in the same percentage as above +-) boil it carefully and watched for little to no reaction at all, washed it again the same as above, i have ended with 11.8 grams of dried "coffee grounds" which i have melted to a nice ingot of about 22-23 karat (by its color), it is malleable and i happy with the final results of my refining process which i have learned in the last 5 days mainly from reading this forum and watching youtube videos  ............

OK, so now i have that clear beautiful bluish "witch potion" and i have used the "copper wire method" to collect the silver crystals from it, i collected as much as crystals the liquid me to and after i see no crystals forming on the wire i have filtered the liquid again and tried the "table salt method" on it (NaCl), i definitely saw a reaction and a "cottage cheese" like precipitation forming on the bottom of the vessel, it is silver chloride i believe. i stopped at that stage and will be happy to get some help and advices, my main questions are :

*1. I learned that to produce "meltable silver" i need to convert the silver chloride into silver oxide, i have Sodium hydroxide to do it, but i don't know if to add it to the liquid or wash the silver chloride crystals first, dry them and then add the Sodium hydroxide ?

2. after i have the silver oxide, can i melt it as is, assuming that i don't need further purification ?

3. is there a benefit except of further purification doing another stage (with the sugar syrup) and getting it to silver metal particles before melting it ?*

Thank you in advanced (and sorry for that English).


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## philddreamer (Dec 16, 2012)

Here's some information that might help you.
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=37&t=14618#p146937
Phil


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## maynman1751 (Dec 16, 2012)

Your first mistake was adding NaCl to your cemented silver. The silver was already 99% pure. After rinsing it well and drying you could have melted the silver cement as is. There was no need to turn it into silver chloride. 
Seeing as you did, you should add the sodium hydroxide and Karo syrup to finish changing the silver oxide to elemental silver. Anymore ????'s, ask.
Good advice in topic Phil posted above.


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## kadriver (Dec 17, 2012)

Lenkosh said:


> i have ended with 11.8 grams of dried "coffee grounds" which i have melted to a nice ingot of about 22-23 karat (by its color), it is malleable and i happy with the final results of my refining process which i have learned in the last 5 days mainly from reading this forum and watching youtube videos



If you alloyed the gold and silver together, and the gold content was lower than 6k after alloying, then your gold "coffee grounds" could be as high as 99.8% pure gold if you made sure and washed all the dissolved copper from the gold powder.

This is a good first post - you produced some metal and shared your process - well done and thank you.

kadriver


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## Lenkosh (Dec 17, 2012)

maynman1751 said:


> Your first mistake was adding NaCl to your cemented silver. The silver was already 99% pure. After rinsing it well and drying you could have melted the silver cement as is. There was no need to turn it into silver chloride.
> Seeing as you did, you should add the sodium hydroxide and Karo syrup to finish changing the silver oxide to elemental silver. Anymore ????'s, ask.
> Good advice in topic Phil posted above.



I'm sorry for the misunderstanding but my *first stage* was to reclaim the pure silver with a copper pipe to produce silver cement (works better for me than a copper sheet or spiral), today i have dried and melted the final product and got me some nice 54g of pure silver (at least that whats its color tells..).
remember that this is my first time in refining.... 
only from curiosity and my fascination from the interesting process, i decided to add the NaCl to see if there are remains of silver and now i have some residue on the bottom of the vessel that appears to be silver chloride (AgCI), *so my question is what to do now ?*

*should i add the NaOH now to my diluted nitric acid with the AgCI residue in it, to convert it to silver oxide ?
OR, should i first wash it from the nitric acid and then add the NaOH ?*

Thank you.


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## Lenkosh (Dec 17, 2012)

kadriver said:


> If you alloyed the gold and silver together, and the gold content was lower than 6k after alloying, then your gold "coffee grounds" could be as high as 99.8% pure gold if you made sure and washed all the dissolved copper from the gold powder.
> 
> This is a good first post - you produced some metal and shared your process - well done and thank you.
> 
> kadriver



Thank you kadriver.

it was surely less then 6k gold, i think that's the reason why the remains where so tiny in size, the remains washed well with distilled water few times, dried well and then easily melted in a hot crucible with a little fluxing, as i say the melted powder produce a nice ingot that looks at least 23k in color, I'm a goldsmith for about 20 years, so i can tell that this is a very good looking gold, i will treat it as 23k and alloy it to 18k, because that's my preferred working material, soon I'll add some pictures of my new silver and gold ingots, thanks again.


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## g_axelsson (Dec 17, 2012)

Lenkosh said:


> I'm sorry for the misunderstanding but my *first stage* was to reclaim the pure silver with a copper pipe to produce silver cement (works better for me than a copper sheet or spiral), today i have dried and melted the final product and got me some nice 54g of pure silver (at least that whats its color tells..).
> remember that this is my first time in refining....
> only from curiosity and my fascination from the interesting process, i decided to add the NaCl to see if there are remains of silver and now i have some residue on the bottom of the vessel that appears to be silver chloride (AgCI), *so my question is what to do now ?*
> 
> ...


I thought it was quite clear what you described the first time, maybe only because that is what I usually do. At least this is how I do it....

- Dissolve silver (from whatever source I have for the moment) in HNO3 (nitric acid).
- I'm trying to use up the acid so I don't have to deal with excess acid. I have some scrap silver that I'm refining that I add the solution to at the end, it usually picks up some more silver until the acid is used up.
- Filter the solution, the filter goes into my burn pile. Gold plate on the silver ends up here unless it's enough to process separately.
- Cement with a copper bar, thick (4mm) copper wire or copper plate. Never use it up to the point that it starts to drop pieces of copper with the silver. At this stage any remaining HNO3 will be used upp by redissolving the cemented silver until exhausted.
When cementation is stopped I pour off the remaining solution into a jar with salt water (NaCl). Any silver nitrate left in the solution now falls as a thin layer of silver chloride (AgCl). I collect it in this jar until I have enough to process.
- I do the same thing with the water from the following washes of the cemented silver.
- The cemented silver goes to drying and melting if it is enough, or just storing as a powder.
- In the silver chloride jar I wait for the white precipitate to settled, If it starts to get filled up by liquid in the jar then I pour off the top part for waste treatment of the copper solution, leaving the silver chloride at the bottom. I add fresh NaCl and water whenever I empty the copper solution. Never letting the AgCl dry out.
- When I think I have collected enough AgCl then I treat it with lye (NaOH) and then sugar to get pure silver.

In practice I have noted that I usually ends up with a lot of crap with the AgCl, for me it is not a refining process, I use it as a recovery. So my next step is dissolving in HNO3 and cementing again, making a closed circuit. Silver scrap (film, keyboard mylars, contact points, silver braze from chips, jewelry...) goes in and out comes cemented silver, copper + other metals in solution and solids in the filter.
Sometimes when I have too little silver in a solution then I can pour it directly to the jar with silver chloride, via filtration of course. It's a quick way to extract the silver from a dirty solution.

Just save and process when you have enough.

As to your question, in principle, you should remove base metals whenever you can because clean solutions is always easier to handle than dirty ones. Wash the AgCl before doing the next step.

/Göran


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## butcher (Dec 18, 2012)

/Göran, 
Very good post, thank you.

I just want to make the point a little more clear for our new members, to decant the nitrate solution from the cemented silver before adding chlorides to the nitrate solution, to recover the remaining silver as silver chloride from the solution.

This way you do not have silver chloride (which will need conversion before melting) mixed with the cemented silver metal, which can be melted after washing well.


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## g_axelsson (Dec 18, 2012)

Thanks Butcher,

I see that it might not be fully clear, I could describe it like this too. In principle I have three jars.

1. A jar (or two) for dissolving silver, the solution is decanted and filtered into jar number 2. I'm aiming for an excess of silver scrap so the nitric acid is used up.
Even if I have silver with copper scrap and get some cementing it doesn't matter, I pick it up on the next batch.

2. A jar for cementing. I do the cementing, cleaning of the silver cement and final drying in the same vessel. After cementing is finished I pour the liquid into jar number 3. I do that with the water from the washings too. I don't use a filter, any free flowing silver particles will just mix with the silver chloride.

3. A jar for holding the silver chloride. I do the conversion into silver chloride and when I have enough I also do cleaning of the silver chloride and conversion into silver in the same vessel. The After settling of the silver chloride I decant the liquid off and it enters my waste stream for copper bearing liquids. The resulting silver is washed into jar number 1 and the cycle is completed.

This is almost a continuous system as I almost always have some materials in jar 1 and 3. Any excess nitric from for example inquartation or cleaning of gold goes into jar 1 to do some work, used nitric acid becomes an asset, not a waste problem for me. I have a couple of kilos with contact points that I'm slowly adding to the first jar when it starts to run out of silver.

This system works good for me as I don't do any external refining jobs, I'm only refining for my self and any silver held up in the jars is eventually coming out as cemented silver.
Any gold plate is either washed and added to a gold batch or caught in a filter and added to the burn pile together with undissolved PGM:s (Platinum Group Metals). Dissolved palladium or platinum is cemented with the silver and recovered with the anode slime in the silver cell.

/Göran


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## butcher (Dec 18, 2012)

/Göran,
I do a lot of my recovery similar, but what I do sometimes is hard to describe, so many times I do not even try to describe it.

You have done a very good job in your description.


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## kadriver (Dec 18, 2012)

Lenkosh said:


> i decided to add the NaCl to see if there are remains of silver and now i have some residue on the bottom of the vessel that appears to be silver chloride (AgCI), *so my question is what to do now ?*
> 
> *should i add the NaOH now to my diluted nitric acid with the AgCI residue in it, to convert it to silver oxide ?
> OR, should i first wash it from the nitric acid and then add the NaOH ?*
> ...



Lenkosh:

The silver chloride can be converted right now or you can save it up. I like to save mine until I have about a liter by volume before processing with sodium hydroxide and table sugar.

Before you convert the silver chloride, make sure and wash it with plenty of hot water - boiling if possible (tap water is ok, but it does contain particulate that will contaminate your silver chloride). It will settle very quickly at first.

I rinse it over and over until there is no more blue color visible.

Once it starts to get clean, you will find that the chloride won't settle as easily, some of it stays suspended.

I have a couple of clean 5 gallon buckets and I pour off the suspended stuff into these (if i am in a hurry) and process it later.

If I am not in a hurry, then I just wait for the suspended silver chloride to settle - sometimes it takes a while - even overnight between washings.

Once all the blue color is gone (that you can detect with your eye) then you can start testing the wash water with ammonia to detect dissolved copper that is not visible.

To test, get two small beakers or test tubes. Fill one (beaker A) half way with clean fresh water. Fill the other (beaker B) half way with some wash water off the top of your setteled silver chloride.

Now add 5 or 6 drops of 10% ammonia from the hardware store (or 29% if you have it) to the beaker with the wash water (beaker B).

Now set both these beakers right next to each other on a clean dry white paper towel and look to see if there is a color difference.

The test is very sensitive and the ammonia will reveal minute traces of copper by turning the wash water (beaker B) a faint blue color. Use the fresh water (beaker A) as a comparrison.

If there is still dissolved copper present then continue to wash with the hot fresh water and repeat the ammonia test as often as needed until no more color change.

By the way, goldsilverpro was the member who introduced me to this testing procedure. 

When the wash water is free of dissolved copper, as indicated with the ammonia testing, then you can begin the first stage of the conversion - adding sodium hydroxide to turn the silver chloride black.

First, cover the clean silver chloride with an equal volume of water. If you have 200ml by volume of silver chloride, then add fresh cold water to the 400ml level.

Then start adding the sodium hydroxide and stirring. The chloride will first turn grey, then to black as the reaction progresses.

I have used 4 lbs of sodium hydroxide to convert 2.2 liter (by volume) of silver chloride. But I do not know what the exact amount is that is needed to fully convert the silver chloride.

What I do is begin adding the sodium hydroxide and stirring until the chloride turns nearly black.

Then I draw up a small sample of the black in a small 100ml beaker. I add a few crystals of sodium hydroxide to this sample, pouring it down the side of the beaker so I can see if there is a reaction.

If I see the crystals turning the dark material even darker as the sodium hydroxide comes in contact with it, then I conclude that I need to add more sodium hydroxide to the whole batch.

If the NaOH does not produce a darker color, then I know that the reaction is complete as far as I will be able to take it.

Stirring is so important here. I have used powder tools to stir the chloride and it still will not get 100% converted. Some of the chloride will get bound up into clumps and the NaOH can not get to it.

I have made a stir rod from 3/8 inch PVC with 3 model airplane propellers attached to one end, place the other end in an electric drill and try to "cut" all the silver chloride clumps. But I have not used this device yet so I can't post any results.

Once you've got all the chloride converted, you can add the sugar or corn syrup.

But be careful here. If you add the sugar too quickly, the reaction will run away and erupt like a valcano!

If you are doing a large batch, then place the container with the silver inside another larger container to catch any overflow to prevent loss of your metal.

Even if you do it slowly, the reaction can somehow accumulate and vigorously erupt without warning.

Make sure and stir while you add the sugar (or corn syrup) and then sit back and watch the black granular looking silver material turn into nearly pure silver metal.

It really is amazing to watch it happen so quickly right in front of your eyes.

Once all the metal is converted, you must wash all the NaOH and sugar from the silver.

I use hot tap water and rinse the silver over and over until I get a neutral pH test using pH test strips.

The silver does not wash very easy and some silver will stay suspended - again calling for use of the 5 gallon buckets to pour off the wash liquid (to catch any suspended silver for recovery later).

If you don't get all the NaOH out, then you may damage the vessel you use to dry the silver. I ruined a nice large corningware casserole dish by not checking with pH test strips. The NaOH etched the corningware dish.

NaOH can dissolve glass!

once the silver is clean of sugar and NaOH, you can put it on low heat, dry, then melt into buttons or bars for your electrolytic silver cell.

Hope this helps you!

kadriver


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## Lenkosh (Dec 20, 2012)

Thank you everybody for your help and for sharing your experiences, thank you so much *kadriver* for the detailed, step by step process information.


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## maynman1751 (Dec 20, 2012)

I apparently misunderstood what you had stated. I thought that you had added the NaCl to the cemented silver. My mistake. It's all straight now. Just trying to help.


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## g_axelsson (Dec 20, 2012)

butcher said:


> /Göran,
> I do a lot of my recovery similar, but what I do sometimes is hard to describe, so many times I do not even try to describe it.
> 
> You have done a very good job in your description.


Thanks, coming from you it feels good.

8) 

Göran


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