# Silver from Silver solder 40%



## Slochteren (May 13, 2015)

I have 1 kilo silver solder 40% Silver 5% cadmium and rest is lead and tin i assume. 
I just have to put it in 1/2 Liter Nitric(53%) and 1/2 water and wait till it is dissolved and cement out with Copper?
If i calculated right 1/2 liter Nitric(53%) dissolves +/- 400 gram silver.

Thx Paul


----------



## GotTheBug (May 13, 2015)

Not sure right off the top but I think the lead nitrate might be an issue.


----------



## patnor1011 (May 14, 2015)

Is it in a metal form or it is a paste?


----------



## Slochteren (May 14, 2015)

it is in metal form.

assuming what is int it won't bring me further, just did some checking and found a label on it. it is L-Ag40CD Ag:40,00 Zn:21,00 Cd:20,00 Cu:19,00 also no lead or tin. 
"I just have to put it in 1/2 Liter Nitric(53%) and 1/2 water and wait till it is dissolved and cement out the silver with Copper?" 

this will work?

Paul


----------



## kurtak (May 14, 2015)

Slochteren said:


> it is in metal form.
> 
> assuming what is int it won't bring me further, just did some checking and found a label on it. it is L-Ag40CD Ag:40,00 Zn:21,00 Cd:20,00 Cu:19,00 also no lead or tin.
> "I just have to put it in 1/2 Liter Nitric(53%) and 1/2 water and wait till it is dissolved and cement out the silver with Copper?"
> ...



Paul

No - 1/2 liter of 53% nitric will not be near enough to get the job done

It takes "about" 1ml of 70% nitric to dissolve 1 gram Ag - this depends somewhat on conditions such as closed reaction vessel - open reaction vessel - reaction vessel under vacuum & heat applied &/or how dilute - all of which will change the amount of nitric needed - so its a factor of more or less depending on conditions

Also - it takes "about" 3.5 - 4 ml of nitric (again based on 70%) to dissolve 1 gram "base metals" - again depending on conditions as well as type base metal (example - it takes more acid to dissolve the same amount iron then the same amount copper)

So there are to many factors to give you an exact --- I don't have the time right now to go into all the details &/or do the math (for your 53% --- I work with 68% which is close enough to 70% that I factor it as such & I also know my system/method so am able to come close to the acid I need when "starting" a reaction)

The point I am making - based on 1 ml 70% nitric (& 1 ml D-water) to dissolve 1 gram Ag & 3.5 - 4 ml 70% nitric to dissolve 1 gram base metal --- it would take "about" 2,500 ml of 70% nitric to dissolve 1000 grams of 40% Ag/60% base metals that are alloyed - factored as follows

400 grams Ag X 1 ml nitric (70%) per gram Ag = 400 ml nitric
600 grams base metal X 3.5 ml nitric (70%) per gram base metal = 2,100 ml nitric
400 ml + 2,100 ml = 2,500 ml (or 2.5 liter)

Now to show how that can change based on conditions (system/method) --- when I make my electrolyte for my silver cell (with pure Ag crystals from the silver cell) I can dissolve "about" 500 grams of silver with only "about" 400 ml 68% nitric --- so I actually use less acid (& a bit weaker acid) then what is considered the "rule of thumb" for dissolving silver - that's due to my system/method & lots of experience with the system/method I have in place

Kurt

Edit to change AG to Ag


----------



## Barren Realms 007 (May 14, 2015)

To dissolve 1g of silver it takes 1.13ml of nitric.


----------



## Slochteren (May 14, 2015)

Thanks for the info, i wasn't that wrong with my calculation only didn't count the basemetals to dissolve...

Will try a small amount first in AP to dissolve some base metals first.


----------



## Palladium (May 14, 2015)

You need nothing but nitric for this. ANY chlorides will mess this up and serves no purpose. The silver will chloride up and will passivate the surface.


----------



## Lou (May 14, 2015)

Given the Cd content, I'd say skip dissolving it and sell it to someone set up for it. 

At least no tin!


----------



## Slochteren (May 14, 2015)

Nobody want it because there is Cd in it, they say they have to clean there whole system after processing something with Cd in it. 
What i have read here about cadmium it is dangerous when melting it, i'm "only" dissolving it. Or are there other dangers?


----------



## Lou (May 14, 2015)

It's dangerous when in solution--as you dissolve it, mists of cadmium nitrate contaminate the work area.


----------



## nickvc (May 14, 2015)

Lou said:


> It's dangerous when in solution--as you dissolve it, mists of cadmium nitrate contaminate the work area.




Listen to Lou if he says it's bad it is!


----------



## goldsilverpro (May 14, 2015)

No tin or lead - good. Lots of cadmium - not good.

For 70% nitric, you would need a little less than 3 liters, at most (probably), to dissolve 1000g of that alloy. With 53%, it would take about 4.1 liters.


----------



## Slochteren (May 15, 2015)

I'm in doubt now what to do. 400 gr silver is +/- 200 euro. I can put the material in a buckte with 4,1 liter nitric and put somewhere in the field where it cannot polute a workspace and leave it there for a week. Without heat it will take some time i think. After it is dissolved will the Cd make any other trouble during cementing?


----------



## patnor1011 (May 15, 2015)

Do not do that. Murphys law says that somebody will find that bucket in a field. I would rather use system where you can control fumes somehow. Watch-glass over small glass beaker, all in a closed bucket, something like that. I would definitely do not attempt to work on whole amount rather on very small sample.
Then again, I would probably do not go ahead with any of this, you can safely store it and wait maybe you will find a way where to sell it in a future. 200 euro is not worth to endanger your or somebody else life. 200 euro is not going to make difference in your life, trying any of this may make your life miserable, that is not amount worth risking everything you got. 
Why not wait till silver gain much more value (that may happen in future), then you will find company wiling to buy or process it.


----------



## kurtak (May 15, 2015)

Barren Realms 007 said:


> To dissolve 1g of silver it takes 1.13ml of nitric.



Close but not quite right - the actual number is 1.17 ml 70% nitric to dissolve 1 gram pure silver - or at least that is what stihl88 (used to be an active member) had in his signature line :arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=17233&p=177273#p177273

However - that's not an absolute - how much metal 1 ml of nitric will dissolve does depend on the conditions the nitric is working under - which is way I said "about" 1 ml 70%

I process lots of silver & I use 68% nitric

I can dissolve more then one gram silver with less then 1 ml nitric (68%) & do so every time I make my electrolyte for my silver cell

When I make my electrolyte I use 500 grams silver crystals from the cell & I only need to use "about" 400 ml nitric (68%)

That's because I do it in a closed system (beaker with a watch glass on a hot plate) & extra D-water

4 liter beaker + 500 grams silver + 600 ml D-water + 400 ml nitric & I add "all" the nitric at once on the hot plate with the hot pate turned on at the #1 setting (its a stirrer hot plate) when the reaction takes off it foams up to about the 2500 - 3000 ml mark (depending on how fine or how dense the Ag crystals are) & the reason for using a 4 liter beaker

The reason way I ad "all" the nitric at once is so I don't need to remove the watch glass to ad more - this keeps most of the Nox fumes inside the beaker other then what escapes out at the pour spout --- what happens here is that because the Nox fumes are held in the beaker - and - because I use 400/600 ml (acid/H2O) instead of 50/50 the Nox fumes are absorbed back into the solution (like nitric is recovered by running the Nox through a H2O2 chamber of a scrubber) so you get more complete use of the nitric compared to doing the reaction in an open vessel &/or vacuuming the fumes off 

If the beaker does not have a good straight edge all the way around the top & there by not giving a good watch glass seal all the way around (there by allowing fumes to escape around the edges as well as at the spout) it won't quite dissolve all 500 grams Ag (leaving about 1/2 oz un-dissolved Ag) if there is a good watch glass seal I will have to add a bit more Ag to use up all the free nitric

The same principle works when dissolving raw metal (contact points, sterling, etc.) I do it in a SS pot with the lid on so no fumes escape (the lid is loose enough that there is no need to worry about pressure build up but tight enough to keep the fumes in --- doing this you will get "much" better use out of your nitric - meaning you will use less nitric then the "rule of thumb" ml nitric/gram metal ratio numbers

Kurt


----------



## Slochteren (May 15, 2015)

Thx Kurt for detailed post, i will process this solder wenn i have built my fumehood regarding the Cd. 

Paul


----------



## Anonymous (May 15, 2015)

Lou said:


> It's dangerous when in solution--as you dissolve it, mists of cadmium nitrate contaminate the work area.



Lou I was reading down the thread and wondering when someone was finally going to mention Cadmium and Cadmium Nitrate- - thanks for restoring my faith..... :shock: :shock: 

The topic of toxic substances in ewaste is something I even started a thread about but there was very little take up. I wish it was taken a bit more seriously, because if a number of experienced members don't even comment on the Cadmium that's really worrying. Sorry lads it's a pet "thing" of mine. 

I agree with the suggestions to pass it off to someone else to do.

Edit I quoted myself instead of editing this post, therefore I deleted my re-post.


----------



## kurtak (May 16, 2015)

spaceships said:


> The topic of toxic substances in ewaste is something I even started a thread about but there was very little take up. .



Jon

could you provide a link to that thread I am interested in reading it because I agree that sometimes not enough is said about the hazardous/toxic substances found in processing e-waste --- when I get really busy I sometimes miss thing that have been posted which must have been the case on what you posted

concerning cadmium I have posted quite a bit of info concerning its toxic hazard being as how most of the silver I process comes from processing contact points which always involves Cd due to the solder/braze

Concerning the Cd nitrate mist - if you keep a lid on the reaction vessel until the reaction is "complete" it should not be a big problem as it will (the lid) keep the mist inside the vessel --- the same goes for when cementing the copper & other base metals (Cd included) with iron - keep a lid on it when cementing

The other place of concern is when melting such as melting the cemented copper or de-soldering points from buss bars etc. --- this needs to be done so that the fumes are drawn or blown away from you & I always advise that you also wear a good cartage type respirator

The processing of contact points has been discussed many, many times here on the forum & contact points always involve Cd --- so I see no reason to advise against processing this material because of the Cd --- but rather advising that the Cd is a toxic hazard & therefore the need to take proper precautions --- as is true with most of what we do

Kurt


----------



## Anonymous (May 16, 2015)

With pleasure Kurt

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=47&t=21667&p=224305&hilit=cadmium#p224305

Regards

Jon


----------

