# Strange melting of cemented silver



## metatp (Oct 28, 2011)

Hi all. I have a strange contaminate (I think) in my silver anodes I just made. The melt temperature was a bit higher than normal. It also poured very easily and was very shiny. To see if it really had a higher melt temperature, I melted two different anode together. As I suspected, the "normal" one melted much faster than the suspect one. The cemented silver when melted also gave off a cool bright blue flame until it started melting.

the source is mainly sterling jewelry and flatware, but there were some silver contacts. When dissolved in nitric, there was not much left in the filter. I did incinerate before dissolving.

As idea about what the contaminate is? I will test the sample, but this is nothing I have ever seen before.

Thanks,
Tom


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## Oz (Oct 28, 2011)

Never directly melt silver contacts unless you are sure they do not have cadmium present. Many do and this is very toxic.


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## philddreamer (Oct 28, 2011)

Tom, did you cement with copper? If you did, maybe you have some Pd, which would cement along with silver, but melts @ a higher temp than silver. I had a similar problem & when I used the cell I had a black sludge. Some was gold, but also tested + for Pd. I still need to finish running thru AR the rest of the sludge.

Just a thought. 

Phil


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## metatp (Oct 28, 2011)

philddreamer said:


> Tom, did you cement with copper? If you did, maybe you have some Pd, which would cement along with silver, but melts @ a higher temp than silver. I had a similar problem & when I used the cell I had a black sludge. Some was gold, but also tested + for Pd. I still need to finish running thru AR the rest of the sludge.
> 
> Just a thought.
> 
> Phil


Phil, I just remembered that I did include all the sludge from previous cells that I place place in nitric acid and cemented with copper. I remember that that cement was a bit dark gray than normal. I forgot about it when i was melting the powder. I will let you know what I find.


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## philddreamer (Oct 28, 2011)

Out of curiosity, why did you add the sludge to your .99% pure cemented silver? 
Remember that the sludge is the contamination that the cell process separated, so the end product is .999 pure silver crystals. If you add sludge from the bag to the new anode, you won't have a .99% anode, so you're defeating the porpouse. Separate & save all the sludge so you can run it thru AR, thus recovering any gold & PGM's in it.
Keep us posted!

Phil


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## metatp (Oct 28, 2011)

philddreamer said:


> Out of curiosity, why did you add the sludge to your .99% pure cemented silver?


I would like to say oops, but that would not be true. What I usually do is take the sludge, rinse it from the cloth with DI water. I then then add nitric acid to the sludge to dissolve the residual silver. I then filter. I save what is in the filter, but I cement the silver from the silver nitrate with copper. I never had anything in the sludge but traces of gold. Didn't think I had any Pd in any of my batches. I still doubt I have any Pd, but you never know until you test. I think there was just something that was dragged down when I cemented with copper. The original solution was very dirty.


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## Geo (Oct 28, 2011)

Pd is added to silver jewelry so that the silver will retain its shine longer.silver develops a yellow hue over time due to oxidation so a small amount of Pd is added as an oxygen barrier.


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## metatp (Oct 29, 2011)

Well, I dissolved the 44g anode in 50/50 Nitric acid/water. Color was clear with a very very light blue tint. I tested with DMG and no Pd was detected. Tested with Stannous and no sign of gold either. The solution is very clear. Does fine silver melt at a higher temperature than silver with 1-2% copper?


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## philddreamer (Oct 29, 2011)

Next thing I would thick of is nickle, so a DMG testing would give a pink color. Did you expirienced that?

According to wiki fine silver melts @ 1,763.2 F; & I found that the melting point of sterling. (92.5% Ag + 7.5% Cu) is between 1,650F to 1,760. 
Argentium sterling replaces part of the % of Cu with Germanium & its melting point its a bit under the that of the Ag/Cu sterling.

While searching I found this information, it might help you, too:
http://www.madsci.org/posts/archives/2001-11/1005200805.Ch.r.html


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## metatp (Oct 29, 2011)

Phil,

Thanks. Nickel was my first thought, but I did not detect it with DMG. I did test my DMG, and it is working fine. If it is Nickel, I would have expected the redissolve to be a little more blue or green. Once I cement the silver again, I would see if the same phenomenon.

Tom


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## Harold_V (Oct 30, 2011)

metatp said:


> Phil,
> 
> Thanks. Nickel was my first thought, but I did not detect it with DMG.


The test requires that the sample be made basic by the addition of a drop (or more) of ammonium hydroxide. If you eliminated that step, you would get results only if you had palladium present. The display for nickel, when tested properly with DMG, is pink. 

Note, too, that whey you introduce a drop of ammonium hydroxide, the solution, assuming it contains nickel or copper, will turn a brilliant blue. 

Harold


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## metatp (Oct 30, 2011)

Harold_V said:


> The test requires that the sample be made basic by the addition of a drop (or more) of ammonium hydroxide. If you eliminated that step, you would get results only if you had palladium present. The display for nickel, when tested properly with DMG, is pink.
> 
> Note, too, that whey you introduce a drop of ammonium hydroxide, the solution, assuming it contains nickel or copper, will turn a brilliant blue.
> 
> Harold


When I tested for Nickel, I tested the solid metal. When I did this on other solids, the DMG turned very pink when nickel was present. That is also how I test my DMG (using coin made of nickel). I assume this would show presence of nickel. Was I wrong?


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## qst42know (Oct 30, 2011)

I have never heard of DMG for testing solid metals, only solutions. Testing solid metals may be an inconclusive test.


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## metatp (Oct 30, 2011)

qst42know said:


> I have never heard of DMG for testing solid metals, only solutions. Testing solid metals may be an inconclusive test.


I've never got it to work on solutions for nickel, but my solutions have always been acidic.


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## qst42know (Oct 30, 2011)

A drop or two of Ammonia is used to change a test drop of solution from acidic to basic.


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## Harold_V (Oct 31, 2011)

metatp said:


> Harold_V said:
> 
> 
> > The test requires that the sample be made basic by the addition of a drop (or more) of ammonium hydroxide. If you eliminated that step, you would get results only if you had palladium present. The display for nickel, when tested properly with DMG, is pink.
> ...


Heh! If you get a pink reaction on solid metal, hard to say you're wrong----although I confess, I never tried testing solid metals with DMG. 

You are wrong if you test an acidic solution, however. You won't get the pink reaction, even if there's a huge amount of nickel present if the solution is acidic. That's why I commented on the use of ammonium hydroxide. 

Harold


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## metatp (Oct 31, 2011)

Harold_V said:


> You are wrong if you test an acidic solution, however. You won't get the pink reaction, even if there's a huge amount of nickel present if the solution is acidic. That's why I commented on the use of ammonium hydroxide.


Thank Harold. That may be why I think I never have any nickel when I've tested. I will test again. My guess is that it will be positive for Nickel.


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## kadriver (Nov 1, 2011)

metatp:

I had a similar experience just the other night.

I cemented a batch of silver dishes and 925 jewelry.

The cemented silver was very thick and fine, it is usually course and granular. I could only describe it as pluff mud.

It was darker than usual and it was heavier than normal. after drying, It usually took 3 spoons full to make a 48g anode bar. But this batch only took 2 spoons to make 48g bar.

Then the bars turned out much different than i am used to seeing.

Usually my anode bars are bright and shiny, about the same appearance as my 999 fine bars.

But these anode bars were rough and bumpy looking.

You can see pictures of the bars in this post, on the second page of the post:

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=11842&start=20

I suspect that there is another metal present. Since Pd will disolve in nitric when alloyed with silver, I suspect it is in fact Pd.

I have some DMG coming and i will test as i still have some solution set aside for testing.

I did a preliminary test on the silver nitrate with stannous chloride and to my surprise, I got a reaction - it turned a brownish color.

This is all new to me. I have never delt with the other metals before.

I plan on making a new batch of stannous chloride (the SnCl I used was nearly 6 months old) and retesting. I will post the results in the post listed above in this text.

kadriver


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