# What other PM's drop with silver?



## mikeinkaty (Feb 18, 2013)

The reason I ask is that I just dropped 25 ozt of silver with copper (all in one bucket). After the clean-out I put more copper in the spent solution and set it aside for a couple of days. The first 25 oz made light grey very fine particle and heavy mud that turned into nice looking 990 bars. The dried mud was real pretty light grey in color. Then I recovered about 3 oz of cement from the spent solution bucket I had set aside earlier. It was light grey curdey looking stuff - not a mud as before. My first tip that something was different is that after about 10 rinces that mud was still showing positive for copper (ammonia test). I finally got it to a very light blue so decided to dry it on the electric hot plate. 1 hr later it looked like charcoal powder and only weighed 1 ounce. When I tried to melt it I saw there was stuff in it that wanted a much higher temp to melt. I put 65 grams of silver scrap left over from earlier and poured the most gosh awful looking stuff I have ever seen! Now I don't know what to do with it. Should I throw it back in nitric?


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## Anonymous (Feb 18, 2013)

mikeinkaty said:


> The reason I ask is that I just dropped 25 ozt of silver with copper (all in one bucket). After the clean-out I put more copper in the spent solution and set it aside for a couple of days. The first 25 oz made light grey very fine particle and heavy mud that turned into nice looking 990 bars. The dried mud was real pretty light grey in color. Then I recovered about 3 oz of cement from the spent solution bucket I had set aside earlier. It was light grey curdey looking stuff - not a mud as before. My first tip that something was different is that after about 10 rinces that mud was still showing positive for copper (ammonia test). I finally got it to a very light blue so decided to dry it on the electric hot plate. 1 hr later it looked like charcoal powder and only weighed 1 ounce. When I tried to melt it I saw there was stuff in it that wanted a much higher temp to melt. I put 65 grams of silver scrap left over from earlier and poured the most gosh awful looking stuff I have ever seen! Now I don't know what to do with it. Should I throw it back in nitric?


If I'm incorrect, the other members will correct me. But this is what I would do.

*No# 1.* Crush the powder, or if it's really powdered, put it in 50/50 nitric/H2O or Peroxide, and let it dissolve, if it does.
*No# 2.* After it dissolves, I would filter it to a different beaker/vessel.
*No# 3.* Take the still, filtered paper, with possible powder in it and add equal amounts of HOT Distilled water or peroxide and add it to the new vessel you just filtered to (through the same filter).
*No# 4.* Place a piece of clean copper in the solution that you poured the main and rinse solution in. It should start cementing your silver.
*No# 5.* After all the silver have cemented (you'll know because the copper won't attract anymore silver after it cements to the bottom of the vessel and stays there).
*No# 6.* Test the solution with a stannous test to make sure no other PMG's are in the solution. If silver is still in there, the copper would pick it up and cement it, then drop it out of the solution. If not, you probably don't have any silver in the solution. If you do, it won't be much if the copper piece you have shows very little degrading and no silver sludge on it.
*No# 7.* Do a pH test to make sure you neutralize the solution.

If there are any other PM's in the solution, the stannous test will tell you so. 

I hope I explained this correct. If not, please correct me.


Kevin


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## Geo (Feb 18, 2013)

any metal less reactive will cement on copper. there is a certain amount of gold and other impurities it silver. Rhodium is used to coat silver so that it keeps its luster longer before it starts to tarnish. Rhodium will not dissolve in nitric but it will break down into powder so fine its hard to see with the naked eye. lead can get into the mix and like tin in gold refining, will follow silver to the end of the process. you can add a few drops of sulfuric to your solution before you cement if you suspect lead and filter. sounds like you had some oxides in the mix. oxides turn into a black syrupy mass when you try to melt.


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## mikeinkaty (Feb 19, 2013)

I forgot to say that this was a Gorham serving tray, nothing else. 

Why was it the last drop? Nothing at all out of the ordinary showed in the 1st drop. Like I said, after first letting the copper run to apparent completion, I recovered the cement then put copper in the spent solution. It was the dropped stuff from the spent solution that caused the mess. The first drop was clean as a whistle. The copper I used was buss bar stuff (high quality) and I even used the same bars in the last drop. I also cleaned the bars with a wire wheel before the 2nd.

Do the other metals tend to drop out after the silver is gone? The 1st silver dropped was 91% of the original sterling weight so it was close to all expected silver.

One other thing. When I did the ammonia test, it would first turn blue then after a few minutes this dark brown cloud would appear in the test beaker and was looking like it was wanting to congeal. The ammonia tests on the first drop did not do that and only about 4 rinces got rid of all color.

Mike


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## Geo (Feb 19, 2013)

copper is not infallible. perhaps the bussbar was contaminated inside. when metals cement, the most reactive will cement first followed by the next to be replaced in solution. so silver will cement out before Pd,Hg,Pt and gold is last. this is according to the electromotive series. if the metal was contaminated with any other metal, it would show up last. this may not be the problem though. like i said, the way you described it sounds like an oxide to me. black, viscous melt.


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## amesametrita (Feb 19, 2013)

mikeinkaty said:


> The reason I ask is that I just dropped 25 ozt of silver with copper (all in one bucket). After the clean-out I put more copper in the spent solution and set it aside for a couple of days. The first 25 oz made light grey very fine particle and heavy mud that turned into nice looking 990 bars. The dried mud was real pretty light grey in color. Then I recovered about 3 oz of cement from the spent solution bucket I had set aside earlier. It was light grey curdey looking stuff - not a mud as before. My first tip that something was different is that after about 10 rinces that mud was still showing positive for copper (ammonia test). I finally got it to a very light blue so decided to dry it on the electric hot plate. 1 hr later it looked like charcoal powder and only weighed 1 ounce. When I tried to melt it I saw there was stuff in it that wanted a much higher temp to melt. I put 65 grams of silver scrap left over from earlier and poured the most gosh awful looking stuff I have ever seen! Now I don't know what to do with it. Should I throw it back in nitric?




I bet the pH of you solution raised.


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## mikeinkaty (Feb 19, 2013)

Geo said:


> copper is not infallible. perhaps the bussbar was contaminated inside. when metals cement, the most reactive will cement first followed by the next to be replaced in solution. so silver will cement out before Pd,Hg,Pt and gold is last. this is according to the electromotive series. if the metal was contaminated with any other metal, it would show up last. this may not be the problem though. like i said, the way you described it sounds like an oxide to me. black, viscous melt.



The serving tray was heavily tarnished! I just remembered that. Maybe I better clean with diluted HCL before disolving??


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## mikeinkaty (Feb 19, 2013)

amesametrita said:


> mikeinkaty said:
> 
> 
> > The reason I ask is that I just dropped 25 ozt of silver with copper (all in one bucket). After the clean-out I put more copper in the spent solution and set it aside for a couple of days. The first 25 oz made light grey very fine particle and heavy mud that turned into nice looking 990 bars. The dried mud was real pretty light grey in color. Then I recovered about 3 oz of cement from the spent solution bucket I had set aside earlier. It was light grey curdey looking stuff - not a mud as before. My first tip that something was different is that after about 10 rinces that mud was still showing positive for copper (ammonia test). I finally got it to a very light blue so decided to dry it on the electric hot plate. 1 hr later it looked like charcoal powder and only weighed 1 ounce. When I tried to melt it I saw there was stuff in it that wanted a much higher temp to melt. I put 65 grams of silver scrap left over from earlier and poured the most gosh awful looking stuff I have ever seen! Now I don't know what to do with it. Should I throw it back in nitric?
> ...



I think you hit the nail on the head, so to speak! Found this on Google: " Cu(OH)2. Copper hydroxide is a pale blue, gelatinous solid". That is what the stuff was in the ammonia test beaker! I had dumped to much rince water in the waste bucket! I think this may be why I've had problems in the past. I had ask here how much to dilute and never got a definitive answer - at least one that I understood. I generally have been doubling the volume before cementing by adding distilled water.

This generally means that one cannot dilute the AgNo3 solution to much. I was way beyond a 50% dilution in the waste bucket. What does the Ph curve look like when the silver is dropping? In other words, how does it change as more and more silver drops out?

I got to get me a Ph meter. I should keep the Ph below 4 ??

Another lesson learned. DO NOT add the rince water to the original solution until after it is totally devoid of silver!

Mike


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## amesametrita (Feb 19, 2013)

mikeinkaty said:


> I think you hit the nail on the head, so to speak!



There is no magic here, just education and experience.


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## FrugalRefiner (Feb 19, 2013)

amesametrita,

I found your silver cell posts interesting. I couldn't follow your initial post because it was so brief. Once you took the time to elaborate, I learned from you. 

Recently you criticized a user's silver cell design, again in equally brief fashion, with no explanation as to why you didn't like it or what could be done to improve it. 

This is just my opinion, but perhaps if you provide a little more information when you post, others would not be as critical. If it's too much trouble for you to do this, perhaps you should wait to post until you have a little more time to do so with enough detail to help those of us who are less experienced to understand your position.

I, for one, come here to learn about recovery and refining. I read all posts and try my best to learn from them all. If you choose not to post on the open forum, you defeat the purpose of being here. I would personally prefer to see all advice given in the open so we can all learn from you.

Dave


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## kjt124 (Feb 19, 2013)

Agreed.

I think the main issue here is more of a language barrier than anything... I have had friends from many countries and in some places a very short and direct approach to information exchange is appreciated.

Unfortunately for most people in the US I know it is taken unfavorably - sometimes as insult.

amesametria - you clearly have the knowledge and you are here so you are likely willing to share. Don't clam up now, just learn to play nicely like everyone else has to. I for one find the exchanges between you and the celebrities on here thrilling. It is nice to get information at such a rate! So, have at it - what is wrong with copper cementation of silver (or perhaps with the way it is being done here)? What would be better for the small scale operation?


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## mikeinkaty (Feb 19, 2013)

"What does the Ph curve look like when the silver is dropping? In other words, how does it change as more and more silver drops out?"

Anybody?

If not, then I just bought a Ph meter and I'll post the answer here when it gets here assuming I can operate the thing! 
Mike


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## amesametrita (Feb 19, 2013)

Actually cementation is electrochemical reaction.


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## amesametrita (Feb 19, 2013)

Digital pH meters don't like silver solutions.


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## g_axelsson (Feb 22, 2013)

Unless you have excess nitric in the solution when starting the cementation there shouldn't be a large change of pH. As two silver ions in solution turns into solid metal, one copper atom turns into an ion and goes into solution.
Nothing in that reaction affects the concentration of H+ ions in solution so the pH should stay constant.

Evaporation of water and free acid on the other hand could easily change the pH.

Göran


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## amesametrita (Feb 22, 2013)

not sure


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## Geo (Feb 22, 2013)

for me, a little silver loss is the lesser of two evils (but thats just me).

"Actually cementation is electrochemical reaction.
Any good enough ion in vicinity of the bar will jump to it.
So, electromotive series show only possibility of reaction.
Kinetics depends on concentration (first) and oxidation state (second).
Moreover, more reactive metals could be re-dissolved by nobler ones cementation."

how quickly does this happen in the reaction? i may be totally off the mark but i was trying to explain why the first part of the cementation could be cleaner than the last part. he said the first parts of the cementation was cleaner. i was just using what he observed. if the above was totally accurate, then the first part of the cementation would have been the same as the last part. by your on explanation, what he described should have never happened.when cementing, and the first part of the cementation looks clean and melts clean and the last part looks contaminated and melts contaminated, that means that it did not cement out over the whole process the same way. 

i didnt go to school to learn this stuff and all i have to go by is what ive learned here, if a member says "this is what happened", im not going to say its impossible. im going to try and figure out why it did what it did.


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## amesametrita (Feb 22, 2013)

By the way, the main contaminant of the last cemented silver is copper itself.
Not chemical but mechanical contamination.


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