# Whats in my copper nitrate.



## jay2000 (Mar 31, 2012)

Hello all,thanks to good info from posters and a large dose of Hokes book,my E scrap refining whent surprisingly well.I have now started on refining silver contact points(about 13 kgs worth),in processing i have accumulated a couple of gallons of copper nitrate from cemented out silver nitrate,i tested the batches with pure hydrochloric to see if complete cementing had happened,no cloudy residue other than blue/green colour,then with ammonia and got a cheesy ink blue reaction,then tried stannous and to my surprise got a brown turning to black reaction similar to platinum,is this reaction a false positive as i have assumed all values would have cemented out with the silver,to reduce space i evaporated out a gallon of liqued and now have a slab of copper nitrate,if their are any values in it how do get past all that copper??,


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## Harold_V (Apr 4, 2012)

jay2000 said:


> Hello all,thanks to good info from posters and a large dose of Hokes book,my E scrap refining whent surprisingly well.I have now started on refining silver contact points(about 13 kgs worth),in processing i have accumulated a couple of gallons of copper nitrate from cemented out silver nitrate,i tested the batches with pure hydrochloric to see if complete cementing had happened,no cloudy residue other than blue/green colour,then with ammonia and got a cheesy ink blue reaction,then tried stannous and to my surprise got a brown turning to black reaction similar to platinum,is this reaction a false positive as i have assumed all values would have cemented out with the silver,to reduce space i evaporated out a gallon of liqued and now have a slab of copper nitrate,if their are any values in it how do get past all that copper??,


If you have DMG, check with that to see if you get a yellow precipitate. The barren solution should be blue, so if it has a green hint of color, leave copper in for some time after you have recovered all of the silver. What you are seeing may be either palladium (my first guess), or even traces of platinum. Both will make the copper solution lean towards green, but platinum won't yield a dark reaction with stannous chloride. Can't say what may be causing the color reaction otherwise. Dunno!

Try testing the solution (with stannous chloride) wthout having added any ammonia. Does it respond the same way? 
When the silver was almost fully cemented, did you notice any fine black material coming down? Perhaps coating the copper?
What was the source of the contacts?

Harold


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## jay2000 (Apr 5, 2012)

Thanks for the answer Harold,have got some Dmg on its way,so will test with that,stannous on its own gives a reaction of dark yellow going black quite quickly,this made me think platinum,i think in Hokes somewhere it said that if a percentage of platinum in silver will dissolve in hot nitric,the contacts came from very large units and about a kg of silver elements from high amperage fuses,about 500g of contacts didnt dissolve so am guessng they might be tungsten.Is there a physical test for tungsten?i have touched one to a grinding wheeland no sparks appeared and even after stewing in hot Nitric their was no change in size and just as hard and unbendable as before they went in,hoke says that there are some contacts that are platinum mixes that are difficult to dissolve in AR,have i struck lucky (or unlucky),the liquid colour is dark blue but not a clear crystal blue if that makes sense,if i keep a copper bar in the liquid for some time will it eventualy cement out all the values even if all the silver has dropped out already,i did notice some fine black dust? in with the cemented siver when washing the sediment was this gold?,if it was, its gone into new melted bars DOH!!,any more pointers would be much appreciated gents.


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## Harold_V (Apr 6, 2012)

jay2000 said:


> Thanks for the answer Harold,have got some Dmg on its way,so will test with that,stannous on its own gives a reaction of dark yellow going black quite quickly,this made me think platinum,


Platinum would yield an orange through dark brown color, assuming there's enough present, but it would also alter the color of the solution you speak of. If it's blue, there's little chance that you have platinum present, although it could contain traces for some reason. 



> i think in Hokes somewhere it said that if a percentage of platinum in silver will dissolve in hot nitric,


Correct. However, like I said, its presence would also alter the color of the solution. If it's blue, but started out with a green hue, it may have been cemented. Usually was slow to come down in my experience, usually after the silver was down. It generally yields a black powder. 



> the contacts came from very large units and about a kg of silver elements from high amperage fuses,about 500g of contacts didnt dissolve so am guessng they might be tungsten.


While it may not be true of all tungsten contacts, the vast majority have a waffle pattern on the back side. If you find that pattern, know that the silver is slow to leach--it may require a few hours of boiling in a covered beaker. When all of the silver has been extracted, a contact will break easily under thumb pressure. If it is difficult to break, and shows a distinct line in the center, regardless of the size of the line, silver remains. When it has all been recovered, the line will no longer be visible. 



> Is there a physical test for tungsten?i have touched one to a grinding wheeland no sparks appeared and even after stewing in hot Nitric their was no change in size and just as hard and unbendable as before they went in,


I know of no test, although there may well be one. However, what you have described should be well addressed by my previous statement. If they're difficult to break, they still contain silver. 

[/quote]hoke says that there are some contacts that are platinum mixes that are difficult to dissolve in AR,[/quote]
One should never use AR for contacts unless they are known to be gold or platinum. If silver contacts are subjected to AR, the values will not be dissolved due to silver being, for all practical purposes, insoluble in AR. 



> have i struck lucky (or unlucky),the liquid colour is dark blue but not a clear crystal blue if that makes sense,


It does make sense, and that's a perfect sign that you are working with tungsten. In fact, if you add a little HCl to the recovered silver (cemented on copper), the resulting color should be a dark inky blue. 



> if i keep a copper bar in the liquid for some time will it eventualy cement out all the values even if all the silver has dropped out already,i did notice some fine black dust? in with the cemented siver when washing the sediment was this gold?,if it was, its gone into new melted bars DOH!!,any more pointers would be much appreciated gents.


Yes---if there's any values included, they will eventually cement and will report in the silver. 

If you are melting the silver and pouring bars, you may not be doing a wise thing. All depends on your objective. If you are recovering traces of values of other metals, the silver should be parted in a silver cell, to ensure quality, and to recover the traces that are contained within. Give some thought to running a silver cell unless you aren't concerned about these issues. 

Harold


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## jay2000 (Apr 6, 2012)

Thankyou for the comprehensive answer Harold,i had forgotten that silver in AR was a no no,the undissolved contacts dont have a waffle pattern or a visible line through them,some are about the size of a UK 10p piece(US dollar perhaps)and about 3 to 4mm thick and the others are 25mmx10mm and of similar thickness,i do remember that they took a lot of heat from a burning torch to unsolder them,should i boil up a couple in AR to see if any dissolution happens.
I have a copper bar in the solution i have left,and a black soot(for want of a better word)is forming on the bar, is this the black powder that will eventualy drop to the bottom,also the liqued is starting to go clearer,i have thought about a silver cell but providing i can get as near to 925 with out using a cell,the cost/time involved for the extra effort,financially doesnt quite get there,(9p difference between 925 and 999 in the uk) and i believe anodes have to be quite pure anyway,(the crystals do look very pretty though :lol: ),Regards.


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## butcher (Apr 6, 2012)

The silver cell suggested was to be able to recover PGM, and gold in slimes of the silver cell, if you do go through a lot of silver it may be wroth giving it a second thought.

Unless the contact was very high in gold or PGM (highly unlikely) content aqua regia would not work, as contact points are normally mainly silver and base metals with small amounts of gold or other PGM's possible, nitric acid not aqua regia should be your choice.

Leach in Hot nitric, the first leach could have removed all the silver the acid can hold, a second hot leach may be needed, in your picture you did seem to have quite a bit of silver left, I would leach as much as possible and break, crush smash the remaining material to attempt to recover what may be trapped inside. Many of the contacts 
larger current type contacts are tungsten they should break when most of the silver has been removed.


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