My Refined Silver is not Coming Out Pure. Help!

[achab86]

I've decided to go the AgCl route since I think it will be faster than dropping with copper. But I will not forget this for the future!

Copper cementation is much simpler than going the AgCl route, assuming you do the dissolving/cementation properly (which you obviously haven't done). It's easy to drop the AgCl but the steps afterward are not that simple. It's not easy to get all the AgCl converted and I doubt if the purity will be any better than cementation, mainly because the AgCl is more difficult to rinse.

AgCl is something my refinery deals with regularly, so it shouldn't be hard.

Right now I'm more concerned with what happened since I re-digested everything. Today there was a solid (green-blue) clear film on the top of the solution. I mixed the solution and the film fell to the bottom in pieces. Kinda looks like broken glass at the bottom of the solution. I put the solution on heat and the crunchy stuff disappeared. Once the heat was turned off, it started to crystallize.

Is this something I should be concerned about?

 

[Palladium]

I've had it happen before also. It's some sort of copper skim on the surface. Usually happens when you have a lot of copper trash in your cemented silver like you did. I don't know if it's oxides or what you would call it that doesn't digest. All i know is from what i observe. If you find a swamp or standing pond of water that has a high iron content in the water the same kind of skim will manifest it's self. Filter and proceed.

 

[Lou]

Mostly likely supersaturation of silver/copper nitrate from the common ion effect.

 

[kurtak]

. Only thing worse than washing AgCl to me is washing my silver nitrate from tin when i run brazing alloys.

or contactor points

Kurt

 

[GotTheBug]

I can't decide if Palladium is a gold mine or a silver mine of info...

 

[Palladium]

I wish i could claim all the credit and say i'm that smart, but everything i have learned has been through hard work and the generosity of others sharing their knowledge with me. Just passing it along!

 

[Palladium]

Another pointer about that skim/slime. You said you had i think 11,000 ml ? That could be a little or a lot depending upon your flask and buchner funnel size. If you doing it in a table top funnel then you should have enough surface area on the paper that it shouldn't clog up or matter anyway. If done in a small buchner and flask then it is important to not let the solution run dry and pack down the filter paper. Always keep some depth of fluid in the funnel covering the paper. Once it gets low pull the vacuum and add more solution, then reconnect. Once it draws down to the paper it will clog it up. Your filtering speed will increase dramatically. Not that you probably don't already know this, but we have some readers it may help.

 

[Juan Manuel Arcos Frank]

Achab86:

If done properly,both processes,Cu cementation and AgCl precipitation,work well.

About Cu cementation you must be sure that your Cu bar is extra pure,I mean,If your copper bar is contaminated with iron,aluminium or zinc then CuNO3 present in the nitric solution will precipitate as Cu metal!!!!!! and that is why you are getting impure silver with a high Cu concentration,besides,Cu cementation is a reversible reaction,I mean:

AgNO3+Cu=Ag+CuNO3

so to push reaction to the right side you have to add enough pure copper(in my own experience,for 1 gr of silver expected add 5 gr. of copper).Another trick is to dilute the nitric solution in proportion 1:5 with distilled water to avoid that nitric acid dissolves the silver which falls down from the copper bar.

Transforming AgCl into metallic silver is easy too...you can use Karo´s syrup process or nails process.

In both process,after getting the silver mud,a melting technique must be used to yield 0.999 silver,I add some potassium nitrate as oxidant flux.

I hope it helps.

Kindest regards.

Manuel

 

[nickvc]

Achab86:

If done properly,both processes,Cu cementation and AgCl precipitation,work well.

About Cu cementation you must be sure that your Cu bar is extra pure,I mean,If your copper bar is contaminated with iron,aluminium or zinc then CuNO3 present in the nitric solution will precipitate as Cu metal!!!!!! and that is why you are getting impure silver with a high Cu concentration,besides,Cu cementation is a reversible reaction,I mean:

AgNO3+Cu=Ag+CuNO3

so to push reaction to the right side you have to add enough pure copper(in my own experience,for 1 gr of silver expected add 5 gr. of copper).Another trick is to dilute the nitric solution in proportion 1:5 with distilled water to avoid that nitric acid dissolves the silver which falls down from the copper bar.

Transforming AgCl into metallic silver is easy too...you can use Karo´s syrup process or nails process.

In both process,after getting the silver mud,a melting technique must be used to yield 0.999 silver,I add some potassium nitrate as oxidant flux.

I hope it helps.

Kindest regards.

Manuel

And our resident silver refiner gives his much needed advice, if Manuel says do it then just follow his advice...