# Manuel needs your help



## Juan Manuel Arcos Frank (Dec 8, 2010)

Does anybody know how to dissolve anodically a 0.900 silver bar ?

This is why I am trying to do:

I want to dissolve in an electrolytic cell many kilos of silver bars(0.900) to get a concentrated silver nitrate solution which will be cemented with copper.I know there are many other processes to do it,but I like the process because it is very cheap,no fumes and not much labor.

The cell has a volume of 13 lt,(12 lt distilled water,1 lt nitric acid 68% and 250 gr. of 0.999 silver dissolved),the 0.900 silver bar is on the anode,the cathode is a 0.999 silver foil,current applied is 10 A,the voltage is 10 V so the cell runs nicely and the bar is dissolved in 29 hrs,very nice crystals are formed on the cathode(from a 1020 grs(0.900) bar I got 872.27 gr. of silver crystals and 45.3 grs. of silver are in solution,as silver nitrate)but I do not want the crystals,besides,after 3 bars(3 kg.of silver 0.900) those nice crystals become an ugly dark mud and copper starts deposite on the cathode.

How can I stop crystal growing?...I just want to dissolve the silver bars to obtain a concentrated silver nitrate solution.What am I doing wrong?

Any help will be appreciated.

Kindest regards.

Manuel


----------



## HAuCl4 (Dec 8, 2010)

It seems you need more nitric acid.


----------



## Palladium (Dec 8, 2010)

I'm kind of lost or maybe i missed something. If all you want to do is get a concentrated solution of silver nitrate and cement it out of solution can't you just dissolve it in nitric and cement with copper? Why the electrolysis? Is there a difference?


----------



## nickvc (Dec 9, 2010)

Manuel sorry if I'm missing your aim in this process...
I think your aim is to re run the cemented silver through your cell as the feedstock is not ideal for creating fine silver at one pass...if this is the case I think the only way is to make new electrolyte before it becomes copper rich. Cement your silver out of the electrolyte and use your crystals to make the new one, your going to have to do this quite often until you have a good surplus of fine silver, then I'd melt the bars with the fine to improve the feedstock and allow the cell to run without constant changes of the electrolyte, hard work to start but becoming easier at the end. GSP I think might have a better insight into this and hopefully will add his comments.


----------



## goldsilverpro (Dec 9, 2010)

Manuel, old friend,

Unfortunately, with a standard cell, you cannot avoid the silver from depositing onto the cathode. If the silver dissolves, it is going to also deposit. The only way to solve the problem is to place a membrane between anode and cathode. That way, the silver will dissolve, as normal, but will be prevented from from coming in contact with the cathode and you will end up with a silver nitrate solution . You can also used a porous cup to set up a fizzer cell arrangement and achieve the same results. Awhile back, I posted a link that had a photo of one. Search for fizzer cell.

Chris


----------



## Juan Manuel Arcos Frank (Dec 10, 2010)

HAuCl4:

Thanks for your input.I am trying to use the minimum of nitric acid,I mean,dissolving the greatest quantity of silver ingots with 1 lt of nitric acid.

Regards.

Manuel


----------



## Juan Manuel Arcos Frank (Dec 10, 2010)

Palladium:

Thanks for your advice,you are right about nitric acid/cementation process but why I am trying to do is dissolving the greatest silver quantity in the minimum nitric acid,without fumes,low labor(including while I go to sleep) and recover copper too,this is a kind of green chemistry process.

Of course,I am not reinventing the wheel,this process has a name,it is a forgotten process named Dietzel.I am posting a link to download an old book about electrochemistry:

http://www.archive.org/details/appliedelectroch00thomrich

Dietzel Process is depicted on page 58.

Regards.

Manuel


----------



## Juan Manuel Arcos Frank (Dec 10, 2010)

nickvc:

Thanks for your coments.

It is not my goal to obtain 0.9999 silver crystals,the anode silver bars are 0.900 but they contain all kind of base metals,like copper,nickel,cadmium,iron,mercury,tin and so for...The process that I am trying to run has many advantages(solid silver ingots can be dissolved,any silver content from 0.100 to 0.900 and copper is recycled).

If this process works well then I will try to make 0.9999 silver,I hope.

Kindest regards.

Manuel


----------



## Juan Manuel Arcos Frank (Dec 10, 2010)

Chris,My Good Friend:

I do appreciate all your advices.

If I would know 10% of all your knowledge and hands on experience I would solve all my problems.I have read about fizzer cells,Shor patent and semi permeable membranes and I have some questions:

Where in USA can I get a porous cup with semi permeable barrier which works with silver ions and nitrate cathions?,I mean,that stops silver ions to cathode but let passes nitrate cathions to anode.

Could a salt bridge work between anode and cathode if they are separate cells?

What is a breakdown cell?.

Thanks again.

Have a nice day.

Your friend:

Manuel


----------



## goldsilverpro (Dec 11, 2010)

I think that the porous cups pass water and current but everything else is stopped. There are commercial membranes available that pass anions (-) but don't pass cations (+) - called anionic membranes. There are also cationic membranes that work the opposite. You might be able to talk some company into some samples. One manufacturer in the US is Ionics. There are many in Japan. One company is Tokoyama Soda. My spelling of this may be off.

I basically know about salt bridges but have not used them.

A breakdown cell is a regular silver cell used to just tear the bars apart, with no concern about the crystal purity and little about solution control. It is usually used to first "breakdown" lower purity silver = say, 80% to 90% stuff. You then remelt the crystal (maybe 98%-99% pure) and purify it through a clean cell


----------



## Juan Manuel Arcos Frank (Dec 12, 2010)

Chris,My Dear Friend:

I do thank you all your answers.I am working on getting the porous cup.

Have a nice day.

Your friend:
Manuel


----------



## Barren Realms 007 (Dec 12, 2010)

Juan Manuel Arcos Frank said:


> Chris,My Dear Friend:
> 
> I do thank you all your answers.I am working on getting the porous cup.
> 
> ...



Juan,
I think I remember someone useing an unglazed ceramic or clay pot.


----------



## goldsilverpro (Dec 13, 2010)

Coors, the same company that makes beer, is probably the largest maker of ceramic lab items - vacuum filter funnels, porcelain crucibles,and porous cups, etc.


----------



## Palladium (Dec 13, 2010)

Analysis Coors Labware http://www.scribd.com/doc/26692514/Analysis-Coors-Labware


----------



## Lou (Dec 14, 2010)

You might inquire at DuPont about their Nafion membrane. It's some sort of fluoromer that is chemically resistant. I've used it for dialysis back at school, but I understand it has many many uses.


Lou


----------



## dtectr (Dec 14, 2010)

goldsilverpro said:


> Coors, the same company that makes beer, is probably the largest maker of ceramic lab items - vacuum filter funnels, porcelain crucibles,and porous cups, etc.


During Prohibition, 1920-1933, many U.S. breweries closed, never to reopen. Coors, though, created their ceramics line (originally called "porcelain", I believe) toilets, sinks, & etc. They did this, in part, to keep their family of employees employed. 
I learned about that from the *Coors Cookbook*, which covers a lot of their history, I wasn't aware that they still did the ceramics thing, that's kind of cool. 8) 

They merged with & are now owned by Molson from Canada.

For history wonks:
*"While Prohibition was successful in reducing the amount of liquor consumed, it tended to undermine society by other means, as it stimulated the proliferation of rampant underground, organized and widespread criminal activity."* 
http://en.wikipedia.org/wiki/Prohibition_in_the_United_States#cite_note-t100524-3 
I had a distant 'cuzzin' who was investigated & arrested by the FBI for a successful bootlegging operation in Kentucky in the 20's. I'm so proud!! :twisted: :roll: 

It also gave us NASCAR: "NASCAR, an Overview - Part 1." Suite101.com. Google. Web. 22 Nov. 2009

(I'm trying to tie this post back into refining, somehow ...)Oh, yeah-
"Don't drink & drive while you're refining silver!"  :lol:


----------



## goldsilverpro (Dec 14, 2010)

On a Coors tour in Golden, CO, we were told that they first got into the ceramics business in the 1800s, when they made ceramic beer bottles.

I think the Nafion membranes only come in the cation variety. I don't think they make anion membranes.


----------



## Lou (Dec 14, 2010)

Probably true Chris. I remember using them, but haven't had a need to incorporate them into any refining business.


dtectr, I didn't know the FBI was in business back in the 20s  I thought Hoover's boys were from the 30s on?


----------



## Juan Manuel Arcos Frank (Dec 15, 2010)

Barren Realms 007:
Thanks...I am looking for a big cup of beer.Regards

Palladium:
Thanks for the link...Coors has a porous cup of 1 lt.(Cat No. 60495) I am finding out about its cost.

Lou:
I do appreciate your advice.Nafion 315 was used to recover silver from colour paper bleach/fix solutions.Dupont is here in Mexico,but when they heard that I just needed a little bit of their membrane they threw me away.I will ask others Dupont´s clients which usually buy this membrane about if they will be able to sell me a little bit.Have a nice day.

GSP:
How can I make a salt bridge?One of the half cells contains the silver bar as anode,the solution is a mixure of copper and silver nitrate...the second half cell contains pure copper as catode and copper nitrate solution.Lab´s salt bridges are U type glass tube with potassium nitrate that conect both half cells...If I fill a U type tube with saltpeter it will fall out or will contaminate the nitrate solution of both half cells.What kind of solution do I need?.How can I seal the U tube extremes?.Thanks for your help.

Manuel


----------



## Oz (Dec 15, 2010)

Juan,

I have been watching this thread with interest as I do a fair amount of silver. I think you are unnecessarily over complicating this with salt bridges, porous cups, and membranes. 

I am assuming based on the direction you are going, that nitric is more expensive for you than electricity. But if you truly want an end product that is not metallic there is no getting around the fact that your silver nitrate will need approximately 2.38ml of 50/50 nitric (made with half distilled water and half 70% nitric by volume) for each gram of silver you wish as a nitrate solution. 

If you are ok with a metallic silver end product if it was .999 or better I would just digest your .900 silver in nitric, then cement it on copper. Remove your cement silver and cast it into anodes for a silver cell. If you wash your cement silver well you will have very little copper (1% or less) and be able to purify a lot of silver with very little nitric in a silver cell before needing to change out your electrolyte. If you keep your copper below 100 grams per liter in the cell you will not be getting the contamination you are now with your silver crystal. 

With your now copper nitrate solution (after silver cementation and removal of cement silver), push out all the copper you can with DC current onto a copper cathode that has a removable container under it (remove the cathode and basket as you turn off the power). The copper deposit will be spongy and not very adherent to your cathode, but after washing it you can cast it into bars to cement more silver. This also means you do not have to be concerned that ALL the silver was cemented, as if it contaminates your copper you are just using it to cement more silver. You can now reuse your solution to digest more .900 silver since you will have removed most of your copper electrically and have free nitric once again in solution. 

There is little loss of nitric this way. Most that is lost will be as gas when digesting (use small additions to minimize it) not the electrolytic processes as they are rather fume free. I see little extra if any nitric saved with a more complicated process. 

Short of the above, if you do not want to reuse your copper nitrate, I would go with the breakdown cell GSP recommended. I often use one for .925 silver then re-run the crystal in a clean finishing cell. With all of this you are trading labor against nitric costs.

Ps; I just re-read the thread and cementation will get rid of the contaminates you listed except for the mercury. I have to wonder though how you got a .900 “cast” bar that could contain mercury. Are you sure there is mercury present?


----------



## Juan Manuel Arcos Frank (Dec 23, 2010)

Oz:

Thanks for your post.

I am trying to use the minimum of nitric,I mean,to dissolve anodically 5 kg(or more) of 0.900 silver with 1 lt. of nitric using the cell I have mentioned above.Besides,I am trying to avoid melting as far as I can,I mean,to put in a basket all silver jewelry,bars and so for,dip it in the cell as anode and start the process.

I have bought a glass tube(No. 20) just to make the salt bridge,I will fill up the extremes with compressed cotton,after Christmas I will try it.

Mercury comes from old amalgamation ore and battery silver recovery ...The silver I am trying to process it is not my own,it owns to a friend who buy many kilos of silver daily,actually he is refining it with Karo process but he is interested on runing a better and cheaper process.Electrons are the cheapest reactive in Chemistry.

Have a nice day.

Manuel


----------



## Oz (Dec 23, 2010)

Juan,

Let us know how your salt bridge works out for you once you have results.

The reason I asked about the mecury is I thought you had cast bars of silver for anodes. I did not think you would have any mercury not go off as the gas at silvers melting point when you cast it. I know you are aware, but be careful with that mercury.


----------



## Juan Manuel Arcos Frank (Dec 23, 2010)

Oz:

Done!!!!!....

I will try to separate silver from people who recover silver from old ores and try to convince those who break button cells to use the process to avoid mercury.

BTW,the first cell I am runing is a Shor International cell that I am changing to the new process,I will post some pics soon.

Behave yourself.

Kindest Regards.

Manuel


----------



## flexyman (Jan 20, 2011)

Hi Manuel, Place your anode Silver+ in an anode bag . use copper plate as Cathode. Use HCl as electrolyte use 1.5 dc power. Adjust ampage required
by altering the distance between Anode and Cathode. When Electrolyte
passivates adjust PH level of Hydrochloric acid.
You will collect Silver Chloride in Anode bag and all disolved metals will co-plate on the cathode .( Copper + Pd + Au )
In order to make Chloride the Silver takes the Chlorine from the Acid . You
could add Salt to the Electrolyte to replace the Chlorine in the Electrolyte.
Clean the Silver Chloride and reduce to Silver metal.

Have fun.


----------



## Juan Manuel Arcos Frank (Jan 20, 2011)

Hi Flexyman.

It sounds great!!!!...I am making my salt bridge which is almost ready,I will post it ASAP.

Kindest regards.

Manuel


----------



## Drewbie (Jan 20, 2011)

Greetings from Guadalajara, Paisano!

Pachuca - that name stirs up silver mine history, that's for sure.

The story of the miners from Cornwall heading to Pachuca to re-start mining after the war of independence, and later introducing Mexicans to the great game (football) makes for interesting reading...

http://www.poldark-mine.co.uk/mexico.htm

I have a Cornish bloodline (stonemasons), combined with Durham (quarry stonemasons and coal miners) so I think that might be why I find minerals, mining and PM's so attractive.


----------



## Juan Manuel Arcos Frank (Jan 20, 2011)

¡Saludos,mi querido Drewbie!!!!

INDEED!!!!!!!.....British legacy is very large, here in Pachuca last names like Ludlow,Skewes,Hoosking,Rabling and so for are very common,besides British Miners introduced paste up (called here "pastes",a kind of pie),they taught us how to play football soccer and how to enjoy whisky.We are very grateful to them.

Do you know what is the main contribution of the British to universal culture?,....THE SHORT SKIRT!!!!!!!!! invented by Mrs. Mary Quant....Mrs. Quant,wherever you are respectfully I kiss your hand.

Regards.

Manuel


----------



## Drewbie (Jan 20, 2011)

I would KILL for a Cornish pasty right now! Whenever I go to London, I head straight for a railway station, to buy a couple.

And HAZZAH for Mary Quant! Modelos y edecanes fans salute you!


----------



## rusty (Feb 18, 2012)

Juan Manuel Arcos Frank said:


> Hi Flexyman.
> 
> It sounds great!!!!...I am making my salt bridge which is almost ready,I will post it ASAP.
> 
> ...



Manuel do you have anything new to add to this thread regarding your salt bridge.


----------



## flexyman (Feb 19, 2012)

Hi ,once again Manuel,
Why not use a Clorox - HCl leach with mechanical agitation to turn Silver Dore' to AgCl. Agitation removes AgCl coating from Dore'



Have Fun


----------



## lazersteve (Feb 28, 2012)

I agree with Oz. Recycle your copper nitrate solution repeatedly to digest all of the silver.

If getting nitric acid is a probelm, then start out with a 6 Molar solution of copper nitrate crystals to make your first batch of electrolyte.

Steve


----------

