Getting Ag from AgNO3 using Cu powder

[hrushi]

Hello
I have been trying this for past few months and found it to be useful and easy to recover Ag from Ag NO3 using Cu powder
I tried for few days and now i want to share with all of you
I could recover 15-25Kg of Ag in just 15-20mins

This is my precipitating vessel

This is my precipitating vessel with stirrer

on left side of vessal there is stirrer which has black handle with PP sheet at its bottom

After putting AgNO3 in vessel and add Cu powder. and stir the sol you will see Ag in tank
you can check Ag is fully recovered by adding Hcl to it if white spots apper after adding Hcl means Ag is Still In Sol
so add Bit more Cu These you hav to do till all Ag is precipitated
I may not be clear in above process
I will try to add video soon.
If any queries ple feel free to ask
Hrushi

_cementation_

 

[Harold_V]

Hrushi,
An interesting process---but you do realize that you can accomplish the same thing with copper pieces, don't you? It's much simpler---all you have to do is put pieces of copper in the silver nitrate solution and wait. The more copper you use, the faster the conversion. Once finished, you simply remove the undissolved pieces of copper, and rinse the copper nitrate from the cemented silver.

The real advantages to using copper pieces is that no particular equipment is required, and it's a lot easier (and likely one hell of a lot cheaper) to obtain solid copper than it is to obtain copper powder.

I'm not trying to detract from your accomplishment---just hoping to point others in a direction that is far easier and not demanding of equipment.

Harold

 

[hrushi]

Hrushi,
An interesting process---but you do realize that you can accomplish the same thing with copper pieces, don't you? It's much simpler---all you have to do is put pieces of copper in the silver nitrate solution and wait. The more copper you use, the faster the conversion. Once finished, you simply remove the undissolved pieces of copper, and rinse the copper nitrate from the cemented silver.

True recovering with Cu bars is much easy but it takes much more time. Every time we have wash Cu rods properly or for long time ow if we keep Cu bars in open air they either turn black or green and if we use those for recovering Ag then we cannot achieve purity

The real advantages to using copper pieces is that no particular equipment is required, and it's a lot easier (and likely one hell of a lot cheaper) to obtain solid copper than it is to obtain copper powder.

true equipment is not required.
we don't have to buy Cu powder we can use Cu powder which we can easily get from CuNO3 which is left with us. Its completely free.
I found this process more easy than electrolytic recovery or recovery using Cu bars
Thanks
Hrushi

 

[goldsilverpro]

Although you'll never get 999 from a cementation process, I would think the purity would be less with Cu powder than with Cu bars, due to possible Cu entrapment. Of course, if you're purifying it further, it wouldn't make much difference.

 

[Oz]

This sounds similar to what I was suggesting to Manuel in another silver thread, only hrushi is not casting his copper sponge to bar form to use in cementing.

The copper sponge would certainly speed things up due to the greater surface area, but I share the concerns of excess copper contamination. Perhaps there is a way around that, that is the best of both worlds. If the material being processed is already bought and paid for, you would know the silver content. Knowing the silver content digested in your solution, you could calculate in grams 90% of the silver content and add 3.4 grams of copper sponge (dry weight) for every gram of that 90%. With good agitation, that should be low enough to assure complete use of the copper sponge in a timely manner and give you 90% recovery as cement silver. After separating your cement silver from your solution, the remaining solution could be put into settling tanks with copper bars to finish recovering the last 10% of your silver. That should give you 1% or less copper contamination if you wash your cement silver well.

It is worth noting that it is the final stages of cementing out you silver that are the slowest. Trying to get that last bit of silver nitrate in a mostly copper nitrate solution to physically touch the copper and cement is the problem. Some method of agitating or stirring the solution will help greatly.

Something to keep in mind when speeding up the cementation process with either greater surface area of copper or by adding heat. The faster you drive the reaction the more NOX fumes it will off-gas. Not a big deal with proper fume control, but it may make a difference if you are re-using your nitrate solutions after reclaiming your copper from them to digest more silver. It depends on if loss of time or nitric costs you the most.

Ps; hrushi, I would enjoy seeing that video of your process.

 

[rbramsey]

The faster you drive the reaction the more NOX fumes it will off-gas. Not a big deal with proper fume control, but it may make a difference if you are re-using your nitrate solutions after reclaiming your copper from them to digest more silver. It depends on if loss of time or nitric costs you the most.

How do you go about reusing your nitrate after copper cementation? and how are you reclaiming your copper?

Richard

 

[Oz]

I made the assumption since they were getting their copper powder for free from leftover nitrate solutions that the were electrowinning the copper. This leaves you a nitrate that is reduced in copper and has free nitric available for digestions.

Electrowinning the copper is done with DC current with an inert anode (such as graphite) and a copper cathode. LaserSteve has written about this elsewhere on the forum.

 

[rbramsey]

Dah, I was having a brain loss moment. I read more into your post than was there. I was thinking you were doing some chemical method, that's what was confusing me.

Richard

 

[hrushi]

I was able to recover 100% of Ag every time without knowing content of Ag in sol and also 999 purity every time
I will surly add video soon
Hrushi

 

[hrushi]

I have added small clip watch this link
http://www.youtube.com/watch?v=5UgWpz7Rhf8
I am going for vacation for few days I will add video of full process as soon as I come back .
Hrushi

 

[4metals]

Are you adding a precise quantity of copper to stoichiometrically replace the silver?

 

[goldsilverpro]

This is a very interesting process and I see merit in it. The copper looked beautiful and pure and I would be very interested in knowing it's source and how you prepared it.

However, I think 4 metals hit on the crux of the situation in this statement:

Are you adding a precise quantity of copper to stoichiometrically replace the silver?

If you are trying to maximize purity, any excess of copper would have a negative effect. Unlike copper buss bars, you can't pull out the excess copper powder and any remaining will contaminate the silver. Too little copper will leave silver in solution. You can't guess on this and there are no accurate visual clues. You need to know (a) The amount of free nitric in the solution and (b) The amount of silver in the solution.

(a) is easily solved by using less nitric than is necessary to dissolve all of the silver in the batch. In other words, when all of the nitric is spent (preferably heating the solution at the end), there should be some undissolved silver remaining on the bottom of the container. Only by doing this will there be essentially zero free nitric. A liter of nitric, diluted to 2 liters with distilled water, will dissolve close to 821 g of Ag or 240 g of Cu. I would use enough nitric yo only dissolve 90-95% of the metal.

(b) is solved by knowing exactly how much silver is in the solution. This is known by either knowing exactly how much silver was dissolved (difficult) or by analyzing the solution. The latter is cheap (about $100 setup cost), fast (5 minutes), and easy to do using the Volhard titration method.

Here's how I would do this for maximum silver purity:

(1) Use only enough nitric (plus distilled water) to dissolve 90-95% of the silver alloy. Heat at the end. If too much nitric is used and all the alloy dissolves, add enough more alloy until all the nitric is spent and some metal remains. Put the remaining metal in the next batch.
(2) Accurately measure the total volume of solution, analyze the silver content, and calculate the total silver in solution.
(3) Depending on how good you are at this, add enough Cu powder to cement between 95 and 99% of the total silver. It takes about .294g of Cu to cement 1g of silver. Instead of mixing by hand, use a stainless paint mixer (one with a chopping action) chucked in a drill or a small motor.
(4) When all the Cu has reacted, remove the stirrer and hang some Cu buss bars or clean pipe in the solution to cement the remaining 1-5% of the silver. Remove and clean off the bars.

Steps (3) and (4) are added because it would be very difficult to determine exactly the amount of Cu needed to cement 100% of the silver.

I doubt if all this will add more than 20-30 minutes of labor to each batch.

 

[lazersteve]

Chris,

You have the copper and silver ratios reversed:

2 AgNO3 + Cu --> Cu(NO3)2 + 2Ag

2 *107.8 = 215.6 g Ag
1 * 63.55 = 63.55 g Cu

215.6 / 63.55 = 3.39 g of Ag per gram of Cu used.

So 1 gram of Cu precipitates ~3.4 g of Ag.

Steve

 

[goldsilverpro]

Chris,

You have the copper and silver ratios reversed:

2 AgNO3 + Cu --> Cu(NO3)2 + 2Ag

2 *107.8 = 215.6 g Ag
1 * 63.55 = 63.55 g Cu

215.6 / 63.55 = 3.39 g of Ag per gram of Cu used.

So 1 gram of Cu precipitates ~3.4 g of Ag.

Steve

Sorry about that. I edited my post. Thanks, Steve.

 

[Barren Realms 007]

He had stated that he adds a little bit of HCL till he gets no white silver cloride reaction reaction and then he seperates the material and adds a copper bar to the liquid to finish the process.

 

[HAuCl4]

I wonder what hrushi's washing procedure is for the silver crystals and if he uses anything to leach the silver crystals after washing and before melting. An hour in ferric chloride with stirring cleans up pretty much any excess copper and leaves silver 999+ with iron traces as the main contaminant.

4metals formate method seems more straightforward though (haven't tried it yet).

edit: I just saw the video and his stirring tank is made of...steel, and he is adding HCl...voila ferric chloride is in there somewhere!. 8)

 

[machiavelli976]

Wow! Ferric chloride is been used for a long time for etching silver . The byproduct is silver chloride of course. Another mess :lol: Steel (iron) and HCl don't react resulting ferric chloride , but FeCl2. And that tank looks pretty stainless :roll:

 

[4metals]

The thing that interests me about this is the ease of treating the waste acid. In a formic reduction a complex is formed which is a pain to break causing extra steps and specialty chemicals to clean up the acid.

When treating old sterling silver it is not uncommon to find 0.5 parts per thousand of gold in the silver. In this method the lack of filtration before adding the copper would leave the gold in with the silver. Also any palladium, which can also be in old sterling, will be in the silver as well.

What I think Hrushi meant by adding hydrochloric was testing a drop of the blue acid in water containing a few drops of hydrochloric. Any silver still in solution will turn a cloudy white. I do not think he is adding hydrochloric to the silver nitrate.

 

[Barren Realms 007]

The thing that interests me about this is the ease of treating the waste acid. In a formic reduction a complex is formed which is a pain to break causing extra steps and specialty chemicals to clean up the acid.

When treating old sterling silver it is not uncommon to find 0.5 parts per thousand of gold in the silver. In this method the lack of filtration before adding the copper would leave the gold in with the silver. Also any palladium, which can also be in old sterling, will be in the silver as well.

What I think Hrushi meant by adding hydrochloric was testing a drop of the blue acid in water containing a few drops of hydrochloric. Any silver still in solution will turn a cloudy white. I do not think he is adding hydrochloric to the silver nitrate.

After putting AgNO3 in vessel and add Cu powder. and stir the sol you will see Ag in tank
you can check Ag is fully recovered by adding Hcl to it if white spots apper after adding Hcl means Ag is Still In Sol
so add Bit more Cu These you hav to do till all Ag is precipitated

His english in the thread seems to be pretty good, hopefully he will be back soon and clarify what he is doing

 

[machiavelli976]

I would be tempted to use some kind of ultrasonic device to shake like hell that mixture. I can imagine every silver crystal hiding a tiny grain of copper , larger than obtained from usual cementing. 99% silver purity, no way.