Best way to refine close to 60% silver.

[Amol Gupta]

So my feedstock is close to 60% silver 30% copper and the rest 10% being tin, cadmium and zinc combined.

I wish to recover silver and copper mainly getting back the chemicals used is a bonus.

I wanted to know the best way to refine the copper and silver I am looking for purity 99+, the process being fast is an additional benefit.

So I have a couple of procedures in mind(I open to hearing alternatives).

1. Dissolve the feed in nitric acid, recover silver through cementing on copper. And recover the copper as mentioned in one of the videos of nerdrage()

2. Inquarting the feedstock with copper and running it through the copper cell, collect the slimes and recover the silver by either dissolving in nitric and cementing or run the melted slimes through a silver cell.

Using the first method will result in consuming a lot more nitric than I would like, the copper cell seems pretty slow but I guess that is something that can be speeded up, I'm not sure if I can run the feed directly through the copper cell.

I'd like to discuss the ideas and am open to any other methods.

Thanks regards.

 

[4metals]

I wanted to know the best way to refine the copper and silver I am looking for purity 99+, the process being fast is an additional benefit.

The high copper content makes a silver cell impractical on the raw alloy. This is a job that will benefit from copper cementation to yield a high purity Silver to feed a Silver cell. The cell will work long and well because you will not be dealing with all of the copper in the alloy.

The video you posted from NerdRage will work well on your parting solution which will be primarily copper nitrate and effectively allow you to regenerate some nitric and and recover the copper.

True, the parting of the alloy and cementing the Silver will consume a lot of nitric acid but adding enough copper to the alloy to make it functional in a copper cell which is best when over 95% copper to start will be slow and require a lot of copper up front. At least the Silver cell, after parting and adding 99% Silver as anodes will consume only a minute quantity of nitric acid.

Depending on your process quantities, you may be able to generate enough nitric yourself. Review the NerdRage video's in the video section to see if this is feasible for you.

Unfortunately with copper and Silver refining you are going to consume some nitric. As we say in America, when you make an omelet, you have to break some eggs!

 

[Amol Gupta]

As we say in America, when you make an omelet, you have to break some eggs!

You had mentioned rolling on this one.

Depending on your process quantities, you may be able to generate enough nitric yourself.

I'm guessing here you are talking about recovering nitric acid from my copper nitrate solution from which silver has been cemented out.

 

[4metals]

I'm guessing here you are talking about recovering nitric acid from my copper nitrate solution from which silver has been cemented out.

Exactly, It will have to be distilled to concentrate it but it will yield decent acid. The entire distillation process is not too difficult and is simplified with larger vessels with large openings to facilitate removal of by products and cleaning.

 

[Amol Gupta]

Exactly, It will have to be distilled to concentrate it but it will yield decent acid. The entire distillation process is not too difficult and is simplified with larger vessels with large openings to facilitate removal of by products and cleaning.

Nerdrage uses a platinum coated anode, I was looking for cheaper alternatives, I'm pretty sure I can use graphite rods, is there something else I can use as an inert anode....?

 

[FrugalRefiner]

MMO (mixed metal oxides) might work. I don't know.

Dave

 

[4metals]

I have always used platinum coated titanium anodes when plating a solution out a solution without soluble anodes. They do last a long time. I have no experience with graphite anodes.

 

[Amol Gupta]

MMO (mixed metal oxides) might work. I don't know.

Dave

I'm guessing you are referring here to the anode material, what about stainless steel, it is used as cathode all the time....?

 

[4metals]

what about stainless steel, it is used as cathode all the time....?

The big difference between an anode and a cathode is the different reactions that take place at each.
Anode: The electrode where oxidation occurs, meaning electrons are lost.
Cathode: The electrode where reduction occurs, meaning electrons are gained.

A stainless cathode is great to deposit metals on such as Silver in a Silver cell or Copper where the deposit is peeled off the cathode.

The reaction at the anode is to put the metals the anode is made from into solution. Platinum being relatively inert makes for a decent anode in electrolytic cells, stainless will erode and effect your purity.

 

[Amol Gupta]

The big difference between an anode and a cathode is the different reactions that take place at each.
Anode: The electrode where oxidation occurs, meaning electrons are lost.
Cathode: The electrode where reduction occurs, meaning electrons are gained.

A stainless cathode is great to deposit metals on such as Silver in a Silver cell or Copper where the deposit is peeled off the cathode.

The reaction at the anode is to put the metals the anode is made from into solution. Platinum being relatively inert makes for a decent anode in electrolytic cells, stainless will erode and effect your purity.

I'll try a small sample with graphite rods and to scale things up I'll move to platinum coated anodes.

Thanks for all the help, dissolving in nitric and cementing silver with copper is the way I'll go.

 

[Geber]

I heard if you add another strong acid back to a nitrate solution, nitric acid will form. I have heard that if you dissolve such a starting material in nitric acid, and precipitate the silver with hydrochloric acid, the nitric acid will regenerate. The chloride will crash out with the silver, and if you undershoot there won't be any hydrochloric acid in your solution. Then you can distill that solution and collect nitric acid.

HCl is much less expensive. I have never done this.

 

[Martijn]

I'll try a small sample with graphite rods and to scale things up I'll move to platinum coated anodes.

Thanks for all the help, dissolving in nitric and cementing silver with copper is the way I'll go.

Are you electrowinning (platinum anode) or electro refining? (Dirty copper anodes)
Big difference.

 

[Martijn]

I heard if you add another strong acid back to a nitrate solution, nitric acid will form. I have heard that if you dissolve such a starting material in nitric acid, and precipitate the silver with hydrochloric acid, the nitric acid will regenerate. The chloride will crash out with the silver, and if you undershoot there won't be any hydrochloric acid in your solution. Then you can distill that solution and collect nitric acid.

HCl is much less expensive. I have never done this.

This is the case with adding sulfuric to copper nitrate.

H2SO4 + CuNO3 > CuSO4 + HNO3

 

[Amol Gupta]

Are you electrowinning (platinum anode) or electro refining? (Dirty copper anodes)
Big difference.

We are talking about electrowinning here platinum anodes.

 

[Amol Gupta]

I heard if you add another strong acid back to a nitrate solution, nitric acid will form. I have heard that if you dissolve such a starting material in nitric acid, and precipitate the silver with hydrochloric acid, the nitric acid will regenerate. The chloride will crash out with the silver, and if you undershoot there won't be any hydrochloric acid in your solution. Then you can distill that solution and collect nitric acid.

HCl is much less expensive. I have never done this.

Something I would avoid doing especially if I might have some gold in the sediment.
Hcl could potentially(if added in excess) form aqua regia and put gold in the solution.

 

[Martijn]

We are talking about electrowinning here platinum anodes.

So you have, or will put all metals in solution and want to get the metals out selectively by electrolysis?
I thought you had an alloy and wanted to electro refine it in a copper cell?