Processing metal chlorides and nitrates - how to get copper?

[Moje]

Hello,

We have a solution of lots of metals(Ag,Al,Cu,Sn,Pb,Fe,Pt,Pd,some others chlorides and nitrates) - note that no Au

I'm trying to figure out how to remove silver and copper and possibly palladium from the solution
There are 2 ways how to proceed, as far as we've researched for Ag and Cu, but both have drawbacks.
Remove silver from the solution chemically and then remove copper electrochemically - any idea how to remove silver(and only silver) from the solution?
remove both electrochemically - doable, but takes a long long time and exact voltage, as you have to separate metals one by one each with different voltage and cathode/anode.
Also, any idea how to remove palladium directly(or any other metal - the less toxic waste we produce, the better )?

Any way could possibly be used(precipitation, chelation or adsorption(and further melting), crystallization by drying).

Thanks for any help
Mark

 

[NoIdea]

Hi Mark – I thought I would jump in first.

I currently process similar waste; firstly I add a little dilute sulphuric acid to drop the lead as sulphate, filter, the filtrate goes into a container with granulated copper (large surface area and PM’s are easily dislodged by light agitation) covering the bottom. Silver, Platinum, Palladium, and any other PM’s in solution will displace copper, filter.

The filter-cake produced from above, contains your PM’s, how you treat them is right here in the forum.

The copper rich filtrate is treated big pieces of low carbon iron, dropping copper as copper powder, filter.

I have been treating the last filtrate, after treating with iron, with scrap aluminium foil obtained from the pyrolysis of electrolytic capacitors, and filter. I have NoIdea what is in the filter-cake; I am just drying saving it.

The filtrate is being evaporated in an attempt to recover hydrochloric acid via heat treatment of the crystallized aluminium chloride hexahydrate end product.

The advantage of using different metals to drop your value rather than chemicals is that you are not adding extra liquids.

To date, I am evaporating the aluminium chloride solution, six litres complete, thirty litres to go.

It might pay to remove all traces of nitrate from your solutions before starting.

I have had no problems, yet.

Hope this helps.

Deano

 

[Moje]

@NoIdea : Thanks a lot for directions - will try and check it out. Will post in a week or two update how we are doing.

Any idea how scalable this process will be? I expect to be working with more than 100kg batch a time.

 

[NoIdea]

@NoIdea : Thanks a lot for directions - will try and check it out. Will post in a week or two update how we are doing.

Any idea how scalable this process will be? I expect to be working with more than 100kg batch a time.

Hi Moje - Scale should not be a problem, instead of finely divided copper, I would use copper pipe.

Filtering would be the next thing I would look at, I use paper Mache for my filter bed, which means filter size is only limited by your imagination. Mache filters finely divided material, even mud.

I also use a 24hr drop time for both the copper drop and the iron drop, the aluminium drop is left for 48hr with agitation every now and again.


Regards

Deano

 

[4metals]

Generally speaking, NoIdea has more of an idea than his name implies, his suggestions are a good approach. You don't list concentrations of the PM's so it is difficult to determine if what I am posting is valid but DMG (dimethylglyoxime) will drop out Pd from the filtered solution and it can be filtered off and collected. DMG is expensive so this is only valid in low Pd concentrations but removing it from the silver, platinum, palladium mix first leaves the silver and platinum remaining and a perfect candidate for cleanup in a silver cell while collecting the Platinum in the slimes of the cell.

The Palladium will dissolve with the silver in the cell and can build up to levels causing problems.