[RogueRose]

I have some alloys that are 70/30 copper/zinc  and some that are 60/25/15  Zn/Al/Cu and I was wondering what is the best way to seperate these metals using either acids or bases and or electolysis.  I also have access to a forge that can melt all of these up to a temp of about 2500F.  I DO NOT want to boil zinc as I have no means of condensing something like this currently.  IDK if a stainless steel still would work, but I would be afraid of ruining it with remnence from the process. 

The thing is that whatever I use as an acid or solvent I would like to be able to recover if possible by distillation, gas capture or bubbling through other compound. 

I was thinking about dissolving these in nitric acid and using solvents

Zinc nitrate
melting points:
230 °F (anhydrous)
114 °F (trihydrate)
98 °F (hexahydrate) decomposes to Trihydrate
Soluable in alcohols
Decomposes to ZnO and NO2

Copper nitrate melts
melting points:
493 °F(anhydrous, decomposes)
238 °F (trihydrate)
80 °F (hexahydrate, decomposes)
Soluable in alcohol, water and ammonia
insoluable in ethyl acetate

Aluminum Nitrate
 melting points:
151 °F; 339 K) (anhydrous)[1]
165.0 °F; 347.0 K) (nonahydrate)
Soluble in ethanol, methanol and ethelyne glycol

I considered then adding NaOH or a carbonate

I also looked at Sulfuric acid as an alternitive to HNO3.  in Wiki ZnSO4 is soluble in "alcohols" and CuSO4 is insoluable in ethanol.  Looking at other sources it states it is insoluble in ethanol.  AlSO$ is "slightly soluable in alcohol" as per wiki. 

I can't count the times I have gotten conflicting info from Wiki, so Ihave come here to seek advice.  What would be the best way to do this? 

Also, dissolving Cu in H2SO4 is VERY slow even with heat (150-190F) and a concentration from 31% to 93.  It works very well when I use 35% H2O2 but that gets expensive and I think it wastes a lot.


Next I need to figure out Pb, Zn, Sb and maybe Sn seperation. 

Any help is greatly appreciated! 

[Arkcon]

Well, there's an idea  inside your post, if copper reacts slowly with sulfuric, and not at all with HCl,  but the others do, maybe you can use that to your advantage.  Can you write out a plan like that?

[RogueRose]

Well, there's an idea  inside your post, if copper reacts slowly with sulfuric, and not at all with HCl,  but the others do, maybe you can use that to your advantage.  Can you write out a plan like that?

I thought about using HCl for Zn and Al, but when the metals are mixed into a solid, how does the acid reach below a few mm's.  I really don't know how that works with metal alloys and acids. 

On another note, I had read that Cu dissolved in HCl to make a chloride (it is supposed to be usable for printed circuit board leads)  I placed about 200ft of 32-36g wire in HCl and it turned green within a day and then a deep brown.  After 4 months it was back to clearish with some yellow but there was brown powder in the bottom.  I stirred it and it was back to being solid brown.  I have pics of this from start to finish I can post if that would help.

Oh, I think I get what you are saying, Dissolve the Zn and AL with H2SO4 and then do whatever with the remaining Cu.  I was just playing around with some Cu in battery acid and it seems to dissolve slowly (about 1/1000) speed with 10% H2O2).

How could I remove the small bit of dissolved CuSO4 in the mix?

[AWK]

Look at textbook(s) on qualitative inorganic analysis.

[Intanjir]

You can get copper and zinc to plate out of an aqueous solution using electrowinning. Aluminium will stay dissolved.

[RogueRose]

Thank you for the replies!  I was thinking that another option would be the use of a strong NaOH solution which would dissolve the Zn and Al producing Sodium zincate (Na2Zn(OH)4) and Sodium aluminate (NaAlO2), leaving the copper. 

I see that the aluminate is soluble in water and alcohols but am unsure of the zincate and that also leaves the questino as what to do with the two products.  I know a good number of things that can be done with the salts made from acids. 

The reason I suggested this is it's always nice to have a couple options and knowledge but also NaOH (as compared to H2SO4) is much more economic in my current situation by a factor of about 10-20 depending upon quantity needed.   

[AWK]

More correct formula for sodium aluminate is Na[Al(OH)₄].
Look at texbook of qualitative analysis what happens after addition of NH₄Cl to the obtained solution.

[Intanjir]

A zinc aluminate co-precipitate would be a possibility. I know this sort of thing happens when you try to combine a sodium silicate and sodium aluminate solutions.