[Hunter2]

I think if you would use Hydrochloric acid instead you will optain the silver directly. the aluminium gets disolved, the silver will remain. only filtration and good washing is enough. If you have an oven you can melt the silver and make barran or coins.

[Enthalpy]

My two cents worth...

Aluminium has some moderate value as a metal, but zero as an oxide or hydroxide, since the market value of aluminium metal is essentially the electricity needed to reduce it. So aluminium recovery would make sense only if you keep it metallic all the way, as a first guess.

Aluminium electrolytic refining is never done in a watery solution, because Al oxidizes immediately. The industrial process uses molten aluminium salt, chosen for low melting point AND for density lower than the metal, which sinks and stays protected from the atmosphere.

In radio applications, I had expected silver to cover the mechanical metal and provide a good conductive outer layer, where the Kelvin effect concentrates the current. Or did I get it wrongly? This changes radically the question.

With a furnace good enough you might distillate your alloy: Ag boils at 2162°C, Al at 2519°C, at 1 atm - lower pressure may help. Cleaner!

Could you sell the alloy to other people having the same need? Changing a wire diameter is easier than separating an alloy!

At least one mechanical alloy (Weldalite, used for rocket tanks) contains a bit of Ag, so your 4%Ag needs only dilution with Al, Cu etc. Sell it to the provider of Weldalite.