recovery of Ag from Al/Ag alloy

[Mennig]

Hi, I'm new here, thanks for the assistance.

I have approximately 4000# of aluminum/silver alloy. 96% Al 4%. I wish to recover the Ag in the most economic and enviromentally sound way as possible. Have consider NaOH and Nitric and both are to enviromentally challanging.

I have smelting capabilities available (in an industrial setting) but can't conceive of a way to separate these elements in that way.

Am considering electrolytic separation. I have used this in the past for simple silver refining (sterling) (thumb cell) but with the Al in such a large percentages I don't know how to go about it. Could I use half cells? Cathode being .999 ribbon in silver nitrate solution and the Anode being my alloy ingot? Will silver ions cross the salt bridge? Would I need to use AgNO3 in the annode cell also or would I use AlOH?

[deleted-71588]

Science Buddies experts are here to assist K-12 students in doing Science Fair Projects.

This question sounds like a commercial/industrial question.

[deleted-71296]

1. The most efficient way to separate the silver from the aluminum would be to first dissolve the alloy in nitric acid (50% concentrated HNO3; 50% H20). Do this in a hood because there will be a lot of fumes!!
2. After dissolution, dilute with more water to about 10% HNO3.
3. Add sodium chloride solution, which will precipitate the silver as AgCl.
Al will stay in solution.
4. Filter and dry the AgCl. You might be able to smelt that.
To recover metallic silver, put the alloy solution after Step 2 in an electrolytic cell with two electrodes made of carbon (single cell; no separator) and electrolyze at 2-3 volts dc.
Silver should deposit on the cathode (negative electrode), but the deposit will be loose and tree-like and may drop off the electrode to some extent.
To get a nice smooth adherent deposit, you would have to neutralize the acid to get an ammonia solution, and electrolyze that.
After electrodeposition, scrape the silver off the cathode.