using aluminum instead of copper

[smj]

I would like to know if it’s ok to cement values (Pd, Ag) from spent NH03 solution using aluminum instead of copper.
I know that the aluminum will drag down more contaminants but can’t that be cleaned up with the use of hcl?

 

[etack]

I believe that nitric does not react with Al.

Eric

 

[samuel-a]

I believe that nitric does not react with Al.

Eric

Yup. That is correct.

 

[smj]

I drop the silver using hcl = agcl. Now I'm sitting with a dilute AR solution, the al will now react with the solution. I just wanted too know if its a bad idea doing this as is drops other metals as well. The up side in doing this is the reaction is much faster than using copper.

 

[Geo]

using a more reactive metal to cement will cement all the less reactive metals in the solution. besides, if you want to refine, you need to know how to get the gold from solution without cementing it out.

 

[smj]

gold is not what i'm focusing on. this is waste solutions, I'm dropping agcl and recovering pd afterwards. I just wanted to know if its ok to use al instead of cu.

 

[Geo]

ahh, you should check Hoke's book on creating and maintaining a stockpot. use copper if values are present, if you use anything more reactive, it will cement the copper out of solution too. so you really havent done anything but made contaminated copper. cement using copper first to get your values and then you can use steel or zinc or aluminum to get the copper out.

 

[smj]

ok, thanks man. the thing isi used cu to drop pm's but it took a while, maybe there was still some free nitric in solution. So it consumed the cu before it could drop the pm's. Why is it that pm's sticks to cu bar ? i constantly need to scrape it for exposure, it can be very time consuming.

 

[smj]

I want to keep as much Pd separate from Ag, can I use a Ag bar to drop Pd before I drop Ag with Cu ?

 

[Geo]

you can add sodium chloride (table salt) to precipitate the silver first as silver chloride.

 

[smj]

I'm busy converting my AgCl, lye/corn siryp method and takes time doing this. double rinsing, i would love to drop Ag using copper without dropping Pd. Will the silver bar drop Pd before using copper ? I'll see what happens on my next batch.

Thanks for the information

 

[lazersteve]

Copper cements all metals below it in the activity series chart. You can find a copy of the chart on my website (link below) in the documents section or in many places on the internet. This chart is a fundamental part of precious metals recovery and refining processes. It is well worth spending some time to learn it and understand how the chart relates to actual reactions.

Steve

 

[goldenchild]

smj,

To answer your question. No. You can't drop silver and Pd separately using copper in a mixed solution. You would do best using a silver cell to separate the two. Do your research on the electromotive series and then the silver cell in that order. Good Luck.