magnesium or zinc?

To recuperate Rh from spent rh plating solution by, cementation---which metals is better to use ,zn,or mg?in what form? powder or metalic pieces?
thanks in advance for yours ideas and coments
Arthur Kierski

arthur kierski said:

To recuperate Rh from spent rh plating solution by, cementation---which metals is better to use ,zn,or mg?in what form? powder or metalic pieces?
thanks in advance for yours ideas and coments
Arthur Kierski

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Hi,Arthur,

I have never gone through the entire procedure for the refining of Rhodium from plating solutions. However, I once worked for the largest supplier (at that time) of PM plating solutions in the world. When I started with them in Los Angeles, before their refinery was built, we just had an office where we prepared PM scrap for shipment to the Main office and refinery in New Jersey. To eliminate the shipping of solutions, we used 325 mesh "zinc dust" to drop the gold out of the gold solutions, but for the rhodium solutions, we used magnesium powder. I don't know the reason why. I do know that the refinery was run by very knowledgeable people, so I would say that there was a very good reason for using it. Maybe the drops were more complete or maybe the separation of the Rh from the Mg was simpler, than with Zn. I just don't know.

thanks Goldsilverpro,i asked about zn,or mg,because i find some dificulties in eliminating excess zinc powder after the precipitation of Rh from the spent plating solution----the zinc follows the semi pure Rh sponge--- When i produce a new rhsulfate plating solution,i discovered ,zinc impurities in the bath----and had to clean the bath using potassium ferrocianide to precipitate this zin out---I obtained some magnessium thin metals leafs,and will try to cement the rhodium with it---That was the reason why i asked for help in my thread==After i do the cementation wit mg,i will tell you the results and hope that it works
Regards,i after 5years (retired) decided to come back and will sometimes need your help---i learned a lot with your know-how and experience
Arthur Kierski

Lead is a contaminant metal in zinc. Not in magnesium. Also magnesium is faster, and not much more expensive. My experience with Rh is very limited to non-existent.

thanks Cucho gold for replying---yes,the lead ion is eliminated together with zinc,whem using potassium ferrocyanide ,by filtration with special filter paper(stays in the filter)---qualitative filter----