urea in pgm solutions

[arthur kierski]

dear members---i heard somewehre that platinum salt will not fully precipitate with amonium cloride or with iron powder whem one uses urea


to kill the nitric acid--is this true?pla tinum remains in solution!!!!

waiting for replies--thanks Arthur Kierski

 

[lazersteve]

Arthur,

Platinum and Palladium won't fully precipitate even if Urea is not used. Some will always remain in solution even when using ammonium chloride when no nitric is present. The remaining Pt solution should be added to your stock pot to be concentrated and precipitated later. I keep a separate stock pot for Pt and Pd bearing solutions which have previously been precipitated. After I fill the stock pot, I concentrate it and perform another precipitation.

I never use Urea. I evaporate my AR solutions and add HCl to convert the nitrates into chlorides before precipitation. This takes about three or four evaporations to completely remove the nitrates.

Hoke suggests adding zinc to the stock pot and treating the precipitates with nitric followed by AR to start the process over again. She also recommends evaporation to remove the nitric.

Steve

 

[arthur kierski]

Steve,thank you for the quick reply---i sometimes use urea to have a rapid result---that is wrong i know---evaporation to transform the solution in chlorides is the best way---thank you very much to remind me.
your trully Arthur Kierski