# help needed



## arthur kierski (Jul 8, 2008)

as i am needing help for pgm separation,i am using this thread.
i had 3,82grams of a mix of pgm,to this 3,82 i added hno3-dwater 1:1 and tried to extract the pd---result no pd but the pwder left became 3,17grams--i took this 3,17grams and did the ap process---i was left with 1,37 grams which i asume is rh+silica----them to the ap solution which for me was pt ,i added nh4oh(lous way of extracting pt) --whem i added this nh4oh a golden yellow pwder precipitated and the solution which was redish became green---i filtated the yellow powder and added hcl , boiled until all dissolved and dropped with hidrazine a powder which by other experiments i think is rh--to the green liquid i also added hidrazine and a black powder which i think is pt precipitated---these 2 black powders gave 1,80grams--so i have 1,80grams of a mix +1,37grams (rh +si)=3,17grams---the 1,37 grams i added hf +h2so4 and what will remain is rh----i think that i extracted the rh in 2 stages, but i am not sure---can anyone tell me if my procediment was correct?or where i made a possible mistake ?
by the way this 3,82grams came from 1,20kilos of a citroen vitara honeycomb


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## lazersteve (Jul 8, 2008)

arthur kierski said:


> i had 3,82grams of a mix of pgm,to this 3,82 i added hno3-dwater 1:1 and tried to extract the pd---result no pd but the pwder left became 3,17grams


Art, where did the 0.65 g go. I would be inclined to believe it's in the nitric solution. Assuming you mean the nitric solution tested barren, it indicates the PGM powder was contaminated with a nitric or water soluble compound. If the powder were incinerated or heated in an oxygen environment prior to nitric treatment the Pd likely became oxidized and should be extracted with HCl prior to nitric treatment.



arthur kierski said:


> --i took this 3,17grams and did the ap process---i was left with 1,37 grams which i asume is rh+silica----them to the ap solution which for me was pt ,i added nh4oh(lous way of extracting pt) --whem i added this nh4oh a golden yellow pwder precipitated and the solution which was redish became green



It's odd that 1.8 g dissolved in AP (acid peroxide) and not in nitric. This leads me to believe you meant to say AR (aqua regia). The rest of the reaction sounds straight forward for the results you obtained. 

You can test a small sample of your resulting powders with a drop of water and a drop of stannous to confirm the presence of Pd and Pt. You can dissolve a small sample of the resulting powder in HCl and water and heat to test for Rh if the first test proves negative. The solutions color change sounds odd also for Pt . Red is typically an indication of Pd. Pd solutions will behave just as you mentioned to the ammonium hydroxide and hcl treatment (yellow powder). Hoke mentions this as a cleanup procedure for Pd salts. Pt solution are usually yellowish/orange when dilute and brown when concentrated from my experiences. 



arthur kierski said:


> ---i filtated the yellow powder and added hcl , boiled until all dissolved and dropped with hidrazine a powder which by other experiments i think is rh--to the green liquid i also added hidrazine and a black powder which i think is pt precipitated---these 2 black powders gave 1,80grams--so i have 1,80grams of a mix +1,37grams (rh +si)=3,17grams---the 1,37 grams i added hf +h2so4 and what will remain is rh----i think that i extracted the rh in 2 stages, but i am not sure---can anyone tell me if my procediment was correct?or where i made a possible mistake ?



Something just doesn't sound right about the behavior of the original black powder to the treatments you describe.


Steve


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## arthur kierski (Jul 8, 2008)

steve,i made a real mess----i do not know why the hno3 reduced 3,82 to 3,17 and did not give pd--- i will stay with the idea that the 0,65grams grams is as you told a hno3 soluble compound.----as you said the nitric solution tested barren-----today i did the following ---the 1,37grams with hf+h2so4,became0,52grams----0,52grams +1,80grams =2,32grams
+ar and eliminating nitric 3 times with the addition of hcl--gave a deep red solution---this solution+kcl----gave yellow pt salt(0,78grams of pt---reduced with hydrazine----and to the still red solution i added nh40h---became blue and with hydrazine gave a black powder which with ar gave o,98grams of pd and 0,34 grams of rh -----by the way the ar treatment (2,32grams) left 0,22grams of rh---so the final result was 0,98 pd +0,78pt +0,56rh =2,32grams and a lost of 0,65grams 
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with all the mess , that was the result
---thanks steve for helping me always


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