magnetic powder containing rh and iron

[arthur kierski]

i have this powder and after much work---hcl, ar (for 2hours),i finally (i thought) got the rh free of iron-----the powder is not magnetic anymore------after fusing this rh with nahso4 and making a rhsulfate solution(green colour instead of redish yellow),i suspected that the solution contained iron---i added to this solution potassium ferro-cianide and imediatelly formed a deep blue ,prussian blue----indicative that the initial powder still contained iron----
question:all iron is magnetised? or you can have an iron powder that it does not get atracted to magnets?

question2:how one can eliminate iron from an fe-rh powder chemically?
thanks for any reply and or advise
Arthur

 

[butcher]

I do not have much experience with rhodium, so take this into account in my suggestion.

Iron can form oxides that are not magnetic; it can also form oxides that acids will not easily dissolve.

I would try getting the iron and rhodium into solution as sulfate, making sure the solution was acidic, using a metal to cement the rhodium, that will replace the Rhodium from solution, these cemented rhodium metals gaining electrons would be converted an elemental metals state.

Trouble here is using zinc or a metal higher than iron in the reactivity series could cement iron from solution.
Using iron or copper metal may work better to cement the rhodium from solution.

Here I would try to get rid of the sulfates from these powders, (because roasting the Rhodium as a sulfate would make it water soluble again), to do this I would wash the powders in a solution of sodium hydroxide, hoping to be able to wash out the soluble sodium bisulfate formed with hot water washes from these metal powders, then dry and incinerate them, and then removing the base metal with an acid that would not put the elemental Rhodium powder back into solution.

Lou, Steve, anybody do you have any better idea's?

 

[HAuCl4]

If all metals are in solution, you can recover all PGMs using sodium sulfide or (not recommended poisonous hydrogen sulfide).

All PGMs are paramagnetic, so they will be more or less attracted to a strong magnet. Are you sure of what you have?.

 

[arthur kierski]

Butcher-----i do almost everything that you sugested in your reply to me----i cement the rh sulphate to elemental rh with iron,do the washings to eliminate all ironsulphate imregnated in the cemented rh powder---i kind of disagree with you when you mentioned(if i understood well or misanderstood) that the cementation with iron or copper will form rh sulphate powder---by my understanding it will form elemental rh , or any other elemental precious metal if present-
Haucl4,i am sure that i am dealing with rhodium----i do pass all my powdered precious metals thru magnets and rarely they show magnetic properties----with nickel and strong magnets, always the ni powder stays in the magnet---
as i said ,and it works---is potassium ferro cianide ---it forms prussian blue ,where the iron interchanges with the potassium and after filtration is eliminated-----
my original question was how to eliminate the iron---and the other question,was if all iron oxides were magnetic(Butcher answered)-----h2s or nasulfide forms iron sulfide which i think is insoluble and will not be eliminated from the rh -iron powder -----
regards to all and thanks
Arthur

 

[butcher]

"I would try getting the iron and rhodium into solution as sulfate, making sure the solution was acidic, using a metal to cement the rhodium, that will replace the Rhodium from solution, these cemented rhodium metals gaining electrons would be converted an elemental metals state."

What I was trying to explain is these cemented powders you could have sulfuric acid or base metal sulfates (from the solution or from drag down) mixed in with the cemented elemental rhodium metal powders.

Leaving these sulfates or sulfuric acid in with the elemental cemented rhodium powders when you incinerate them, could make the Rhodium metal back into a water soluble sulfate again after the roast.

This hydroxide wash, was just a precaution, just in case.

Just in case any remaining base metal sulfates, or sulfuric acid, were involved (it would be like fusing our Rhodium in bi sulfate all over again).

This is why I would wash them with hydroxide to try and remove sulfates as water soluble sodium sulfate, and rinsing well before roasting the finely divided rhodium elemental powders.

I do not know if I am explaining this well.

 

[arthur kierski]

Butcher,thanks once again-----this last thread explained very well and cleared my mind----
Today, i have another batch of rh-iron powder ,and will follow your advices for eliminating the iron---i need pure rh because with it,i make rh plating solutions and sell it for a good price-----130 dollars a gram,instead of todays price of 40 dollars a gram of rh-----
any problems , i will (as always) ask for your advice and help
thanks and regards
Arthur

 

[HAuCl4]

Iron sulfide + HCl gives H2S and the iron stays as a soluble chloride . The H2S which will reduce any PGMs to sulfides...

Good old cupellation with an added gold collector will work to rid of base metals. More cumbersome for small batches imho.

 

[butcher]

HAuCl4, at this point wouldn't it be iron sulfates not sulfides?

The melting with a collector and getting iron into the slag sounds like a good idea.

The trouble I see with the iron here, the iron oxides or hydroxides can be insoluble in acids, and sulfuric which is normally good to dissolve iron can possibly put some of the fine rhodium powders into solution, although not easily.

 

[Mgnaing]

i have this powder and after much work---hcl, ar (for 2hours),i finally (i thought) got the rh free of iron-----the powder is not magnetic anymore------after fusing this rh with nahso4 and making a rhsulfate solution(green colour instead of redish yellow),i suspected that the solution contained iron---i added to this solution potassium ferro-cianide and imediatelly formed a deep blue ,prussian blue----indicative that the initial powder still contained iron----
question:all iron is magnetised? or you can have an iron powder that it does not get atracted to magnets?

question2:how one can eliminate iron from an fe-rh powder chemically?
thanks for any reply and or advise
Arthur

Place this complex powder at concentracted nitric acid for two or more times till brownish fumes stop....this indicate iron dissolve completely ...and then fuse with sodium hydrogen sulphate.....

 

[arthur kierski]

thanks Magnain,for your great sugestion----
regards,
Arthur