Separating iron from gold powder

Hello Everyone: I have some 24k gold powder which has been slightly
contaminated with small particles of iron. I need gold powder to be
contaminant free so that it can be used in a powder form. I tried to
separate iron from gold powder by putting into a sulfuric acid
diluted with water and let it simmer for about an hour. It didn’t
work. Same thing worked partially on silver with similar situation. I
would be grateful if anyone can help me solve this problem.

Yuvak Tuladhar

If I were you, I'd try a magnet. Get the strongest magnet  you can

This is exactly the method I would use BUT I would put the magnet in
a small polythene bag. This keeps the magnet and the iron away from
each other so that you don’t have to spend hours trying to remove the
irn dust from the magnet. When you have done, you simply take the
magnet out of the bag and the iron dust falls away.

Best wishes,

Ian W. Wright
Sheffield, UK

The magnet in plastic bag will certainly work, but I’m puzzled. You
say you tried dissolving the iron away using sulphuric acid but it
didn’t work. I wonder why that was … it should have worked just
fine. Did you have very dilute acid? Actually pretty much any acid
should dissolve the iron and leave the gold, especially if used hot,
but don’t mix nitric and hydrochloric acids as that constitutes “aqua
regia” which will attack the gold. The only downside to using a
magnet is that a very small amount of gold may adhere (just by
stickiness) to the iron particles.

Kevin (NW England, UK)