Iron-platinum refining
It depends on the concentration of Pt in your alloy.

If the concentration of Pt is to high the HCl will not or not sufficently attack the alloy.

In this case you could try to melt your alloy with some additional Fe, to lower the Pt concentration and then hit it with HCl again.

You could also try to boil it in HCl to increase the reactivity of the acid (do it in a fumehood or outdoors).