Geoid - 30-3-2011 at 05:14
I have kilos of crushed ore that contains ~1% very fine cassiterite, ~60% iron oxides Fe2O3, Fe3O4 and FeO-OH and some silica.
I want to extract the cassiterite and am considering dissolving in hydrochloric acid and trying to precipitate the iron or use an alkali fuse/leach
techniques with NaOH to form soluable stannates which could be precipitated and elctrowinned.
Is there someway to exploit the fact that dissolving in HCl will leave a fine, colliodally suspended oxide (tin) in an ionic solution of ferric ions?
The cassiterite is said to be 5 micron and less.
blogfast25 - 30-3-2011 at 06:12
Are you sure that your cassiterite will be present as a colloid? It's true that SnO2 tends to form colloids (I've seen it do so myself - very
annoying) but colloids aren't very stable in highly ionic solutions with trivalent ions like Fe3+ present. So it’s possible that your cassiterite
will not peptise at all.
Dissolving the ore into HCl can be a bit of an oxymoron though: depending on the state of the ore even conc. HCl may not even make a dent in it and
hot conc. H2SO4 may be needed to digest the ore. Or fuse with NaHSO4.
Have you considered extracting the cassiterite by fusing the ore with NaOH or KOH? Considering the very small amounts of Sn in there that might not
make much sense at first glance but SnO2 fused with alkali (even plain soda should work) forms water soluble stannates, leaving the Fe oxides
behind… The Si would huddle with the Sn, of course..
[Edited on 30-3-2011 by blogfast25]