How to convert Antimony Sulfate to Sb2O3???

Panthera Leo

Hi,

I have got some Antimony Sulfate and would like to convert it to Sb2O3 to be used as a refining & reducing agent in glass melt. But I am not sure if using the sulfate as such will decompose in the oxide at high temperatures (around 1200 celcius)... Any help will be highly appreciated.

Is there any other reducing agent you could recommend?

Thanks.

AGNuke

Heating Antimony Sulphate will likely decompose it to Antimony (III) Oxide and Sulphur Trioxide.

chemisttree

It is supposed to hydrolyze in dilute water to the oxide. Sounds messy to me. Why don't you just get some antimony trioxide instead?

lightarrow

Why reducing? In the sulfate, Sb is in which oxidation state?
Anyway, if the sulfate is water soluble and gives Sb ions and SO4^2- ions, you could add Ca(OH)₂ or, better, Ba(OH)₂ (more soluble) and calcium or barium sulfate precipitates giving Sb oxide or hydroxide (or antimonic acid?) and in case you dry the last by heat.

chemisttree

Antimony oxide acts as a reducing agent towards manganese and chromium oxides in glassmaking.

Panthera Leo

Thanks for the instructions... sounds very interesting indeed...

But I am really scared of touching Sb in aqueous state. I guess I will just add a 0.5% of glass batch the Sb sulfate and see what happens :D

Panthera Leo

You're 100% correct :)

without Sb2O3 it's almost impossible to create deep/pure green colors (from Cr2O3) generally because sodium oxide and chromium oxide react to form sodium chromate which gives the glass a yellowish tint.

If there's a tiny amount of PbO in the batch, lead chromate will form making the glass brownish orange instead of green !

Both cases can be avoided with the addition of Sb2O3...

Panthera Leo

I wish, I could ... I have searched every single chemical shop in town but non of them is offering the oxide for sale!!! all I could find was the sulfate.