Gold smelting flux

[sayf]

Roasting ore concentrates will drive sulfur out and change sulfides into oxides so that oxidized base metals will be easily collected in the slag while smelting.
if i am right so far then ill continue

My first question is : how i know that roasting is done completly? ​

My second question is: can i skip the roasting stage if i am already using an oxidizer in my flux such as potassium nitrate or MnO2 , potassium nitrate will launch huge amount of oxygen that will oxidize the bbase metals during smelting.

My third question is: i see some people adding iron rod to the concentrates while smelting, why is that?
is it to remove the remaining sulfur in the concentrates?

 

[Lino1406]

Roasting alternative - H2O2 20% soak with spontaneous boiling
Iron reduces precious metals and takes sulfur, chlorine, oxygen...

 

[sayf]

Hi lino, thanks for your reply

Can you give me more details please, you mentioned that the needed concentration of the hydrogen peroxide is 20% can you tell me about the quantity of h2o2 needed lets say per kilogram of concentrates.
and what about the time needed for the process, is there an indication if the process is over?

Also what do you mean by iron reduces precious metals and takes sulfur chlorine oxygen...?
Will i get rid of iron this way because i font want it in my aqua regia.

What if the concentrates does not have any iron or have little amounts of iron?

Damn that was alot of question but i need details if possible, thanks alot lino

 

[Lino1406]

1. Use just enough H2O2 solution to cover the ore around (0.5 liter per 1kg). After a while, boiling will start, let it boil and stir few times until end of boiling. Like roasting, it converts sulfides, tellurides etc. to oxides, so "freeing" the precious metals to further processing. Give it another hour
2. Iron, in the hot, replaces precious metals if linked to sulfur, chlorine, oxygen...normally you use it in melting, where it becomes slag (mixed with rest iron)