Zinc Blende : one example of ore extraction.?

Question

Zinc Sulphide + Oxygen --> Zinc Oxide + Sulphur Dioxide

2ZnS (s) + 3O2 (g) --> 2ZnO (s) + 2SO2 (g)

Then, the oxide is reduced by using Carbon Monoxide:

Zinc Oxide + Carbon Monoxide --> Zinc + Carbon Dioxide

ZnO (s) + CO (g) --> Zn (s) + CO2 (g)

The final mixture contains Zinc and a slag of impurities.

Question: What is the slag of impurities?

Note: It can’t be CO2 or CO, because it’s in gas form.

I’m run out of idea, please help me!

Answer 1

Zinc Blende  is not purely zinc sulphide.It contains other inorganic impurities mainly cations like Ca & Mg and anions like silicates,aluminates & phosphates coming from clay and sand.at the end of the process these cations and anions combine to form a mud like material insoluble in molten metal called as slag.metallurgy of almost all the metals produces slag.