What pollutants would be emitted from incinerating rock or road salt at 2800 degrees Fahrenheit?

Question

Road salt on steel that will be put into a foundry oven.

Answer 1

Rock salt alone: probably none. The safety data sheet (ref. 1) indicates no decomposition at temperatures high enough to melt the salt, and the chief contaminant in rock salt is a type of clay ("marl").
When heated with steel, there may be a chemical reaction, either with the iron or the alloying ingredients. Molten salt is electrically conductive (ref. 2) which suggests a possibility that a battery might be formed from it and the conductive metals. Ref. 3 says the hot salt will react with air. I would try this on a very small scale first unless you can find more authoritative information.
It is not clear whether the oven heating will remove the salt, which I assume is the intention, but the steel and salt will have different densities which should help in separating them.