Converting (metallurgy)

Converting is a type of metallurgical smelting that includes several processes; the most commercially important form is the treatment of molten metal sulfides to produce crude metal and slag, as in the case of copper and nickel converting.

A now-uncommon form is batch treatment of pig iron to produce steel by the Bessemer process.

Molten sulfide material, referred to as matte, is poured through the hood into the converter during the operation of loading.

This high temperature roasting allows oxygen in the air to replace sulfide compounds in the minerals.

Unless carefully captured, these oxidized sulfur compounds such as sulfur trioxide leave the converter as a noxious acidic vapor, along with other dangerous volatile elements such as arsenic trioxide.