multiple-hearth roaster
Quick Summary
A multiple-hearth roaster is a type of furnace used in metallurgy, specifically in pyrometallurgy, for processes like roasting and calcining. Roasting involves heating ore in the presence of air without melting it, often to convert sulfide ores into oxides. Calcination is the heating of carbonates to oxides.12
The multiple-hearth roaster is a vertical, cylindrical steel shell lined with refractory material. Inside, superimposed hearths hold the roasting material. A central shaft with rabble arms stirs the material and moves it through drop holes to lower hearths. As the material moves downward, it encounters a rising gas stream that facilitates the roasting process. The roasted material, called calcines, is discharged from the bottom hearth. These roasters are versatile and can be used for various processes, including oxidizing, sulfatizing, chloridizing, and volatilizing.1
Ask Britannica AI about this topic
Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.
