The main raw material for steelmaking is iron ore. But just like coal, iron ore cannot be used directly in the blast furnace for chemical and physical reasons. Therefore, the iron ore is first converted into sinter. Sinter traditionally represents 90% of the blast furnace charge. The remainder of the charge consists of pellets and calibrated iron ore.

The grate belt is a closed chain of grate carriages positioned against each other. The spread layer is ignited at the top using burners. As the grate belt moves, the flue gases are extracted through exhaust hoods beneath the grate belt. In other words, the mixture is baked from top to bottom. At the end of the sinter belt, the sintered, hot ore cake falls onto a crushing deck, where it is broken and cooled.