Complex sentence: In a single stage system the iron ore is both reduced and melted in the same container while in a two stage process, like Corex, the ore is reduced in one shaft and melted and purified in another.
Split into simpler sentences: In a single stage system the iron ore is both reduced and melted in the same container. Meanwhile in a two stage process, like Corex, the ore is reduced in one shaft and melted and purified in another.