Complex sentence: In desulfurising pretreatment, a lance is lowered into the molten iron in the ladle and several hundred kilograms of powdered magnesium are added and the sulfur impurities are reduced to magnesium sulfide in a violent exothermic reaction.
Split into simpler sentences: In desulfurising pretreatment, a lance is lowered into the molten iron in the ladle and several hundred kilograms of powdered magnesium are added. Sulfur impurities are reduced to magnesium sulfide in a violent exothermic reaction.