Complex sentence: The greatest achievement was the scientific discovery of a process for obtaining ferromanganese in a smelting furnace, which brought KID a gold medal at the World Exhibition in Vienna in 1873, and worldwide fame.
Split into simpler sentences: The greatest achievement of KID was the scientific discovery of a process for obtaining ferromanganese in a smelting furnace. This innovation brought KID a gold medal at the World Exhibition in Vienna in 1873, and worldwide fame.