What did Africans do to iron ore during the Iron Age in order to make it possible to create iron tools and weapons?

During the Iron Age the people of Africa used iron ores to create weapons and various tools for irrigation. They put the iron ores in blast furnaces to remove any oxygen that was present in the ore. They also used the blast furnace to remove as much impurities as possible. The tools were also fabricated to improve the longevity of the weapons and tools manufactured. The iron workers were so skilled in their work that they used to travel with the armies for creating any kind of iron weapons whenever required.