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Why could ancient iron furnaces produce a solid bloom instead of liquid iron?

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How iron is turned into steel — iron processing Iron ore is one of the most abundant elements on Earth, and one of its primary uses is in the production of steel. When combined with carbon, iron changes character completely and becomes the alloy steel.

Ancient iron furnaces produced a solid bloom rather than liquid iron because they were incapable of reaching the high temperatures required to melt the metal.12

The melting point of pure iron is approximately 1,540 °C (2,800 °F), whereas primitive furnaces—such as bowl or shaft furnaces—could typically only reach temperatures up to about 1,150–1,200 °C (2,100–2,200 °F). Because the iron could not reach a liquid state, the chemical reduction of the iron ore resulted in a spongy, solid mass of pasty metal globules intermingled with semiliquid slag and pieces of charcoal.231

This product, known as a bloom, required extensive post-processing. To create usable wrought iron, smiths had to repeatedly reheat the bloom and hammer it while hot to expel the entrapped slag and consolidate the metal.123