Inside a blast furnace
The steel that shapes our modern cities starts from glowing metal made in these massive furnaces
How do the large buildings we see around the modern world stay up? They have skeletons of steel that are strong enough to help support other heavy materials like concrete. That’s why steel is one of the world’s most important products – and so the blast furnaces that make it are very important too. Blast furnaces make very hot, liquid pig iron. In 2016 up to 900 blast furnaces made and melted over a billion tonnes of this iron, which soon became steel, worldwide. Each one makes up to 12,000 tonnes of molten pig iron per day, running around 19 days out of 20. A few extra chemical steps make pig iron into steel.