Introduction to the ancient Ying iron smelting model: Displayed here is the ancient Ying Han Dynasty "Heyi" iron smelting site model. "Heyi" was the No. 1 ironmaking workshop under the jurisdiction of Henan County in the Han Dynasty. It was the largest ironmaking workshop in China at that time and could produce 1 ton of iron per day. It was also the first to use coal as fuel and apply preheating blast technology, which represents my country's advanced smelting and casting technology level before 2000 and occupies an important position in the metallurgical history of China and the world.