What did the ancients use to melt iron ore?

You can't melt iron at first. But in the spring and autumn period, the ore can be melted, and crucible steelmaking should be delayed.

The original ironmaking furnace was transformed from the stone pile ironmaking method. Dig a hole in the soil and pile it up with stones around it. This is called a ground furnace. Iron ore and charcoal are burned layer by layer in the ground furnace by natural wind, and the iron oxide in iron ore is reduced to iron by carbon monoxide produced by incomplete combustion of charcoal, and the iron block is taken out after cooling. This method of ironmaking is called block ironmaking. The furnace temperature is about 1000℃, which is far from the melting point of pure iron (1534℃).

Yangcheng Cast Iron Smelting Site in Dengfeng, Henan Province began in the early Warring States Period, flourished in the late Warring States Period and continued after the Han Dynasty. The site covers an area of 230,000 square meters, with an excavation area of 400 square meters. Unearthed cultural relics include molten iron slag, blast pipe slag, molds, molds, ironware, fan drying kiln, annealing decarbonization furnace, etc. There are two kinds of furnace wall residues: single material and composite material. The single material furnace wall is composed of multiple materials and multiple layers. The layers of the compound furnace are: fine sand furnace lining layer, roving furnace ring layer, grass mud layer, mud or sandy furnace brick layer and grass mud furnace surface layer from inside to outside. The structure of the furnace consists of furnace mouth, furnace belly, furnace hearth and furnace seat from top to bottom. Debris was found everywhere. From the analysis of the unearthed furnace remains, it can be seen that the shape of the iron melting furnace in the early Warring States period inherited the shape of the copper melting furnace at that time. However, due to the high temperature of molten iron, a series of improvements have been made to the thickness, material and structure of the furnace wall.