I have been working on different ways to make steel from iron ore. My first steps consisted of learning about the Japanese Kodai tatara. Mike Blue and Randal Graham had been doing this for quite a while before I met them. They had watched Akira Kihara, the murage for the Simane prefecture in Japan, when he came to the States to demonstrate his techniques. My own take on this method of steel making has changed over the last few years. I use the solid state direct reduction method. I start with iron oxide and convert it into metallic iron in a bloomery style furnace. Carbon dissolves into the iron to make steel in a not-so-easy-to-control process.
The furnace is made of bricks casted in molds. Sand, ash, clay and vermiculite are used to make the bricks. The top of the stack is made of refractory blanket coated with furnace cement or a chimney flue tile.
The air is provided by a shop-vac controlled by a rheostat, and the tuyeres are made of simple iron pipe plumbing fittings.
I have tried different types of ore, based on availability.
Either hematite (Fe2O3) or magnetite (Fe3O4) can be effectively reduced to metallic iron in the right conditions.
Charcoal is the fuel of choice and the source of carbon. Mixed with oxygen at the right temperature will form carbon monoxide, which is the reducing agent. Depending on the height of the stack, the time span during which the ore is exposed to the reducing atmosphere in the furnace, the temperature and other factors, the end result will be reduction of the iron oxide to metallic iron and absorption of carbon. The usual result of this type of furnace is a mixture of cast iron, steel, and wrought iron combined in a non-homogeneous mass called "the bloom."
The quality of the slag and the atmosphere in the hearth of the furnace will be greatly responsible for the final carbon content in the bloom.
This is a video of the process.