Medieval smelting method for mass production of wrought iron. Also known as the mixing method. The structure of the Pudelin furnace is similar to that of a plain furnace, except that there is no lower regenerator.
(See the picture) The long flame formed after the fuel is burned is sent into the furnace, and the pig iron is heated by the reflection of the furnace top. The furnace bottom is built with iron oxide. Due to the excess oxygen in the flame and the large amount of oxygen in the furnace bottom, the pig iron The carbon and phosphorus in it are removed by oxidation.
However, the temperature of the Pudelin furnace is only about 1400°C. After the carbon in the pig iron is removed to a certain extent, the melting point exceeds the furnace temperature and the metal is in a semi-solidified state. Manual stirring is required to continue the smelting.
However, since the furnace bottom and slag contain extremely high 470% iron oxide, the carbon can be removed to a very low level and become wrought iron plate. Then, after repeated forging, the iron oxide slag in the wrought iron is squeezed out, and the material is used.
The Pudelin method was the main production method before the emergence of modern steelmaking. It once reached a considerable scale of production. In the mid-18th century, more than 70,000 kilometers of railways were paved with Pudelin wrought iron in European and American countries.
However, due to the fundamental weaknesses of semi-solid smelting – poor working conditions and poor quality of wrought iron, the Pudelin method was quickly eliminated after the birth of the Bessemer method.