高純度鉄（玉鋼）の生成に関するプロセス工学的アプローチ

抄録

Tamahagane is compared to the lance metal with multicolor after extremely low temperature blowing in a test converter using a multifaceted process engineering approach. The following conclusions were reached:

(1) The golden portion of tamahagane consists of an oxide film approximately 20 nm thick, which is composed of three layers. This multilayered oxide film gives tamahagane its “gorgeous” color.

(2) Tamahagane, a high-purity iron, is produced through a metallurgical reaction network consisting of three reactions: a hydrogen production reaction due to the decomposition of moisture in the blast, a reverse water-gas shift reaction, and a carburization reaction due to aging (long-term refining).

(3) The temperature at which tamahagane is formed through this metallurgical reaction network is around the iron point (720°C) of the intersection point between Fe–FeO equilibrium and Boudouard equilibrium and the eutectoid temperature of the iron-carbon system (A1 point: 723°C).

(4) In the case of a weight absolute humidity of 0.0055 (kg-H₂O/kg-dry air) at a base temperature of 10°C, and 0.0085 after adiabatic humidification (compression ratio of 1.1), the carburization time for an average carbon content of iron (total weight of 3 ton) is approximately 10.5 to 16.0 hours.

(5) Humidity of environments where Tamahagane is made is another important factor as well as charcoal reactivity and TiO₂ content in iron sands.