水蒸気-溶融鋼津-溶鉄間の水素平衡について
1964 年 50 巻 6 号 p. 878-887
詳細
1964 年 50 巻 6 号 p. 878-887
In order to improve understanding of the behaviour of hydrogen in the system atmosphere-molten slag-molten steel in a steelmaking furnace, we already reported dissolution of water vapour in molten slags in the previous paper.
In this experiment, as a next step, the form of hydrogen in slag has been determined by infra-red spectra measurements which have been carried out on the ternary and quaternary CaO-Si02-(mono, di, tri-valent metal oxide) systems.
Then, simultaneous equilibria of hydrogen in the system water vapour-molten slag-molten iron have been investigated by equilibrating CaO-Si02 binary slag and pure iron with water vapour.
The results obtained are as follows.
1) Water vapour dissolves into molten slag as a free, hydrogen bonded and a strongly hydrogen bonded hydroxyl, and more than one half of total amount of hydroxyl exists in free form.The existence ratio of each form of hydroxyl to total amount of hydroxyl varies characteristically with different basicities.In the systems CaO-SiO2-MO, the existence ratio of free form becomes greater and those of two other forms become smaller with increasing ion-oxygen attraction force of Mu+.2) Dissolution formula and equilibrium constants of hydrogen equilibria in the system water vapour-molten slag-molten iron are determined as
H2O (g)(O) =2 (OH) K1= (OH) 2/PH2O·(O) logK1=-2, 160/T+8.144
(OH) =H+ (O) K2=H.(O)/(OH) logK2=-4, 800/T-0.835
The hydrogen solubility of slag and iron under PH20 682 mmHg is found to be H 5'5ppm (H) 30'3ppm at 1550°C, H 6.3ppm (H) 33.5ppm at 1600°C
respectively, and these are proportional to the square root of the partial pressure of water vapour.'I hus, CaO-Si02 slag which intervenes between water vapour and molten iron considerably decreases the solubility of hydrogen in iron.
