溶鉄の脱窒素速度について

抄録

The rate of nitrogen removal from liquid iron and iron alloys containing oxygen, sulphur, silicon, carbon, nickel, and chromium, respectively, was studied at 1600℃ using argon as a carrier gas. The results obtained are as follows:

1. The reaction of nitrogen removal is of the second-order, and it is considered that the chemical reaction on the surface of the liquid iron is the rate-determining step. The rate of the reaction, 2N (in liquid iron) ↔ N₂(gas), is expressed by the following equation:

−d [%N] ⁄ dt = A ⁄ V k₂′ [%N]²

where, A and V are the surface area and the volume of liquid iron.

2. The activation energy of the nitrogen removal reaction is 35.2 K cal.

3. The surface active elements decrease the rate markedly, and the effects of other alloying elements on the rate depend on the effect of the activity of nitrogen in the liquid iron. A mechanism of nitrogen removal from liquid iron is proposed to describe the rate of reaction quantitatively by considering the effect of the absorption of the surface active elements. The apparent rate constant, k₂′ is expressesed as follows at 1600℃:

k₂′ = 0.974 f ²_N (1 ⁄ 1 + 28.4 [%O] + 5.34 [%S])²

where f_N is the activity coefficient of nitrogen in liquid iron.