酸化ニッケルペレットの還元に及ぼすCaO, MgO添加の影響

抄録

Effects of CaO and MgO as soluble additives in nickel oxide on the reduction of nickel oxide pellet were investigated. The foreign oxides were revealed to give almost the same effects as on the reduction of wustite. The following results were obtained.
(1) CaO causes the reduction rate of nickel oxide to increase with increasing amount of CaO up to the amount in which the reduction rate is maximum, and over this amount the accerelating effect becomes weak gradually.
(2) MgO retards the reduction of nickel oxide pellet as the amount increases.
(3) The temperature dependency of the reduction rate of nickel oxide pellet containing CaO was hardly observed, but that of nickel oxide pellet containing MgO was very significantly compared with that of pure nickel oxide, and the reduction rate in the later period of nickel oxide pellets containing 2.4 mol%MgO was minimum at 1073 K, while that of pure nickel oxide pellets was minimum at 1173 K.
(4) The reduction rates of nickel oxide pellet containing CaO at almost all the reduction temperatures employed in this work and those of pure nickel oxide pellet at 873 and 973 K can be represented by the mixed control equation based on an unreacted core model. On the contrary, the reduction rate of nickel oxide pellet containing MgO can be represented by the oxygen diffusion limiting rate equation through the metallic nickel shell formed on individual nickel oxide particles.