In order to understand the alkali elution behavior of steelmaking slag under continuous flow, a kinetic study was carried out by continuous stirred tank reactor (CSTR). Tap water and seawater were used for measurements of circumferential velocity and temporal change in pH, respectively. Liquid was fed into the vessel and flowed constantly during the impeller rotation operation in the vessel. The effect of the various operating factors such as vessel inner diameter, slag size, slag composition, ratio of liquid volume to mass of slag, seawater feed rate, impeller height from the slag, impeller rotation speed etc. were investigated.
The circumferential velocity in the vessel was not affected by seawater feed rate but by the impeller rotation speed. The alkali elution rate increased with the increase in the circumferential velocity. The alkali elution rate was not influenced by the ratio of liquid volume to mass of slag and impeller height from the slag surface. The alkali elution rate decreased with the decrease in diameter of slag particle below 0.01 m due to the insufficient penetration of seawater between slag particles. The alkali elution rate increased with the increase in seawater feed rate at the same circumferential velocity. The non-dimensional correlation equation of alkali elution rate was shown by Sh = 8.26×10⁻⁴Re_p^0.62 (Nτ)^−0.37 where Sh: Sherwood number, Re_p: Particle Reynolds number and (Nτ): the product of impeller rotation speed and residence time.