Effect of particle velocity on penetration and flotation behavior

Abstract

For improvement of property of steel, lower sulfur concentration is required. Therefore, improvement of desulfurization efficiency is important at desulfurization treatment in the secondary refining process. Powder blasting is often operated for desulfurization in RH process. In this study, effects of velocity of a particle on penetration and flotation behavior were examined by water model experiment under the reduced pressure. A poly-propylene particle was blasted onto water surface with Ar gas through a single-hole nozzle, and particle behavior during penetration into water and flotation to water surface was recorded by a high-speed camera. According to penetration of a particle, an air column was generated and a residual bubble was remained on the particle after rupture of the air column. In case that particle velocity before penetration was low, detention time of a particle increases with increasing of maximum penetration depth. Besides, in case that particle velocity before penetration was high, detention time did not increase so much with increasing of maximum penetration depth because diameter of residual bubble was larger than 2 mm and buoyancy became large. Therefore, increasing particle velocity before penetration does not archive increasing detention time of the particle. To avoid generating residual bubble, a particle should be penetrated with the velocity that an air column is not generated. In addition, flotation behavior of a particle was analyzed by kinetic equation. As a result, in case that diameter of residual bubble is larger than 2 mm, apparent resistance coefficient increases with diameter of a residual bubble.