2018 Volume 58 Issue 12 Pages 2288-2297
To improve the properties of steel, lower sulfur content is required. Therefore, powder blast is often used for desulfurization in secondary refining process, and increasing efficiency is important for desulfurization treatment. As a fundamental research, water model experiment under reduced pressure was carried out and behavior of a particle from penetration to flotation was analyzed. A polypropylene particle (3.2 mm in diameter) was blasted onto the water surface with Ar gas through a single-hole nozzle, and behavior of the particle was recorded by a high-speed camera. According to penetration of the particle, an air column was generated and a bubble remained on the particle after rupture of the air column. The Particle with high velocity before penetration floated to the water surface rapidly even though they penetrated into water deeply as the residual bubble was easily generated. Therefore, increasing particle velocity before penetration does not result in increasing detention time of the particle, and it is suggested that the particle should be blasted by its own velocity without generating the air column to avoid remaining the bubble. In addition, flotation behavior of the particle was analyzed by a kinetic equation. As a result, when the residual bubble was greater than 2 mm in diameter, the apparent resistance coefficient increased with diameter of the residual bubble. This is because that increasing diameter of the residual bubble led to increasing projection cross section area of the particle including the bubble, and because the friction force between liquid and the particle was increased.
