Particle Breakage in a Scirocco Disperser

Particle breakage during dry dispersion for particle sizing is of concern, yet little work has been carried out on its quantitative analysis. An integrated experimental and CFD modelling work has been carried out to study the breakage of a weak and friable powder in a Scirocco disperser at various nozzle pressures. Spray-dried burkeite powder is used as a model test material. The breakage of particles is analysed using Malvern Mastersizer 2000. The extent of breakage as a function of particle size and impact velocity is obtained by carrying out controlled breakage tests using the single particle impact test device available in our laboratory. The impact velocity of particles in the disperser at various pressures is evaluated by Eulerian–Lagrangian CFD simulation of the air flow in the unit. Particles of different sizes are found to accelerate to different velocities and break to different extents. Particle breakage is noticeable even at the lowest nozzle pressure. A remarkable unification of breakage data may be obtained when the relative change in the surface area for different particle sizes is expressed as a function of the dimensionless breakage propensity group, η, based on the impact velocity in the Scirocco, obtained from the CFD simulation.