The Effect of Atomization Method on the Morphology of Spray Dried Particles

Effect of various atomization methods as well as solution concentration on the morphology of MgSO₄ particles produced by spray drying of aqueous solutions of MgSO₄ is investigated. Four types of atomizers are tested: (1) A mesh vibrating nebulizer, which generates low velocity droplets of 0.2 m/s with a size range of 1μm to 7 μm. (2) A splash plate nozzle, which generates droplets with an average velocity of 21 m/s and a size range of 40 μm to 500 μm. (3) An air mist atomizer, which generates droplets with an average velocity of 22 m/s and a size range of 20 μm to 150 μm. (4) A pressure atomizer, which generates droplets with an average velocity of 20 m/s and a size range of 30 μm to 1000 μm. Several types of particle morphologies are identified in this research. For the vibrating mesh nebulizer most of the particles are non-disrupted thick wall shells. For the splash plate and the air mist atomizer most of the particles are deformed spherical shells due to contraction and some are uniformly or non-uniformly disrupted. Higher initial solute concentration thickens the shell wall and prevents the particles to burst. It is found to be hard to obtain fully filled particles even for nearly saturated solutions at room temperature.