Tracking Deposition and Settling Characteristics of Airborne Metallic Particulate

Transport and deposition of metal particles is a source of environmental and public health concern. Understanding how ambient conditions and the properties of the particles interact to influence the dispersal range can provide information on and the possible extent of environmental contamination. Controlled laboratory experiments and modeling were utilized to determine when such particles would deposit. Particle samples containing heavy metals, a Palladium-dominant alloy and a Nickel/Aluminum dominant alloy LANA, were released in a static column, and the vertical displacement was tracked utilizing a Phantom v7.3 camera and a camera lens. Electron microscopy revealed that particles are not spherical and size varied. For Palladium particles the size ranged between 300 and 1000 microns, and the diameter range for the LANA particles was between 3 and 550 microns. LANA particles formed clumps which was not seen in the Palladium particles. The density of the Palladium particles ranged between 4.21 and 11.06 g/cm3 and LANA ranged between 6.72 and 8.12 g/cm3. Particle density and diameter primarily influenced the magnitude of the velocities reached as the particles traveled in a stagnant column of air. Experimental results revealed that settling velocity for particles ranged between 1.95 and 3.07 m/s over a settling distance of 1120 millimeters for Palladium particles and settling velocity for LANA particles ranged between 1.54 and 2.35 m/s over a settling distance of 920 millimeters. Force balance models predicted that experimental data for Palladium particles did not yet reach terminal settling velocity, and LANA particles had reached a terminal settling velocity.