Assessing mineral dust properties using passive dust samplers and scanning electron microscopy

This study presents a novel method to characterize dust particles using a passive dust sampler (PDS). Six different PDS were deployed around six different metal mine sites (Tasmania, Australia) and left in the field for 1 month. Dust particles were analyzed directly on the PDS using a Field Emission Scanning Electron Microscope. Backscattered electron (BSE) images were collected with a resolution of 0.5 µm per pixel and used to characterize the size and composition of dust particles. Those particles >2 µm in diameter were classified according to the range of BSE brightness values, which correspond to mineralogical compositions. Particles were grouped according to BSE brightness and categorized as organic particles, silicates, Fe silicates and oxides, and sulfides. Dust sources with unique particle size:composition relationships were identified at particular mine site domains (e.g. rock crusher, concentrator plant, tailings dam). The documented method can be used to monitor the dispersal of mineral dust and provide information on the mineralogical composition of particle size fractions relevant to occupational health risks at metalliferous mine sites.