Prediction of mineral dust properties at mine sites

Abstract

Predicting the properties of dust generated at mine sites is important for understanding the impact of dust dispersal to the surrounding environment. This chapter presents a new approach to predicting the mineralogical properties of the PM2.5 and PM10 dust fractions. A purpose-built dust resuspension machine was fitted with a size selective sampler to collect dust fractions. Dust particles were collected onto a polycarbonate filter, which was analyzed using a scanning electron microscope (SEM). Backscattered electron (BSE) maps of the polycarbonate surface were imaged and processed to determine dust properties. For a given population of particles, the BSE brightness distribution of the 2-5 and 5-10 µm size fractions were quantified. The mineralogical composition of the dust size fractions were inferred by the BSE brightness as biogenic particles and sulfates (30-50), silicates (60-100), iron silicates and oxides (110-190), and sulfides (>200). The method was validated by comparing laboratory-generated dust fractions with those collected from dust monitoring stations at a tailings repository site. Similar dust composition and size fractions were observed for both laboratory and field samples. Consequently, the purpose-built dust resuspension device and associated laboratory procedures allow the prediction of mineralogical properties of dust at mine sites.