Dust controls at the coarse ore storage facility, Oyu Tolgoi, Mongolia

Abstract

The coarse ore storage (COS) facility is repeatedly identified by Oyu Tolgoi as a major source of dust that presented a significant risk to worker health and the environment. Dust monitoring and observations conducted since 2013 demonstrated high concentrations of airborne particulate that were likely to be exceeding air quality standards. Dust generation at the COS occurred from the discharge to the covered stockpile and resulted in fine particulate depositing on the ground surface surrounding the COS. A foam dust suppression system was added to the COS feed in November 2014, with observed and measured reduction in dust emissions. An analysis of dust-monitoring data indicates some reduction in airborne particulate as a result of the foam dust suppressant addition. However, the measured reduction is not as significant as is suggested from visual observation of the COS. Additionally, dust curtains installed in 2019 continue to manage dust at the COS facility. Moreover, we implement some operational mitigations at the facility, including area cleaning, watering, and keeping the COS stockpile to at least 70% capacity to minimise drop-down distances, thereby decreasing dust generation. The dust-monitoring dataset demonstrates the substantial positive impact the installation of dust curtains, and other mitigations, have achieved.