Wind tunnel simulation of environmental controls on fugitive dust emissions from mine tailings

The development of techniques for determining fugitive dust emissions presents numerous challenges and remains the subject of much investigation. Past approaches have included field based monitoring stations and wind tunnel studies, while more recently, highly portable field units (e.g., PI-SWERL) have been added to our toolkit of instruments and methodologies. In the case of the investigation reported herein, a laboratory wind tunnel study was designed to systematically simulate PM10 emissions from mine tailings for a range of surface treatments. Unique challenges were associated with the project in the sense that the proposed mine and tailings did not exist at the time of the investigation, so that it was impossible to work on-site. Only a small amount of slurry from a milled drill core was available to work with, and there were no established test protocols and few experimental precedents to work from. The slurry formed highly cohesive bricks when dried, similar to crusted playas investigated in field experiments. The PM10 emissions demonstrated strong temporal variation with particle supply limitation. A small amount of vertical dust dispersion was observed, with PM10 concentrations decaying exponentially away from the source. The emission rates obtained are similar in magnitude to those obtained in field analogues. The highly controlled experiment allowed for separation and analysis of several physical controls on PM10 emissions from tailings; namely, the study addressed the degree of disturbance, shrinkage and cracking, and the effects of spigotting, particle settling and re-wetting.