Diffuse Emissions of Particles from Iron Ore Piles by Wind Erosion

Abstract

Industrial air pollution from point and nonpoint sources of steel complexes has drawn increasingly more public attention in the past decades. Previous research efforts have been more concentrated on point sources of particulate emissions from these complexes. However, wind-induced particulate emissions from iron ore storage piles not only result in ambient air pollution but also increase economic adverse effects to the industry by loss of process raw materials. Experiments were conducted to assess the impact of wind speed and humidity on particulate emission rates from iron ore storage piles. A wind-generating system and specific iron ore, experimental piles (L:W:H of 30:11.5:5 cm) were constructed to evaluate emission rates at four different wind velocities (4.3, 5, 7, and 11 m s À1 ). Optical and electron microscopes were used for determining size distribution of particles at various distances from emission source. Moreover, the decrease in emission rate was evaluated by changing the percentage of pile surface water content at the maximum speed. Finally, experimental results were compared with classic erosion equations and common parameters such as shearing velocity. Results indicated emission factors of 478, 1,527, 2,315, and 4,409 g m À2 for 4.3, 5, 7, and 11 m s À1 wind speeds, respectively. Pile surface moisture content variations indicated a decrease of 47%-77% in wind-induced particulate emissions for pile surface water content of 2% and 10%, respectively. However, inherent differences between natural winds with continued exerted force and experimental conditions of produced wind were attributed to relatively shorter distance transport of particulates in this study.

Dust Emission from Gobi under Different Dust Content Conditions: A Wind Tunnel Study atop the Mogao Grottoes

“…Soil moisture can affect the adhesion between soil particles and consequently the threshold friction velocity of soil particles. The moisture in the surface material produces adhesive forces between the particles as well as capillary forces through capillary action, which increase the adhesion forces between the particles, requiring a greater wind speed for levitating the particles [19].…”