Characterization of fugitive dust emissions from the tailings of a Northern Michigan iron mine

Cleveland Cliffs Incorporated (CCI) manages two independent iron mines in northern Michigan. The mines are unique in that their milling process produces tailings that are generally less then 20 microns in diameter. These tailings are deposited into two basins that are 1200 and 500 hectares in size (Cliffs 1997). These features, coupled with conducive meteorological conditions, can yield excessive fugitive dust emissions. A significant fugitive dust event materialized on November 15, 1996. Wind gusts in excess of 60 km/hr and cool dry conditions produced a dust storm that reduced visibility in the local community to less then 1 meter in some places. Following the November dust episode, CCI began working in conjunction with Michigan Technological University (MTU), the Michigan Department of Environmental Quality (MDEQ), and Barr Engineering to ameliorate future dusting episodes. To control dust emissions, MTU is performing laboratory and field experiments with several crusting agents and several types of vegetative cover. CCI and Barr Engineering are assisting in the application and monitoring of these mitigation options. Experiments to understand the mechanisms that are involved in summer and winter dusting episodes are also being conducted. This paper provides an overview of the problem, characterizes the fugitive dust source, and summarizes the preliminary results of the control strategies comparison.