Public defence in civil engineering, Marjo Sitkiä, M.Sc.
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Dust emissions from aggregate and natural stone quarrying remain in the open pit area
The dissertation investigated the dispersion of dust in hard rock aggregate and natural stone quarries by measuring and modelling in order to assess the environmental effects of crushing and drilling dust. The aim of the study was to determine the extent of dust dispersion and find out the critical factors affecting it. In addition, a commercial modelling program was tested to find out the usability of short-term modelling results. Dust was measured in eight aggregate and two natural stone quarries. According to the measurements, crushing and drilling mainly produce coarse-grained dust, which settles near the dust source. According to the study, the most critical factors affecting dust concentration and spread are wind direction, seasonal climate conditions, number of crushing units and drill capacity. The dust concentration increases with the increase in the number of crushing units and the capacity of the drill. Dust concentrations measured in winter were significantly higher than in summer. This is due to the ground inversion during winter, which prevents the dust from spreading into the larger air mass and instead traps the dust near the ground surface. The dust from the quarrying operations spreads to a distance of a few hundred meters. The background concentration is reached at a distance of 100 m from the drilling and at a distance of 350 m from the crushing with two units and at a distance of about 750 m from the crushing with three units. The modelling program performed well when modelling dust from crushing during the summertime. However, the modelling was not able to react sufficiently to the ground inversion during winter and the modelled crushing dust concentrations were about 5% of the measured ones. The results of the dissertation can be used in evaluating the dust emissions of hard rock aggregate and natural stone quarries similar to the ones studied.
Opponent: Professor, PhD. Olli Sippula, University of Eastern Finland
Custos: Professor Mikael Rinne, Aalto University School of Engineering, Department of Civil Engineering
Contact information of the doctoral student: Marjo Sitkiä, marjo.sitkia@gmail.com, +358440660248
The public defence will be organised on campus (auditorium R2, Rakentajanaukio 4) and it can also be followed via Zoom.
The thesis is publicly displayed 10 days before the defence in the publication archive Aaltodoc of Aalto University.