PARTICLE CHARACTERIZATION AND DETERMINATION OF ERODIBLE FRACTION OF SURFACE SOIL NEARBY THE OPEN PIT IN MALMBERGET MINE, SWEDEN

Abstract

Wind erosion of soil from exposed areas in mining sites is one of the sources for dust generation. Particle size distribution and mineralogical composition of source soil, erodible fraction of surface soil, moisture, as well as organic matter content are important factors that determine the property of particulate generation process. In this research four soil samples were taken using shovel at different depth from the edge of the pit and the surface area nearby the pit in Malmberget mine in Sweden. Soil samples were analyzed for density, particle size, mineralogical composition, organic matter content, and CaCO3 content. No calcite was detected by Qemscan and consequently, CaCO3 was assumed absent in the soil samples. Moisture contents in the surface samples were too little to prevent soil from wind erosion. All soil samples were mainly composed of albite, quartz, and K felspar. Miner minerals such as mineral 23 (bFe, bCa), as well as grossular, were more abundant within the surface samples while the reverse is true for ilment. It should be mentioned, however, that undersurface samples contained more particles of 100 μm in diameter compared to surface samples. Measured erodible fractions for surface samples were 35.9% and 43.39%. The erodible fraction was calculated for the soil of the studied area but the equations could not be applied because the calculated values were overestimated. The value of soil erodibility index was determined to be 19t/acre which was wind erosion group 7. Since wind erosion group 7 is not a highly intrinsic erodible soil group, the dust problem might also arise from disturbances of soil surface soils by trucks and other construction activities around the open pit.