Geotechnical and Mineralogical Characterization of Hydrocyclone-classified Iron Ore Tailings: Implications for Storage Facility Stability

This study investigates the geotechnical and mineralogical properties of iron ore tailings (IOT) samples—comprised of feed, hydrocyclone overflow, and underflow streams—collected from the Marampa Mines Limited (MML) Tailings Storage Facility (TSF). The primary objective was to quantify how hydrocyclone classification fundamentally alters the physical and mechanical behavior of segregated tailings for structural applications. Laboratory investigations, conducted in accordance with ASTM standards, included specific gravity, particle size distribution, Atterberg limits, one-dimensional consolidation, and consolidated-drained (CD) triaxial shear strength tests. Results demonstrate highly effective material segregation; the underflow was classified as Silty Sand (SM) with a significantly higher specific gravity (Avg. 3.26) compared to the finer, flaky particles in the overflow (Avg. 2.97). All samples were determined to be non-plastic. Mechanical testing indicated that the underflow achieved a superior maximum dry density (1990 kg/m³) and an enhanced effective angle of internal friction (ϴ’) of 38°, suggesting significantly higher shear strength for embankment construction. X-ray Fluorescence (XRF) analysis confirmed that iron (Fe) concentration was highest in the underflow (38.711%), while silicon dioxide (SiOsub2/sub) dominated the overflow (50.047%), correlating mineral density with geotechnical performance. While stable under compacted conditions, the non-plastic nature of these materials necessitates strict drainage management to mitigate potential stability loss upon saturation. These findings provide critical baseline parameters for the design and safety assessment of modern IOT storage facilities.