Insights into the mechanics of uncemented and lightly cemented compacted iron ore tailings under high confining pressures

Abstract

Grading changes due to particle breakage are crucial in geotechnical engineering problems involving high pressures, such as elevated-height dry stacking facilities for compacted filtered iron ore tailings disposal. However, understanding the iron ore tailings response at high stress is still in its early stages in the Brazilian context. It is now marked by the increasing need for alternatives to tailings allocation rather than the traditional slurry disposal in impoundments. The present research, which examines the mechanical response of iron ore tailings and lightly cemented iron ore tailings over confining pressures ranging from 1.2 to 120 MPa for dry stacking purposes, provides significant insights into this area. The study relied on triaxial tests conducted on a high-pressure apparatus that employed specimens compacted at three different compaction degrees. The cement addition incurred slight differences in isotropic compression, enlarging the range of achievable states. Still, the shearing response of both uncemented and lightly cemented tailings was very similar, particularly at higher stress levels, resulting in an equivalent critical state locus. In the v- ln ṕ plane, an S-shaped function described the critical state and delineated the regions where particle breakage becomes an important source of volumetric strain. In brief, this study provides novel insights into the behaviour of uncemented and lightly cemented iron ore tailings in the context of elevated-height dry stacking facilities.

Keywords

• Iron ore tailings
• Cement
• High-pressure triaxial testing
• Particle breakage
• Critical state