Correction to: Projection of Iron Ore Production

Natural Resources Research - The original version of this article unfortunately contained an error in Equation 3.     

Effects of monsoonal rainfall on waste dump stability and respective geo-environmental issues: a case study

The stability of mine waste dumps is of critical importance and an issue, the mining industry of Goa, India is continually facing. The State of Goa receives high rainfall of around 3,000 mm annually. This heavy monsoonal rainfall is often believed to be the cause of dump slope instability. In light of several dump collapses encountered in the State and their damaging effects on both mine operations and local geo-environmental conditions, this paper examines their stability considering various geotechnical factors and the downstream environmental effects of a slope failure. The mechanical properties of dump waste material are reported at different compaction levels. The effect of these properties and changes in pore-water pressure are specifically examined using limit equilibrium analysis. An empirical formula is developed relating dump height, material mechanical parameters and pore-water pressure to the factor of safety of the slope. It was found that the level of compaction experienced by the material had a significant effect on the factor of safety.     

Mechanical Behaviour of Reservoir Rock Under Brine Saturation

Acoustic emissions (AE) and stress–strain curve analysis are well accepted ways of analysing crack propagation and monitoring the various failure stages (such as crack closure, crack initiation level during rock failure under compression) of rocks and rock-like materials. This paper presents details and results of experimental investigations conducted for characterizing the brittle failure processes induced in a rock due to monocyclic uniaxial compression on loading of two types of sandstone core samples saturated in NaCl brines of varying concentration (0, 2, 5, 10 and 15 % NaCl by weight). The two types of sandstone samples were saturated under vacuum for more than 45 days with the respective pore fluid to allow them to interact with the rocks. It was observed that the uniaxial compressive strength and stress–strain behaviour of the rock specimens changed with increasing NaCl concentration in the saturating fluid. The acoustic emission patterns also varied considerably for increasing ionic strength of the saturating brines. These observations can be attributed to the deposition of NaCl crystals in the rock’s pore spaces as well some minor geo-chemical interactions between the rock minerals and the brine. The AE pattern variations could also be partly related to the higher conductivity of the ionic strength of the high-NaCl concentration brine as it is able to transfer more acoustic energy from the cracks to the AE sensors.