Reología de los Residuos Post-Flotación de Pb-Zn en la Sierra de Cartagena: La Unión (SE España)

Abstract

Los fenómenos de campo, como las licuefacciones estática y dinámica, se pueden acometer mediante ensayos de flujo y dinámicos, respectivamente. De hecho, un modelo de deslizamiento que utilizaba resultados reológicos como entrada, predijo valores coherentes de máxima velocidad y distancia recorrida para la falla de flujo de El Descargador. Finalmente, la tensión crítica de cedencia del lodo se puede asimilar al concepto de tensión de cizalla residual en mecánica de suelos, lo que abre una puerta para usar estos estudios como complemento a los ensayos triaxiales en la resolución de problemas de estabilidad. FUNDAMENTAL CONCEPTS OF CONTINUUM MECHANICSContinuum mechanics deals with the analysis of the kinematics and the mechanical response of materials, modeled as a continuous mass rather than as discrete particles. The following is a definition of the main variables involved with flow and deformation of materials.In a Newtonian liquid σ = η , where the strain rate is proportional to the applied stress σ and viscosity η is the constant of proportionality.During rainfall, additional amounts of water enter the deposit. Part of it infiltrates and the rest will flow as surface runoff, finally reaching the decant pond. Evaporation also occurs on the tailings surface. Usually, the position of discharge points is regularly changed, so as to manage the levels of the tailings within the deposit and to control the position of the decant pond. Evaporation rate induces an ascending flow by capillary rise, fed from the phreatic surface. Drying rate of a porous material is a complex phenomenon, During consolidation, water expelled from the material voids joins the infiltrated water, increasing the amount of water to be drained from the deposit. The reduction of porosity due to consolidation, changes the hydraulic properties of tailings, lowering the conductivity and increasing capillary rise. On the other hand, tailings above the phreatic surface remain in unsaturated condition. The resulting matric suction leads to the capillary  Reclaim water  Reclaim process reagents  Reclaim energy  Maximize density of tailings  Minimize ecological footprint  Render waste suitable for mine backfill  Reduce acid drainage  Reduce risk of dam failure Figure 1.5. (a) Types of mine tailings according to its solid/liquid ratio, including profiles for gravimetric water content, saturation degree, and water volume fraction. (b) Comparison between w/w and v/v ratios for a particle density of 3 g/cm 3 . low for sand-and silt-size tailings.According to expression 1.2, when the pore water pressure increases, the shear stress resistance of the material decreases and at some point the geotechnical stability of the dam is lost. The pore pressure rises because of excessive dam rising rate, transit of machinery, blasting, seismic events, injection of water due to failure of the drainage system… A contractive material under a cyclic shear test-which causes an increasing shear strain (Figure 1.7b)-will rise its water pore pressure gradually, originating...

Static Liquefaction Causes the Flow Failure of a Tailings Dam: A Case Study of El Descargador, Cartagena–La Unión Mining Region, SE Spain (October 1963)

“…4 km 2 in the periurban area of La Unión town, affecting different infrastructures such as the Cartagena-Cabo de Palos highway and the Cartagena-Los Blancos railroad), and the Beal wadis stream. A large amount of released acidic waters polluted the El Mar Menor coastal lagoon, which currently shows concentrations of metals and other mining pollutants well above the quality standards [63,69,70]. The impacts of the dam flow failure could have been of greater magnitude if LL3 had not dammed the stream flow in the early stages of the tailing slurries releasing.…”