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Dewatering Process (dewatering + process)
Selected AbstractsThe possible hydrologic effects of the proposed lignite open-cast mining in Drama lignite field, GreeceHYDROLOGICAL PROCESSES, Issue 11 2008Sotiris Panilas Abstract The present study investigates the possible hydrologic effects of the proposed lignite open-cast mining in Drama lignite field (north Greece). Recent years have seen a rapid increase in surface mining. This activity has generated a growing concern for the potential environmental impacts associated with large scale surface mining. In order to achieve a safe mine operation and allow extraction of lignite to considerable depths, extensive dewatering by pumping will be necessary, while at the same time it is desirable to avoid presence of overpumping conditions in the broader area. Based on stratigrafic, hydrologic and hydrogeologic data, a three-dimensional finite difference model was developed in order to simulate the dewatering process of the western part of the lignite open-cast mine in Drama and to predict both spatially and temporally the decline of ground water level down to the lignite surface. The dewatering of the part of the aquifer which underlies the mine area will influence the hydrological conditions of the broader region. The most important anticipated effects will be the abandonment of shallow wells as well as the decrease of ground water pumping rates of deep wells. Aquifer discharge towards the ditches of the study area will cease and there will be an inversion of ground water flow from the ditches towards the underlying aquifer. Dewatering activities will probably result in minor subsidence of the nearby peat deposits of Drama Philippi marshes. Moreover, sand pumping as well as the presence of gasses is likely to cause local subsidence phenomena, mainly in the pit slopes. Copyright © 2007 John Wiley & Sons, Ltd. [source] One-dimensional model of vacuum filtration of compressible flocculated suspensionsAICHE JOURNAL, Issue 10 2010Anthony D. Stickland Abstract This work details the one-dimensional modeling of the different processes that may occur during the vacuum filtration of compressible flocculated suspensions. Depending on the operating conditions of the applied pressure and the initial solids concentration relative to the material properties of the compressive yield stress and the effective capillary pressure at the air,liquid interface, the dewatering process undergoes a combination of cake formation, consolidation, and/or desaturation. Mathematical models for these processes based on the compressional rheology approach are presented and appropriate solution methods outlined. Results using customary material properties are given for different operating conditions to illustrate the three dewatering processes. This approach lays the theoretical basis for further work understanding two- and three-dimensional effects during desaturation, such as cracking and wall detachment. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Fluid Dynamics and Thermal Aspects of the Dewatering of High-Alumina Refractory Castables: Removal of Physically Absorbed WaterJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2001Murilo D. M. Innocentini This article reports on an experimental investigation of the dewatering process of cement-free high-alumina refractory castables. Simultaneous fluid dynamic, thermal, and mass loss effects were investigated during the removal of physically absorbed water at temperatures of 25° to 700°C. The release of steam was decisively affected by the castable's permeability level and the heating rate applied. The analysis of fluid dynamics revealed that at 1°C/min, the main bulk of physical water was released as steam under saturated conditions at 100°C. However, at 5°C/min, steam was trapped within the pores, and water loss was chaotically released and shifted to higher temperatures. Thermal analysis showed that the endothermic boiling of water may result in a critical thermal shock in the castable's structure. Both steam entrapment and thermal shock were more severe with the reduction in the castable's permeability level. [source] Dimensionierung von Vakuumwasserhaltungen im tertiären FeinsandBAUTECHNIK, Issue 7 2004Peter-Michael Mayer Dr.-Ing. Der Entwurf umfangreicher Vakuumwasserhaltungen ist aufgrund fehlender allgemeingültiger analytischer Berechnungsverfahren bisher auf Abschätzungen und Erfahrungen angewiesen. Vorliegende Untersuchungen zeigen exemplarisch für eine 80 m lange und 37 m breite Spundwandbaugrube im tertiären Feinsand, wie mittels räumlicher Finite-Element-Modelle die erforderliche Anzahl und Tiefe von Vakuumtiefbrunnen zur Grundwasserabsenkung berechnet werden kann. Die Auswirkungen von Schichtanisotropien bzw. lokaler Bereiche mit hoher Durchlässigkeit auf das erreichte Absenkziel und die geförderten Pumpmengen werden aufgezeigt. Darüberhinaus wird auch der Wasserdruck auf die Spundwand analysiert. Die Bedeutung zeitabhängiger Strömungsberechnungen wird durch die Verbindung von Aushub und Wasserhaltung deutlich und kann durch instationäre Betrachtungen erfaßt werden. Der Vergleich von in-situ-Messungen und Berechnungsergebnissen zeigt die Leistungsfähigkeit, aber auch die Grenzen numerischer Strömungsmodelle bei der Abschätzung des Ausführungsrisikos und möglicher wirtschaftlicher Optimierungen. Dimensioning of vacuum dewaterings in tertiary fine sand. Because of outstanding valid analytical solutions, the study of extensive dewatering depends actually only on estimations and experiences. This paper show, for a 80 m long and 37 m large excavation in fine sand, how to calculate the requested number and depth of vacuum deep well for the lowering of the groundwater level by Finite-Element-Models. The effects of anisotropic layer and layer with local ranges with high porosity for the achieved lowering and pumping capacity have been showed. Additionally the water pressure on sheet pile wall was also analyzed. The significance of transient flow calculations becomes clearly by the connection of excavation and dewatering. The comparison of in-situ measurements and results of calculations shows the performance but also the limits of the numerical flow models on the estimation of the execution risks and possible improvement on dewatering process. [source] One-dimensional model of vacuum filtration of compressible flocculated suspensionsAICHE JOURNAL, Issue 10 2010Anthony D. Stickland Abstract This work details the one-dimensional modeling of the different processes that may occur during the vacuum filtration of compressible flocculated suspensions. Depending on the operating conditions of the applied pressure and the initial solids concentration relative to the material properties of the compressive yield stress and the effective capillary pressure at the air,liquid interface, the dewatering process undergoes a combination of cake formation, consolidation, and/or desaturation. Mathematical models for these processes based on the compressional rheology approach are presented and appropriate solution methods outlined. Results using customary material properties are given for different operating conditions to illustrate the three dewatering processes. This approach lays the theoretical basis for further work understanding two- and three-dimensional effects during desaturation, such as cracking and wall detachment. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] | ||||||||||