| Resumo : |
The present research couples the significantly large production of rock-crushing fines worldwide and the continued necessity of implementing a safe and efficient disposal strategy with the ideal medium provided by geotextile-assisted containers for dewatering high water content sediments, bringing in contributions to two meaningful aspects of the problem: the necessity of reliable tools for evaluating the retention capacity of geotextile filters and the comprehension of dewatering behavior when non-unidirectional flow is considered, condition inherently involved with most of field dewatering applications within waste containment. In this context, two main research lines have been established: the first comprising a new image-analysis technique towards nonwoven geotextiles, aimed at enhancing the determination of parameters that allow the assessment of the filter retention capacity with the use of a rational approach, specifically, the geotextile pore size distribution curve, a crucial element for accurately employing that method; and the second consisting of dewatering tests in a laboratory-scale box-type container, in the direction of investigating the filtration behavior of geotextiles dewatering rock-crushing fines and of fostering a better understanding as to the mechanisms involved. Three types of experimental analysis were performed: allowing flow of liquid in both vertical and horizontal directions, considering only vertical flow and considering only horizontal flow. The majority of tests presented high filtration efficiencies, and the compatibility between the characteristic opening size of geotextiles and the granulometry of rock-crushing fines is believed to be the governing aspect of dewatering. Finally, this work also validates the applicability of aforesaid rational approach to the prediction of retention capacity of geotextile filters employed in dewatering systems similar to that in study. The pore size distribution curve of the nonwoven geotextile investigated through the rational method takes into account manufacturing aspects with great mathematical accuracy, and leads to an excellent approximation of the filter retention capacity within the dewatering tests performed. |