Estudi de la dinàmica del transport de dilucions salines d'alta concentració en canonades a pressió

Resumen

The mining area in the Bages district, in Catalonia (Spain), is located between the villages of Cardona, Súria, Sallent and Balsareny. It contains the most important salt deposit in Europe, which has been exploited since 1923 in order to extract potash, an essential agricultural fertilizer and a key element in the chemical industry. The exploitation of these potash mines quickly produced a salinization problem in the waters of Llobregat river, which already were the drinking water source for the city of Barcelona, so during the 1930s people started claiming for the construction of a pipe in order to canal the waste generated in the mines (sodium chloride in particular) to the sea, to avoid its runoff to the river. Nevertheless, this pipe (named Col·lector de salmorres) didn't become a reality since 1983. The total length of the facility far exceeds 100 km, it's a gravity-fed system and its flow is pressurized. The fact of transporting mining waste through a pipe of such high length increases the difficulty in the management of the infrastructure. Problems related with leakages or evacuation capacity losses are common, either because of seal oxidation, salt precipitation, solid particles sedimentation or any other possible cause. The objective of this work is to study the hydraulic behavior inside a pressure pipe of the residual brines generated in the Bages salt mines, by gathering flow rate, pressure and temperature data of a brine flow in a controlled environment (laboratory) and in the Col·lector de salmorres. First of all, a series of tests have been carried out with brines produced with water and salt extracted from the mines of Súria, at different concentrations. These tests have been performed in two different experimental loops constructed in the Fluid Mechanics Laboratory at the Civil Engineering School of Barcelona. The tests have enabled the determination of the viscosity of the generated brines. Secondly, the behavior of some brines with a constant salt concentration and different concentrations of insoluble particles has been analyzed, by performing a series of tests in an experimental loop located at the laboratory of the company Paterson & Cooke, in its headquarters in Cape Town (South Africa). These tests have enabled the determination of the limit deposition velocity of the solid particles in suspension of the generated brines. Finally, a field measurement campaign has been performed to monitor a segment of the Col·lector de salmorres. From the flow rate, pressure and temperature data, the behavior of this facility is discussed, considering the results obtained in the laboratory tests.