Pneumatic conveying of ice particles through mine-shaft pipelines

A pilot-plant experimental investigation is described into the pneumatic conveying of large ice particles through long pipelines extending down deep mine shafts. Using low-pressure plastic piping with an inner diameter of 136 mm and cylindrical ice particles with initial dimensions of up to 34 mm, the main testing programme encompassed ice flow rates of up to 7.4 kg/s through a pipeline 2968 m long and extending to a depth of 1770 m below the surface. Ice was also delivered to a depth of 2407 m below the surface through a pipeline 3905 m long. Various regimes of two-phase flow were observed in the various vertical and horizontal sections of the pipeline, including dilute-phase flow and cohesive plug flow. Equations are presented for the prediction of pressure gradients along the respective sections, with empirical correlations for solids friction factors. The investigation proved the feasibility of conveying ice underground for mine-cooling purposes.

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