Dense-phase pneumatic conveying of slush ice through plastic pipes

Ice is being used in certain deep mines to transport refrigeration to underground areas. Research has been carried out previously into the pipeline conveying characteristics of ice with air, but there remains a lack of knowledge about some aspects of this complex flow. Previous articles (Sheer, 1995; Sheer et al., 2001) have described experimental results on the pneumatic conveying of ice in particulate form ("hard" ice) through successive long horizontal and vertical sections of pipelines into mines. More recent research has been carried out to determine the conveying characteristics of "slush" ice that resembles wet snow, with an ice mass fraction range of 65-75%. Laboratory pneumatic conveying tests with slush ice were conducted through three horizontal plastic pipelines with inner diameters of 43, 54, and 69 mm, each pipeline being approximately 50m long and including various bends. The tests yielded numerical and photographic data that were used to investigate the conveying characteristics of slush ice (including flow regime transition to plug flow and pressure gradients) and to compare them with the previous results for particulate ice. It was found that the conveying characteristics of the slush depend strongly on the water content. Correlations are proposed for multiphase friction factors.