The influence of hematite particle shape on stratification in pipe flow

Abstract

This paper discusses the influence of hematite particle shape factor, through the sphericity function, on the concentration distributions of solids over the cross sectional area of the pipe for the hydraulic transportation of hematite industrial mineral concentrates. The results are depicted by figures of solids distribution along three sectors of the pipe cross sectional area of the pipe and the sphericity function of particles from each section were evaluated using the permeametry method. A recirculating pipeline testing loop with a transparent section and pipe diameter (D) of 50mm, with a special gutter device installed at the discharge of the test loop, was employed. The hematite mineral concentrate used is composed exclusively of coarse particles clustered in two particle size (d) ranges: 0.210mm<d<0.297mm and 0.105mm<d<0.149mm. The results of solids distribution profiles indicated that the coarser particle class yielded a more heterogeneous concentration profile over the cross sectional area flowing at the critical deposition velocity (VC). The slurry stratification inside the pipe was influenced by the particle shape factor evaluated by the sphericity function according to each pipe section. The higher the particle sphericity the more these particles were found at the bottom of the pipe. It was also observed that <6% of the bulk particles flowed in the top section of the pipe (0.8D from the bottom to the top) for any given condition.