On the difficulties of sampling bulk powder blends in determining segregation propensity — A case study

• Industrial application blending two fine bulk powders
• Investigation of segregation propensity using sampling probes
• Calibration of samples via density comparisons
• Comparison of sample make-up compared with original test blend
• Importance of accuracy of sampling and of blend consistency

Whether a single product contains a wide particle size distribution or a combination of products is mixed to produce a blend, the handling of these materials often produces unwanted particle segregation. This paper reports on the findings of an industrial project to investigate the feasibility of blending pulverised coal and crushed nickel ore in a bulk material handling application, to produce nickel. These product blends require various different handling methods throughout the industrial process, making them susceptible to segregation. Representative samples of each bulk material and two pre-mixed blends were obtained and a range of tests were performed to quantify any segregation of the product blends after undergoing gravity discharge from a feed bin. The calibration process proved more difficult than similar segregation testing on granular materials. Initial test results showed a substantial variation to the original blend composition, however, further investigation found discrepancies with the initial material blends. Additionally testing was performed correcting for these differences, with the results showing better results.

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