Development of granular materials for fluidized bed process: measuring attrition resistance with a horizontal ball milling device and its mathematical description

• A setup is presented, easy to operate & eligible for small amount of material test.
• Wide range of granulates attrition modes can be tracked by the developed method.
• Modes of abrasion and fragmentation in the same attrition test can be distinguished.

Attrition caused granulates degradation (abrasion or fragmentation) is often encountered in fluidized bed processes. Efforts to investigate attrition induced bed materials mass loss or size change require suitable test methods to track the occurrence of respective attrition modes (abrasion, fragmentation, or both) and clarify their individual influences. In this work, an easy operated horizontal ball milling test method, eligible for small amount test material and thorough collection of attrition generated fines, was developed. With this test setup, a wide range of attrition modes can be ‘created’, simply by changing the geometrical size of the ball milling media or the weight ratio between ball milling media and tested sample. Thanks to the knowledge of Epstein's particle rate-breakage theory and Austin equation, a two-parameter mathematical descriptive equation y = AXb1eb2(X − 1), including both abrasion term and fragmentation term, is developed. Solutions obtained from least square method, b1 and b2, enable us to distinguish the abrasion from fragmentation. This work provides an interesting characterization method to the understanding of granulates' attrition mechanism.

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