Microstructural properties and grinding of γ-Al2O3 and coal for environmental applications

Cheng Cheng, Stephen Adegbite, Jumoke Oladejo

Research output: Journal PublicationArticlepeer-review


The amphoteric characteristics of some metal oxides complemented by their chemical microstructures form the basis for their use for environmental engineering applications, e.g., alumina as catalyst and abrasive agents. This paper describes the microstructural properties and grinding behavior of γ-Al2O3 and coal particles in a batch impact mill. By grinding γ-Al2O3 and Hunan coal separately in an impact mill, a grinding process model of two dimensionless groups Π1* and Π2 is developed using Buckingham Pi theorem to obtain the desired particle morphologies. The properties established in this grinding model as key determinants of the grinding behavior are particle hardness, particle density and milling speed. The milling results confirm that γ-Al2O3 of the HBW 5/100 hardness 247 show higher resistance to grinding than coal of HBW hardness 28, because the final ground particle diameters d0.9 after 30 min milling were 136.6 and 33.4 µm for γ-Al2O3 and coal, respectively. This grinding model is pioneering as the particle hardness contained in the dimensionless group Π1* embodies an intrinsic material property which controls grinding and is confirmed to be in agreement with the fragmentation pattern.

Original languageEnglish
Pages (from-to)725-731
Number of pages7
JournalParticulate Science and Technology
Issue number6
Publication statusPublished - 18 Aug 2019


  • Alumina
  • coal
  • fragmentation
  • modeling
  • particle hardness
  • particle size distribution

ASJC Scopus subject areas

  • Chemical Engineering (all)


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