TitleNumerical and experimental analysis of breakage in a mill using the attainable region approach
NameMetzger, Matthew Joseph (author), Glasser, Benjamin J (chair), Pedersen, Henrik (internal member), Shapley, Nina (internal member), Hildebrandt, Diane (outside member), Rutgers University, Graduate School - New Brunswick,
SubjectChemical and Biochemical Engineering,
DescriptionBreakage of particulate materials is an essential process in many industries. Despite its prevalence, size reduction is one of the most inefficient unit operations in the collection of particulate processing operations. In this work, the breakage of granular materials in a batch ball mill, a commonly encountered industrial system, was investigated using computational and experimental techniques. Experimental analysis was performed in a bench-top mill with size analysis through standard sieve screening. Discrete element simulations (DEM) were carried out to examine the effect of a wide range of particle and operational parameters. Both experimental and computational results were analyzed using the Attainable Region (AR) approach. Breakage was found to be dependent on grinding media fill level, mill rotation rate, grinding media size and grinding time. At high energy inputs (large grinding media fill levels and high mill rotation rates) breakage varied little. For lower values of these parameters, breakage began to vary noticeably. The slowest mill rotation rate with the largest grinding media size was optimal (in terms of both time and energy usage) to produce the largest amount of a product of an intermediate size. It was also shown that variation of mill rotation rate could reduce the operating time of the mill by over 50% with minimal sacrifice of desired product, and that the inclusion of a feed bypass in the milling operation allows one to achieve product size distributions un-obtainable through milling alone. Computationally, single particle breakage simulations demonstrated agglomerate breakage was not always directly proportional to impact velocity, and thus breakage was a complex function of energy input. Good agreement between experimental and computational trends in a batch ball mill was found and the majority of breakage in a ball mill occurs near the mill shell, not at the surface where the grinding media and particles make contact. These findings contribute to the understanding of granular behavior in size reduction environments. Improved understanding of the particle breakage phenomenon will contribute to the development of more robust models and lead to improved energy efficiency and reduced operational costs in the industrial processing of granular materials.
NoteIncludes bibliographical references
Noteby Matthew Joseph Metzger
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.