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The morphological, flow and failure characteristics of fractionated natural bulk material. Evaluation of flowability of fractionated powdered liquorice using a specially designed flowmeter. The particle morphology was assessed by computer image analysis and the failure properties by shear cell testing.
Zolfaghari, Mohammad Esmail
Zolfaghari, Mohammad Esmail
Publication Date
2010-06-30T09:05:17Z
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The University of Bradford theses are licenced under a Creative Commons Licence.
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Accepted for publication
Institution
University of Bradford
Department
Postgraduate School of Studies in Powder Technology
Awarded
1986
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Abstract
With the technological development in biologically orientated
industries more and more natural products in powdered form are being
handled and processed.
Three differently comminuted liquorice rhizome products were
classified into 23 narrow size fractions to investigate the particle
and bulk characteristics of the material, and to study the influence
of particle shape on powder flowability.
The morphology of the fibrous particulate was investigated by
using a Quantimet 720 Image Analyser. The perimeter (P), projected
area (A), breadth (B), length (L), horizontal and vertical projected
lengths (P
V
and Pi) and the horizontal and vertical Feret diameters
(FV FH) were measured from which four dimensionless shape factors
were evaluated, [P2/47rA, PHxPV/A, L/B, FV/FH]. The surface texture of
the particles was measured by fractal analysis.
The influence of particle shape and size on the mean flow rate,
coefficient of flow variation and flow uniformity were measured using
a specially designed inclined tube flowmeter.
The failure properties of powdered liquorice when sheared under
known normal compressive stresses were measured and from a series of
yield loci the unconfined yield strength, major consolidation stress
and effective angle of internal friction were obtained. The effects
of particle shape and size on the angle of internal friction, wall
friction, bulk and packed densities were. investigated and the
experimental correlations expressed in terms of mathematical
equations. These relationships, together with the failure function
plots, indicate that comminuted liquorice powder behaves as a "simple"
powder.
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Type
Thesis
Qualification name
PhD