Download understanding single particle breakage event to evaluate the effect

UNDERSTANDING SINGLE PARTICLE BREAKAGE EVENT TO EVALUATE THE EFFECT
OF APPLIED STRAIN RATE
Fatemeh Saeidi *, Mohsen Yahyaei, Malcolm Powell, Luis Marcelo Tavares
Julius Kruttschnitt Mineral Research Centre/ The University of Queensland, Brisbane, Australia, PhD
Candidate, +61 7 3365 5866, [email protected]
Julius Kruttschnitt Mineral Research Centre/The University of Queensland, Brisbane, Australia/Research
Fellow, +61 7 3365 5825, [email protected]
Julius Kruttschnitt Mineral Research Centre/The University of Queensland, Brisbane, Australia, Chair in
Comminution, +61 7 33655893, [email protected]
Department of Metallurgical and Materials Engineering (COPPE), Universidade Federal do Rio de
Janeiro/Head of Laboratory of Technology, +55 21 2290-1544, [email protected]
ABSTRACT
Understanding a single breakage mechanism is fundamental to development of breakage testing techniques
appropriate for mechanistic modelling of any breakage equipment. In the light of this insight, it is also
possible to compare any two breakage events in a mechanistic manner. This paper presents a new method
to compare breakage mechanisms of two-point impact with compression, different in their applied strain
rates. This approach regards a single breakage event as a process affected by three sub-processes; first
fracture, capture and spatial distribution of fragments. Spatial distribution is influenced by kinetic energy
of fragments and their brittleness. Using this methodology allows us to examine how each sub-process is
influenced by applied strain rate and its impacts on progeny size distribution. For this purpose, two rock
types of widely different strength, magnetite and silicate, were tested at various energy levels using the
short impact load cell (SILC) and Instron compression device. To isolate the effect of spatial distribution of
fragments, particles were forced to remain in the breakage zone. In this condition, similar progenies were
generated from compression and impact mechanisms at similar energy levels. However, allowing natural
distribution of fragments, coarser progeny was produced from compression for both rock types.
Additionally, using this approach provides a physical meaning and explanation for rock strength
parameters such as A×b in the t10-Ecs relationship.
KEYWORDS
Breakage, Spatial distribution, Fragments, Compression, Impact