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Effects of loading mechanisms and texture on ore breakage – A multidimensional study
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.ORCID iD: 0000-0002-6284-5792
2020 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

 In comminution machines, the product properties (particle size distribution, mineral liberation characteristics) and process consumables (energy for size reduction, wear) are affected by various parameters. On the one hand, understanding and optimizing these parameters can provide an energy efficient process and a specified product. On the other hand, a fundamental understanding of the breakage process can even be used for designing new or improved comminution machines. In this thesis, breakage fundamentals are analyzed and set against the principles of various comminution machines. The study of the breakage fundamentals is crucial for a better understanding of the effect of different comminution environments on ore types and their textures in order to achieve a desired product size and liberation. This work defines three main areas of breakage processes with breakage fundamentals, namely “loading mechanism”, “breakage mechanism” and “breakage mode”. The “loading mechanism” is defined as the physical action that is applied to a particle or several particles in order to introduce mechanical stress. The resulting pattern of the particle failure is named “breakage mechanism”. Finally, the “breakage mode” defines the particle breakage in terms of being random or non‐random. Non‐random breakage depends on the ore texture, which can be categorized as preferential breakage and phase boundary breakage. Promoting the breakage mode to the phase boundary breakage could help to increase the liberation degree. Various studies have assessed the effect of ore texture and operational parameters on mineral liberation. While ore texture is related to the particle inherent characteristics, operational conditions such as loading mechanism are related to the comminution environment. In all these investigations, little attempt has been made to explore the combined effects of loading mechanism and quantitative ore texture features on breakage mode and mineral liberation. In addition, a lack of fundamental understanding of the breakage process and mineral liberation can be seen. Accordingly, a more fundamental study of the causes behind the effects of loading mechanism and texture is required in order to optimize the comminution process in terms of mineral liberation. The objective of this work is, therefore, to investigate the effects of different loading mechanisms on particle breakage and breakage mode. In order to achieve this goal, work has started with using two methods including three‐dimensional deformation and two‐dimensional crack quantification. The former method involved X‐ray computed micro‐tomography (XCT) imaging and Digital Volume Correlation (DVC) measurements which determiners the breakage mode in terms of being random or non-random. Whereas the latter was done using an image processing code in MATLAB to quantify cracks in terms of random and non-random breakage (preferential or phase boundary) from Scanning Electron Microscopy (SEM) images. In addition, XCT 3D imaging was used in order to track the propagated cracks in the third dimension. Moreover, phase boundary breakage in magnetite grains was studied qualitatively based on optical microscopy images in order to identify and characterize the propagated cracks.

Place, publisher, year, edition, pages
Luleå University of Technology, 2020.
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
Keywords [en]
Breakage mechanism, Loading mechanism, Ore texture, Liberation, Comminution
National Category
Geosciences, Multidisciplinary Metallurgy and Metallic Materials
Research subject
Mineral Processing
Identifiers
URN: urn:nbn:se:ltu:diva-78068ISBN: 978-91-7790-554-7 (print)ISBN: 978-91-7790-555-4 (electronic)OAI: oai:DiVA.org:ltu-78068DiVA, id: diva2:1414725
Presentation
2020-05-11, F1031, Luleå, 13:00 (English)
Opponent
Available from: 2020-03-16 Created: 2020-03-15 Last updated: 2023-09-05Bibliographically approved
List of papers
1. Breakage process of mineral processing comminution machines – An approach to liberation
Open this publication in new window or tab >>Breakage process of mineral processing comminution machines – An approach to liberation
2020 (English)In: Advanced Powder Technology, ISSN 0921-8831, E-ISSN 1568-5527, Vol. 31, no 9, p. 3669-3685Article in journal (Refereed) Published
Abstract [en]

Mineral liberation and size reduction are the most critical steps before mineral separation. Several investigations showed that mineral liberation degree could be affected by ore texture and/or loading mechanisms. However, varied definitions have been used for the breakage fundamentals as the leading cause of mineral liberation. This review identifies the breakage fundamentals and analyzes them in terms of process and ore breakage behavior. It is highlighted that the breakage fundamentals are essential for optimizing of comminution environments and designing the comminution machines. Three main areas of breakage processes in regard to fundamentals of breakage are classified and addressed as “Loading mechanism”, “Breakage mechanism”, and “Breakage mode”. Despite the fact that many advances have been made in the design of the comminution machines; still, the combined effect of breakage fundamentals and ore properties such as ore texture in a quantitative manner is not fully understood. In this regard, this study identifies and discusses the material and process factors influencing the breakage phenomenon. This potentially paves the way for improving the comminution environment concerning a particular ore type.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Breakage mechanism, Loading mechanism, Ore texture, Liberation, Breakage mode
National Category
Metallurgy and Metallic Materials
Research subject
Mineral Processing
Identifiers
urn:nbn:se:ltu:diva-78064 (URN)10.1016/j.apt.2020.08.005 (DOI)000579717400001 ()2-s2.0-85090481232 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-11-09 (johcin)

Available from: 2020-03-15 Created: 2020-03-15 Last updated: 2023-12-19Bibliographically approved
2. Characterization of ore texture crack formation and liberation by quantitative analyses of spatial deformation
Open this publication in new window or tab >>Characterization of ore texture crack formation and liberation by quantitative analyses of spatial deformation
2020 (English)In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 157, article id 106577Article in journal (Refereed) Published
Abstract [en]

In comminution, particle breakage starts with crack induction and propagation. The path of cracks defines the breakage mode, e.g. preferential in phase breakage or phase boundary breakage. For investigating crack formation behavior, the description by displacement fields can be applied. The displacement fields of the mineral phases can then be used to understand breakage mode and liberation. Ore texture and operational conditions such as loading mechanisms will affect the system. One of the ore texture aspects is the ore texture heterogeneity, which is a complex quantity comprising mineral heterogeneity, geometrical heterogeneity, weak grain boundaries, and micro-cracks. This study aims at investigating the effects of ore texture and loading displacement rate on minerals breakage mode. By knowing minerals breakage mode it is possible to identify the factors which affect minerals liberation and optimizing these factors in order to liberate minerals even in coarser size fractions. The approach is to describe the spatial displacement fields in different ore textures. In order to obtain these, in-situ compression loading tests with different displacement rates were conducted, followed by X-ray computed micro-tomography (XCT) and Digital Volume Correlation (DVC). In addition, the resulting cracks from ore breakage were analyzed and quantified in order to analyze the breakage mode. Moreover, XCT imaging was used for tracking the propagated cracks in the third dimension. For identifying mineral phases, automated scanning electron microscopy (SEM) complemented by energy dispersive spectroscopy was applied. The outcomes showed that both ore texture and loading mechanism should be considered for describing crack formation and consequently mineral liberation.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Crack quantification, Spatial deformation, X-ray computed micro-tomography, Ore texture, Breakage mode
National Category
Metallurgy and Metallic Materials Applied Mechanics
Research subject
Mineral Processing; Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-78065 (URN)10.1016/j.mineng.2020.106577 (DOI)000564536800008 ()2-s2.0-85088841372 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-08-20 (alebob)

Available from: 2020-03-15 Created: 2020-03-15 Last updated: 2023-12-19Bibliographically approved

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Semsari Parapari, Parisa

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