Impact of the Fine Minerals Particles on Pentlandite Flotation by Andreas Mako Kusuma A thesis ...

128 Pages·2014·4.96 MB·English

Impact of the Fine Minerals Particles on Pentlandite Flotation

by

Andreas Mako Kusuma

A thesis submitted in partial fulfillment of the requirements for the degree of

Master of Science

in
Materials Engineering

Department of Chemical and Materials Engineering
University of Alberta

© Andreas Mako Kusuma, 2014
Abstract
In this study, the interactions between pentlandite and gangue minerals (i.e.
serpentine, olivine, magnesite) were investigated by directly measuring the zeta
potential distributions. In addition, an atomic force microscope (AFM) was used
to measure the interaction forces between a silicon nitride tip and gangue mineral
surfaces. Flotation tests were performed to understand the impact of the fine
gangue minerals on pentlandite recovery. The zeta potential distribution
measurements indicated an attractive interaction between pentlandite and
serpentine, and a repulsive interaction between pentlandite with both olivine and
magnesite at about pH 10 in 10 mM KCl solution. AFM force measurements
showed a repulsive interaction between an AFM tip with both serpentine and
olivine surface, and a slight attraction between an AFM tip and a magnesite
surface at pH 10 in 1 mM KCl solution. The repulsion between the tip and the
serpentine surface is possibly due to the measurement being performed on the
silica face of serpentine. The presence of olivine and magnesite did not show
detrimental effect on pentlandite recovery, as opposed to the pentlandite
depression observed in the presence of serpentine during the flotation at pH 10 in
5 x 10-4 M PAX solution. Similarly, the presence of serpentine also depresses
pentlandite recovery at pH 2.5 in 5 x 10-4 M solution.

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Preface
Chapter 3 of this thesis was submitted for publication to the Minerals Engineering
journal as Kusuma, A.M., Zeng, H., and Liu, Q., “Understanding interaction
mechanisms between pentlandite and gangue minerals by zeta potential and
surface force measurements”. I was responsible for the data collection and
analysis as well as the manuscript composition. Zeng, H. contributed to
manuscript edits. Liu, Q. was the supervisory author and was involved with
concept formation.
Chapter 4 of this thesis will be sent for publication to the Minerals Engineering
journal as Kusuma, A.M., Zeng, H., and Liu, Q., “Effect of the presence of fine
minerals towards pentlandite flotation”. I was responsible for the data collection
and analysis as well as the manuscript composition. Zeng, H. contributed to
manuscript edits. Liu, Q. was the supervisory author and was involved with
concept formation.
Part of the Chapter 3 of this thesis was presented at the PROCEMIN 2013
International Mineral Processing Conference.

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Acknowledgement
I would like to express my sincere gratitude and appreciation to my supervisors,
Dr. Qingxia (Chad) Liu and Dr. Hongbo Zeng for their support and guidance
throughout my MSc study. Moreover, Dr. Liu and Dr. Zeng have taught me many
valuable lessons which will be essential in my future career. From them, I also
learned about professionalism, safety at workplace, and more importantly, the
passion to a profession.
I would like to thank Ms. Erin Bobicki, Dr. Meijiao Deng, and Dr. Jingyi Wang,
from whom I had many fruitful discussions, and many have resulted in great
research ideas. Their expertise and knowledge had a very positive impact in this
study.
I would like to express my appreciation to Mr. James Skwarok, Mr. Shiraz
Merali, Ms. Meghan Curran, Ms. Zhaohui Qiu, Ms. Ling Zhang, Mr. Josh
Neumann, and Ms. Erin Furnell for their assistance in using equipment and
instruments. I would like to thank Dr. Shihong Xu and Gayle Hatchard for their
assistance in SEM instrument.
I would also like to thank Dr. Qingye Lu, who has helped me in proofreading
manuscripts and to whom I had many valuable discussions. I would like to thank
our research group’s administrative assistant Ms. Patricia Siferd and Mr. Carl
Corbett, for always being accommodating, resourceful, and supportive. Also
thanks to the past and present group members who have been great colleagues and
friends throughout my study.
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The financial support from Vale Ltd. and a Collaborative Research and
Development Grant from Natural Sciences and Engineering Research Council of
Canada (NSERC) are acknowledged. An award achieved by Dr. Hongbo Zeng
from the Canada Foundation for Innovation (CFI) for an AFM is also
acknowledged.
Finally, I dedicate this work to God, my father, my mother, my sister, my other
family members, and to all of my friends. Without their support, I wouldn’t have
reached this far.

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Table of Content
Chapter 1 Introduction ............................................................................................ 1
1.1 Uses and occurrence of nickel .................................................................... 1
1.2 Challenges in the flotation of low-grade ultramafic nickel ore .................. 2
1.3 Intermolecular and surface forces ............................................................... 6
1.3.1 Van der Waals forces ....................................................................... 6
1.3.2 Electrostatic double layer force ........................................................ 7
1.4 Objectives ................................................................................................... 9
1.5 References ................................................................................................. 10
Chapter 2 Experimental Techniques ..................................................................... 16
2.1 Zetaphoremeter ......................................................................................... 16
2.2 Atomic force microscope (AFM).............................................................. 19
2.3 Contact angle ............................................................................................ 21
2.4 Induction time apparatus ........................................................................... 22
2.5 Modified Hallimond tube .......................................................................... 23
2.6 Scanning electron microscope .................................................................. 24
2.7 References ................................................................................................. 25
Chapter 3 Understanding Interaction Mechanisms between Pentlandite and
Gangue Minerals by Zeta Potential and Surface Force Measurements ................ 28
3.1 Introduction ............................................................................................... 28
3.2 Experimental ............................................................................................. 31
3.2.1 Materials and reagents .................................................................... 31
3.2.2 Thermogravimetry analysis ............................................................ 32
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3.2.3 Zeta potential distribution measurements ....................................... 32
3.2.4 AFM force measurements .............................................................. 33
3.3 Results and discussion .............................................................................. 38
3.3.1 Thermal characteristic of serpentine .............................................. 38
3.3.2 Zeta potential distribution measurements of single mineral and
binary mineral mixture ............................................................................ 39
3.3.3 AFM force measurements .............................................................. 45
3.3.4 Interaction mechanisms of different minerals ................................ 52
3.4 Conclusions ............................................................................................... 54
3.5 References ................................................................................................. 55
Chapter 4 Effect of the Presence of Fine Minerals Particles towards Pentlandite
Flotation ................................................................................................................ 63
4.1 Introduction ............................................................................................... 63
4.2 Experimental ............................................................................................. 65
4.2.1 Materials and reagents .................................................................... 65
4.2.2 Contact angle measurements .......................................................... 66
4.2.3 Induction time measurements ......................................................... 67
4.2.4 Small scale flotation tests ............................................................... 68
4.3 Results and discussion .............................................................................. 69
4.3.1 Contact angle measurements on different minerals ....................... 69
4.3.2 Induction time measurements on different minerals ...................... 71
4.3.3 Flotation tests using a modified Hallimond tube ............................ 73
4.4 Conclusions ............................................................................................... 87
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4.5 References ................................................................................................. 88
Chapter 5 Conclusions and Contributions ............................................................ 94
5.1 Major conclusions ..................................................................................... 94
5.2 Contributions to the original knowledge................................................... 95
Chapter 6 Future Work ......................................................................................... 97
6.1 Future work ............................................................................................... 97
Bibliography ......................................................................................................... 99

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List of Tables
Table 3-1 The values used in the calculation of Hamaker constant A taken from
literature. ............................................................................................................... 37
Table 4-1 The contact angle values of different minerals..................................... 70
Table 4-2 The air bubble induction time on different mineral surfaces. .............. 73
Table 4-3 Pentlandite recovery in the presence of different gangue minerals and at
different pH. .......................................................................................................... 87

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List of Figures
Figure 2-1 Schematics of zeta potential distributions, illustrating: (a) the
individual zeta potential distributions of valuable and gangue minerals,
(b) the binary mixture with no attraction, (c) strong attraction in the
binary mixture (valuable mineral is fully coated with gangue mineral),
(d) strong attraction in the binary mixture (valuable mineral is partially
coated with insufficient amount of gangue mineral), and (e) weak
attraction in the binary mixture (valuable mineral is partially coated
with some amount of gangue mineral unattached). The figures are
adapted from Liu et al. (2002). ........................................................... 18
Figure 2-2 Schematic of working principle of an AFM. ...................................... 21
Figure 2-3 Schematic of contact angle formed by liquid droplets on a substrate. 22
Figure 2-4 Schematic of the induction time apparatus. ........................................ 23
Figure 2-5 Schematic of a modified Hallimond tube: (a) top and (b) bottom parts.
............................................................................................................. 24
Figure 3-1 Geometrical illustration of the conical AFM tip with spherical apex
interacting with a flat substrate. .......................................................... 36
Figure 3-2 TG analysis of serpentine heated under nitrogen atmosphere. ........... 39
Figure 3-3 The zeta potential of different mineral suspensions as a function of pH
in 10 mM KCl solution (∎ – serpentine, s – magnesite, H –
pentlandite, ● – olivine). ..................................................................... 41
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