|
|
Acknowledgements
|
3
|
|
|
Contents
|
9
|
|
|
List of Figures
|
13
|
|
|
Abbreviations and Notations
|
19
|
|
|
Introduction
|
21
|
|
1
|
Electrostatic Separation Processes: Control Variables and Measurement Techniques
|
25
|
|
1.1
|
Electrostatic separation: a multifactor process
|
26
|
|
1.1.1
|
Roll-type corona-electrostatic separation
|
26
|
|
1.1.2
|
Free fall tribo-electrostatic separation
|
28
|
|
1.2
|
Measurement techniques for electrostatic processes
|
32
|
|
1.2.1
|
Charge measurements
|
33
|
|
1.2.2
|
High voltage measurements
|
34
|
|
1.2.3
|
Surface potential measurement
|
35
|
|
1.3
|
Virtual instruments
|
38
|
|
1.3.1
|
Data acquisition techniques
|
39
|
|
1.3.2
|
Graphical programming
|
39
|
|
1.3.3
|
Developing virtual instruments in LabVIEW
|
40
|
|
2
|
Charge Measurements of Finely Divided Matter
|
43
|
|
2.1
|
Charge of insulating particles
|
43
|
|
2.1.1
|
Experimental set-up for measuring the charge of insulating particles in roll-type corona separators
|
46
|
|
2.1.2
|
Virtual instrument for single particle charge measurement
|
47
|
|
2.1.3
|
Discharge of insulating particles on the surface of the grounded roll electrode of a corona separator
|
54
|
|
2.2
|
Charge of insulating powders
|
59
|
|
2.2.1
|
Experimental setup for measuring the tribocharge of insulating powder
|
59
|
|
2.2.2
|
Virtual instrument for powder charge measurements
|
62
|
|
2.2.3
|
Variables that express the charge of insulating powders
|
64
|
|
2.3
|
Statistical control of tribocharging processes
|
67
|
|
2.3.1
|
Capability of a tribocharging device
|
69
|
|
2.3.2
|
Charts for the statistical control of a tribocharging process
|
72
|
|
2.3.3
|
Monitoring tribocharging processes - perspectives
|
76
|
|
|
Conclusions to Chapter 2
|
77
|
|
3
|
Surface Potential Measurement of Insulating Granular Layers
|
79
|
|
3.1
|
Surface potential of insulating granular layers
|
80
|
|
3.1.1
|
Experimental set-up for surface potential measurements of charged insulating granular layers
|
80
|
|
3.1.2
|
Virtual instrument for surface potential decay measurement
|
83
|
|
3.1.3
|
Surface potential decay of charged insulating granular layers
|
84
|
|
3.2
|
Charge decay characteristics of insulating granular layers at the surface of grounded electrodes
|
86
|
|
3.2.1
|
Discharge of insulating particles in contact with a grounded electrode
|
86
|
|
3.2.2
|
Charge decay as function of the nature of the granular material
|
89
|
|
3.2.3
|
Charge decay as function of ambient conditions
|
92
|
|
3.3
|
Method for evaluating the feasibility of corona-electrostatic separation of granular insulators
|
94
|
|
3.3.1
|
Experimental procedure
|
95
|
|
3.3.2
|
Surface potential decay of HDPE and PVC granular layers
|
96
|
|
3.3.3
|
Corona-electrostatic separation of PE and rubber
|
101
|
|
|
Conclusions to Chapter 3
|
103
|
|
4
|
High Voltage Measurement in Corona Electrostatic Separators
|
105
|
|
4.1
|
High-voltage energizing of corona electrodes
|
106
|
|
4.1.1
|
Experimental set-up for measuring the high voltage in corona separators
|
107
|
|
4.1.2
|
Spark discharge monitoring
|
108
|
|
4.1.3
|
High-voltage supply response to spark discharges
|
109
|
|
4.2
|
High-voltage sensing of the metal content in granular mixtures
|
112
|
|
4.2.1
|
Virtual instrument for high voltage measurements
|
114
|
|
4.2.2
|
Statistical analysis of high-voltage measurement data
|
115
|
|
4.3
|
Measurement of low metal contents in granular mixtures using a high-voltage sensor
|
123
|
|
4.3.1
|
High-voltage signal processing
|
124
|
|
4.3.2
|
Monitoring metal content in granular mixtures processed by electrostatic separation
|
127
|
|
|
Conclusions to Chapter 4
|
133
|
|
5
|
Modelling Metal / Insulator Separation Process
|
135
|
|
5.1
|
A linear-interaction model for electrostatic separation processes
|
136
|
|
5.1.1
|
Problem formulation using Taguchi methodology
|
137
|
|
5.1.2
|
Experimental implementation of Taguchi methodology
|
144
|
|
5.1.3
|
Interpreting the linear-interaction model
|
147
|
|
5.2
|
Robust control of electrostatic separation processes
|
150
|
|
5.2.1
|
Taguchi's approach to robust design
|
151
|
|
5.2.2
|
Experimental setup and results
|
154
|
|
5.2.3
|
Model for a robust electrostatic separation process
|
157
|
|
5.3
|
Effect of ambient humidity on the outcome of electrostatic separation processes
|
161
|
|
5.3.1
|
Formulation of the robust design problem
|
162
|
|
5.3.2
|
The classic analysis approach
|
166
|
|
5.3.3
|
The interaction analysis approach
|
168
|
|
|
Conclusions to Chapter 5
|
175
|
|
|
Conclusion and Contributions
|
177
|
|
|
References
|
181
|
|
|
Appendix A: Charge measurements: LabVIEW instrument implementation
|
197
|
|
|
Appendix B: Discharge graph identification: results for insulating particles on a grounded plate
|
203
|
