Introduction
Smectite and Bentonite Terminology, Classification,
and Genesis .................................................... 15
H. Albert Gilg, Stephan Kaufhold & Kristian Ufer
1.1 Crystal structure systematics of the smectite group ....n... 15
1.2 Terminology and classification of smectites and bentonites . 18
1.3 Genesis of bentonite deposits .............................. 20
1.3.1 Primary bentonite deposits ............................... 22
1.3.1.1 In-situ alteration of volcanic and volcaniclastic rocks . 22
1.3.1.2 In-situ alteration of non-volcanic rocks ............... 29
1.3.1.3 Chemical precipitation of bentonites
in an aqueous environment ...................................... 31
1.3.2 Secondary bentonite deposits ............................. 31
The Samples Used in this Study ................................. 33
Stephan Kaufhold
2.1 Sample location and type ................................... 33
2.2 Sample preparation ......................................... 35
Sample Characterization ........................................ 39
Wen-an Chiou, Reiner Dohrmann, Stephan Kaufhold, Michael Plötze,
Joseph W. Stucki & Kristian Ufer
3.1 Drying ..................................................... 39
3.2 Grinding and disaggregation ................................ 42
3.3 Preparation of purified and homoionic materials ............ 46
3.4 Particle size fractionation ................................ 51
3.5 Submicron particle size analysis ........................... 53
3.6 Chemical composition of bentonite .......................... 62
3.7 Structural formula ......................................... 67
3.8 X-ray diffraction (XRD) .................................... 70
3.9 Characteristic intercalations for XRD analysis of smectites
................................................................ 74
3.10 Infrared spectroscopy (IR) ................................ 81
3.11 Thermal analysis .......................................... 84
3.12 pH of bentonites .......................................... 90
3.13 Permanent charge - layer charge density (LCD) ............. 93
3.14 Variable charge ........................................... 99
3.15 Tetrahedral and octahedral charge ........................ 104
3.16 Microstructure based on scanning electron microscopy
(SEM) ......................................................... 107
3.17 Smectite morphology ...................................... 110
3.18 External surface area .................................... 116
3.19 Internal and total surface area .......................... 119
3.20 Porosity of bentonites ................................... 124
3.21 Acidity of bentonites/smectites .......................... 127
3.22 Quantitative mineralogical composition ................... 130
3.23 Amorphous components ..................................... 134
3.24 Iron in smectites and bentonite admixtures ............... 139
Properties and Performance ..................................... 145
Reiner Dohrmann, Nils Rickertsen & Stephan Kaufhold
4.1 Cation-exchange capacity (CEC) ............................. 145
4.2 Rheological properties ..................................... 148
4.3 Critical coagulation concentration (CCC).................... 154
4.4 Water uptake ............................................... 159
4.5 Free swelling .............................................. 162
4.6 Swelling pressure .......................................... 166
4.7 Specific electrical resistivity............................. 171
Sources of Bentonite ........................................... 181
Michael Dörschug & Stephan Kaufhold
5.1 Exploration for new deposits .............................. 182
5.2 Mining .................................................... 185
5.3 Mining technology ......................................... 188
5.4 Quality management in the mine ............................ 190
5.5 Quality management in the laboratory ...................... 192
5.5.1 Bentonite composition ................................... 193
5.5.2 Water uptake and swelling ............................... 195
5.5.3 Rheological parameters .................................. 196
Processing .................................................... 199
Helmut Coutelle, Kisnaduth Kesore, Dietrich Koch, Stephan Kaufhold
& Nils Rickertsen
6.1 Historical development of bentonite processing ........... 199
6.2 Alkaline (soda ash) activation ............................ 200
6.2.1 Field activation ........................................ 201
6.2.2 Mechanical activation ................................... 202
6.2.3 Summary of alkaline activation of bentonites............. 204
6.3 Acid activation ........................................... 205
6.4 Organic activation ........................................ 209
6.5 Pillared clays............................................. 211
6.6 Industrial drying ......................................... 213
6.6.1 Natural (sun) drying .................................... 213
6.6.2 Technical drying ........................................ 214
6.7 Industrial grinding ....................................... 215
6.8 Purification .............................................. 217
6.9 Blending .................................................. 219
7 Applications ................................................ 221
Helmut Coutelle, Andreas Decher, Stephan Kaufhold,
Theodore Karidakis, Kisnaduth Kesore, Dietrich Koch,
Annette Krause, Nils Rickertsen & Albert Stützer
7.1 Dry form applications ..................................... 223
7.1.1 Adsorber ................................................ 223
7.1.2 Animal feed ............................................. 225
7.1.3 Landfill sealing ........................................ 227
7.1.4 Cat litter .............................................. 232
7.1.5 Foundry bentonites....................................... 234
7.1.6 Disposal of high-level radioactive waste (HLRW) ......... 238
7.1.7 Pelletizing ............................................. 245
7.1.8 Bentonites in ceramic bodies ............................ 248
7.2 Wet form applications ..................................... 250
7.2.1 Beverage treatment ...................................... 250
7.2.2 Civil engineering ....................................... 251
7.2.3 Drilling fluids ......................................... 259
7.2.4 Paper production ........................................ 262
7.2.5 Healing clay ............................................ 268
7.3 Use of special activated bentonites ....................... 269
7.3.1 Bleaching earths ........................................ 269
7.3.2 Catalysts ............................................... 270
7.3.3 Organoclays as rheological additives ..................... 271
7.3.4 Nanocomposites .......................................... 272
8 References .................................................. 275
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Acronyms and Abbreviations .................................. 305
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Appendix Procedure used for the production of Na-saturated
(purified) bentonites ......................................... 307
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About the Authors ........................................... 309
