Pyrite Oxidation and Its Control: Solution Chemistry, Surface Chemistry, Acid Mine Drainage

304 Pages·1995·16.55 MB·English

by  V.P. Evangelou

PYRITE
OXIDATIO
and
ITS CO ROL
Solution Chemistry, Surface Chemistry,
Acid Mine Drainage (AMD),
Molecular Oxidation Mechanisms, Microbial Role,
Kinetics, Control, Ameliorates and Limitations,
Mi croencapsulati on
Ve P .. (Bill) Evangelou, Ph.De
Professor of Soil/Water Physical Chemistry
University of Kentucky, Lexington
V~ CRC Press
Taylor & Francis Group
Boca Raton London New York
CRC Press is an imprint of the
Taylor & Francis Group, an informa business
Library of Congress Cataloging-in-Publication Data
Evangelou, V. P.
Pyrite oxidation and its control : solution chemistry, surface
chemistry, acid mine drainage (AMD), molecular oxidation mechanisms,
microbial role, kinetics, control, ameliorates and limitations,
microencapsulation I V.P. (Bill) Evangelou.
p. cm.
Includes bibliographical references and index.
ISBN 0-8493-4732-7 (permanent paper)
I. Acid mine drainage. 2. Pyrites--Oxidation.
3. Microencapsulation. I. Title.
TD899.M5E94 1995
622--dc20
DNLM/DLC
95-7044
This book contains information obtained from authentic and highly regarded sources. Re
printed material is quoted with permission, and sources are indicated. A wide variety of references
are listed. Reasonable efforts have been made to publish reliable data and information, but the
author and the publisher cannot assume responsibility for the validity of all materials or for the
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© 1995 by CRC Press
No claim to original U.S. Government works
International Standard Book Number 0-8493-4732-7
Library of Congress Card Number 95-7044
Printed in the United States of America 3 4 5 6 7 8 9 0
Printed on acid-free paper
PREFACE
After fourteen years of attendance and participation in numerous
conferences on acid mine drainage, two things have become apparent to the
author of this book. First, much of the basic knowledge on pyrite and its
oxidation mechanisms is not being used for the purpose of improving and/or
generating new knowledge on controlling pyrite oxidation, and second, not
much progress is being made in developing new technologies for controlling
pyrite oxidation. Thus, the need for a book on the basic knowledge of pyrite
and the use of this knowledge for generating new ideas, concepts and
technologies on oxidation and control became apparent.
The focus of this book is on pyrite oxidation theory, experimental
findings on oxidation mechanisms as well as application/limitations of
amelioration technologies. A discussion on the theory and potential
application of novel pyrite microencapsulation technologies for controlling
pyrite oxidation currently under investigation in the author's laboratory is also
included.
The book is designed to serve research faculty and graduate students
in mining/environmental engineering, geology, soil science and
environmental professionals dealing with amelioration of acid drainage
produced by pyritic waste. The book is not designed to be everything to
everybody. However, it is an attempt to gather the scientific knowledge on
pyrite and acid mine drainage, evaluate it and use it as a springboard to new
and improved control technologies.
I would like to thank all those who have contributed to my education
on pyrite and acid mine drainage. Special appreciation goes to Mr. R. W.
Hammack, and Dr. R. Kleinmann of the U.S. Department of the Interior,
Bureau of Mines Pittsburgh, PA, Ms. Patricia M. Erickson of the U.S. EPA,
Cincinnati, OH, and Dr. F. Caruccio of the University of South Carolina,
Columbia, SC, for the numerous enlightening discussions on pyrite oxidation
in the field.
Special thanks and appreciation go to Elisabeth Portig, laboratory
technician, Y. L. Zhang, Post-doctoral Fellow, Louis McDonald, Ph.D.
candidate, and Amy Bacon, undergraduate student, for their help in
completing this book.
THE AUTHOR
V. P. (Bill) EVANGELOU obtained his B.S. in 1972 and M.S. in 1974 in
Agriculture and Plant Science, respectively from California State
University, Chico. In 1980, he received his Ph.D in Soil Science
specializing in mineralogy and soil/water chemistry from the University
of California at Davis.
Dr. Evangelou is currently Professor of SoiJ/Water Physical
Chemistry at the University of Kentucky. He has served as Major
Professor to numerous graduate students and supervisor of a number of
Postdoctoral Fellows. He teaches courses in soil chemistry, soil physical
chemistry and chemistry of sulfate rich geologic environments.
Dr. Evangelou's research is focused on cation exchange
equilibria and kinetics of soils and day minerals, the surface chemistry of
soils, physical behavior of soil colloids, plant root cell wall-metal ion
interactions and acquisition by plants, kinetics of pyrite oxidation and
surface processes controlling rates of oxidation reactions, and recently,
organometallic complexes and herbicide colloid suspension interactions
and behavior. He has published more than 100 scientific papers on these
subjects and has conducted more than 30 short courses on the subject of
pyrite chemistry and acid mine drainage (AMD) for federal/state and
private industry professionals from the U.S.A., Canada, Europe and
South Africa. More than 2000 professionals have attended Dr.
Evangelou's short courses on pyrite oxidation and acid mine drainage.
He has been recognized for his scientific contributions by a number of
awards,
-Marion L. & Chrystie M. Jackson Soil Science Award, 1992, Soil Science
Society of America, outstanding contributions in the areas of soil
chemistry and mineralogy, and graduate student education.
-Fellow, American Society of Agronomy, 1993.
-Fellow, Soil Science Society of America, 1993.
-U.S. Patent (No. 5,286,522) on "Peroxide Induced Oxidation Proof
Phosphate Surface Coating on Iron Sulfides", 1994.
-Fulbright Scholar Award, 1994-1995.
-Thomas Poe Cooper Award, University of Kentucky, College of
Agriculture, 1994, distinguished achievement in research.
TABLE OF CONTENTS
IN1RODUCTION ..................................................................................... 1
PART I
REVIEW OF BASIC CONCEPTS OF SURFACE CHEMISTRY AND
CHEMISTRY AND CONTROL OF ACID DRAINAGE
CHAPTER 1
A REVIEW ON SOLUTION/MINERAL CHEMISTRY ........................ 7
1.1 Ion Activity versus Concentration .............................................. 7
1.1.1 Solution pH .................................................................. 8
1.1.2 Mineral solubility ......................................................... 9
1.1.3 Ion pairing .................................................................... 10
1.1.4 Ionic strength and ion pairing ...................................... 13
1.1.5 Specific conductance .................................................... 15
1.2 AcidityI Alkalinity ....................................................................... 20
1.2.1 Alkalinity speciation .................................................... 22
1.2.2 Neutralization potential ................................................ 24
1.2.3 Alkalinity contribution by CaC03 ............................... 25
1.3 Practical Implications ................................................................. 27
CHAPTER2
ELECTROCHEMICAL AND PHYSICAL PROPERTIES OF GEOLOGIC
MATERIAL .............................................................................................. 29
2.1 Introduction ................................................................................ 29
2.2 Aluminosilicate Minerals ........................................................... 29
2.3 Metal-Oxides .............................................................................. 30
2.4 Organic Matter ............................................................................ 31
2.4.1 Chemistry of humic substances .................................... 31
2.5 Clay Mineral Surface Charge ..................................................... 32
2.5 .1 Permanent structural charge ......................................... 33
2.5.2 Variable charge ............................................................ 36
2.6 Reaction Among Humic Substances, Clays, and Metals ........... .44
2.6.1 Mechanisms of complex formation ............................. .45
2.7 PZCpH and Potential Pyrite Oxidation Implications .................. 48
CHAPTER3
CHEMICAL AND PHYSICAL PROPERTIES OF MINE WASTE ....... 53
3.1 Mine Waste ................................................................................. 53
3.2 Chemical and Physical Properties .............................................. 59
3.2.1 Mine 'waste' surface chemistry .................................... 63
3.2.2 Technique comparisons ................................................ 65
3.2.3 Mine 'waste' solution chemistry ................................... 69
CHAPTER4
ACID DRAINAGE PRODUCTION CHEMIS1RY AND
PREDICTION ........................................................................................... 77
4.1 Pyrite Occurrence, Formation, Morphology and Chemistry ...... 77
4.2 Transitional Metal-Pyrite Oxidation ........................................... 82
4 .2.1 Effect of ferric hydroxide species on pyrite oxidation. 83
4.2.2 Galvanic effect on metal-disulfide oxidation ............... 85
4.2.3 Ferrolysis ...................................................................... 86
4.3 Predicting Acid Drainage Potential... ......................................... 87
4.3.1 Determination of potential acidity ............................... 87
4.3.2 Acid-base accounting ................................................... 88
4.3.3 Simulated weathering techniques ................................. 88
4.3.4 Computer simulation models ....................................... 89
CHAPTERS
ACID DRAINAGE CONTROL AND ITS LIMITATIONS .................... 95
5.1 Prevention Technologies ............................................................ 95
5.2 Alkaline Earth Carbonates .......................................................... 95
5.2.1 Coating limitations ....................................................... 103
5.2.2 Kinetic limitations ........................................................ 112
5.2.3 Placement limitations ................................................... 115
5 .2.4 Chemical equilibria limitations .................................... 117
5.2.5 Anoxic limitations ........................................................ 121
5.3 Hydrologic Influences ................................................................ 126
5.4 Bactericides ................................................................................ 127
5.5 Inundation ................................................................................... 128
5.6 Alkaline Recharge Trenches ....................................................... 129
5.7 Wetland Systems ........................................................................ 129
5.8 Organic Waste ............................................................................ 130
5.9 Macroencapsulation .................................................................... 130
5.10 Microencapsulation .................................................................... 130
PARTII
MOLECULAR CHEMISTRY OF PYRITE OXIDATION KINETICS
AND PYRITE REDOX CHEMISTRY
CHAPTER6
MECHANISMS AND KINETICS OF PYRITE OXIDATION ............... 137
6.1 Structural Chemistry ................................................................... 137
6.2 Reaction Progress Variables (RPV) ........................................... 138
6.3 Reaction Mechanisms ................................................................. 139
6.3.1 Other mechanisms of pyrite oxidation ......................... 144
6.3.2 Electrochemical mechanisms of pyrite oxidation ........ 147
6.4 Pyrite Surface Functional Groups ............................................... 148
6.4.1 Pyrite oxidation effects by iron-carbonate complexes.156
6.5 Kinetics of Pyrite Oxidation ....................................................... 159
6.5.1 Empirical pyrite oxidation rate laws ............................ 161
6.5.2 Application of pyrite oxidation kinetics ....................... 164
6.5.3 Shrinking core model kinetics ...................................... 168
6.6 Effect of Anions on Oxidation of Fe2+ ....................................... 170
CHAP1ER 7
PYRITE REDOX ClffiMIS1RY .............................................................. 173
7.1 General Information on Research Approach .............................. 173
7.2 Pyrite Stability Diagrams ............................................................ 175
7.3 Eh Measurements ....................................................................... 180
PARTlll
ROLE OF BACTERIA ON PYRITE OXIDATION
CHAP1ER8
ROLE OF BACTERIA ON PYRITE OXIDATION ................................ 185
8.1 Mechanisms of Bacterial Pyrite Oxidation ................................. 185
8.1.1 Direct metabolic oxidation ........................................... 187
8.1.2 Indirect metabolic oxidation ........................................ 188
8.2 Kinetics of Bacterially Mediated Oxidation of Fe2+ .................. 189
8.3 Michaelis-Menten Kinetics ......................................................... 193
8.3.1 Michaelis-Menten steady-state ..................................... 196
8.3.2 Michaelis-Menten rapid equilibrium ............................ 197
8.4 Surface Catalyzed Oxidation ...................................................... 200
8.4.1 Competitive inhibition ................................................. 200
8.4.2 Uncompetitive inhibition ............................................. 202
8.4.3 Competitive/uncompetitive inhibition ......................... 204
8.4.4 Experimental data ......................................................... 205
8.5 Other Microbial Processes .......................................................... 211
PART IV
ADVANCES ON PYRITE MICROENCAPSULAT ION
TECHNOLOGIES
CHAP1ER9
PHOSPHATE INFLUENCE ON PYRI'IE OXIDATION ....................... 215
9.1 A Review .................................................................................... 215
9.2 Functional Prediction Technologies ........................................... 216
9.3 Abatement Technologies ............................................................ 219
9.4 Microencapsulation .................................................................... 221
9.5 Mechanisms ................................................................................ 223
9.6 Microencapsulation .................................................................... 223
9.6.1 H202 ............................................................................. 224
9 .6.2 Phosphate ..................................................................... 226
9.6.3 EDTA ........................................................................... 228
9 .6.4 Michaelis-Men ten kinetics/application ........................ 229
9.6.5 Surface analysis ............................................................ 231
9.6.6 Effectiveness ................................................................ 235
CHAPTER 10
PRELIMINARY DATA ON PYRITE MlCROENCAPSULATION IN MINE
WASTE ..................................................................................................... 237
10.1 pH. .............................................................................................. 237
10.2 Temperature ................................................................................ 239
10.3 H202 ........................................................................................... 240
10.4 Phosphate .................................................................................... 242
10.5 Sodium Acetate (NaAC) Effect on Pyrite Oxidation ................. 244
10.6 pH, Phosphate and H202 ............................................................ 246
10.7 Coating Evaluation in Large Columns ....................................... 249
10.8 Conclusions ................................................................................ 257
PART V
SUMMARY
SUMMARY .............................................................................................. 261
REFERENCES .......................................................................................... 265
SUBJECT INDEX .................................................................................... 287
This is dedicated to my wife, Shelly, with love for her neverending
support as well as gratitude for her hel.p in proofreading the endless
documents; and to my daughter Julia and son Peter with love and
appreciation for their patience with my absent-minded preoccupation
with the writing of this book. Immense respect and gratitude go to my
late parents Peter and Glykeria Evangelou who, though they never had
the opportunity to attend formal school, gave me support and
encouragement to leave Greece at the age of eighteen to come to the
United States and pursue my dream of becoming a scientist. To the
many people in the United States who have given me support and
encouragement to fulfili my dream, I am grateful.