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© University of Pretoria
© University of Pretoria
CONTENTS Page
Section Title
1
INTRODUCTION
1
2
HISTORICAL BACKGROUND AND RELATED RESEARCH
Historical perspective
International perspective
South African perspective
5
5
5
8
2.1 2.2 2.3 3
3.1 3.2 3.3 11 11 12 3.4 3.5 3.6 ACID MINE DRAINAGE
An introduction to acid mine drainage
Sources of acid mine drainage
Chemical and biological reactions related to acid generation
Rate of acid generation
Case studies
Mine planning and acid generation
14 16 17 17 4
4.1 4.2 4.3 4.4 4.5 4.6 4.7 THE STUDY AREA
Geology
Climate
Topography and drainage
Agriculture
Urban development
Coal mining activity
Power generation
19 20 22 26 26 26 27 27 5
5.1 5.1.1 5.1.2 5.1.3 5.1.4 5.1.5 5.1.6 5.1.7 5.1.8 5.1.9 5.1.10 5.2 5.2.1 5.2.2 5.3 COAL
General
Mining methods
Coal preparation
Transport and storage
Uses of coal
Coal in the environment
Clean coal technologies
Rehabilitation
Safety
The future
Economic implications
Coal characterisation
Proximate analysis
Ash analysis
Coal in the study area
28 28 29 30 30 31 33 33 34 35 35 35 37 37 38 39 6
6.1 WATER
Characterisation of waters
41 41 6.1.1
6.1.2
6.1.3
6.1.4
6.2
Chemical equilibria, pH and buffers Physical tests Principles of analytical chemical methods Solids determination Water use in the coal mining industry 42 43 44 44 45 7
7.1
7.1.1
7.1.2
7.2
7.2.1
7.2.2
METHODS OF INVESTIGATION Sampling GIS maps Collection of samples for chemical leaching studies
Analysis Presentation of data by means of GIS Chemical leaching studies 46 46 46 47 47 47 48 8
8.1 8.2 8.3 DISCUSSION OF RESULTS GIS map - database results
Results of beaker tests
Discussion
50 9
67 9.4 9.4.1 9.4.1.1 9.4.1.2 9.4.1.3 PREVENTION, PREDICTION, MANAGEMENT AND
TREATMENT Prevention mechanisms
Prediction techniques
Statistic testing
Kinetic testing
Management strategies
Mineral and mining management
Water management
Waste management
Standards and guidelines
Control of acid generation
Control of acid migration
Management design criteria
The design process
Modelling
Water quality management objectives
Future management options for the Witbank and Middelburg Dam catchments
Treatment technologies
Process development and testwork procedure
Characterisation of feed
Testing
Case studies
10 CONCLUSION
9.1 9.2 9.2.1 9.2.2 9.3 9.3.1 9.3.2 9.3.3 9.3.4 9.3.5 9.3.6 9.3.7 9.3.7.1 9.3.7.2 9.3.8 9.3.9 APPENDIX A
A.1
A.2
A.2.1
WATER QUALITY GUIDELINES Water quality databases South African water quality guidelines Domestic use: Volume 1 50 57 59 67 68 68 69 69 70 72 74 74 75 76 76 77 78 78 80 80 86 87 87 88 89 91 91 99 99 A.2.2
A.2.3
A.2.4
A.2.5
A.2.6
A.2.7
Recreational use: Volume 2 Industrial use: Volume 3 Agricultural use - Irrigation: Volume 4 Agricultural use - Livestock watering: Volume 5
Agricultural use - Aquaculture: Volume 6 Aquatic ecosystems: Volume 7 103 104 105 107 109 112 APPENDIX B
B.1
B.2
B.3
B.4 B.5 TABULATED RESULTS OF BEAKER TESTS
pH Sulphates Alkalinity Acidity
Iron (1/)
114 114 115 116 117 118 APPENDIX C GRAPHICAL PRESENTATION OF RESULTS OF BEAKER TESTS
pH
Sulphates
Alkalinity
Acidity
Iron(lI)
119 119 125 125 135 138 C.1 C.2 C.3 C.4 C.5 LIST OF FIGURES Figure Title
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
Location of the study area
Energy sources in the South African economy in 1996
Collieries in Mpumalanga Province
Schematic representation of geology in the study area
Contribution of seam to in situ demonstrated coal resources
Mean annual wind speed, frequency and direction
Metamorphism of organic matter as it increases in rank from peat to anthracite
Mining method as a function of seam thickness and mining depth
Scheme showing the likely stages of environmental pollution in the production of coal
The marginal social costs (MSC) and marginal social benefits (MSB) of pollution
An alternative representation of the marginal social costs (MSC) and marginal social benefits (MSB) of pollution
Location of database sample sites in the study area, showing the summary data provided by activating the site icon for Greenside Colliery
Fixed Carbon % vs water quality
Pyrite % vs water quality
Ash % vs water quality
Total Sulphur % vs water quality
Mining method vs water quality
Location of sample sites used for chemical analysis
Summary of all samples: pH over time
Summary of 'grab' samples: Alkalinity over time
Summary of discard samples: Alkalinity over time
Summary of product samples: Alkalinity over time
Summary of 'grab' samples: Acidity over time
Summary of discard samples: Acidity over time
Summary of product samples: Acidity over time
The design process Page
3
9
19 20 21 24 28 30 32 36 37 51 52 53 54 55 56 58 60 61
62
63
64
65
66
77
UST OF TABLES TABLE
TITLE
1
2
3
World recoverable hard coal reserves 1996
Coal consumption in the domestic market in 1995
Average rainfall per month, over a 10 year period from
1989 to 1999
Average monthly minimum and maximum
temperatures over a 10 year period from 1989 to 1999
Average monthly evaporation over a 10 year period
from 1989 to 1999
Characteristics of coal in the study area
4
5
6
PAGE
8
9
22
23
25
39
ABSTRACT The coal minIng and power generating industries of the Witbank and
Middelburg Dam catchments in South Africa's Mpumalanga Province have
received much criticism for their apparent apathy regarding water quality in
the area. Although a number of previous studies have proved that several of
the coal mines and power stations are directly responsible for point and
diffuse discharges of acid leachate into the local water bodies, the limited
case study conducted for the purpose of this thesis did not produce results
that can be used to effectively describe a situation that gives cause for
concern. The results do however display a number of trends:
• Coal 'grab' samples are likely to produce the most acid leachate
• Coal product samples are most likely to generate more alkaline leachate
• GIS maps are a commendable method of correlating a range of
information contained in a number of databases and provide a user­
friendly, interactive means to access a wide range of data at once
In order to meet the water quality management objectives of the catchment
management forums, it will be necessary for all coal mines and power
generation facilities in the area to come together and develop the most
suitable water management programme to ensure that acid mine drainage
does not render the regional water resources unfit for any use.
It is also important to be aware that the new National Water Act and
associated environmental and mining laws discussed in this thesis are
comparable with the highest standards internationally. At the same time, one
must always include the factor of human well-being in the scope of the
definition of the environment so as to ensure that opportunity is provided for
the greatest benefit to be awarded to all components of both the natural and
built environments.
ACKNOWLEDGEMENTS
Special thanks must be extended to the following persons for their
contributions in terms of advice and support:
Dr Jannie Maree, Environmentek, CSIR
Calie Adlem, Environmentek, CSIR
Pieter Pretorius, Environmental Management Services, Iscor
Elana Macdonald, Geology, Iscor
Johan de Korte, SABS laboratory
Marie Coetzee,SABS laboratory
Fritz Bekker, Clean Stream Environmental Consultants
Prof van Schalkwyk, University of Pretoria
Prof Snyman, University of Pretoria
Dr van Rooy, University of Pretoria
My parents and friends
"He who aims for the moon,
May hit the top of the tree;
But he who aims for the tree,
May never get off the ground."
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