Sustainable Metal Extraction from Waste Streams

K. D. P. Nigam, PhD, is an Emeritus Professor at the Department of Chemical Engineering, Indian Institute of Technology Delhi, New Delhi, India and Distinguished Professor at Tecnologico de Monterrey, Nuevo León, Monterrey, Mexico.

K.K. Pant, PhD, is the Head of the Chemical Engineering Department at the Indian Institute of Technology, Delhi, India.

Perminder Jit Kaur, PhD, is a Project Scientist at the Center for Rural Development and Technology at the Indian Institute of Technology, Delhi, India.

Garima Chauhan, PhD, is working as a Post-Doctoral Fellow at the Department of Chemical & Materials Engineering at the University of Alberta, Canada.

Graphical Abstract xi

Preface xiii

1 Introduction to Sustainability and Green Chemistry 1

1.1 Introduction 1

1.2 Defining “Sustainability” 2

1.3 Dimensions of Sustainability 3

1.4 New Conceptual Frameworks to Define Sustainability 5

1.4.1 Five Dimension Framework 5

1.4.2 Four Force Model 5

1.4.3 Corporate Sustainable Management 7

1.5 Green Value Stream Mapping (GVSM) 7

1.6 “Greening the Waste” 8

1.7 Green Chemistry Terminology 10

1.8 Green Ways of Metal Extraction: Core of the Book 11

Questions 13

2 Waste Handling and Pre-treatment 15

2.1 Introduction 15

2.2 Waste Categorization 17

2.2.1 Waste Electrical and Electronic Equipment (WEEE) 17

2.2.2 Agro-Residue Waste 20

2.2.3 Industrial Waste 21

2.3 Legislations and Regulations for Hazardous Wastes 27

2.4 Handling/Management of Hazardous Waste 28

2.4.1 Secured Landfilling 29

2.4.2 Incineration 30

2.4.3 Recycling of Hazardous Waste 31

2.5 A Call for Metal Recovery from Waste 31

2.5.1 Threat to Human Health and Environment 31

2.5.2 Waste: An Artificial Ore 32

2.5.3 “Waste” to Wealth 33

2.6 Pretreatment of Waste 34

2.6.1 Disassembling the Waste 34

2.6.2 Size Reduction (Comminution) 34

2.6.3 Screening/Sieving 35

2.6.4 Classification 36

2.6.5 Segregation 36

2.6.6 Calcination and Chemical Pretreatment 37

2.7 Summary and Outlook 37

Questions 38

3 Conventional Technologies for Metal Extraction from Waste 39

3.1 Introduction 39

3.2 Pyrometallurgical Operations 40

3.2.1 Pyrometallurgical Treatment of Industrial Waste 40

3.2.2 Pyrometallurgical Treatment of WEEE 45

3.2.3 Major Challenges Associated with Pyrometallurgical Operations 49

3.3 Hydrometallurgical Treatment of Waste 50

3.3.1 Leaching of Metals in Acidic Medium 50

3.3.2 Leaching of Metals in Alkali Medium 57

3.3.3 Leaching with Lixiviants (Cyanide,Thiourea,Thiosulfate) 60

3.3.4 Halide Leaching 66

3.4 Summary and Outlook 69

Questions 70

4 Emerging Technology for Metal Extraction from Waste: I. Green Adsorption 71

4.1 Introduction 71

4.2 Adsorption 71

4.2.1 Hydrophilic Compounds 72

4.2.2 Hydrophobic Compounds 72

4.2.3 Polymer Matrix 73

4.3 Green Adsorption 74

4.4 Parameters Affecting the Adsorption Capacity of Green Adsorbents 75

4.4.1 Influence of pH 75

4.4.2 Influence of Temperature 76

4.4.3 Effect of Initial Concentration 76

4.4.4 Effect of Adsorbent Dosage 76

4.4.5 Effect of Co-ions 77

4.5 Adsorption Kinetic Models 77

4.6 Mechanism of Metal Uptake 78

4.7 Green Adsorbents: Relevant Literature 79

4.7.1 Agricultural Resources 79

4.7.2 Zeolites 81

4.7.3 Clay 84

4.7.4 Industrial Waste 85

4.7.5 Modified Biopolymers 88

4.8 Innovative Applications of Adsorption 88

4.9 Case Study 89

4.10 Summary and Outlook 90

Questions 91

5 Emerging Technologies for Extraction of Metals from Waste II. Bioleaching 93

5.1 Introduction 93

5.2 Bioleaching Process Description 94

5.3 Factors Affecting the Process Efficiency 95

5.3.1 Types of Microorganisms 95

5.3.1.1 Mesophiles 95

5.3.1.2 Thermophiles 96

5.3.1.3 Heterotrophic Microbes 97

5.3.2 Affinity Between Microorganisms and Metal Surfaces 97

5.3.3 Physicochemical Factors 98

5.3.3.1 Surface Properties 98

5.3.3.2 Oxygen and Carbon Dioxide Content 98

5.3.3.3 pH Value of Solution 99

5.3.3.4 Temperature 99

5.3.3.5 Mineral Substrate 99

5.3.3.6 Surface Chemistry of Metals 99

5.3.3.7 Surfactant and Organic Extractants 100

5.3.4 Reactor Design 100

5.4 Mechanism of Bioleaching Process 101

5.4.1 Biochemical Reaction (Direct vs. Indirect)Mechanism 102

5.4.2 Mechanism of Metal Sulfide Dissolution (Polysulfide Pathway) 103

5.5 Engineering Practices in Bioleaching Process 104

5.5.1 Batch Process 105

5.5.2 Continuous Process 106

5.5.3 Hybrid Processes 110

5.6 Application of Bioleaching in Extracting Metals from Waste 110

5.6.1 Extraction of Metals from WEEE 111

5.6.2 Extraction of Metals from Industrial Waste 115

5.6.3 Extraction of Metals from Mineral Waste 118

5.6.4 Extraction of Metals from Municipal Sewage Sludge 119

5.7 Technoeconomic Opportunities and Challenges 119

5.8 Summary and Outlook 121

Questions 122

6 Future Technology for Metal Extraction from Waste: I. Chelation Technology 123

Abbreviations 123

6.1 Introduction 123

6.2 Defining “Chelation” 124

6.3 Classification of Ligands 124

6.4 Chemistry Associated with Chelation 127

6.4.1 Theories Derived for Metal–Ligand Complexation 127

6.4.2 Attributes of Metal Ions for Complexation 129

6.4.3 Metal–Chelate Complex Formation 130

6.4.4 The Chelate Effect 132

6.5 Chelation Process for Extraction of Metals 133

6.5.1 Framework for Chelating Agent Assisted Metal Extraction from Solid Waste 133

6.5.2 Process Parameters Affecting the Metal Extraction Process 135

6.5.2.1 Effect of Reaction pH 135

6.5.2.2 Effect of Molar Concentration of Chelating Agent 138

6.5.2.3 Effect of Reaction Temperature 140

6.5.2.4 Presence of Competing Ions in Reaction Zone 141

6.5.3 Factors Affecting Stability of Metal–Ligand Complex 142

6.6 Novel Applications of Chelating Agents 143

6.6.1 Chelating Agents Used for Metal Extraction from Metal-Contaminated Soil 144

6.6.1.1 Hydrometallurgical Route of Chelation Process (Direct Use) 144

6.6.1.2 Phyto-remediation of Soils in Presence of Chelating Agents 145

6.6.2 Chelating Agents Used for Metal Extraction from Industrial Waste 147

6.6.3 Chelating Agents Used for Metal Extraction from WEEE 149

6.7 Ecotoxicological Concerns and Biodegradability 151

6.8 Summary and Outlook 155

Questions 155

7 Future Technology for Metal Extraction from Waste: II. Ionic Liquids 157

Abbreviation 157

7.1 Introduction 158

7.2 What Are Ionic Liquids? 158

7.3 Characteristic Properties of Ionic Liquids 161

7.3.1 Melting Point 162

7.3.2 Vapor Pressure and Nonflammability 162

7.3.3 Thermal Stability 163

7.3.4 Density 164

7.3.5 Viscosity 164

7.3.6 Polarity 166

7.3.7 Coordination Ability 166

7.3.8 Conductivity 167

7.3.9 Solubility 167

7.4 Classification of Ionic Liquids 169

7.5 Environmental Scrutiny of Ionic Liquids 171

7.6 Applications of Ionic Liquids 173

7.6.1 Extraction of Metals from Aqueous Media 173

7.6.2 Extraction of Metals from Industrial Solid Waste/Ores 176

7.6.3 Extraction of Metals from WEEE 177

7.7 Summary and Outlook 179

Questions 179

8 Scale-up Process for Metal Extraction from Solid Waste 181

Nomenclature 181

8.1 Introduction 182

8.2 Process Intensification 183

8.3 Intensification of Metal Extraction Processes 185

8.3.1 Centrifugation 185

8.3.2 Liquid–Liquid Extraction 185

8.3.3 Mixing 186

8.3.4 Reactors 188

8.3.5 Comminution 188

8.3.6 Drying 189

8.4 Scaling Up from Batch to Continuous Process 189

8.4.1 Process Design Fabrication 190

8.4.2 Designing of Pilot Plant 191

8.4.2.1 Material Balance 191

8.4.2.2 Development of Comminution Circuit 193

8.4.3 Reactor Sizing and Agitator Selection 197

8.4.4 Design of Filtration System 199

8.4.5 Design of Heat Exchanger 201

8.4.6 Design of Precipitator Unit 202

8.4.7 Batch Scheduling 203

8.5 Summary and Outlook 204

Questions 205

9 Process Intensification for Micro-flow Extraction: Batch to Continuous Process 207
Jogender Singh, Loveleen Sharma, and Jamal Chaouki

Abbreviations 207

9.1 Introduction 208

9.2 Miniaturized Extraction Devices 208

9.2.1 Intensification in Miniaturized Extraction Devices 209

9.2.2 Application of Miniaturized Extraction Devices 211

9.3 CFI for Continuous Micro-flow Extraction 212

9.3.1 Designing CFI as an Extractor 216

9.3.2 Extraction Parameters 218

9.3.3 Methodology and Setup for Micro-flow Extraction 218

9.3.4 Liquid–Liquid Micro-flow Extraction 220

9.3.4.1 Typical Flow Patterns 220

9.3.4.2 Extraction Efficiency 222

9.3.4.3 Effect of Aqueous Phase Volume Fractions on Extraction Efficiency 223

9.3.5 Micro-flow Extraction of Co and Ni 225

9.3.5.1 Effect of pH 225

9.3.5.2 Effect of Residence Time 225

9.3.5.3 Effect of Extractant Concentration 229

9.4 Summary and Future Challenges 229

Questions 229

Bibliography 231

Index 273

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