Waste Production and Utilization in the Metal

Extraction Industry

Sehliselo Ndlovu, Geoffrey S. Simate, and Elias Matinde

~ ~~r?F!~~Z;up ~ BocaRaton London NewYori< CRC Press ls an lmprlnt of the Taylor & Francis Group, an lnfonna business

Contents

. ce-................... „ ••••••••••• „ ••••••••••••••••••••• „ ••••••••••••••••••••••• „.„.~ .. ," .•. „ ••••••••••••••••• J„ •••• „ ••••••• „ • •••••••••••••••••• xv Authors ................................. „ ..................................................................................................... xvii

1. Overview ......... „ ............ „ .... „ ............ „ ........... „ ........................................................................ 1 1.1 Introduction ................ „ .... „ ................... „ ....................... _ ............................ „ ............... l 1.2 Legislation and Impacts of Mining and Metallurgical Waste ................................. 1

1.2.1 Legislation and Policies„„„„„ .... „„„ .... „„ .....•. „ .................................. „.„.„„ .. 1 1.2.2 Environmental and Health Impacts of Mining and Metallurgical Waste ...... 2

1.3 Mining and Beneficiation Waste Production and Utilization ................................ .4 1.3.1 Mine Overburden and Waste Rock „„ .... „.„„ ............ „ ...................... „„„ ...... 4 1.3.2 Mineral Beneficiation Waste ....... „ ...... „ ....................................... „ ....... „ ........ 5 1.3.3 Acid Mine Drainage .„ ...... „ ........ „ ....... „ ....... „ ........ „ ....................................... 5

1.4 Ferrous Metals Waste Production and Utilization „ .... „ .......................... „ ............... 5 1.5 Ferroalloys Waste Production and Utilization .. „ ........ „ .................... „.„ ................... 6 1.6 Base Metals Waste Production and Utilization ..... „„ ........ „ ...................... „ .............. 7 1.7 Hydrometallurgical Waste Production and Utilization ................. „ ........................ 8

1.7.1 Production of Copper ... „ .. „ ........ „ .................. „ ....... „.„„ .. „ .. „„ .. „„„ ............... 8 1.7.2 Production of Zinc ............. „ .................. „ .................... „ .................................. 9 1.7.3 Production of ,Alumina ........... „, .............................. „ .•.....•............................ 10 1.7.4 Production of Precious Metals ....................... „ ............ „ .... „ .... „ ............. „.„10 1.7.5 Production of Strategie and Critical Metals .„ ... „ .......... „.„„ .............. „ ...... 11

1.8 Metal Manufacturing and Finishing Waste Production and Utilization ............ 11 1.9 Post-Consumer Waste Production and Utilization .„ ............... „ ......................... „.12 1.10 Conclusions and Future Outlook ................ „„ ............ , ..... „ .......... „„ ........................ 12 References ......................... „ ....................... „ ..... „ .. „ .... „ ... „.„„ ................. „ ........ „ ................ „. 13

2. Legislation and Policies Goveming the Environmental and Health Impacts of Metallic Waste .„ ................................................................................................ 19 2.1 Introduction „ .... „ .. „„ ........ „.„ .... „ ................................................ „ .............................. 19 2.2 Legislation and Policies-„„-......• „ ...•. _, .• „„„ .•... ,.. .• ,„ ...... „ .......... „ ............ „„ .............. 21

2.2.1 ISO 14000 Environmental Management System .............................. „ ....... 21 2.2.2 Analysis of Legislation and Polici~.„ ....... „.„„ •. „ .......•............ „ .............. „.24

2.2.2.1 United States of America .................••• „ .... ,„ ... „ ............................. 24 2.2.2.2 European Union ............................................................................. 24 2.2.2.3 Australia .............. „ .......................................................................... 24 2.2.2.4 South Africa ... „ •... „ ... „_ ... „„, ... „.„„.„„„ .. „ .• „ .. _.„ ...... „„ .... „„„ ....... 27 2.2.2.5 China „„ .......................................................... „ ................................ 27 2.2.2.6 India ........................ „ ....... „.„ ....................... „ ......... „„ .. „„ ............... 28

2.2.3 Guidelines for Managing Mining and Metallurgical Waste .................... 29 2.2.3.1 Waste Rock .... „ ..... „ ...... „ ............... „ ........................ „ ................ „ .. „30 2.2.3.2 Tailings ............ „„ .. „ .... „„ ............ „ ..... „ .... „ ...... „„„„„ „ ............ „.„.„ 30 2.2.3.3 Slag ...... „ .... „ .. „„„ .... „ ............. „.„ ... „„ ... „ ............. „„ ..... „„.„ .. „„ .. „ .. 32 2.2.3.4 Sludge .... „„„„„.„ .. „ .......... „ ... „.„.„„„ ... „.„ .... „„ .. „„„„ ........ „ ...... „ .. 32 2.2.3.5 Air Emissions „ .. „ ........................ „ .......................... „ .. „„ .. „„ „ ..•••••• 35

V

vi Conren~

2.3 Environmental and Health Impacts .„ .... „ .... „„.„ ..... „.„ .. „„„.„ .... „„.,.„.t-···„ .• „„ .. -.36 2.3.1 Leachates„„ ... „„.„„ .. „„ .. „.„ ... „„„ ... „ .. „„„.„„„„.„.„„„„.„.„„.„„„„.„„.„„„.„.37

2.3.1.1 Lead.„.„„„.„„„„.„„ .. „ .. „„.„ .... „ .. „.„„„„.„„ .. „.„„„„.„ .. „„.„„„„.„ ... 37 2.3.1.2 Mercury„„„.„.„„„„.„.„„.„„„.„.„„„ .. „„„„„„.„ .. „„„„„„.„.„.„„„„„.38 2.3.1.3 Cachnium.„ .. „„„ ... „„.„„„„„ .. „„.„ .. „.„„ .. „.„„„„„ ... „„„„.„„.„„„„„39 2.3.1.4 Chromium „„.„.„„„.„„„„„.„„„„„ .. „„„„„„ .. „„ .. „„„„.„.„„„„„„„ ... 39 2.3.1.5 Zinc„„ .. „ .. „„.„ .... „ ...•..... „.„,„ ........ „ ... „ ... „.„„„„ ... „ .. „„ .... „ .. „„ .... „ .. 40 2.3.1.6 Arsenic „ .. „ .. „„„„.„.„.„.„.„„„„.„.„.„.„ ... „„„ ... „.„„„„„„„„ .. „ .. „„ ... 40

2.3.2 Particulate Matter „„.„.„ .. „„.„„„„„ .. „„„„„„.„„„.„„„„ ... „„„ .. „„ .. „ .. „„„ ... „.42 2.3.2.1 Silica „„„.„.„„„ .. „ .. „„.„.„„ ... „„„.„.„„„„„„.:.„:„„„„.„„„.„.„„„ .. „„„45 2.3.2.2 Asbestos .. „„.„.„„„„„„ ... „„„.„„„„„ .•. „.„ .. ~·„.:„„„„„„„„„„„„„ .. „„ .. 47 2.3.2.3 Coal Dust„„„„„„„„„.„.„„.„„„„„„„„„„„.„ .. „.„„.„„„„„.„.„ .. „„ ... „49 2.3.2.4 Smelter Dust„1 ..• „.-.. „ .. „ .•. „„„.„„. „„„„ ... „.-.„.„„„„„„„ ... „„ .. „„.50

2.3.3 Gaseous Emissions „.„„„ .. „„„.„„.„„„„„„„„„„.„„„.„.„„„ .. „„„„ .. „.„.„„„„ .. 52 2.3.4 Wastewater and Effluent„„.„„„„„.„.„„.„.„„„„ ... „ .... „„„„„„„„„„.„.„„„„„.52 2.3.5 Other Mining and Metallurgical Effects „.„ .. „„„„„„„„„„ .• „„„„„„„.„„.„„ 52

2.4 Concluding Remarks ..... „ .......... „ ... „ .. „„„ .... „„„„ ...... „„ ........ „.: .. „ .... „: ... „„.„.„„ .... „55 References .... „.„.„.„„.„.„„ .. „ .... : .......•.... „ ........ „ ..... „ .... „„ .. „ .... „.„„„„ •. „„ .. „„.!„ ... „„.„ ... „ .. „ 56

3. Mining and Beneficiation Waste Production and Utilization.„„„.„„„„.„.„.„.„„.„.„„65 3.1 Introduction .„„ .. „.„.„ .•. „„„„„„.„„ ..... „„.„.„ .... „„.„ .... „„„.„.„ .. „.„.„„„„„„ .. „ .. „„„„„ 65 3.2 Mine Overburden and Waste Rock „„„.„„„„.„„„.„ .. „„„„.„„„.„ .. „ .. „„ ... „„„„„„„„65 3.3 Mineral Beneficiation Waste .... „.„„„„ .. „„.„.„ .... „ .... „ .. „ .. „„ .. „ .. „„.„.„.„ .. „„„ .... „„„ 66

3.3.1 Mineral Beneficiation Methods and Techniques .. „.„.„„„„ ... „„„.„„„.„„„ 66 3.3.1.1 Comminution„.„„„„„„„„„„.„ .. „„ .. „.„„.„.„.„ ... „„„„„„.„„„„„„.„.66

3.3.2 Characterizanon of '!failingS-„„„„ .. „„.„.„„„„„„„„„ .. „„ .. „„„„.„„ ... „„„„.„.„ 72 3.3.3 Potential Utilization of Tailings „.„„„.„.„.„„ .. „„„„.„„ .. „.„ .. „„„„„„„„.„„„ 73

3.3.3. l Reprocessing of Tailings for Metal Recovery .„.„„„.„.„ .. „.„„ .. „ 7 4 3.3.3.2 Reprocessing of Copper 'Thilings.:.„ ... „„„„„ .. „„„.„„„„„.„„„„„„ 75 3.3.3.3 Reprocessing of Gold Tailings for Metal Recovery „„.„„„„„ .. „ 77 3.3.3.4 Reprocessing of Iron Thilings„„.„„„.„„„„„„„.„.„„„„.„„.„„„„„„ 78 3.3.3.5 Reprocessing of Chrome Tailings for PGMs

and Chrome Recovery „„„„„„.„„.,„„„.„ ... „.„.„„„„„„„.„ .. „„„ .. „. 80 3.3.3.6 Tailings Utilization in the Construction Industry„„„„.„.„„.„„.81 3.3.3.7 Tailings Utilization in Brick Making„.„„„„„.„ .. „„.„„.„„„.„„„.„83 3.3.3.8 Other Potential Applications „„.„„„ .. „ .. „„„„„„.„.„„„„„„.„.„„„. 87

3.3.4 Summary .„ .. „ .... „ ...• „ ........ „„ .......... „ ..................... „ ............................. „ ........ 88 3.4 Acid Mine Drainage„.„ .. „„„„.„„ .. „„.„.„„ .. „ ...... „.„ .. „.„:.„ .. „.„ ...... „ .. „ .. „ ... „.„.„ .. „ .. 89

3.4.1 Formation of Acid Mine Drainage „.„„„„„.„ ... „„„.„„„ .. „ ... „.„„„ .... „„„ .. „89 3.4.2 Prevention and Mitigation of Acid Mine Drainage „„.„.„„„.„.„„„.„„.„„ 91

3.4.2.1 Source Control Techniques „„„„„„„„.„„„„„ ... „.„„.„ ... „„ .. „„„.„„ 92 3.4.2.2 Migration Control and/Treahnent Methods„„.„„„.„„.„„.„.„.„ 93

3.4.3 Opportunities in Acid Mine Drainage .. „.„„„„„„„„.„.„„ .... „„.„.„.„„ .. „.„. 96 3.4.3.1 Recovery of Metals .. „ ... „ .. „ ..• „„„„ .. „.„.„ ... „„„.„„„.„„„ .. „„„„„.„. 96 3.4.3.2 Recovery of Water „.„„.„„.„.„.„„„„„„ .. „„„ ... „ .... „.„„ .. „.„.„ .. „.„„ 98 3.4.3.3 Recovery of Sulphuric Acid „ .. „ .. „ .. „„„ .. „.„„.„„„.„„„ ... „.„„ .. „.„ 99 3.4.3.4 Uses of AMD Treatment Sludge„ ... „„„.„ .. „ .. „ .. „„„„„„.„„„„.„.101

3.5 Concluding Remarks .„„.„ .. „ ... „ .. „ .. „ .. „ .. „„„„„ .. „„„„.:„.„.„„ .• „„.„.„.„.„.„ ... „„„„.102 References •........ „„ .. „ .... „„.„.· .... „ .... „„„ ............. „ ... „ ... ,„ .. „ ........ „ .. „ ... ; •........... „.„.„ .. „ ........ 103

Contents vii

4. Ferrous Metals Waste Production and Recycling ....... „ .. „ ............................................ 113 4.1 Introduction ............................................................................................................... 113 4.2 Production of Iron and Steel. .............................................•..... „ •...•....••...•.•....•........ 114

4.2.1 Blast Fumace Ironmaking Process ............................................................ 115 4.2.1.1 Physicochemical Functions of the Blast Fumace ..................... 118 4.2.1.2 Raw Materials for the Blast Fumace ...... „„„ .............. „ ........... „. 119 4.2.1.3 Iron Ores .................................................. „ .................................... 119 4.2.1.4 Blast Fumace Sinter ................... „ ........................................ „ ....... 119 4.2.1.5 Blast Fumace Pellets .... „.„ .............. „ ... „ ............................... „.„ .. 121 4.2.1.6 Metallurgical Coke ..................... „.„ ........................ „ .... „„ ........... 121 4.2.1.7 Carbon Composite Agglomerates and Ferro-Cokes .„ ..... „ ..... 124 4.2.1.8 Resource Constraints in the lron and Steelmaking Process „.124

4.2.2 Alternative Ironmaking Processes .................................. „ ......................... 125 4.2.2.1 Direct Reduction Ironmaking Processes „„.„„ ........ „.„.„„„ .... „126 4.2.2.2 Direct Smelting Reduction Processes ................ „.„ .. „ .......... „ ... 127

4.2.3 Electric Are Steelmaking Processes „ ............... „.„„ ................................. „ 129 4.2.4 Basic Oxygen Steelmaking Process ........... „ ................................ „ ............ 130 4.2.5 Stainless Steel Refining Processes ......... „„ ...... „„„„„ ............................ „ ... 131 4.2.6 Solidification and Casting of Steel„„„„ ... „ .... „„ .• „ .. „„ .. „.„„ .... „„ ........... „134

4.3 Refractory Materials in the lron and Steelmaking Process „.„ .. „ ....... „„„„ ......... 136 4.3.1 General Considerations ................. „„ .......... „„ ................... „ .. „ ................... 136 4.3.2 Classification of Refractory Materials„ ............. „ ... „.„ ................ „ .......... „136

4.4 Overview of Waste Generation in the lron and Steelmaking Processes „„ .... „.140 4.5 Categories of Metallurgical Wastes Generated in Iron and Steelmaking

Unit Process „ •....... „ .. „„ .. „ .......... „ ..•..... „ .... „ •.•. „ .. „„ ................ „„ .. „ ........ „„„ ........... 142 4.5.1 Metallurgical Dusts and Sludge ....... „ .... „ ....... „„ .. „ ..... „.„„ .. - ..... „ .. „.„.„ .. 142

4.5.1.1 Generation of Particulate Dust from the Coke Production Process .............. „ ............................................................. „ ..... „„ .... 142

4.5.1.2 Generation of Dust from the Raw Material Agglomeration Processes ..... „ ....•.............•.•. „ .............. „ ...... „ ..... 144

4.5.1.3 Particulate Dust Generation from lron and Steel Unit Processes„ ...... „ .. „ ........ „ ......................................•......... „„ ........ „ .. 146

4.5.2 Iron and Steelmaking Slags „.„ ..... „ .... „ .. „„„ ........ „„„„ ... „.„„„„ ... „.„.„„ ... 154 4.5.2.1 Functions and Properties of Slags.„.~„„ ... „„„ ....... -.„„„.„ ... „ .. 154 4.5.2.2 Blast Fumace S g& •. „ ..• „.„.„ ...... „.„„ ..... „„.„ ... „ ... „„ .... „.„ .. „ ... „. 156 4.5.2.3 Steelmaking Slagst.„„„ •.•• - ....... '""-·"······„-···--··-········„·····„··········· 157

4.6 Recycling and Reuse of lron and Steelmaking Wastes ... „ ...... „„.„„ .... „ .... „„ .. „„161 4.6.1 Recycling and Reuse of Raw Materials Agglomeration Dusts

and Sludges .............•.... „ ..... „ .. „ ..... „ •••••••••.• „ •. „ .. „ .. „„„.„.„ .......................... 162 4.6.2 Recycling and Reuse of Blast Fumace Irortmaking Dusts and Sludges.„. 164 4.6.3 Recycling and Reuse of Blast Furnace Ironmaking Slags „ .. „ .... „.„„„ ... 165

4.6.3.1 Granulated Blast Furnace Slags as Construction Materials ... 165 4.6.3.2 Granulated Blast Furnace Slags as Adsorbent Materials ..... „. 166 4.6.3.3 Granulated Blast Furnace Slags as Geopolymeric

Materials .... „ „ ... . „„ .. ... „ ... . . . „ .•.. .. „ ............. „ . .. ........ .................... „ . 166 4.6.3.4 Slow-Cooled Blast Fumace Slags •.• „„ .. „„.„„„.„ .. „„„„ ..... „ ..... „ 166

4.6.4 Recycling and Reuse of Steelmaking Dusts and Sludges „.„„„.„„„ .... „16687

4.6.4.1 Direct Reduction Processing of Agglomerated Dust „„.„ ....... 1 4.6.4.2 Smelting Reduction Processing of Steelmaking Dust„„.„„„ .. 171

viii

4.6.5

4.6.6 4.6.7

4.6.8

4.6.9 4.6.10

Contents

Plasma-Based Processing of Steelmaking Dusts ..... „ .............................. 172 4.6.5.l Fundarnentals of Thermal Plasma Processing .„„„„„„.„„„„„.172 Hydrometallurgical Processing of Steelmaking Dusts„.„.„„.„„„„„.„„.174 Solidification and Stabilization (S/S) of Steelmaking Dusts „„„„„.„„„177 4.6. 7.1 Fundarnentals of Waste Stabilization and Solidification „„„„178 4.6.7.2 Solidification „„„„„„„„.„„„.„.„.„„.„ ... „„.„„.„„„„„.„.„„„„„„„„.178 4.6.7.3 Stabilization .. „ •..•.• „ ..... „ ... „ ... -··-·'···········•·„ ... „„ ........ „„ .. „ .... „ ... 178 4.6.7.4 Stabilization and Solidification of Steelmaking Wastes

Using Cementitious Systems „„„„„„.„„„.„„„„.„.„„„„„.„„„„„.179 4.6.7.5 Stabilization of Steelmaking Waste Using Geopolymer

Systems ..... „ ..... „„.„ .... „ .... „ ................ „ .... „ .... „ .. „„ ..... „ ......... „ ..... 179 4.6.7.6 Thermal Vitrification of Steelmaking Dusts„„.„„.„„„.„„„ .. „„ 181 Recycling and Reuse of Steelmaking Slags „.„„„„„.„„„.„.„ .. „„.„„.„ .. „„183 4.6.8.1 Electric Are, Basic Oxygen and Ladle Fumace Slags „„„„„„„ 183 4.6.8.2 Recovery of Entrained Metallic Elements from

Steelmaking Slags .. „ ••.•.. „„ .. „„ •. - ... „ ................. „ .... _ ...... „.„.„ .. 184 4.6.8.3 Utilization of Steelmaking Slags as Construction

Materials „„ ..... „ ..... „ .... „ ............ „ ..... „ ............ „ .......... „„ .. „ ........... 185 Recycling and Reuse of Continuous Casting Slags„„„ .. „.„ .. „ ...• „„„„„„ 187 Recycling and Reuse of lron and Steelmaking Refractory Materials „.187 4.6.10.1 Classification of Spent Refractory Materials .„„.„„„„„„„„„„ .. 188 4.6.10.2 Overview of Current Refractory Materials Recycling and

Reuse Practices ..... „.„ ...... - .• „ ............. „ ......... „ .....• „ .. „ •.•.. „ .. „ .... „.189 4.6.10.3 Fundamentals of Slag Foaming Practice ... „ .. „ .. „.„ .. „ ........ „„„.190

4.7 Trends and Challenges to Waste Reduction in the Iron and Steelmaking Process .................. „.„ ..... „ .. „ ......... „ ............ „.„ ..................... „„ .. „„.„.„„.„ .. „ .... „„ .... 191

4.8 Concluding Remarks.„.„.„„„„„„.„.„„ .. „„„„ ... „„„.„„ .. „ .. „„ .. „„„ .. „„„.„„„„„„„„ .. 192 References .„ .. „„„ ..... „ .......... „„„ .. „„.„ ..... „ ... „ .. „ .. -.„ .. „„ .... „„ .. „ ........ „„ ..... „„„ ............... „.195

5. Ferroalloys Waste Production and Utilization „.„„„.„„.„.„„„„„„„„„.„„„„„„.„„„„„„209 5.1 Introduction ... „„„.„„„„„„„„„„„„ ....... „„„ .... „ ... „.„„„„.„.„ ..... „„„„„„„„„„„„„ ....... 209 5.2 Ferroalloys Production Processes „.„.„„„„„„.„„„„ .. „„„„„.„ ... „„„.„ .. „„„„ .. „„ .. „.210

5.2.1 Introduction „„„„„„.„„„ .. „.„„„„„„.„ .. „„ ..... „ .. „„„„.„„„.„.„„„„„.„ ..... „.„ .. 210 5.2.2 Production of Bulk Ferroalloys „„.„.„„„„„„„„„.„.„„„„.„„„„„„„„„„ .. „ ... 210 5.2.3 Production of Noble Ferroalloys „„„„„„„„„„.„„„„„„„„„.„ ... „.„„„„„„.„ 211 5.2.4 Overview of Waste Production in Ferroalloys Industry „.„„„„„„„„„„.212

5.3 Production of Chromium and Its Alloys „„„„„„„.„„.„„„„.„„„„.„„„.„„.„„„„„„.213 5.3.1 Chemical and P.h.ysical Properties of Chromium„„„.„.„„ .... „.„.„„„„„ .. 213 5.3.2 Industrial Uses of Chromium „„„.„„„„„„.„„,.„.„„„„„„.„„.„„„„„„„.„.„.214

5.3.2.1 Metallurgical Uses of Chromium as an Alloying Element..„. 214 5.3.2.2 Chromium Uses in High-Temperature Refractory

Materials „„„ .... „„.„.„.„.„.„.„„ ..... „.„„„„„ .. „„.„„„„„„ .... „„„„„„.216 5.3.2.3 Chromium Uses in Chemicals Industry.„„.„ .. „„.„„ ... „„.„„„„.216

5.3.3 Occurrence of Chromium„„„„„„„„„„„„„.„.„„„.„„„ ... „„„„ .. „.„.„„ .. „„ ... 217 5.3.4 Beneficiation of Chromite Ores..„ ...•. „~ ...... „ ......•. „.„ ... „„„„„„„.„„ .... „„„„ 218

5.3.4.1 Agglomeration of Chromite Ore Fines„ .. „„„.„„.„.„ ... „„„„„.„. 219 5.3.5 Smelting of Chromite Ores „ .. „„.„.„ .. „ ... „„ ...... „„ ... „ ... „ ...... „.„ ...... „ .. „ .. „. 220

5.3.5.1 Carbothermic Reduction of Chromite Ores„ ... „„„.„„.„„„ .... „.221 5.3.5.2 Classification of Ferrochromium Alloys „„„„.„„„.„.„„„„„„.„. 223

Contents ix

5.3.5.3 High-Carbon Ferrochromium Alloys ................ „ ........... „ ......... 223 5.3.5.4 Medium-Carbon Ferrochromium Alloys.„ ... --·····-·················· 225 5.3.5.5 Low-Carbon Ferrochromium Alloys ......................................... 227

5.3.6 Waste Generation in Ferrochromium Production Processes ................. 228 5.3.6.1 Particulate Dust Emissions in the Production of

Ferrochromium Alloys ................................................................ 228 5.3.6.2 Particulate Dusts from the Agglomeration Processes of

Chromite Ores •..........................•................................................... 229 5.3.6.3 Particulate Dust Emission from Smelting of Chromite Ores ..... 230

5.3.7 Recycling and Utilization of Ferrochromium Smelter Particulate Dusts .............................................................................................................. 233 5.3.7.1 Metal Recovery and Recycling of Ferrochromium

Smelter Dusts ........................ „ .•.••••...•••••...•••••••....••..• „ ••••••.••••••.•••• 234 5.3.7.2 Stabilization and/ or Solidification of Ferrochromium

Smelter Dusts ................................................................................ 235 5.3.8 Physicochemical Characteristics of Ferrochromium Alloy Slags .......... 236

5.3.8.1 Mineralogical Phases of Ferrochromium Alloy Slags ............. 237 5.3.9 Recycling and Reuse of Ferrochromium Alloy Slags ............................. 238

5.3.9.1 Factors Affecting Chromium Losses to Slag; ........•................... 238 5.3.9.2 Metal Recovery from Ferrochromium Smelter Slags .............. 239 5.3.9.3 Stabilization of Chromium Using Engineered Slag Properties .... 240 5.3.9.4 Reuse of Ferrochromium Smelter Slags as Construction

Materials ........................................................................................ 243 5.3.9.5 Summary ....................................................................................... 243

5.4 Production of Manganese and ltsAlloys.-·-·---······--'····-·······--··········--·····"·····244 5.4.1 Chemical and Physical Properties of Manganese ................................... 244 5.4.2 Uses of Manganese and Its Alloys •............ - .............•....•.............. „ ........... 244

5.4.2.1 Metallurgical Uses of Manganese as an Alloying Element.. .. 244 5.4.2.2 Uses of Manganese in Chemicals Industry ... „ ......................... 245

5.4.3 Occurrence of Manganese .. ·-····-··"············································-···········-· 245 5.4.4 Beneficiation of Manganese Ores ..... „ ...................•........... „ ..•••••••••• „ ••••••.• 247

5.4.4.1 Agglomeration of Manganese Ore Fines ........................... „.„ .. 247 5.4.5 Production of Manganese Alloy.s..„1 ..... „„.„ ..... „ ...•.•. „.„ ...•...•. „.--··········· 248

5.4.5.1 High-Carbon Ferromanganese Alloys .„ ... „ „ .............. „ •.....••.•.. 249 5.4.5.2 Silicomanganese Alloys ............................................................... 251 5.4.5.3 Medium-Carbon Ferromanganese Alloys ................................ 252 5.4.5.4 Silicothermic Reduction ............................... „ ................ ... .......... 252 5.4.5.5 Converter Decarburization Process .............. .................... „ ....... 253

5.4.6 Waste Generation in the Production of Manganese Ferroalloys ........... 254 5.4.6.1 Particulate Dust Emissions in Production of Manganese

Ferroalloys ·~········-······-···--···-........... „ ......... „ ............................. 254 5.4.6.2 Physicochemical Properties of Particulate Dusts .................... 255 5.4.6.3 In-Process Recycling of Ferromanganese Alloys

Particulate Dusts. ..•........ „ ....... „ .... „-„ •.•..................•................... 256 5.4.6.4 Recycling and Reuse of Alloy Fines„ ......................................... 257 5.4.6.5 Characteristics of Manganese Ferroalloy Slags ........................ 257 5.4.6.6 Recycling and Reuse of Ferromanganese Alloy Slags ............ 259 5.4.6.7 Recovery of Manganese from Ferromanganese Alloy Slags ...... 259 5.4.6.8 Hydrometallurgical Processing of Ferromanganese Slags„.„260

x Contents

5.5 Silicon and Its Alloys ......... „„ .. „ ...... „„ ................... „.„„ .. „ .................. „ ..... „„.„ .. „„. 263 5.5.1 5.5.2 5.5.3

Chemical and Physical Properties of Silicon ..... „.„„ ....... „ ............. „„ .... „ 263 Occurrence of Silicon........... . ,,,.„..," ... „ ...... _ _.,„„„.„ .. „„.„.„„.„„„„„„„ .. „. 263 Industrial and Commercial Applications of Silicon.„.„ ... „„ ........ „ ......... 264 5.5.3.l Metallurgical Applications of Silicon .......... „„.„.„.„ ....... „ .. „„ .. 264 5.5.3.2 Chemical Refining Process of Metallurgical-Grade

Silicon .... „. „ ... „ .• „ .. „ ... „ .•. „ .. „ „ „ ..• „ ....• „ „. „ .. .. _. „ „ •• „ .. „ ... „ ... „ .... „ 266 5.5.3.3 Metallurgical Refining Process of Metallurgical-Grade

Bllicon-.... „ .....•• „„ ...... „ .... „„,_ ........ - ........... .Y-.-„ •. „ •......... „ .. „ .. 267 5.5.3.4 Silicon Applications in Chemicals and Polymers „„„„„ ...... „„ 268

5.5.4 Production of Silicon and Its Alloys ... „ ...... _ .. _ ..... „ „._ .. „.„ ..•.... „ ... 269 5.5.4.1 General Considerations in the Production of Silicon and

Ferrosilicon Alloys ....... „ .„„. „ „ •• „ ...... „„ .. „„„.„„.„„„„„ .... „„ .... „ 269 5.5.4.2 Characteristics of Silicon-Bearing Raw Materials ..... „ ..... „„„„ 271 5.5.4.3 Characteristics of Carbon Reductant Materials ........ „„„„ .... „.272 5.5.4.4 Composition of Industrial-Grade Silicon .... „ ..... „ .. „.„„ ............ 273 5.5.4.5 Composition of Ferrosilicon Alloys„„ ... „ .. „„ .. „„ ... „„.„ .. „„ ...... 274

5.5.S Physicochemical Characteristics of Silicon and Ferrosilicon Slags„„ ... 274 5.5.6 Physicochemical Characteristics of Silica Fume Dust „„„„„„„„„„ .. „„„ 275

5.5.6.l Utilization ofSilica Fume Waste Dusts .. „„.„ .... „.„ .. „ ... „ .. „„ .. „276 5.5.6.2 Utilization of Silica Fume in Ceramic and Composite

Materials „„ .... „ ........ „ ..... „„„„„ .. „ .. „ ... „ .. „.„„„„ ... „ .. „ ......... „„ ..... 277 5.5.6.3 Utilization of Silica Fume in Cementitious Systems ... „ .. „.„ ... 277 5.5.6.4 Summary .... „ ................................ „ ................ „ .......... „ .. „ .... „.„ .. „ 278

5.6 Concluding Remarks ........................................................................... „ ........... „ ...... 279 References ... „„.„ ......... „ ..... „ ....... „ ........ „„ ............. „.„ .... „„ .... „„ ............... „ ..... „ ..•....... „ ...... 280

6. Base Metals Waste Production and Utilizapon„„ .. „„„„„ ... „„„„„„„„„„„„ .... „„ .......... 299 6.1 Introduction ............................. „ .. „ •. ... „ ... „ .. „„.„ ........ „ ..... „ ........................... „ .... „.„ 299 6.2 Pyrometallurgical Extraction of Copper .„ .. „ ...... „ .... „ ...... „.„ ....... „.„„.„ .. „ ....... „ .. 299

6.2.1 Chemical and Physical Properties„„ ......... „ ...... „ ........ „„„„„ ...... „.„ ......... 299 6.2.2 lndustrial Uses of Copper and Copper Alloys „ .......... „ .. „ .. „„„ .............. 300 6.2.3 Occurrence of Copper .„ ... „ .... „ .... „ ................................ „ ........................... 300 6.2.4 Mining and Beneficiation of Copper-Bearing Ores.„ •.. f. •••••••••• „ .... „ ..... „ 302 6.2.S Concentration of Copper-Bearing Minerals by Flotation Process „ .. „ .. 303 6.2.6 Production of Copper from Copper-Iron Sulphide Concentrates .... „„303

6.2.6.1 Fundamentals Considerations ...... „ ..... „.„ .•. „ •..•.• „ ................... „303 6.2.6.2 Smelting of Copper Sulphide Concentrates .... „ ..... „ ........ „ ... „. 303 6.2.6.3 Converting of Copper Mattes ..... „ .• „„.„ ... „„.„„ ......................... 304 6.2.6.4 Fire Refining of Blister Copper „„.„ .. „„„„„ .... „.„ ..... „.„ ............. 305 6.2.6.S Electrorefining of Copper Anodes .„ ............ „„ .. „.„„„„„„ .. „ .. „. 305

6.3 Pyrometallurgical Processing of Nickel, Cobalt and Platinum Group Metals ....... „ .......•.................. „ ........ „ .•.......... „ ....•. „ ........•.•................... . ... . ..... 306 6.3.1 Chemical and Physical Properties of Nickel, Cobalt and Platinum

Group Metals ....... „„ ..... „ .... „„„ ... „ .. „ ..... „ ... „ ..................... „ .... „ ....... „ ..... „ .. 306 6.3.1.1 Chemical and Physical Properties of Nickel .. „ ...... „„ ... „ .. „ .. „.306 6.3.1.2 Chemical and Physical Properties of Cobalt „„.„.„.„„.„„„„ .. „ 306 6.3.1.3 Chemical and Physical Properties of Platinum Group Metals .. „306

Contents xi

6.3.2 Industrial and Commercial Uses of Nickel, Cobalt and Platinum Group Metals .................................................................................... „„„ ...... 307 6.3.2.1 Nickel and Cobalt.„„.„ ....... „ ......................... „ ........ „ ........ „ ......... 307 6.3.2.2 Industrial and Commercial Uses of Platinum Group Metals.„ .. 307

6.3.3 Occurrence of Nickel, Cobalt and Platinum Group Metals ... „ ....... „ ..... 310 6.3.3.1 Occurrence of Nickel. ................................... „ .............................. 310 6.3.3.2 Occurrence of Cobalt .. „ ........................ „.„ ........... „„ ................ „.310 6.3.3.3 Occurrence of Platinum Group Metals .... „ ... „.„„„„„ ... „ .......... 310

6.3.4 Primary Production Processes of Nickel, Cobalt and Platinum Group Metals.„ ...... „ .... „ .. „„ .... „ ................................................. „„ ... „.„„„ .. 311 6.3.4.1 Fundamentals of Nickel Production .... „ ... „ ....... „ .. „„„ ..... „ ..... „ 311 6.3.4.2 Fundamentals of Cobalt Production „„ .... „„.„„„„„.„„ .... „.„ .... 312 6.3.4.3 Fundamentals of Platinum Group Metals Production .„.„ .. „.313 6.3.4.4 Beneficiation of Base Metal and Platinum Group Metal

Sulphide Minerals '- .... „„ .... „ ..... „„.„ ........................................... 314 6.3.4.5 Smelting and Converting of Nickel, Cobalt and Platinum

Group Meta! Concentrates .......................................................... 315 6.3.4.6 Converting of Sulphide Mattes .................................................. 315 6.3.4.7 Refining of High-Grade Nickel and Cobalt Matte .................. 316 6.3.4.8 Sulphide Smelting Peculiar to Platinum Group Metal

Concentrates ....................................•......... „ .................................. 317 6.3.4.9 Converting and Refining of PGM Mattes ................................. 317

6.4 Waste Production and Utilization in the Base Metal Production Processes ..... 318 6.4.1 General Considerations .......................................... „ ............ „ ..................... 318 6.4.2 Smelter and Converter Particulate Dusts ............................ „ ....... „„ ........ 319 6.4.3 Recycling and Treatment of Base Metal Smelter Particulate Dusts ...... 321 6.4.4 Gaseous Emissions ...................................................................................... 323 6.4.5 Physicochemical Characterization of Base Meta! Slags .......................... 323 6.4.6 Recycling, Metal Recovery and Utilization of Base Meta! Slags ....... „ .. 325

6.5 Concluding Remarks ............................... „ ...... „ ....................................................... 325 References ...................................................... „ ..................................................................... 326

7. Hydrometallurgical Waste Production and Utilization ............ „ ................ „ ............... 331 7.1 Introduction ....................... „ .......... „ ........ „ ................................................................ 331 7.2 Leaching ............. „„ ........................................................... „ .... „ ...... „„„„„„ ...... „ .. „„.332

7.2.1 Acidic and Alkaline Leaching .... „„ ........... „ ... „„„.„.„ ... „ .. „.„ ... „„ .... „ ... „ .. 332 7.2.2 Leaching with Metal Salts„ .....••. „ ...•.•...•... „ ..............•.....•.•............•............ 333 7.2.3 Bioleaching ..•.. „ .....................•.•...•...•.•...•. „ ..... „ •••. „ ..•................. „ ...•....... „ ..•. 333

7.3 Purification and Concentration Processes ................ „ .... „„„„.„.„ ......................... 334 7.3.1 Chemical Precipitation Processes ...... „ ...... „ .............................................. 335 7.3.2 Solvent Extraction ....... „ .... „„ .......................................... „ ..................... „ .... 337 7.3.3 Ion Exchange ........... „ .. „.„ ....... „„ ... „.„„ ...................... „„ ................ „ ........... 339 7.3.4 Adsorption Processes „„ ....... „„ ...... „ .... „ ............. „ ... „„„.„ ... „ ....... „.„ ......... 340 7.3.5 Biosorption Processes„.„.„ ..... „ .... „ ....... „ ...... „ ..... „ ... „.„.„ ....... „„„„ ... „ ... „.341

7.4 Electrochemical Processes.„ ................................................ „ ..••.....•..•.•.....••..•...•...•.. 342 7.4.l Cementation P.rocesses ............. „„ ............................................................... 342 7.4.2 Electrowinning ............................................................................................. 343 7.4.3 Electrorefining .............................................................................................. 343

xii Contents

7.5 Base Metals Production.„_,_ •. „.„ . .;." _ ... „ .......... - .....•.. „ .... „ .. „ : .. „ •.......••. „ .............. 344 7.5.1 Production of Copper .._ _ ___ .... „„ •....•..... -„; ••• -. •..••• _ .•..•..•...•..•.....••..••.•. 344

7.5.1.1 Crud Formation, Treatment and Recycle .................................. 346 7.5.1.2 Treatment of Anode Slimes from Copper Electrolytic Refining .... 347

7.5.2 Nickel and Cobalt Production •......... „.„ ......................•..•..............•............ 350 7.5.3 Production of Zinc ··-·-·---.... ·-4„ •••• „ ....... „ .... „ ............ „ .... „ ......................... 351

7.5.3.1 Jarosite Production and Utilization ....... „„ ................................ 352 7.5.3.2 Potential Utilization of Jarosite ............................................. „ ... 353 7.5.3.3 Goethite Production and Utilization ... „ ......... „.„ .. „ ...... „.„ ... „„356 7.5.3.4 Potential Utilization of Goethite „„ ... „ .. „ .•... „ ............................ 356 7.5.3.5 Hematite Production and Utilization .. „ ............ „ ........ „„ .......... 357 7.5.3.6 Summary .. „ .... „.„ ......... „ ....... „„ ........ „ ....... „.„.„.„.„.„„ ........ „ .. ... „ 358

7.5.4 The Bayer Process for Alumina Production ........................... „ ....... „ ....... 358 7.5.4.1 Characterization of the Red Mttd„.; ................................ „ .......... 360 7.5.4.2 Utilization of Red Mud •.. „„„ ......... , ..•................ „ .••••••.•...••••••..•.••. 360 7.5.4.3 Metallurgical Utilization through Metal Recovery ................. 361 7.5.4.4 Recovery of Iron ............. „ ............ „„„ ............................................... 363 7.5.4.5 Recovery of Aluminium and Titanium ..................................... 364 7.5.4.6 Recovery of Rare Earth Elements ............................................... 365 7.5.4.7 Utilization of Red Mud in Building and Construction

Materials .................. „ ....... „ ..... i„„ •••• ••••••••••••• ••••••••••••••••••••••••.•• „ ... 367 7.5.4.8 Glass-Ceramics and Pigments ......•.................. „ ......................... 369 7.5.4.9 Other Applications •..... „„ ................... - . .. „ ......•.. „ ....•. „ ............... 369 7.5.4.10 Summary ......... „ ................. „„ ........................... ~··'·······-··-··········· 370

7.6 Precious Metals Production.„ .... „„ .. „ .............. „ ... „„ ............................ „ ................. 371 7.6.1 Production of Gold „ . .. ... „.„ .. „„ ...... „ ... „ .... .. „ .... „„„„„„.„.„ ... „ ...... „„ ...... „. 371

7.6.1.1 Recovery and Recycling of Cyanide from Gold Tailings .. „ .... 372 7.6.2 Production of Platinum Group Metals „ ..... „ ... „.„„ •..... „ .... „ ....... „ .....•..... 374

7.6.2.1 Recovery of PGMs from Refining Waste„ ................. „ ....... „ .. „.375 7.7 Strategie and Critical Metals ......... „ ....................... „ ................... „ ........ 1 •••••••••••••••••• 377

7.7.1 Production of Uranium ... „ ..•.... - ..•..... „ ..•. „„ ......••.•..•..........•... „ ... „„ .•..... - .. 377 7.7.2 Production of Rare Earth Elements ........................................................... 381

7.8 Final Remarks ....... „ .... „„.„„ .... „.„„ .. „ .... „.„.„.„ ... „ .•....•.. .• .. „ .. „„.„.„„.„ .. „„„ ...... „„„382 References ... ...... „ .... .•...... .. „ •..... .. .... ........... . . „„ .... ................ „ .. .. .. .. .... .... „ .. ........ „ ......... .. „ .... 382

8. Metal Manufacturing and Finishing Waste Production and Utilization ................. 395 8.1 Introduction ····-··-·······----·--·--·-"··· .... ······•·'„„ .. „ .. „ •. ,,1 ............. „ ..........•............ 395 8.2 Metal Forming Processes ······---··········--····-··-·-··..,,,,·····---·--····························396

8.2.1 General Considerations of the Rolling Process ....................................... 397 8.2.2 Cold Rolling Process ... „„.„ ....•....• „ ...... „-.„„ ............ „ ................................ 397 8.2.3 Hot Rolling Process „ ...........•. „ .... „ ..... r.„.l.l..-.„ • .i.„ •••••••• ••••• ; •••••••••••• „ ........... 398 8.2.4 Formation of Adherent Oxide Scale during the

Reheating Process ... „ .••......• „ .•••.••••• - ...... - •••• „ ..• c„ •• „ ..... „ ............................. 399 8.2.5 Adherent Oxide Scale Formation during the Heat Treatment

of Formed Products .. „ ........... ..... „ ......... „ ... „ ....•.•.. - .•.. „ .......• „., ... „ ........ „ .... 399 8.2.6 Characteristics of Adherent Oxide Layers .................. „ ..... .....•...•........... .400 8.2.7 Recycling and Utilization of Surface Oxide Scale Material .. „ ............... 401

8.3 Pickling of Formed and Heat-Treated Steel Product:s ..... „ .... „ .............•... „ .......... 402 8.3.1 Overview of the Pickling Process .............................................................. 402

Contents xiii

8.3.2 Preliminary Pickling Processes ............. „ ................................................... 403 8.3.3 Final Pickling Processes ...............• „ ........................ „ ........... „ ... „ ....... „ ....... 404 8.3.4 Waste Generation in Pickling Process .................................... „ .. „„.„.„ .... .404

8.4 Metal Finishing Processes ...................................•.............. „ .. - .. „.„ ........... „ ............ 407 8.4.1 Electroplating and Surface Treatment Processes ................................. „ . .407 8.4.2 Galvanizing Process .................................. „ ............ „ .................................. 408 8.4.3 Waste Generation from Electroplating and Galvanizing Coating

Processes.·--······-·--··---····-·····•···""·•···-·-·-··-·„·--„.„ ............ „ ..... „ ... „ 408 8.4.4 Treatment of Electroplating and Galvanizing Waste Streams .„.„ ........ .409 8.4.5 Waste Recycling and Utilization from Pickling and Metal

Finishing Processes „„ .. „„ ........... -„ ..... „ ...•.. „ .... „ ....... „ ..... „ ........................ 409 8.4.5.1 Metal Recovery from Pickling and Plating Sludges ............ „ .. 409 8.4.5.2 Treatment and Regeneration of Spent Pickling Solutions .„ .. .410

8.5 Foundry Processes .. „.„ .. ~ .. „ ... „.„ .....•• „„„„„ ........ „„.„„ ........... „ ...... „ .......... „ ..... „ ... 410 8.5.1 Introduction .... „„ ...... --···-·--···········„„ ... „.-„.„.„ .. „ ... „ .. „.„ ............ „„ ... 410 8.5.2 Process Description of Foundry Processes .. „.„ •.•.... „ ............ „ .. „„ ........... 412 8.5.3 Generation of Waste Streams in the Foundry Melting Process ............ .413

8.5.3.1 General Fundamentals „.„„ •.. „ .................................. „ ................ 413 8.5.3.2 Waste Generation in the Melting Process ........ „ .... „ .... „ ....... „ . .413

8.5.4 Generation of Waste Streams in the Moulding Process.„.„„ ...... „ ... „ .... .416 8.5.4.1 Fundamental Considerations ........ „ ....... „ ......... „„„.„ ............ „ .. 416 8.5.4.2 Sand Moulding Processes .... „ .... „ ................ „ ........ „.„ ................ 418 8.5.4.3 Waste Generation in the Moulding Process ..... „ .... „„.„.„„ ..... .421

8.5.5 Recycling and Utilization of Foundry Process Wastes ... „„ .. „ ....... „.„.„. 421 8.6 Concluding Remarks.„.-... „.„ ...... „ .. „ ..••. „„ .. „ ..•. „„.„ .....• „ .•••.• „„ ............................ 421 References „.„.„ ........... _ ........... „ ....................... „.„ •...•. ~ •...• „ ...... „ .............. „ ........................ 422

9. Post-Consumer Waste Production and Utilization ...................... „.„ ............................ 427 9.1 Introduction ............................................................... „ ........ „„ •••••....•.....••. • „ ............. 427 9.2 Legislation and Policies Governing Post-Consumer Wastes „ .......... „ ...... „ .. „.„.427 9.3 Recyclable Metals---·----··-·-··-·····---··„„ ............ „ .. „ ••. „ ...• „ ......... „„ .. „„ .... „"".428

9.3.1 .AJUJllinjum ······--·„-·.„ •. „„ ..... „ ..... „ .• „„ .. „„„„„.„„.„ ........ „.„ ......... „.430 9.3.1.1 Chemical and Physical Properties of Aluminium ....... „ .. „„ ... .430 9.3.1.2 c.ou:rrence •. „ ..... „.,,.,,,,,.„.„ ••• , .... „,.m•••n••••"''"-'•"•••••„•••••••••"••••••431 9.3.1.3 Uses of Aluminium„ ........ „„._. ••. „.„„ ... „ .. „„„ ...•.... „ ..... „.„.„ ...... 433 9.3.1.4 Post-Consumer Recycling Processes .... „.„ .. „„.„„„ .... „ ....... „ .... 433

9.3.2 Copper „ ................... „ ...•.• „ .•....... „ .. ._„ ........ „ •.• „ .... „„.„.„ ..... „ ... „ ................ 435 9.3.2.1 Chemical and Physical Properties of Copper .......................... .435 9.3.2.2 C>ccurrence ...................•....... „.„.„.„ ......... „ ..... „ ............................. 436 9.3.2.3 Uses of Copper .................................... „ ........................................ 436 9.3.2.4 Post-Consumer Recycling Processes ......................................... 437

9.3.3 Lead ............................... „ ........ .. „ ........... „„ •. „ .......... „ ........ ........ .. „„ ............ .. 438 9.3.3.1 Chemical and Physical Properties of Lead ............................... 438 9.3.3.2 ()ccurrence ... _.„ ..... - .. „ •.• „ .•..• „ ••.. „-.„-..... „„.„ ............................ 439 9.3.3.3 Uses of Lead .. „ ................. „ ................... „ ....... „ ........ „ ................. „439 9.3.3.4 Post-Consumer Recycling Processes ....... „ ..•.•....•....••.•.......••.•... 440

9.3.4 Zinc .... „ ......... „ ... „ .••......................•.•.................• „ .......................................... 444 9.3.4.1 Chemical and Physical Properties of Zinc ................................ 444 9.3.4.2 C>ccurrence ............................................ „.„ .............. „ .................... 444

xiv Contents

9.3.4.3 Uses of Zinc ................................................................................... 445 9.3.4.4 Post-Consumer Recycling Processes ......................................... 445

9.3.5 Tm .. ·-··---···-·······-··· .... -~ ..... ,,._,._„ ..... „.1 ......... „_ .••. „ ..... „ ............•.................. 447 9.3.5.1 Chemical and Physical Properties of Tm .„ •••.•. „ ... „.„ ... „ .. „„ ••.. 447 9.3.5.2 C>ccurrence ....••. „ ..........•.......... - ...........•..... „ ................................. 448 9.3.5.3 Uses of Tm ........ „ ........ _ .......... „ ..................................................... 448 9.3.5.4 Post-Consumer Recycling Processes ......... „ .............................. 449 9 .3.5.5 Pretreatinent ......•........ - ................................................................. 450 9.3.5.6 Extraction •..............•....•........... „ ... „ •......••..•...••..••........•.•...... .......... 451

9.3.6 Steel ................ „ .... „ ... - ...............•......•................•........................................... 452 9.3.6.1 Introduction ................................................................. „ ............... 452 9.3.6.2 Types of Steel .„ ............................. „ ••••••.• „ ......... „ ......................... 453 9.3.6.3 Uses of Steel .................................................................................. 453 9.3.6.4 Post-Consumer Recycling Processes ..... „ ................................. .454

9.4 Critical Post-Consumer Sectors .... -.„ ..... „.__ •••••••• „ .•.• _ ...• 1 •• „ ........... „ .................... 458 9.4.1 Electronic Waste ........... „ ......••....•...... „ .................. „ ....... „ . ••. •••.•....•.•••. „ ..... „460

9.4.1.1 Introduction ........ „ ............ .......... „ •.. „ ........................................... 460 9.4.1.2 Post-Consumer Recycling Processes ........... „ ...... „.„ ................ .460

9.4.2 Spent Catalysts ........................ „ ......... „ ........................................................ 466 9.4.2.1 Introduction .... „,c;„,, • .; •• „ ......... „-. ..;.„ ••• „ .......... ; „ •.••.•.•••••.•.•..••.••••• 466 9.4.2.2 Post-Consumer Recycling Processes „ ....•..... „ , „ •••..••...•••.......• 1 •• 466

9.4.3 Automobile ............................................... „ ............................................ .. .... 470 9.4.3.1 Introduction „ .. „ ............................................................................ 470 9.4.3.2 Post-Consumer Recycling Processes ...................... „ ................ .470

9.4.4 Household Equipment ................................. „ ............ „ ... „.„ ....................... 473 9.4.4.1 Post-Consumer Recycling Processes ......................................... 473

9.5 Concluding Remarks ................................................... „ ......••••....... ...........•. „ ........... 474 References .....................•.. „ ••........•..•••••.••...•.••••.••. „ .......... „.„ .......... „.„ ..•........ „ ..•..••.•.........•. 475

10. Conclusions and Future Outlook .. „„ ...................................................... „ . ............. „ •.... . 487 10.1 Introduction .. „ ..... „ .................................................................................................... 487 10.2 Challenges .............................................. „ .........•..•....•............••...•.............................. 489

10.2.1 Lack of Adequate Regulatory Frameworks and Policies ................... „ . .489 10.2.2 Complexity of the Residue Material versus Available Technology ............ 490 10.2.3 Economic Viability ................................................................................... „ .. 491 10.2.4 Market Availability and Acceptance of the Secondary Products .......... 492

10.3 Future Outlook ........ „„ ....• - .. „.„ .....•••.. .••••...•••.••........••. ..... .•.... .•... ...........•••••.••...... .•.. 493 10.3.1 Waste Managerr.ent and Utilization Opticms .................. „ •.•.•... „ .. „ ..... „ . .494

10.3.1.1 Zero Waste Process Approach ............................... „ ..•...•.••...•..•. .494 10.3.1.2 Synergy between the Residue Producers and Residue

End Users: lndustrial Symbiosis .... „„ .... „ .. „ .. „„ ........ „ . . . ... „ ..... .495 10.3.2 Process Integration and Intensification .„ .............. „ ..................... „„.„ .... .496

10.3.2.1 An Integrated Approach to Mineral Waste Utilization .......... .496 10.3.2.2 Process Intensification ................................................................. 497

10.4 Concluding Remarks ............................................................................ „ ......... ......... 498 References ....... „.„ .••• - ...•. .•...•.. •.....•..•.•.•......•... •.....••................•........... •• .......•.•.•.•.............•.... 499

Index .... „ .. „ ... „„ ................... „„„ ...... „ ............................. „ .. „.„ ..................................................... 501