RECOVERY OF VALUABLE MATERIALS FROM FINE INDUSTRIAL WASTE STREAMS by Myungwon Jung A thesis submitted to the Faculty and the Board of Trustees of the Colorado School of Mines in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Metallurgical and Materials Engineering). Golden, Colorado Date: Signed: Myungwon Jung Signed: Dr. Brajendra Mishra Thesis Advisor Golden, Colorado Date: Signed: Dr. Ivar Reimanis Interim Department Head Department of Metallurgical & Materials Engineering ii ABSTRACT The recycling of metals from waste streams is important since natural resources could be conserved by recovering metals from secondary sources. Moreover, environmental problems due to the waste disposal also could be alleviated by removing volatile and toxic materials from the wastes. In general, high-temperature materials processing generated off-gases contain a large amount of dust. Therefore, dust collection systems, such as baghouse and cyclones, are usually installed in these facilities to control the emission of air pollutants. Dust collected from various facilities usually contains some metal values; however, most fine wastes are landfilled currently. In this study, recovery of valuable metals from fine wastes is investigated by hydrometallurgical and pyrometallurgical processes from bottom ash from the municipal solid waste incinerator (MSWI), fly ashes from coal/oil fired power station, light fluff from end-of-life vehicle shredder, and baghouse dust from the secondary aluminum smelter and steel foundry. The elemental and mineralogical compositions of wastes are different depending on the industry where they come from. Therefore, these waste streams are initially analyzed by the inductively coupled plasma atomic emission spectroscopy (ICP-AES). Several wastes, which contain a relatively large amount of aluminum, silicon, calcium, and iron, could be used as a source of construction material since these elements are the major components of concrete. On the other hand, oil fly ash and aluminum smelter baghouse dust show a high concentration of vanadium and aluminum, respectively. For these reasons, this study mainly focuses on the recovery of vanadium and aluminum from these waste streams by hydrometallurgical and pyrometallurgical processes. In this research, aluminum smelter baghouse dust is treated by alkaline leaching followed by Al(OH)3 precipitation to extract aluminum selectively, and vanadium extraction from oil fly ash is investigated by salt-roasting followed by hot water leaching. Thermodynamic and kinetic modeling of the results also has been studied for a deeper understanding of experimental phenomena. iii TABLE OF CONTENTS ABSTRACT ................................................................................................................................... iii LIST OF FIGURES ...................................................................................................................... vii LIST OF TABLES ......................................................................................................................... xi ACKNOWLEDGMENTS ............................................................................................................ xii CHAPTER 1 INTRODUCTION ...................................................................................................1 1.1. Benefits of Materials Recycling ...........................................................................................1 1.2. Literature Review of Mineral Processing ............................................................................1 1.2.1. Comminution .............................................................................................................2 1.2.2. Basic Methods of Mechanical Size Reduction ..........................................................4 1.2.3. Crushers .....................................................................................................................5 1.2.4. Grinding Mills ..........................................................................................................10 1.2.5. Separations ...............................................................................................................11 1.2.6. Gravity Concentration ..............................................................................................12 1.2.7. Flotation ...................................................................................................................16 1.2.8. Sortation ...................................................................................................................17 1.2.9. Magnetic Separation ................................................................................................18 1.2.10. Electrostatic Separation .........................................................................................19 1.3. Literature Review of Extractive Metallurgy .....................................................................20 1.3.1. Pyrometallurgy .........................................................................................................22 1.3.2. Hydrometallurgy ......................................................................................................26 1.3.3. Electrometallurgy .....................................................................................................32 1.4. Fine Wastes from Various Sources ....................................................................................37 1.4.1. Bottom Ash from Municipal Solid Waste Incinerator ............................................37 1.4.2. Shredded Light Fluff from End-of-Life Vehicle .....................................................38 1.4.3. Baghouse Dust from Steel Foundry and Secondary Aluminum Smelter ................39 1.4.4. Fly Ash from Power Plants ......................................................................................40 CHAPTER 2 GENERAL EXPERIMENTAL PROCEDURES ..................................................42 2.1. Waste Characterization .....................................................................................................42 2.1.1. Inductively Coupled Plasma Atomic Emission Spectroscopy ...............................42 iv 2.1.2. Oxygen Bomb Calorimetry ....................................................................................42 2.1.3. Loss on Ignition .....................................................................................................45 2.1.4. X-ray Diffraction ...................................................................................................46 2.2. Metal Recovery Procedures ...............................................................................................47 2.2.1. Size Classification ..................................................................................................47 2.2.2. Leaching .................................................................................................................47 2.2.3. Crystallization ........................................................................................................48 2.2.4. Carbon Burning ......................................................................................................49 2.2.5. Salt Roasting ..........................................................................................................50 2.2.6. Electrowinning .......................................................................................................51 CHAPTER 3 RESULTS AND DISCUSSION ............................................................................53 3.1. ICP Analysis of As-received Samples ...............................................................................53 3.2. Heat Values of As-received Samples .................................................................................53 3.3. Aluminum Smelter Baghouse Dust ..................................................................................56 3.3.1. Loss on Ignition of Aluminum Smelter Baghouse Dust ........................................57 3.3.2. XRD Analysis of Aluminum Smelter Baghouse Dust ...........................................57 3.3.3. Effect of Reagent and Temperature on Al SBD Leaching ....................................58 3.3.4. Effect of Solids Content on Al SBD Leaching ......................................................60 3.3.5. Effect of Particle Size on Al SBD Leaching ..........................................................61 3.3.6. Kinetic Study of Al SBD Leaching .......................................................................64 3.3.7. Thermodynamic Study of Al SBD Leaching .........................................................69 3.3.8. Leach Solution Preparation for Al(OH)3 Precipitation ..........................................71 3.3.9. Thermodynamic Study of Al(OH)3 Precipitation ..................................................74 3.3.10. Al(OH)3 Precipitation by pH Adjustment ..............................................................77 3.3.11. Proposed Flowsheet of Aluminum Recovery ........................................................80 3.4. Oil Fly Ash .........................................................................................................................81 3.4.1. Loss on Ignition of Oil Fly Ash .............................................................................82 3.4.2. TGA-DTA Analysis ...............................................................................................82