Surface Chemistry of Froth Flotation

I. Introduction.- 1.1. Scope of Froth Flotation.- 1.2. An Outline of a Mineral Flotation System, Definitions.- 1.3. Typical Flotation Procedures and Flowsheets.- 1.4. Mineral Liberation Size.- 1.5. Some Problems Encountered in Separations of Minerals.- 1.6. Examples of Industrial Separations of Sulfide Minerals.- 1.6.1. Lead-Zinc Ores.- 1.6.2. Copper Ores.- 1.7. Examples of Industrial Separations of Oxidized Ores of Copper, Lead, Zinc, Iron, and "Nonmetallic" Minerals.- 1.7.1. Separations of the Superficially Oxidized and Oxide-Type Minerals.- 1.7.2. Separations of the "Nonmetallic" Industrial Minerals..- 1.8. Separation of "Soluble Salts" from Saturated Brines.- 1.9. Flotation of Silicate Minerals.- 1.10. Separation of Naturally Hydrophobic Minerals.- 1.11. Recent Developments in Industrial Flotation Operations and Research Techniques.- 1.12. Flotation Literature.- 1.13. Selected Readings.- 1.13.1. Flotation Theory.- 1.13.2. Flotation Practice.- 1.13.3. International Conferences.- 1.13.4. List of Periodicals Regularly Publishing Papers on Flotation Theory and Practice.- 1.13.5. List of Periodicals Publishing Occasional Papers on Flotation Chemistry.- 2. Chemical and Molecular Bonding. Interfacial Energetics.- 2.1. Ionic Bonding.- 2.2. Covalent Bonding.- 2.3. Partial Ionic-Covalent Bonds.- 2.4. Dipole Moments and Dipole-Dipole Interactions.- 2.5. Hydrogen Bonding.- 2.6. London Dispersion Forces, van der Waals Interactions.- 2.6.1. Dispersion Forces Between Macroscopic-in-Size Aggregates of Atoms.- 2.6.2. Practical Significance of van der Waals Interaction.- 2.7. Metallic Bonding. Band Theory of Solids.- 2.8. The Importance of Steric (Size) Parameters in Interfacial Bonding.- 2.9. Interfacial Thermodynamics, Definitions and Concepts.- 2.9.1. ThermodynamicRelationships in Chemical and Electrochemical Systems.- 2.9.2. Thermodynamics of Adsorption at an Air/Liquid Interface.- 2.9.3. Thermodynamics of Adsorption at a Solid/Liquid Interface.- 2.9.4. Thermodynamics of Thin Liquid Layers.- 2.10. Interfacial Wetting and Contact Angle Relationships.- 2.10.1. Interpretations of Contact Angle.- 2.10.2. Dynamic Aspects of Wetting and De-wetting.- 2.10.3. Critical Surface Tension of Low-Energy Solids.- 2.11. Liquid/Gas and Liquid/Liquid Interfaces.- 2.12. Selected Readings.- 2.12.1. Chemical and Molecular Bonding.- 2.12.2. Thermodynamics.- 2.12.3. Interfacial Relationships.- 3. Structure of Solids.- 3.1. Atomic Packing.- 3.2. Crystal Structures of Simple Compounds.- 3.3. Structural Changes and Chemical Relationships.- 3.4. Structures Containing Finite Complex Ions.- 3.5. Silicates.- 3.6. Selected Readings.- 4. Water and Aqueous Solutions.- 4.1. Structural Models.- 4.2. Hydration of Ions.- 4.3. Debye-Hückel Model of Ions in Solution.- 4.4. Ion-Pair Formation.- 4.5. Dissociation of Water and Acids.- 4.6. Solubility of Gases in Water.- 4.7. Solubility of Hydrocarbons in Water.- 4.8. Dissolved Mineral Constituents.- 4.9. Antipollution Treatment of Mill and Mine Effluents.- 4.10. Selected Readings.- 5. Flotation Surfactants.- 5.1. Classification of Surfactants.- 5.1.1. Hydrocarbon Groups (R) Nomenclature.- 5.1.2. Less Common Flotation Surfactants, Mono- and Multipolar.- 5.1.3. Commercial Flotation Reagents.- Class I: Thio Compounds.- 5.2. Xanthates.- 5.2.1. Preparations of Alkali Xanthates.- 5.2.2. Aqueous Solutions of Xanthates.- 5.2.3. Insoluble Metal Xanthates.- 5.3. Dithiocarbamates.- 5.4. Mercaptans (Thiols).- 5.5. Dithiophosphates.- Class II: Non-Thio lonizable Surfactants.- 5.6. Dissociation and Hydrolysis.- 5.7. Surface TensionVersus Concentration Relationship.- 5.7.1. Aqueous Solutions of Non-Thio lonizable Surfactants..- 5.7.2. Surface Tension-Concentration Relationships for Surfactants Which Do Not Form Micelles.- 5.7.3. Ideal and Nonideal Mixtures of Soluble Surfactants, Synergistic Effects.- 5.7.4. Dynamic Surface Tension.- 5.8. Krafft Point and Cloud Point.- 5.9. Micelle Structures.- 5.10. Carboxylates.- 5.10.1. Carboxylic Acids.- 5.10.2. Metal Carboxylates (Soaps).- 5.11. Alkyl Sulfates and Sulfonates.- 5.12. Alkyl Amines and Substituted Amines.- Class III: Nonionic Surfactants.- 5.13. Alcohols.- 5.14. Ethers.- 5.14.1. Polyoxyethylene Nonionic Derivatives.- 5.14.2. Polyoxypropylenes and Block-Polymer Nonionic Surfactants.- 5.15. Organic Regulating Agents.- 5.15.1. Cellulose, Starch, and Their Hydrolysis Products.- 5.15.2. Derivatives of Starch and Cellulose.- 5.15.3. Wood Extracts: Quebracho and Wattle Bark, Lignin and Tannin Derivatives.- 5.16. Commercial Flocculating Agents.- 5.17. Selected Readings.- 6. Physical Chemistry of Surfaces and Interfaces.- 6.1. Types of Interfaces. Colloids.- 6.2. Characteristics of a Solid Surface.- 6.3. Adsorption and Its Characteristics.- 6.4. Thermodynamic Models of Isotherms for Physical Adsorption.- 6.4.1. The Henry's Law Isotherm.- 6.4.2. The Langmuir Adsorption Isotherm.- 6.4.3. Adsorption Isotherms for Mobile Adsorbates.- 6.4.4. Polanyi's Potential Theory Isotherms.- 6.4.5. BET Theory [Brunauer, Emmett, Teller (1938)] of Multilayer Adsorption.- 6.4.6. Frenkel-Halsey-Hill Slab Theory of Adsorption.- 6.5. Mechanical Effects of Adsorption at Solid/Gas Interfaces.- 6.6. Models of Isotherms for Chemisorption.- 6.7. Characterization of Adsorption from Solutions (in Particular at Solid/Liquid Interfaces).- 6.8. Oxidation of Surfaces of Metals andMetallic Sulfides.- 6.9. Hydration of Surfaces. Thin Films.- 6.10. Insoluble Monolayers of Surfactants at the Air/Water Interface. Interactions Among Surfactants.- 6.10.1. Monolayer Penetration, Molecular Association of Surfactants at the Air/Liquid Interface.- 6.10.2. Solidification of Ionized Monolayers on Reaction with Counterions.- 6.10.3. Interactions Between Surfactants at the Solid/Liquid Interface.- 6.11. Selected Readings.- 7. Electrical Characteristics of Interfaces. Electrical Double Layer and Zeta Potential.- 7.1. Definitions and Electrochemical Concepts.- 7.2. Models of the Electrical Double Layer.- 7.3. Experimental Testing of the Double-Layer Theory (Using an Ideally Polarizable Electrode).- 7.4. Adsorption of Neutral (Nonionic) Surfactants at the Mercury/Electrolyte Interface.- 7.5. Charge Transfer Across the Electrical Double Layer.- 7.6. Semiconductor/Solution Interfaces.- 7.7. Electrical Double-Layer Studies Relevant to Flotation.- 7.8. Electrokinetic Effects.- 7.9. Examples of Zeta Potential Changes.- 7.10. Utility of Electrical Double-Layer and Electrokinetic Data.- 7.11. Selected Readings.- 8. Adsorption of Flotation Collectors.- 8.1. Requirements for Collector Adsorption.- 8.2. Mechanisms of Xanthate Adsorption.- 8.2.1. The Nature of the Adsorbate Species.- 8.2.2. The Critical Role of Oxygen in Sulfide Flotation Systems.- 8.2.3. Flotation Problems Caused by Excessive Surface Oxidation.- 8.3. Mechanisms of Adsorption of Non-Thio Collectors.- 8.3.1. Chemisorption of Carboxylates Accompanied by Physical Coadsorption.- 8.3.2. Molecular Interactions Among Surfactants at Solid/Liquid Interfaces.- 8.3.3. Specific Adsorption of Ionized Collector Species in the IHP (Without Charge Transfer).- 8.3.4. Adsorption of Surfactants to a Network of Polymerized Counterion Complexes, Activating Agents.- 8.4. Adsorption of Surfactants to Highly Soluble Salts in Their Saturated Salt Solutions.- 8.5. Adsorption of Surfactants Leading to Suppression of Floatability.- 8.6. Concluding Remarks on Adsorption Mechanisms.- 8.7. Selected Readings.- 9. Flotation Froths and Foams.- 9.1. Single Gas Bubbles in Liquid.- 9.2. Foams and Froths (Two-Phase Systems).- 9.3. Kinetics of Drainage in Single Films Supported on Frames.- 9.4. Characteristics of Single Thin Liquid Layers (Thin Films). Disjoining Pressure.- 9.5. Theories of Foam and Froth Stability.- 9.6. Destruction (Collapse) of Foams and Froths.- 9.7. Theoretical Conditions (From Analysis of Film Thinning) for Particle-Bubble Attachment (Mineralization of Bubbles)..- 9.7.1. Effects of Surfactants on Induction Time in Particle-Bubble Attachment.- 9.7.2. The Role of Surfactants and Their Diffusion in Particle-Bubble Attachment.- 9.7.3. Withdrawal of Water To Establish the Area of Particle-Bubble Contact.- 9.8. Joint Action of Collectors and Frothers in Flotation.- 9.9. Flotation Frothers: Their Requirements and Mechanisms of Their Action.- 9.10. Mineralized Flotation Froths and Their Stability.- 9.11. Bubble Generation in Mechanical Flotation Cells.- 9.12. Selected Readings.- 10. Inorganic Regulating Agents, Activators, Depressants.- 10.1. pH Control.- 10.2. Control of Charge Density at the Solid/Liquid Interface.- 10.2.1. Sodium Silicate.- 10.2.2. Sodium Polyphosphates.- 10.3. Additives Regulating the Oxidation States of Various Components in the Pulp.- 10.4. Complexing Additives.- 10.5. Hydro Complexes.- 10.5.1. Selective Flotation Using Control of pH.- 10.6. Complexing Additives Containing Sulfide, Sulfite, or Thiosulfate Ions.- 10.6.1. Use of Sulfur-Containing Inorganic Additives in Selective Flotation.- 10.7. Cyanides, Cyanates, Thiocyanates, and Ferrocyanates.- 10.8. Use of Cyanide Ion as a Depressant.- 10.9. Halide Ligands.- 10.10. Closing Remarks-Problems Created by Fine Particles.- 10.11. Selected Readings.- References.