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The history of gold begins in antiquity. Bits of gold were found in Spanish caves that were used by Paleolithic people around 40,000 B.C. Gold is the "child of Zeus," wrote the Greek poet Pindar. The Romans called the yellow metal aurum ("shining dawn"). Gold is the first element and first metal mentioned in the Bible, where it appears in more than 400 references. This book provides the most thorough and up-to-date information available on the extraction of gold from its ores, starting with the miner alogy of gold ores and ending with details of refining. Each chapter con cludes with a list of references including full publication information for all works cited. Sources preceded by an asterisk ( ) are especially recom mended for more in-depth study. Nine appendices, helpful to both students and operators, complement the text. I have made every attempt to keep abreast of recent technical literature on the extraction of gold. Original publications through the spring of 1989 have been reviewed and cited where appropriate. This book is intended as a reference for operators, managers, and designers of gold mills and for professional prospectors. It is also designed as a textbook for extractive metallurgy courses. I am indebted to the Library of Engineering Societies in New York, which was the main source of the references in the book. The assistance of my son, Panos, in typing the manuscript is gratefully acknowledged.

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1 Gold Ores.- Geochemistry of Gold and Auriferous Deposits.- Auriferous Deposits.- Effects of Biological Systems on Metallic Gold.- Gold in Sea Water.- Exploration for Gold.- 2 Physical and Chemical Properties of Gold.- Physical Properties of Gold.- Chemical Properties of Gold.- Gold Assaying.- 3 Treatment of Placer Deposits.- Placer Environment and Formation.- Dredging or Hydraulic Mining.- Gold Recovery from Placer Deposits.- Gravity Concentration of Alluvial Gold.- 4 Milling of Amenable Gold Ores.- Comminution of the Ore.- Partial Direct Recovery of Gold.- Leaching of Pulverized Gold Ores.- Gold Milling Flow Sheets.- Recovery of Gold from Solution.- 5 Treatment of Refractory Gold Ores.- Mineralogy of Refractory Gold Ores.- Flotation of Some Refractory Ores.- High-Temperature Oxidation: Roasting.- High-Pressure Oxidation.- Biological Oxidation.- Chemical Oxidation.- Silica-Locked Gold.- 6 Leaching Low-Grade Gold Ores.- Ore Testing.- Heap Leaching and Dump Leaching.- Vat Leaching.- 7 Recovery of Secondary Gold.- Base Metals Present in Gold Scrap.- Special Cases of Gold Scrap.- 8 Cyanidation of Gold Ores.- Theories on Gold Cyanidation.- The Mechanism of Cyanidation.- The Kinetics of Gold Cyanidation.- Cyanide Regeneration.- Destruction of Cyanide.- 9 Alternative Leaching Reagents for Gold.- Thiourea Leaching of Gold.- Thiosulfate Leaching of Gold.- Leaching with Halogens and Halides.- 10 Recovery of Gold from Solutions.- Zinc Cementation.- Activated Carbon Adsorption.- Electrowinning of Gold from Cyanide Solutions.- Electrowinning of Gold from Pregnant Gold-Mill Solutions.- Staged Heap Leaching and Direct Electrowinning.- Industrial Uses of Activated Carbon.- Ion-Exchange Resins.- Solvent Extraction.- Metal Chelating Agents.- 11 Melting and Refining of Gold.- The Wohlwill Electrorefining Process.- Gold Refining by Dissolution/Precipitation.- 12 Gold Mill Tailings.- Disposal of Tailings.- Water/Cyanide Recovery from Tailings Slurries.- Destruction of Cyanide in Gold-Mill Effluents.- Arsenic Removal from Gold-Mine Wastes.- Recovery of Gold from Accumulated Old Tailings.- Appendix A: Conversion Factors.- Appendix B: Gold Production Statistics.- Appendix C: Comparative Long-Term Total Production Costs in Selected Countries.- Appendix D: Primary Gold Deposits and Mines in the U.S..- Appendix E: Gold Mill Sampling and Metallurgical Balance.- Appendix F: Data Commonly Collected During Environmental Baseline Studies for an Environmental Assessment.- Appendix G: Flowchart of Gold Recovery from Copper Refinery Slimes.- Appendix H: Solubility of Minerals and Metals in Cyanide Solutions.

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