Rate Processes of Extractive Metallurgy PDF
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Rate Processes of Extractive Metallurgy Rate Processes of Extractive Metallurgy Edited by Hong Yong Sohn and Milton E. Wadsworth University of Utah Salt Lake City, Utah Plenum Press • New HJrk and London Library of Congress Cataloging in Publication Data Main entry under title: Rate processes of extractive metallurgy. Includes bibliographical references and index. 1. Metallurgy. I. Sohn, Hong Yong. II. Wadsworth, Milton E. TN665.R27 669 78-15941 ISBN 978-1-4684-9119-7 ISBN 978-1-4684-9117-3 (eBook) DOl 10.1007/978-1-4684-9117-3 © 1979 Plenum Press, New York A Divison of Plenum Publishing Corporation 227 West 17th Street, New York, N.Y. 10011 Softcover reprint of the hardcover 1st edition 1979 All rights reserved No part of this book may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher Contributors Robert W. Bartlett, Stanford Research Institute, Menlo Park, California; formerly Kennecott Research Center, Salt Lake City, Utah Ivan B. Cutler, Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah James W. Evans, Department of Materials Science and Mineral Engineering, University of California, Berkeley, California John A. Herbst, Department of Metallurgy and Metallurgical Engineering, University of Utah, Salt Lake City, Utah C.-H. Koo, Department of Materials Science and Mineral Engineering, University of California, Berkeley, California Sanaa E. Khalafalla, Twin Cities Metallurgy Research Center, U.S. Bureau of Mines, Twin Cities, Minnesota Jan D. Miller, Department of Metallurgy and Metallurgical Engineering, University of Utah, Salt Lake City, Utah Charles H. Pitt, Department of Metallurgy and Metallurgical Engineering, University of Utah, Salt Lake City, Utah Hong Yong Sohn, Department of Metallurgy and Metallurgical Engineering, University of Utah, Salt Lake City, Utah Julian Szekel" Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts E. T. Turkdogan, Research Laboratory, U.S. Steel Corporation, Monroeville, Pennsylvania Milton E. Wadsworth, Department of Metallurgy and Metallurgical Engineering, University of Utah, Salt Lake City, Utah v Preface Computer technology in the past fifteen years has essentially rev olutionized engineering education. Complex systems involving coupled mass transport and flow have yielded to numerical analysis even for relatively complex geometries. The application of such technology together with advances in applied physical chemistry have justified a general updating of the field of heterogeneous kinetics in extractive metallurgy. This book is an attempt to cover significant areas of extrac tive metallurgy from the viewpoint of heterogeneous kinetics. Kinetic studies serve to elucidate fundamental mechanisms of reac tions and to provide data for engineering applications, including improved ability to scale processes up from bench to pilot plant. The general theme of this book is the latter-the scale-up. The practicing engineer is faced with problems of changes of order of magnitude in reactor size. We hope that the fundamentals of heterogeneous kinetics will provide increasing ability for such scale-up efforts. Although ther modynamics is important in defining potential reaction paths and the end products, kinetic limitations involving molecular reactions, mass trans port, or heat flow normally influence ultimate rates of production. For this reason, rate processes in the general field of extractive metallurgy have been emphasized in this book. This book is an edited version of the notes for an intensive short course of the same title held at the University of Utah in 1975. The section on oxide reduction was added subsequently. Although various chapters and sections are contributions by different authors, we selected and organized the topics so that coherence and continuity were pre served as far as possible. There are some slight differences in the notation in the various sections, but in such cases the symbols are defined where they first appear in a given section. We wish to thank all those who have helped in making the short course possible and in the preparation of this book. While we cannot vii lliii Preftu:e possibly name all of them, we would like to mention the following: We gratefully acknowledge the support of the Kennecott Copper Corpora tion, the U.S. Steel Corporation, and the U.S. Bureau of Mines, and the encouragement and assistance of Dr. K. J. Richards of Kennecott Research Center. Professor Henry Eyring of the University of Utah, a pioneer in the field of chemical kinetics, delivered a keynote lecture on the subject of "Reaction-Rate Theory and Some Applications." Professor Julian Szekely of the Massachusetts Institute of Technology deserves thanks for introducing one of us (HYS) to extractive and process metal lurgy and for instilling in him an "erroneous" idea, through his many short courses and conferences, that a short course of this type is an easy venture. Professors R. D. Pehlke (University of Michigan) and T. J. O'Keefe (University of Missouri-Rolla) offered encouragement and support of our effort and made valuable suggestions regarding the contents of the book. The inception of the short course was a result of the combined efforts by our colleagues in the Department of Metallurgy and Metal lurgical Engineering, University of Utah. We also thank the participants of the short course for providing lively discussions during the sessions and helpful comments afterward. Our warmest thanks go to our secretarial staff for typing much of the manuscript and assisting us in many ways with its preparation. H. Y. Sohn M. E. Wadsworth Contents 1. Fundamentals of the Kinetics of Heterogeneous Reaction Systems in Extractive Metallurgy H. Y. Sohn 1.1. Elementary Steps ................... 1 1.1.1. Mass Transfer between a Solid Surface and a Fluid 3 1.1.2. Diffusion of Fluid Species through the Pores of a Solid 4 1.1.3. Intrinsic Kinetics of Heterogeneous Reactions on Solid Surfaces . . . . . . . . . . . . . . . . . . . . . 5 1.1.4. Heat Transfer between a Solid Surface and a Moving Fluid Stream ............. 6 1.1.5. Conduction of Heat in Porous Solids 7 1.1.6. Summary ............ 7 1.2. Reaction of a Single Nonporous Particle 8 1.2.1. Reactions in Which No Solid Product Layer Is Formed 8 1.2.2. Reactions in Which a Product Layer Is Formed 11 1.2.3. Nonisothermal Reactions in Shrinking-Unreacted-Core Systems . . . . . . . . . . 17 1.2.4. Summary and Comments . . . . . . . . . . 22 1.3. Reaction of a Single Porous Particle ... . . . . . 23 1.3.1. Reactions in Which No Solid Product Is Formed 24 1.3.2. Reactions in Which a Product Layer Is Formed 30 1.3.3. Concluding Remarks . . . . . . . . . . . . 37 1.4. Reactions between Two Solids Proceeding through Gaseous Intermediates ...... 38 1.4.1. Formulation of Model 40 1.4.2. Results 43 1.4.3. Discussion 47 1.5. Notation 47 References 49 j" Contents " 2. Rate Processes in Multiparticle Metallurgical Systems J. A. Herbst 2.1. General Approach to Describing Rate Processes in Multiparticle Systems . . . . . 53 2.1.1. Introduction . . . . . . 53 2.1.2. Motivation ...... 54 2.1. 3. Particle Characterization 61 2.1.4. Representation of Property Distributions 63 2.1.5. Population-Balance Framework 74 2.1.6. Application of Population Balance to Extractive Metallurgical Systems . . . . . . . . . 81 2.1.7. Summary and Conclusions 110 References ........ 111 2A. Chemical Process Analysis and Design for Multiparticle Systems Robert W. Bartlett 2A.1. Introduction ................ . 113 2A.2. The Concept of General Reactor Scale-up Criteria 114 2A.2.1. Particle Phenomenological Kinetics 115 2A.2.2. Rate-Controlling Steps in Particle Reactions 116 2A.2.3. Particle Size Distribution ........ . 118 2A.2.4. Residence Time Distribution in the Reactor 119 2A.3. Computed Dimensionless Design Curves 119 2A.4. Application of F Curves in Process Design 127 2A.4.1. Determining the Kinetic Data 127 2A.4.2. Scale-up 128 2A.4.3. Discussion 128 2A.5. Application Examples 129 References ..... 131 S. Hydrometallurgical Processes Sec. 3.1. Milton E. Wadsworth Sec. 3.2. Milton E. Wadsworth Sec. 3.3. J. D. Miller 3.1. Principles of Leaching (MEW) ................ 133 3.1.1. Introduction . . . .. ................ 133 3.1.2. Heterogeneous Kinetics of Importance in Hydrometallurgy 136 3.1.3. Leaching of Metals . 172 3.1.4. Leaching of Sulfides ........ 179 3.1.5. Leaching. of Oxides ........ 182 3.2. Dump and In Situ Leaching Practices (MEW) 186 3.2.1. Introduction . . . . . . . . . . . . 186 Contents xi 3.2.2. Leaching Systems 187 3.2.3. Rate Processes 189 3.3. Cementation (JDM) 197 3.3.1. Electrochemical Reactions 198 3.3.2. Mass Transfer-Hydrodynamics 210 3.3.3. Surface Deposit Effects 226 References 241 4. Pyrometallurgical Processes Sec. 4.1. S. E. Khaiafalla Sec. 4.2. J. W. Evans and C.-H. Koo Sec. 4.3. H. Y. Sohn and E. T. Turkdogan Sec. 4.4. I. B. Cutler Sec. 4.5. E. T. Turkdogan Sec. 4.6. C. H. Pitt 4.1. Roasting as a Unit Process (SEK) 245 4.1.1. Introduction . . . 245 4.1.2. Roasting Operations and Furnaces 247 4.1.3. Thermodynamics of Roasting Reactions 250 4.1.4. Gas-Solid Reactions in Roasting . . . . 253 4.1.5. Kinetics of Roasting Reactions . . . . . 254 4.1.6. Selected Cases in Metallurgical Roasting 262 4.2. The Reduction of Metal Oxides (JWE and CHK) 285 4.2.1. Introduction . . . . . 285 4.2.2. Iron Ore Reduction 286 4.2.3. Nickel Oxide Reduction 303 4.2.4. Lead Oxide Reduction 3 13 4.2.5. Reduction of Other Oxides by Gases 314 4.2.6. Reduction of Oxides by Solid Carbonaceous Materials 314 4.2.7. Di rect Red uction Processes 3 15 4.3. Calcination (HYS and ETT) 321 4.4. Sintering (!Be) ..... 329 4.4.1. Introduction . . . . 329 4.4.2. The Driving Force for Sintering 329 4.4.3. Stages of Sintering . . . . . . 330 4.4.4. Variables That Change Sintering Characteristics of Materials 335 4.4.5. Interaction between Grain Growth and Densification 338 4.4.6. Relationship of Strength to Densification by Sintering 338 4.4.7. Application of Principles of Sintering to Extractive Metallurgical Operations 339 4.5. Smelting and Refining (ETT) . . . . . . . . . . . . . 340 4.5.1. Introduction . . . . . . . . . . . . . . . . . . 340 4.5.2. Selected Properties of Gases, Liquid Metals, Mattes, and Slags ....................... 341
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