The principles of copper smelting

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Preface

This book is written, in part, for students; and, as there are many persons who would like to gain some insight into the smelting of copper, but who have not the training which is requisite for the understanding of ordinary metallurgical treatises, 1 have tried to write in such a manner that it might be reasonably intelligible to those who have no exact knowledge of chemistry.

As is indicated by its title, the book deals mainly with the fundamental principles upon which methods are based, rather than with descriptions of processes or apparatus. These latter subjects may be found adequately treated in our standard works; but the study of the principles upon which the processes depend is accorded so little space, and is distributed through so much other material, in ordinary metallurgical literature, that a treatise devoted to the reasons why instead of to the means how will fill an existing gap, provided it is written in an acceptable manner.

In order to compress my subject within reasonable limits, I have omitted the greater part of such information ^s may be found in the standard works on the metallurgy of copper.

In the arrangement and material of the book I have followed, in the main, my courses of lectures given at the Graduate School of Applied Science, Harvard University ;'and if it be noticed that, throughout the text, business considerations are linked with scientific principles, I can only reply that this is also the case in actual life, and that the main object of a technical school is to fit young people to gain a livelihood by the application of scientific facts to commercial conditions. This aim is, in my judgment, best accomplished by giving them a thorough knowledge of the principles upon which rest the operations that they expect to employ. Some familiarity with the handling of tools and with general manipulation is also most important, though far inferior in practical utility to the kind of knowledge to which I have just alluded. A student can never learn to handle tods as well as a pot-puller does; and, if he could, he would never care to urilize iv PREFACE

this skill if he aspired to anything beyond the position of a pot-puller.

The development of pyrite smelting has been rapid and satisfactory during the past few years; and, while desiring to acknowledge fully the aid received from the work of Wright, Channing, Beardsley, Carpenter, Lang, Bretherton, Heywood, Fulton, and others, I must express particularly my obligations to Robert Sticht, general man^r of the Mount Lyell Mining and Railway Company, Limited. Mr. Sticht has, during the past three years, kept me thoroughly informed of his prc^esstve work at Mount Lyell, as well as of his own deductions therefrom. In the chapter on "Pyrite Smelting" 1 have translated and utilized a considerable portion of his late paper in MttdUurgie on the subject, and the proofs of the entire chapter have had the benefit of his criticism and additions.

The chapter on "Thermochemistry" was written for this book by Mr. Joseph W. Richards, professor erf metallurgy, Lehigh University.

1 am indebted to Mr. John L. Elliot, president of the Arizona Smelting Company, for permission to reproduce plans of the large oil-burning reverberatory furnaces at Humboldt, Arizona, and to Mr. Cyrus Robinson, consulting engineer of the Company, for the drawings and data.

Messrs, E, P..Mathewson of the Washoe smelter, H, L, Charles of the Montana Ore Purchasing Company, S. E. Bretherton of the Great Western Gold Company, the Colorado Iron Works Company of Denver, and many others, have aided me in the preparation of this book, and have my sincere thanks.

I have had the valuable aid of Prof. Joseph W. Richards of Lehigh, and of Assistant Prof. Charles H. White of Harvard in reading and correcting the chemical calculations which form so important a part of this work, as well as in criticising much of the text; and 1 wish especially to acknowledge the constant assistance of a member of my own family. Miss S. T. Cashing, in improving the English of the book.

Edward Dyer Peters.

CHAPTER I Methods and Collectobs

ClossiScatio)) of Methods; Wet Methods, i. Diy Methods, 3. Recovery of the Precious Metals; Collectors, 3.

CHAPTER II First Principus o» Smeltdto

Object of Smelting; Earthy and Metallic Portions of an Orr, 5. Degree of Concentration, 6. Smelting a Concentration Process, 7. Behaviorof Ores in the Blast Furnace; Iltustralion No. Onc.Q. Illustration No, Two, 11. Illustration No. Three, 13. Illustralion No.

CHAPTER III The Principles ot Roasting

Object of Roasting, 31. Essential Conditions, S3. Fundamental Reactions, 34. Change of Weight during Roasting, 35. Behavior of the individual Sulphides during Roasting, 18. Behavior of Arsenides and Antiinonides, 40. Behavior of the Earthy Min-

CHAPTER IV The Chemistry of Sueltino

Interior Phenooiena of the Blast Furnace; Fonnation of Slag and Hatte, 46. Illustrative Smelting Mixture, 49. The Use of Permanent Factors lor Simplifying Calculations, 55. The Three Laws of Matte Formation, 5S. Appoitioning of the Iron to Matte and Slag, 65. Comparison of Copper and Iron Blast Furnaces, 77.

CHAPTER V The Practice ot Roashno

Heap and Stall Roasting, 8j. Treatment ot Raw Sulphide Rnes, 83. Classification of Methods for Treating Fines, 87. Weight of Matte Produced in Smelting Raw Fines, 89. Smelted Unbni(uetled Raw Fines, 91. Degree of Pulveriiation Required for Roasting, 95. Development of the Roasting Furnace. 99. O'Harra Furnace, loi. Brown Furnace, 103. Parkes Furnace; McDougall Furnace, 105. Modificalims of the McDougall Furnace, 106. Pearce Turret Furnace, 107.

vi CONTENTS

Chapter VI Faqk

Blast Ftibnace Subltino 108-166

Classi&calion of Methods, loS. Results Obtained by Smelting Uaroasled Sulphides, 110. MeiAllurgical Losses, J13. Removal of Sulphur in Smelting with Coke, 114. Calculation of a Smelting Charge, iiS. Fuels, 141. Smelling of Oxidized Oies, 141. Development of ihe Blast Furnace, 147. Waler-jackels, 149- Modem Blast Furnaces, 153. Handling of Materials, 161. Flue-dust, 164. Blast, 165.

CHAPTER VII Reveiberatoiy Sueltino 167-31*

Characteristics of the Reverberalory, t68. Siw ot Hearth, Fire-box, and 5la(±, 170. Development of the Reverberatory, 173. Chemistry of the Reverberatoiy, 174. Former Reverberatory Practice, iSi. Modem Practice, 184. Grate Area, iSS. Draft, 191. Firihg and Grating, r94. Heat and Losses, 196. Use of Hot Ore, 300. Dropping and Leveling Charge, 201. Retention of Matte in Furnace. loi. Skinuning and Tapping, 207. Claying and Repairing, 108. Large Anaconda Furnaces, 109. Arizona Smelting Company's Oil-buming Furnaces, no.

Chapter VIII

Introduction, 313. Necessary Constituents of Ore, 214. Importance of Time-element, 317. Necesuty of Oiidation, 230. Behavior of Pyrite in Furnace, a2r. Behavior of Sulphur in Furnace, 313. Composition of Furnace Gases, 234. Non-oxidizing Atmosphere in Furnace, 330. Contrast between Pyrite Smelting and ordinary Roasting, 231. Formation of natural Boshes in Furnace, 334. Analogy between Pyrite Smelting and Bessemerizing, 336. Phenomena occurring within the Furnace, 337. Recapitulation of Changes undergone by Ore-chaiige, 341. Regulating the Degree of Coucentration, 343. Ctxnposltion of the Slags, 344. Earthy Bases, 345. Importance of jret Silica. 348. Relation between free Silica bthI Blast, 353. The Pyrite Furnace chooses its own Slag, 254. Amount of Blast determines Capacity of Furnace, 255. Silicate -degree of Slag conforms to Temperature of Focus, 356. Formation -temperature of various Silicates, 3jg. Study of Slag-formation during Pyrite Smelting, 264. Protection of Copper by Sulphur, 369. Composition of the Matte, 370. Mutual Solubility of Matte and Slag, 371 . Coke in Pyrite Smelting, 373. Thermal Calculations, 377. Effect of too much Silica in Charge. 283. Effect of too little Silica in Charge, 386. Effect of Silica on Degree of Concentration, i8q. Zones of Furnace-shaft, 291. Increase in Blast increases Capacity, 393. Influence of earthy Bases on Pyrite Smelting, 396. Silicate-degree of TJme in Slags, 397. Smelting n Google

CONTENTS vii

PAOE Process at Ml. Ljell, 302. Intensily of Cc»iibuBtiaii eiaential to Pyrite Smelting, 311. Alumina in Pyrite Smelting, 313. Blende, Heavy Spur, Galena, Arsenic, Antimony in Pyrite Smelting, 316. Hot and Cold Blast, 317. Costs at Mt. Lyell, 323. Partial Pyrite Smelting, 333, Orra suitable for Partial Fynte Smelting, 326. Composition of Slags suitable for Partial Pyrite Smelting, 328. Hot Blast in Partial Pyrite Smelting, 334. Proportion of Coke in Partial Pyrite Smelting, 335. Reconcentration of Matte by Pyrite Smelting, 336. Efficiency of U-pipe Stoves, 337.

CHAPTER IX A Practical S-tody of Slags 339-Aoo

Proportion of Base and Add In Slags, 340. Properties demanded in Copper Slags, 341. NomenclatNrc of Slags, 343. Oxygen-ratio of Slags, 34S- Replacement of Ferrous Oade with Lime, 346. Percentage of Oxygen in Slag Constituents, 347. Study of the Replacement-value o( Bases, 348. Practical Use of the Oxygen-n.tio of . SUgs, 363. Study of the Properties of the Type-slap, 368. Formation-temperature of the Type-slags, 374. Effect of replacing Ferrous Oxide with Manganous Oxide, 3S9. ESect of replacing Lime with Magnesia, 390. Effect of Zinc Oxide, 391. Effect of replacing Silica with Alumina; Effect of replacing Ferrous Oxide with Alumina, 394. Effect of replacing Lime with Alumina; Effect of icpladng Ferrous Oxide and Lime with Alumina, 395. Discussion of Alumitia Slags, 398. Ferric Oxide in Slags, 399.

Chapter X

Definition of Matte, 401. Behavior of Sulphides at Furnace Temperatures, 402. Gibb and Philip's Investigations upon the Composition of Mattes, 403. RUntgen's Investigations upon the Composition of Mattes, 410. Magnetic Oxide of Iron in Mattes, 413. Discussion oE Matte as a Collector for Gold and Silver, 414.

CHAPTER XI The Production o» Metaluc Copper from Matte .... 419-467 The Principles of Matte Concentration, 430. The Welsh Blister Process, 437. The Methods for separating the Predous Metals from Matte and frcm Metallic Copper, 441, The Besscmerizing of Copper Matte, 452. The Baggaley Method of Besscmerizing low-grade Matte in a basic-lined Converter, 463.

CHAPTER XII The HEiTODja of Copper 46S-494

Classes of Material submitted lo Refilling, 468. Effect of Impurities upon Copper, 470. Comparative Elimination of Impurities vHi CONTENTS

PAGE in diflerent Operadoiu, 475. Electrolytic Refining of Copper, 480. Furnace Refining of Copper, 4S5. Ellect of Cuprous Oxide upon Refined Copper, 491. Cause of Deterioratioi) of Copper from Over-poling, 49a.

CHAPTER Xlll

The Pbinoples of Furnace Buildino 495-5^9

Foundations, 495- Preparations for Building 498. Materials, 499, Mortars, joo. Fire-brick, 503. Red Brick, so4' Ironwork, 505. Labor, 508. Location of Furnaces, 509. Transportation of Materials, 510. Flue-dust, 515. A Discuseioa of Smeller Gases, and of the Means for Controlling them, 517. Manufacture of Sulphuric Acid from Smelter Gases. 517. UtUixation of the Sulphuric Add produced from Smelter Qases, 518.

Chapter XIV

Amount of Heat developed in [he Formation of Grides; of Sulphides, S33. Of Carbonates and Sulphates, 533. Heat of Formation from the Elements, 1:35. Heat of Formation in the Production of Silicates, 536. Theimochemistry of Roasting, 538. Calculation of Thermal Results during Roasting, 544. Calculation of Thermal Results during Matte Smelting, 547. Calculation of Tbennal Results during the Bessemerizing of Matte, 551.