Small-Scale Steelmaking

186 Pages·1983·3.858 MB·English

by  W. K. V. Gale (auth.), R. D. Walker (eds.)

SMALL-SCALE STEELMAKING
SMALL-SCALE
STEELMAKING
Edited by
R. D. Walker
Department of Metallurgy and Materials Science,
University College, Cardiff, UK
APPLIED SCIENCE PUBLISHERS
LONDON and NEW YORK
APPLIED SCIENCE PUBLISHERS LTD
Ripple Road, Barking, Essex, England
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ELSEVIER SCIENCE PUBLISHING CO., INC.
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British Library Cataloguing in Publication Data
Small-scale steelmaking.
1. Steel
I. Walker, R. D.
669: 142 TS305
ISBN-13: 978-94-011-6372-9 e-ISBN-13: 978-94-011-6370-5
DOl: 10.1 007/978-94-011-6370-5
WITH 9 TABLES AND 57 ILLUSTRATIONS
© APPLIED SCIENCE PUBLISHERS LTD 1983
Softcover reprint of the hardcover 1s t edition 1983
The selection and presentation of material and the opinions expressed in this
publication are the sole responsibility of the authors concerned
All rights reserved. No part of this publication may be reproduced, stored
in a retrieval system, or transmitted in any form or by any means,
electronic, mechanical. photocopying, recording, or otherwise, without
the prior written permission of the copyright owner, Applied Science
Publishers Ltd, Ripple Road, Barking, Essex, England
Photoset in England by Keyset Composition, Colchester
Preface
The contents of this volume cover all the major activities associated with
small-scale steelmaking in mini-steelworks (except Direct Reduction, on
which two comprehensive volumes have recently appeared - see refs 11 &
12, Chapter 2). There is, of course, an immediate problem of agreeing on a
suitable definition of mini-steelworks and the entrepreneurial nature of
many businesses based on the mini-steelplant route compounds this
problem. Nevertheless, as is shown by the lucid review in the opening
chapter, it is quite possible to derive a working definition of a mini
steelworks.
The succeeding chapters deal with steelmaking in a linear fashion; a
survey of raw materials supply being followed by independent analyses of
arc furnace practice, casting and rolling. The volume is rounded off by a
consideration of the important topics of energy costs and environmental
factors.
As anyone associated with iron and steelmaking well knows, the indus
try is not the exclusive preserve of the metallurgist, although he plays a
prominent role in its activities. For this reason, it is hoped that the level of
treatment will commend the book to a wide readership. that includes
non-metallurgical professionals in plant management and elsewhere, as
well as industrial metallurgists. Lecturers in universities, polytechnics and
colleges of further education should find this volume useful as a course
reader for final year and postgraduate studies of steelmaking.
Mini-steelworks are employed in almost every important steelmaking
country in the world, except those in the Comecon system, where only a
few such plants have been constructed so far. By way of contrast,
developing countries new to steelmaking have proved to be fertile ground
for this kind of operation and the book addresses itself to their circum
stances, as well as to those of the established producers.
R.D. WALKER
v
Acknowledgements
The editor wishes to thank the following organisations for permission to
reproduce illustrations from previous pUblications: British Steel Corpor
ation-Fig. 1.2; Concast AG, Zurich-Fig. 1.3; Birds Shredded Products
Ltd, Cardiff-Figs 2.1, 2.2, 2.3, 2.5, and 2.6; The Metals Society-Fig.
4.12; Fuel and MetallurgicalJournals Ltd-Fig. 6.7.
A number of other figures in the book are based on already published
material and, in these cases, an appropriate acknowledgement appears in
the caption.
Finally, thanks are due to Frances Matthews, Maureen Ellis and Eileen
Ridout for typing assistance.
vii
Contents
PREFACE............................................... v
ACKNOWLEDGEMENTS ................................ VB
LIST OF CONTRIBUTORS............................... xv
1 ORIGINS AND DEVELOPMENT OF SMALL-SCALE
STEELMAKING. ByW. K. V. Gale ........................ 1
1.1 The Mini-Steelworks-What is it? ...................... 1
1.2 Equipment for Mini-Steelworks-An Historical Perspective 4
1.3 Mini-Steelworks in the 1960s and Later ................. 6
1.4 Technological Developments .......................... 11
1.5 Future Prospects .................................... 16
References ............................................. 19
2 ARC FURNACE FEEDSTOCK. By D. M. Headworth and R.
D. Walker. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.1 Introduction ........................................ 21
2.2 Influence of Process Route and Other Factors on Scrap
Availabilityl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.3 The Origins of Steel and Cast Iron Scrap ................ 23
2.3.1 Major scrap categories ........................... 23
2.3.2 Scrap from dismantling and demolition ............. 25
2.3.3 Scrap from'shipbreaking .......................... 25
2.3.4 Scrap arising from old cars, refrigerators and washing
machines ....................................... 26
2.4 Scrap Preparation Plant and Associated Equipment . . . . . . . 27
IX
x SMALL-SCALE STEELMAKING
2.4.1 General remarks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.4.2 Scrap shearing and baling. . . . . . . . . . . . . . . . . . . . . . . . . 27
2.4.3 Scrap fragmentation and shredding ................ 30
2.4.4 Fragmentising equipment and practice. . . . . . . . . . . . . . 32
2.4.5 Economics of scrap processing .................... 35
2.5 Technical Specification for Ferrous Scrap. . . . . . . . . . . . . . . . 36
2.6 Influence of Residuals on Steelmaking Practice. . . . . . . . . . . 37
2.7 Other Sources of Iron. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
2.7.1 Directly reduced (DR) iron ....................... 39
2.7.2 Granulated and plate iron from the blast furnace. . . . . . 40
2.8 Other Materials ..................................... 41
2.8.1 Deoxidisers and alloying additions .................. 41
2.8.2 Flux additions ................................... 42
2.8.3 Oxygen ......................................... 42
References ............................................. 42
3 ELECTRIC ARC FURNACES IN MINI-STEELPLANTS. By
N. H. McBroom .......................................... 45
3.1 Introduction ....................................... 45
3.2' Scope ............................................. 47
3.3 Electrical Requirements ............................. 49
3.4 Furnace Design .................................... 53
3.5 Water-Cooled Panels ............................... 55
3.6 Computer Control of Electric Arc Melting Operations ... 56
3.7 Oxy-Fuel Burners .................................. 60
3.8 Scrap Preheating ................................... 61
3.9 Continuous Feeding ................................ 62
3.10 Foaming Slag ...................................... 64
3.11 De-Oxidation Practice .............................. 64
3.12 Performance Criteria ............................... 66
3.13 Ladle Refining ..................................... 67
3.14 Steels Produced in the Mini-Plant Arc Furnace .......... 74
3.15 The Future of the Arc Furnace in the Mini-Steelplant .... 75
References ............................................. 80
4 CASTING METHODS. By J. D. Sharp .................... 81
4.1 Introduction ....................................... 81
4.2 Choice of Casting Route ............................ 82
4.2.1 The finished product ., . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
CONTENTS xi
4.2.2 Cast weight ..................................... 83
4.2.3 The finance available ............................. 84
4.2.4 Plant location ................................... 84
4.3 The Ladle ......................................... 85
4.3.1 Ladle structure .................................. 85
4.3.2 Ladle refractories ................................ 86
4.3.3 Ladle drying .................................... 88
4.3.4 Teeming control ................................. 88
4.4 Ingot Casting ...................................... 92
4.4.1 The moulds ..................................... 92
4.4.2 Teeming methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
4.4.3 The ingot ....................................... 98
4.5 Continuous Casting ................................. 100
4.5.1 A brief history .................................. 100
4.5.2 Continuous casting today ......................... 100
4.5.3 Principles of operation ........................... 101
4.5.4 Continuous casting equipment. . . . . . . . . . . . . . . . . . . . . 102
4.5.5 Operation of continuous casting plants .............. 107
4.6 In-Line Rolling .................................... 109
4.6.1 Present applications .............................. 109
4.6.2 Metallurgical considerations of in-line rolling. . . . . . . . . 110
4.7 Horizontal Continuous Casting ....................... 110
4.7.1 Principles of operation ........................... 111
4.7.2 Operational advantages. . . . . . . . . . . . . . . . . . . . . . . . . . . 112
4.7.3 Present applications. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . 112
References ............................................. 113
5 ROLLING MILLS FOR MINI-STEELPLANTS. By J. D.
Sharp.. ... .... .... ....................................... 115
5.1 Introduction ....................................... 115
5.2 Product Classification ............................... 116
5.2.1 Rod and bar products ............................ 116
5.2.2 Section products ........................ ,. . . . . . . . 117
5.2.3 Flat products .................................... 117
5.2.4 Alloy steel products. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
5.3 The Steel Stock .................................... 118
5.4 Heating ofthe Steelfor Rolling ....................... 119
5.4.1 Design criteria .................................. 119
5.4.2 Types of reheating furnace. ... . . . ... . . . . . . . . . . . . . . 122
5.5 Mill Layouts for Small-Scale Steelmaking .............. 125
xii SMALL-SCALE STEELMAKING
5.5.1 Cross-country mills .............................. 125
5.5.2 Semi-continuous mills ............................ 127
5.5.3 Continuous mills. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
5.5.4 Individual mill stands ............................ 130
5.6 Roller Tables, Cooling Beds and Coilers .............. 132
5.6.1 Coilers ......................................... 133
5.7 Shears and Saws ................................... 134
5.8 Mill Rolls ......................................... 136
5.8.1 Cast iron rolls ................................ " . 136
5.8.2 Steel base rolls .................................. 137
5.8.3 Cast steel rolls .................................. 137
5.8.4 Forged steel rolls ................................ 137
5.8.5 Carbide rolls .................................... 138
5.8.6 Roll selection for a small semi-continuous mill ........ 138
5.8.7 Roll maintenance ................................ 138
5.9 Mill Guides ........................................ 139
5.10 Pass Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
5.11 Mill Drives ........................................ 142
5.12 High Reduction Mills ............................... 143
5.12.1 Advantages of high reduction systems .............. 144
5.12.2 Forge systems .................................. 145
5.12.3 Roll forging systems ............................ 146
5.12.4 Roll systems ................................... 146
References ............................................. 148
6 ENERGY REQUIREMENTS AND ENVIRONMENTAL
CONSTRAINTS. By R. D. Walker .......................... 149
6.1 Introduction ....................................... 149
6.2 Overall Energy Requirements for Steelmaking .......... 149
6.2.1 Energy losses in electricity supply .................. 153
6.2.2 In-plant energy losses ........................... . . 154
6.2.3 Energy-saving techniques ......................... 158
6.2.4 Continuous casting and energy saving ............... 159
6.2.5 Energy consumption in direct reduction ............. 161
6.3 Steelmaking and the Environment .................... 164
6.3.1 Particulate and gaseous emissions.. . .. . .. . . . . . . . . . . 164
6.3.2 Dust and fume containment systems ............... 166
6.3.3 Gas cleaning equipment .......................... 168
6.3.4 Water treatment ................................. 169
CONTENTS xiii
6.3.5 Solid wastes disposal ............................. 169
6.3.6 Noise .......................................... 170
References ............................................. 172
INDEX.................................................. 175