Table Of ContentTitles of Related Interest—
Ashby ENGINEERING MATERIALS 1
Ashby ENGINEERING MATERIALS 2
Brook IMPACT OF NON-DESTRUCTIVE TESTING
Koppel AUTOMATION IN MINING, MINERAL AND METAL PROCESSING 1989
Ruhle METAL-CERAMIC INTERFACES
Taya METAL MATRIX COMPOSITES
Other CIM Proceedings Published by Pergamon
Bergman FERROUS AND NON-FERROUS ALLOY PROCESSES
Bickert REDUCTION AND CASTING OF ALUMINUM
Chalkley TAILING AND EFFLUENT MANAGEMENT
Closset PRODUCTION AND ELECTROLYSIS OF LIGHT METALS
Dobby PROCESSING OF COMPLEX ORES
Embury HIGH TEMPERATURE OXIDATION AND SULPHIDATION PROCESSES
Jaeck PRIMARY AND SECONDARY LEAD PROCESSING
Jonas DIRECT ROLLING AND HOT CHARGING OF STRAND CAST BILLETS
Kachanlwsky IMPACT OF OXYGEN ON THE PRODUCTIVITY OF NON-FERROUS
METALLURGICAL PROCESSES
Lalt F. WEINBERG INTERNATIONAL SYMPOSIUM ON SOLIDIFICATION
PROCESSING
Macmillan QUALITY AND PROCESS CONTROL IN REDUCTION AND CASTING
OF ALUMINUM AND OTHER LIGHT METALS
Mostaghacl PROCESSING OF CERAMIC AND METAL MATRIX COMPOSITES
Plumpton PRODUCTION AND PROCESSING OF FINE PARTICLES
Purely FUNDAMENTALS AND APPLICATIONS OF TERNARY DIFFUSION
Rigaud ADVANCES IN REFRACTORIES FOR THE METALLURGICAL INDUSTRIES
Ruddle ACCELERATED COOLING OF ROLLED STEEL
Salter GOLD METALLURGY
Thompson COMPUTER SOFTWARE IN CHEMICAL AND EXTRACTIVE
METALLURGY
TWIgge-Molecey MATERIALS HANDLING IN PYROMETALLURGY
IWigge-Molecey PROCESS GAS HANDLING AND CLEANING
TVson FRACTURE MECHANICS
Wilkinson ADVANCED STRUCTURAL MATERIALS
Related Journals
(Free sample copies available upon request)
ACTA METALLURGICA
CANADIAN METALLURGICAL QUARTERLY
MATERIALS RESEARCH BULLETIN
MINERALS ENGINEERING
SCRIPTA METALLURGICA
Titles of Related Interest—
Ashby ENGINEERING MATERIALS 1
Ashby ENGINEERING MATERIALS 2
Brook IMPACT OF NON-DESTRUCTIVE TESTING
Koppel AUTOMATION IN MINING, MINERAL AND METAL PROCESSING 1989
Ruhle METAL-CERAMIC INTERFACES
Taya METAL MATRIX COMPOSITES
Other CIM Proceedings Published by Pergamon
Bergman FERROUS AND NON-FERROUS ALLOY PROCESSES
Bickert REDUCTION AND CASTING OF ALUMINUM
Chalkley TAILING AND EFFLUENT MANAGEMENT
Closset PRODUCTION AND ELECTROLYSIS OF LIGHT METALS
Dobby PROCESSING OF COMPLEX ORES
Embury HIGH TEMPERATURE OXIDATION AND SULPHIDATION PROCESSES
Jaeck PRIMARY AND SECONDARY LEAD PROCESSING
Jonas DIRECT ROLLING AND HOT CHARGING OF STRAND CAST BILLETS
Kachanlwsky IMPACT OF OXYGEN ON THE PRODUCTIVITY OF NON-FERROUS
METALLURGICAL PROCESSES
Lalt F. WEINBERG INTERNATIONAL SYMPOSIUM ON SOLIDIFICATION
PROCESSING
Macmillan QUALITY AND PROCESS CONTROL IN REDUCTION AND CASTING
OF ALUMINUM AND OTHER LIGHT METALS
Mostaghacl PROCESSING OF CERAMIC AND METAL MATRIX COMPOSITES
Plumpton PRODUCTION AND PROCESSING OF FINE PARTICLES
Purely FUNDAMENTALS AND APPLICATIONS OF TERNARY DIFFUSION
Rigaud ADVANCES IN REFRACTORIES FOR THE METALLURGICAL INDUSTRIES
Ruddle ACCELERATED COOLING OF ROLLED STEEL
Salter GOLD METALLURGY
Thompson COMPUTER SOFTWARE IN CHEMICAL AND EXTRACTIVE
METALLURGY
TWIgge-Molecey MATERIALS HANDLING IN PYROMETALLURGY
IWigge-Molecey PROCESS GAS HANDLING AND CLEANING
TVson FRACTURE MECHANICS
Wilkinson ADVANCED STRUCTURAL MATERIALS
Related Journals
(Free sample copies available upon request)
ACTA METALLURGICA
CANADIAN METALLURGICAL QUARTERLY
MATERIALS RESEARCH BULLETIN
MINERALS ENGINEERING
SCRIPTA METALLURGICA
PROCEEDINGS OF THE INTERNATIONAL SYMPOSIUM ON
EXTRACTION, REFINING AND FABRICATION OF LIGHT METALS,
OTTAWA, ONTARIO, AUGUST 18-21, 1991
Extraction, Refining, and
Fabrication of Light Metals
Editors
Mahi Sahoo
CANMET
Ottawa, Ontario
Peter Pinfold
Norsk Hydro Canada Inc.
Becancour, Quebec
Symposium organized by the Light Metals Section of The Metallurgical Society of CIM
30th ANNUAL CONFERENCE OF METALLURGISTS OF CIM
30e CONFERENCE ANNUELLE DES M E T A L L U R G I E S DE LTCM
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All rights reserved. No part of this publication may
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1984
Session Chairmen
Aspects of Magnesium Technology
M. Sahoo M. Avedesian
CANMET Institute of Magnesium Technology
Ottawa, Ontario Ste-Foy, Quebec
Light Metal Matrix Composites
B. Closset J. Masounave
Timminco Metals ETS, Universite du Quebec a Montreal
Toronto, Ontario Montreal, Quebec
Aspects of Light Metals Reduction Technology
L. Larouche C. Bickert
Canadian Reynolds Metals Co. Ltd. Pechiney Corp.
Baie Comeau, Quebec Greenwich, Connecticut, U.S.A.
Casting and Solidification of Aluminum Base Alloys
P. Pinfold P. Tremblay
Norsk Hydro Canada Inc. Arvida R&D Centre, Alcan International Ltd.
Becancour, Quebec Jonquiere, Quebec
Mathematical Modelling and Computer Simulation
R. Guthrie M. Bouchard
McGill University Universite du Quebec a Chicoutimi
Montreal, Quebec Chicoutimi, Quebec
Melting, Alloying and Properties of Light Metals
P. Aylen P. Pinfold
Alumax Inc. Norsk Hydro Canada Inc.
Montreal, Quebec Becancour, Quebec
v
Foreword
The Light Metals Section of the Metallurgical Society of CIM has been organizing international
symposia for the last three years on advances in different aspects of light metals technology
during the Annual Conference of Metallurgists.
This year in conjunction with the 30th Annual Conference of Metallurgists of CIM, the Light
Metals Section is proud to present its Fourth International Symposium on "Extraction, Refin-
ing and Fabrication of Light Metals". World-class scientists and engineers from more than six
countries are presenting over thirty papers on topics such as magnesium casting technology,
metal matrix composites, mathematical modelling, solidification, and reduction of light metals.
In view of Canada's recent emergence as an important magnesium producer, a separate session
will be held to focus on the recent advances in magnesium technology.
Metal matrix composites are an important class of the advanced industrial materials and signifi-
cant advances have been achieved recently on the fabrication and characterization of their micro-
structures and mechanical properties. The session on light metal matrix composites comprises
papers on some of these recent developments.
As the Symposium chairpeople, we wish to express our sincere thanks to all the authors for
preparing their manuscripts in time for publication, and for presenting their papers at the
Symposium.
One of us (M.S.) would like to acknowledge the assistance provided by Messrs. Peter Newcombe
and Bob Emmett in taking care of the preliminary planning and correspondence for the
Symposium announcements. Mr. Newcombe, in particular spent considerable time compiling
the addresses and preparing the technical program for the sessions. The moral support of the
management of the Metals Technology Laboratories of CANMET is also gratefully acknowledged.
August 1991 Mahi Sahoo
Peter Pinfold
Editors
vii
3
Production and applications of ultra high purity magnesium
S.G. Hibbins, F.C. Dimayuga
Timminco Metals, A Division of Timminco Limited, Haley, Ontario, Canada
INTRODUCTION
1
Timminco Metals Haley, Ontario facility has produced
magnesium metal and alloys since 1942. Under the guidance of Dr.
L.N. Pidgeon, this plant became the first commercialized
application of the classical Pidgeon Process for producing
magnesium metal (1,2,3,4). Today, this 800 acre facility is the
recognized leader in the production of the world's highest purity
magnesium metal and alloys.
Timminco has been responsible for significant advancements in
the production and application of light and reactive metals. The
original thermal magnesium process has been adapted to the
production of calcium and strontium metals. Research and
development has led to the introduction of such products as CAL-AL
and MAGCAL for use by the lead industry, a variety of strontium
products including a 90% Sr - 10% Al alloy for use by the aluminum
foundry industry and various granular and particulate magnesium and
calcium products. Timminco has made significant process
improvements over the years to increase automation and efficiency
of the silicothermic magnesium process and also to refine the
process to consolidate its status as producer of the highest purity
magnesium commercially available.
Today, Timminco Metals operates three production facilities
which are shown in Figure 1. The Haley plant remains the primary
source of magnesium metal and alloys, ingots, extrusions, granules
and particulates. The Westmeath plant, which was commissioned in
1987, is the source of strontium and calcium metal and special
alloys. The Beauharnois facility continues to supply 85% and 75%
ferrosilicon to Haley and a limited number of customers in the
steel industry. The unique nature of the metallothermic process
facilities enables Timminco to maintain a high degree of operating
flexibility with a variety of products being manufactured at either
the Haley or Westmeath plants, as circumstances require.
As a major part of the company's efforts to continuously
improve the quality and delivery of its products, Timminco has
implemented a comprehensive Quality Assurance Program which is
designed to meet and in some cases, exceed the requirements of the
Canadian Standard Z299.3 (5). As a result, Timminco's Westmeath
operations have been given a Ql Preferred Quality Supplier Award by
the Ford Motor Company.
4 EXTRACTION, REFINING AND FABRICATION OF LIGHT METALS
In recent years, Timminco has reaffirmed its commitment to
research and development, especially towards new process and
product development. In 1988, with the transfer of specialty
metals production to the Westmeath plant, investments have been
made at the 7500 square foot Haley Research facility, with the
installation of 3 new experimental melting furnaces and additional
small-scale vacuum furnace capacity. Timminco also has an active
out of house R & D programme, which has included research at
several universities, the Canada Centre for Mineral and Energy
Technology (CANMET) and the Institute of Magnesium Technology
(IMT).
TIMMINCO METALS
HALEY WESTMEATH BEAUHARNOIS
Integrated R&D
Magnesiuiim Pilot Plant
SmBeillt er
magnesium new products Sr + Ca ferrosilicon
metal S alloys; + processes products,
ingots, special alloys
extrusions,
granules
Figure 1 - Timminco Metals Facilities.
THE SILICOTHERMIC MAGNESIUM PROCESS
Process Description
In the production of magnesium by the Pidgeon silicothermic
process (Figure 2), high purity dolomite, quarried from an on-site
open pit, is crushed, classified and calcined. The burned dolomite
is subsequently mixed with a controlled amount of ferrosilicon
obtained from Timminco^ Beauharnois, Quebec ferroalloy plant. The
mixture is briquetted and charged to high-alloy steel retorts
contained in gas-fired furnaces.
Reduction is carried out under vacuum at about 1200°C according
to the following chemical reaction:
2MgO CaO + Si = 2Mg + 2CaO Si0 (1)
2
During this reaction, metallic magnesium is vaporized and
transported to a controlled temperature condenser where sublimation
takes place. After a specified period of time, the vacuum is
broken and the condensed "crown" of magnesium metal and the
dicalcium silicate slag are discharged from the retort. The
metallic crowns are subsequently processed to produce a variety of
pure metal and alloy products including ingots, billets,
sacrificial anodes, extrusions and granules.
EXTRACTION, REFINING AND FABRICATION OF LIGHT METALS 5
Reductant
Briquetting
Slag
Melt & Alloy
Ingots &
Extrusions
Package
Cut & Size
& Ship
Granulate
Chemical
Laboratory On-Line
f Computer Data Base
Figure 2 - Timminco s Metallothermic Vacuum Reduction Process.
Over the years, substantial progress has been made in automating
the Pidgeon process. Froats (4) outlined the advances which have
been implemented to improve the tooling for charging and
discharging the multiplicity of small units characteristic of the
process. Automated equipment was developed to distribute a
predetermined quantity of briquette charge in the horizontal
retorts prior to the vacuum reduction cycle. The technology to
remove hot spent residue by a vacuum pneumatic system was also
developed. By these developments, the laborious manual tasks of
charging briquettes and discharging residue were eliminated.
Since 1980, further improvements have been implemented in the
process, the most significant of these being:
upgrading of plant milling, mixing and briquetting
equipment, including improved, automatic control of raw
material batch weights.
conversion of electric retort furnace capacity to gas-
fired furnaces incorporating energy-efficient
regenerative burner technology.
implementation of statistical process control (SPC) in
all phases of plant operation, as part of a comprehensive
quality assurance program (5).
automation and streamlining of several downstream
operations, e.g., metal crown handling, granulating and
extrusion.
Metallurgical Efficiency
A significant body of knowledge has been developed at Timminco
on the metallurgy of the Pidgeon process (1,2,3,4). Operating
efficiency is dependent on such variables as temperature, vacuum,
cycle time, type of reductant, raw material sizing, briquette
density, retort alloy composition and dimensions.
6 EXTRACTION, REFINING AND FABRICATION OF LIGHT METALS
The roost significant factor affecting operating efficiency is
the relationship between magnesium reduction recovery and
ferrosilicon use. According to reaction (1), the stoichiometric
requirement is 0.577 kg Si per kg of Mg contained in the retort
charge. In practice, an excess of the stoichiometric amount is
necessary to obtain high Mg recovery. The excess amount must be
determined empirically, as no adequate theoretical prediction based
on the Fe-Si phase diagram can explain the optimum operating
region.
Plant operations can be run equally well using either 75% or
85% ferrosilicon, although at present, 85% ferrosilicon is
preferred due to slightly higher operating productivity. The
optimum operating condition is based on a combination of
ferrosilicon usage, magnesium recovery, ferrosilicon price,
production rate and other operating factors.
HIGH PURITY MAGNESIUM
Overview of Applications
Magnesium has a diversity of applications, as Figure 3 shows.
The main applications can be grouped as aluminum alloying, chemical
and structural uses. As shown, 52% of world magnesium shipments in
1990 were used in aluminum alloying. Chemical applications,
including nodular iron, steel desulphurization, metal reduction,
sacrificial anodes and Grignard reagents, accounted for about 27%
of magnesium consumption. Structural applications (die and gravity
casting, wrought products) were about 18% of world magnesium
consumption in 1990. Chemical applications account for most of the
consumption of higher purity magnesium. The development of high
purity magnesium alloys has alleviated many of the concerns related
to corrosion of magnesium in structural applications. The most
significant growth potential for magnesium consumption is expected
to be in magnesium casting alloys.
Aluminium
52%
Other
3%
Nodular Iron
Structural
Desulfurization
18%
11%
Chemical
10%
Total shipments 1990; 252.000 mt
Figure 3 - Primary Magnesium Shipment by Market Segment, 1990.
(Source IMA).
