alternative technologies in iron and steelmaking

The 1994 Howe Memorial Lecture The Iron and Steel Society of AIME

Alternative Technologies in Iron and Steelmaking

PAUL E. NILLES

The first Howe Memorial Lecture, which was delivered 70 years ago, in 1924, was entitled "What is Steel?" This title may seem surprising in view of the very diversified use of steel already achieved at that time. It is obvious that the particular event constituted by the creation of this lecture invited the author to look back on what had been achieved and to try to forecast future developments.

The turn of the miIlenium, due in 6 years, induces similar initiatives in numerous fields. As far as the steel industry is concerned, some of the questions most frequently asked are as follows.

(1) How much steel will the world consume during the first part of the 21st century? (2) What are the raw material requirements and availabilities? (3) Which will be the geographical repartition of the production facilities? (4) What will be the optimum size and layout of a steel plant? (5) Will the future have large integrated steel plants?

During this lecture, I would like to address the following two topics.

(1) Are the present production technologies still appropriate or do new processes have to be developed for meeting the future needs of the steel industry?

(2) Which research strategy is required for bringing the new processes and new products to maturity and to industrial application?

Paul Nilles, Executive Director of the Centre de Recherches M~tallurgiques (Lirge, Belgium), received the Ing~nieur Civil M&al- lurgiste degree in 1958 and the Docteur en Sciences Appliqures in 1963 from the University of Liege. From 1960 to 1964, he served as Research Metallurgist at Centre de Recherches M&allurgiques (CRAM) and as Assistant at the University of Liege. From 1964 to 1971, Dr. Nilles was Head of the Steelmaking Department of CRM. During the years of 1971 through 1978, he was Manager of Steelmaking, Rolling Mill and User Properties Departments of CRM. From 1979 to 1989, he served as Director, Steel Branch of CRM, in charge of steelmaking, rolling, metal science, product development, and steel applications. Since 1990, he has been Executive Director and Member of the Board of CRAM. He has

published numerous articles on steetmaking, solidification, rolling, and product application.

Dr. Nilles" memberships include being Belgian representative on the Committee of Technology of IISI; distinguished member of the Iron and Steel Society of AIME; member of the Board of the Institute of Materials, London (1991 to 1994); member of the Verein Deutscher Eisen- hiittenleute; member of the Beirat of the Max-Planck-Instutut •r Eisenforschung (MPI); and member of the Iron and Steel Institute of Japan.

His distinctions include Chevalier de l'Ordre de la Couronne--Belgium; Charles Hetty Award 1973 (AIME)--United States; Colclough Medal and Prize 1982 (Institute of Metals)--United Kingdom; and Howe Memorial Lecturer 1994 (Iron and Steel Society of AIME).

METALLURGICAL AND MATERIALS TRANSACTIONS B VOLUME 27B. AUGUST 1996----541

160 106t

140

120

100

80

60

40

20

0 80 82 84 86 88 90 92 94

Year

Fig. 1--Steel production in Western Europe.

Number 180 . ~ ~ . ~

160 ~%,,,,/~ " " ~ , J l %~

140

v

80 50

60 i i ~ i i 40 1976 1980 1984 1988 1992 1996

Year

Fig. 2--Number of BFs and BOFs in operation in Western Europe.

B0F Crude steel production (106t) 100

90

80

70

60

I. NEEDS OF THE STEEL INDUSTRY

THE International Iron and Steel Institute (IISI), Brus- sels, in 1992, carried out a survey among its members, ask- ing which technology has to be developed in order to enable the steel industry to meet the market and social requirements at the beginning of the 21st century. {~]

This study concluded that two major demands have to be satisfied.

(1) The steel market will ask seemingly contradictory things of the steel industry, i.e., to deliver higher quality products at lower cost, to offer small lots in a variety of sizes and grades, and to observe short delivery times.

(2) Steelmakers must expect to face increasing constraints over environmental issues such as the minimization of emissions and effluents, the recovering and recycling of spent products, and the effective utilization of resources, by-products, and wastes.

In a global competition, the earnings of the steel industry tend to decrease rapidly under these constraints and new processes are needed to keep this industry profitable, while allowing it at the same time to satisfy the customer demands and to ensure the protection of the environment.

In this context, short-term and medium-term objectives must be distinguished.

(1) For the short term, it is important that the best presently available technologies are implemented rapidly and used efficiently.

(2) For the medium term, i.e., for the years 2000 to 2010, it appears that a certain number of new, alternative technologies have to be developed.

A. Short-Term Evolution of the Production Routes

In Western Europe, i.e., the European Union, Austria, and Scandinavia, crude steel production has remained fairly con- stant--around 148 million tonnes--since 1980 (Figure l).

The Blast Furnace/Basic Oxygen Furnace (BF/BOF) route still produces about two-thirds of the West European steel. The share of the electric arc furnace (EAF) has represented 30 pct of the production during the 1980s, and it has slightly increased during the past 3 years (32 pct in 1992). The EAF is taking over most of the long products from the integrated mills, which are concentrating more and more on flat products.

Which technologies have emerged recently and can be adopted rapidly to improve the efficiency of today's integrated and market mills?

1. Integrated mills For the integrated mills, the main short-term objectives

are as follows:

(a) to increase productivity, (b) to decrease the cost of raw materials, (c) to avoid environmental nuisances, and (d) to improve the quality and consistency of products.

Let us briefly comment on each of these goals.

(a) The productivity of large integrated steelworks has dra- matically increased during the past 10 years: Figure 2 shows that an almost unchanged BOF crude steel output has been achieved in Western Europe, with a con- tinuously decreasing number of blast furnaces and BOF converters.

It is possible to produce up to 6 million tonnes of top quality fiat products with

(1) two large blast furnaces, (2) one 3-converter BOF shop with hot metal pretreatment, (3) a multifunctional secondary metallurgy installation, (4) two classical slab casters, and (5) one hot strip mill.

In view of this high productivity, there is no doubt that the tendency to concentrate the production in the best per- forming integrated mills will continue during the coming years. As these mills have to receive very large orders and as the latter represent only a limited portion of the total steel consumption, the number of these steelworks will be limited in the future.

542--VOLUME 27B, AUGUST 1996 METALLURGICAL AND MATERIALS TRANSACTIONS B

Coal injection capacity (106Vyear) 12

10

8

6

4

2

0

=11

.., ill ,i I 1982 1984 1986 1988 1990 1992

Year Fig. 3--PCI capacity in Western Europe.

(b) As far as the cost of raw materials in integrated steelworks is concerned, the injection of important amounts of pulverized coal has allowed a decrease in the operating costs of the blast furnace by substituting coal for expensive coke. (A gain of 30 to 40 U.S. dollars per tonne of injected coal can be estimated.)

Figure 3 shows the rapidly increasing pulverized coal injection (PCI) capacity in Western Europe. Table I indi- cates that in four leading European steelworks, about 200 kg/tHM have been injected, which allowed the coke rate to be decreased below 300 kg/tHM.[2} This PCI level is now a target for all large blast furnaces.

(c) The phasing out of obsolete coking facilities, which is the result of PCI, is obviously an environmentally friendly operation. For the remaining coke plants, efficient methods for decreasing both air and water pollu- tion have been developed, but efforts must continue in order to further reduce the emission of pollutants.

The modern blast furnace requires a well-prepared bur- den; as classified lump ores of suitable quality are only available in limited amounts, agglomerated ore fines--pellets or sinter have to be charged. The advantage of the pelletizing process is that it can agglomerate very fine con- centrates and, if natural gas is used as a fuel, it entails a low emission of pollutants.

Sintering does not require hydrocarbons but uses coke breeze as a fuel; moreover, it accepts an appreciable amount of recycled materials. For these reasons, the large majority of European steel plants use the sintering process, where present developments aim at the reduction of SOx and NOx emissions.

Minimizing plant waste (e.g., by in-works recycling) and valorizing coproducts (e.g., by the use of slag in agriculture or civil engineering) are other important ecological objectives.

(d) Finally, the integrated steelmaker must deliver to his customer a quality product with superior properties. These are obtained with the help of a multi functional secondary refining installation and with perfectly con-

trolled continuous casters. Rolling and annealing operations must guarantee tight geometrical tolerances, a low scatter of the mechanical properties, and an appropriate surface quality. Subsequent coating operations ensure an excellent corrosion resistance.

Numerous studies are presently carried out in order to come to a thorough understanding of the inter-relations between all these process steps and the properties of the steel products delivered to the customer.

In large integrated steelworks, the degression effect of mass production on costs is fully effective, and this allows us to bear the expenses induced by the ecological requirements. The quality is superior to that obtained in any other process route. Enhanced productivity, low cost raw materials, environmental friendliness, and improved product quality will help the large integrated steelworks to continue playing an important role during the coming years. On the contrary, the earnings of small integrated steel plants are generally not sufficient for allowing them to rebuild, in the future, production facilities incorporating the latest technological development in coke, iron, and BOF steelmaking.

2. Market mills Thanks to the development of innovative melting and

casting technologies during the 1970s and 1980s, numerous small mills have been built for producing light long products, at low cost, in selected market areas. They are generally based on the electric arc furnace and on billet casters.

For market mills, the main short-term objectives are

(a) the improvement of the raw material's quality, (b) the diversification of energy sources, (c) the reduction of process steps, and (d) the creation of new business lines.

(a) It is well known that the quality of the main raw material of market mills--i.e., scrap---has deteriorated during recent years. TM Through a concerted action between the scrap collector and the steelmaker, this problem must be better taken in hand. Scrap becomes more and more polluted by metallic tramp elements and or- ganic compounds; this requires improved cleaning and sorting of scrap, by physical and chemical treatments. If the scrap quality is insufficient for achieving the required steel properties, virgin iron has to be added to the metallic charge. This addition can be hot metal, cold pig iron, or direct reduced iron. The direct reduction processes which today are in commercial use--i.e., MIDREX, HYL, and FIOR--produce about 20 million tormes Direct Reduced Iron (DRI) per annum, which is a rather small amount compared to the roughly 200 million tonnes of steel produced in 1993 by the EAF in the world.

(b) The second objective of market mills is the flexibility in energy sources. When electrical energy is expensive, its combination with fossil fuels, postcombustion, and scrap preheating is recommended. A power consumption of less than 300 kWh/t is expected with modem EAF furnaces (Figure 4). Similarly, a suggestion has been made to combine the features of the EOF furnace--scrap preheating, oxygen and coal injection, postcombustion--with electric en-

METALLURGICAL AND MATERIALS TRANSACTIONS B VOLUME 27B, AUGUST 199&-543

Table I. O p e r a t i o n Resul ts of Blast Furnaces with High Coal In jec t ion Rates

British Steel Hoogovens Sollac Thyssen

Blast furnace Scunthorpe Queen Victoria

Hearth diameter, m 9.0 11.0 Period 11.1 to 15.2.92 December '92 Output, t/24 h 3500 5858 Fuel consumption

Coke (dry), kg/t HM 294 272 Coal, kg/t HM 202 (granular coal) 212 Total, kg/t HM 496 484 Blast temperature, ~ 1124 1183 O: content in the blast, pct 29 26.6

IJ muiden 6 Dunkerque 4 Schwelgern 1

14.0 13.6 14.5 to 14.6.92 October '92 8726 9102

287 297.3 194 197.4 481 494.7 1189 1233 23.22 24.4

�9 g Fusion

Fig. 4--EAF of ProfilARBED Esch-Schifflange.

Low thickness beam blank

~ ! 4 0 0 "Standard" beam blank

H Beam blank for 1000 mm wide flange beam

Fig. 5--Different types of beam blanks.

ergy, in order to achieve a very low cost production technology. 14~

(c) A decisive step forward for market mills is the reduction o f the number o f process steps, when producing heavy long products. Casting beam blanks or near net shape beam blanks (Figure 5) instead of ingots or blooms enables significant shortening of the production line. The Differdange Steelworks of ProfilARBED, which produces wide flange beams with a web height up to 1000 mm and thicknesses up to 60 mm, will abandon this year the BF/BOF route and commission a 135 t DC-EAF furnace; at the same time, it will switch from the ingot route to the new beam blank technology. Fig- ure 6 shows that the layout of the wide flange beam mill will be simplified thanks to the elimination of the universal roughing mill and of the crop shear.tSl Com- pared to ingot or bloom rolling, the use of beam blanks

Universal J finishing ~ -~'

Universal intermediate mill Edger

~ Universal roughing mill Edger

Crop C.C.- beam ~ . r shear

blank ~ ~

down

Fig. 6----ProfilARBED Differdange Grey mill.

(d)

provides decisive advantages such as lower energy consumption, better yield, lower roll consumption, etc. Market mills do not intend to remain confined to long products and they look for new business lines, i.e., the production of thin flat products. In the same manner as billet casters did for long products, thin slab casting with integrated rolling has allowed minimills to enter the fiat product market, thanks to the competitive investment and operational costs of this solution in com- parison with classical slab casters and large hot strip mills. Producing liquid steel for fiat products in an electric arc furnace requires a precise metallurgical control aiming at low carbon and nitrogen contents at tapping�9 Thin slab casting also relies on an elaborate ladle metallurgy. The casting precautions which it requires, i.e., protection against reoxidation, quality of the casting powder, mold level control, etc., are as stringent as for classical slab casters.tr] Due to the rapid solidification, the segregation is reduced and this has a favorable effect on steel properties. The surface quality remains the main concern for thin slab casting and, in addition to factors such as casting powder properties and mold ge- ometry, a particular attention must be given to the scale formation and to its removal.

Thin slab casting is progressing rapidly and there is no doubt that further technological and metallurgical improvements will be realized in the near future, thanks

544 VOLUME 27B, AUGUST 1996 METALLURGICAL AND MATERIALS TRANSACTIONS B

Table II. Thin Slab Casters in Operation and under Construction (early 1994)

Company Country Builder Year

Nucor, Crawfordsville US SMS 1989 to 1994 Nucor, Hickman US SMS 1992 to 1994 Arvedi, Cremona Italy MDH 1992 Avesta, Avesta Sweden VAI 1988 Terni, Italy Italy SMS [993 Hylsa, Monterrey Mexico SMS 1994 Hanbo Steel, Pusan Korea SMS 1995 Armco, Mansfield US VAI 1995 Gallatin Steel, Warsaw US SMS 1995 Geneva Steel, Proro US SMS 1995

to the increasing number of machines in operation or under construction (Table II).

Due to their great flexibility in raw materials, in energy sources and in operations, market mills will continue to replace small-sized integrated mills. The extent of this phenomenon will, however, depend on the price, the availability, and the quality of scrap.

B. Medium-Term Evolution of the Production Routes

Section A has described the short-term actions which should now be taken by the different steel producers. But what next? Which technologies must be developed to keep the industry competitive and the companies successful at the beginning of the next century?

1. Ironmaking It is well known that ore preparation and cokemaking are

very capital intensive and that they create most of the environmental problems which the industry has to face. The dream of all steel producers is therefore to develop a tech- nique allowing coal and ore to be directly transformed into liquid metal.

Until now, many alternative ironmaMng processes have been proposed, but only the COREX process, which uses lump ore, pellets, or sinter, as well as lumpy coal as raw materials, has been operating successfully for several years at a scale of 300,000 t/year; a second installation, with an expected capacity of 700,000 t/year, is under construction.

Nevertheless, many specialists consider this approach as a first generation process which, because of its high degree of prereduction, prior to smelting, will have a significantly higher fuel consumption and gas export than the blast furnace. Its economic viability depends very much on the possibility of valorizing the large amount of clean, but relatively lean, top gas.

The other smelting reduction processes presently under development throughout the world use ore fines and coal fines as feedstock in order to avoid as well the coking operation as the agglomeration of iron ores. They generally consist of two superposed reactors: a prereduction vessel and a smelting vessel. As an example, Figure 7 shows the cyclone converter furnace (CCF), where prereduced ore with a prereduction rate of 20 to 25 pct is fed into the smelting vessel where a low postcombustion rate is per- formed; this vessel can be operated like a well-known K(M)S converter. Its off-gases travel through the cyclone and react with tangentially injected ore and coal and lead

Coal Off-gas

i

oxygen ~

on Ore )xygen

Hot Metal

l Slag

Fig. 7--Cyclone converter furnace.

finally to an excellent gas utilization (postcombustion ratio: 70 to 80 pct).Fl

Table III shows that none of these processes has today outpassed the pilot and demonstration stage tSj in spite of the considerable amount of research funds already invested (e.g., 140 million U.S. dollars for HISMELT[g]).

In view of the risks and costs inherent to these developments, it is questionable whether DIOS, HISMELT, etc. will reach industrial maturity during the present century. It is therefore wise not to condemn the blast furnace too quickly and, meanwhile, to continue its improvement.

Investigations are presently pursued to further decrease the coke rate, while at the same time increasing the productivity of the blast furnace. A process which has been proposed by CRM for this purpose (Figure 8) consists of the combination of a high coal injection rate (250 kg/t), the utilization of cold blast with very high oxygen contents (60 to 98 pct) and the reinjection of the top gas--after decar- bonatation below 5 pct CO2 and reheating up to 900 ~ to 950 ~ the bosh of the blast furnace.t~o] Such a practice would allow the attainment of very low coke rates and would minimize CO2 emissions. The blast furnace installations would be simplified and thus investment and main- tenance costs would be reduced. The nitrogen-free blast furnace could double the productivity which is obtained when the conventional coal injection and oxygen enrich- ment are applied. The first phase of this project, consisting of the injection of more than 250 kg pulverized coal per tonne hot metal, will start in the near future on a large blast furnace.

Even if PCI can be boosted to very high rates, the blast furnace still needs coke, even if it is a small amount. Figure

METALLURGICAL AND MATERIALS TRANSACTIONS B VOLUME 27B, AUGUST t996~545

Table III. S ta te of Development of Smelting Reduction Processes

Process

COREX

Company

Iscor/VAI

Development State

in operation

HISMELT (high intensity SMELTing) DIOS (direct iron ore smelting) AISI/DOE project CCF CIRCOFER/JUPITER

CRA Japan Iron and Steel Federation American Iron and Steel Institute Hoogovens/Ilva Lurgi/Usinor-Sacilor

demonstration plant 100,000 t/y, 1993 demonstration plant 150,000 t/y, 1993 pilot stage pilot stage pilot stage

DECARBONATION I

IREHEATERI ,~

CO2

T Coal 250 Kg

Fig. 8--Nitrogen-free blast furnace.

Cold blast 9 9 % 0 2

9 shows the coke production capacity in different regions of the world, estimated from the age of coke ovens, t''] It is foreseen that the current capacity will be reduced by half in 2010; in order to avoid a coke shortage, new cokemaking plants will have to be built in the future. The question is how these new batteries can be made environmentally compatible? The Jumbo coking reactor, the nonrecovery oven, and the formed coke process are candidates for meeting these requirements.

2. Steelmaking The improved preparation of obsolete scrap, the combi-

nation of electric and other energies in the EAF, the use of DRI or hot metal together with scrap, etc. will lead to the development of new melting technologies, most of which have already been envisaged in the past but which have not yet reached industrial maturity.V21

In particular, mixing either DRI with high carbon and gangue contents or hot metal with scrap may necessitate an important modification of the electric arc furnace, to ac- commodate slag foaming and high off-gas volumes (Figure 10).

In order to improve the internal and the surface quality of steels made from recycled scrap, new research efforts should be undertaken in view of the elimination of Cu, Sn, Sb, etc. from the liquid steel. In the field of continuous casting, innovative solutions are presently put forward in order to further simplify thin slab casters followed by in- line hot rolling. The final development stage in this respect is thin strip casting with or without in-line rolling, as it drastically reduces the number of process steps needed for obtaining thin flat products. The main question concerns

Cokemaking capacity (106 t/y) (coke oven life : < 35 years)

100

80 ~ ~ ~Asia

\ , 60 ~ E ~ �9

r ca 20 - - ~ - " ' ~ , , , . ~ ~ ~

Other countries " ~ ' ~ ,.,.~,,~

] 990 2000 2010 2020 Year

Fig. 9--Prediction of change in cokemaking capacity in the Western World.

Scrap )reheater

PROCESS AUTOMATION

!ncIosure

arbon and oxygen njection

Jet and ~xy-carbon burners

Porous plug for stirring

Fig. 10~Modem EAr Technolog'y.

the surface quality of thin strip and the cost of repair of eventual surface defectsY 3]

Table IV lists the pilot lines for casting wide strip presently operated throughout the world. A first commercial installation for producing large stainless steel coils might be ordered in the near future. Casting carbon steels by this process, however, is still far from being an industrial process.

3. Product development It is often said that a great number of steels which are

produced today did not exist 5 years ago. In view of the

546--VOLUME 27B, AUGUST 1996 METALLURGICAL AND MATERIALS TRANSACTIONS B

Table IV. Wide Thin Strip Casting Plants

Casting Speed Companies (~min) Coil Weight (t) Thickness (ram) Width (ram)

Nippon Steel + Mitsubishi HI Usinor-Sacilor + Thyssen Allegheny-Ludlum + VAI Krupp-VDEM + Nippon Metal Terni

20 to 90 l0 1.5 to 5.0 1220 45 15 3 1300 - - 10 to 20 1 to 3 1220 40 3 1.5 to 4.5 1000

max/100 20 2 to 7 800

aggressiveness of competing materials, the steel industry must continue to devote intense efforts to the development of new products with innovative characteristics and higher added value. Structural steels with a higher Young's mod- ulus, strip with a thinner gage, and dry coated products with improved corrosion resistance are examples of such new products. The latter must lead to an easy processing at the end user and, for this reason, the customer will be increas- ingly involved in their development.

It is obvious that for meeting these new requirements, appropriate technologies have to be conceived and brought to industrial maturity. For the efficiency of the primary and finishing operations, new sensors, automation, robotics, computer control, and information systems are essential.

II. NEW TECHNOLOGIES REQUIRE LARGE R&D EFFORTS

The new technologies, which will be developed during the coming years for iron- and steelmaking, for near net shape casting and direct rolling, and for finishing and coating, are indispensable for maintaining a dynamic and profitable steel industry.

There is no doubt that the aforementioned short- and medium-term objectives require important investments in research. Each individual steel company must therefore have an appropriate research strategy and manage its research funds in a productive and cost-efficient way.

In particular, it is essential to evaluate by which of the following methods a given task can be best fulfilled:

(1) by the company's research forces alone; (2) by partially or totally subcontracting a task to a third

party, e.g., a research center, a university, an equipment manufacturer; or

(3) by collaborating with one or several other steelmaking companies.

In 1990, the European steel companies, members of IISI, spent 0.80 pct of their sales revenue for R&D on processes and products; this corresponds to about 5 U.S. dollars per tonne of crude steel. These figures show that steel companies have only limited funds at their disposal for developing future technologies and for carrying out in-depth investigations on the fundamental aspects of present and future processes. A remedy to this situation is a collaboration between different producers, in order to make sufficient money available for important projects in technological in- novation.

Already today, two or more steel companies often join their efforts for tackling a given problem and this ad hoc cooperation ceases when the project has been finalized. It appears however that the joint effort is more effective when

the companies rely on a permanent research stntcture with specialized research teams. This role has been played in the Benelux countries by CRM during the last 46 years. Its characteristical features are given in Appendix I, and in Sections A through D, four of its ongoing research projects in the fields of ironmaking, steelmaking, finishing, and product development are described.

A. Partial Recirculation of Waste Gas in Sinter Plants

CRM has at its disposal a large pilot hall for executing research projects in the fields of iron ore preparation, cokemaking, and hot metal production. The test facilities com- prise a 450 kg pilot coke oven, a 3t/day experimental blast furnace, and an experimental sintering pot with an ore capacity of 80 kg.

Sinter plants produce large amounts of waste gas con- taining pollutants such as NOx and SO x which must be reduced due to the more stringent environmental regulations. In the near future, de-NO, and de-SO x treatments will be required which are costly and require large areas near the sinter plant for installing the appropriate equipment.

A possibility for lowering the related costs is to recycle a portion of the exhaust gases in order to reduce the off- gas volume to be treated. In this approach, the recirculated gas has to be mixed with fresh air in order to provide the oxygen required by the coke breeze combustion (Figure ll) .

Additional beneficial effects of this recirculation might be that part of the NOx is destroyed in the flame front and that a percentage of the SOx is fixed in the sinter cake. Furthermore, the CO of the recirculated exhaust gas will be burnt in the flame front, and this will lead to a decrease in coke breeze consumption which in turn will reduce the NOx and SO, emissions.

With the support of its affiliated companies, CRM has undertaken the following research program.

(a) A new pilot plant has been built for simulating the exhaust gas recirculation in industrial conditions. A "syn- thetic gas" with well-defined compositions, corre- sponding to increasing recirculation rates, is pulled down through the mix in the sinter pot (Figure 12).

(b) The highest recirculation rate compatible with a good sinter quality and a normal productivity is determined.

(c) The behavior of recirculated CO, NO c, and SOx volumes is characterized.

(d) The results of these tests will be further verified on an industrial sinter strand with gas recirculation.

B. Thin Slab Casting and Ferritic Rolling

It has already been said that thin slab casting with direct rolling is a very cost-effective new technology to produce

METALLURGICAL AND MATERIALS TRANSACTIONS B VOLUME 27B, AUGUST 1996--547

CONVENTIONAL PROCESS _+1200m 3N air

l Figures

L--3 r - - q .

Sinter ~ 5 strand I I I JJl. I I I

V

_+ 1400 m 3 N off-gas to be treated

Fig. 11---Gas stream balances for conventional and new sintering processes.

NEW PROCESS _+ 400 m 3 N air

per tonne of sinter ~, _+ 750 m3N ~ recirculated gas

Sinter ~ / V ~ / ~ / ~ / ~ / ~ ~, strand I I , ~ I l e ~

_+ 600 m 3 N off-gas to be treated

CO2

Electric h e a t e r ~ I i

SO 2

I Gas mixer I

Exhaust gas I Sinter [

Air

02

H 20 vapor

NOx

Fig. 12--View of CRM's equipment for exhaust gas recycling simulation.

hot- and cold-rolled steel sheets, especially in combination with an electric arc furnace; the same conclusion applies to hot rolling of beams from beam blanks.

If this new approach is well suited to produce ordinary steel grades, a process optimization is required when con- sidering high grade steels for which special properties have to be ensured, e.g.,

(a) deep drawability or high resistance for cold-rolled sheets; and

(b) high toughness for beams and sections.

In terms of process/product relationships, the following basic metallurgical aspects must be investigated:

(a) the increased cooling rate at the solidification stage which may influence the precipitation mechanisms for alloying elements;

w =150-180mm

Induction furnace

(25 kg-vacuum)

Fig. 13--Melting and casting furnace.

(b) the reduced through-thickness reduction which modi- fies the refinement of the microstructure; and

(c) the increased nitrogen and tramp element contents of the liquid steel from which changes in mechanical properties of the end product may be anticipated.

CRM has developed appropriate laboratory facilities in- tended to obtain basic knowledge in these different fields. The experimental line which has been built for this purpose is based on a vacuum remelting furnace able to supply, within 90 seconds, a 20 kg partially solidified steel sample having a thickness of 40 mm (Figure 13). As shown in Figure 14, this melting facility is located just in front of two successive reversible four-high mills, which are used, respectively, as roughing and finishing mills, with an exit speed up to 1 m/s.

An equalizing or reheating induction furnace is built in line for heat treating prior to rolling; this is of prime im- portance in terms of microprecipitation. For cooling on the runout table, a water spray accelerated cooling system is installed at the exit of the line. In the case of fiat products, coiling of the hot strip can be simulated by furnace cooling of the specimen. Lubricants can be applied in the finishing

548---VOLUME 27B, AUGUST 1996 METALLURGICAL AND MATERIALS TRANSACTIONS B

Induction heater

Gas F:~ ~. cutting y U T~

OCs

Rolling Rolling stand 1 C~il stand 2

Cooling section

H20

Coiling section

I I

I

Fig. 1 4 - - ~ R M ' s experimental direct hot-rolling line.

65 4 3 2 1

~ -- i

~ 7 fGALVANIZ INGL~ I|

Fig. 1 5 - - C R M ' s continuous heat treating and coating pilot line.

mill by spraying prefixed quantities of lubricants either on backup or on work rolls; currently used lubricants are min- eral oils, esthers, or fatty acids used as pure oil or emulsion.

All processing parameters from the caster, rolling mills, and cooling section are collected by means of a data-log- ging system.

As an example, this powerful experimental line is used for studying problems related to the development of the so- called "ferritic hot rolling" of low carbon steels from conventional concast slabs or from thin slabs. Reheating to a low temperature around 1050 ~ combined with a final hot roiling in the ferritic domain produces a very soft and non- aging hot band, very well suited for subsequent cold rolling and continuous annealing. This new hot-rolling practice results in significant cost reductions in terms of energy saving in the slab reheating furnace, as well as in terms of ex- tended lifetime of the work rolls in the finishing mill.

C. Continuous Heat Treatment and Coating

Annealing and coating operations are of prime impor- tance for the quality of the products delivered to the customers. Developments are presently pursued at CRM for working out products with attractive user properties as well as technologies allowing these products to be manufactured in a reliable way and at a reasonable cost.

The large continuous heat treatment and coating pilot line operated by CRM represents the ideal tool for experiment- ing with new solutions prior to their industrial application. This line comprises annealing and hot dip coating facilities allowing strip between 0.1 and 1.5 mm in thickness, with a maximum width of 300 ram, to be processed at reasonable

speed (70 rn/min maximum). Two line configurations are possible, as described in the following (Figure 15).

In the first configuration, the strip is heated first in the direct flame (1) and afterward in the radiant tube (2) furnaces; it is then cooled down to the ambient or an intermediate temperature in section (3) and can be overaged in the furnace (4) and finally cooled in section (5). It is possible to perform surface treatment in the tank (6). The second configuration corresponds to the case where hot dip galvanizing is realized after annealing; the galvanizing section (7) can be provided with facilities also for galvannealing.

The objectives include improvements in products and techniques as well as the development of totally new processes. Given its versatility and very wide operating ranges, this line has gained the support of other research institutes so that, besides the proper research program of CRM, collaborative developments are being conducted within the frame of multinational projects, some of which are listed in Table V.

The improved galvannealing process described under point I of this table will, in the near future, be tested on the industrial line of Segal (Lirge, Belgium).

D. A New Product: Elofoil

CRM, together with its affiliated companies Cockerill Sambre, Hoogovens, and Arbed/Sidmar, has developed, on a preindustrial stage, the Elofoil process for producing a new iron material which is as thin as foil: its thickness ranges from 10 to 80/xm.

Elofoil is made by electrodeposition of iron from an electrolyte, a highly concentrated solution of iron salts. Elec- tricity is used to deposit the iron from this salt solution on a rotating metal drum. The layer of iron grows thicker as more current is applied, until the desired thickness of the Elofoil is reached and the foil is peeled from the drum, rinsed, dryed, and coiled (Figure 16).

To replenish the iron that is removed from the electrolyte, clean and pure scrap iron is dissolved in mild acid in a regenerator. Impurities are filtered out and the electrolyte is recirculated to the forming cell. The use of clean scrap as the raw material makes the production of Elofoil a high quality form of recycling of materials.

The core of the Elofoil process is the patented high tur- bulence, low pressure (HTLP) anode, which enables the electroforming process to take place at high intensity in a small volume. This anode requires little pumping energy and has a high electrical efficiency (Figure 17). The Elofoil


Table V. Research Projects Carried Out on CRM's Pilot Line

Research Project/Partners Objectives

1. Improved galvannealing Segal Cockerill Sambre Hoogovens Sidmar

2. New wiping technology British Steel CSM Ilva Hoogovens

3. Ultra short annealing cycle British Steel Hoogovens EA Technology

4. Improved strip guiding IRSID

5. Hot gas heating and supporting Thyssen BFI

I. Getting more accurate control of the galvannealing process by means of new sensors

2. Approaching the "square" thermal cycle for reduced powdering thanks to (a) very fast and easy controllable reheating (HF induction) (b) very fast cooling (misting jets)

1. Decreasing scatter in coating thickness (a) lower sensitivity to variations in strip position (b) damping of strip instabilities (c) easy and reliable operation

2. Reaching higher line speed 3. Reducing environmental impact

1. Developing methods for achieving ultrahigh heating and cooling rates 2. Investigating annealing effects associated with the use of ultrarapid heating and

cooling rates 3. Evaluating potential benefits

1. Preventing folds for critical sizes of mild steel strips processed at high speed in continuous annealing lines

2. Ensuring proper guiding of the strip by new actuators

1. Working out an efficient heating system for continuous annealing lines 2. Preventing contact with supporting devices during strip transport and treatment

Electroformer

Re ener or Tank

J I I.al i i 1 , / o

Fig. 16--Continuous production of foil by electroforming.

process operates at a high temperature and a high current density, thus improving the efficiency and output. All materials used are highly resistant to the solution o f acid and salts at operating temperatures. The feasibility o f this process was demonstrated in 1992 and 1993 on a semi-industrial pilot line having a capacity of 50 kg/h; 300-ram-wide coils up to one tonne were produced in thicknesses ranging from 10 to 80/zm. The application possibilities o f Elofoil can be found in two main areas: packaging and electro- magnetic shielding.

III . O U T L O O K

At the beginning of this lecture, it was pointed out that, presently, customer requirements and environmental regulations confront the steel industry with major challenges, which can only be met if new technologies are developed,

Electrolyte flow

Fig. 17--Principle of the HTLP Anode.

thus allowing drastic changes of the production lines to be carried out.

Certain near net shape casting technologies have achieved, today, industrial maturity and they give the management o f steel companies real options conceming size, geographical location, layout, and organization o f future steel plants. Other technologies---e.g., smelting reduction-- have not yet reached a sufficient development stage for con- stituting real alternatives to the existing processes.

Intense research efforts are required to bring these new processes from the pilot stage to industrial application. At the same time, the steel companies must continue to devote their attention to the optimization and understanding of the

550~VOLUME 27B, AUGUST 1996 METALLURGICAL AND MATERIALS TRANSACTIONS B

Table VI. European Pilot and Demonstration P r o j e c t s

Research Project Industrial Partners

High PCI in blast furnaces CCF Circofer Quenched and self-tempered beams Head-hardened rails Optimization of the galvannealing process On-line roughness measurement of cold-rolled steel sheets Elofoil Easy opening steel cans

British Steel, Hoogovens, Ilva Hoogovens, Ilva Usinor-Sacilor, Thyssen ARBED Group, British Steel ARBED Group, British Steel Cockerill Sambre, Hoogovens, Sidmar Sidmar, Cockerill Sambre, British Steel Cockerill Sambre, Hoogovens, Sidmar British Steel, Hoogovens, Rasselstein

present process routes. There appears to be a real discrep- ancy between the research funds which are necessary for these undertakings and the resources which can be made available. It is now generally accepted that a solution can only be found in the cooperation between different steel companies.

Table VI lists examples of common R&D projects, jointly undertaken by European steel companies. These projects have all been sponsored by the Pilot and Demonstra- tion Program of the European Coal and Steel Community, whose funds stem from a levy raised from the steel industry (Appendix II).

In 1993, the ECSC research budget amounted to 34 million ECU, which represents 0.25 ECU per tonne of crude steel, i.e., less than 0.10 pet of the turnover of the companies. CRM, the common research center of the Benelux steel companies, has participated in many of these projects.

The question which is debated presently concerns the future form of joint steel research in the European Union. Similar discussions are also underway in Japan and in the United States; in 1991, Bill Dennis devoted his Howe Me- morial Lecture to this subject.t~41 The ECSC treaty comes to an end in 2002 and a new frame for joint European research now has to be established.

The experience gained over 30 years of this collaborative research has demonstrated that, in addition to serving as a stimulus to R&D and encouraging technological progress, the ECSC approach to cooperation has offered additional benefits which include the following:

(a) an opportunity to combine the different skills and ex- pertise as well as the different approaches to problem solving that exist in the community;

(b) enhancing the contacts between experts in the steel industry; the ECSC Executive Committees have developed into a permanent valuable network of international contacts between scientists and technologists within the Community's steel sector (this has proved to be a useful stimulus to broader cooperation and inter- action on scientific and technical matters far beyond the ECSC research work; and

(c) reducing the duplication of effort and promoting a better coordination of steel research in the Community while also permitting large, costly projects to be undertaken that individual organizations could not carry out alone.

It is important that these advantages are preserved up to 2002 and beyond. The European Steel Industry is presently

giving this problem due consideration in discussing more particularly the following aspects:

(a) the mechanism and level of funding of joint research by the Steel Industry of Western Europe;

(b) the possibilities of public funding (in accordance with the GATT and MSA agreements);

(c) the management structure of the future joint research program; and

(d) the role which can be played by the existing European institutes for collaborative research.

A decision concerning the future collaborative European research on steel technology will be made in the near future.

I would like to end this lecture by quoting B. Moffat, Chairman of British Steel, who at the last IISI Annual Meeting said:tW51 "Managing the technological change is an important part of the steel industry's tradition. The chal- lenge facing the management of any industry is how to adapt to a changing environment. The successful companies will be those who seek out and embrace change, recogniz- ing the opportunities presented by changing markets, changing requirements and changing technology. Those who ignore or attempt to resist change will inevitably wither away."

APPENDIX I Collaborative research at CRM

CRM is a unique example of a Joint Research Institute operated by several steel companies for developing new technologies and for acquiring knowledge on innovative processes.

CRM was founded in 1948 as a nonprofit organization with the objective of carrying out research for improving the metallurgical fabrication processes and the quality of the metallurgical products. The active members in the field of iron and steelmaking are as follows:

ProfilARBED Luxemburg Cockerill Sambre Belgium Hoogovens Groep The Netherlands Forges de Clabecq Belgium Sidmar Belgium Usines G. Bo~l Belgium

The total raw steel production of these six companies amounted to about 18 million metric tonnes in 1993, while


Million ECU 80

60

40

2O f j -v--- 0

Hq 1970 1975 1980 1985 1990 1995

Year

Fig. I I a - - E C S C R&D budget.

their individual productions ranged between 0.8 and 5.9 million tonnes. For generating a critical mass of research funds, in order to execute sizable research projects, the Be- nelux companies decided to collaborate.

The role of a joint research institute has to be well defined in order to avoid overlapping with the research efforts made in each individual affiliated company. CRM's mission is as follows:

(a) to develop, on a medium-term basis, new technologies for the reduction of iron ore, the refining of liquid metal, and the casting, shaping, and finishing of steel; and

(b) to acquire basic knowledge aiming at a better understanding of the different process steps, on the relation between process variables and steel properties.

The short-term improvements on processes are normally excluded from CRM's activities; they are executed by the affiliated companies themselves.

CRM also avoids getting involved in the relations between steel customers and individual producers. The eight research departments of CRM are as follows:

Process Technology

Ironmaking Steelmaking and refractories Rolling and finishing Measurement and control

Metal Science

Physical metallurgy Metal surface Metal properties

Environment

The joint research program of these departments is established on a 2-year basis in a close collaboration between CRM's research specialists and their counterparts in the affiliated companies. The guidelines and priorities of the program are defined by the Iron and Steel Committee of ClaM, which comprises the Executive Vice-Presidents Technology

of the affiliated companies and their Research Directors. Every 3 months, CRM presents to this Committee a progress report on the ongoing program.

The personnel of CRM responsible for executing this program presently include 200 persons, among whom 80 hold a university degree or equivalent. The total surface of CRM's laboratories and pilot installations is 15,600 m e.

In 1993, the total budget of CRM amounted to 24.5 million U.S. dollars (1 dollar = 35 BEF); 40 pct of CRM's income is from direct contributions from the member companies for the aforementioned joint research program. The Steel Industry pays a fixed contribution of 0.5 U.S. dollars/t per tonne of liquid steel to CRM; 20 pct of this amount is from contributions in kind, i.e., expenses in the steelworks for executing applied research based on CRM's laboratory and pilot plant results.

Specialists of the affiliated companies participate in the transfer of the laboratory results to pilot and demonstration installations in the steelworks.

Twenty percent of CRM's income is contributed by the Belgian Public Authorities who have encouraged industrial research since 1948. The European Community raises a levy from the Steel Industry of the European Union based on its annual turnover. Part of this levy is used to fund collaborative European Steel Research (Appendix II) and 18 pct of CRM's income stems from this source. The remaining part of CRM's income results from private research contracts with affiliated companies or with companies located outside Benelux. CRM also sells engineering and can give licenses of the processes it develops to nonmember companies.

APPENDIX II ECSC research collaboration

A major program of international collaboration on steel research has existed in Western Europe since 1955, being stimulated and financed under the provisions of the Treaty that established the European Coal and Steel Community. The basis of this early initiative in transnational collaboration in research was the belief that science and technology would make a vital contribution to the growth and future competitiveness of the steel industry in Western Europe.

The evolution of the funds devoted to ECSC steel research projects, in recent years, is shown in Figure IIa; about one-third of the budget is devoted to Pilot and Dem- onstration Projects, whose aim is to demonstrate the technical and economical relevance of research work carried out previously and to help to bring the experience acquired into industrial applications.

The European Commission has the responsibility for the implementation of the program and for its overall management and organization covering both technical and financial matters. In this respect, the four main tasks that have to be undertaken cover (a) defining a research policy, (b) for- mulating an annual research program, (c) managing and coordinating the research in progress, and (d) disseminating the research results.

A. Research Policy

The policy for research, which is formulated in consul- tation with industry, is based upon the projected develop-

552--VOLUME 27B. AUGUST 1996 METALLURGICAL AND MATERIALS TRANSACTIONS B

ment of the steel sector and its future technological needs. Particular emphasis is being placed on the contribution technology must make to the modernization and restructur- ing of production facilities as well as to the promotion of market opportunities for steel products in the face of severe international competition. To ensure that the program re- sponds to the changing scientific, technical and economic requirements of the industry, guidelines for this collaborative effort are periodically published in which priority sub- jects for research are identified.

B. Annual Research Program

The annual research program is based upon proposals received every year by the Commission from industry and research organizations. In the assessment and selection of the proposals, the Commission consults different committees in which the steel industry and the national govern- ments of the Member States are represented. When completed, the Commission makes the final decision on the program to be funded and, in recent years, it has been possible to support annually more than 100 proposals out of a total of over 200 received.

C. Project Management

Each research project is monitored by a series of technical committees (Executive Committees) which meet twice a year to examine the progress and final reports and to discuss the future direction of the work. These committees cover the research being carried out in different technical areas and are composed of experts from industry, research establishments, and universities in the Community along with representatives of the beneficiaries.

D. Dissemination of Research Results

While the Executive Committees referred to in Section D play a large part in the diffusion of information, a small percentage of the annual budget is set aside for the following:

(a) printing and publication of the final reports on each research contract;

(b) drafting and publication of an annual report based upon the activities of each of the Executive Committees; and

(c) organization of symposia, seminars, and international conferences where the results of ECSC work in a given area are presented and discussed.

In all these aspects of program organization and management, close cooperation between the Commission and the steel industry has proved to be an essential element in the successful implementation and execution of this collaborative research effort.

ACKNOWLEDGMENTS

The author expresses his sincere thanks to his colleagues: Mr. M. Economopoulos, Dr. A. Etienne Dr. V. Leroy, Mr. A. Poos, and Mr. S. Wilmotte for their important contributions to the present article.

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10. A. Poos: Proc. 6th Int. lron and Steel Congr., Nagoya, Japan, 1990. 11. A. Tomiura and I. Komaki: Proe. 27th Annual Meeting of IISl. Paris,

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