(SANITIZED)PRODUCTION OF OXYGEN-FREE COPPER FOR THE ELECTRICAL INDUSTRY IN YUGOSLAVIA(SANITIZED)

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80T00246A011300260001-7
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 54
• Document Creation Date: December 22, 2016
• Document Release Date: July 22, 2009
• Sequence Number: 1
• Publication Date: September 27, 1960
• Content Type: REPORT

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Translation from Serbo-Croatian.
Elektrotechnika, vol.8,No.1,1959,p.85-.93.
PRODUCTION OF OXYGEN-FREE COPPER FOR THE
ELECTRICAL INDUSTRY IN YUGOSLAVIA.
Dragoslav Janicijevic, Chief Metallurgist,
Fabrika Kablova Svetozarevo, Svetozarevo, Yugoslavia.
SUMMARY
During the past two decades, electric furnaces have
increasingly replaced conventional reverberatory
furnaces for copper melting. Two types of electric
furnaces are used, arc furnaces and low frequency
induction furnaces. The latter type, in conjunction
with a special casting process, under exclusion of air,
is used today to produce copper wire bars of superior
quality which is known on the world market as oxygen-
free copper of high conductivity.
A plant for production of this type of copper, the
third in the world, started operation in June 1955
at the Fabrika Kablova Svetozarevo. The present paper
briefly describes the quality of oxygen-free copper,
the history of the special process, and the production
methods and equipment used at the Fabrika Kablova.
Finally, some idea is given of actual operations and
product controls.
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INTRODUCTION..
Yugoslavia was known as a source of cathode copper of
good quality even before the construction of the Fabrika
Kablova "Mosa Pijade" at Svetozarevo and of the Copper and
Brass Mill at Sevojna. The installation of these two large
plants, in addition of the few older copper producers, has
meant a transformation in the copper industry of the country.
The copper processed in 1957 was 76.5% of the entire Yugo-
slavian copper output, 41.6% being passed through the cast-
ing shop and rolling' mill of Fabrika Kablova.
Despite this strong increase in capacity, which led to
a brilliant export trade, the Fabrika Kablova Svetozarevo
began by importing cathode copper, for the first time
making Yugoslavia an importer of copper.
Today, the Fabrika Kablova have established a good repu-
tation even beyond the borders of Yugoslavia, but little
is known of its production methods. The success of the
enterprise may be ascribed to the choice of producing
oxygen-free copper.
It has been customary in the past to produce wire bars
at the electrolytic refinery. When the Fabrika Hablova
Svetozarevo were planned, it was decided to depart from
conventional practices and to cast the wire bars right at
the wire and cable plant. Several melting and casting
methods were considered, such as stationary or rotary
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reverberatory furnaces, horizontal casting wheels, and
others. Finally, it was decided to use a process for pro-
duction of oxygen-free copper. Today, the Fabrika Kablova
Svetozarevo is the only plant in the world whose entire
production consists of oxygen-free copper. The plant has
now been in operation over two years (in 1959) and it has
been found that the choice of process and equipment was
entirely justified.
This paper is intended to acquaint the engineering
public in general with something new in metallurgy, with
a process that has been tested in our country for several
years.
WHAT IS OXYGEN-FREE COPPER?
Oxygen-free copper is a type of copper produced by a
patented process, and until recently it was manufactured
exclusively by the U. S. Metals Refining Company, Carteret,
New Jersey, a subsidiary of American Metal Climax, Inc.,
under the registered trademark "OFHC".
Oxygen-free copper is not deoxidized copper, i.e.,
copper from which the oxygen was removed by means of
phosphorus, lithium, or some other metallic of metalloid
reducing agent; it is a copper which has not been oxidized
during remelting, and therefore requires no oxygen removal.
Copper from which oxygen has been removed by some agent
is called deoxidized copper.
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Oxygen-free copper is produced In equipment which
maintains the molten metal protected from contact with
air throughout the entire process. The selected cathode
copper is converted directly into the desired cast shape
under strictly controlled conditions, thus avoiding con-
tamination of the pure electrolytic copper.
This type of production assures a very high quality
metal with a copper content ranging from 99.95% to 99.99%.
Since the impurities are kept very low - of the order
of about 0.01% - the metal has the characteristics of
pure copper. Some of the important properties of oxygen-
free copper are the following:
a) High Ductility. This metal has a remarkable capa-
city for undergoing successive drawings without inter-
mediate annealing. Ductility of oxygen-free copper Is
practically unchanged by cold deformation. Therefore, it
is particularly suitable for any type of deep drawing.
The occurrence of "ears" is unknown in this type of
copper.
b) High Electrical Conductivity. It is assumed that
the conductivity of copper is affected by the presence of
unoxidized impurities In solid solution. Oxygen-free
copper guarantees high conductivity because of Its high
purity and freedom from impurities.
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c) Immunity to Embritttlement. When heating oxygen-con-
taining copper to a relatively high temperature in a
hydrogen-containing reducing atmosphere, the oxide is de-
composed - under formation of water vapor - breaking
down the edges at the crystal boundaries and impairing
metal quality. Oxygen-free copper is immune to this type
of deterioration, and therefore is well suited to gas
welding, bright annealing, and other operations where
copper comes in contact with hot hydrogen. Thus, this
copper type is particularly suited for applications in
electronics for high-vacuum components because it does
not break or become brittle, as is the case with copper
containing oxygen.
d) Ability for Form Hard Adhesive Oxide Skins. This
is one feature of oxygen-free copper of particular ad-
vantage to the electronics industry. When this copper
type is heated above 800 C (1470 F), a hard adhesive
oxide skin is formed on the metal surface which permits
a permanent tight connection with glass and guarantees a
,permanent vacuum in electronic tubes. Copper containing
oxygen or phosphorus, even as little as .0005%, does
not have this property.
e) High Softening Point. Since the impurities are
present in solid solutions, oxygen-free copper softens
at a higher temperature than ordinary copper after cold
deformation. Elements in solid solution, even when pre-
sent in very small amounts, raise the softening tempera-
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ture. Therefore, oxygen-free copper is well suited for
apparatus and machinery working under difficult conditions
where the metal is subject of special stresses in addition
to a higher temperature.
f) Low Vapor Pressure at Very High Vacuum. There are
no gas occlusions in oxygen-free copper, a result achieved
by the high densities obtained with this casting process
(8.89 to 8.93 kg/dm3 In the as-cast condition). Further-
more, there are no impurities present that may have a low
vapor pressure at various temperatures under high vacuum.
This property is of particular importance for production
of high-emission tubes.
In addition to the above properties, oxygen-free copper
has other characteristics different from those of ordi-
nary or deoxidized copper, such as high Impact resistance,
creep resistance, excellent anode distribution during
plating (electrolytic coating), etc.
During World War II, oxygen-free copper was in great
demand and the metal was rationed. It was used for making
electronic tubes for radar equipment and thin-walled tubes
for aviation heat exchangers. In our country, oxygen-free
copper is used chiefly in the production of several types
of cables and conductors and to a smaller extent in the
electronics industry; from the beginning, it has shown its
superiority, both from the point of view of quality and
of processing and workability range of the metal.
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HI STORY.
Oxygen-free copper was little more than a metallurgical
curiosity until the Scomet Engineering Company started its
Summey induction furnace with two melting chambers, the
first and largest plant in the world, to begin commercial
production. Before that time, only small quantities of
dubious value and quality were obtained from laboratory
experiments.
The first attempts to obtain oxygen-free copper were
made as early as 1919 In the foundries of the Scovill
Manufacturing Company, Waterbury, Conn. However, this
company was not in a position to continue the very
promising work that had been started. Almost ten years
passed until means were found to continue with these
early experiments.
In 1928, an agreement was reached with the American
Metal Company, Ltd. (now known as American Metal Climax,
Inc.), on the basis of which facilities were made avail-
able at Carteret, N.J., for the production of oxygen-free
copper by its wholly-owned subsidiary, the U.S. Metals
Refining Company. The oxygen-free copper manufactured by
this company since 1931 has been sold under its sole
and exclusive "OFHC" trademark.
The complete success of this venture was jeopardized
at first by the frequent breakdowns of the refractory
lining in the Summey furnace inductors. Even then, high
conductivity oxygen-free copper was produced to satisfy
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the great demand, but a conventional reverberatory furn-
ace was used for the preliminary refining by the classi-
cal method, supplemented by passing the molten copper
through a charcoal-filled deoxidizing unit.
During World War II, the demand for oxygen-free copper
increased beyond the available productive capacity. For
this reason, and becuase of the many other advantages of
the process, a new production unit was erected at the
U.S. Metals Refining Company and started operations in
1942. This plant uses a Summey induction melting furnace
with oscillating movement and a protective atmosphere,
eliminating the reducing unit. The refractory material
used for the inductors in this furnace is now more care-
fully chosen and the inductors are more durable; many
other improvements have been made to the process, such as
moisture removal from the protective gas used, etc. This
furnace is still In operation today, producing 7-8 tons
per hour of "OFHC" copper in commercial shapes.
At the beginning, the metal was cast into vertical
molds and most oxygen-free copper still is produced in
this manner; however, continuous casting was furst applied
in 1942, initially with Welblund-Benard, or INCO, casting
machines and, after 1948, with Junghans-Rossi casting ma-
chines. In all instances, casting is conducted under a
protective atmosphere.
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The basic disadvantage of the Summey furnace was the
long time required for replacing an inductor (10-15 days),
and the relatively short inductor life (t1.-8 months), and
this led to the development of the Scomet and Ajax-Scomet
furnaces. One such furnace was installed at Pori, Finland,
by the Outokumpu Mining Company in 1939, which operated
the furnace and produced oxygen-free copper under license
by the Scomet process. These casting furnaces have a single
chamber serving for both melting and pouring, and casting
is done Into vertical water-cooled chill molds on a rotat-
ing wheel, using a reducing unit.
Towards the middle of 1952, negotiations were started
and at the end of that year (December 10, 1952), a contract
was signed with the Ajax Engineering Corporation of Tren-
ton, N.J. This contract enabled construction of the third
plant In the world to produce oxygen-free copper by the
Scomet process, at Svetozarevo, Yugoslavia. Construction
took about two years. The new plant differs from the two
above mentioned operations in that the casting shop at
Svetozarevo is more modern and highly automated, its
entire production being cast by Junghans-Rossi casting
machine. The basic shape cast here is the wire bar.
Figure 1 gives a general view of the casting platform.
BRIEF DESCRIPTION OF PROCESS.
Copper cathodes are produced by electrolytic refining,
the most perfect method of purifying the metal; because
of their shape, however, the cathodes have to be remelted
A`
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and cast into commercially desirable shapes. Before
electric furnaces were used, remelting was carried out
in reverberatory furnaces which make it impossible to
avoid contamination of the high purity copper cathodes,
and therefore a complete fire-refining process is required.
Today, according to American statistics, 80% of all pri-
mary copper produced is in the form of cathodes; 72% are
still remelted in reverberatory furnaces and about 8%
in electric furnaces, of which 3.2% are used for pro-
duction of oxygen-free copper in low frequency induction
furnaces, and about 4.8% are remelted in electric arc
furnaces.
The contamination of the high-purity cathode copper
Inevitably occurring in the reverberatory furnace called
attention to the advantages of electric furnaces. It was
found that economical remelting of the cathodes would
ordinarily have caused contamination unless-the small
amounts of sulphur and gases usually entrapped in the
charge are eliminated. This idea forms the basis for the
patented process of remelting cathode copper under a pro-
tective atmosphere, and for the production of oxygen-free
copper of high conductivity.
Figure 2 shows a schematic diagram explaining the
production of oxygen-free copper at the Fabrika Kablova cast-
ing shop: Electrolytically refined first-quality copper
cathodes (1), containing at least 99.96% Cu, and having
a fine-grain structure, hard and dense, without large
amounts of nodules, well washed, with sulfate removed
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as much as possible, with no carbon, pigments, or other
impurities of any kind, are charged continuously into the
melting furnace (3). The metal flows continuously from
this furnace through an electrically heated launder (4)
into the pouring furnace (5). From the pouring furnace,
the molten copper flows at a precisely determined tempera-
ture into the bottomless chill mold (7) in which the metal
solidifies Into the shape of the wire bar. Beneath the
chill mold, In a special chamber, ring-shaped sprayers
(8) are located which cool the wire bar to room tempera-
ture. From this chamber the water runs into the sewer and
the wire bar passes through a rubber wiping box to trans-
port rolls (9) which draw It 'down. at a constant speed to-
wards the saw. Cutting the wire bar into determined
lengths Is done automatically by a mechanism moving down-
wards with the wire bar, which consists basically of
clamps (10) holding It firmly, a rotary saw (11) which
moves horizonally, and a basket (12) for transfer to the
gravitation conveyor (13). In both furnaces the molten
metal Is covered with a layer of charcoal (2).
The protective gas is produced In a special group of
apparatus, starting with a "Galusha" gas producer (14)
from where it passes through a scrubber (15), a sulphur
remover (16), a gas converter (17) for complete com-
bustion of the producer gas, and a refrigerator (18) for
moisture removal; thence to another generator (19) of
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"drycolene", where the converdter gas is reduced in a re-
tort by red-hot charcoal. The reduced gas is filtered at
(20) and passes to the hood (6) above the chill mold and
Into the melting furnace, the heated launder, and the
pouring furnace, eliminating all possibility of contact
between molten metal and atmosphere.
MELTING AND CASTING EQUIPMENT AT THE FABRIKA KABLOVA SVETOZAREVO
A. The Melting Furnace consists of a hexagonal welded-
steel drum with openings at both ends, for cleaning the
furnace and charging charcoal, respectively. The cathode
charging door is located at the center of the drum's
upper end, slightly above the horizontal plane passing
through the horizontal axis of the drum. A pair of open-
ings is provided on each side of the lower half of the
drum for installation of the inductors. Figure 3 shows
the construction of this furnace.
At the front end of the furnace,.at the side where the
charging door is located, a launder is arranged in such
a manner that the discharge opening is located at the
center of rotation of the furnace, i.e. slightly below
the center of the furnace drum. The furnace is mounted
on a frame and rolls and may be inclined to 300 by means
of a hydraulic mechanism.
Attached to each side of the drum are two twin-coil
inductors, each rated 300 kw at 575 Volts, 50 cycles. Thus,
the furnace has a total power rating of 1200 kw and a
maximum melting rate of 4.3 tons per hour.
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Each of these inductors has its separate control
unit rated 300 kw, 575 V, 50 cycles, single-phase,
with built-in circuit breakers, autotransformer, high
and low voltage power contactors, etc.
All four power control units in turn are connected to
a single operating panel from which the entire melting
furnace is controlled automatically.
The furnace drum is lined with special refractory
insulating blocks. The approximate analysis of this ma-
terial is: 15% Al 2-03 and 52% SiO2. Expansion at 1175 C
(2150 F) Is about 0.5%. The material has a high crush
resistance and its apparent porosity is less than 20%.
The "deep connection" principle is used in construction
of the lining, using a minimum of cement, and grinding
the surfaces of contact between individual blocks. Meti-
culous care is necessary in preparing, drying, heating,
and emptying the furnace so as to insure long lining life
and economical operation of the furnace. Lining life is
further influenced by the oxygen-free copper being melted,
a metal which does not "wet" the refractory. The lining
is installed by skilled workmen who carefully follow
specifications and directions. Every block must be set
tightly and precisely into the lining to give long con-
tinuous service. Of particular importance is the accurate
positioning of the various "guide points" in the lining,
such as the opening for the launder, the inductors, and
the top bricks finishing the lining. The block forming
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the opening to receive the launder must be perfectly
bonded with the launder itself. At the inductor openings,
the lining must have a completely smooth surface on which
the Inductor will attach well.
When drying the refractory lining, it must be consi-
dered that water cannot evaporate through the outer sur-
face since this is a steel shell. Therefore, it must
leave the lining through the inner surfaces. Drying takes
about one month.
Before starting operation of the melting furnace, the.
lining is heated from the inside to at least 900 C
(1650 F). When it throws sparks, the lining temperature
is held and raised no more than 100 C (210 F) in 24 hours.
The furnace is maintained at 900 C for one or two days
before molten copper is charged.
The melting furnace inductors are also of welded-steel
construction and contain the necessary nonmagnetic sec-
tions, cores, primary coils, blowers for cooling the pri-
mary coils, and refractory material for lining the induc-
tors. Figure 4 shows a cross section of such an inductor.
-14-
In preparing the refractory lining of the inductors,
special care and techniques are required to insure long operating
life. Lining begins with the laying of asbestos and mica
sheets, continues with light linsulating bricks, and ends
with a rammed refractory for filling the joints. The
ramming mixture used is a sillimanite with the appro-
ximate analysis 41% S1O2, 562 A1203, and small amounts of
1~ . ,VVnF1?
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CaO, MgO, and Fe2O3; loss upon heating, 0.4%. Grain size
is of importance as well as moisture content, which is
about 1~% in the mixture when ready for application.
The techniques of preparing the lining and applying
the ramming material to the inductor, as well as the qua-
lity of the material, may insure a long operating life.
Normal inductor life under continuous operation appears
to be about l- years. At the Fabrika Kablova Svetozarevo,
the melting furnace inductors now have been in continuous
operation for 221 years, have remelted 35,000 tons of
copper cathodes, and are still in first class condition.
Before being put in operation, the inductors must be
air-dried for about two weeks, then dried by electric
heat for at least 3 months, keeping the lining at a
temperature between 60 and 80 C (140-180 F). During this
time, the lining is transformed into a monolithic block.
The longer it is dried, the better. After the inductor
is attached to the furnace drum, and before charging
the first molten metal, the inductor channels are heated
to at least 950 C (1740 F).
The furnace is started in operation by a charge of
molten metal, but only when the secondary coil of the
inductor has been put under voltage. Molten metal for
starting is prepared in a small portable furnace of I,-ton
capacity. The charge is poured and, if necessary, deoxi-
dized to minimize oxygen content. The furnace is then
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rotated to 300 and the first two inductors charged and
power applied at 35 kw each; the furnace is then placed
in a horizontal position and the other two inductors are
charged with molten copper in the same manner as the first
two. The molten metal surface is now covered with a char-
coal layer to prevent oxidation of the metal. This layer
is about 10-15 cm (1r-6 in.) thick and the charcoal used
has a grain size of 2.55 cm (1-2 In.). The furnace is
then slowly charged to its normal capacity with copper
cathodes. Total capacity is of the order of 13.5 tons.
The minimum metal content under operating conditions is
6.1 tons, with the furnace inclined to 18? In a clock-
wise direction.
When charging, the cathodes open the furnace charging
door by their own weight, and after they have entered
the furnace door closes by its own weight so that the
furnace practically remains closed at all times and it
is possible to maintain a protective atmosphere in it;
at the same time, charcoal consumption to cover the
molten metal is reduced:to:minimum.
Discharging speed is usually governed by the melting
furnace and by the voltage available from the power supply
lines. With full voltage available, the maximum capacity
of 4.3 ton/hour is obtained. Normal melting rates range
from 3.17 to 11.0 tons/hour. During normal operation,
furnace temperature is held to 1170-30 C (2140-2160 F),
and fluctuates within + 20 C (70 F). Temperature variations
of this order are a problem in continuous casting and
therefore a pouring furnace was provided.
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B. Electrically Heated Launder. The molten metal
flows from the melting furnace to the pouring furnace
through a closed., electrically heated launder using elec-
tric rod heating elements. The construction is shown in
Figure 5.
Electrically, the launder is divided into three sec-
tions, each of which has its control unit and autotrans-
former to regulate voltage and, thereby, temperature.
Each section is rated 7 kva, 575 V, 50 cycles, single
phase.
The launder is connected with the melting furnace
exactly at the center of rotation of the furnace so as to
take advantage of the smooth bricks to make an outlet for
the protective gas introduced at this point. At the pour-
inf furnace end of the launder, there is a 900 elbow
which forms an extension of the launder, of heat-resist-
ant steel and refractory lined; this elbow connects with
the pouring furnace and metal is charged through it into
that furnace.
A thermocouple is attached to each launder section to
control temperature which is normally held at 1030-1050 C
(1835-1920 F). Since molten metal flows through the laun-
der in a continuous stream, protected by a reducing gas,
the electric heating elements have a very long life. More
than six months pass before their efficiency decreases to
such a degree that they have to be replaced.
-1
7-
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~+VU," j? ft 4~'9
C. Pouring Furnace. This unit, too, Is of welded .a~yL
steel construction, designed to hold and oast molten cop-
per into a Junghams-Rossi continuous casting machine.
The furnace has four main parts: the furnace body, the
spout, the lid, and the inductor. The portion of the
furnace where the inductor is attached, as well as the in-
ductor itself, Is lined with a sillimanite rammed refrac-
tory applied by a special process, and the remaining por-
tions of the furnace are lined with special insulating
refractory bricks having ground surfaces. The quality of
the refractories used here is the same as for the melting
furnace. The pouring furnace spout is purposely construct-
ed of fire-resistant material and has a zirconia insert
for pouring, a silicon carbide muffle with heating elements
inserted, silicon carbide slabs, etc. Figure 6 shows a
cross section through the pouring furnace spout construc-
tion.
The drying, preheating, and initial operation has been
described in detail above and must be strictly adhered to.
The furnace is designed to be tilted forwards and back-
wards and at the same time shifted horizontally, all by a
hydraulic mechanism.
In addition to the charcoal layer on the melt, a pro-
tective atmosphere is introduced into the furnace which
penetrates into the launder and acts as protection at
this point where no other protective cover exists.
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The pouring furnace inductor is rated 100 kw, 575 V,
50 cycles, single phase. It has its own control unit and
electrical apparatus for completely automatic operation.
Installation and insulation of the inductor are the same
as for the melting furnace inductors. However, in this
case lining life normally will be about three years under
continuous operation. Figure 7 shows the pouring furnace
inductor which is of different design than the melting
furnace. Inductors.
-19-
The holding capacity of the pouring furnace is about
2.5 tons. Before tilting the furnace for pouring, metal
temperature Is increased to 1200 C (2190 F), but the normal
pouring temperature of 1150-1160 C (2105-2150 F) is reached
within the first 10-15 minutes. Temperature fluctuations
in the pouring furnace are of the order of + 2 C, a factor
of great Importance to the successful continuous casting
of this metal.
Both the pouring and melting furnaces are automatically
controlled by thermocouples and electric pyrometers re-
gistering the temperature. Otherwise, it would be impossible
to regulate furnace temperature as the furnaces are comple-
tely enclosed.
D. Junghans-Rossi Continuous Casting Machine. The only
casting method used at our plant is continuous casting with
a Junghans-Rossi machine. This machine operates at casting
speeds from 0 to 1524 mm/min. (for cross sections of l" x
14.", about 8 ton/hour). Maximum width attainable is 153 mm
(6" x 6" square) and minimum width is ~1 mm (2" x 2" square).
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Casting length is adjustable up to 1524 mm, our present
standard length being 1140 mm.
The main components of the casting machine are: the
casting table with chill mold and water sprays (upper
unit), the main drive and transport rolls (middle unit),
and the saw with its hydraulic mechanism for cutting the
wire bar (lower unit).
The chill mold is arranged in the center of the cast-
ing table, at the vertical axis of the saw clamps, with
the transport rolls holding the wire bar in position.
The casting platform moves up and down within from I"
to 1i"-, adjustable in steps of 1/8". When casting our
4" x 4" wire bars, the casting table movement is of the
order of 5/8".
Before starting operation, and after any adjustments,
the casting machine is synchronized. This means that the
downward motion of the chill mold must be the same as the
peripheral movement of the transport rolls so that there
can be no relative movement between the mold and the bar
being cast. The upward movement of the mold is about
three times the speed of the downward movement. The wire
bar is first cooled by water in the chill mold and emerges
at a temperature of 850-900 C (1560-1650 F), and is sub-
sequently cooled to room temperature by water sprays:
The cooled wire bar then passes a rubber wiper and the
water is, conducted from the cooling chamber into the sewers
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 Approved For Release 2009/07/22 : CIA-RDP80T00246AO11300260001-7
by tubes. Figure 8 shows this middle unit with the main
drive, transport rolls, and casting table mechanism.
In addition to withdrawing the wire bar from the mold
at a constant speed, which is governed by the casting
speed, the transport rolls at the same time cause the
wire bar to push down the basket receiving the cut wire
bar, thus actuating the entire flying saw operation when
the bar has reached the determined length.
The saw is completely automatic and operates with three
different- systems, hydraulic, pneumatic, and electric. As
the wire bar - withdrawn by the transport rolls at a
specified speed - strikes the bottom of the receiving
basket, it pushes the basket downwards until it reaches
its determined length. At this point, the pneumatic system
actuates the hydraulic system and starts the sawing cycle
by means of a series of valves which open and close one
after the other, and change the direction of the oil in
the lines. The saw clamps grasp the wire bar tightly and
the s*aw operating platform then moves downwards with the
wire bar through a series of steps. The motor operating the
saw blade works continuously. After the clamps have grasped
the wire bar, the saw is pushed to the wire bar horizont-
ally at a set speed by hydraulic means; the sawing speed
is adjustable, depending on casting speed and on the sharp-
nessof the saw. After the wire bar is cut, the saw is
withdrawn to its original position and the motor operating
the platform is started to bring it back to its upper
starting position. In the meantime, the basket is lowered
pneumatically and the wire bar transferred to the gravity
conveyor, whereupon the basket returns to its upper post-
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-21-
 Approved For Release 2009/07/22 : CIA-RDP80T00246AO11300260001-7
tion. The cycle is repeated for each successive cut.
Figure 9 shows the saw during the cutting operation.
The chill mold used for casting this type of copper.
differs from those used for casting copper alloys or
aluminum. It consists of a monolithic copper block with
ducts drilled in for suitable water cooling. The profile
to be cast is cut out from the center of this block and
the inner surfaces are machined, polished, and chrome-
coated (.05 mm) so as to obtain the greatest possible
smoothness and to reduce friction between cast bar and
mold surface. Accordingly, at any interruption of the
casting process and before restarting, the mold is cleaned
and polished with a special polishing material, using a
special flexible-shaft tool. Completely smooth surfaces
ire obtained in this manner and no milling of the surfaces
is required.
-22-
A hood is placed over the top of the chill mold and
a.protective atmosphere introduced so that the molten
metal will not come into contact with the air. In addition,
butane gas is introduced through a ring for lubrication;
with the high metal temperatures and in absence of air,
this decomposes into H2 and C. The carbon is precipitated
in the form of soot on the metal surface and is constantly
drawn against the mold walls where it acts as a lubricant.
The proportions of protective gas and butane in the chill
mold are of great importance for successful operation and
for the quality of the casting. Just:sufficient gas should
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be applied to force the air slowly out through the hood,
and if this is attained, the amount of butane used usually
is of 200-300 ml. With these proportions, it is obvious
that carbon settles on the metal surface, and also the
bright surface of the metal. If butane is used excessively,
spots and occlusions are formed which will appear as im-
purities on the wire bar surface.
Correct cooling in the mold is extremely important
for the continuous casting of copper. The soundness of
the casting depends on uniform cooling in the mold and by
.the sprays, and the slightest irregularity in this respect
leads to rejects. Roughly speaking, one third of the en-
tire amount of heat is removed in the mold. The remainder
is removed by the sprays. The approximate water consump-
tion of the mold for a 1L" x L1" section is 70-90 liter/min.
and 130-200 liter/min. are used in the sprays. Deoxidized
copper and copper alloys present no problem in continuous
casting, but electrolytic tough pitch copper from reverbe-
ratory furnaces has not yet been cast successfully by a
continuous process, although experiments have been made in
that direction for a long time and are still being con-
ducted.
Before casting begins, the first wire bar is inserted
about two thirds into the chill mold and the space between
mold and casting is filled with asbestos strips. The mold
table Is set at its highest position and the speed is set
for starting. Normally, casting temperature is held be-
tween 1150 and 1165 C (2100-2180 F), but for starting it
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is increased to 1200 C (2190 F) so as to prevent freezing
of the downspout; within the first 10-15 minutes, the tem-
perature is then decreased to normal. It seems obvious
that a carefully standardized procedure is required In
starting and casting.
Up to the present, the maximum production for any one day
has been 95 tons. During 1959 it reached 103 tons/day.
mal daily production runs around 80 tons.
E. Production of Protective Atmosphere. Since the
production of oxygen-free copper consists only of the con-
version of high-quality copper cathodes into suitable
shapes (in this case wire bars) for further processing -
while at the same time maintaining the quality of the
cathode metal - the remelting process is carried out
under a specially prepared protective atmosphere which
Is of primary importance to the entire production process.
,
This protective atmosphere Is produced in a group of
apparatus designed to yield as an end product the desired
gas composition. Figure 10 shows a schematic view of this
apparatus.
-24-
The equipment to produce the protective atmosphere for
the oxygen-free copper casting shop at the Fabrika Kablova
r.cohsists of the following: An apparatus to produce gas from
charcoal, a gas scrubber for washing and cleaning, an appara-
tus for removal of water vapor, and an apparatus for convert-
ing carbon dioxide into carbon monoxide, with filters.
Charcoal is burned in a.smgll "Galusha" gas producer
lined with insulating and refractory brick, and equipped
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with an air blower; normal producer gas is made with an
approximate composition of 16% H29 27% CO, 5% C02, 1% CH11,
remainder N2, and an approximate heat value of 1330 kcal/
Nm3. This generator can burn up to 20 kg of charcoal per
hour. The cold washed gas gives about 87% of the total
heat in vigorous firing, up to 1,660,000 kcal/hour. If
needed, less charcoal may be burned to produce smaller
amounts of gas per hour. Our normal production requires
about 140 kg of charcoal per day, or 5.8 kg/hour. Grain
sizes range from 50 x 50 mm to 25 x 25 mm.
The gas so produced is first cleaned in a scrubber to
remove dust and tar and, if needed, SO2. The scrubber is
filled with hard washed coke, of a grain size of 3/8" to
3/4" in the lower half, and 3/4" to 1/2" in the upper half.
Gas is discharged from the bottom; there is a water out-
let at the bottom and a water spray at the top of the
scrubber.
Charcoal was chosen as fuel because of its low sulphur
content. Since sulphur is highly detrimental in copper,
particularly in the form of H2S; nevertheless, a sulphur
remover is used which contains sawdust impregnated with
iron oxide (Fe2O 9, and the following reaction occurs as
the gas passes through this:
Fe2O3 + H2S ? Fe2S3 + H2O.
The cleaned producer gas is sent to the converter by a gas
pump with a constant pressure of 0.211 atm. The gas-air
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proportion to the converter is carefully controlled
by measuring instruments and they are mixed, compressed
and burned. The burner is located in a reaction chamber
filled with catalytic bricks of a special kind which help
to complete the combustion process. The gas from this
chamber is composed of CO2 and N 2.
Some of the moisture is removed in the converter cooler
which brings the gas to a temperature of 17-18 C. The gas
is then conducted to a refrigerator and chilled to +2 C,
thereby loosing the major amount of water.
This gas - now containing only 002 and N2 - goes to
a "drycolene" generator. This is actually a retort of heat
resistant steel, filled with charcoal of carefully con-
trolled grain size, which has its outside walls heated
so as to maintain the retort temperature and charcoal
temperature at 1050 C (1920 F). The gas enters the retort
at its lower end, passes through a layer of glowing char-
coal, and exits through a dust filter from where it goes
to the casting machine where it serves as a protection.
-26-
As the CO2 passes through the glowing charcoal at 1050 C,
it is reduced to CO, and yields a gas with the following
analysis: 20-25% CO, .5-1% CO2, .5-1% CH40 .5-1% H2, re-
mainder N2. This is the protective atmosphere which pre-
vents the molten copper from coming into contact with air.
The entire gas generating apparatus is provided with
instruments, regulating valves, safety devices, etc., to
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WIVUsdaJutu ILL
operate continuously and very quietly. Though the appa-
ratus is ideal for automatic analyzing, the gas in prin-
ciple is controlled by an Orsat apparatus. Figure 11
shows this equipment.
PROCESS AND PRODUCT CONTROL.
A method of statistical process and product control
was adopted for the casting operation. The completely
continuous melting and pouring process, together with the
full mechanization and automation, allows a high degree
of control and accuracy.
According to the manual of instructions, process con-
trol is carried out at the five key points where a cer-
tain amount of information is recorded at precisely de-
termined times to indicate the condition of that particu-
lar portion of the equipment. In addition to the standard
recording of instrument readings, every change is record-
ed together with the exact time when it occurred. This is
often accompanied by remarks and comments by the foreman
in charge of the section. By recording the process in this
way, for one thing, the foreman in charge of a section is
compelled to record readings from various instruments at
specified Intervals and note at the same time any changes
that may have occurred, and if so, take the necessary steps;
also, the total information gained in this manner from all
key points at the same time intervals give a clear picture
of the process and of its accomplishment. Based on this
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information, the process may be speeded up or slowed
down, improved upon and supervised.
_2g_
These data, collected for each shift, also serve as a
basis for daily reports on plant operations, listing all
essential data such as amount of metal melted, hourly
melting rate, average melting rate in tons per hour, amount
of metal poured, analysis of casting machine operation,
yield, amount of rejects and scrap, with analysis thereof,
electric power consumption per ton of production, con-
sumption of charcoal and other materials required in the
operation and maintenance of the plant, etc. These data
are an adequate basis for a complete economic analysis of the
plant. Evidence of this kind made it possible in the course
of this year, by supplementing the capacity and taking
other measures at the plant, to reduce electric power
consumption per tcn of finished product from 470 to 350 kwh,
consumption of charcoal from 6.1 to 4.3 kg/ton, and increase
the yield from 93.5% to 99.2%.
Control of wire bars is obtained by:
a) Visual Inspection on the conveyor:
b) Measurement of specific gravity of approximately
every thirty-fifth wire bar;
c) Testing of physical and chemical characteristics
In the plant laboratories. The physical laboratory
is equipped with a small stand of rolls and a
tensile strength machine.
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For a complete analysis of a wire bar, it is standard
procedure to take one sample for every four hours of cast-
ing, or twice per shift. With the continuous casting pro-
cess there is no danger of sudden changes in production.
Whenever smaller amounts of copper from several sources
are melted, a greater number of samples is taken.
The following tests are made for a complete analysis:
electrical conductivity, bending, torsion and rupture
tests, elongation, macro- and microstructure, and a sepa-
rately conducted embrittlement test. This last test con-
sists of the following:samples are prepared for bending
by heating for one half hour in a hydrogen atmosphere at
850 C (1560 F). In accordance with ASTM Standards B-170,
the samples must withstand at least 8-10 bends. Ordinary
electrolytic tough pitch copper with normal oxygen content
will withstand not even one bend of this test.
The following table gives comparative values for
oxygen-free copper produced at our casting shop and for
tough pitch copper from a reverberatory furnace, which
were tested at the same laboratory.
The table shows clearly the superiority of oxygen-free
copper over tough pitch copper. In analyzing these re-
sults, it should be kept in mind that the tough pitch copper
used for these tests was of the best kind known with re-
gard to purity and quality of the tough pitch copper cathode.
As further Illustration, Figure 12 shows the macrostructure
of oxygen-free copper and of tough pitch copper with about
.0459o'02. Figure 13 shows the macrostructure of oxygen-free
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continuously cast wire bar of oxygen-free copper.
Type
Specif.
Tensile Elonga-
Specif.
No.
No.
No. of
of
Gravity
Strength tion
Conduc-
of
of
Bends /
Wire
tivity
Bends
Turns
Embritti.
Bar
kg/dm3 1
kg/dm3
met/mm2
1
2
4
3
5
6
7
8
__w
FKS
.... ~. _
r
_. T ._.
~_
3.90 to
_-..
.
_b...
.._.
(oxyge
8.94 42-43.5 2
58.9 to
15-18
130
8-12
free)
59.3
-140
Toughy
Pitch
8.50 to
8.75 40-14.2 2
58.2 to
10-12
100
0.0-+
58.6
-130
Notes:
1) Tests in Columns 3 and 4 were made with hard-drawn wire,
1 mm in diameter.
2) Tests in Columns 5,6,7,3 were made with soft annealed wire,
2 mm in diameter.
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-Figure 1. General View of the Casting Platform at
Fabrika Kablova Svetozarevo.
Figure 2. Schematic diagram showing production of
oxygen-free copper at Fabrika Kablova Svetozarevo.
V Air HO-Water
G Dryco ene gas
B Butane gas
1 Cathode
2 Charcoal
3 Ajax-Scomet melting furnace
Electrically heated launder
5 Bahney pouring furnace
6 Chill mold hood
7 Chill mold
8 Direct cooling chamber
9 Transport rolls
10 Clamps
11 Saw
12 Basket to receive cut wire bar
13 Wire bar to rolling mill
14 Galusha gas producer
15 Scrubber
16 Sulphur remover
17 Gas converter
18 Refrigerating machinery
19 Drycolene generator
20 Gastex gas filter
Figure 3. Ajax-Scomet Melting Furnace. Cross Section.
Figure 4. Cross Section of Ajax-Scomet Melting Furnace
inductor.
Figure 5. Electrically Heated Launder. Cross Section.
Figure 6. Pouring Furnace. Cross Section.
1 Silicon carbide slabs
2 "Carbofrax" plug
3 Silicon carbide muffle
4 Zirconia throat and insert
5 Pouring spout
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Illustrations:
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Figure 7. Pouring Furnace Inductor. Cross Section
Figure 8. "Middle Unit" of Junghans-Rossi continuous
casting machine.
Figure 9. Flying saw for cutting wire bars during con-
tinuous casting on the Junghans-Rossi machine.
Figure 10. Schematic view of gas producing apparatus.
Figure 11. View of operating platform of the gas producer
providing the protective atmosphere.
Figure 12$ Microstructure of oxygen-free copper.
Figurel2b. Microstructure of tough pitch copper.
Figure 13. Macrostructure of oxygen-free copper wire bar
produced by continuous casting.
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44
f17
a
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I
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?
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A ri
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O&P
A".
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HFt'd.;?,~~ A',,, 7, T fie. C? a t)E>T Yt !e C.7 TT4 Y+J E0
Krap r- rrtt M"-sgngwGrk Sevolrro/JuVoskkwien
F. Pl1PENCOF,DT, .uVj i..IDursn
Jugu;lawiezt., alas weite und beliebta Reiseland von groBer,
ursprungltdaer Scionheit, hat durdi seinen vielfaltigen
Reidit.sm an Eudensc:latzer, und reine ci nstigen Wasser-
ver tar.tnisse aufSeruidentlia?e Voraus,etzungen fur eine
>dtnelle industrielle ErschlPeBung. Den zwangsiaurigeu Ent-
wicklungen der Zeit folgend, nutzt das Lard seine Mogli.-h-
keiten und befindet aide in einer U1nwdlzung suiner wirt-
sdiaftlidien Struktur. Aus der Vielfalt der groBen Irdustri-
alisL rurigsprojekte soil Tier ernes herausgenomrnen und
erlau?err werden: Das Kupfer- und Mossingwerk Sevojno.
Die anerkannt hodiwertige Kupferbasi. on Bor und Um-
gebung, in Verbindung mit Ieidien Zinkvorkomznen, deren
Verhuttungsanlagen ebenfalls groBzugig und modern aue-
gebaut worden sand, war die naturlikhe Voraussetzung iiir
deft Wunsch, ein eigenes grcBes Halbzeugwerk zu erricinten.
Die Bead?iung der Steigerung des einheimischen Bedarfs
und die Al idit, an.aatt der Bor-Kathoden weitgehend ver-
edeltes lialbzeug zu exportieren, hab."n zu dem Entsdilu13
gefi hrt, ein Werk zu bauen, dessen Grdt3enordnung den Ein-
satz moderner, leistungsstarker Maschinen und Einrich-
tungen rechtfertigt und lohnt. Mit der Gesamtplanung
wurde die Gutehoffnungchutte Sterkrade A.G. be auftragt.
Die Walzwerke und Pressen wurden von der Schloemann
A.G., Dusseldorf, geliefert und, soweit Maschinen vorhan-
den w. wren, vervnllstandigt. Die Montage, Inbetriebsetzung
and Vorfuhrung erfolgte unter Fuhruim der beiden genenn-
ten Firmen.
Als Standcrt wurde d:e Kreisstadt Titovo-Uzice bestimmt.
Uzire hat etwa 20 000 Einwohner unnl:-liegt in der Mitte
er Eisenbahnstredce Jieograd-Sarajevo Die Landwirtschaft
bietet in der bergigen Gegend our geringe Moglichkeiten.
Die W11dwirtschaft hat in den vergangenen Jahren stark
gelitten. Die in groBem Umfang durch5efiihrten Wicderauf-
forStungen brauchen Jahrzehite, bis sie wirtschaftlich ge-
nutzt werden konnen. Der Gedanke, die Wirtsdiaft diesel
Gegend zu starken und durdt das Werk neue .rwerbsmog-
lidikeite.?i zu sdeafi:: a, durfte bei der Entsdieidung fur den
Standort ausrdilaggebend gewesen sein. Da Uzice selhst
in einem engen Gebirgskessel liege, wurde 6 km entfernt
in dem bis dahin unbedeutenden Dorf Sevojno ein groB-
fl3diiger Bauplatz zur Verfiigung gestellt, der jede Erwei-
terungsmoglidikeit bietet und in unmittelbarer Nahe der
Bahn 'iegt. Vorlaufig ist das Werk auf einen Lastwagen-
park und auf die Sdimalspurbr.hn Beograd-Sarajevo ange-
wiesen. In wenigen Jahren wird jedodi Sav-otnc) Station der
Vollspurbahn sein, die Beograd mit dem im Ausbau be-
griffenen Adria-Hafen Bar vert;inden wird.
Fur den Betrieb des Metallwerk2~ niuBte zundchst im we-
sentlidren mit dem Einsatz ungelernte:, hauerlidter Arbeits-
krafte geredinet werden. Nur eine geringe Anzahl Spe-
zialisten konnte Gelegenheii zu einer kurzfristigen Aus-
bildung an ~.hnlichon jugoslawischen oder deutsdten Ar-
beitsstatten erhalten.
Da die wirtsdiaftlidi erreidibareKohla elneii ziemlich hohen
Schwefelgehalt :ind andere unangenehme Eicfensdiaften
hat, wurde in Hiablirc auf die giinstige Entwidcluna der
Stromversorgung eine vollkomme-i au% elektrisdier Energie
aufbauende Ausstattung des Werkes vorgenommen. _.edio-
lich fiir die Versorgung mit Hci3uwasser zum Anwarmen der
Beizbader, zum Spiilen und vo, allem fur die Heizung der
Werkshallen und Nebengebxude wurde ein I.esselhaus auf
der Basis von L.ignit errid-`et. Die Heizung ist so ausgelegt,
da13 trotz der GroBe der Hallen selbst bei Wintertempera-
turen von m%nus 30? C eine Hallentemperatu1? von 12 his
15? C tatsichlidt gehalten wurde.
Das Produktionsproeramm besdlrankt side aa; die handels-
iiblichen Halbzeuge wie illeccte, Bander, Rohre, Stangen
und Drahte aus Kupfer und Messing ncdr DIN.
iahkn/ggerp/oi
(
yr 'Tr Move
-U~, n^r^t?mrr^n?rnrnrmET 10
Die handelsiiblichen Kupfersorten, Messinge und Sonder-
messinge werden hergestellt. In Sevojno wird ebenfalls
leitfahiges Kupfer vom Typ SE-Cu nach DIN 1708 ge-
gossen, das audi den USA-Normen fiir die Sorte OFHC
entspricht.
Die Vorteile des kontinuierlichen GieBens haben sich bei
den hier vorliegenden Verhaltnissen voll ausgewirkt. Die
Ausbi'.dung konnte side auf einige Spezialisten konzentrie-
ren. Nur dadurdi war es moglidi, nach einem halben Jahr
Betriebszeit schon die Giel3kapazitat von 2000 t monatlich
zu tiberschreiten. Die verhdltnismdBig saubere und be-
queme Betriebsweise der Stranggiellanlagen bietet eine
erheblidie Erleiditerung fiir das Betriebspersonal. Die fii
Sevojno iiblichen Sommertemperaturen erschwereu die
Arbeit in den Warmbetrieben ohnehin erheblich.
Die medianisdie GuBbearbeitung ist mit den iiblichen Ma-
sdiinen neuester Konstruktion wie Schnellsagen, Platten-
frasmaschinen, Block-Bohr- und -Drehbanken verschiedener
Grof3e usw. ausgerii.stet. Zur Zeit wird die Sdimelzerei urn
zwei Niederfrequenzofen erweitert. Platz fiir weitere
Sdimelzofen und fiir die Aufstellung von zwei zusatzlichen
GieBanlagen ist vorgesehen. Fiir die Herstellung von Son-
derlegierungen in kleinen Mengen sind Kiihlkokillen vor-
handen. Die Gief3erei ist damit alien Anforderungen ge-
wadisen; sie arbeitet :nit giinstigen Einsatzzahlen, einer
kleinen Belegschaft und hoher Wirtschaftlidikeit.
Warmwalzwerk
In den vergangenen Jahren hat sick die Fertigungsweise
von Bledien in der NE-Metallindustrie stark gewandelt.
Die Forderungen der Verarbeiter und die Leistungen der
Walzwerksbauer zwingen den Halbzeughersteller, den alten
Weg der Blediherstellung in Einzeltafeln zu verlassen und
zur Breitbandwalzung iiberzugehen. Den technischen und
wirtschaftlichen Vorteilen dieser Methode, die sick bei der
Herstellung von Karosserie- und Weifbledien voll aus-
wirken konnen, stehen bei Kupfer und Messing meist zu
kleine Auftragseinheiten gegeniiber. Neue Bauarten von
Maschinen und Zubehor ermoglichen aber heute auch mitt-
leren Werken und soldien mit stark wediselndem Arbeits-
programm die Modernisierung ihrer Walzwerksanlagen.
Bei den fiir Sevojno vorgesahenen GrdBenordnungen war
die Planung dadurch vorgezeidinet, daB 90 % der Erzeu-
gung an Blech und Band bei Dicken von 3 mm ab warts liegen
sollte und damit zur Herstellung als Breitband geeignet
war. Mir die Fertigung der restlichen 10 % wurden zwei
vorhandene Duo-Blechgerilste alterer Bauart vorgesehen.
Im Betrieb hat sick spater erwiesen, daB selbst Bledie bis
5 mm Dicke vorteilhaft als Breitband gewalzt werden
konnen. Das Walzplattenformat von 600/170/1250 mm hat
im bearbeiteten Zustand ein Gewicht von etwa 1000 kg.
Fine wesentlidie Erhohung des Gewichtes ist vorgesehen.
Von aussdi1. ggebender Bedeutung fiir die Qualitat des fer-
tigen Breitbandes ist ein Warmband mit guten Toleranzen
und guter Oberflachenbeschaffenheit. Das aufgestellte
Gleichstrom-Duo-Reversierwalzwerk mit den Walzenabmes-
sungen 800 0 X 1600 mrl,geeignet fiir einenWalzdruck von
maximal 1000 t, erfiillt these Bedingungen. Zum Antrieb die-
nen 2 Gleichstrom-NebensdiluB-Umkehr-Walzwerksmotoren
von je 1135 kW, die stoBweise 100 % iiberlastbar sind. Dies
isi bei den eisten Stichen von.Bedeutiing. Die Kraftiiber-
tragung erfolgt fiber Pin mit der_ Motoren direlct gekuppel-
tes Hochleistungs-Stirnradgetriebe fiir ein maximales Ab-
triebsmoment von 110 mt und zur Ubertragung von normal
2 X 1135 kW und maximal 2 >: 2270 kW bei einer Touren-
reduzierung von 0 his 200/300 auf 0 bis 40/60 U/min. Die
maximale Walzgeschwindigkeit betragt 2 m/s.
Die Walzen sind in geschlossenen Einbausti cken mit preB-
fettgeschmierten Kunstharzschalen gelagert, die ein schnel-
les Auswechseln der Walzen gestatten. Die A.nstellge-
schwindigkeit betragt 7 mm/s. Um sicherzustellen, dell das
Walzgut immer gerade auslauft, kann jede Druckschraube
fiir sick unter vollem Druck mit 0,25 mm/s nachreguliert
werden. Vor und hinter dem Gerdst sind die Arbeitsrcll-
gange mit den Blockdreh- und -Zentriervorrichtungen an-
geordnet. Die Verlangerungen der Arbeitsrohgange, die
mit angeflanschten, in Walzlagern laufenden Rollenaggre-
gaten ausgeriistet sind, erlauben das Auswalzen von Ban-
dern bis etwa 30 m Lange. Das NormalmaB der Warm-
walzbander fiir Breitband von 1000 mm ist 1060/5/22 000 nim.
Die warrngewalzten Bander werden auf einer Einroll-
maschine mit maximal 1100 mnm Bandbreite gewickelt und
rollen durch Eigengewicht zu einem 3-stufigen Kiihlbett ab.
Vor der Einrollmaschine ist eine langere Kiihlstrecke ange-
ordnet, wo Kupferbander mit kraftigen Wasserstrahlen ee-
plbtzt und vor dem Einrollen abge'ciihlt werden. Zum Ab-
legen starkerer Walzplatten fiir dicke Bleche wurde die in
Abb. 5 vorn sichtbare Stapelvorriditung angeordnet, die
so ausgebildet ist, daB das Bassin mit zirkulierendem Was-
ser gefiillt werden kann, um Kupferwalzplatten ebenfalls
in einem Arbeitsgang zu plotzen.
Das Anwarmen der Walzplatien erfolgt in drei elektrisch
beheizten StoBofen mit einem AnschluBwert von je 550 kW.
Die Ofen haben 6 Regelzonen und Sind fiir eine Hochst-
temperatur von 1050c C gebaut. Ihre Leistung liegt bei 3,5 t
Walzgut je Ofen und Stunde. Die angewarmte, ausge-
stoBene Walzplatte kommt auf den in Abb. 6 siditbaren
Rollgang, der an der Ofenseite angehoben wird. Durch ihr
Eigengewicht rollt die Platte auf den Transportwagen, der
sie von dem jeweils in Betrieb befindlidien StoBofen zum
Walzwerk fahrt. Zwischen dem Plattentransportwagen und
896 Approved For Release 2009/07/22 : CIA-RDP80T00246AO11300260001-7
 Approved For Release 2009/07/22 : CIA-RDP80T00246AO11300260001-7
#di'v' '