Note: Descriptions are shown in the official language in which they were submitted.
MODIFIED METALLURGICAL CONVERTERS
AND METHOD OF REPAIRING SAME
Technical Field:
The present invention relates to metallurgical
converters and more specifically, to modified metallurgical
converters which provide easy access for the repair of its
internal refractory lining.
Background Art:
A number of metallurgical converters for copper, nickel,
lead or other nonferrous ores or the like, are well known in
the mining art. These converters generally include those
known as Peirce-Smith, Teniente, Noranda, or other similar
types.
The converters which are most commonly used are
basically characterized as having a cylindrical horizontal
shell which can be of variable dimensions depending upon the
specific production requirements. The material of
construction for the shell is generally carbon steel lined
with a refractory material in order to allow the converter to
operate properly in contact with liquid metallic elements at
temperatures of approximately 1200~C and above
The converter is used to oxidize various components of
the ores. For example, in the conversion of copper mattes,
air is introduced through molten copper matte to oxidize any
metal sulfides which are present. This oxidation is
accomplished by injecting an oxidizing agent, most commonly
air, into the molten ore bath in the converter through
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tuyeres which extend through the shell and refractory lining.
These tuyeres are located in a predetermined arrangement
usually in the bottom or lower portion of the converter
shell.
During the course of operation of the converter over an
extended time period, the refractory lining begins to wear or
deteriorate. Usually, the refractory areas adjacent to and
around the tuyeres experience the greatest wear because of
the turbulence from the introduction of the air and the
locali%ed heating caused by the reaction of the air with the
ore components. Also, the refractory lining can spall, crack
or flake if subjected to extreme temperature fluctuations.
Therefore, it becomes necessary to shut down the equipment
and repair or replace the damaged refractory lining.
Previously, the usual method of repair would be to stop
the operation of the convertor, allow it to cool to ambient
temperatures, remove the heads to facilitate entry into the
shell, and replace the damaged or deteriorated portions oE
the refractory lining. The repair or replacement of the
refractory lining is difficult and time consuming since
maintenance personnel would have to work within the converter
shell itself. In addition, the reliability of a reEractory
lining is suspect in the areas where the new or replacement
lining must be joined or bonded to the remaining portions of
the original lining. For this reason, it is Gften preferably
to replace the entire refractory lining of the vessel in
order to achieve longer service lives and more reliable
operation when the converter is put back on stream.
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Furthermore, the loss of production due to the
removal of the converter from service for a considerable
length of time and the repair cost (i.e. materials and labor)
for installing the replacement refractory lining are
relatively high. Therefore, the mining industry has long
been searching for an alternative method of reliably
repairing or maintaining these converters to avoid such long
down time periods and high repair costsO
Brief Description of the Invention
The applicant has discovered that modifying the steel
shell of the converter by installing easily removable shell
portions or segments in the areas which are expected to
receive the most severe service, such as the tuyere zones,
allows the refractory lining in this zone to be easily
replaced or repaired without having to replace the entire
refractory lining of the converter or first cool the unit to
room temperature The modified converter of the invention
and the method for its repair represent numerous advantages
due to the shorter repair time involved, which in turn means
greater operating availability and greater associated
productivity; conservation of repair material and labor
costs; more convenient working conditions for maintenance
personnel; an more reliable operation of the converter when
it is returned to service.
Summary of the Invention
The present invention relates to an improved
metallurgical converter having a cylindrical shell which is
lined with a refractory material wherein the shell of the
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converter is modified by providing a plurality of removable
segments or portions in the areas where the greatest degree
of lining deterioration is anticipated. Each segment is
connected to the remainder of the shell by a flange and bolt
assembly to Eacilitate its removal and replacement.
Furthermore the removal of each segment can preferably be
effected from the outside of the converter
Another aspect of this modified metallurgical converter
relates to the modification of the shell to provide a
plurality of removable segmented portions around the tuyere
area. Again, each segment is connected to the remainder of
the shell by a flange and bolt assembly to facilitate their
removal and replacement, and each segment can preferably be
removed or replaced from the outside of the converter.
Another aspect of the invention relates to the
improvement of the shell of a metallurgical converter wherein
a plurality of segmented portions are provided in the zones
of most frequent repair. These segmented portions have
connection means to facilitate easy attachment to and
removal from the remaining portion of the converter shell.
Preferably, the connection means comprises a flange along the
longitudinal edges of the segmented portions and a
corresponding mating flange on the longitudinal edges of the
remaining portion of the shell. Also, the flanges of the
segmented and remaining portions are advantageously joined by
bolting means.
Another embodiment of the invention relates to a method
for repairing deteriorated refractory portions oE a modified
metallurgical converter as described hereinabove which
comprises stopping the operation of the converter; removing
the segmented portions containing the damaged refractory
lining without cooling the converter from its operating
temperatures; and reattaching the segments having a replaced
or repaired refractory lining to the converter shell.
Another method of the invention relates to the repair of
damaged or deteriorated areas of the refractory lining of a
metallurgical converter wherein the portions or segments of
the converter shell which are anticipated to experience the
greatest wear are configured, dimensioned, and positioned to
acilitate easy removal and replacement. These portions or
segments can be removed and replaced without the necessity of
cooling the converter to ambient temperatures, and preferably
can be removed and replaced from the outside of the
converter.
lso disclosed herein is a specific method for repairing
the deteriorated refractory lining around the tuyeres of a
metallurgical converter wherein portions or segments of the
shell encompassing the tuyeres and adjacent areas where wear
of the refractory lining is anticipated, are configured,
dimensioned and positioned to facilitate easy removal and
replacement from the outside of the converter without having
to cool the converter to ambient temperatures.
A further embodiment OL the invention relates to a
method for extending the service life of a metallurgical
converter which comprises modifying the converter by
installing easily removable portions or segments in the shell
in the areas which are expected to experience the highest
wear or use during operation.
Further benefits and advantages of the invention will
become apparent from a consideration of the following
description given with reference to the accompanying drawing
figures which specify and show preferred embodiments of the
present invention.
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srief Description of the Drawings
Fig. 1 is a front view of a prior art converter unit;
Fig. 2 is a side view of the converter of Fig. l;
Fig. 3 is a front view of a converter unit according to
the present invention;
Fig. 4. is a detail of a removable section of the shell
of the converter of Fig. 3; and
Fig. 5 is a side view of the removable shell section of
Fig. 4.
Detailed Description of the Preferred Embodiments
The pyrometallurgical processes used for the production
of copper from copper sulfide concentrates comprise the
stages of smelting followed by converting. The first stage
is ordinarily carried out in a static furnace, the most
common of which is a reverberatory furnace, such as an
Outokumpu or INCO flash furnace. The conversion process is
usually carried out in Peirce-Smith horizontal converters
Other modern processes, such as those used by Noranda and El
Teniente, use converters that completely or at least
partially combine these two stages.
A common characteristic of the above-mentioned processes
is the use of the horizontal Peirce-Smith converter furnace
as the main equipment item for producing blister copper. A
typical prior art converter is shown in Figs. 1 and 2. This
converter 7 consists of a metal cylinder 1 having means for
rotary motion 2. The cylinder or shell 1 is lined with a
refractory material (not shown) and has an outlet 3 for the
discharge of gases.
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The oxidizing gas, which is used to promote reactions in
the converter, is injected through tuyeres 4, which are
tubular openings of approximately 2 inches in diameter, made
horizontally or at a slight angle along at least part and
preferably the entire length of the shell at a given
location. These tuyere openings are usually located under
the central shalt of the converter when the latter i5 in its
operating position. This arrangement is illustrated in Fig.
1. The tuyeres introduce the oxidizing gas from a gas
distributing system to the molten metal bath in the shell.
In the conversion of copper matte, the bath contains copper
sulfide and molten copper. Thus, special steel tubes of
approximately 2 inches winner diameter), suitably connected
to an air distributing system 5, are inserted inko openings
made through the refractory metal lining.
The refractory lining is selected based on the
particular requirements of the type of operation carried out
in the converter. Over time, this lining undergoes gradual
deterioration which is reflected in wear of the refractory
lining. Over the course of its service life, the thickness
of the lining is reduced to a limit that impairs the strength
of the shell and the operating efficiency of the converter.
At that time, the equipment has to be shut down in order to
undergo an overhaul, which primarily includes replacement of
the worn portions of the refractory lining which might
jeopardize the continuous operation of the unit when returned
to service. The time normally employed in carrying out this
overhaul, calculated from the time when the equipment stops
operating until it is returned to service, is 12 to 20 hours,
depending on the type of converter. This period includes the
time necessary to cool the unit to ambient temperatures as
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well as to reheat the unit to working temperatures. This
downtime represents a significant loss of production
capacity.
The present mode of operation of these converters causes
the greatest wear of the refractory lining in the areas
surrounding the tuyeres and the zones adjacent thereto. TAe
wear in these areas determines when the converter must be
removed from operation for repair of the refractory lining.
Since the repair of the refractory lining necessitates
cooling ox the converter to ambient temperatures. This, in
turn, detrimentally afEects the useEul life of the unworn
portions of the refractory lining, which requires more
frequent future repairs. Thus, the reliability of the
convertor is reduced and maintenance costs are increased.
In order to increase the availability and reliability of
this equipment, the applicant has discovered a way to modify
the shell of the converter which then makes it possible to
completely replace the worn portions of the refractory lining
from the outside of the converter without having to cool the
unit to room temperature. Usually, the portions of the
refractory lining which experience the greatest wear occurs
around the tuyeres.
A preferred embodiment of the present invention consists
of a metallurgical converter as shown in Figs. 3-5. This
modification is based on the provision oE a segmented
converter shell in the tuyere zone 10. By making each
seyment 11 easily removable, it becomes possible -to
expeditiously replace the refractory material of this zone of
the converter _.
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Each segment section of the shell includes a given
number of tuyeres and in turn defines a number of courses of
a refractory or brick over and under the tuyere zone. The
amount of brick or refractory reinforcement in this area
depends on the anticipated type and degree of wear in that
zone. The length of the segments depends on the length of
the equipment, the number of tuyeres required by the
converter, and the facilities available at the plant for
removing these segments. These segments consist of equal
portions of rectangular shapes which follow the curvature of
the she]l. The remaining portion of the shell and the
segments have, on their longitudinal edges, flanges 12
projecting toward the outside of the converter, which
facilitate the joining of the segments to the shell by bolts
without the converter losing any mechanical strength compared
to an integral (i.e., non-segmented) converter unit.
The principal operations carried out in the preferred
repair of the refractory material of the tuyere zone in the
modified converters of the present invention is as follows:
a) stop operation of the converter, without cooling
the unit from its working temperature;
b) disconnect the tubes of the air distributing
system;
c) loosen the bolts which connect the flanges oE
the segments and shell;
d) remove the segments from the outside;
e) replace the refractory lining of etch segment;
f) replace the metal segments into the shells; and
g) reconnect the air distributing system to the
tuyeres.
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This modification in design and simple procedure for
repair of the metallurgical converters of the present
invention, is applicable to many typ0s of converters in the
metals industry, preferably for the conversion of nonferrous
metals such as copper, nickel, lead and the like. This
simple system presents significant advantages over the
traditional repair procedures for this equipment, including:
1) increasing the availability of the converter by
appreciably reducing the repair time, which allows
greater productivity of the equipment;
2) reducing the cost of future repairs and increasing
the reliability and useful life by of the undeteriorated
portions of the refractory lining of the converter by
avoiding the detrimental effect caused by cooling to
ambient temperatures;
3) improving and simplifying the working conditions for
repair and maintenance personnel;
4) applying this procedure to any portion of the shell
that may require more frequent repair of the refractory
lining.
While it is apparent that the invention herein
disclosed .is well calculated to fulfill the desired
results, it will be appreciated that numerous
modifications and embodiments may be devised by those
skilled in the art, and it is intended that the appended
claims cover all such modiEications and embodiments as
fall wi-thin the true spirit and scope of the present
invention.
