U.S. patent application number 09/974199 was filed with the patent office on 2003-04-10 for method of melting a mixture of scrap metal using scrap rubber.
Invention is credited to Stebbing, Franklin Leroy.
Application Number | 20030066387 09/974199 |
Document ID | / |
Family ID | 29216541 |
Filed Date | 2003-04-10 |
United States Patent
Application |
20030066387 |
Kind Code |
A1 |
Stebbing, Franklin Leroy |
April 10, 2003 |
Method of melting a mixture of scrap metal using scrap rubber
Abstract
A process for melting scrap metal for producing steel which
includes the steps of combining a quantity of scrap metal
containing steel and at least about 0.25 percent by weight of scrap
rubber in an electric arc furnace. Energy is then applied to the
quantity of steel and scrap rubber in the furnace to start the
combustion of the scrap rubber to add additional heat for melting
the scrap metal containing steel.
Inventors: |
Stebbing, Franklin Leroy;
(Norfolk, NE) |
Correspondence
Address: |
LAW OFFICES OF ADAM H. JACOBS
PATENT ATTORNEY
1904 FARNAM STREET, SUITE 726
OMAHA
NE
68102
US
|
Family ID: |
29216541 |
Appl. No.: |
09/974199 |
Filed: |
October 10, 2001 |
Current U.S.
Class: |
75/10.61 |
Current CPC
Class: |
F27D 2099/0051 20130101;
Y02P 10/20 20151101; C21C 5/5252 20130101; C21C 5/5211 20130101;
C21C 5/527 20130101; Y02P 10/212 20151101; F27B 3/183 20130101;
C21C 2005/5282 20130101 |
Class at
Publication: |
75/10.61 |
International
Class: |
C21C 005/52 |
Claims
I claim:
1. A process for melting metal for producing steel comprising:
combining a quantity comprising metal containing steel and at least
about 0.25 percent by weight of shredded/chopped scrap rubber;
inserting said quantity into an electric arc furnace; and applying
energy to said quantity in said furnace to start the combustion of
said shredded/chopped scrap rubber to add additional heat for
melting said metal containing steel.
2. The process of claim 1 further comprising using oxygen/natural
gas burners to supply a portion of said energy.
3. The process of claim 2 further comprising turning off said
natural gas but continuing the supply of oxygen once said scrap
rubber tires have been ignited.
4. The process of claim 1 wherein said shredded/chopped scrap
rubber includes an amount of steel belted rubber tire sections and
pieces that is greater than an amount of non-steel belted rubber
tire sections and pieces.
5. The process of claim 1 wherein said addition of said shredded
scrap tires to said furnace catalyzes carbon monoxide conversion to
carbon dioxide to substantially reduce carbon monoxide emissions
and thereby substantially reduce pollution levels emitted from the
furnace.
6. A process for melting metal for producing steel in a furnace
comprising: providing a scrap tire ignition container positioned
adjacent the furnace and in heat and material transfer connection
therewith, said scrap tire container including a quantity of scrap
rubber therein; igniting said scrap rubber in said scrap tire
container such that heat is produced; and utilizing and
transferring heat generated by said ignited scrap rubber in said
scrap tire container to said metal in a furnace to heat said metal
in said furnace to reduce the amount of external energy required to
be applied to said furnace for melting of said metal whereby the
efficiency of said furnace is increased.
7. The process of claim 6 wherein said scrap rubber comprises at
least some metal-belted tires each of which includes an amount of
metal, said scrap rubber being ignited under controlled oxygen
levels to enable decomposition of at least most of said scrap
rubber into combustible liquids and gases, said combustible liquids
and gasses being transferable to locations for further burning with
said amount of metal separating from said combustible liquids and
gasses for disposal thereof.
8. A process for melting metal for producing steel in a metal feed
furnace which includes a feed device for transferring metal from a
deposit location to the furnace, said process comprising:
depositing a quantity of metal containing steel on the feed device;
adding at least about 0.25 percent by weight of shredded/chopped
scrap rubber to said quantity of metal on the feed device
immediately prior to insertion of said shredded/chopped scrap
rubber and said quantity of metal into the furnace thereby
preventing premature ignition of said shredded/chopped scrap
rubber; and applying energy to said quantity in said furnace to
start the combustion of said shredded/chopped scrap rubber to add
additional heat for melting said metal.
9. A process for melting metal for producing steel comprising:
combining a quantity comprising metal containing steel and at least
about 0.25 percent by weight of shredded/chopped scrap rubber in at
least one bundle; placing said at least one bundle in an electric
arc furnace; and applying energy to said at least one bundle in
said furnace to start the combustion of said shredded/chopped scrap
rubber to add additional heat for melting said metal.
10. The process of claim 9 wherein said bundle comprises a
conglomeration of metal containing steel and shredded/chopped scrap
rubber mixed together prior to insertion into an electric arc
furnace.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to the filing date of
related patent application Ser. No. 09/311,401 filed May 13,
1999.
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field
[0003] This invention relates generally to the manufacturing of
steel in a furnace and more particularly to the manufacturing of
steel from scrap metal in an electric arc furnace using scrap
automotive tires as an auxiliary heat supplying source.
[0004] 2. Description of the Prior Art
[0005] Scrap automotive tires present an environmental problem and
recycling is practically nonexistent. Tires do not degrade in
landfills and when stockpiled, create a major fire hazard that is
impossible to extinguish once ignited. Since they have about the
same heating value as coke, 15,000 BTU's per pound, a tire weighing
about 20 pounds has approximately 300,000 BTU's. The scrap
automotive tires are so plentiful that they have a near zero cost.
At the present time, scrap automotive tires are being used as fuel
or auxiliary fuel in a variety of operations such as cement kilns,
coal fired generators and other applications wherein a controlled
firing rate is used. In such instances, it is often necessary to
shred the scrap automotive tires prior to using in a furnace. Also,
when the scrap automotive tires contain steel belts, it is often
necessary to remove the steel belts. In some instances whole rubber
tires have been used but such use required equipment changes that
reduced the cost advantages. In the manufacturing of steel from
scrap metal, some of the steel mills add coke or coal to the scrap
metal that is melted in a furnace such as an electric arc
furnace.
[0006] An Electric Arc Furnace (EAF) is not an ordinary furnace in
any sense of the word. It is a vessel for melting steel and
providing metallurgical processing. It is believed that the EAF is
the best choice for use of the tires, or as it is often referred
to, tire derived fuel ("TDF"), as it can overcome all of the
specific problems associated with the steel belts and beads when
using TDF.
[0007] Tires are sometimes used as a fuel or supplemental fuel in
the generation of electric power. Because of the problems created
by the steel in the TDF they are not widely used or accepted as a
fuel by electric utilities. Whether or not tires are used, the
electric power has to be converted to higher voltages, transmitted
to the steel mill and then converted back into heat by the electric
arc. By using tires directly as energy in the steel furnace all of
the losses in transmission and conversion are eliminated.
[0008] Because of the problems created by the steel belts and
beads, the amount of tires now being used is not large enough to
consume the amount of tires generated each year as scrap. TDF is
the largest use for scrap tire disposal but the amount of tires
scraped each year far exceeds the number that can be consumed by
all of the various outlets combined. A large portion are shredded
and buried in landfills. Only the steel industry, as a very large
consumer of energy, has the capability to consume tires in an
amount approaching that of the rate of disposal. Therefore, it
should be noted that not only does the burning of tires for fuel
increase the efficiency of the EAF, it also provides a unique
solution for disposing of tires in an environmentally sound method.
It provides an alternative to wasting and squandering valuable
energy at a time when energy is becoming more scarce and costly.
Furthermore, even when the steel industry decides to reuse the
steel belts from the tires, the tires are stripped or shredded to
remove the rubber to access the steel belts. Much of the rubber is
then discarded, which provides only a limited solution to the
problem of the waste rubber. There is therefore a need for a
process which will utilize both the steel and the rubber found in
most tires, and which does so in an efficient and productive
manner.
[0009] In the EAF, coal or coke is added to the scrap charge as a
source of chemical energy but also as an additional source of
carbon for the steel being manufactured. The addition of rubber
reduces or eliminates the need for coal or coke as a carbon source
for steel chemistry requirements.
[0010] Therefore, an object of the present invention is to provide
an improved method of melting scrap metal using scrap rubber.
[0011] Another object of the present invention is to provide an
improved method of melting scrap metal using scrap rubber which
includes the steps of combining a quantity comprising scrap metal
containing steel and at least about 0.25 percent by weight of scrap
rubber, forming a bundle of the combined scrap metal and scrap
rubber, placing the bundle in an electric arc furnace and applying
energy to the quantity in the furnace to start the combustion of
the scrap rubber to add additional heat for melting the scrap metal
containing steel.
[0012] Another object of the present invention is to provide an
improved method of melting scrap metal using scrap rubber which
will use various types of scrap rubber, including chopped, shredded
and even whole tires baled and unbaled, both with the steel belt
included and without.
[0013] Another object of the present invention is to provide an
improved method of melting scrap metal using scrap rubber in which
the pollution emitted from the steel plant is greatly reduced,
because, specifically, when scrap rubber tires are added to the
melting steel, the carbon monoxide emissions that normally occur
from the arc furnace are greatly reduced.
[0014] Another object of the present invention is to provide an
improved method of melting scrap metal using scrap rubber which
includes a separate burning container for the tires which is in
fluid transmission connection with the furnace such that the heat
produced by the burning tires in the container is transferable to
the furnace without adding impurities caused by the introduction of
steel belts from the tires.
[0015] Finally, an object of the present invention is to provide an
improved method of melting scrap metal using scrap rubber which is
safe, efficient and environmentally sound in use.
SUMMARY OF THE INVENTION
[0016] This invention relates to a method for melting steel using
scrap metal and at least about 0.25 percent by weight of scrap
rubber, such as scrap automotive tires, wherein scrap metal and
scrap rubber tires are deposited in a steel melting furnace, such
as an electric arc furnace, and the scrap rubber tires or pieces
thereof are combusted with air or oxygen to provide an auxiliary
source of heat to melt the scrap metal.
[0017] In the preferred embodiment of the invention, an electric
arc furnace is used. In the preferred method, a quantity of scrap
metal with or without rubber is deposited in the electric arc
furnace and heat is applied thereto to form a molten pool of metal.
The scrap metal is the conventional scrap metal used to make steel.
A quantity of scrap rubber, preferably scrap rubber tires, in an
amount of at least 0.25 percent by weight, is then loaded into a
bottom opening bucket and another quantity of scrap metal is loaded
into the bucket on top of the scrap rubber tires. The bottom of the
bucket is then opened and the scrap rubber tires fall into the
electric arc furnace followed by the scrap metal. If desired, some
of the scrap rubber tires could be included in the first quantity
of scrap metal melted in the furnace. In addition to the
electrodes, the furnace may have oxygen/air blow pipes or
oxygen/natural gas burners to assist in the melting of the scrap
metal and in the combustion of the scrap rubber tires. The scrap
rubber tires ignite and are combusted to add auxiliary heat to the
furnace. Once the scrap rubber tires are ignited, the natural gas
is turned off and the oxygen is available for the combustion of the
scrap rubber tires. The electrodes in the electric arc furnace
continue to operate and function to control the temperature in the
furnace. Additional charges of scrap metal or scrap metal and scrap
rubber are subsequently added into the furnace until its capacity
has been reached. Of course, the temperature in the furnace would
preferably be the temperature normally used in the making of steel
from scrap metal which is about 2950 degrees Fahrenheit.
[0018] In another preferred embodiment of the invention, a
container for the pyrolysis of the scrap whole, or cut, or shredded
and de-wired rubber tires is located adjacent to an electric arc
furnace. Hot exhaust gases from the electric arc furnace are fed
into a jacket surrounding the container to heat the whole, cut or
shredded and de-wired rubber tires and convert them to combustible
liquids and gases. Suitable control means are provided to feed the
resulting combustibles into the electric arc furnace to function as
an auxiliary source of heat during the combustion thereof.
[0019] In still another embodiment of the present invention, the
scrap metal and scrap rubber are combined to form a scrap metal and
rubber bundle, with the scrap rubber intermixed with the scrap
metal. The metal acts as a flame retardant and also as a heat sink,
thereby preventing rapid and uncontrolled burning of the scrap
rubber. Further, the bundles may be picked up by a scrap magnet
much as is done with the standard scrap metal bundles found in the
industry today. The scrap metal/scrap rubber bundle thus provides a
controlled rate of burning while also permitting relatively easy
handling of the scrap rubber and scrap metal.
[0020] In yet another embodiment, the shredded rubber is added and
intermixed with the shredded steel scrap to form a generally
homogenous mixture. This mixture can then be readily handled by a
magnet for easy insertion of the mixture into the EAF. It is thus
seen that the present invention provides a substantial improvement
over the prior art.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a schematic illustration of apparatus for use in
one preferred embodiment of the invention.
[0022] FIG. 2 is a schematic illustration of apparatus for use in
another preferred embodiment of the invention.
[0023] FIG. 3 is a schematic illustration of apparatus for use in
yet another preferred embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0024] The present invention is shown best in FIG. 1, which
illustrates an electric arc furnace 2 of the type generally used in
a manufacturing operation to convert scrap metal into steel and is
provided with a pouring spout 4, bottom tap (not shown) or the
like. The roof 6 with the electrodes 8 has been raised and swung
aside. A charging bucket 10 having bottom doors 12 has been
positioned over the electric arc furnace 2 and is supported by a
pair of hooks 14 (only one shown) engaging outward projecting
integral studs 16 (only one shown). The hooks 14 are part of a
conventional crane (not shown) which moves the charging bucket 10
to the position over the electric arc furnace. Oxygen/natural gas
burners 18 extend through the sidewall or roof of the electric arc
furnace and are used to assist in the melting of the scrap metal
and the ignition of scrap rubber tires as described below. Once the
scrap rubber tires have been ignited, the natural gas is turned off
and the oxygen is available for the combustion of the scrap rubber
tires.
[0025] It is to be understood that although the present invention
is described as using a charging bucket to add the scrap metal and
rubber, more modern plants may add the scrap metal to the arc
furnace via conveyors or shafts which permit the furnace to remain
closed during the adding of scrap metal. The scrap rubber would be
added to the conveyor or shaft in the desired amounts and at the
proper time and location to enable the method of the present
invention to be employed.
[0026] In a preferred process of this invention, a first quantity
of scrap metal (not shown) of the type conventionally used in the
manufacture of steel from scrap metal has been loaded into the
charging bucket 10 and moved to the position illustrated in FIG. 1.
A quantity of scrap rubber tires is also placed in the charging
bucket 10 and the scrap metal and rubber is then dropped into the
electric arc furnace 2. The charging bucket 10 is then removed and
the roof 6 with the electrodes 8 mounted thereon is moved to an
operating position in the electric arc furnace 2. An electric
current is supplied to the electrodes 8 and the oxygen/natural gas
burners 18 are ignited to generate heat to melt the scrap metal. In
one example of the process using an electric arc furnace having a
capacity of 100,000 pounds, the first quantity of scrap metal
comprised 30,000 pounds and the first quantity of scrap rubber
comprised approximately 1,000 pounds.
[0027] During the melting of the first quantity of scrap metal, the
charging bucket 10 is loaded with a second quantity of materials.
The second quantity of materials comprises a quantity of scrap
rubber tires which are first loaded into the charging bucket and a
second quantity of scrap metal that is loaded into the charging
bucket on top of the scrap rubber tires. It is important to note
that various forms of scrap rubber tires can be used with the
method of the present invention, including chopped, shredded, whole
tires and even tire bales, both with the scrap steel included and
without. It has been found that depending upon the desired rate of
burn (infusion of energy from the burning tires), the size and
amount of the scrap tire pieces can be modified and changed, with
the quickest heat addition coming when shredded tires are used and
the longest lasting heat addition coming when whole tires are used.
The heat influx provided by the tires can be calculated such that a
practitioner of the present invention would be able to generally
control the amount and timing of heat influx, which is critical in
the operation of the EAF and in the creation of certain alloys and
other metal combinations.
[0028] After the charging bucket is filled with the scrap rubber
tires and the scrap metal, the roof 6 with the electrodes 8 is
raised and swung aside. The charging bucket 10 is moved to a
position over the electric arc furnace 2 and the bottom doors 12
are opened to drop the scrap rubber tires followed by the
additional scrap metal into the electric are furnace 2. The
charging bucket is moved out of the way and the roof 6 with the
electrodes 8 is moved back onto the electric arc furnace 2. The
heat of the molten scrap metal in the electric arc furnace 2 and
the heat generated by the electrodes 8 together with the
oxygen/natural gas burners 18 in the furnace function to ignite the
scrap rubber tires and their combustion with air or oxygen
functions to produce auxiliary heat to heat the additional scrap
metal as the heat moves through the additional scrap metal. The
electrodes 8 continue to operate to control the temperature of the
molten material and to assist in the melting of the additional
scrap metal but the power supplied to the electrodes 8 is reduced
as a result of the heat generated by the combustion of the scrap
rubber tires. As stated above, once the scrap rubber tires have
been ignited, the natural gas is turned off and the oxygen is
available for the combustion of the scrap rubber tires. If the
electric arc furnace 2 is not equipped with oxygen/natural gas
burners, a conventional lance or blow pipe may be used to provide
the oxygen for the combustion of the scrap rubber tires, in
addition to other methods such as the admission of air into the
furnace through doors, dampers or other such openings. In
accordance with the example described above, the second quantity of
materials comprises about 600 pounds of scrap rubber tires and
about 30,000 pounds of additional scrap metal. The temperature in
the electric arc furnace is the conventional temperature used to
melt scrap metal which is about 2950 degrees Fahrenheit. If
desired, a quantity of the scrap rubber tires, such as about 100 to
1000 pounds, can be included with the first quantity of scrap
metal.
[0029] During the melting of the second quantity of scrap metal, a
second quantity of materials comprising a second quantity of scrap
rubber tires and a third quantity of scrap metal is loaded into the
charging bucket 10. When the second quantity of scrap metal has
been melted, the roof 6 with the electrodes 8 and the charging
bucket 10 are moved to drop the third quantity of scrap metal into
the electric arc furnace 2, the charging bucket 10 is moved away
and the roof 6 with the electrodes 8 are moved back into the
operating position. In accordance with the example described above,
the second quantity of scrap rubber tires is about 500 pounds and
the third quantity of scrap metal is about 20,000 pounds.
[0030] The process is then repeated to add a third quantity of
materials comprising a third quantity of scrap rubber tires and a
fourth quantity of scrap metal necessary to reach the capacity of
the electric arc furnace 2. If the scrap rubber tires have steel
belts, then the steel in the steel belts becomes part of the molten
steel in the electric arc furnace 2. The third quantity of scrap
rubber tires is in an amount of about 500 pounds.
[0031] In the example described above, the second quantity of
materials was added to the electric arc furnace 2 about 15 minutes
after the current was supplied to the electrodes to commence the
melting of the first quantity of scrap metal. The third and fourth
quantities of materials are added in successive intervals spaced
about 15 minutes apart. After about another 15 minutes, normal
refining processes are performed on the molten metal to obtain
desired characteristics. It is to be understood that the foregoing
is only an example and that other quantities and ratios of scrap
metal and scrap tires and other sizes of furnaces may be used.
[0032] While it may be preferable in general melting processes to
use whole scrap rubber tires so as to control the combustion
thereof, if shredded scrap rubber tire were to be used, the
combustion would occur very rapidly and generate an amount of heat
far greater than that produced by the combustion of the whole scrap
rubber tires. A variation for additional control of combustion is
shown in FIG. 3 in which scrap metal and scrap tire bundles 50 are
dropped into a furnace 40 through an optimally located opening 46,
the furnace 40 already containing a quantity of molten scrap metal
and unmelted scrap 48. Two oxy/fuel burners 42a and 42b extend into
the furnace 40 for igniting the tires and providing combustion
oxygen. As the scrap tires burn, energy is added to the mass of
scrap metal 48 and the scrap metal in the bundles and the remaining
unmelted scrap metal is melted at a faster and more efficient rate
than that ordinarily obtained. Molten slag floats to the top of the
molten metal and the molten scrap metal is then poured out of the
furnace 40 through pouring spout 44. This embodiment presents
significant advantages over the prior art and even is superior to
merely combining the scrap rubber in the metal. With the scrap
metal and scrap rubber being combined to form a scrap metal and
rubber bundle, i.e., the scrap rubber intermixed with the scrap
metal, the metal acts as a flame-spread reducer and also as a heat
sink, thereby preventing rapid and uncontrolled burning of the
scrap rubber. Further, the bundles may be picked up by a scrap
magnet much as is done with the standard scrap metal bundles found
in the industry today. The scrap metal/scrap rubber bundle thus
provides a controlled rate of burning while also permitting
relatively easy handling of the scrap rubber and scrap metal.
[0033] An additional important feature of the present invention is
that the pollution emitted from the steel plant is greatly reduced
when scrap rubber tires are added to the melting steel. When tires
are added to the scrap metal the carbon monoxide emissions that
normally occur from the arc furnace are greatly reduced. The tires
act as a catalyst for carbon monoxide to carbon dioxide conversion.
This also results in a much greater release of usable energy inside
the furnace converting the energy therein where it has the most
benefit for the melting of the steel. When conventional coal or
coke is used, a lot of the available chemical energy is lost
because the carbon in the fuel does not completely convert to
carbon dioxide during the burning process. Numerous studies have
been done looking into ways to increase the conversion rate and
thus increase the efficiency of the melting process, including such
methods as additional oxygen injection and other such techniques.
The scrap rubber tires used in the method of the present invention
provide at least a partial solution to this problem even if used
only as a supplement to the coal or coke just for this purpose.
More than half of the available energy is lost if the carbon is not
allowed to react all the way to CO.sub.2. Often the carbon monoxide
converts in the duct system outside of the furnace resulting in
wasted energy, duct damage or even explosion, as it is a
combustible gas. It has been found that the addition of the scrap
tires as taught in the present invention will at least provide a
partial solution to these problems. The inclusion of scrap tires in
the melting process also has been shown to reduce NOx and SO.sub.2
emissions when properly combusted in the EAF. This is another very
important environmental consideration in steel mill operations and
environmental operating permit compliance.
[0034] The use of TDF in the EAF also reduces the air pollution
from the EAF process. TDF contains less carbon and therefore
produces less carbon dioxide than coal or coke whether it is burned
at the EAF or back at the electric utility. TDF contains twice as
much hydrogen and burns hotter, i.e., it contains more fuel value.
Additionally the hydrogen acts as a catalyst and reduces CO
emissions, a very important and environmentally significant goal in
the steel industry. The shredded tires can also be mixed with coal
or coke and used to reduce CO emissions with a result being a
greatly increased energy release from CO to CO.sub.2
conversion.
[0035] An apparatus for practicing another preferred embodiment of
the invention is schematically illustrated in FIG. 2. Apparatuses
similar to that shown in FIG. 1 have been given the same reference
numerals. In FIG. 2, a container 20 is mounted at a fixed location
by conventional mounting means (not shown) so that it is close to
the electric arc furnace 2 and has a removable control damper/cover
22 which is used to adjust the amount of combustible air available
to the tires 100 which are to be burned within the container 20
thus regulating the rate of heat in the process. At least one
oxy/gas burner 18 is connected to the container 20 to ignite the
tires 100 within the container 20, the oxy/gas burner 18 operating
in a manner similar to that described previously in connection with
the first embodiment. A pipe 30 extends between and is in fluid
communication with the container 20 and the electric arc furnace 2.
A fume collecting system duct 24 is in fluid communication with the
interior of the electric arc furnace 2 so that the heat generated
by the burning of the tires 100 is drawn into the electric arc
furnace 2, the heat passing through the fume collecting system duct
24. A molten metal conduit 4 is in fluid communication with the
electric arc furnace 2 for releasing the molten metal from the
electric arc furnace 2. As the fume collecting system duct 24 draws
the superheated air from the container 20 into the electric arc
furnace 2 around the metal being melted in the electric arc furnace
2, the heat generated by the burning tires adds to the heat
generated by the oxy/gas burners in the electric arc furnace 2 thus
decreasing the time and energy required to melt the steel and thus
lowering the cost of steel production.
[0036] In practice, a quantity of whole, cut or shredded and
de-wired rubber tires (not shown) is deposited into the container
20 and the oxy/gas burners 18 are used to ignite the whole, cut or
shredded and de-wired rubber tires 100 to form combustible liquids
and gases. The combustible liquids and gases flow through the pipe
30 thus adding their energy produced by combustion to the steel
being melted in the electric arc furnace 2.
[0037] Still another embodiment of the present invention would
include a somewhat modified container 20 as described in connection
with FIG. 2. One of the problems with using tire derived fuel is
the steel belts and beads that they contain. The steel generally
does not belong in a combustion chamber as typically found in a
coal or gas fired boiler or similar fuel burning system.
[0038] The tire-burning container 20 is a type of burner with tires
as the fuel and with a supply of air or oxygen like most any
conventional burner, similar to what was described previously. In
this embodiment, however, the container 20 would include at the
bottom of the container a cleanout opening for the metal residue.
The tires in the container would be ignited so that they would
decompose into combustible vapors and gasses. Just enough oxygen
would be supplied to maintain this state, thus causing the tires to
melt with the metal within the tires beginning to separate
therefrom. The combustibles would then flow to an area where they
would be mixed with additional oxygen and blown or drawn into the
area where the heat was needed, such as a boiler or similar furnace
firebox. The metal would separate and settle to the bottom of the
container, as the melting point of the metal is higher than the
melting point of the rubber. Not enough heat would be generated to
melt the steel, just enough to separate the rubber materials from
the steel. In this manner, the tires are broken down into
combustible fluids that can be moved into an area where they can be
burned as fuel while leaving the metal behind for disposal.
[0039] In a more complex device for a much larger application, the
burner combustion would take place in a sloped rotary kiln, with
the combustible products as vapors or gases leaving the upper
opening and the metal waste discharging from the lower opening. The
metal would be then be recyclable as steel scrap.
[0040] In either case the metal scrap would be condensed and much
more easily handled then the wire that is currently generated when
processing scrap tires. The cost would be much lower also when
compared to conventional scrap tire processing with de-wiring and
separation of the rubber from the metal. The inherent problems in
the use of tires as fuel and the separation of the metal from the
rubber are thus solved and the rubber can be burned for additional
fuel while also allowing the scrap metal from the tires to be
reused in a desired format.
[0041] It is contemplated that the inventive concepts herein
described may be variously otherwise embodied and it is intended
that the appended claims be construed to include alternative
embodiments of the invention except insofar as limited by the prior
art. For example, various types of furnaces may be used with the
present invention, and the scrap tires may be of different types.
Furthermore, different types of metals may be melted in the furnace
besides the scrap metal, including such metals as iron pellets,
direct reduced iron ("DRI"), pig iron and iron carbide, which are
often scrap substitutes.
[0042] There has therefore been shown and described a process for
melting scrap metal which accomplishes the stated objectives.
* * * * *