US20020011132A1 - Process to preheat and carburate directly reduced iron (DRI) to be fed to an electric arc furnace (EAF) - Google Patents
Process to preheat and carburate directly reduced iron (DRI) to be fed to an electric arc furnace (EAF) Download PDFInfo
- Publication number
- US20020011132A1 US20020011132A1 US09/836,062 US83606201A US2002011132A1 US 20020011132 A1 US20020011132 A1 US 20020011132A1 US 83606201 A US83606201 A US 83606201A US 2002011132 A1 US2002011132 A1 US 2002011132A1
- Authority
- US
- United States
- Prior art keywords
- gas
- melting furnace
- dri
- process according
- temperature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000000034 method Methods 0.000 title claims abstract description 39
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 22
- 238000010891 electric arc Methods 0.000 title claims description 5
- 238000002844 melting Methods 0.000 claims abstract description 59
- 230000008018 melting Effects 0.000 claims abstract description 59
- 239000007789 gas Substances 0.000 claims description 128
- 239000000203 mixture Substances 0.000 claims description 26
- 238000002485 combustion reaction Methods 0.000 claims description 19
- 239000003517 fume Substances 0.000 claims description 12
- 238000006243 chemical reaction Methods 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 229910000831 Steel Inorganic materials 0.000 claims description 8
- 238000001816 cooling Methods 0.000 claims description 8
- 238000007599 discharging Methods 0.000 claims description 8
- 239000010959 steel Substances 0.000 claims description 8
- 238000012432 intermediate storage Methods 0.000 claims description 4
- 238000010309 melting process Methods 0.000 abstract description 8
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 15
- 238000006722 reduction reaction Methods 0.000 description 11
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 8
- 238000007254 oxidation reaction Methods 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000011282 treatment Methods 0.000 description 4
- 238000010744 Boudouard reaction Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 230000036961 partial effect Effects 0.000 description 3
- 238000010405 reoxidation reaction Methods 0.000 description 3
- 238000003723 Smelting Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 230000001174 ascending effect Effects 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000002801 charged material Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 229910001608 iron mineral Inorganic materials 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000036963 noncompetitive effect Effects 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/14—Multi-stage processes processes carried out in different vessels or furnaces
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0086—Conditioning, transformation of reduced iron ores
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/52—Manufacture of steel in electric furnaces
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/10—Reduction of greenhouse gas [GHG] emissions
- Y02P10/134—Reduction of greenhouse gas [GHG] emissions by avoiding CO2, e.g. using hydrogen
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Definitions
- the present invention relates to a high energy-saving process for preheating and carburation of directly reduced iron (DRI) to be conveyed to a melting process, by using melting furnace off-gas, which is characterized by a high temperature and a high CO-content.
- DRI directly reduced iron
- steel can be produced from iron ores/iron minerals by direct reduction of the solid iron ore to produce sponge iron (“directly reduced iron”, DRI).
- This DRI is then fed to a melting furnace or a smelting furnace, for example, an electric arc furnace (EAF), or the like.
- EAF electric arc furnace
- heat can be transferred from a gas to an object through two different ways.
- heat can be transferred via the sensitive power/heat of a gas, which corresponds to its temperature, flow rate and composition.
- Another method that allows some energy saving in the melting process consists in preheating the EAF feeding (i.e. the DRI) by means of the sensitive heat of the gases coming out of the melting process.
- EAF feeding i.e. the DRI
- DRI the sensitive heat of the gases coming out of the melting process.
- U.S. Pat. No. 4,736,383, WO 98/43032 U.S. Pat. No. 4,002,465, which is mainly used for scrap pre-heating and which is suitable for different plants.
- all these processes are associated with high emissions of CO 2 .
- the optimal theoretic C-content value is the one which facilitates or enables the reduction of the remaining FeO (wustite) during the melting process in the EAF, according to the following reaction:
- DRI directly reduced iron
- EAF electric arc furnace
- the process according to the present invention has the advantage that both the latent heat and the sensitive heat of the melting furnace off-gas are used to preheat the DRI. Further, due to the high CO-content of the melting furnace off-gas, natural gas for carburation of said DRI is saved and the addition of carbon in the melting furnace or the EAF can be avoided or at least considerably reduced.
- At least the temperature of the melting furnace off-gas is measured before adjusting the temperature and the composition of the melting furnace off-gas.
- At least the composition of the melting furnace off-gas is measured before adjusting the temperature and the composition of the melting furnace off-gas.
- the melting furnace is an electrical furnace (EAF).
- the temperature of the melting furnace off-gas is adjusted to ⁇ 800° C., preferably 450-800° C., and/or its composition to have a CO/CO 2 -ratio of at least 1, preferably 1-3.
- the upper limit of 800° C. is determined by the fact that usually the CO/CO 2 -ratio in the off-gas coming from the furnace is not over 5,5. This value corresponds to a temperature of 800° C. for the carburation zone (see FIG. 2A).
- the lower limits of 450° C. for T and 1,0 for the CO/CO 2 -ratio are determined by the fact that below these values no remarkable deposition of C is verified due to the kinetic of carburation.
- the adjustment of temperature and composition of the melting furnace off-gas is preferably performed by burning a mixture of air and/or O 2 , recycle gas obtained from gas which has been contacted with the DRI, and optionally CH 4 , with the melting furnace off-gas.
- the recycle gas is preferably obtained after removing fines, cooling the gas, pressurizing and intermediate storage of the gas.
- the DRI is preferably preheated to a temperature of 300-700° C. using the adjusted melting furnace off-gas.
- the use of melting furnace off-gas has the advantage that the melting furnace off-gas does not have to be transferred to a fume plant and wasted.
- the DRI is contacted with said adjusted gas by a vertically split flow.
- the DRI is preferably carburated to a C-content of 0-3 wt-%.
- the addition of carbon in the melting furnace or EAF can be avoided or at least considerably reduced.
- the adjusted gas contains 0-30% H 2 which is produced by the reaction of CH 4 with O 2 .
- H 2 has the advantage that the reducing capability of the atmosphere used to preheat the DRI is increased, which prevents Fe in the DRI from being (re)oxidized to FeO and/or helps to reduce residual FeO in the DRI to Fe.
- the present invention also comprises a plant for performing the process according to claim 1 .
- the plant for performing the process of the present invention comprises a means for measuring at least the temperature of the melting furnace off-gas and/or the composition of the melting furnace off-gas.
- This means is preferably a combustion chamber.
- the adjustment of the melting furnace off-gas is preferably performed in a combustion chamber, comprising a controlled burner, controlled inlets for melting furnace off-gas, CH 4 , air and/or O 2 and cooling recycled gas and a controlled outlet for transferring said adjusted gas to the preheater.
- the plant further comprises a device for separating fines from the preheater off-gas, a cooling device for cooling the preheater off-gas, a pressurizing device and an intermediate storage device, from which the recycled preheater off-gas is transferable to the combustion chamber and/or a fume plant.
- the preheater off-gas can be advantageously recycled and used to cool the melting furnace off-gas.
- the preheater comprises preferably at least one discharging device at the bottom and at least one gas inlet for the gas to be contacted with the DRI.
- the preheater has essentially a cylindrical form.
- the preheater comprises at least two conical discharging devices located at the bottom of said cylindrical container and three gas inlets for the gas to be contacted with the DRI, wherein one gas inlet is located centrally at the bottom of the preheater and two gas inlets are located at the side of said conical discharging devices.
- FIG. 1 shows the thermodynamic flow of the Boudouard reaction as a function of the temperature for a feeding gas characterized by a CO/CO 2 -ratio of 2 at a temperature of 750° C. or higher.
- FIG. 2B shows the thermodynamic conditions for reduction and carburation in the presence of 20% (CO+CO 2 ).
- FIG. 3 shows a plant for preheating and carburation of DRI to be fed to an EAF.
- FIG. 4 is an enlarged view of the preheater of FIG. 3.
- FIG. 5 shows a side view of the preheater and sectional views indicating the positions of gas inlets.
- the present invention describes a procedure which permits to preheat and carburate DRI using the off-gas of the melting process, usually performed in an EAF. According to this process, the energy consumption in the production of liquid steel can be considerably reduced in different ways:
- Carburation can be carried out in a preheating reactor thanks to the exothermic Boudouard reaction (2CO C+CO 2 ) which is catalysed by Fe and whose thermodynamic flow is shown in FIG. 1 for a gas having a CO/CO 2 -ratio of 2 at a temperature of 750° C. or higher.
- the C deposit reaction is favoured by low temperatures (exothermic reaction), it does not show a remarkable reaction rate for T ⁇ 400-500° C.
- the composition of the gas fed to the preheating reactor and its temperature should be defined in order to avoid the Fe reoxidation reaction and, if possible, to favour the reduction of remaining FeO present in the DRI.
- FIG. 2A a thermodynamic diagram is shown, which gives the min. value of the CO/CO 2 -ratio to be present in the gas to heat the DRI without incurring in its reoxidation.
- the limit conditions are also summarized in Table 1.
- the components of the off-gases are in this case only CO and CO 2 .
- off-gases are composed of CO, CO 2 and other components, i.e. N 2 , H 2 , H 2 O.
- the C+CO 2 2CO equilibrium curve moves towards left (see FIG.
- the melting furnace off-gas composition will usually be adjusted using recycle gas, CH 4 and O 2 and/or air, it is also possible according to the present invention to use the melting furnace off-gas without a subsequent adjustment of its composition.
- the off-gas of the melting process is preferably conveyed into a combustion chamber where, after mixing with recycle gas and, if necessary, with CH 4 and O 2 and/or air (in order to increase the CO/CO 2 ratio), a reducing gas with desired temperature and composition is generated.
- Cold fed DRI can be preheated, depending on the gas used, up to a temperature of 300-700° C. In this case, the preheating is to a large extent achieved by the heat generated by the exothermic carburation reaction.
- the upper limit of the DRI preheating temperature depends on the characteristics of the processed material, but may be limited by the following considerations:
- 2CO C+CO 2 may be (re)gasified.
- Preferred operative ranges to obtain preheating and carburation are:
- the DRI is preheated to a temperature of 300 to 700° C.
- a suitable plant according to the present invention should focus on the possibility of carburation and preheating DRI using melting furnace off-gases, preferably EAF off-gases, which otherwise would directly flow to the fume plant.
- the sensitive heat of fumes with a rich carbon monoxide content is used, in addition with the heat produced by their combustion with air or an air/O 2 -Mixture in a chamber capable of burning such fumes in a controlled manner.
- CH 4 and O 2 can be injected in the combustion chamber in order to increase the CO/CO 2 -ratio and to obtain a reducing atmosphere through the reaction of partial CH 4 oxidation to yield CO and H 2 .
- the gases coming from the preheater are directly conveyed to the fume plant.
- the temperature of the off-gases flowing to the preheater may be controlled, for instance, using a heat exchanger.
- the plant is equipped with instruments for measuring the temperature and the composition of the melting furnace off-gas.
- the range of flow rates of the adjusted off-gas to be fed to the preheater is very wide.
- the lower value is the theoretic value required for the carburation and preheating of the DRI.
- the maximum value depends on the pressure drop in the preheater and on the stability of the material inside the preheater. Flow rates range from about 300 to about 2,500 Nm 3 /t.
- a plant in accordance with the present invention is shown schematically in FIG. 3.
- the plant includes an EAF (1), capable of melting DRI for the production of liquid steel.
- the secondary product of the melting operation (EAF off-gas) is the off-gas of the decarburation phase. Since it is mainly made of CO, it can bum and produce the heat necessary to preheat the DRI.
- This off-gas leaving the EAF with a temperature of about 1200° C. to about 1600° C. enters the combustion chamber (2), where it is oxidised with air (air/O 2 ) in an atmosphere thermally controlled by the recycle gas according to a ratio, which permits to obtain fumes at a temperature of ⁇ 800° C. and a CO/CO 2 -ratio of 1-3.
- air air/O 2
- CH 4 and ° 2 can be injected in the combustion chamber in order to increase the CO/CO 2 -ratio and to obtain a reducing atmosphere through the reaction of partial CH 4 oxidation to yield CO and H 2 .
- the H 2 -content can vary between 0 to about 30%.
- the preheater ( 3 ) can be seen as a shaft for inside refractory preheating and is equipped with a tapered discharging device at the bottom for the descent of the solid material once the heating has concluded. While ascending, the adjusted melting furnace off-gas transfers its heat to the DRI which is loaded in solid form at ambient temperature prior to the preheating by means of a charging system, and leaves the preheater through a collector located at the upper side of the preheater ( 3 ). Afterwards, the gases pass to the operations of removement of the fines and a dust separator ( 4 ) (cyclone and scrubber) and are subsequently cooled by means of a heat exchanger ( 5 ). The gas temperature reached at the end of these treatments allows using a fan ( 6 ) capable of adjusting the pressure back to the values approximating the ones present in the combustion chamber. The fan performance does not exceed 600-800 mm H 2 O.
- the off-gas of the storage unit ( 7 ) is split by a three-line valve, regulated by controlling the temperature of the products of the fume partial combustion of chamber ( 2 ), which divides the off-gas into two independent flows: the first one is directed to the combustion chamber, the second one is destined to the exhaust gas treatment plant.
- the preheater which is shown in FIG. 4, is not very high and has a considerable horizontal extension. Thus, a specific gas distribution is required to homogeneously contact all the charged material mass.
- the heating gas is injected through two distinct ways: the first one consisting in an injection between the two discharge cones at the bottom of the cylindrical area ( 8 ), the second one through two distribution rings placed at the top of the two discharge cones ( 9 ).
- FIG. 5 sectional views of the preheater are shown, indicating the positions of the gas inlets.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Furnace Details (AREA)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP00111036.0 | 2000-05-31 | ||
| EP00111036A EP1160337A1 (fr) | 2000-05-31 | 2000-05-31 | Procédé pour préchauffer et carburer du fer directement réduit avant de le transférer à un four à arc |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US20020011132A1 true US20020011132A1 (en) | 2002-01-31 |
Family
ID=8168812
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US09/836,062 Abandoned US20020011132A1 (en) | 2000-05-31 | 2001-04-17 | Process to preheat and carburate directly reduced iron (DRI) to be fed to an electric arc furnace (EAF) |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US20020011132A1 (fr) |
| EP (1) | EP1160337A1 (fr) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080182215A1 (en) * | 2007-01-31 | 2008-07-31 | Alberto Sid | System and method for controlling toxic gas |
| US20100058892A1 (en) * | 2006-01-04 | 2010-03-11 | Karl Brotzmann | Method for Preheating Iron Agglomerates |
| US20210301360A1 (en) * | 2020-03-24 | 2021-09-30 | Midrex Technologies, Inc. | Method and system for heating direct reduced iron (dri) between a dri source and processing equipment for the dri |
| US11427877B2 (en) | 2017-09-21 | 2022-08-30 | Nucor Corporation | Direct reduced iron (DRI) heat treatment, products formed therefrom, and use thereof |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2385947C2 (ru) * | 2006-01-04 | 2010-04-10 | Саршталь Аг | Способ предварительного разогрева металлизированных окатышей или брикетов |
| KR20150063075A (ko) * | 2012-09-14 | 2015-06-08 | 뵈스트알파인 스탈 게엠베하 | 제강 방법 |
| DE102020205493A1 (de) | 2020-04-30 | 2021-11-04 | Sms Group Gmbh | Verfahren zum Herstellen von flüssigem Roheisen aus einem DRI-Produkt |
| WO2024170464A1 (fr) | 2023-02-14 | 2024-08-22 | Tata Steel Ijmuiden B.V. | Procédé de production de fer préréduit |
| WO2025219324A1 (fr) | 2024-04-17 | 2025-10-23 | Tata Steel Nederland Technology B.V. | Procédé de production de fer de réduction directe comprenant du carbone intégré |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1038230B (it) * | 1974-05-22 | 1979-11-20 | Krupp Gmbh | Procedimento per la produzione di acciaio |
| US4053301A (en) * | 1975-10-14 | 1977-10-11 | Hazen Research, Inc. | Process for the direct production of steel |
| US4111687A (en) * | 1976-11-01 | 1978-09-05 | Consolidated Natural Gas Service Company, Inc. | Process for the production of intermediate hot metal |
| WO1992002824A1 (fr) * | 1990-08-01 | 1992-02-20 | Iron Carbide Holdings, Limited | Procede de commande de la conversion de la charge d'un reacteur contenant du fer en carbure de fer |
-
2000
- 2000-05-31 EP EP00111036A patent/EP1160337A1/fr not_active Withdrawn
-
2001
- 2001-04-17 US US09/836,062 patent/US20020011132A1/en not_active Abandoned
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100058892A1 (en) * | 2006-01-04 | 2010-03-11 | Karl Brotzmann | Method for Preheating Iron Agglomerates |
| US9200338B2 (en) * | 2006-01-04 | 2015-12-01 | Saarstahl Ag | Method for preheating iron agglomerates |
| US20080182215A1 (en) * | 2007-01-31 | 2008-07-31 | Alberto Sid | System and method for controlling toxic gas |
| US8286603B2 (en) | 2007-01-31 | 2012-10-16 | Fumes Safety Llc | System and method for controlling toxic gas |
| US11427877B2 (en) | 2017-09-21 | 2022-08-30 | Nucor Corporation | Direct reduced iron (DRI) heat treatment, products formed therefrom, and use thereof |
| US20210301360A1 (en) * | 2020-03-24 | 2021-09-30 | Midrex Technologies, Inc. | Method and system for heating direct reduced iron (dri) between a dri source and processing equipment for the dri |
| US11965221B2 (en) * | 2020-03-24 | 2024-04-23 | Midrex Technologies, Inc. | Method and system for heating direct reduced iron (DRI) between a DRI source and processing equipment for the DRI |
Also Published As
| Publication number | Publication date |
|---|---|
| EP1160337A1 (fr) | 2001-12-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| AS | Assignment |
Owner name: DANIELI & C., ITALY Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:PAVLICEVIC, MILORAD;BURBA, GIANNI;PRIMAVERA, ALESSANDRA;AND OTHERS;REEL/FRAME:011957/0148 Effective date: 20010629 |
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| STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |