CA1110454A - Method and apparatus for reducing particulate iron oxide to molten iron with solid reductant - Google Patents
Method and apparatus for reducing particulate iron oxide to molten iron with solid reductantInfo
- Publication number
- CA1110454A CA1110454A CA322,944A CA322944A CA1110454A CA 1110454 A CA1110454 A CA 1110454A CA 322944 A CA322944 A CA 322944A CA 1110454 A CA1110454 A CA 1110454A
- Authority
- CA
- Canada
- Prior art keywords
- furnace
- burden
- top gas
- electrode
- gas
- 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.)
- Expired
Links
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 61
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 title claims abstract description 34
- 238000000034 method Methods 0.000 title claims abstract description 29
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 27
- 239000007787 solid Substances 0.000 title claims abstract description 14
- 239000003638 chemical reducing agent Substances 0.000 title claims abstract description 9
- 239000000446 fuel Substances 0.000 claims abstract description 13
- 238000010438 heat treatment Methods 0.000 claims abstract description 7
- 239000000203 mixture Substances 0.000 claims abstract description 3
- 239000007789 gas Substances 0.000 claims description 76
- 239000000463 material Substances 0.000 claims description 18
- 239000010802 sludge Substances 0.000 claims description 10
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 9
- 238000004140 cleaning Methods 0.000 claims description 9
- 239000003245 coal Substances 0.000 claims description 9
- 229910052760 oxygen Inorganic materials 0.000 claims description 9
- 239000001301 oxygen Substances 0.000 claims description 9
- 238000001816 cooling Methods 0.000 claims description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 7
- 229910052799 carbon Inorganic materials 0.000 claims description 7
- 229910052751 metal Inorganic materials 0.000 claims description 7
- 239000002184 metal Substances 0.000 claims description 7
- 235000019738 Limestone Nutrition 0.000 claims description 6
- 239000006028 limestone Substances 0.000 claims description 6
- 239000002893 slag Substances 0.000 claims description 5
- 239000000956 alloy Substances 0.000 claims description 4
- 229910045601 alloy Inorganic materials 0.000 claims description 4
- 239000000571 coke Substances 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 4
- 230000003134 recirculating effect Effects 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- 239000010459 dolomite Substances 0.000 claims description 3
- 229910000514 dolomite Inorganic materials 0.000 claims description 3
- 239000003077 lignite Substances 0.000 claims description 2
- 239000007795 chemical reaction product Substances 0.000 claims 1
- 239000000047 product Substances 0.000 claims 1
- 238000013022 venting Methods 0.000 claims 1
- 239000008188 pellet Substances 0.000 abstract description 13
- 239000004449 solid propellant Substances 0.000 abstract description 8
- 238000002844 melting Methods 0.000 abstract description 3
- 230000008018 melting Effects 0.000 abstract description 3
- 238000006243 chemical reaction Methods 0.000 description 6
- 238000001465 metallisation Methods 0.000 description 6
- 239000003921 oil Substances 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 238000009628 steelmaking Methods 0.000 description 4
- 239000011269 tar Substances 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- 238000010891 electric arc Methods 0.000 description 3
- 239000003039 volatile agent Substances 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910000805 Pig iron Inorganic materials 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 239000002802 bituminous coal Substances 0.000 description 1
- 150000001721 carbon Chemical class 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 238000005255 carburizing Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 238000004858 feed analysis Methods 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 235000011837 pasties Nutrition 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
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
- C21B13/02—Making spongy iron or liquid steel, by direct processes in shaft furnaces
- C21B13/023—Making spongy iron or liquid steel, by direct processes in shaft furnaces wherein iron or steel is obtained in a molten state
- C21B13/026—Making spongy iron or liquid steel, by direct processes in shaft furnaces wherein iron or steel is obtained in a molten state heated electrically
-
- 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
Abstract
ABSTRACT OF THE DISCLOSURE
A method and apparatus for reducing particulate iron oxide to molten iron utilizing solid carbonaceous fuel as reductant in a shaft type reducing furnace, in which a furnace burden is formed of a mixture of iron oxide lumps or pellets and particulate solid fuel. Reacted top gas is upgraded and recirculated through the burden in counter-flow relationship thereby heating, reducing and melting the burden. The heat for reduction and melting is generated by passing electric current through the burden.
A method and apparatus for reducing particulate iron oxide to molten iron utilizing solid carbonaceous fuel as reductant in a shaft type reducing furnace, in which a furnace burden is formed of a mixture of iron oxide lumps or pellets and particulate solid fuel. Reacted top gas is upgraded and recirculated through the burden in counter-flow relationship thereby heating, reducing and melting the burden. The heat for reduction and melting is generated by passing electric current through the burden.
Description
5~
BACKGROUND OF TffE INVENTION
In recent years the direc~ reduction of iron oxide to metallic iron has become a practical con~nercial reality with increasing worldwide acceptance and production, The direct reduced iron which results from direct reduction of iron oxide has a commercially demonstrated utility ;n iron and steelmaking and p~rticularly in electric arc furnace steelmakin~, Direct reduced iron, which is sometimes known as sponge iron, is not suited as the principal feed ma.erial for steelmaking furnaces other than electric arc furnaces, Other steelmaking processes such as the basic oxygen pr cess and the bottom blown oxygen process require Isrge quantities of ~".''' .
hot metal, or molten metal as feed material. Thus, for oxygen furnace feed, it is desired to produce a molten product from a direct reduction furnace.
A known type process gasifies solid fuel in a separate combustion-type gasifier utilizing oxygen and steam for gasification. The gas from the gasifier is then cooled and scrubbed, desulfurized, then utilized in a direct reduction furnace as the source of reductant. An example of this combination of gasifier and direct reductisn furnace is described in U.S.
Patent No. 3,844,766. This combination also has a fundamental thermal disadvantage in that approximately 50 percent of the solid -fuel is consumed tO by combustion in the gasifier and only the remaining 50 percent of the fuel value is available as a source of reductant. This combination, although hlghly efftcient In the use o-F the gas -From the gasiFier for reduct;on, requires approxlmately 4.0 to 5.0 Glga calories of solid fuel per metric l ton of solid direct reduced iron product.
l An electrically operated vertical shaft furnace is taught by U.S, ¦ Patent No. 1,937,064 in which broken coke, graphite, silicon carbide or other ¦ conductors are charged to form a burden. Molten metal is then poured through ¦ the burden while electrical current also flows through the burden, thus ¦ refining the molten metal. The burden is a stationary granular mass of 2û ¦ carbonaceous material which does not flow through the furnace. The burden also Ts not the material being treated, unlike the present invention.
l Langhammer U.S. Patent No. 3,894,864 purports to teach a shaft furnace ¦ for producing molten steel by use of an electric arc. The patent fails ¦ to explain the completion of the electric circuit which creates the electric
BACKGROUND OF TffE INVENTION
In recent years the direc~ reduction of iron oxide to metallic iron has become a practical con~nercial reality with increasing worldwide acceptance and production, The direct reduced iron which results from direct reduction of iron oxide has a commercially demonstrated utility ;n iron and steelmaking and p~rticularly in electric arc furnace steelmakin~, Direct reduced iron, which is sometimes known as sponge iron, is not suited as the principal feed ma.erial for steelmaking furnaces other than electric arc furnaces, Other steelmaking processes such as the basic oxygen pr cess and the bottom blown oxygen process require Isrge quantities of ~".''' .
hot metal, or molten metal as feed material. Thus, for oxygen furnace feed, it is desired to produce a molten product from a direct reduction furnace.
A known type process gasifies solid fuel in a separate combustion-type gasifier utilizing oxygen and steam for gasification. The gas from the gasifier is then cooled and scrubbed, desulfurized, then utilized in a direct reduction furnace as the source of reductant. An example of this combination of gasifier and direct reductisn furnace is described in U.S.
Patent No. 3,844,766. This combination also has a fundamental thermal disadvantage in that approximately 50 percent of the solid -fuel is consumed tO by combustion in the gasifier and only the remaining 50 percent of the fuel value is available as a source of reductant. This combination, although hlghly efftcient In the use o-F the gas -From the gasiFier for reduct;on, requires approxlmately 4.0 to 5.0 Glga calories of solid fuel per metric l ton of solid direct reduced iron product.
l An electrically operated vertical shaft furnace is taught by U.S, ¦ Patent No. 1,937,064 in which broken coke, graphite, silicon carbide or other ¦ conductors are charged to form a burden. Molten metal is then poured through ¦ the burden while electrical current also flows through the burden, thus ¦ refining the molten metal. The burden is a stationary granular mass of 2û ¦ carbonaceous material which does not flow through the furnace. The burden also Ts not the material being treated, unlike the present invention.
l Langhammer U.S. Patent No. 3,894,864 purports to teach a shaft furnace ¦ for producing molten steel by use of an electric arc. The patent fails ¦ to explain the completion of the electric circuit which creates the electric
2~ ¦ arc. Applicants distinguish from this process by utilizing direct resistance ¦ heating of their burden, unlike any known reference, as well as by recirculating spent top gas to act as reductant source.
Other patents which may be of interest to the reader include Elvander et al U,S, Patent No. 3,948,640 and Gross U.S, Patent No. 3,94~,642.
OBJECT OF THE INV~NTION
It is the principal object of the present in~ention to provide a method and apparatus .for directly reducing iron oxide to molten iron in a shaft type reduction furnace wherein solid fuel is utilized as the r~ductant source.
SUMMARY OF THE INVENTI ~N
The present invention is a direct reduction method utill~ing solid fuel in a novel and highly thermally efficient manner wherein the solid fuel is consumed directly in -the re-duction process by reaction with oxygen from the iron oxide which is being reduced. The overall reactions in -the furnace are endothermic, the heat required being supplied by elec-trically heating the burden. Exclusion of an external source of air or industrial ox~gen results in a solicl fuel requirem~nt oE approx-imately 2.2 Giya calories per metr.ic tOIl of direct recluced .iron product with an additional electric enc-~rgy requirement of approx-imately 700 kWh (0.6 Giga calories) per metric ton of direc-t reduced iron in the solid state, with an additional 200 kWh to further heat and melt the direct reduced iron and gangue.
As a specific embodiment of -the invention there is provided apparatus comprising: (a) a shaft furnace having a particle introducing means generally at tne top thereof for establishing a gravitationally descendin~ burden therein, a molten iron collection chamber at the bottom thereof, and molten iron removal means; (b) an electrode positioned within said chamber adapted to contact molten metal within said chamber, at least one second electrode positioned in said furnace above said chamber and adapted to contact the particulate burden in said furnace, including an e~ternal source o~ electric power for passing an electric current .through said burden; (c~ a gas outlet in the upper reg.ion of said furnace for removing reacted top gas; (d) means external to said furnace for cooling and cleaning removed top gas, said cooling and cleaning means communicatlng with said means ~or removinq -top cJas; ~e) means _ 3 _ ...
.. . .. :
communicating Wi th said top gas cooling and cleaning means and with the interior of said furnace for heating said cooled and cleaned top gas; and (f) means for introducing heated gas to said furnace in the lower region thereof.
a - ..
lllQ~54 BRIEF DESCRIPTION OF THE DRAWING
The present invention will be more readily understood by referring to the following detailed specification and the appended drawing in which:
The single figure is a schematic cross section of an elevational view of the shaft furnace of the present invention and related equipment.
DETAILED DESCRIPTION
Referring now to the drawing, a shaft type furnace 10 having a steel shel1 12 is lined with refractory 14. A feed hopper 16 is mounted at the top of furnace 10 for charging of particulate solids feed material 18 therein. The feed material consists o~ iron oxicle in the form of pellets or lumps, solid carbon~ceous fuel and limestone. The feed material descends by gravity through one or more feed pipes 20 to Form a packed bed 22 of particulate solids feed material or burden in the Furnace 10 Reduced molten product is removed from the furnace through taphole 24 If desired, a slag taphole 26 can be provided at a higher elevation. Removal of the molten iron and slag establishes a gravitational flow of the particulate burden 22 through shaft furnace 10.
The furnace 10 is preferably cylindrical but could have any desired cross-section The upper region of the furnace is provid~d with at least one heat res;stant alloy electrode 30, which extends through the steel furnace shell 12 and across the furnace width. This electrode may be fixed or journaled for rotation in bearings 32A and 328 which may ba mounted externally as shown, or insulated and mounted in the furnace walls 14. Each electrode rod may be equipped with one or more heat resistant alloy discs 35 to provide an axtended electrode surface area. The number oF electrode rods employed is dependent upon the horizontal dimensions of the furnace. The bottom of the shaft furnace is a closed hearth lined with carbon block 37, which enables the entire hearth to act as an electroae. This carbon block s~
hearth is connected to a source of electricity through electrode buss 38.
Suitable thermocouples such as 40A and 40B are inserted into the furnace through the refractory wall at selected elevations to assist in controlling the operation of the process.
Top gas exits the furnace through a top gas outlet pipe 44 located above stock line 46, The lower end of feed pipe 20 extends below outlet pipe 44, which arrangement creates a top gas disengaging plenum 48 which permits the top gas to exit generally symmetrically from the stock line 46 and flow freely to the top gas outlet pipe 44, A gas cleaning and recirculating circuit is provided to remove solids and condensible matter from the top gas and to cool the gas to form cold process gas, The reacted top gas leaving the shaft furnace lO through p7pe 44 flows to an oil scrubber 50 wherein tars, oils, and parttculates are removed from the gas as a sludge. Pump 52 pumps the sludge back to the furnace through sludge injection pipe 54 which has an open lower end extending well beneath the stock line 46 to insure reaction of sludge components with the burden and to prevent top gas from recycling these components back into the oil scrubber.
The top gas passes from the oil scrubber 50 to a water scrubber 60 wherein the gas Is further cooled and cleaned, A gas recirculating blower 62 draws the cooled and cleaned process gas from the scrubber 60. A portion of the process gas Is introduced to pipe 68 to asstst in 7njecting the sludge into the shaft furnace burden. Some process gas must normally be vented because when solid carbon in the furnace reacts with oxygen from the iron oxide, carbon monoxide gas and carbon dioxide gas ar6 formed, Since this react70n involves a gaseous expansion, excess gas may be vented through vent Vl. Of course, this excess gas provides a source of energy for use sewhere.
l ~ 5~
A second portion of the process gas passes through pipe 72 into gas _ preheater 74 wherein tha gas is heated to reducing temperature of about 900 to 1000C The heated gas flows through pipe 76 and is introduced to the furnace through hot process gas inlet 78 and bustle 80. Another portion of the process gas is fed into pipe 86 as fuel for preheater burner 90.
Combustion air from the burner 90 is provided by air source 92.
One or rrlore electrodes 30 are provided, depending upon the dimensions of the horizontal cross-section of the furnace. The electrode acts as a feeder mechanism as well as a cluster breaker for material in the upper zone of the furnace The electrode can carry one or more radially extending breaker segments 35 and can be connected to and driven by oscillatible drive mechanism 95. Each cluster breaker segment extends only about 180 to 270 degrees about the electrode, or it may extend completely around the electrode.
Thus, as the el~ctrode oscillates withln the bearlngs, it acts as both a feed mechanism and cluster breaker mer.hanism. It feeds material alternately by moving material downwardly from opposite walls of the furnace while simutaneously breaking any clusters of the hot cohesive material.
In the method of this invention, iron oxide pellets, lump ore or other suitable iron oxide feed material is mixed with solid carbonaceous fuel such 2Q as coal, coke, or lignite and limestone, then fed through feed pipe 20 to the interTor of the furnace lO to form burden 22 therein as a packed bed The furnace Is heated electro-thermally by passing electric current through the burden between the hearth electrode 37 and the upper alloy electrode 30 in the furnace. Directly reduced iron pellets or lumps are electrically conductive even at the earliest s~age of reduction when metallic iron is formed only on the pellet surface When starting up operation of the electric powered shaft furnace of the present invention, the furnace is charged with reduced or partially metallized directly reduced iron pellets, petroleum:coke or any other electrically conductive rnaterial.
~ O her C UCti e materials are utilized ~hen reduced or parl:ially metallized s~
pellets are available. It has been determined that pellets with metal-lizations as low as 6 percent are conductive.
The shaft furnace includes three distinct pr~cess zones. The upper region constitutes a prereduction zone in which the burden is heated by convection of gases moving in counter-flow relation to the flow of the burden. Coal or other carbonaceous fuel in the fePd liberates condensible and noncondensible volatiles. The noncondensible volatiles, which are mostly hydrogen or hydrocarbons, exit as top gas, are cleaned and recirculated as process gas. The pellet burden acts as a moving packed bed pebble quench which is very effective in preventing heavy liquid compounds from plugging gas outlet pipes. Some heavy oils and tars tend to weep out of the coal and are absorbed by the oxide feed to subsequently react with C02 and water vapor in the process gas. A high ratio of oxide Feed to heavy liquid compound~
reduces the tendency of the burden to cluster excessively near the burden stockline. In this prereduction zone, the oxide feed material is reduced to low metalli~ation, i.e. metallization less than 25 percent, by reaction with reductants H2 and C0 in the upwardly moving gases Thus the burden becomes electrically conductive before it leaves the prereduction zone.
The central region of the shaft Furnace constitutes a reduction zone in which metallic iron is formed by reaction o-f the char formed from the carbonaceous fuel with oxygen From the iron oxide. The reactions in the reduction zone are endothermic. The required heat in the reduction zone is supplied electro~thermally. This heat requirement ts approximately 700 kWh (0.8 Giga calories) per metric ton of direct reduced i-ron.
Excess heat in the reducing zone will cause the pellets to soften and the burden to become a pasty mass which will tend to prevent upflow of process gas through the burden or to curtail upflow of reducing gas The circulation of the process gas from bustle 80 through the burden will l help in maintaining the burden in solid particulate forrn until it reaches ehe melti g zone.
~ILlQ45~L
The lower region of the furnace constitutes a melting zone wherein the hot reduced pellets are melted prior to discharge. The additional heat requirement to ~elt the pellets is 200 kWh (about 0.17 Giga catories) per metric ton.
The product discharge from the shaft furnace is molten iron with about three to 12 percent impurities. The iron is converted to steel in an oxygen steelmaking furnace, or it can be used as pig iron A small amount, up to five weight percent, of limestone or dolomite may be added to the feed material to react with sulfur which may be liberated within the furnace This nonmetallic material can be separated from the molten iron product as slag or gangue An addltional amount of limestone or dolomite is ~dded to the Feed to fluidlze the slag in accordance with normal slagging practice.
As a specific example oF the operation of the furnace, calculations have been made regarding the gas flow rates, gas temperatures and gas compositions at a number of locations in the furnace flow diagram. These calculations have been based on an oxide feed analysis of 97 percent Fe203, with three percent gangue materials. Ten percent more coal than is theoretically required, having a proximate analysis of 57.6 percent fixed carbon, 3.3 percent water, 29.0 percent volatiles and 10 1 percent ash was used as a basis for these calculations. This is a high volatile grade A bituminous coal. The tar and oil yield from the coal is about 0 11 cubic meters per metric ton. Tars and oil present in the top gas are 22,000 milligrams per normal cubic meter. The temperature in the reducing zone is 980C. The metallization of the ultilnate product is 92 percent with the metallization taking place in the prereduction zone being 20 percent. The use of excess coal will result in carburizing the iron product.
~ LQ~5~L
Table 1 shows computed operating figures for a direct reduction furnace operated in accordance with the Tnvention, The gas analyses are typical operating figures at the locations indicated by the letter headings, These locations are as follows~
A, Top gas upon exit from top gas outlet 44, B. Gas exiting water-scrubber 60, C, Gas passing through vent Vl, D, Gas entering furnace inlet 78, E. Gas leaving the reduction zone, in the region of electrode 30.
Gas flows in the table are given in normal cubic meters per metric ton (Nm3/t) o~ Product.
~ Flow Nm3/t Prod,) ¦ 1300 1260 ~ 5 ~ 760 1280 Temp,-C 360 40 40 980 980 Analysis - %C0 49,t 50.7 50.7 53,9 65,6 %C2 23,3 24,1 24,1 20.9 8,3 %H2 17,0 17,6 17,6 14,4 21,0 %H20 9,0 6,0 6,o 9,2 4.5 %CH4 0,9 0,9 0,9 0,9 0,0 %N2 0,7 0,7 0.7 0,7 0,6 1 ~ 5~
Tests have been conducted to determine the electrical resistance at various temperatures of a packed bed burden consisting of 89 percent nominal 12 mm diameter pellets of approximately 90 percent metallization, lO percent nominal 12 mm diameter coal char from low volatile bitiminous coal and one percent limestone of nominal six mm diameter. In Table ll the resistivity represents the resistance through a burden having a face area one meter square and a resistance path depth of one meter. The table represents points taken from a curve of plotted data points:
TABLE II
Resistivity in Temperature Ohm-Meters 100C .0055 300C .0033 500C .0020 700C .Oû12 900C .0007 The preferred reduction temperature in the furnace of the present invention is in the range of 900 to 1000C, The burden resistivity in this temperature range at either low or high metallizations requires relatively high current at relatively low voltage wh;ch makes practical the resistance heating of the burden without need for sophisticated electrical insulation or grounding means.
S~MMARY OF THE ACHIEVEMENTS OF THE OBJECTS OF THE INVENTION
It is clear frorn the above that we have invented a method and apparatus for directly reducing iron oxide to molten iron in a shaft type reduction furnace utilizing solid fuel as the reductant source in which energy input requirements are greatly reduced over present cornmercial direct reduction plants and w h more efficient operat'on than was heretofore possible, 3L~ 5~
It is to be understood that the foregoing description and specific example are merely illustrative of the principles of the invention and that various modifications and additions may be made thereto by those skilled in the art without departing from the spirit and scope of the invention
Other patents which may be of interest to the reader include Elvander et al U,S, Patent No. 3,948,640 and Gross U.S, Patent No. 3,94~,642.
OBJECT OF THE INV~NTION
It is the principal object of the present in~ention to provide a method and apparatus .for directly reducing iron oxide to molten iron in a shaft type reduction furnace wherein solid fuel is utilized as the r~ductant source.
SUMMARY OF THE INVENTI ~N
The present invention is a direct reduction method utill~ing solid fuel in a novel and highly thermally efficient manner wherein the solid fuel is consumed directly in -the re-duction process by reaction with oxygen from the iron oxide which is being reduced. The overall reactions in -the furnace are endothermic, the heat required being supplied by elec-trically heating the burden. Exclusion of an external source of air or industrial ox~gen results in a solicl fuel requirem~nt oE approx-imately 2.2 Giya calories per metr.ic tOIl of direct recluced .iron product with an additional electric enc-~rgy requirement of approx-imately 700 kWh (0.6 Giga calories) per metric ton of direc-t reduced iron in the solid state, with an additional 200 kWh to further heat and melt the direct reduced iron and gangue.
As a specific embodiment of -the invention there is provided apparatus comprising: (a) a shaft furnace having a particle introducing means generally at tne top thereof for establishing a gravitationally descendin~ burden therein, a molten iron collection chamber at the bottom thereof, and molten iron removal means; (b) an electrode positioned within said chamber adapted to contact molten metal within said chamber, at least one second electrode positioned in said furnace above said chamber and adapted to contact the particulate burden in said furnace, including an e~ternal source o~ electric power for passing an electric current .through said burden; (c~ a gas outlet in the upper reg.ion of said furnace for removing reacted top gas; (d) means external to said furnace for cooling and cleaning removed top gas, said cooling and cleaning means communicatlng with said means ~or removinq -top cJas; ~e) means _ 3 _ ...
.. . .. :
communicating Wi th said top gas cooling and cleaning means and with the interior of said furnace for heating said cooled and cleaned top gas; and (f) means for introducing heated gas to said furnace in the lower region thereof.
a - ..
lllQ~54 BRIEF DESCRIPTION OF THE DRAWING
The present invention will be more readily understood by referring to the following detailed specification and the appended drawing in which:
The single figure is a schematic cross section of an elevational view of the shaft furnace of the present invention and related equipment.
DETAILED DESCRIPTION
Referring now to the drawing, a shaft type furnace 10 having a steel shel1 12 is lined with refractory 14. A feed hopper 16 is mounted at the top of furnace 10 for charging of particulate solids feed material 18 therein. The feed material consists o~ iron oxicle in the form of pellets or lumps, solid carbon~ceous fuel and limestone. The feed material descends by gravity through one or more feed pipes 20 to Form a packed bed 22 of particulate solids feed material or burden in the Furnace 10 Reduced molten product is removed from the furnace through taphole 24 If desired, a slag taphole 26 can be provided at a higher elevation. Removal of the molten iron and slag establishes a gravitational flow of the particulate burden 22 through shaft furnace 10.
The furnace 10 is preferably cylindrical but could have any desired cross-section The upper region of the furnace is provid~d with at least one heat res;stant alloy electrode 30, which extends through the steel furnace shell 12 and across the furnace width. This electrode may be fixed or journaled for rotation in bearings 32A and 328 which may ba mounted externally as shown, or insulated and mounted in the furnace walls 14. Each electrode rod may be equipped with one or more heat resistant alloy discs 35 to provide an axtended electrode surface area. The number oF electrode rods employed is dependent upon the horizontal dimensions of the furnace. The bottom of the shaft furnace is a closed hearth lined with carbon block 37, which enables the entire hearth to act as an electroae. This carbon block s~
hearth is connected to a source of electricity through electrode buss 38.
Suitable thermocouples such as 40A and 40B are inserted into the furnace through the refractory wall at selected elevations to assist in controlling the operation of the process.
Top gas exits the furnace through a top gas outlet pipe 44 located above stock line 46, The lower end of feed pipe 20 extends below outlet pipe 44, which arrangement creates a top gas disengaging plenum 48 which permits the top gas to exit generally symmetrically from the stock line 46 and flow freely to the top gas outlet pipe 44, A gas cleaning and recirculating circuit is provided to remove solids and condensible matter from the top gas and to cool the gas to form cold process gas, The reacted top gas leaving the shaft furnace lO through p7pe 44 flows to an oil scrubber 50 wherein tars, oils, and parttculates are removed from the gas as a sludge. Pump 52 pumps the sludge back to the furnace through sludge injection pipe 54 which has an open lower end extending well beneath the stock line 46 to insure reaction of sludge components with the burden and to prevent top gas from recycling these components back into the oil scrubber.
The top gas passes from the oil scrubber 50 to a water scrubber 60 wherein the gas Is further cooled and cleaned, A gas recirculating blower 62 draws the cooled and cleaned process gas from the scrubber 60. A portion of the process gas Is introduced to pipe 68 to asstst in 7njecting the sludge into the shaft furnace burden. Some process gas must normally be vented because when solid carbon in the furnace reacts with oxygen from the iron oxide, carbon monoxide gas and carbon dioxide gas ar6 formed, Since this react70n involves a gaseous expansion, excess gas may be vented through vent Vl. Of course, this excess gas provides a source of energy for use sewhere.
l ~ 5~
A second portion of the process gas passes through pipe 72 into gas _ preheater 74 wherein tha gas is heated to reducing temperature of about 900 to 1000C The heated gas flows through pipe 76 and is introduced to the furnace through hot process gas inlet 78 and bustle 80. Another portion of the process gas is fed into pipe 86 as fuel for preheater burner 90.
Combustion air from the burner 90 is provided by air source 92.
One or rrlore electrodes 30 are provided, depending upon the dimensions of the horizontal cross-section of the furnace. The electrode acts as a feeder mechanism as well as a cluster breaker for material in the upper zone of the furnace The electrode can carry one or more radially extending breaker segments 35 and can be connected to and driven by oscillatible drive mechanism 95. Each cluster breaker segment extends only about 180 to 270 degrees about the electrode, or it may extend completely around the electrode.
Thus, as the el~ctrode oscillates withln the bearlngs, it acts as both a feed mechanism and cluster breaker mer.hanism. It feeds material alternately by moving material downwardly from opposite walls of the furnace while simutaneously breaking any clusters of the hot cohesive material.
In the method of this invention, iron oxide pellets, lump ore or other suitable iron oxide feed material is mixed with solid carbonaceous fuel such 2Q as coal, coke, or lignite and limestone, then fed through feed pipe 20 to the interTor of the furnace lO to form burden 22 therein as a packed bed The furnace Is heated electro-thermally by passing electric current through the burden between the hearth electrode 37 and the upper alloy electrode 30 in the furnace. Directly reduced iron pellets or lumps are electrically conductive even at the earliest s~age of reduction when metallic iron is formed only on the pellet surface When starting up operation of the electric powered shaft furnace of the present invention, the furnace is charged with reduced or partially metallized directly reduced iron pellets, petroleum:coke or any other electrically conductive rnaterial.
~ O her C UCti e materials are utilized ~hen reduced or parl:ially metallized s~
pellets are available. It has been determined that pellets with metal-lizations as low as 6 percent are conductive.
The shaft furnace includes three distinct pr~cess zones. The upper region constitutes a prereduction zone in which the burden is heated by convection of gases moving in counter-flow relation to the flow of the burden. Coal or other carbonaceous fuel in the fePd liberates condensible and noncondensible volatiles. The noncondensible volatiles, which are mostly hydrogen or hydrocarbons, exit as top gas, are cleaned and recirculated as process gas. The pellet burden acts as a moving packed bed pebble quench which is very effective in preventing heavy liquid compounds from plugging gas outlet pipes. Some heavy oils and tars tend to weep out of the coal and are absorbed by the oxide feed to subsequently react with C02 and water vapor in the process gas. A high ratio of oxide Feed to heavy liquid compound~
reduces the tendency of the burden to cluster excessively near the burden stockline. In this prereduction zone, the oxide feed material is reduced to low metalli~ation, i.e. metallization less than 25 percent, by reaction with reductants H2 and C0 in the upwardly moving gases Thus the burden becomes electrically conductive before it leaves the prereduction zone.
The central region of the shaft Furnace constitutes a reduction zone in which metallic iron is formed by reaction o-f the char formed from the carbonaceous fuel with oxygen From the iron oxide. The reactions in the reduction zone are endothermic. The required heat in the reduction zone is supplied electro~thermally. This heat requirement ts approximately 700 kWh (0.8 Giga calories) per metric ton of direct reduced i-ron.
Excess heat in the reducing zone will cause the pellets to soften and the burden to become a pasty mass which will tend to prevent upflow of process gas through the burden or to curtail upflow of reducing gas The circulation of the process gas from bustle 80 through the burden will l help in maintaining the burden in solid particulate forrn until it reaches ehe melti g zone.
~ILlQ45~L
The lower region of the furnace constitutes a melting zone wherein the hot reduced pellets are melted prior to discharge. The additional heat requirement to ~elt the pellets is 200 kWh (about 0.17 Giga catories) per metric ton.
The product discharge from the shaft furnace is molten iron with about three to 12 percent impurities. The iron is converted to steel in an oxygen steelmaking furnace, or it can be used as pig iron A small amount, up to five weight percent, of limestone or dolomite may be added to the feed material to react with sulfur which may be liberated within the furnace This nonmetallic material can be separated from the molten iron product as slag or gangue An addltional amount of limestone or dolomite is ~dded to the Feed to fluidlze the slag in accordance with normal slagging practice.
As a specific example oF the operation of the furnace, calculations have been made regarding the gas flow rates, gas temperatures and gas compositions at a number of locations in the furnace flow diagram. These calculations have been based on an oxide feed analysis of 97 percent Fe203, with three percent gangue materials. Ten percent more coal than is theoretically required, having a proximate analysis of 57.6 percent fixed carbon, 3.3 percent water, 29.0 percent volatiles and 10 1 percent ash was used as a basis for these calculations. This is a high volatile grade A bituminous coal. The tar and oil yield from the coal is about 0 11 cubic meters per metric ton. Tars and oil present in the top gas are 22,000 milligrams per normal cubic meter. The temperature in the reducing zone is 980C. The metallization of the ultilnate product is 92 percent with the metallization taking place in the prereduction zone being 20 percent. The use of excess coal will result in carburizing the iron product.
~ LQ~5~L
Table 1 shows computed operating figures for a direct reduction furnace operated in accordance with the Tnvention, The gas analyses are typical operating figures at the locations indicated by the letter headings, These locations are as follows~
A, Top gas upon exit from top gas outlet 44, B. Gas exiting water-scrubber 60, C, Gas passing through vent Vl, D, Gas entering furnace inlet 78, E. Gas leaving the reduction zone, in the region of electrode 30.
Gas flows in the table are given in normal cubic meters per metric ton (Nm3/t) o~ Product.
~ Flow Nm3/t Prod,) ¦ 1300 1260 ~ 5 ~ 760 1280 Temp,-C 360 40 40 980 980 Analysis - %C0 49,t 50.7 50.7 53,9 65,6 %C2 23,3 24,1 24,1 20.9 8,3 %H2 17,0 17,6 17,6 14,4 21,0 %H20 9,0 6,0 6,o 9,2 4.5 %CH4 0,9 0,9 0,9 0,9 0,0 %N2 0,7 0,7 0.7 0,7 0,6 1 ~ 5~
Tests have been conducted to determine the electrical resistance at various temperatures of a packed bed burden consisting of 89 percent nominal 12 mm diameter pellets of approximately 90 percent metallization, lO percent nominal 12 mm diameter coal char from low volatile bitiminous coal and one percent limestone of nominal six mm diameter. In Table ll the resistivity represents the resistance through a burden having a face area one meter square and a resistance path depth of one meter. The table represents points taken from a curve of plotted data points:
TABLE II
Resistivity in Temperature Ohm-Meters 100C .0055 300C .0033 500C .0020 700C .Oû12 900C .0007 The preferred reduction temperature in the furnace of the present invention is in the range of 900 to 1000C, The burden resistivity in this temperature range at either low or high metallizations requires relatively high current at relatively low voltage wh;ch makes practical the resistance heating of the burden without need for sophisticated electrical insulation or grounding means.
S~MMARY OF THE ACHIEVEMENTS OF THE OBJECTS OF THE INVENTION
It is clear frorn the above that we have invented a method and apparatus for directly reducing iron oxide to molten iron in a shaft type reduction furnace utilizing solid fuel as the reductant source in which energy input requirements are greatly reduced over present cornmercial direct reduction plants and w h more efficient operat'on than was heretofore possible, 3L~ 5~
It is to be understood that the foregoing description and specific example are merely illustrative of the principles of the invention and that various modifications and additions may be made thereto by those skilled in the art without departing from the spirit and scope of the invention
Claims (24)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Apparatus for reducing particulate iron oxide to molten iron with a solid reductant, said apparatus comprising:
(a) a shaft furnace having a particle introducing means generally at the top thereof for establishing a gravita-tionally descending burden therein, a molten iron collection chamber at the bottom thereof, and molten iron removal means;
(b) an electrode positioned within said chamber adapted to contact molten metal within said chamber, at least one second electrode positioned in said furnace above said chamber and adapted to contact the particulate burden in said furnace, including an external source of electric power for passing an electric current through said burden;
(c) a gas outlet in the upper region of said furnace for removing reacted top gas;
(d) means external to said furnace for cooling and cleaning removed top gas, said cooling and cleaning means communicating with said means for removing top gas;
(e) means communicating with said top gas cooling and cleaning means and with the interior of said furnace for heating said cooled and cleaned top gas; and (f) means for introducing heated gas to said furnace in the lower region thereof.
(a) a shaft furnace having a particle introducing means generally at the top thereof for establishing a gravita-tionally descending burden therein, a molten iron collection chamber at the bottom thereof, and molten iron removal means;
(b) an electrode positioned within said chamber adapted to contact molten metal within said chamber, at least one second electrode positioned in said furnace above said chamber and adapted to contact the particulate burden in said furnace, including an external source of electric power for passing an electric current through said burden;
(c) a gas outlet in the upper region of said furnace for removing reacted top gas;
(d) means external to said furnace for cooling and cleaning removed top gas, said cooling and cleaning means communicating with said means for removing top gas;
(e) means communicating with said top gas cooling and cleaning means and with the interior of said furnace for heating said cooled and cleaned top gas; and (f) means for introducing heated gas to said furnace in the lower region thereof.
2. Apparatus according to claim 1 wherein said electrode within said chamber is a carbon block electrode.
3. Apparatus according to claim 1 further comprising at least one heat resistant alloy disc carried by said second electrode.
4. Apparatus according to claim 3 wherein said second electrode is journaled for rotation.
5. Apparatus according to claim 4 wherein said second electrode is connected to an oscillatible drive means.
6. Apparatus according to claim 4 wherein said electrode disc has teeth on its outer periphery whereby it is capable of acting as a cluster breaker.
7. Apparatus according to claim 6 wherein said electrode disc is a radially extending breaking segment extending from about 180 to about 270 degrees about the electrode.
8. Apparatus according to claim 1 further comprising means for sensing the burden temperature.
9. Apparatus according to claim 1 further comprising means for venting excess cleaned and cooled top gas.
10. Apparatus according to claim 1 wherein said means for cleaning removed top gas is a scrubber.
11. Apparatus according to claim 10 wherein said scrubber is an oil scrubber having sludge collecting means.
12. Apparatus according to claim 1 wherein said means for cooling spent top gas is a water scrubber.
13. Apparatus according to claim 1 wherein said particle introducing means includes at least one tube extending into said furnace and terminating a sufficient distance from the top there-of to form a reacted top gas plenum above the burden stock line.
14. Apparatus according to claim 11 further comprising a sludge return line for returning scrubber sludge to the interior of said furnace beneath the stock line, said return line communicating with said scrubber and terminating in said furnace beneath the burden stock line.
15. Apparatus according to claim 14 further comprising means for injecting cooled, cleaned top gas into said sludge return line to assist in injecting the sludge into said shaft furnace.
16. Apparatus according to claim 2 wherein said carbon block electrode covers the bottom and sides of said molten iron collection chamber.
17. Apparatus according to claim 1 wherein said second electrode extends across the entire furnace width.
18. A method of reducing particulate iron oxide material to molten iron with a solid reductant comprising.
(a) continuously feeding particulate iron oxide and solid particulate carbonaceous fuel to a particle inlet at the top of a shaft furnace to establish a packed burden therein;
(b) passing an electric current through the burden to provide sufficient heat by electric resistance heating to react said carbonaceous fuel with oxygen from said particulate iron oxide to reduce said iron oxide substantially to metallic iron and to melt the iron and to form a molten iron pool;
(c) causing the reaction products to move through said particulate burden in counterflow relation with it, and form a top gas;
(d) removing top gas from the upper region of the shaft furnace;
(e) cooling said top gas;
(f) preheating the cooled top gas;
(g) recirculating the heated gas to the burden through a gas inlet at the lower region of said furnace above said molten metal pool; and (h) removing molten iron product and slag from an outlet at the bottom of said furnace.
(a) continuously feeding particulate iron oxide and solid particulate carbonaceous fuel to a particle inlet at the top of a shaft furnace to establish a packed burden therein;
(b) passing an electric current through the burden to provide sufficient heat by electric resistance heating to react said carbonaceous fuel with oxygen from said particulate iron oxide to reduce said iron oxide substantially to metallic iron and to melt the iron and to form a molten iron pool;
(c) causing the reaction products to move through said particulate burden in counterflow relation with it, and form a top gas;
(d) removing top gas from the upper region of the shaft furnace;
(e) cooling said top gas;
(f) preheating the cooled top gas;
(g) recirculating the heated gas to the burden through a gas inlet at the lower region of said furnace above said molten metal pool; and (h) removing molten iron product and slag from an outlet at the bottom of said furnace.
19. A method according to claim 18 wherein said particulate carbonaceous fuel is coal.
20. A method according to claim 18 wherein said particulate carbonaceous fuel is lignite.
21. A method according to claim 18 wherein said particulate carbonaceous fuel is coke.
22. A method according to claim 18 further comprising adding limestone, dolomite, or a mixture thereof to said feed material.
23. A method according to claim 18 further comprising cleaning said removed top gas in a scrubber, and returning the scrubber underflow to the interior of said furnace beneath the stock line of said burden.
24. A method according to claim 23 further comprising injecting a portion of the cleaned top gas into the scrubber underflow to assist in returning the underflow to said furnace.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/892,564 US4179278A (en) | 1977-02-16 | 1978-04-03 | Method for reducing particulate iron oxide to molten iron with solid reductant |
| US892,564 | 1992-06-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1110454A true CA1110454A (en) | 1981-10-13 |
Family
ID=25400142
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA322,944A Expired CA1110454A (en) | 1978-04-03 | 1979-03-07 | Method and apparatus for reducing particulate iron oxide to molten iron with solid reductant |
Country Status (19)
| Country | Link |
|---|---|
| JP (1) | JPS54138809A (en) |
| AR (1) | AR217910A1 (en) |
| AT (1) | AT367455B (en) |
| AU (1) | AU523466B2 (en) |
| BR (1) | BR7901905A (en) |
| CA (1) | CA1110454A (en) |
| DE (1) | DE2913340A1 (en) |
| ES (1) | ES479236A1 (en) |
| GB (1) | GB2017883B (en) |
| GR (1) | GR66661B (en) |
| IN (1) | IN150938B (en) |
| IT (1) | IT1113339B (en) |
| KE (1) | KE3318A (en) |
| NZ (1) | NZ190049A (en) |
| PH (2) | PH14626A (en) |
| PL (1) | PL214642A1 (en) |
| PT (1) | PT69420A (en) |
| TR (1) | TR20987A (en) |
| ZA (1) | ZA791385B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62122077U (en) * | 1986-01-21 | 1987-08-03 | ||
| JPS62122078U (en) * | 1986-01-21 | 1987-08-03 |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1057213A (en) * | 1912-04-09 | 1913-03-25 | George Hillard Benjamin | Electric furnace and method of operating same. |
| US1937064A (en) * | 1925-01-05 | 1933-11-28 | Pittsburgh Res Corp | Method of treating metals |
| DE2210468C3 (en) * | 1972-03-04 | 1979-03-22 | Kloeckner-Werke Ag, 4100 Duisburg | Process for continuously producing steel from ore or the like |
| US3948640A (en) * | 1973-04-30 | 1976-04-06 | Boliden Aktiebolag | Method of carrying out heat-requiring chemical and/or physical processes |
| DE2327073C2 (en) * | 1973-05-26 | 1974-11-21 | Kloeckner-Werke Ag, 4100 Duisburg | Method and device for melting down scrap or the like |
| US3844766A (en) * | 1973-12-26 | 1974-10-29 | Midland Ross Corp | Process for reducing iron oxide to metallic sponge iron with liquid or solid fuels |
| US4082543A (en) * | 1977-02-16 | 1978-04-04 | Midrex Corporation | Method for reducing particulate iron oxide to metallic iron with solid reductant |
-
1979
- 1979-03-07 CA CA322,944A patent/CA1110454A/en not_active Expired
- 1979-03-20 AU AU45266/79A patent/AU523466B2/en not_active Ceased
- 1979-03-21 IN IN278/CAL/79A patent/IN150938B/en unknown
- 1979-03-22 AR AR275907A patent/AR217910A1/en active
- 1979-03-22 ZA ZA791385A patent/ZA791385B/en unknown
- 1979-03-26 GB GB7910504A patent/GB2017883B/en not_active Expired
- 1979-03-28 PH PH22330A patent/PH14626A/en unknown
- 1979-03-29 BR BR7901905A patent/BR7901905A/en unknown
- 1979-03-30 AT AT0239579A patent/AT367455B/en not_active IP Right Cessation
- 1979-03-30 PT PT69420A patent/PT69420A/en unknown
- 1979-03-30 NZ NZ190049A patent/NZ190049A/en unknown
- 1979-03-30 TR TR20987A patent/TR20987A/en unknown
- 1979-04-02 JP JP3969079A patent/JPS54138809A/en active Granted
- 1979-04-02 IT IT21495/79A patent/IT1113339B/en active
- 1979-04-03 ES ES479236A patent/ES479236A1/en not_active Expired
- 1979-04-03 PL PL21464279A patent/PL214642A1/xx unknown
- 1979-04-03 GR GR58775A patent/GR66661B/el unknown
- 1979-04-03 DE DE19792913340 patent/DE2913340A1/en active Granted
- 1979-11-23 PH PH23320A patent/PH15052A/en unknown
-
1983
- 1983-08-08 KE KE3318A patent/KE3318A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| GB2017883B (en) | 1982-06-03 |
| IT1113339B (en) | 1986-01-20 |
| ZA791385B (en) | 1980-05-28 |
| IT7921495A0 (en) | 1979-04-02 |
| DE2913340C2 (en) | 1987-10-15 |
| IN150938B (en) | 1983-01-22 |
| PT69420A (en) | 1979-04-01 |
| PH15052A (en) | 1982-05-20 |
| AU523466B2 (en) | 1982-07-29 |
| AT367455B (en) | 1982-07-12 |
| GR66661B (en) | 1981-04-07 |
| NZ190049A (en) | 1980-08-26 |
| KE3318A (en) | 1983-08-26 |
| DE2913340A1 (en) | 1979-10-11 |
| PH14626A (en) | 1981-10-12 |
| ATA239579A (en) | 1981-11-15 |
| AR217910A1 (en) | 1980-04-30 |
| PL214642A1 (en) | 1980-01-28 |
| ES479236A1 (en) | 1980-01-16 |
| JPS54138809A (en) | 1979-10-27 |
| JPS5757929B2 (en) | 1982-12-07 |
| GB2017883A (en) | 1979-10-10 |
| BR7901905A (en) | 1979-11-27 |
| TR20987A (en) | 1983-03-25 |
| AU4526679A (en) | 1979-10-18 |
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