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
  • C21B13/0006—Making spongy iron or liquid steel, by direct processes obtaining iron or steel in a molten state
  • C21B13/0013—Making spongy iron or liquid steel, by direct processes obtaining iron or steel in a molten state introduction of iron oxide into a bath of molten iron containing a carbon reductant
  • C21B13/002—Reduction of iron ores by passing through a heated column of carbon
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B11/00—Making pig-iron other than in blast furnaces
  • C21B11/02—Making pig-iron other than in blast furnaces in low shaft furnaces or shaft 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
  • C21B13/0033—In fluidised bed furnaces or apparatus containing a dispersion of the material
• • 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
  • C21B2100/00—Handling of exhaust gases produced during the manufacture of iron or steel
  • C21B2100/20—Increasing the gas reduction potential of recycled exhaust gases
  • C21B2100/22—Increasing the gas reduction potential of recycled exhaust gases by reforming
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B2100/00—Handling of exhaust gases produced during the manufacture of iron or steel
  • C21B2100/40—Gas purification of exhaust gases to be recirculated or used in other metallurgical processes
  • C21B2100/44—Removing particles, e.g. by scrubbing, dedusting
• • 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 fluidized bed type reducing apparatus for reducing a fine iron ore of a wide particle size distribution in a fluidized state, and a method for reducing the fine iron ore by using the apparatus. More specifically, the present invention relates to a fluidized bed type fine iron ore reducing apparatus and a method therefor, in which the reduction is carried out by classifying the particle sizes of the fine iron ore, thereby minimizing the particle elutriation loss .
• the blast furnace method forms the main stream.
• the shaft type smelting reduction process using the pellets and lump ore has been commercialized to produce the molten iron.
• the above two processes have the restriction that only agglomerated raw materials can be used.
• a sintered ore which is made by mixing coke (made from coal as a fual), a fine iron ore and an auxiliary raw material, thereby producing a molten pig iron.
• coke made from coal as a fual
• a fine iron ore and an auxiliary raw material, thereby producing a molten pig iron.
• the facility for the pre-treatment of the raw material is increased, and in this connection, the environmental pollution problem has become serious. Therefore, regarding this matter, the environmental regulation has been imposed.
• the shaft type smelting reduction iron producing process there are used the iron ore pellets made from the fine ore as the raw material, or there are used the lump iron ore of limited sizes, to produce the molten pig iron.
• the fluidized bed type smelting reduction process is calling the attentions as a means to replace the existing blast furnace method, because the fluidized bed type smelting reduction process can directly use the fine iron ore which is cheap and profusely buried. Therefore, studies on the fluidized bed type furnace are being briskly carried out.
• the smelting reduction process is divided into a pre- reducing stage and a final reducing stage.
• the raw ore is pre-reduced into a solid state
• the pre-reduced iron is put into a elter-gasifier to produce a finally reduced pig iron.
• the pre-reducing stage is classified into moving bed type and a fluidized bed type based on the particle sizes. It is known that the fluidized bed type is advantageous in the case of a fine iron ore of a wide particle size distribution, because the fluidized bed type furnace reduces the raw iron ore by means of the reducing gas within the reducing furnace. That is, the fluidized bed type furnace is efficient in the bed permeability and the gas utilization.
• the fluidized bed type molten pig iron manufacturing apparatus includes: a first fluidized bed type furnace 110 having a conical shape with a wide top and a narrow bottom so as to stably fluidize a fine iron ore of a wide particle size distribution, for drying/preheating the fine iron ore under a bubble fluidizing state to improve the reduction rate and the gas utilization rate; a first cyclone 140 for collecting fine iron ore particles contained in the discharge gas of the first fluidized bed type furnace; a second fluidized bed type furnace 120 for pre-reducing the fine iron ore after its drying/pre-heating by the first fluidized bed type furnace; a second cyclone 150 for collecting fine iron ore particles contained in the discharge gas of the second fluidized bed type furnace; a third fluidized bed type furnace 130 for finally reducing the fine iron ore after its pre-reduction by the second fluidized bed type furnace; a third cyclone 160 for collecting fine iron ore particles contained in the discharge gas of the third fluidized bed type furnace; and a melter-
• the fine iron ore which has not been captured by the first cyclone 140 is discharged through a gas discharge hole, with the result that the elutriation loss of the iron ore is very large.
• the degradation phenomenon occurs mostly at the early stage of the reduction. Therefore, a large amount of fine iron ore is elutriated after it is degraded during the first pre-reduction by the first fluidized bed type furnace 110 and during the mechanical degradation by the fluidizing.
• the first cyclone is overloaded, and therefore, the separation of the iron ore from the discharge gas is inhibited, with the result that a large amount of fine iron ore is discharged together with the discharge gas, thereby increasing the loss.
• the reduced iron of a wide particle distribution which has been finally reduced by the third fluidized bed type furnace 130, is fed into the melter- gasifier 180, the fine reduced iron particles are dropped to below the melter-gasifier so as to be scattered away.
• a fluidized bed type reducing apparatus was disclosed by the present inventors under Korean Patent Application No. 97-71432. In this apparatus also, there have been found the problems that the cyclones are overloaded by the fine particles coming from the final pre-reducing furnace, and that the efficiency is lowered.
• the present invention is intended to overcome the above described disadvantages of the conventional techniques.
• the present inventors have carried out studies and researches for a long time, and based on the studies and researches, the present inventors came to propose the apparatus of the present invention.
• the fluidized bed type fine iron ore reducing apparatus for reducing a fine iron ore of a wide particle size distribution includes: a first fluidized bed type furnace for carrying out a first reduction on only coarse /intermediate iron ores among fine iron ores of a wide particle size distribution by forming a bubble fluidizing bed after their charge from a charging hopper, while making fine iron ore particles fly away; a second fluidized bed type furnace for carrying out a reduction for a second time on the coarse/intermediate iron ores discharged from the first fluidized bed type furnace; a first cyclone for capturing fine iron ore particles elutriated from the first fluidized bed type furnace; a second cyclone for capturing fine iron ore particles elutriated from the second fluidized bed type furnace; a third fine particle fluidized bed type furnace for carrying out a second reduction on the iron ores captured by the first and second cyclones, by forming a bubble fluidizing bed; a third cycl
• the fluidized bed type fine iron ore reducing apparatus for reducing a fine iron ore of a wide particle size distribution includes: a first fluidized bed type furnace for carrying out a first reduction on only coarse/intermediate iron ores among fine iron ores of a wide particle size distribution by forming a bubble fluidizing bed after their charge from a charging hopper, while making fine iron ore particles fly away; a second fine particle fluidized bed type furnace for carrying out a first reduction on the fine iron ore particles discharged from the first fluidized bed type furnace; a first cyclone for capturing extremely fine iron ore particles elutriated from the second fluidized bed type furnace; a third fluidized bed type furnace for carrying out a second reduction on the iron ores first-reduced by the first and second fluidized bed type furnaces, by forming a bubble fluidizing bed; a second cyclone for capturing an extremely fine iron ore elutriated from the third fluidized bed type furnace.
• the present invention also provides a method for manufacturing a reduced iron by using the above described apparatus.
• FIG. 1 illustrates the conventional fluidized bed type reducing apparatus for reducing a fine iron ore
• FIG. 2 illustrates an example of the fluidized bed type reducing apparatus for reducing a fine iron ore according to the present invention
• FIG. 3 illustrates another example of the fluidized bed type reducing apparatus for reducing a fine iron ore according to the present invention
• FIG. 4 illustrates still another example of the fluidized bed type reducing apparatus for reducing a fine iron ore according to the present invention.
• FIG. 2 illustrates an example of the fluidized bed type reducing apparatus for reducing a fine iron ore according to the present invention.
• the fluidized bed type fine iron ore reducing apparatus 200 for reducing a fine iron ore of a wide particle size distribution includes: a first fluidized bed type furnace 210 for carrying out a first reduction on only coarse/ intermediate iron ores among fine iron ores of a wide particle size distribution by forming a bubble fluidizing bed after their charge from a charging hopper 205, while making fine iron ore particles fly away; a second fluidized bed type furnace 220 for carrying out a reduction for a second time on the coarse/intermediate iron ores discharged from the first fluidized bed type furnace 210; a first cyclone 240 for capturing fine iron ore particles elutriated from the first fluidized bed type furnace 210; a second cyclone 250 for capturing fine iron ore particles elutriated from the second fluidized bed type furnace 220; a third fine particle fluidized bed type furnace 230 for carrying out a second reduction on the iron ores captured by the first and second cyclones 240
• the first fluidized bed type furnace 210 is cylindrical, and a first gas supplying pipe 253 is connected to the bottom of the furnace 210, for supplying the reducing gas into the reducing furnace, while a first gas distributor 212 is installed in the lower portion of it.
• a first charging pipe 201 is connected to a side wall of the first fluidized bed type furnace 210, for supplying a fine iron ore from the charging hopper 205.
• a first discharge pipe 211 is connected to the side wall of the second fluidized bed type furnace 220, for discharging the pre-reduced intermediate/coarse iron ores .
• the top of the first fluidized bed type furnace 210 is connected through a first discharge gas discharging pipe 213 to the first cyclone 240. Further, a first circulation pipe 241 is connected to the bottom of the first cyclone 240, for circulating the fine iron ore particles (which are contained in the discharge gas of the first fluidized bed type furnace) to the third fluidized bed type furnace 230. A fourth discharge gas discharging pipe 243 is connected to the top of the first cyclone 240, for discharging the discharge gas after the separation of the fine iron ore particles.
• the second fluidized bed type furnace 220 is cylindrical, and a second gas supplying pipe 271 is connected to the bottom of the furnace 220, while a second gas distributor 222 is installed in the lower portion of the furnace 220.
• a first charging pipe 201 is connected to a side wall of said first fluidized bed type furnace, for supplying a fine iron ore from said hopper 205 to said first furnace 210.
• a first discharge pipe 211 is connected to the side wall of the first fluidized bed type furnace 210, first fluidized bed type furnace 210, for discharging the first-reduced intermediate/coarse iron ore particles from the first fluidized bed type furnace 210 to the second fluidized bed type furnace 220.
• the top of the second fluidized bed type furnace 220 is connected through a second discharge gas discharging pipe 223 to the second cyclone 250.
• a second circulation pipe 251 is connected to the bottom of the second cyclone 250, for circulating a fine iron ore particles (which are contained in the discharge gas of the second fluidized bed type furnace 220) to the third fluidized bed type furnace 230.
• a first gas supplying pipe 253 is connected to the top of the second cyclone 250, for supplying the discharge gas after its separation from the fine iron ore particles. As shown in FIG.
• the second circulating pipe 251 communicates to the first circulating pipe 241, and thus, the fine iron ore particles which are contained in the discharge gas of the second fluidized bed type furnace 220 are supplied through the second and first circulating pipes 251 and 241 to the third fluidized bed type furnace 230.
• the present invention is not limited to the above described structure, but the second circulating pipe 251 may be directly connected to the third fluidized bed type furnace 230.
• the third fine particle fluidized bed type furnace 230 includes an expanded portion 230a, a tapered portion 230b and a narrow portion 230c.
• a third gas distributor 232 Within the lower portion of the narrow portion 230c, there is installed a third gas distributor 232. Further, a third reducing gas supplying pipe 272 is connected to the bottom of the third fluidized bed type furnace 230, for supplying a reducing gas .
• a third discharging pipe 231 is connected to the side wall of the narrow portion 230c (above the third gas distributor 232), for discharging the reduced fine iron particles from the third fluidized bed type furnace 230.
• the expanded portion 230a of the third fluidized bed type furnace 230 is connected through a third discharge gas discharging pipe 233 to the third cyclone 260.
• a third circulating pipe 261 is connected to the bottom of the third cyclone 260, for circulating the fine iron ore particles (which are contained in the discharge gas of the third fluidized bed type furnace 230) back to the third fluidized bed type furnace 230.
• a fifth discharge gas discharging pipe 263 is connected to the top of the third cyclone 260, for discharging the discharge gas after its separation from the fine iron ore particles.
• the fifth discharge gas discharging pipe 263 should be preferably connected to a fourth discharge gas discharging pipe 243.
• the fifth discharge gas discharging pipe 263 may not be connected to a fourth discharge gas discharging pipe 243.
• the first circulating pipe 251 extends down to the lower interior of the third fluidized bed type furnace 230 after passing through the expanded portion 230a of the third fluidized bed type furnace 230.
• the height of the first and second fluidized bed type furnaces 210 and 220 should be preferably 10 - 15 times as large as the inner diameter of them. The reason is as follows. That is, if the height is less than 10 times the inner diameter, the fluidizing of the iron ore particles is not efficient within the furnace, and therefore, even the intermediate/coarse iron ore particles may fly away. On the other hand, if the height is more than 15 times the inner diameter, then the fine iron ore particles cannot efficiently fly.
• the inner diameter of the narrow portion 230c of the third fluidized bed type furnace 230 is just as large as the inner diameter of the bottom of the tapered portion 230b.
• the inner diameter of the expanded portion 230a is just as large as the inner diameter of the top of the tapered portion 230b.
• the inner diameter of the expanded portion 230a should be preferably 1.5 - 2.0 times as large as the inner diameter of the narrow portion, so that the gas flow velocity can be reduced within the furnace while inhibiting the elutriation of the fine iron ore particles.
• the overall height of the third fluidized bed type furnace 230 should be preferably 10 - 20 times as large as the inner diameter of the narrow portion, so that a sufficient fluidizing space can be secured, and that the elutriation of the fine iron ore particles can be inhibited.
• the height of the narrow portion 230c should be preferably 1.0 - 1.5 times as large as the height of the expanded portion 230a.
• the inclination of the tapered portion 230b should be preferably 30 - 50° relative to the vertical line.
• FIG. 3 illustrates another example of the fluidized bed type reducing apparatus for reducing a fine iron ore according to the present invention.
• the fluidized bed type fine iron ore reducing apparatus 300 for reducing a fine iron ore of a wide particle size distribution includes: a first fluidized bed type furnace 310 for carrying out a first reduction on only coarse /intermediate iron ores among fine iron ores of a wide particle size distribution by forming a bubble fluidizing bed after their charge from a charging hopper, while making fine iron ore particles fly away; a second fluidized bed type furnace 320 for carrying out a reduction for a second time on the coarse/intermediate iron ores discharged from the first fluidized bed type furnace; a first cyclone 340 for capturing fine iron ore particles elutriated from the first fluidized bed type furnace 310; a second cyclone 350 for capturing fine iron ore particles elutriated from the second fluidized bed type furnace 320; a third fine particle fluidized bed type furnace 330 for carrying out a second reduction on the iron ores captured by the first and second cyclones 340 and
• the first fluidized bed type furnace 310 is cylindrical, and a first gas distributor 312 is installed within the lower portion of it.
• a first gas supplying pipe 355 is connected to the bottom of the furnace 310, for supplying the discharge gases of the second and third fluidized bed type furnaces 320 and 330 as reducing gases into the first fluidized bed type furnace 310.
• a first charging pipe 301 is connected to a side wall of the first fluidized bed type furnace 310, for supplying a fine iron ore and a flux such as lime stone from the charging hopper.
• a first discharge pipe 311 is connected to the side wall of the second fluidized bed type furnace 320, for discharging the pre-reduced intermediate/coarse iron ores.
• the top of the first fluidized bed type furnace 310 is connected through a first discharge gas discharging pipe 313 to the first cyclone 340.
• a first fine ore supplying pipe 343 is connected to the bottom of the first cyclone 340, for supplying the fine iron ore particles (which are contained in the discharge gas of the first fluidized bed type furnace 310) back to the first fluidized bed type furnace 310.
• the first fine ore supplying pipe 343 should be extended into the lower portion of the first fluidized bed type furnace 310.
• a sixth discharge gas discharging pipe 344 is connected to the first cyclone 340, for discharging the discharge gas of the first fluidized bed type furnace 310 after its separation from the fine iron ore particles.
• a second fine particle supplying pipe 342 is connected to the first fine particle supplying pipe 343, for supplying the fine iron ore particles to the third fluidized bed type furnace 330. Between the first and second fine particle supplying pipes 343 and 342, there is disposed a first two-way valve 341.
• the second fluidized bed type furnace 320 is cylindrical, and a second gas distributor 322 is installed within the lower portion of it.
• a second reducing gas supplying pipe 371 is connected to the bottom of the furnace 320.
• the top of the second fluidized bed type furnace 320 is connected through a second discharge gas discharging pipe 323 to the second cyclone 350.
• a third fine particle supplying pipe 353 is connected to the bottom of the second cyclone 350, for supplying the fine iron ore particles which are contained in the discharge gas of the second fluidized bed type furnace 320.
• the third fine particle supplying pipe 353 should be extended down to the lower interior of the second fluidized bed type furnace 320.
• a fourth fine particle supplying pipe 354 is connected to the third fine particle supplying pipe 353, for supplying the fine iron ore particles to the third fluidized bed type furnace 330.
• the fourth fine particle supplying pipe 354 should be extended down to the lower interior of the third fluidized bed type furnace 330.
• a second two-way valve 352 is installed at a connection portion between said third and fourth fine particle supplying pipes 353 and 354.
• a first reducing gas supplying pipe 355 is connected to the second cyclone 350, for supplying the discharge gas as a reducing gas after its separation from the fine iron ore particles.
• the first reducing gas supplying pipe 355 is connected to the bottom of the first fluidized bed type furnace 310.
• the third fine particle fluidized bed type furnace 330 is cylindrical, and a first gas dispersing plate 332 is installed in the lower portion of it.
• a third reducing gas supplying pipe 372 is connected to the bottom of the third fine particle fluidized bed type furnace 330, for supplying a reducing gas .
• the second and third reducing gas supplying pipes 371 and 372 should be preferably connected to the melter-gasifier 380 so as to use the discharge gas of the melter-gasifier 380 as a reducing gas.
• a third discharging pipe 331 is connected to the side wall of the third fine particle fluidized bed type furnace 330, for discharging the reduced fine iron ore particles. Further, a second fine particle supplying pipe 342 is connected to the side wall of the third fine particle fluidized bed type furnace 330, for supplying the fine iron ore particles which have been captured by the first cyclone 340.
• the top of the third fine particle fluidized bed type furnace 330 is connected through a third discharge gas discharging pipe 333 to the third cyclone 360.
• a fifth fine particle supplying pipe 361 is connected to the lower portion of the third cyclone 360, for supplying the fine iron ore particles (which are contained in the discharge gas of the third fine particle fluidized bed type furnace 330) back to the third fine particle fluidized bed type furnace 330.
• a fourth discharge gas discharging pipe 362 is connected to the top of the third cyclone 360, for discharging the discharge gas after its separation from the fine iron ore particles.
• the fourth discharge gas discharging pipe 362 is connected to the first reducing gas supplying pipe 355.
• the second and third reducing gas supplying pipes 371 and 372 should be preferably provided with first and second flow rate adjusting valves 375 and 377 respectively.
• the second and third reducing gas supplying pipes 371 and 372 are connected to the top of the melter-gasifier 380, and are also connected to a fifth discharge gas discharging pipe 383 which discharges the discharge gas of the melter-gasifier 380. Further, a second discharging pipe 321 is connected to the melter- gasifier 380 for the circulation of the iron ore.
• a third discharging pipe 331 is connected to a melting furnace 335.
• Oxygen (0 2 ) should be preferably supplied to the first, second and third reducing gas supplying pipes 355, 371 and 372.
• reference code 381 indicates the molten iron
• 382 indicates the coal layer.
• FIG. 4 illustrates still another example of the fluidized bed type reducing apparatus for reducing a fine iron ore according to the present invention.
• the fluidized bed type fine iron ore reducing apparatus 400 for reducing a fine iron ore of a wide particle size distribution includes: a first fluidized bed type furnace 410 for receiving a reducing gas through its bottom, and for receiving a fine iron ore through a charging hopper 405 and first charging pipe 401, to carry out a first reduction on only coarse/intermediate iron ores among fine iron ores of a wide particle size distribution by forming a bubble fluidizing bed, while making fine iron ore particles fly away; a second fine particle fluidized bed type furnace 420 with a wide top and a narrow bottom, for carrying out a first reduction on the fine iron ores discharged from the first fluidized bed type furnace, by forming a bubble fluidizing bed; a first cyclone 440 for capturing extremely fine iron ore particles elutriated from the second fluidized bed type furnace, and for discharging the final discharge gas after its separation from fine iron ore particles; a third fluidized bed type furnace 430 for
• a first gas supplying pipe 414 is connected to the bottom of the first fluidized bed type furnace 410, for supplying a reducing gas into the furnace 410, while a gas distributor 412 is installed in the lower portion of the furnace 410.
• a first charging pipe 401 connected to a charging hopper for supplying a fine iron ore and a flux such as lime stone or the like into the fluidized bed;
• a first discharging pipe for discharging a first-reduced intermediate/coarse iron ores into the third fluidized bed type furnace 430;
• a first circulating pipe 415 for supplying the elutriated fine iron ore particles to the second fluidized bed type furnace 420.
• the first circulating pipe 415 is disposed above the first discharging pipe 411.
• the second fine particle fluidized bed type furnace 420 includes an expanded portion 420a, a tapered portion 420b and a narrow portion 420c, its top portion being wide and its bottom portion being narrow, A second gas distributor 422 is installed within the narrow portion 420c, while a second reducing gas supplying pipe 427 is connected to the bottom of the second fluidized bed type furnace 420, for supplying the discharge gas of the third fluidized bed type furnace 430 as a reducing gas.
• a second discharging pipe 421 for discharging the first-reduced fine iron ore particles.
• the second discharging pipe 421 extends into a narrow portion 430c of the third fluidized bed type furnace 430, and in this manner, the second and third fluidized bed type furnaces 420 and 430 communicate to each other for circulations of the iron ore.
• a first circulating pipe 415 for supplying into the second fine particle fluidized bed type furnace 420 the fine iron ore particles which have been elutriated from the first fluidized bed type furnace 410 and which have been captured by the first cyclone 440.
• the expanded portion 420a of the second fine particle fluidized bed type furnace 420 is connected through a first discharge gas discharging pipe 423 to the first cyclone 440.
• a second circulating pipe 441 communicates to the first circulating pipe 415.
• a second discharge gas discharging pipe 443 is connected to the top of the first cyclone 440, for discharging the discharge gas which has been separated from the fine iron ore particles.
• the third fluidized bed type furnace 430 includes an expanded portion 430a, a tapered portion 430b and a narrow portion 430c, its top portion being wide and its bottom portion being narrow.
• a gas distributor 432 is installed in the narrow portion 430c, while a third reducing gas supplying pipe 471 is connected to the bottom of the third fluidized bed type furnace 430, for supplying a reducing gas.
• a fourth discharging pipe 431 is connected to the side wall of the third fluidized bed type furnace 430, so that the second-reduced iron of the third fluidized bed type furnace 430 can be discharged to the outside.
• the fourth discharging pipe 431 should be connected through a screw conveyor 435 to the third fluidized bed type furnace 430, thereby discharging the reduced iron to the melter-gasifier 480.
• the expanded portion 430a of the third fluidized bed type furnace 430 is connected through a third discharge gas discharging pipe 433 to the second cyclone 450.
• a circulating pipe 451 is connected to the bottom of the second cyclone 450. This circulating pipe 451 is also connected to: a third circulating pipe 454 for circulating a part of the fine iron ore particles (contained in the discharge gas of the third fluidized bed type furnace 430) back to the third fluidized bed type furnace 430; and a third discharging pipe 455 for discharging the rest of the fine iron ore particles to the outside.
• a rotary gate 452 which feeds a part of the fine iron ore particles (captured by the second cyclone 450) into the third fluidized bed type furnace 430, and discharges the remaining part to the outside.
• a fourth discharge gas discharging pipe 453 is connected to the top of the second cyclone 450, for discharging the discharge gas after its separation from the fine iron ore particles.
• the fourth discharge gas discharging pipe 453 communicates to a first reducing gas supplying pipe 414 of the first fluidized bed type furnace 410, and to a second reducing gas supplying pipe 427 of the second fine particle fluidized bed type furnace 420.
• the gas reforming system 460 is made to communicate through a reformed gas supplying pipe 462 to the fourth discharge gas discharging pipe 453, and is also made to communicate through a discharge gas circulating pipe 461 to the second discharge gas discharging pipe 443.
• the fluidized bed type reducing apparatus 400 should preferably include a melter-gasifier 480 which receives the second-reduced iron from the third fluidized bed type furnace 430 to melt-reduce it into a molten iron.
• the melter-gasifier 480 is provided with a third cyclone 484, and this third cyclone 484 captures the fine iron ore particles from the discharge gas of the melter- gasifier 480 to circulate them back to the melter-gasifier 480.
• the discharge gas which has been separated from the fine iron ore particles is discharged through the top of the third cyclone 484.
• the top of the melter-gasifier 480 is connected through a fifth discharge gas discharging pipe 481 to the third cyclone 484.
• a fourth circulating pipe 482 is connected to the bottom of the third cyclone 484, so that the fine iron ore particles contained in the discharge gas of the melter- gasifier 480 can be circulated back to the melter-gasifier 480.
• a third reducing gas supplying pipe 436 is connected to the top of the third cyclone 484, for discharging the discharge gas. This third reducing gas supplying pipe 436 is connected to the bottom of the third fluidized bed type furnace 430, for supplying the discharge gas of the melter-gasifier 480 to the third furnace 430.
• the third fluidized bed type furnace 430 is connected through a fourth discharging pipe 431 to the melter-gasifier 480, for circulation of the iron ore.
• the height of the first fluidized bed type furnace 410 should be preferably 10-20 times as large as its own inner diameter. The reason is as follows. That is, if the height is less than 10 times, the fluidizing of the iron ore within the furnace cannot be efficient, and therefore, even the intermediate/coarse iron ore particles may fly into the second fluidized bed type furnace 420. On the other hand, if the height is more than 20 times, then the elutriation of the fine iron ore particles cannot be efficient.
• the inner diameters of the narrow portions 420c and 430c of the second and third fluidized bed type furnaces 420 and 430 are maintained at the inner diameters of the bottoms of the tapered portions 420b and 430b, while the inner diameters of the expanded portions 420a and 430a are maintained at the inner diameters of the tops of the tapered portions 420b and 430b.
• the inner diameters of the expanded portions 420a and 430a should be preferably 1.5 - 2.0 times as large as the inner diameters of the narrow portions, so that the gas flow velocity within the furnaces can be decreased so as to inhibit the elutriation of the fine iron ore particles.
• the overall heights of the second and third fluidized bed type furnaces 420 and 430 should be preferably 10 - 25 times as large as the inner diameters of the narrow portions, so that a sufficient fluidizing space can be secured, and that the elutriation of the fine iron ore particles can be inhibited.
• the heights of the narrow portions 420c and 430c should be preferably 1.0 - 1.5 times as large as the height of the expanded portions 420a and 430a.
• the inclination of the tapered portions 420b and 430b should be preferably 30 - 50° relative to the vertical line.
• a fine iron ore is charged from the charging hopper 205 through the first charging pipe 201 into the first fluidized bed type furnace 210.
• the fine iron ore particles are flown away, while the intermediate/coarse iron ores are first-reduced by forming a bubble fluidizing bed within the first fluidized bed type furnace 210 by the action of the reducing gas which has been introduced through the first gas supplying pipe 253 and has passed through the first gas distributor 212.
• the intermediate/coarse iron ores which have been first-reduced by the first fluidized bed type furnace 210 are supplied through the first discharging pipe 211 into the middle portion of the fluidized bed of the second fluidized bed type furnace 220 so as to be reduced for a second time by the reducing gas which has been supplied through the second gas supplying pipe 271.
• the fine iron ore particles are flown loaded in the discharge gas like in the first fluidized bed type furnace 210.
• the fine iron ore particles which have been flown from the first and second fluidized bed type furnaces 210 and 220 are separated from the gas by the first and second cyclones 240 and 250. Then the fine iron ore particles are supplied through the first circulating pipe 241 and the second circulating pipe 251 into the third fine particle fluidized bed type furnace 230, and are reduced for a second time by the reducing gas which has been introduced through the third gas supplying pipe 272.
• the extremely fine iron ore particles which have been flown loaded in the gas from the third fine particle fluidized bed type furnace 230 are separated from the gas by the third cyclone 260, and then, are circulated through the third circulating pipe 261 back to the third fine particle fluidized bed type furnace 230.
• the reduced iron which has been reduced twice by the second and third fluidized bed type furnaces 220 and 230 is finally discharged through the second and third discharging pipes 221 and 231.
• the third fine particle fluidized bed type furnace 230 is provided as a fine iron ore reducing furnace for reducing the fine iron ore particles which have been discharged from the first and second cyclones 240 and 250.
• the cyclones have a sufficient fine particle capturing capability, and therefore, the dust content in the gas is greatly lowered, with the result that an effective treatment of the fine iron ore particles is rendered possible.
• the gas flow velocity within the first and second fluidized bed type furnaces 210 and 220 should be preferably 1.2 - 2.5 times as fast as the minimum fluidizing velocity of the iron ore particles which stay within the furnaces. In this manner, the separation of the fine iron ore particles from the intermediate/coarse particles can be efficiently carried out, as well as promoting their movements .
• the gas flow velocity within the third fine particle fluidized bed type furnace 230 should be preferably 1.2 - 2.0 times as fast as the minimum fluidizing velocity of the iron ore particles which stay within the furnace.
• the fine iron ore is charged into the first fluidized bed type furnace 310, and the reducing gas of the first furnace 310 is the discharge gases of the second and third fluidized bed type furnaces 320 and 330. Under this condition, if the target temperature of the first fluidized bed type furnace 310 cannot be attained by the discharge gases of the second and third fluidized bed type furnaces 320 and 330, then oxygen is injected to raise the temperature of the reducing gas, thereby adjusting the internal temperature of the first fluidized bed type furnace 310.
• the coarse/intermediate iron ore particles are first- reduced by the reducing gas incoming through the first reducing gas supplying pipe 355, but also a degradation phenomenon occurs, thereby steeply increasing the content of the fine iron ore particles .
• Such large amounts of fine particles are captured by the first cyclone 340.
• the first two- way valve 341 is opened toward the first fluidized bed type furnace 310, so that the fine particles of the first cyclone 340 can be recycled.
• the first two-way valve 341 is opened toward the third fine particle fluidized bed type furnace 330 to feed the fine particles into the third fluidized bed type furnace 330.
• the fine iron ore particles are treated without recycling them when they are steadily outputted from the first fluidized bed type furnace 310.
• the load of the first cyclone 340 is alleviated, so that it can show a good efficiency.
• the discharge gas which has been separated from the fine iron ore particles by the first cyclone 340 is scrubbed to remove the dusts by the help of a wet type dust remover 390.
• the first-reduced intermediate/coarse iron ore ores which have not been flown away at the first fluidized bed type furnace 310 are supplied to the second fluidized bed type furnace 320 so as to be finally reduced.
• oxygen is injected to adjust the temperature of the second fluidized bed type furnace 320.
• the fine iron ore particles which are contained in the discharge gas of the second fluidized bed type furnace 320 are captured by the second cyclone 350, and are circulated by opening a second two-way valve 352 toward the second fluidized bed type furnace 320 at the initial operation stage. However, at the normal operation stage at which the fluidizing bed maintains a constant height within the furnace, the second two-way valve 352 is opened toward the third fine particle fluidized bed type furnace 330, so that the pre-reduced fine iron ore particles can be supplied to the third fluidized bed type furnace 330.
• the reduced fine iron ore particles are not circulated to the second fluidized bed type furnace 320, and thus, the fine iron ore particle capturing capability of the second cyclone 350 is improved, thereby making it possible to efficiently remove the fine particles from the discharge gas. Meanwhile, the intermediate/coarse iron ores which have not been flown away at the second fluidized bed type furnace 320 are finally reduced and outputted to the melter-gasifier 380 by which they are melt-reduced into a pig iron.
• the fine iron ore particles which have been captured by the first and second cyclones 340 and 350 and which have been supplied into the third fine particle fluidized bed type furnace 330 are finally reduced by the discharge gas of the melter-gasifier 380, which is supplied through the third reducing gas supplying pipe 372. If this reducing gas (discharge gas) does not attain to the target temperature, then oxygen is injected to raise the temperature, thereby adjusting the temperature of the third fluidized bed type furnace 330.
• the fine particles which are contained in the discharge gas of the third fluidized bed type furnace 330 are captured by the third cyclone 360 to be circulated to the third fluidized bed type furnace 330.
• the reduced fine iron particles which are discharged from the third fine particle fluidized bed type furnace 330 are supplied into the melter-gasifier 380 together with oxygen by the help of the melting burner 335. Thus they are not flown away from the melter-gasifier 380, but are dropped to be manufactured into a molten pig iron.
• the discharge gas (to be used as a reducing gas) of the melter-gasifier 380 is distributed to the second and third fluidized bed type furnaces 320 and 330, while the flow rates of this discharge gas are adjusted by the flow rate adjusting valves 375 and 377. Meanwhile, the gas flow velocity within the first and second fluidized bed type furnaces 310 and 320 should be preferably 1.5 - 1.7 times as fast as the minimum fluidizing velocity of the iron ore particles which stay within the f rnaces. In this manner, the reduction of the particles can be efficiently carried out, as well as promoting their movements .
• the gas flow velocity within the third fluidized bed type furnace 330 should be preferably 1.3 - 1.5 times as fast as the minimum fluidizing velocity of the iron ore particles which stay within the furnace, this velocity range being the optimum velocity of the bubble fluidizing bed.
• the internal reducing gas temperature of the fluidized bed of the first fluidized bed type furnace 310 should be preferably 750 - 800°C for an efficient iron ore reduction.
• the reducing gas temperature of the fluidized bed of the second and third fluidized bed type furnace 320 and 330 should be preferably 840 - 860°C.
• the fine iron ore particles which have been flown from the first fluidized bed type furnace 410 are supplied through the first circulating pipe 415 into the second fine particle fluidized bed type furnace 420.
• This fine particles form a bubble fluidizing bed together with the reducing gas incoming through the bottom of the furnace, so as to be reduced for a first time.
• the extremely fine iron ore particles which have been flown contained in the discharge gas of the second fine particle fluidized bed type furnace 420 are separated from the discharge gas by the first cyclone 440, and are circulated through the second and first circulating pipes 441 and 415 to the second fine particle fluidized bed type furnace 420.
• the gas 440 is finally discharged through the second discharge gas discharging pipe 443 to the outside, while the rest is circulated through the discharge gas circulating pipe 461 to the gas reforming system 460 depending on needs.
• the gas is supplied through the reformed gas supplying pipe 462 to the first and second fluidized bed type furnaces 410 and 420.
• the iron ores which have been reduced for a first time by the first and second fluidized bed type furnaces 410 and 420 are supplied through the first and second discharging pipes 411 and 421 to the third fluidized bed type furnace 430 so as to be reduced for a second time by a reducing gas by forming a bubble fluidizing bed.
• the extremely fine iron ore particles which have been flown contained in the discharge gas of the third fluidized bed type furnace 430 are separated from the discharge gas by the second cyclone 450. A part of them is circulated through the circulating pipe 451, the rotary gate 452 and the third circulating pipe 454 to the third fluidized bed type furnace 430, while the rest of them are supplied through the circulating pipe 451, the rotary gate 452, the third discharging pipe 455 and the fourth circulating pipe 482 to the melter-gasifier 480 or the outside.
• the discharge gas which has been separated from the fine iron ore particles by the second cyclone 450 is supplied as a reducing gas through the fourth discharge gas discharging pipe 453 to the first and second fluidized bed type furnaces 410 and 420 to form a fluidizing bed there.
• the iron ore which has been reduced for a second time by the third fluidized bed type furnace 430 is either discharged through the fourth discharging pipe 431 to the outside, or is supplied to the melter-gasifier 480 to be melted so as to be manufactured into a pig iron.
• the extremely fine iron ore particles which have been flown contained in the discharge gas of the melter-gasifier 480 are separated from the discharge gas by the third cyclone 484 to be circulated through the fourth circulating pipe 482 back to the melter-gasifier 480.
• the discharge gas which has been separated from the fine iron ore particles is supplied through the third reducing gas supplying pipe 436 to the third fluidized bed type furnace 430 as a reducing and fluidizing gas.
• the gas flow velocity within the first fluidized bed type furnace 410 should be preferably 1.2 - 3.5 times as fast as the minimum fluidizing velocity of the iron ore particles which stay within the furnace. In this manner, the reduction of the intermediate/coarse particles can be efficiently carried out, as well as promoting their movements .
• the gas flow velocity within the second and third fluidized bed type furnaces 420 and 430 should be preferably 1.2 - 2.5 times as fast as the minimum fluidizing velocity of the iron ore particles which stay within the furnaces .
• the intermediate/coarse iron ore particles which have been first-reduced by the first fluidized bed type furnace 410 are supplied into the third fluidized bed type furnace 430 through the first discharging pipe 411 which extends to the middle level of the fluidizing bed of the third fluidized bed type furnace 430.
• the fine iron ore particles which have been first-reduced by the second fluidized bed type furnace 420 are supplied to the third fluidized bed type furnace 430 through the second discharging pipe 421 which extends to the bottom of the fluidizing bed of the third fluidized bed type furnace 430. That is, the supplying positions of the fine and intermediate/coarse iron ore particles are different. The reason for this is as follows.
• the fine iron ore particles are supplied to a position same as that of the intermediate/coarse particles, then they cannot have a sufficient staying time within the third fluidized bed type furnace 430, but can be flown away. Therefore, the supplying position for the fine iron ore particles is made lower than that of the intermediate /coarse iron ore particles, so that the fine iron particles can have a sufficient staying time for a second reduction.
• the intermediate/coarse iron ore particles which have been second-reduced by the third fluidized bed type furnace 430 are transferred to the screw conveyor 435 which is disposed below the third fluidized bed type furnace 430, so as to be supplied through the fourth discharging pipe 431 to the melter-gasifier 480.
• the fine iron ore particles which have been second-reduced by the third fluidized bed type furnace 430 and flown therefrom are separated from the discharge gas by the second cyclone 450. A part of them is circulated to the third fluidized bed type furnace 430, while the rest are supplied through the third discharging pipe 455 to the melter-gasifier 480.
• the third discharging pipe 455 is connected to the fourth circulating pipe 482 which circulates the fine iron ore particles (which have been flown from the melter-gasifier 480 and captured by the third cyclone 484) back to the melter-gasifier 480.
• the fine iron ore particles and the intermediate/coarse iron ore particles are separately reduced, and they are charged separately. Therefore, the fine particle capturing capabilities of the cyclones are improved, thereby minimizing the elutriation loss of the fine iron ore particles .
• FIGs. 2, 3 and 4 illustrate two-stage fluidized bed type reducing apparatuses, but the present invention is not limited to the two-stage apparatus, but can cover a three-stage apparatus and multi-stage apparatuses.
• the pre-reducing apparatus of FIG. 2 was used, and the sizes of the fluidized bed type furnaces were as shown in Table 1.
• the chemical composition and the particle size distribution were as shown in Tables 2 and 3, and the conditions of Tables 4 and 5 were adopted in carrying out the reducing experiments .
• the dust content was greatly decreased by passing through the third fine particle fluidized bed type furnace, thereby drastically reducing the elutriation loss of the iron ore particles.
• the gas utilization rate was 30 - 35%, and the gas consumption rate was 1300 - 1500 Nm 3 /ton-ore.
• the iron ore particles which were supplied from the conical first fluidized bed type furnace to the conical second fluidized bed type furnace showed a reduction rate of 30 - 40%, while the reduced iron particles which were supplied from the second fluidized bed type furnace to the melter- gasifier showed a reduction rate of 80 - 85%.
• the fine iron particles which were discharged from the third fluidized bed type furnace showed a reduction rate as high as about 90%. Thus it was seen that the reduction rate was further improved by employing the third fluidized bed type furnace.
• the fine iron ore particles and the intermediate/coarse iron ore particles are separately reduced, and therefore, the fine particle treating loads of the cyclones are alleviated, thereby improving the fine particle removing capabilities. Therefore, a fine iron ore having a wide particle size distribution can be reduced more efficiently with a less elutriation loss.

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• 1998
  • 1998-12-09 KR KR1019980053955A patent/KR100321050B1/ko not_active IP Right Cessation
• 1999
  • 1999-12-03 BR BR9907794A patent/BR9907794A/pt not_active Application Discontinuation
  • 1999-12-03 AU AU15132/00A patent/AU1513200A/en not_active Abandoned
  • 1999-12-03 EP EP19990957428 patent/EP1055006A1/de not_active Withdrawn
  • 1999-12-03 WO PCT/KR1999/000729 patent/WO2000034531A1/en not_active Application Discontinuation
  • 1999-12-03 JP JP2000586963A patent/JP2002531705A/ja active Pending
  • 1999-12-03 CA CA 2320242 patent/CA2320242A1/en not_active Abandoned
• 2000
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