SE2350304A1 - A method for the production of carburized sponge iron - Google Patents
A method for the production of carburized sponge ironInfo
- Publication number
- SE2350304A1 SE2350304A1 SE2350304A SE2350304A SE2350304A1 SE 2350304 A1 SE2350304 A1 SE 2350304A1 SE 2350304 A SE2350304 A SE 2350304A SE 2350304 A SE2350304 A SE 2350304A SE 2350304 A1 SE2350304 A1 SE 2350304A1
- Authority
- SE
- Sweden
- Prior art keywords
- gas
- shaft
- level
- carburising
- carburisation
- Prior art date
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Classifications
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0073—Selection or treatment of the reducing gases
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- 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
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- 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
- C21B13/004—Making spongy iron or liquid steel, by direct processes in a continuous way by reduction from ores
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- 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
- C21B2100/26—Increasing the gas reduction potential of recycled exhaust gases by adding additional fuel in recirculation pipes
-
- 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
- C21B2100/28—Increasing the gas reduction potential of recycled exhaust gases by separation
- C21B2100/282—Increasing the gas reduction potential of recycled exhaust gases by separation of carbon dioxide
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- 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
- C21B2100/60—Process control or energy utilisation in the manufacture of iron or steel
- C21B2100/64—Controlling the physical properties of the gas, e.g. pressure or temperature
-
- 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
- C21B2100/60—Process control or energy utilisation in the manufacture of iron or steel
- C21B2100/66—Heat exchange
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Dispersion Chemistry (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
- Manufacture Of Iron (AREA)
Abstract
An arrangement for the production of sponge iron by direct reduction of iron ore, said arrangement comprising a direct reduction shaft (1), a reduction gas inlet (5), provided at a first level (L1) in the direct reduction shaft (1), a carburisation shaft (7), a material feed conduit (8) extending from the bottom outlet (3) of the direct reduction shaft (1) to the carburisation shaft (7), which has a carburising gas inlet (9) and a carburising gas source (11) connected to said gas inlet (9), and a valve (12) for controlling a flow of carburising gas from the carburising gas source (11) into the carburisation shaft (7) through the carburising gas inlet (9). A gas sensor (13) is provided to measure a content of the carburising gas in the direct reduction shaft (1). A control unit (14) is configured to control the flow rate of the carburising gas introduced into the carburisation shaft (7) on basis of the determined content of carburising gas at said second level (L2) by controlling said valve (12), such that the content of carburising gas at said second level (L2) is within a predetermined range.
Description
A method for the production of carburized sponge iron TECHNICAL FIELD The present invention relates to a method for the production of carburized sponge iron, the method comprising the steps of: -introducing pelletized iron ore into an iron ore inlet provided at an upper part of a vertically arranged direct reduction shaft, and allowing the pelletized iron ore to flow downwards through the direct reduction shaft towards a bottom outlet, -introducing a reduction gas at predetermined first level of the direction reduction shaft, thereby generating a flow of reduction gas in a direction opposite to the flow direction of the pelletized iron ore such that the iron ore is reduced to sponge iron before reaching the bottom outlet of the direct reduction shaft, -removing spent reduction gas through a gas outlet provided at an upper part of the direct reduction shaft, -transferring the sponge iron via a material feed conduit from the bottom outlet of the direct reduction shaft to a carburisation shaft, wherein the material feed conduit permits the passage of solids and gases between the direct reduction shaft and the carburisation shaft; -introducing a carburising gas into the carburisation shaft via a gas inlet located distant from the material feed conduit, and -removing carburising gas from the carburisation shaft via a gas outlet located adjacent to the material feed conduit.
The invention also relates to a corresponding arrangement for the production of carburized sponge iron.
BACKGROUND ln connection to the production of sponge iron by a process in which hydrogen gas is primarily used as the reduction gas, the sponge iron will have a very low carbon content. A low carbon content may make the sponge iron more reactive and may also be less favourable in connection to a subsequent melting process, for example in an electric arc furnace, in which the carbon may contribute to better melting conditions, such as lower melting temperature. Therefore, it has been suggested to subject the sponge iron to a carburising gas, in order to increase the carbon content in the sponge iron.
Using a separate carburisation shaft, which is connected to the reduction shaft through a material feed conduit may be advantageous, since it opens for larger versatility in terms of control of the flow of the carburising gas and prevention of carburising gas slip into the reduction zone, but also in terms of design versatility. The carburization shaft may be used also as a cooling shaft, for the purpose of providing cooled direct reduced iron, DRI, pellets. A line parallel to the carburisation shaft may be arranged, in which hot DRI pellets are fed directly from the bottom outlet of the reduction shaft into a briquetting machine in which they are pressed into hot briquette iron, also referred to as HBI. A valve arrangement may thus be provide that allows such change of line.
A problem encountered when applying a separate carburisation shaft is how to achieve as stable and efficient carburisation as possible, preferably without flaring off excessive carburising gas in the carburising gas loop generated in the carburisation shaft.
SUMMARY The object of the invention is achieved by means of a method for the production of carburized sponge iron, the method comprising the steps of: -introducing pelletized iron ore into an iron ore inlet provided at an upper part of a vertically arranged direct reduction shaft, and allowing the pelletized iron ore to flow downwards through the direct reduction shaft towards a bottom outlet, -introducing a reduction gas at predetermined first level of the direction reduction shaft, thereby generating a flow of reduction gas in a direction opposite to the flow direction of the pelletized iron ore such that the iron ore is reduced to sponge iron before reaching the bottom outlet of the direct reduction shaft, -removing spent reduction gas through a gas outlet provided at an upper part of the direct reduction shaft, -transferring the sponge iron via a material feed conduit from the bottom outlet of the direct reduction shaft to a carburisation shaft, wherein the material feed conduit permits the passage of solids and gases between the direct reduction shaft and the carburisation shaft; -introducing a carburising gas into the carburisation shaft via a gas in|et located distant from the material feed conduit, and -removing carburising gas from the carburisation shaft via a gas outlet located adjacent to the material feed conduit, the method being characterised in that it comprises the steps of: - determining, at a second level in the direct reduction shaft, the content of carburising gas, and -controlling the flow rate ofthe carburising gas introduced into the carburisation shaft on basis of the determined content of carburising gas at said second level, such that the content of carburising gas at said second level is within a predetermined range.
The invention enables a deliberate use of lower parts of the reduction shaft for carburisation purposes. A deliberate and controlled slip of carburising gas from the carburisation shaft into the reduction shaft thereby promotes efficient carburisation. The controlled slip of carburising gas into the reduction shaft may also contribute to less need of flaring off excessive carburising gas from the carburisation loop in the carburisation shaft.
According to one embodiment, the carburising gas introduced into the carburisation shaft comprises the gas removed from the carburisation shaft and additional fresh gas, wherein the flow rate of the additional fresh gas is controlled such that the content of carburising gas at said second level is within said predetermined range.
According to one embodiment, the chemical composition of the gas removed from the carburisation shaft is measured, and the composition of the additional fresh gas is controlled on basis of the measured chemical composition of the gas removed from the carburisation shaft.
According to one embodiment, a content of CO and CH4 in the gas removed from the carburisation shaft is measured, and the content of CO and CH4 in the additional fresh gas is controlled such that the content of CO and CH4 in the carburising gas introduced into the carburisation shaft is within a predetermined range.
According to one embodiment, the content of CO and H2 in the gas introduced into the carburisation shaft is: CO/H2<1:3 (molar ratio).
According to one embodiment, the carburising gas introduced into the carburisation shaft via the gas in|et has the following composition (mole%): H2: 30-65% CO: 0-10% H20: 0-1 .5% CO2: 0-1 .5% N2: 0-10% CH4 20-50% C2H6: 0-3% According to one embodiment, the carburising gas introduced into the carburisation shaft via the gas in|et has the following composition (mole%): H2: 50-65% CO: 0-5% H20: 0-1.5% CO2: 0-1.5% N2: 0-10% CH4: 20-35% C2H6: 0-3%.
According to one embodiment, the direct reduction shaft has an inner volume V1 defined by its inner wall, the predetermined first level at which the reduction gas is introduced and the bottom outlet, wherein at least 50% of said volume V1 is located below the second level. lt should be avoided to have carburising gas slipping up to and above the first level. Therefore, the second level should not be too far away from the first level, in order enable a good view of the carbon content at the first level on basis of measurement at the second level. According to one embodiment at least 75% of said volume V1 is located below the second level. The carburising gas content may differ in the radial direction of the reduction shaft, and is typically higher in the centre thereof. lfa gas analysis sensor is used for measuring the carburising gas content at the second level, the position of the sensor and the results obtained therefrom should be combined with the knowledge of how the radial variation of the carburising gas content (and maybe also the temperature in the reduction shaft) in order to determine the predetermined range to be obtained at the second level, such that slip into the reduction zone, i.e. above the first level, is prevented. Preferably, prediction of a carburising gas distribution in the reduction shaft, based on previous, detailed measurements of carburising content in the reduction shaft and, possibly, excavation results of stopped processes in which the carburising gas distribution has been studied, could be used in order to establish a predicted carburising gas distribution on basis of the determination of the carburising gas content at the second level.
According to one embodiment, the second level is below or at the same level as the first level.
According to one embodiment, at least 10% of the volume V1 is above the second level. Measurements too close to the first level will necessarily be affected by the large reduction gas flow, and will thus be less precise. Therefore, measuring and determining the carburising gas flow somewhat below the first level will result in better precision.
According to one embodiment, the lower limit of said predetermined range is above 0%. lf the lower limit is too low, the measurement does not tell anything about the content below the second level. lf the content is zero at the second level, it might be zero all way down to the carburisation shaft. Thus the lower limit should be above zero, indicating that carburisation is taking place at least up to the second level.
According to one embodiment, the direct reduction shaft has an inner volume V1 defined by its inner wall, the predetermined first level at which the reduction gas is introduced and the bottom outlet, wherein the lower limit of said predetermined range is a content of carburising gas at which carburisation of the sponge iron will take place in at least 50%, preferably in at least 60,%, and more preferably in at least 75% of said volume V. lt is preferred to use as much of the volume V1 as possible for carburising purposes, however preferably without any substantial slip of carburising gas into the reduction zone, i.e. above the first level.
According to one embodiment, the upper limit of said predetermined range is a content of carburising gas at which essentially all carburising gas will be consumed through carburisation before reaching said predetermined first level. ln other words, the flow rate of added carburising gas is controlled on basis of the determined content of carburising gas at the second level such that essentially no carburising gas from the carburisation shaft is permitted to slip up into the reduction zone.
According to one embodiment, the determination of the content of carburising gas at the second level is performed by measurement of said content at said second level by means of a sensor positioned in the direct reduction shaft at said second level. According to one embodiment, the measurement is done at the inner periphery of the reduction shaft. However, the measurement may alternatively be performed closer to or at a longitudinal centre line of the reduction shaft, where the concentration of carburising gas is assumed to be higher or even highest.
According to one embodiment, the method comprises the step of determining, at a third level in the direct reduction shaft, the content of carburising gas, wherein the third level is below the second level, and controlling the flow rate of the carburising gas introduced into the carburisation shaft on basis of the determined content of carburising gas at said second level and on basis of the determined content of carburising gas at said third level. Measuring at more levels than only the second level will improve the preciseness of a possible prediction of the carburising gas distribution in the reduction shaft, and is thus preferred. As an alternative, the third level may be above the first level. ln such a case, the flow rate of the carburising gas introduced into the carburisation shaft should be controlled so that the content of carbon at the third level is zero.
According to one embodiment, the inner wall of the direct reduction shaft defines a truncated cone from said predetermined first level to its bottom outlet, the diameter of the truncated cone decreasing towards the bottom outlet.
According to one embodiment, the direct reduction shaft has an inner volume V1 defined by its inner wall, the predetermined first level at which the reduction gas is introduced and the bottom outlet, and the carburisation shaft has a volume V2 defined by its inner wall, the level of the gas inlet for introduction of carburisation and the level of the gas outlet for removal of carburising gas from the carburisation shaft, wherein 0.5 According to one embodiment, the carburising gas introduced into the carburisation shaft via the gas inlet has the following composition in (mole%): H2: 30-65% CO: 0-10% H20: 0-1.5% C02: 0-1 .5% N2: 0-10% CH4 20-50% C2H6: 0-3% According to one embodiment, the carburising gas introduced into the carburisation shaft via the gas inlet has the following composition in (mole%): H2: 50-65% CO: 0-5% H20: 0-1.5% C02: 0-1.5% N2: 0-10% CH4: 20-35% C2H6: O-3% According to one embodiment, the reduction gas introduced into the direction reduction shaft at said first predetermined level comprises at least 96 mole% H2.
The object of the invention is also achieved by means of an arrangement for the production of sponge iron by direct reduction of iron ore, said arrangement comprising: - a vertically arranged direct reduction shaft comprising an iron ore in|et provided at an upper part of the reduction shaft, and a bottom out|et for removal of produced sponge iron, - a reduction gas source, - a reduction gas in|et, provided at a first level in the direct reduction shaft, - a gas out|et provided at an upper part of the direct reduction shaft, for removal of off-gas from the direct reduction shaft, -a carburisation shaft, - a material feed conduit extending from the bottom out|et of the direct reduction shaft to the carburisation shaft, wherein the material feed conduit permits the passage of solids and gases between the direct reduction shaft (1) and the carburisation shaft; - the carburisation shaft having a carburising gas in|et located distant from the material feed conduit and a gas out|et located adjacent to the material feed conduit, - a carburising gas source connected to said gas in|et, and - a valve for controlling a flow of carburising gas from the carburising gas source into the carburisation shaft through the carburising gas in|et, said arrangement being characterised in that it comprises - a gas sensor provided at a second level in the direct reduction shaft, said gas sensor being configured to measure a content of the carburising gas in the direct reduction shaft, and - a control unit configured to control the flow rate of the carburising gas introduced into the carburisation shaft on basis of the determined content of carburising gas at said second level by controlling said valve, such that the content of carburising gas at said second level is within a predetermined range.
According to one embodiment, the arrangement comprises a sensor for sensing the composition of gas removed from the carburisation shaft via the gas outlet located adjacent to the material feed conduit, and means for affecting the composition of the gas from the carburising gas source, wherein the control unit is configured to control the means for affecting the composition of the gas from the carburising gas source on basis of information from the sensor for sensing the composition of gas removed from the carburisation shaft via the gas outlet located adjacent to the material feed conduit.
According to one embodiment, the arrangement comprises a gas conduit extending from the gas outlet located adjacent to the material feed conduit to said carburising gas inlet.
According to one embodiment, the arrangement comprises a second a gas sensor provided at a third level in the direct reduction shaft, said sensor being configured to measure a content of the carburising gas in the direct reduction shaft, wherein the third level is below the second level, and wherein the control unit is configured to control the flow rate of the carburising gas introduced into the carburisation shaft on basis of the determined content of carburising gas at said second level and on basis of the determined content of carburising gas at said third level.
BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows an embodiment of an arrangement according to the present invention for the production of carburized sponge iron DETAILED DESCRIPTION Fig. 1 shows an arrangement for the production of sponge iron by direct reduction of iron ore. The arrangement comprises a vertically arranged direct reduction shaft 1 comprising an iron ore inlet 2 provided at an upper part of the reduction shaft 1, and a bottom outlet 3 for removal of produced sponge iron. The arrangement further comprises a reduction gas source 4, a reduction gas inlet 5 , provided at a first level L1 in the direct reduction shaft 1, and a top gas outlet 6 provided at an upper part of the direct reduction shaft 1, for removal of off-gas from the direct reduction shaft 1.
The inner wall of the direct reduction shaft 1 defines a truncated cone from said predetermined first level L1 to its bottom outlet 3, the diameter of the truncated cone decreasing towards the bottom outlet 3.
A main reduction gas conduit 22 extends from the reduction gas source 4 to the reduction gas inlet 5, and a top gas conduit 23 extends from the top gas outlet 6 to the main reduction gas conduit 22. A gas cleaning arrangement 24 forms part of the top gas conduit 23, and a heater 25 forms part of the main reduction gas conduit 22, for the purpose of heating both the gas recycled via the top gas conduit 22 and the fresh reduction gas delivered by the reduction gas source 4.
The arrangement also comprises a carburisation shaft 7, and a material feed conduit 8 extending from the bottom outlet 3 of the direct reduction shaft 1 to the carburisation shaft 7. The material feed conduit 8 permits the passage of solids and gases between the direct reduction shaft 1 and the carburisation shaft 7. The carburisation shaft 7 has a carburising gas inlet 9 located distant from the material feed conduit 8 and a gas outlet 10 located adjacent (closer than the gas inlet 9) to the material feed conduit 8. A carburising gas source 11 is connected to said gas inlet 9. There is also provided a valve 12 for controlling a flow of carburising gas from the carburising gas source 11 into the carburisation shaft 7 through the carburising gas inlet 9.
The arrangement further comprises a gas sensor 13 provided at a second level L2 in the direct reduction shaft 1, said sensor 13 being configured to measure a content of the carburising gas in the direct reduction shaft 1. There is also provided a control unit 14 configured to control the flow rate of the carburising gas introduced into the carburisation shaft 1 on basis of the determined content of carburising gas at said 11 second level L2 by controlling said valve 12, such that the content of carburising gas at said second level L2 is within a predetermined range.
The direct reduction shaft 1 has an inner volume V1 which is only a part of the total volume of the direction reduction shaft 1 and which is defined by the inner wall of the shaft, the predetermined first level L1 at which the reduction gas is introduced and the level of the bottom outlet 3, wherein at least 50% of said volume V1 is located below the second level L2. ln the embodiment shown, the second level L2 is below the first level L1. ln the embodiment shown, approximately 25% of the volume V1 is above the second level.
The carburisation shaft has a volume V2 defined by its inner wall, the level of the gas inlet 9 for introduction of carburisation gas and the level of the gas outlet 10 for removal of carburising gas from the carburisation shaft. According to an exemplifying embodiment disclosed herein V1N2 =1.
The arrangement further comprises a sensor 15 for sensing the composition of gas removed from the carburisation shaft 7 via the gas outlet 10 located adjacent to the material feed conduit 8. There are also provided means 16-19 for affecting the composition of the gas from the carburising gas source 11, wherein the control unit 14 is configured to control the means 16-19 for affecting the composition of the gas from the carburising gas source 11 on basis of information from the sensor 15 for sensing the composition of gas removed from the carburisation shaft 7 via the gas outlet 10 located adjacent to the material feed conduit 8. The means 16-18 for affecting the composition of the gas comprise a carbon monoxide, CO, source 16 and a methane, CH4, source 17 and valves 18, 19 for controlling addition of CO and CH4 to the carburising gas from the gas source 11.
A gas conduit 20 extends from the gas outlet 10 located adjacent to the material feed conduit to said carburising gas inlet 9. The carburising gas source 11 and the means 16 for affecting the composition of the gas from the carburising gas source 11 are connected to said gas conduit 19. A carburising gas loop is thereby defined 12 in which carburising gas, added with fresh gas from the gas source 11 and said means 16, circulates through the carburisation shaft 7 and the gas conduit 9.
The arrangement further comprises a second a gas sensor 21 provided at a third level L3 in the direct reduction shaft 1. Also the second gas sensor 21 is configured to measure a content of the carburising gas in the direct reduction shaft, wherein the third level L3 is below the second level L2, and wherein the control unit 14 is configured to control the flow rate of the carburising gas introduced into the carburisation shaft 7 on basis of the determined content of carburising gas at said second level L2 and on basis of the determined content of carburising gas at said third level L3.
The arrangement, in particular the control unit 14 in combination with and in cooperation with the above-mentioned sensors, is configured to control the composition of and the flow rate of the carburising gas introduced into the carburisation shaft 7 in accordance with the an embodiment of the method of the invention which is to be disclosed hereinafter.
The method comprises the steps of: -introducing pelletized iron ore into the iron ore inlet 2 and allowing the pelletized iron ore to flow downwards through the direct reduction shaft towards the bottom outlet 3; -introducing a reduction gas at the first level L1, thereby generating a flow of reduction gas in a direction opposite to the flow direction of the pelletized iron ore such that the iron ore is reduced to sponge iron before reaching the bottom outlet 3 of the direct reduction shaft 1; -removing spent reduction gas through the top gas outlet 6; -transferring the sponge iron via a material feed conduit 8 from the bottom outlet 3 of the direct reduction shaft 1 to the carburisation shaft 7; -introducing the carburising gas into the carburisation shaft 7 via the gas inlet 9 located distant from the material feed conduit 8; and 13 -removing gas from the carburisation shaft 7 via the gas outlet 10 located adjacent to the material feed conduit 8, and conducting the gas back to the gas inlet 9 through the gas conduit 20.
The method further comprises the steps of: - determining, at the second level L2, the content of carburising gas, and -contro||ing the flow rate ofthe carburising gas introduced into the carburisation shaft 7 on basis of the determined content of carburising gas at said second level L2, such that the content of carburising gas at said second level L2 is within a predetermined range.
The carburising gas introduced into the carburisation shaft 7 comprises the gas removed from the carburisation shaft 7 and additional fresh gas from the carburising gas source 11, and possibly from the means 16-19 for affecting the composition of the gas. The flow rate of the additional fresh gas (including the contribution by the means 16-19) is controlled such that the content of carburising gas at said second level is within said predetermined range.
The chemical composition of the gas removed from the carburisation shaft is measured, and the composition of the additional fresh gas is controlled, by means of the control unit 14 and the means 16, on basis of the measured chemical composition of the gas removed from the carburisation shaft 7.
The content of CO and CH4 in the gas removed from the carburisation shaft is measured, and the content of CO and CH4 in the additional fresh gas is controlled, by addition from the means 16, such that the content of CO and CH4 in the carburising gas introduced into the carburisation shaft 7 is within a predetermined range.
The content of CO and H2 in the gas introduced into the carburisation shaft 7 is: CO/H2<1:3 (molar ratio). According to an exemplifying embodiment disclosed here, CO/H2 = 3:63 14 According to one embodiment, the carburising gas introduced into the carburisation shaft via the gas inlet has the following composition (mole%): H2: 63 % CO: 3 % H20: 1 % C02: 1% N2: 5 % CH4: 27% C2H6: 2%.
The lower limit of said predetermined range is above 0%. According to an exemplifying embodiment disclosed here, the lower limit is 2%.
The lower limit of said predetermined range is a content of carburising gas at which carburisation of the sponge iron will take place in at least 50%, preferably in at least 60,%, and more preferably in at least 75% of said volume V1. On basis of prior data about correlation between the content of the carburising gas at the second level and the degree to which carburisation takes place in said volume, the upper limit of said predetermined range may be chosen such that carburisation will take place to maximum extent in said volume V1 without slip of carburising gas to the reduction zone above the first level L1. 100% use of the volume V1 for carburisation might not be possible, since there may be differences in gas content in the radial direction of the shaft. Typically, the gas content is higher towards the longitudinal centre line of the shaft 1 in said volume V1, meaning that use of peripheral upper parts of the volume V1 for carburisation purposes might not be possible without at the same time allowing slip of gas into the reduction zone, i.e. above the first level L1.
The upper limit of said predetermined range is a content of carburising gas at which essentially all carburising gas will be consumed through carburisation before reaching said predetermined first level L1.
The method also comprises the step of determining, at the third level L3, the content of carburising gas and controlling the flow rate of the carburising gas introduced into the carburisation shaft on basis of the determined content of carburising gas at said second level L2 and on basis of the determined content of carburising gas at said third level L3. This may be achieved in practice by contro||ing the flow rate of the carburising gas introduced into the carburisation shaft also on basis of the determined content of carburising gas at said third level L3, such that the content of carburising gas at said second level L2 is within a predetermined range. The predetermined range with regard to the measurement at the third level may be determined on basis of prior data about correlation between the content of the carburising gas at the third level L3 and the degree to which carburisation takes place in said volume V1. Still, the upper limit should be low enough to prevent local, typically central, slip of carburising gas into the reduction zone, i.e. above the first level L1.
According to an exemplifying embodiment disclosed here, the reduction gas introduced into the direction reduction shaft at said first predetermined level comprises 99 mole% H2.
Claims (22)
1. A method for the production of carburized sponge iron, the method comprising the steps of: -introducing pelletized iron ore into an iron ore in|et (2) provided at an upper part of a vertically arranged direct reduction shaft (1), and allowing the pelletized iron ore to flow downwards through the direct reduction shaft (1 ) towards a bottom outlet (3), -introducing a reduction gas at predetermined first level (L1) of the direction reduction shaft, thereby generating a flow of reduction gas in a direction opposite to the flow direction of the pelletized iron ore such that the iron ore is reduced to sponge iron before reaching the bottom outlet (3) of the direct reduction shaft (1 ), -removing spent reduction gas through a gas outlet (6) provided at an upper part of the direct reduction shaft (1 ), -transferring the sponge iron via a material feed conduit from the bottom outlet (3) of the direct reduction shaft (1 ) to a carburisation shaft (7), wherein the material feed conduit (8) permits the passage of solids and gases between the direct reduction shaft (1) and the carburisation shaft (7); -introducing a carburising gas into the carburisation shaft via a gas in|et (9) located distant from the material feed conduit (8), and -removing carburising gas from the carburisation shaft (1) via a gas outlet (10) located adjacent to the material feed conduit (8), the method being characterised in that it comprises the steps of: - determining, at a second level (L2) in the direct reduction shaft, the content of carburising gas, and -controlling the flow rate ofthe carburising gas introduced into the carburisation shaft (7) on basis of the determined content of carburising gas at said second level (L2), such that the content of carburising gas at said second level (L2) is within a predetermined range.
2. A method according to claim 1, wherein the carburising gas introduced into the carburisation shaft (7) comprises the gas removed from the carburisation shaft (7) and additional fresh gas, wherein the flow rate of the additional fresh gas iscontrolled such that the content of carburising gas at said second level (L) is within said predetermined range.
3. A method according to claim 1 or 2, wherein the chemical composition of the gas removed from the carburisation shaft (7) is measured, and wherein the composition of the additional fresh gas is controlled on basis of the measured chemical composition of the gas removed from the carburisation shaft (7).
4. A method according to claim 3, wherein a content of CO and CH4 in the gas removed from the carburisation shaft is measured, and wherein the content of CO and CH4 in the additional fresh gas is controlled such that the content of CO and CH4 in the carburising gas introduced into the carburisation shaft (7) is within a predetermined range.
5. A method according to claim 3 or 4, wherein the content of CO and H2 in the gas introduced into the carburisation shaft (7) is: CO/H2<1:3 (molar ratio).
6. A method according to any one of claims 1-5, wherein the carburising gas introduced into the carburisation shaft (7) via the gas inlet (9) has the following composition (mole%): H2: 30-65%, CO: 0-10%, H20: 0-1 .5%, CO2: 0-1 .5%, N2: 0-10%, CH4 20-50%, C2H6: 0-3%.
7. A method according to any one of claims 1-6, wherein the direct reduction shaft has an inner volume (V1) defined by its inner wall, the predetermined first level (L1 ) at which the reduction gas is introduced and the bottom outlet (3), wherein at least 50% of said volume (V1) is located below the second level (L2).
8. A method according to any one of claims 1-7, wherein the second level (L2) is below or at the same level as the first level (L1).
9. A method according to any of claims 1-8, wherein at least 10% of the volume (V1) is above the second level (L2).
10. A method according to any one of claims 1-9, wherein the lower limit of said predetermined range is above 0%.
11. A method according to any one of claims 1-10, wherein the direct reduction shaft has an inner volume (V1) defined by its inner wall, the predetermined first level (L1) at which wherein the lower limit of said predetermined range is a content of carburising gas the reduction gas is introduced and the bottom outlet (3), at which carburisation of the sponge iron will take place in at least 50%, preferably in at least 60,%, and more preferably in at least 75% of said volume (V1).
12. A method according to any one of claims 1-11, wherein the upperlimit of said predetermined range is a content of carburising gas at which essentially all carburising gas will be consumed through carburisation before reaching said predetermined first level (L1).
13. A method according to any one of claims 1-12, wherein the determination of the content of carburising gas at the second level (L2) is performed by measurement of said content at said second level by means of a sensor (13) positioned in the direct reduction shaft (1) at said second level (L2).
14. A method according to any one of claims 1-13, comprising the step of determining, at a third level (L3) in the direct reduction shaft (1), the content of carburising gas, wherein the third level (L3) is below the second level (L2), and controlling the flow rate of the carburising gas introduced into the carburisation shaft (7) on basis of the determined content of carburising gas at said second level (L2) and on basis of the determined content of carburising gas at said third level (L3).
15. A method according to any one of c|aims 1-14, wherein the inner wall of the direct reduction shaft (1 ) defines a truncated cone from said predetermined first level (L1) to its bottom outlet (3), the diameter of the truncated cone decreasing towards the bottom outlet (3).
16. A method according to any one of c|aims 1-15, wherein the direct reduction shaft has an inner volume (V1) defined by its inner wall, the predetermined first level (L1) at which the reduction gas is introduced and the bottom outlet (3), and wherein the carburisation shaft (7) has a volume (V2) defined by its inner wall, the level of the gas in|et for introduction of carburisation and the level of the gas outlet for removal of carburising gas from the carburisation shaft (7) and that 0.5
17. A method according to any one of c|aims 1-16, wherein the carburising gas introduced into the carburisation shaft (7) via the gas in|et has the following composition (mole%): H2: 30-65%, CO: 0-10%, H20: 0-1.5%, C02: 0-1.5%, N2: 0-10%, CH4 20-50%, C2H6: 0-3%.
18. A method according to any one of c|aims 1-17, wherein the reduction gas introduced into the direction reduction shaft at said first predetermined level (L1) comprises at least 96 mole% H
19. An arrangement for the production of sponge iron by direct reduction of iron ore, said arrangement comprising: - a vertically arranged direct reduction shaft (1) comprising an iron ore in|et (2) provided at an upper part of the reduction shaft (1), and a bottom outlet (3) for removal of produced sponge iron, - a reduction gas source (4), - a reduction gas inlet (5), provided at a first level (L1) in the direct reduction shaft (1), - a gas out|et (6) provided at an upper part of the direct reduction shaft (1), for removal of off-gas from the direct reduction shaft (1 ), -a carburisation shaft (7) - a material feed conduit (8) extending from the bottom out|et (3) of the direct reduction shaft (1) to the carburisation shaft (7), wherein the material feed conduit (8)permits the passage of solids and gases between the direct reduction shaft (1) and the carburisation shaft (7); - the carburisation shaft (7) having a carburising gas inlet (9) located distant from the material feed conduit and a gas out|et (10) located adjacent to the material feed conduit (8), - a carburising gas source (11) connected to said gas inlet (9), and - a valve (12) for controlling a flow of carburising gas from the carburising gas source (11) into the carburisation shaft (7) through the carburising gas inlet (9), said arrangement being characterised in that it comprises - a gas sensor (13) provided at a second level (L2) in the direct reduction shaft, said gas sensor (13) being configured to measure a content of the carburising gas in the direct reduction shaft (1 ), and - a control unit (14) configured to control the flow rate of the carburising gas introduced into the carburisation shaft (7) on basis of the determined content of carburising gas at said second level (L2) by controlling said valve (12), such that the content of carburising gas at said second level (L2) is within a predetermined range.
20. An arrangement according to claim 19, comprising a sensor (15) for sensing the composition of gas removed from the carburisation shaft (7) via the gas out|et (10) located adjacent to the material feed conduit (8), and means (16-19) for affecting the composition of the gas from the carburising gas source (11), wherein the control unit (14) is configured to control the means (16-19) for affecting the composition of the gas from the carburising gas source (11) on basis of information from the sensor (15) for sensing the composition of gas removed from thecarburisation shaft (7) via the gas outlet (10) located adjacent to the material feed conduit (8).
21. An arrangement according to claim 19 or 20, comprising a gas conduit (20) extending from the gas outlet (10) located adjacent to the material feed conduit (8) to said carburising gas inlet (9).
22. An arrangement according to any one of claims 19-21, comprising a second a gas sensor (21) provided at a third level (L3) in the direct reduction shaft (1 ), said sensor (21) being configured to measure a content of the carburising gas in the direct reduction shaft (1), and wherein the third level (L3) is below the second level (L2), and wherein the control unit (14) is configured to control the flow rate of the carburising gas introduced into the carburisation shaft (7) on basis of the determined content of carburising gas at said second level (L2) and on basis of the determined content of carburising gas at said third level (L3).
Priority Applications (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE2350304A SE546870C2 (en) | 2023-03-17 | 2023-03-17 | A method for the production of carburized sponge iron |
| AU2024240537A AU2024240537A1 (en) | 2023-03-17 | 2024-03-07 | A method for the production of carburized sponge iron |
| PCT/SE2024/050212 WO2024196294A1 (en) | 2023-03-17 | 2024-03-07 | A method for the production of carburized sponge iron |
| KR1020257033839A KR20250161005A (en) | 2023-03-17 | 2024-03-07 | Method for producing carbonized sponge iron |
| CN202480018276.4A CN120787265A (en) | 2023-03-17 | 2024-03-07 | Method for producing carburized sponge iron |
| MX2025010814A MX2025010814A (en) | 2023-03-17 | 2025-09-12 | A method for the production of carburized sponge iron |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE2350304A SE546870C2 (en) | 2023-03-17 | 2023-03-17 | A method for the production of carburized sponge iron |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| SE2350304A1 true SE2350304A1 (en) | 2024-09-18 |
| SE546870C2 SE546870C2 (en) | 2025-03-04 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| SE2350304A SE546870C2 (en) | 2023-03-17 | 2023-03-17 | A method for the production of carburized sponge iron |
Country Status (6)
| Country | Link |
|---|---|
| KR (1) | KR20250161005A (en) |
| CN (1) | CN120787265A (en) |
| AU (1) | AU2024240537A1 (en) |
| MX (1) | MX2025010814A (en) |
| SE (1) | SE546870C2 (en) |
| WO (1) | WO2024196294A1 (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016209298A1 (en) * | 2015-06-24 | 2016-12-29 | Midrex Technologies, Inc. | Methods and systems for increasing the carbon content of sponge iron in a reduction furnace |
| CN107858471A (en) * | 2017-12-01 | 2018-03-30 | 江苏省冶金设计院有限公司 | A kind of system and method for gas-based shaft kiln production sponge iron |
| US20210246521A1 (en) * | 2018-06-12 | 2021-08-12 | Primetals Technologies Austria GmbH | Method for Carburization of HDRI produced in H2 based Direct Reduction Process |
| SE2150742A1 (en) * | 2021-06-11 | 2022-12-12 | Hybrit Development Ab | Process for the production of carburized sponge iron |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE532975C2 (en) * | 2008-10-06 | 2010-06-01 | Luossavaara Kiirunavaara Ab | Process for the production of direct-reduced iron |
| SE546651C2 (en) * | 2020-05-04 | 2025-01-07 | Hybrit Development Ab | Process for the production of carburized sponge iron |
-
2023
- 2023-03-17 SE SE2350304A patent/SE546870C2/en unknown
-
2024
- 2024-03-07 KR KR1020257033839A patent/KR20250161005A/en active Pending
- 2024-03-07 AU AU2024240537A patent/AU2024240537A1/en active Pending
- 2024-03-07 WO PCT/SE2024/050212 patent/WO2024196294A1/en active Pending
- 2024-03-07 CN CN202480018276.4A patent/CN120787265A/en active Pending
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2025
- 2025-09-12 MX MX2025010814A patent/MX2025010814A/en unknown
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016209298A1 (en) * | 2015-06-24 | 2016-12-29 | Midrex Technologies, Inc. | Methods and systems for increasing the carbon content of sponge iron in a reduction furnace |
| CN107858471A (en) * | 2017-12-01 | 2018-03-30 | 江苏省冶金设计院有限公司 | A kind of system and method for gas-based shaft kiln production sponge iron |
| US20210246521A1 (en) * | 2018-06-12 | 2021-08-12 | Primetals Technologies Austria GmbH | Method for Carburization of HDRI produced in H2 based Direct Reduction Process |
| SE2150742A1 (en) * | 2021-06-11 | 2022-12-12 | Hybrit Development Ab | Process for the production of carburized sponge iron |
Also Published As
| Publication number | Publication date |
|---|---|
| KR20250161005A (en) | 2025-11-14 |
| WO2024196294A1 (en) | 2024-09-26 |
| SE546870C2 (en) | 2025-03-04 |
| CN120787265A (en) | 2025-10-14 |
| MX2025010814A (en) | 2025-10-01 |
| AU2024240537A1 (en) | 2025-09-18 |
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