JP2010024477A - Method for producing iron ore pellet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing pellet with which in a grate-kiln type pellet producing apparatus, the development of bursting in a preheating chamber of a grate-furnace can surely be prevented. <P>SOLUTION: In an upper space of the preheating chamber 5, the actual operational conditions (for example, at least one among the firing amount of a water-separating chamber burner 31, the firing amount of a preheating chamber burner 21, the grate-moving speed and the pellet layer thickness) are adjusted, so that the temperature difference ΔT=T<SB>2</SB>-T<SB>1</SB>between the atmospheric temperature T<SB>2</SB>measured with a preheating chamber inlet thermometer 43 separately arranged at the inlet part of the preheating chamber 5 excepting from a preheating chamber thermometer 44 for measuring the atmospheric temperature in the preheating chamber and the gas temperature T<SB>1</SB>measured with a fire-grate thermometer 42 at the outlet of the water-separating chamber arranged just below the grate 2 at the outlet part of the water-separating chamber 4 becomes smaller than the permissible temperature difference ΔT<SB>max</SB>preset based on the past operational result. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technology for producing iron ore pellets by a great kiln system for producing iron ore pellets used for blast furnace raw materials and the like.

  The manufacturing process for making iron ore pellets consists of drying, water separation, preheating, firing and cooling processes. Great kiln type iron ore pellet manufacturing equipment (hereinafter simply referred to as “Great kiln type firing equipment”). Conventionally, the one shown in the longitudinal sectional view of FIG. 1 is known. As shown in the figure, this great kiln type firing apparatus includes a great furnace 1, a rotary kiln (hereinafter also simply referred to as “kiln”) 9, and an annunculus 11.

  The great furnace 1 is composed of an endless traveling grate (hereinafter simply referred to as “grate”) 2 and raw pellets GP laid on the grate 2 in the order of a drying chamber 3, a water separation chamber 4, and a preheating chamber 5. While moving in the longitudinal direction of each chamber, the pellets (hereinafter referred to as “preheated pellets”) are dried, dewatered, and preheated by downward ventilation of the heating gas to give the pellets enough strength to withstand rolling in the kiln 9. It is.

  The raw pellet GP is granulated by blending limestone, dolomite, and the like as auxiliary raw materials with iron ore as a main raw material, and further adding moisture.

First, in the drying chamber 3, the raw pellet GP having a water content of about 8 to 9% by mass is dried at an ambient temperature of about 250 ° C. Next, in the water separation chamber 4, the dried raw pellets are heated to about 450 ° C., and mainly the crystal water in the iron ore is decomposed and removed. Furthermore, in the preheating chamber, the temperature of the pellet is raised to about 1100 ° C., the carbonate contained in limestone, dolomite, etc. is decomposed to remove CO ₂ and magnetite in the iron ore is oxidized. By producing preheated pellets having a strength that can sufficiently withstand rolling in the kiln 9 through such steps, it becomes possible to increase the productivity of the great kiln type baking apparatus.

  The rotary kiln 9 is directly connected to the great furnace 1 and is a cylindrical rotary furnace with a gradient. The rotary kiln 9 is charged from the preheating chamber 5 of the great furnace 1 by combustion by the kiln burner 10 disposed on the outlet side. While the dried, dewatered and preheated pellets are fired, the high-temperature combustion exhaust gas used for firing the pellets is fed into the preheating chamber 5 as a heating gas. Conventionally, fuel such as pulverized coal and coke oven gas is blown into the rotary kiln 9 by the kiln burner 10 and burned together with combustion air.

  In addition, a preheating chamber burner 21 is provided at the upper portion of the preheating chamber 5 as a kiln combustion exhaust gas temperature raising means for raising the temperature of the kiln combustion exhaust gas from the rotary kiln 9. Coke oven gas (hereinafter abbreviated as “COG”) or pulverized coal is used as fuel for the preheating chamber burner 21, and this COG or pulverized coal is burned with residual oxygen in the kiln combustion exhaust gas in the preheating chamber 5. Thus, the temperature of the kiln combustion exhaust gas is raised. By doing so, the strength of the preheated pellets can be increased, and the occurrence of kiln rings in the rotary kiln 9 (the pelletized material adhered to the brick surface of the kiln inner wall in the form of rocks) that can cause unstable operation is prevented. (See Patent Documents 1 and 2).

  Reference numeral 6 denotes a preheating chamber wind box group. The space below Great 2 is partitioned into a plurality of rooms along the pellet movement direction, and these rooms are called wind boxes. In other words, the preheating chamber windbox group 6 is composed of a plurality of windboxes, and nine windboxes, for example, are arranged in a row along the longitudinal direction (pellet movement direction) with respect to the preheating chamber 5. ing. Reference numeral 7 denotes a preheating chamber suction fan, which has a fan damper (not shown) for adjusting the suction air volume (downward flow volume), and is directed downward through the pellet layer on the great 2 and the wind box group 6 using the kiln exhaust gas as a heating gas. Are sucked out and sent to the next water separation chamber 4.

  Further, reference numeral 16 denotes a water separation chamber wind box group. For example, five air boxes are arranged in a line along the longitudinal direction (pellet movement direction) of the water separation chamber 4. Reference numeral 17 denotes a suction fan for the water separation chamber, which has a fan damper (not shown) for adjusting the suction air volume (downward ventilation volume), leads the preheating chamber exhaust gas A to the water separation chamber 4 as a heating gas, and this heating gas A Is sucked downward through the pellet layer on the great 2 and the wind box group 16 and sent out to the next drying chamber 3.

  The control technology of the preheating chamber atmosphere temperature by installing the preheating chamber burner 21 is very effective in increasing the strength of the preheating pellet when the pellet production rate is constant and the content of crystal water in the raw pellet GP is also constant. Means.

  By the way, in order to respond to the recent increase in steel demand, further increase in the production of pellets is required. In addition, with the recent deterioration of iron ore raw materials, an increase in the blending ratio of high crystal water ore to pellets is also required. However, if the pellet production rate is simply increased or the crystal water content in the raw pellet GP is increased while maintaining the pellet production rate to meet these requirements, the atmosphere in the water separation chamber 4 When the operation is performed while maintaining the temperature as usual, the pellet (particularly the lower layer pellet) is not sufficiently decomposed and removed in the water separation chamber 4, so that the crystal water remains inside the pellet. It is brought into the hotter preheating chamber 5. The pellets brought into the preheating chamber rapidly rise in temperature, the crystal water remaining inside the pellets is rapidly decomposed, the water vapor pressure inside the pellets rises rapidly, and bursting of the pellets occurs. The powder generated by bursting deteriorates the air permeability of the pellet layer, hinders uniform heating, increases the pressure loss of the pellet layer, destabilizes the operation, and decreases the strength of the preheated pellet. As a result, the powder generated in the preheating chamber 5 is brought into the kiln 9 and the preheated pellets having low strength are pulverized by rolling in the kiln 9, so that a kiln ring is formed and the operation cannot be continued. Therefore, in order to avoid the bursting in the preheating chamber 5, the pellet production rate has to be reduced eventually.

  Therefore, the applicant believes that the crystallization water can be sufficiently removed from the pellets in the water separation chamber 4 even at the time of increased production by raising the temperature of the exhaust gas from the preheating chamber 5, and the water separation chamber 4 also has a burner (hereinafter referred to as “burner”). (Referred to as “water separation chamber burner”) 31 (see Japanese Patent Application No. 2008-84178). However, the present situation is that the occurrence of bursting in the preheating chamber 5 has not been completely prevented even after the water separation chamber burner 31 is installed.

Here, the inventors indicate that the occurrence of bursting in the preheating chamber 5 is the pressure in the wind box closest to the kiln 9 at the pellet outlet of the preheating chamber 5 (hereinafter referred to as “preheating chamber wind box pressure”). .) It was found that it can be detected by fluctuations in _PPHWB . FIG. 2 is an example showing how the preheating chamber air box pressure P _PHWB changes over time under a constant operating condition. The preheating chamber air box pressure P _PHWB is normally −340 to −380 mmAq (gauge pressure, hereinafter The same, except that 1 mmAq = 9.80665 Pa.), But suddenly starts to decrease suddenly and becomes lower than −400 mmAq. As described above, the preheating chamber wind box pressure P _PHWB is greatly reduced than usual because _bursting occurs in the pellet layer of the preheating chamber 5, the air permeability of the pellet layer deteriorates, and the pressure loss rapidly increases. This is thought to be due to the increase.

Therefore, it was found that the occurrence of _{bursting in} the preheating chamber 4 can be detected by constantly monitoring the fluctuation of the preheating chamber wind box pressure _PPHWB , but since the detection is after the occurrence, the bursting is performed in advance. There has been a strong demand for the development of a means that can reliably prevent the occurrence of this.
JP-A-11-325740 JP 2005-60762 A

  Then, an object of this invention is to provide the pellet manufacturing method which can prevent generation | occurrence | production of bursting in the preheating chamber of a great furnace in a great kiln system pellet manufacturing apparatus.

  The inventors consider that the rate of temperature rise of the pellet when it is brought into the preheating chamber from the water separation chamber has the most influence on the occurrence of bursting in the preheating chamber. First, the effect is investigated in the following laboratory test. went.

  First, raw pellets having a particle size of 10 to 12 mm and a moisture content of about 8.5% by weight are obtained by a tire type pelletizer using a blended raw material used in a pellet manufacturing apparatus installed in the applicant's Kakogawa Works. Granulated. Then, with reference to the temperature pattern of the pellet lower layer obtained by thermocouple convection (see below) in the Great of the above pellet manufacturing apparatus, the raw pellets were dried at 105 ° C. for 20 minutes in a small dryer, and the moisture content Was dried pellets of about 0.2% by mass (corresponding to the drying chamber), and then the dried pellets were further heated at 300 ° C. for 5 minutes in a small dryer to obtain water separation pellets (corresponding to the water separation chamber). Then, this water separation pellet is placed in a small heating furnace adjusted to a predetermined atmospheric temperature and held for 2 minutes to form a preheating pellet (equivalent to a preheating chamber), and the temperature transition measured by a thermocouple set immediately above the pellet is linear. Approximately calculate the rate of temperature rise of the pellet, measure the mass ratio of the preheated pellet under 5 mm below the sieve, and use this as the powder ratio of the preheated pellet. did.

  In FIG. 3, the relationship between the temperature increase rate of a pellet and the powder rate of a preheating pellet is shown. As shown in the figure, when the heating rate of the pellet is below a certain value (6-7 ° C./s), the powder ratio of the preheated pellet is always kept below 0.5% by mass, whereas the heating rate of the pellet It has been found that when the value exceeds the above-mentioned fixed value, the powder ratio of the preheated pellets increases rapidly and bursting starts to occur.

  Therefore, from the result of the above laboratory test, it can be confirmed that the bursting rate in the preheating chamber can be prevented by controlling the temperature rising rate of the pellet when it is brought into the preheating chamber from the water separation chamber. It was.

  However, in the actual pellet manufacturing apparatus, it is not easy to directly measure the temperature rising rate of the pellet layer on the moving grate. For example, a metal mesh basket is filled with raw pellets, a long thermocouple inserted in the raw pellet packed layer is placed on the grate, and the temperature transition of the pellet layer as the grate moves is measured. Although it is performed in a spot manner (hereinafter referred to as “thermocouple flow”), it is not a means that can always be carried out because it is very costly and troublesome.

Therefore, we, instead of measuring the Atsushi Nobori rate of the pellets layer directly as a parameter corresponding to the Atsushi Nobori rate of the pellets layer can be measured at all times and the simple, syneresis chamber outlet Tu preheating chamber inlet temperature T ₂ It was thought that a temperature difference ΔT = T ₂ −T ₁ with respect to the lattice temperature T ₁ may be used.

First, we, the syneresis chamber outlet grate temperature T _1, and investigated the relationship between the temperature of the pellet lower portion which is measured with a thermocouple flow (Since the pellet layer is heated in a downward ventilation, pellets Since the lower layer is most likely to delay the temperature rise and bursting is likely to occur, the temperature of the pellet lower layer is usually measured by thermocouple flow.) As shown in FIG. 4, the thermocouple 42 as a water separation chamber outlet grate thermometer has a position in the height direction as close as possible to the lower layer part of the pellet at a position 200 mm directly below the Great 2 and a thermocouple for thermocouple flow. The pair was installed at a position of 35 mm directly above Great 2, which is the center position in the height direction of the pellet lower layer. And when the thermocouple flowing thermocouple reached the position just above the water grate outlet grate thermometer 42, the temperatures measured by both thermocouples (thermometers) were compared. as shown, syneresis chamber outlet grate temperatures T _1, although a slightly lower eye than the temperature of the pellet lower portion which is measured with a thermocouple flow, the temperature difference was always almost constant 25 ° C. and forth. Therefore, the water separation chamber outlet grate temperature T _1, it was confirmed that can evaluate the temperature of the pellet lower portion.

Therefore, in the pellet manufacturing apparatus installed in the applicant's Kakogawa Works, the relationship between the temperature difference ΔT between the preheating chamber inlet temperature T ₂ and the water separation chamber outlet grate temperature T ₁ and the preheating chamber wind box pressure P _PHWB. As a result, the relationship shown in FIG. 5 was obtained.

As shown in the figure, there is a strong correlation as a whole between the temperature difference ΔT and the preheating chamber wind box pressure P _PHWB (the straight line in the figure is a regression line), but the temperature difference ΔT is It can be seen that the number of cases (corresponding to occurrence of bursting) in which the preheating chamber wind box pressure P _PHWB greatly decreases from the regression line increases as it increases.

Therefore, maintaining the temperature difference ΔT below a predetermined temperature (for example, 850 ° C.) can sufficiently reduce the probability of a significant decrease in the preheating chamber air box pressure P _PHWB and prevent the occurrence of _bursting. It turns out that there is a possibility.

  Based on the above findings, the inventors have completed the following invention.

The invention according to claim 1 is the production of a great kiln type iron ore pellet in which the iron ore pellets are moved in a grate, heated sequentially in a drying chamber, a water separation chamber and a preheating chamber and then fired in a rotary kiln equipped with a kiln burner. In the method, separately from a thermometer (hereinafter referred to as “preheating chamber thermometer”), which is an upper space of the preheating chamber and measures the atmospheric temperature in the preheating chamber, it is separately provided at the pellet inlet of the preheating chamber. An ambient temperature (hereinafter referred to as “preheating chamber inlet temperature”) T ₂ measured by a measured thermometer (hereinafter referred to as “preheating chamber inlet thermometer”), and a pellet outlet portion of the water separation chamber, The temperature difference from the gas temperature (hereinafter referred to as “water separation chamber outlet grate temperature meter”) T ₁ measured with a thermometer (hereinafter referred to as “water separation chamber outlet grate thermometer”) provided immediately below the Great ΔT = T ₂ -T ₁ is to be less than the allowable temperature difference [Delta] T _max that has been determined in advance based on past operating experience, it is a manufacturing method of iron ore pellets, characterized by adjusting the current operating conditions.

  According to a second aspect of the present invention, the adjustment of the current operation condition is performed in the amount of combustion of a burner provided in the upper part of the water separation chamber (hereinafter referred to as “water separation chamber burner”), in the upper part of the preheating chamber. 2. The method for producing iron ore pellets according to claim 1, wherein at least one adjustment of a combustion amount of a burner (hereinafter referred to as “preheating chamber burner”), a great moving speed, and a pellet layer thickness is adjusted.

According to the present invention, the temperature difference ΔT = T ₂ −T ₁ between the preheating chamber inlet temperature T ₂ and the water separation chamber grate temperature T ₁ is an allowable temperature difference ΔT _max determined in advance based on past operation results. By adjusting the current operating conditions so as to be smaller, it is possible to reliably prevent the occurrence of bursting in the preheating chamber by suppressing the temperature rise rate of the pellets at the inlet of the preheating chamber. .

  As a result, by applying the present invention, it has become possible to reliably achieve increased pellet production or increased distribution of high crystal water ore.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG. 1 used for explanation in the above [Background Art].

Embodiment
As shown in FIG. 1, in order to raise the temperature of the preheating chamber exhaust gas A, the water separation chamber 4 is provided with a plurality of water separation chamber burners 31 for blowing COG, for example, into the water separation chamber 5 as gaseous fuel. The reason why the gaseous fuel is used as the fuel for the water separation chamber burner 31 instead of the pulverized coal is that the temperature of the preheating chamber exhaust gas A blown into the water separation chamber 4 is as low as about 400 to 450 ° C. Combustion does not continue without a source, whereas in the case of gaseous fuel, combustion continues automatically even without an ignition source. Further, as illustrated in FIG. 1, when the water separation chamber burner 31 is installed on the ceiling wall 4 a, if a pulverized coal burner is used, the burner frame becomes longer, so that the pellets on the outermost surface of the pellet layer are overheated, and the bursting From this point, it is preferable to use a gaseous fuel with a short burner frame.

In the following description, “inlet” and “exit” of “water separation chamber inlet” and “water separation chamber outlet” are based on the moving direction of the pellets. It is recommended that the plurality of burners 31 be disposed between (1/3) L _{DH to} 0.98L _DH (L _DH : total length of the water separation chamber) with the water separation chamber inlet 4b as a base point. If the burner 31 is installed at a position _lower than (1/3) LDH from the water separation chamber inlet 4b as a base point, the ambient temperature in the vicinity of the water separation chamber inlet 4b rises, and the adhering water is not sufficiently dried in the drying chamber 3. This is because bursting is likely to occur when the pellets are brought into the water separation chamber 4 while remaining. On the other hand, when the burner 21 is installed at a position exceeding 0.98L _DH from the water separation chamber inlet 4b (that is, a position less than 0.02L _DH from the water separation chamber outlet 4c), the burner 21 is provided on the partition wall of the water separation chamber outlet 4c. This is because the refractory of the partition wall is easily damaged by the radiant heat from the burner frame. The plurality of burners 31 are more preferably disposed between (1/2) L _{DH and} 0.95L _{DH with} the water separation chamber inlet 4b as a base point, and (1/3) L _{DH to} 0.92L _DH. It is particularly preferable to arrange them between the two.

Then, a thermoelectric as a water discharge chamber outlet grate thermometer is located at the pellet outlet portion of the water separation chamber 4 (for example, the central position in the great movement direction of the wind box closest to the kiln 9 of the water separation chamber 4) and directly below the great 2. A pair 42 is installed. Separately from the preheating chamber thermometer 44, the pellet inlet portion of the preheating chamber 5 (for example, the central position in the great moving direction of the wind box on the most inlet side of the preheating chamber 5), and in the upper space of the pellet layer, A thermocouple 43 is installed as a room inlet thermometer. Here, as described above, the thermocouple 42 is installed at the pellet outlet of the water separation chamber 4 and immediately below the Great 2 as described above. This is because the temperature corresponding closely is measured as accurately as possible. The reason why the thermocouple 43 is installed at the entrance of the preheating chamber 5 and in the upper space of the pellet layer is that the temperature of the atmospheric gas that heats the pellet layer immediately after being brought into the preheating chamber 5 is set. This is for measuring as accurately as possible. Here, in order to sufficiently ensure the temperature measurement accuracy, the "pellet outlet of water separation chamber 4", 0.2 L _DH (more preferably 0.1 L _DH) from syneresis chamber 4 outlet 4c means a range of the "pellet inlet of the preheating chamber 5", 0.2 L _PH from the preheating chamber 5 the inlet (more preferably 0.1 L _{PH; however, L PH:} preheating chamber full length) shall mean the range.

Then, at these thermocouples 42 and 43, constantly measures the water separation chamber outlet grate temperature T ₁ and the preheating chamber inlet temperature T _2.

On the other hand, as already described in the above [Means for Solving the Problems], the preheating chamber 41 is provided with a pressure gauge (preheating chamber wind box pressure gauge) 41 installed in the wind box closest to the kiln 9 in the preheating chamber 5. The wind box pressure _PPHWB is constantly measured. Note that the pressure in the wind box closest to the kiln 9 in the preheating chamber 5 is measured so that the pressure change caused by the bursting can be detected at any position in the preheating chamber 5. Because.

Then, the relationship between the temperature difference ΔT and the preheating chamber wind box pressure P _PHWB collected in advance in the operation carried out in the past is plotted in, for example, a scatter diagram as shown in FIG. ΔT _max is determined in advance. For example, in the case of the relationship shown in FIG. 5, as described above, the allowable temperature difference ΔT _max may be set to 850 ° C., which has a relatively small number of plots greatly deviating from the regression line.

Then, the temperature difference ΔT (= T ₂ −T ₁ ) is calculated from T ₁ and T ₂ measured in the current operation, and this temperature difference ΔT is calculated from the allowable temperature difference ΔT _max determined in advance as described above. What is necessary is just to adjust the present operating conditions so that it may become small.

  As specific means for adjusting the current operating conditions, means for adjusting the combustion amount of the water separation chamber burner 31, the combustion amount of the preheating chamber burner 21, the great moving speed, the pellet layer thickness, etc. may be used. These means may be used alone, or a plurality of means may be used in combination.

As described above, by adjusting the current operating conditions so that the temperature difference ΔT is smaller than the allowable temperature difference ΔT _max , the probability of a significant decrease in the preheating chamber wind box pressure P _PHWB is reduced. The occurrence of bursting within 5 can be more reliably prevented.

  As a result, good air permeability of the pellet layer is maintained, uniform heating is ensured, and the strength of the preheated pellet is increased. This high-strength preheated pellet is less likely to be pulverized even if it is rolled in the kiln 9, and the kiln ring is prevented from being produced, so that more stable, high-productivity and high-quality pellets can be produced. realizable.

It is a longitudinal cross-sectional view which shows an example of the great kiln system iron ore pellet manufacturing apparatus which concerns on implementation of this invention. It is a graph which shows the mode of a time-dependent fluctuation | variation of the preheating chamber wind box pressure. It is a graph which shows the relationship between the temperature increase rate of a pellet, and the powder rate of a preheating pellet. It is a longitudinal cross-sectional view which shows the positional relationship in the height direction of the thermocouple for thermocouple flow, and the water grate exit grate thermometer. And the temperature difference ΔT between the preheating chamber inlet temperature T ₂ and syneresis chamber outlet grate temperature T _1, is a graph showing the relationship between the preheating chamber wind box pressure P _PHWB.

Explanation of symbols

1 ... Great furnace 2 ... Traveling Great (Great)
DESCRIPTION OF SYMBOLS 3 ... Drying room 4 ... Water separation room 4a ... Water separation room ceiling wall 4b ... Water separation room inlet 4c ... Water separation room outlet 5 ... Preheating room 6 ... Preheating room wind box group 7 ... Preheating room suction fan 9 ... Rotary kiln 10 ... Kiln burner DESCRIPTION OF SYMBOLS 11 ... Annulakura 16 ... Water box group 17 for water separation chambers Suction fan 21 for water separation chambers ... Preheating chamber burner 31 ... Water separation chamber burner 41 ... Preheating chamber wind box pressure gauge 42 ... Water separation chamber outlet grate thermometer 43 ... Preheating chamber inlet Thermometer 44 ... Preheating chamber thermometer A ... Preheating chamber exhaust gas (heating gas)
GP ... Raw pellet

Claims (2)

In a method for producing iron ore pellets of a great kiln method in which iron ore pellets are moved in a great manner, sequentially heated in a drying chamber, a water separation chamber and a preheating chamber and then fired in a rotary kiln equipped with a kiln burner.
Separately from a thermometer that measures the ambient temperature in the preheating chamber (hereinafter referred to as “preheating chamber thermometer”), which is an upper space of the preheating chamber, a temperature provided separately at the pellet inlet of the preheating chamber The atmospheric temperature (hereinafter referred to as “preheating chamber inlet temperature”) T ₂ measured by a meter (hereinafter referred to as “preheating chamber inlet thermometer”), and the pellet outlet portion of the water separation chamber immediately below the great A temperature difference ΔT = T with a gas temperature (hereinafter referred to as “water separation chamber outlet grate temperature meter”) T ₁ measured by a thermometer (hereinafter referred to as “water separation chamber outlet grate thermometer”) ₂ -T ₁ is to be less than the allowable temperature difference [Delta] T _max that has been determined in advance based on past operating experience, the production method of iron ore pellets, characterized by adjusting the current operating conditions.   The adjustment of the current operating conditions is performed by adjusting the amount of combustion of a burner provided in the upper part of the water separation chamber (hereinafter referred to as “water separation chamber burner”), the burner provided in the upper part of the preheating chamber (hereinafter referred to as “preheating chamber”). The method for producing iron ore pellets according to claim 1, wherein at least one adjustment of a combustion amount, a great moving speed, and a pellet layer thickness of “burner”) is performed.

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