JP5411615B2 - Manufacturing method of carbonized material agglomerates - Google Patents

Description

  The present invention relates to a method for producing an agglomerated carbonaceous material agglomerated by hot forming, which can be used as a raw material for vertical furnaces such as blast furnaces and cupolas, and further improves the strength of the agglomerated carbonaceous material agglomerated material. It relates to an improved technology.

  The applicant of the present invention is a conventional carbonaceous material-internal cold by hot-forming a mixture of fine ore and softening-melting carbonaceous material for the purpose of using as raw materials for vertical furnaces such as blast furnaces and cupolas. We have developed an agglomerate of carbonaceous material that can provide high strength without adding a binder such as cement, such as pellets.

  Such a carbonaceous material-incorporated agglomerated material (hereinafter also simply referred to as “agglomerated material”) can be produced, for example, by a process as shown in FIG. That is, the powdered iron ore B is heated to 400 to 800 ° C. by a rotary kiln (raw material heating means) 12 and softened and melted powdered coal A is separately softened and melted by a rotary dryer (carbon material heating means) 11. After drying at a temperature of less than 250 ° C. that does not occur, these heated pulverized coal A (hereinafter also simply referred to as “coal”) and pulverized iron ore B (hereinafter also simply referred to as “iron ore”). ) Is mixed with the mixer 13 to obtain a heated mixture C ′ at 250 to 550 ° C., which is a temperature at which the powdered coal A is softened and melted. Then, this heated mixture C ′ is hot-formed by a twin roll type molding machine (molding means) 4 to be briquetted, and if necessary, agglomerated by removing residual tar in a degassing tank (heat treatment means) 5. E is obtained (see Patent Documents 1 and 2).

  Here, the manufacturing method described in Patent Documents 1 and 2 is a method in which high-temperature powdered iron ore B and low-temperature powdered coal A are mixed and heated to a temperature at which powdered coal A is softened and melted. However, it is not easy to mix the powdered iron ore B and the powdered coal A uniformly in a short time with the industrial-scale mixer 13. For this reason, mixing is likely to be uneven, and when the amount of the powdered coal A is too small relative to the amount of the powdered iron ore B, the temperature of the powdered coal A is excessively increased and does not remain in the softened and melted state. On the other hand, when the amount of powdered coal A is excessive with respect to the amount of powdered iron ore B, the temperature of the powdered coal B does not reach the softening start temperature. As a result, the effect of the binder is reduced as a whole. As a result, there was a problem that the strength of the carbonized material agglomerated product E obtained in the laboratory scale manufacturing apparatus could not be sufficiently obtained when it became an industrial scale manufacturing apparatus.

  In an attempt to improve the strength of the carbonaceous agglomerate E in an industrial scale manufacturing apparatus, for example, when the heating temperature of the powdered iron ore B is increased to raise the temperature of the heated mixture C ′, Where the amount of pulverized coal A is excessive with respect to the amount, the temperature of the pulverized coal B reaches the softening start temperature and the effect as a binder is exhibited. On the other hand, when the amount of pulverized coal A is too small, the temperature of the pulverized coal A increases too much, and the ratio of not reaching the softened and molten state but further reaching the coke state increases. The effect of improving the strength of the carbonized material agglomerated material E corresponding to the increase in energy consumption for increasing the heating temperature of the steel cannot be sufficiently obtained.

  In addition, when trying to improve the strength of the carbonaceous material agglomerate E in an industrial scale manufacturing apparatus, for example, when the blending ratio of the powdered coal A to the powdered iron ore B is increased, the softening and melting amount of the coal increases and the coal Although the cold strength of the material-incorporated agglomerated material E is improved, the carbon content in the carbonized material-incorporated agglomerated material E increases too much, so when it is inserted into a vertical furnace, There arises a problem that the strength decreases.

  For this reason, establishment of the manufacturing technique of the carbonaceous material internal agglomerated material E which can ensure the intensity | strength of the carbonaceous material internal material agglomerated material E was requested | required also in the manufacturing apparatus of the industrial scale.

  Here, in Patent Document 3, powdered iron ore and flux are kneaded to form pseudo particles (corresponding to pellets), and the pseudo particles (pellets) and coal are mixed to form a raw material mixed powder. A method is disclosed in which a powder is heated above the softening temperature of coal to soften or melt the coal, and then the raw material mixed powder is agglomerated to produce an agglomerated carbonaceous material.

  However, the technique described in Patent Document 3 is intended to promote melting and dropping of the carbonaceous material agglomerated material in the vertical furnace, and coal is not contained in the pellets (pseudo particles). The material is packaged in a pellet (pseudoparticle), heated and hot-formed. For this reason, it is assumed that the softened melt of coal does not sufficiently penetrate to the center of the pellet (pseudoparticle), and there is a high possibility that the strength of the carbonaceous material agglomerated material cannot be sufficiently obtained.

  On the other hand, since the present invention contains the powdered carbonaceous material in the pellet from the beginning (internally) and heat-forms it by heating, the powdered iron-containing raw material and the powdered carbonaceous material are uniformly contacted in advance. The powdered carbon material is softened and melted from the state, and the strength of the carbonaceous material agglomerated material is reliably improved.

Japanese Patent No. 3502011 JP 2001-294944 A JP-A-2005-325412

  Therefore, the present invention provides a method for producing an agglomerated carbonaceous material agglomerated material that can ensure the strength of the agglomerated carbonaceous material agglomerated material without increasing energy consumption even in an industrial scale production apparatus. Objective.

  The invention according to claim 1 is a granulating step of granulating a mixed raw material comprising a powdered carbonaceous material having softening and melting properties and a powdered iron-containing raw material into a pellet, A pellet heating step of heating to a maximum fluidity temperature + 50 ° C. or less above the softening start temperature of the carbonaceous material, and a hot molding step of hot-molding the heated pellet to form a carbonized material agglomerated product. This is a method for producing an agglomerated carbonaceous material.

  Invention of Claim 2 is a manufacturing method of the carbon material interior agglomerated product of Claim 1 in which the said mixed raw material contains a powdery flux further.

  Invention of Claim 3 is a manufacturing method of the carbon material interior agglomerate of Claim 1 or 2 which makes the average particle diameter of the said pellet 1-15 mm.

  According to a fourth aspect of the present invention, the molding machine used in the hot molding step is a twin-roll molding machine, the average particle size of the pellets is larger than the roll gap of the twin-roll molding machine, and the twin roll It is a manufacturing method of the carbon material interior agglomerated material of Claim 3 made smaller than the pocket depth of a molding machine.

According to a fifth aspect of the present invention, in the pellet heating step, at least one of ungranulated powdered carbonaceous material, powdered iron-containing raw material and powdered flux is added to the pellet and heated together. a method for producing a carbonaceous material furnished agglomerate according to any one of that請 Motomeko 1-4.

The invention according to claim 6, between the front Symbol pellet heating step and the hot-forming process, of claims 1-5 in which a pellet crushing step of crushing a portion of said heated pellets It is a manufacturing method of the carbonaceous material agglomerate of any one of Claims 1.

  Invention of Claim 7 is a manufacturing method of the carbonaceous material agglomerate of any one of Claims 1-6 heated in the atmosphere of oxygen-containing gas in the said pellet heating process.

  According to the present invention, after pelletizing a mixed raw material composed of a powdered carbon material having softening and melting properties and a powdered iron-containing raw material, the mixture is heated to a temperature at which the powdered carbon material is softened or melted, and then heated. By compacting, the powdered carbonaceous material and the powdered iron-containing raw material are softened or melted in a state in which the powdered carbonaceous material and the powdered iron-containing raw material are in contact with each other in advance. Even in this manufacturing apparatus, the strength of the carbonized material agglomerated material is reliably improved without increasing the energy consumption.

It is a flowchart which shows schematic structure of the manufacturing apparatus of the carbonaceous material interior agglomerate based on one Embodiment of this invention. It is a flowchart which shows schematic structure of the manufacturing apparatus of the carbonaceous material agglomerated material in a prior art.

(Embodiment)
FIG. 1 shows a schematic configuration of an apparatus for producing an agglomerated carbonaceous material according to an embodiment of the present invention. In addition, the same code | symbol was used for the apparatus and substance which are common in FIG. 2 demonstrated by the said prior art. Hereinafter, powder iron ore will be described as a representative example as a powder iron-containing raw material. Iron ore and carbonaceous material (eg, coke powder, general coal, anthracite, oil coke, etc.) that has substantially no softening and melting property are pulverized when necessary to obtain particles of 74 μm or less. 70% powder. Among the carbon materials, the carbon materials having softening and melting properties (for example, caking coal, non-slightly caking coal, SRC, etc.) need not be made as fine as the carbon materials having substantially no softening and melting properties. In order to facilitate the pelletization, the powdered iron ore and the carbonaceous material having substantially no softening and melting properties are uniformly mixed, and pulverized to about 1 μm or less, preferably 500 μm or less, more preferably about 100 μm or less. desirable.

[Granulation process]
The powdery carbonaceous material A and the powdered iron ore B adjusted in particle size in this way are mixed to form a mixed raw material, and this mixed raw material is granulated into pellets C by adding an appropriate amount of water with a granulator.

  The average particle size of the pellet C is preferably 1 to 15 mm, more preferably 1.5 to 10 mm, and particularly preferably 2 to 5 mm. Here, the average particle size of the pellets C is obtained by sieving the pellets C having a particle size distribution for each particle size range, and weighting the representative diameter of each particle size range by the mass ratio of the pellets C existing in each particle size range. It is a value obtained by averaging.

  If the particle size of the pellet C is too small, the mass ratio of the powdered carbon material A and the powdered iron ore B in each pellet C tends to be non-uniform, while if the particle size of the pellet C is too large, In addition to the time required to heat to the center, depending on the size of the agglomerate D, the total mass of pellets C entering the pocket of the molding machine tends to vary during molding, This is because bursting (explosion) is likely to occur during heating, and in any case, there is a high possibility of causing a decrease in strength of the carbonaceous material agglomerated material D.

  When the molding machine used in the hot forming step described later is a twin roll molding machine, the average particle size of the pellets satisfies the above-mentioned rule, and further exceeds the roll gap of the twin roll molding machine. And it is preferable to make it below the pocket depth of this twin roll type molding machine.

  By setting the average particle size of the pellets to be equal to or larger than the roll gap, the biting property to the molding machine is improved, the molding pressure can be increased, and the agglomerated material D is set to be equal to or less than the pocket depth. The apparent density of the agglomerated material D can be increased and the strength of the agglomerated material D can be improved.

  As the granulator 1, a known disk-type pelletizer or drum-type pelletizer can be used.

[Pellet heating process]
The granulated pellet C is obtained by a pellet heating device (for example, an externally heated rotary kiln) 2 at 300 ° C. or higher and the highest Geecerer fluidity temperature + 50 ° C. or lower, preferably higher than the softening start temperature of the powdered carbonaceous material. It is heated to a temperature of + 50 ° C. or lower, more preferably a softening start temperature + 20 ° C. or higher and a maximum fluidity temperature + 30 ° C. or lower. Here, the softening start temperature and the maximum fluidity temperature vary depending on the brand of the coal. Generally, the softening start temperature is about 350 to 400 ° C, and the maximum fluidity temperature is about 450 ° C.

  If the heating temperature is too low, softening of the powdered carbonaceous material A will not occur. On the other hand, if the heating temperature is too high, the powdered carbonaceous material A will not stay in the softened and melted state and will further progress to coking. In this case, the effect as a binder is reduced.

  The reason why the external heating type is employed as the pellet heating device 2 is that when heated by the internal heating type heating device, the pellet C is rapidly heated and bursting (explosion) is likely to occur.

Moreover, it is also preferable that air is blown into the pellet heating device 2 as an oxygen-containing gas, for example, and the pellet C is heated in an atmosphere of the oxygen-containing gas. The volatile matter generated from the powdered carbonaceous material A in the pellet C by heating is converted to methane (CH ₄ ), which is the main gas component of the volatile matter, by the catalytic action of the powdered iron ore B also present in the pellet C. This is because the combustion reaction proceeds at a temperature of 300 ° C. or higher which is lower than 540 ° C. and 570 ° C., which are the ignition temperatures of hydrogen (H ₂ ), and promotes the temperature rise of the pellet C (see Japanese Patent Application No. 2008-285280).

  In addition, although the heating temperature of the pellet C can be adjusted by increasing / decreasing the blowing amount of the oxygen-containing gas G, the blowing amount of the oxygen-containing gas G is generated from the powdered carbon material A if it is excessively increased. In addition to complete combustion of the volatile matter, the excess oxygen gas component remains in the atmospheric gas after combustion, so that the fixed carbon content in the powdered carbon material A is oxidized and consumed. Therefore, the amount of oxygen in the oxygen-containing gas G supplied to the heating device 3 is made smaller than the chemical equivalent required for complete combustion of the volatile matter generated from the powdered carbon material A.

  The exhaust gas H discharged from the pellet heating device 2 may contain a tar content generated from the powdered carbon material A, which may condense and adhere in the exhaust gas system and block the piping and the like. To prevent this, although not shown, for example, a method in which a combustor is installed in the exhaust gas discharge duct of the pellet heating device 2 to burn and decompose tar components to gasify, or a burner is installed in the exhaust duct. A method may be employed in which the volatile component (hydrocarbon gas) in the exhaust gas is partially combusted and maintained at a temperature at which the tar component is not condensed and conveyed to the exhaust gas treatment device.

[Hot forming process]
The heated pellet C is made into one briquette (agglomerated product) D with a plurality of pellets C using a hot molding machine (for example, a twin roll type molding machine for hot molding) 4. Press molding. Since the individual pellets C contain the softened or melted carbon material uniformly in the inside thereof, the plurality of pellets C are crushed when pressed by the molding machine 4, and the internal pellets are not softened. The molten carbon material is extruded and integrated on the surface, and a high-strength briquette (agglomerated product) E is obtained after cooling.

[Heat treatment process]
The agglomerate D is charged into a heat treatment apparatus (for example, a shaft furnace) 5 adjusted to a temperature equal to or higher than the hot forming temperature, and the volatile matter and tar content remaining in the agglomerate D are removed. Solidify. As a result, when the agglomerate D is charged in the vertical furnace and heated, the carbonaceous material is no longer softened, the strength of the agglomerate E is maintained, and a large amount of tar is generated. And troubles such as tar sticking to the exhaust gas system of the vertical furnace can be prevented.

  The agglomerate H heat-treated in the shaft furnace 5 may be ignited or burnt if discharged into the atmosphere while being hot. Therefore, the agglomerate H may be cooled to 400 ° C. or lower with an inert gas such as nitrogen gas at the bottom of the shaft furnace 5. It is desirable to discharge from.

  The agglomerated material D after degassing is sieved with a screen 6, and the under-sieving powder F is returned to the rotary kiln 2, the mixer 3 or the like and reused, while the mass E on the sieve has a desired high strength. Collected as an agglomerated carbonaceous material agglomerate.

(Modification)
In the said embodiment, although the example which uses only a powdered iron ore and a powdered carbon material as a mixed raw material was shown in the granulation process, you may contain powdery flux (limestone, dolomite, etc.) further.

  In the above embodiment, an example of heating only the granulated pellets in the pellet heating step has been described. However, the powdered carbonaceous material (having a softening and melting property, having an ungranulated pellet, And at least one of powdered iron-containing raw material and powdered flux may be added to the pellet and heated. Softened or melted carbon material present in the pellet C by pressurization during hot forming even if the raw material in powder form (even if there is no powdered carbon material having softening and melting properties) is mixed in the pellet Is extruded to the outside, so that the powdery raw material is also bonded to obtain a high-strength agglomerated material D. Rather, in the case of only the pellet C, there is a gap between the pellet C and the pellet C, so that voids are likely to remain in the agglomerated material D after pressure molding, whereas the pellet C remains in a powdery state. When the raw material is added, the gap is not reduced or eliminated, so that an effect of making it difficult to form voids in the agglomerated material is obtained. However, if the amount of raw material added in powder form is excessively increased, the effect of uniform dispersion of the powdered carbonaceous material in the powdered iron ore is reduced, and the effect of improving the strength of the agglomerated material is diminished. Therefore, it is preferable that the added mass of the raw material in the form of powder is 5 to 50%, more preferably 10 to 30% of the mass of the pellet C.

Alternatively, instead of or in addition to adding the ungranulated powder to the pellet and heating, it was heated at the latter stage of the pellet heating step or between the pellet heating step and the hot forming step You may provide the pellet crushing process which crushes a part of pellet. Thereby, after improving mixing nature as much as possible, since the part can be returned to powder form after heating in the pelletized state, the intensity | strength of an agglomerate further improves. As the crushing means, a conventional crusher, a high speed mixer or the like can be used.

  In the above embodiment, air is exemplified as the oxygen-containing gas G. However, oxygen gas or oxygen-enriched air may be used instead of air. Thereby, since the atmospheric gas temperature after combustion rises even with the same oxygen amount as air, the amount of oxygen-containing gas G added to the mixer 3 can be reduced, and the amount of exhaust gas from the mixer 3 is also reduced. The cost of the exhaust gas treatment facility is reduced. Further, since the exhaust gas from the mixer 3 contains pyrolysis gas (volatile matter) mainly composed of hydrocarbons, oxygen gas or oxygen-enriched air is used when using this as fuel. However, since the reduction of exhaust gas calories due to the addition of the oxygen-containing gas G is suppressed rather than simply using air, the value as a fuel is increased.

  Moreover, although the example which provided the heat processing process was shown in the said embodiment, when the usage-amount of the carbonaceous material agglomerated material in a vertical furnace is small, since the total amount of tar generation in a vertical furnace also decreases. The heat treatment step may be omitted. In addition, the carbonaceous material agglomerate produced by the method of the present invention is gradually heated in the furnace when charged into the vertical furnace, so even if volatile matter remains inside, Volatiles are gradually removed, so there is no risk of the agglomerates exploding. When the heat treatment step is omitted, the treatment may be performed in an oxygen-containing gas atmosphere in all steps of the carbonaceous material supply step, the mixing step, and the hot forming step, or the oxygen-containing gas in any one or two steps. You may process in atmosphere.

  Moreover, in the said embodiment, although the example using a twin roll type molding machine was shown as a hot molding machine, you may use an extrusion molding machine.

  In order to confirm the effect of the present invention, the following tests were conducted.

  Powdered iron ore (brand: MBR, particle size: -1 mm) is used as the powdered iron-containing raw material, and powdered coal (brand: SONOMA, volatile content: 28.8% by mass, highest) Fluidity [log (DDPM)]: 3.94, softening start temperature: 390 ° C., maximum fluidity temperature: 442 ° C., particle size: −75 μm, 90% by mass) were used. And the briquette was made into the mixture ratio of powdered iron ore: powdered carbonaceous material = 75: 25-85: 15 (mass ratio), and the manufacturing speed of briquette was 1.2 t / h.

[Comparative example]
The briquette manufacturing test by the conventional manufacturing method (refer FIG. 2 ) which does not pelletize was implemented. As the carbonaceous material supply means (with heating function) and the raw material heating means, a screw transfer type heater that performs external heating using COG as a fuel was used. Further, as a mixing means, a horizontal paddle type mixer (container inner diameter 0.44 m, container effective length 4.5 m, with air blowing port) was used for mixing while blowing air. The mixer employs a system in which COG is used as fuel and heat is maintained by external heating. Moreover, as a hot forming means, a twin roll type molding machine (roll diameter: 800 mm, roll gap: 2 mm, pocket depth: 8 mm) was used, with a forming pressure: 800 kN, length: 30 mm × width: 25. It was molded into an egg-shaped briquette of 7 mm × thickness: 20 mm. As the heat treatment means, a screw transfer type heater that performs external heating using COG as a fuel is used as in the carbonaceous material supply means (with a heating function) and the raw material heating means, and the processing temperature is 650 ° C. and the residence time is 6. Degassing treatment was performed for 4 minutes.

  Powdered coal is preheated to 200-300 ° C with carbonaceous material supply means (with heating function), while powdered iron ore is heated to 450-600 ° C with raw material heating means, mixed with a mixer, and then molded. It was molded into briquettes with a machine and degassed with heat treatment means. As a result, the crushing strength of the obtained briquette was 1180 to 1470 N / piece (120 to 150 kgf / piece).

[Invention Example]
The briquette manufacturing test by the manufacturing method (refer FIG. 1) based on this invention which pelletizes was implemented. In addition, the example of this invention added the pellet manufacturing apparatus to the manufacturing apparatus used by the said comparative example, and implemented it as follows.

  Of the total amount of powdered coal and powdered iron ore to be used, 44% by weight of powdered coal and 78% by weight of powdered iron ore are mixed, and lignin and water as a binder are added in an appropriate amount. A raw pellet having a particle diameter of 1 to 5 mm (mass ratio of powdered coal to powdered iron ore in the raw pellet = 80: 20) was produced at a rotation speed of 9.5 rpm. The raw pellets were dried with a dryer so that the water content was 1% by mass or less to obtain dried pellets.

  And while the remaining powdered carbonaceous material is preheated to 200-300 ° C. by the carbonaceous material supply means (with heating function), the dried pellet is heated to about 400 ° C. by the raw material heating means together with the remaining powdered iron ore, These were charged together in the external heating type mixer and further heated at 300 to 400 ° C. The heated pellets and powdery raw material were formed into briquettes with a molding machine, and degassed with heat treatment means. As a result, the crushing strength of the obtained briquette was 1670-1960 N / piece (170-200 kg / piece).

1: Granulator 2: Pellet heating device (external heating rotary kiln)
4: Hot forming machine (double roll type forming machine)
5: Heat treatment equipment (shaft furnace)
6: Screen A: Powdered carbon material (powdered coal)
B: Powdered iron-containing raw material (powdered iron ore)
C: Pellet D: Carbonaceous material agglomerate (briquette)
E: Carbonized material agglomerated material (sieve lump)
F: Sieve powder G: Oxygen-containing gas (air)
H: exhaust gas

Claims (7)

A granulating step of granulating a mixed raw material consisting of a powdered carbon material having softening and melting properties and a powdered iron-containing raw material into pellets;
A pellet heating step of heating the pellet to a maximum fluidity temperature of + 50 ° C. at 300 ° C. or higher;
A hot forming step of hot forming the heated pellets into a carbonaceous material agglomerate;
A method for producing an agglomerated carbonaceous material, comprising:   The method for producing an agglomerated carbonaceous material agglomerated product according to claim 1, wherein the mixed raw material further contains a powdery flux.   The method for producing an agglomerated carbonaceous material agglomerated product according to claim 1 or 2, wherein the pellets have an average particle size of 1 to 15 mm.   The molding machine used in the hot molding process is a twin-roll molding machine, and the average particle size of the pellets is larger than the roll gap of the twin-roll molding machine and smaller than the pocket depth of the twin-roll molding machine. The manufacturing method of the carbonaceous material interior agglomerated material of Claim 3. In the pellet heating step, any non-granulation, powdered carbonaceous material, at least one powdered iron-containing raw material and powdery flux, the 請 Motomeko 1-4 it heated together was added to the pellet A method for producing an agglomerated carbonaceous material agglomerated product according to claim 1. Between the front Symbol pellet heating step and the hot-forming process, the carbonaceous material according to claim 1 in which a pellet crushing step of crushing a portion of said heated pellets A method for producing an interior agglomerate.   In the said pellet heating process, the manufacturing method of the carbon material interior agglomerated material of any one of Claims 1-6 heated in the atmosphere of oxygen-containing gas.

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