JP5421685B2 - Production method of coal-type agglomerated ore for vertical furnace - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a method for producing a vertical furnace carbonaceous material-containing agglomerated mineral having excellent handling strength that can be used as a raw material for vertical furnaces such as blast furnaces and cupolas.

  For the purpose of using as a raw material for vertical furnaces such as blast furnaces and cupolas, the present inventors have formed a conventional carbon material interior by hot forming a mixture of fine ore and a soft and meltable carbon material. A carbonaceous material agglomerated ore has been developed that can obtain high strength without adding a binder such as cement such as cold pellets (see, for example, Patent Documents 1 to 3).

  This carbon material agglomerated ore contains tar content derived from the interior carbon material. The behavior of tar when this carbonaceous material-containing agglomerated mineral is used as a part of the charge in a blast furnace, which is an example of a vertical furnace, will be described with reference to FIG. As the carbon material agglomerated ore charged from the top of the furnace descends in the furnace, its temperature rises, and when the temperature rises above the thermal history at the time of molding, the pyrolysis reaction of the interior carbon material begins. It restarts, and the vaporized tar as its product is released from the carbonaceous agglomerate. This tar is discharged out of the furnace together with the top gas as tar vapor. In general, since a blast furnace has a wet dust collection facility, tar steam is condensed and collected in the dust-collected water of the wet dust collection facility. Therefore, this condensed tar needs to be recovered by a water treatment device, but in a blast furnace that does not assume the generation of tar in the furnace, the water treatment device does not have a tar recovery function from treated water. It is necessary to remove the tar.

  Therefore, the present applicant, as a result of various studies on the residual tar content in the carbonaceous material agglomerated ore, as a result of hot mixing a mixture of the powdered iron-containing raw material and the powdered carbonaceous material having a soft melting property at 250 to 550 ° C. A molded product produced by molding is further subjected to heat treatment in an inert gas (non-oxidizing gas) atmosphere by adjusting the treatment temperature and / or treatment time in the range of 500 to 800 ° C. and 5 to 60 minutes. , Found that the tar content in the carbon material is almost eliminated, and that the carbon material agglomerate with higher strength and less tar content, which is more suitable for the raw materials of vertical furnaces such as blast furnaces, can be obtained. A patent application has already been filed (see Patent Document 4).

  However, from the viewpoint of securing the strength of the carbonaceous material agglomerated mineral obtained by removing tar by the heat treatment, the treatment temperature and treatment time are limited as described above, and there is a limit to improving the efficiency of the heat treatment. As a result, the heat treatment equipment could not be made compact enough.

JP 2006-241577 A JP 2007-2111271 A JP 2008-95124 A JP 2007-2111296 A

  Therefore, the present invention provides a method for producing a vertical furnace carbonaceous material agglomerated ore that can further improve the efficiency of heat treatment while ensuring the strength of the carbonaceous material agglomerated mineral obtained by removing tar by heat treatment. The purpose is to provide.

The invention according to claim 1 is a volume of 6-12 cm ³ produced by hot forming a mixture of powdered iron-containing raw material and powdered carbon material having soft melting property at a hot forming temperature: 250-500 ° C. Furthermore , after adding 10-20 mass% exterior carbonaceous material with respect to the said molded object, atmospheric temperature T (unit: degreeC) is over 800 degreeC over 1300 degreeC in oxidizing gas atmosphere. In the following, a carbonaceous material agglomerated ore is obtained by performing a heat treatment under the condition of a treatment time t (unit: min) of 1200 / T to 2400 / T to remove a tar content in the molded product. It is a manufacturing method of the carbon material interior agglomerate for vertical furnaces.

Invention of Claim 2 is a manufacturing method of the carbonaceous material interior agglomerated for vertical furnace of Claim 2 which performs the said heat processing in non-oxidizing gas atmosphere.

Invention of Claim 3 is a manufacturing method of the carbon material interior agglomerated for vertical furnace of Claim 2 which performs the said heat processing in non-oxidizing gas atmosphere .

According to a fourth aspect of the present invention, when the heat treatment is performed in an oxidizing gas atmosphere, 10-20% by mass of an exterior carbonaceous material is added to the molded product. It is a manufacturing method of a material interior agglomerated mineral.

The invention according to claim 5 is the invention according to any one of claims 2 to 4, wherein an average temperature rising rate between the lowest temperature and 550 ° C. of the molded product in the heat treatment is 5 to 200 ° C./min. It is a manufacturing method of the carbon material interior agglomerate for vertical furnaces of description.

  The “powdered carbon material having softening and melting properties” means coal, SRC, tire chips, plastics, asphalt, tar, log MF (where MF is Giesera maximum fluidity) of 1.0 or more. It is a generic term for powdery substances containing at least one kind of carbonaceous material having softening and melting properties such as ASP and hypercoal. This “powdered carbonaceous material having softening and melting properties” includes carbon having substantially no softening and melting properties such as coke, steaming coal, anthracite, and oil coke, in addition to the carbonaceous material having softening and melting properties. It may be a mixture of one or more substances. “Powdered iron-containing raw material” is a raw material mainly containing iron oxide such as iron ore, iron-making dust (blast furnace dust, converter dust, electric furnace dust, mill scale, etc.), miscellaneous or pellet sieving, or It is a mixture of two or more of these raw materials, and is a generic term for powdered materials.

  According to the present invention, a charcoal obtained by the heat treatment is obtained by heat-treating a molded product of a predetermined size at a higher atmosphere temperature (treatment temperature) than in the past, and in a shorter treatment time than in the past according to the atmosphere temperature. The heat treatment efficiency can be further improved while securing the tar removal rate and strength of the material-incorporated agglomerated minerals. As a result, the heat treatment equipment can be made more compact.

It is a conceptual diagram of the manufacturing flow of the carbonaceous material interior agglomerated for vertical furnace which concerns on implementation of this invention. It is a graph which shows the time change of the surface temperature and center temperature of a molded object at the time of heat processing. It is a graph which shows the relationship between process time and a detarring rate in each atmospheric temperature at the time of heat processing. It is a graph which shows the relationship between the addition rate of an exterior carbon material, and the carbon content in the molding after heat processing. It is a flowchart for demonstrating the behavior of tar at the time of using a carbonaceous material agglomerated ore as a charge of a blast furnace.

(Embodiment)
The conceptual diagram of the manufacturing flow of the carbonaceous material interior agglomerated for vertical furnace which concerns on FIG. 1 at one Embodiment of this invention is shown. Hereinafter, powdered iron ore will be described as a representative example as a powdered iron-containing raw material. Among the carbon materials, a carbon material having soft melting property (for example, caking coal, SRC, etc.) is 1 mm in order to maintain a good mixed state with the powdered iron ore and the carbon material substantially not having soft melting property. It is desirable to grind to the following extent. Moreover, in order to improve the filling property with the above-mentioned softening and melting carbonaceous material, iron ore and a carbonaceous material that does not substantially have softening and melting property (for example, coke powder, general coal, anthracite, oil coke). Etc.) should be crushed and used if necessary. Although the upper limit of the pulverized particle size is a particle size that can be molded, the lower limit is not particularly limited, but it is preferably about the same as that of a carbon material having softening and melting properties.

[Carbon dry drying process]
The powdery carbon material A thus adjusted in particle size is dried and heated at a temperature of, for example, 350 ° C. or less at which the carbon material A does not substantially soften and melt in the carbon material drying and heating equipment (for example, rotary dryer) 1. , Remove adhering moisture.

[Raw material heating process]
On the other hand, the powdered iron ore B has a raw material heating facility (for example, a rotary kiln) 2 of 400 to 400 ° C. so that the target temperature (hot forming temperature) is 250 to 500 ° C. when mixed with the powdered carbonaceous material A. Preheat to a suitable temperature in the range of 800 ° C. As fuel injected from the burner of the rotary kiln 2, pulverized coal that is solid fuel, heavy oil that is liquid fuel, natural gas that is gaseous fuel, COG, or the like can be used.

[Mixing process]
The mixing of the dried powdered carbon material A and the preheated powdered iron ore B is short as a mixing facility in order to suppress unnecessary granulation due to mineralization and / or softening of the carbonaceous material. For example, a bowl-shaped mixing tank 3 that is commonly used in this type of industry that can be mixed with time is used. In addition, this bowl-shaped mixing tank 3 is insulated and / or kept warm in order to ensure the molding temperature.

[Hot forming process]
The mixture C composed of the powdered carbon material A and the powdered iron ore B is pressure-molded by using, for example, a hot-roll twin roll molding machine 4 as a molding facility, and has a volume of 6 to 12 cm ³ (sphere equivalent diameter 23 To 29 mm). The reason why the volume of the molded product D is 6 to 12 cm ³ is that if the size of the molded product D is made too small, the production speed of the molded product D by the molding machine 4 decreases, and the mass of burrs per molded product D When the ratio is increased and the production yield of the molded product D, and hence the carbonaceous material agglomerated ore E is reduced, if the size of the molded product D is made too large, it takes time to remove tar in the next heat treatment step. This is because the processing efficiency decreases.

  The pressure molding is of sufficient strength that the carbonaceous agglomerated ore E obtained by heat-treating the molded product D can withstand handling from the molding machine 4 to the vertical furnace (eg, blast furnace). The molding pressure is set to 10 kN / cm or more so that a certain 0.5 kN / piece or more is obtained.

  In the molded product D thus molded, the melted softening and melting carbon material A enters the voids of the powdered iron ore B, and this carbon material A acts as a lubricant to form the molded product D. Since the molding pressure applied to the surface of the material extends almost uniformly to the inside of the molded product D, it is prevented that only the vicinity of the surface is consolidated, the porosity distribution in the molded product D is averaged, and during heating, Carbonaceous material agglomerated ore E without explosion is obtained.

  In addition, the carbonized material A after solidification firmly connects the particles of the powdered iron ore B and has a large contact area with the powdered iron ore B. Agglomerate E has high strength and excellent reducibility.

[Heat treatment process]
This molded product D is charged into a heat treatment facility (for example, a shaft furnace) 5, the atmospheric temperature T (unit: ° C.) is over 800 ° C. and not more than 1300 ° C., and the processing time t (unit: min) is 1200 / T˜. Heat treatment is performed under the condition of 2400 / T. As a result, the tar content in the molded product D is sufficiently removed, and a carbonaceous material-containing agglomerated mineral E that does not cause troubles such as sticking of tar to the exhaust gas system even when charged in a vertical furnace is obtained. .

  As described above, the atmospheric temperature T (unit: ° C.) is set to be higher than 800 ° C. and not higher than 1300 ° C. If the temperature is 800 ° C. or lower as in the prior art, the processing time cannot be shortened sufficiently, so that the heat treatment equipment 5 is not compact. On the other hand, when the temperature exceeds 1300 ° C., the reduction of the powdered iron ore B by the carbonaceous material A excessively proceeds in the molded product D, and the iron ore becomes spongy metallic iron. This is because the strength of the resulting carbonaceous material-containing agglomerated mineral E decreases as it becomes porous. A preferable range of the atmospheric temperature T is 900 to 1200 ° C, and a more preferable range is 1000 to 1100 ° C.

  The reason for setting the processing time t (unit: min) to 1200 / T to 2400 / T is as follows. That is, if the processing time t is shortened, tar removal from the molded product D is insufficient, and troubles such as sticking of tar to the exhaust gas system of the vertical furnace are likely to occur. On the other hand, if the treatment time t is lengthened, it is preferable from the viewpoint of tar removal from the molded product D, but in addition to the reduction of the treatment efficiency, the reduction reaction of the powdered iron ore by the carbonaceous material in the molded product D is excessive. Proceeding (see below), the iron ore becomes spongy metallic iron, the molded product D becomes porous, and the strength of the obtained carbonaceous material agglomerated ore E decreases.

Here, as shown in FIG. 2, when the molded product (volume: 6 to 8 cm ³ ) is heated at an ambient temperature of 600 ° C., the center temperature of the molded product substantially matches the surface temperature after completion of the temperature increase. On the other hand, when the molded product is heated at an ambient temperature of 800 ° C., the center temperature of the molded product remains at a constant temperature (about 30 ° C.) lower than the surface temperature even after the temperature rise is completed. This is because, when the temperature is 800 ° C. or higher, in the molded product, first, a direct reduction reaction that does not require the supply of a reducing gas: FexOy + yC → xFe + yCO: Formula (1) occurs, and then CO generated by Formula (1) above Gas reduction reaction by: FexOy + yCO → Fe + yCO ₂ Formula (2) proceeds, and further, CO ₂ generated by Formula (2) above is converted into a gasification reaction by carbonaceous material: CO ₂ + C → 2CO ₂ Formula (2) It is shown that the reduction with endotherm proceeds as an overall reaction by regenerating to CO and repeating the reaction cycle of the above formulas (2) and (3). Therefore, as described above, it can be seen that the reduction proceeds excessively if the treatment time t is too long at an atmospheric temperature exceeding 800 ° C.

Therefore, in consideration of these matters, a detarring rate of 50 to 90% can be obtained at which the tar is removed to such an extent that there is no problem even if it is charged into the vertical furnace at each atmospheric temperature using FIG. The range of the processing time t was obtained. Here, FIG. 3 shows that a compact (volume: 6-8 cm ³ ) obtained by hot-molding 20 parts by mass of coal with a tar generation amount of 4% by mass into 80 parts by mass of iron ore using a small heating furnace. This shows the results of an investigation of the behavior of tar removal from a molded product by performing various heat treatment experiments under various nitrogen atmospheres. Here, the detarring rate is an index indicating how much of the tar content in the molded product before heat treatment has been removed.

  As a result of the heat treatment experiment, when the ambient temperature T = 800 ° C., the range of the treatment time t at which a detarring rate of 50 to 90% is obtained is 1.5 to 3.0 min, and when the ambient temperature T = 1000 ° C. The range of the treatment time t at which a detarring rate of 50 to 90% was obtained was 1.2 to 2.4 min. From this result, when the atmospheric temperature T is in the range of more than 800 ° C. and 1300 ° C., the atmospheric temperature T (unit: ° C.) and the processing time t (unit: min) at which a detarring rate of 50 to 90% is obtained are inversely proportional. The processing time t (unit: min) at which a detarring rate of 50 to 90% is obtained with respect to the atmospheric temperature T (unit: ° C.) is 1200 / T to 2400 / T. did. In order to increase the detarring rate more reliably, the lower limit of the processing time t is preferably 1600 / T, and more preferably 2000 / T.

  In this way, after the hot forming, the carbonaceous agglomerated mineral E from which the tar content has been sufficiently removed by further heat treatment is charged into the vertical furnace and heated. The occurrence of troubles such as sticking of tar to the vertical furnace exhaust gas system can be prevented more reliably.

Further, when the interior carbon material B existing in the vicinity of the surface of the molded product D during the heat treatment is consumed by an oxidizing gas (gas containing O ₂ , CO ₂ , H ₂ O, etc.) such as air or combustion gas, it becomes a binder. Therefore, the heat treatment is preferably performed in a non-oxidizing gas atmosphere using nitrogen gas or the like, as in the conventional case.

  However, in order to heat-treat the molding D in a non-oxidizing gas atmosphere, for example, the temperature of the non-oxidizing gas is increased in a heat exchanger using the sensible heat of the combustion gas and then introduced into a heat treatment apparatus. However, it is conceivable that the heat treatment apparatus is of an external heating type, but the apparatus becomes complicated and the equipment cost increases.

  Therefore, the present inventor conducted various studies on methods for directly heating a molded product in a high-temperature oxidizing gas atmosphere such as combustion gas as a method that can further reduce the equipment cost of the heat treatment apparatus. It was found that by adding a predetermined amount of the exterior carbonaceous material F to the case, even when heated in an oxidizing gas atmosphere, the same effect as that obtained when heated in a non-oxidizing gas atmosphere can be obtained.

FIG. 4 shows that molding is performed while the atmospheric temperature in the small heating furnace is 800 ° C. and an oxidizing gas (O ₂ : 5% by volume, CO ₂ : 20% by volume, N ₂ : 75% by volume) is circulated as the atmospheric gas. The result of measuring the carbon content in the molded product (carbonaceous material agglomerated minerals) after heat treatment by sequentially changing the addition rate of the exterior carbonaceous material to the product (volume: 6-8 cm ³ ) and treating for 3 minutes. Is shown. In the figure, the atmosphere temperature and the treatment time are the same as described above, and the molding after heat treatment is performed in the case where the non-oxidizing gas nitrogen gas is used as the atmosphere gas and only the molded product (without the carbonaceous material exterior) is heat treated. The carbon content in the product (carbon material interior agglomerated minerals) is also shown. Here, the addition rate of the exterior carbon material is defined by the ratio of the mass of the exterior carbon material to the mass of the molded product.

  From the figure, when heated in an oxidizing gas atmosphere, when no external carbon material is added, compared to heating in an inert gas atmosphere, in the molded product (carbon material interior agglomerate) after heat treatment It can be seen that the carbon content of the product decreases by 3% by mass. And as the addition rate of the exterior carbon material is increased, the carbon content in the molded product (carbon material interior agglomerated mineral) after the heat treatment approaches when heating in an inert gas atmosphere. It can be seen that the carbon content is 10% by mass or more, and a carbon content almost equivalent to that of heating in an inert gas atmosphere can be obtained. In addition, when the addition rate of the outer carbon material exceeds 20% by mass, the tendency for the carbon content to be slightly higher than the heating in the inert gas atmosphere is given priority to the removal of volatile matter from the outer carbon material. This is thought to be because the removal of volatiles from the charcoal material was delayed and the carbon residue increased accordingly.

  From this result, it was found that when the heat treatment was performed in an oxidizing atmosphere at an atmospheric temperature of 800 ° C., it is preferable to coat the molded product with 10% by mass or more of carbonaceous material.

Here, assuming that the molded product (apparent density 2.6 g / cm ³ ) is a sphere, and assuming a state where a cylindrical space having the same diameter as the sphere is filled with the molded product, the void around the molded product is One third of the cylindrical space. About 11% by mass ([0.6 × 1/3] ÷ [2.6 × 2/3]) ≈0.11 in order to fill the voids with the outer carbon material (bulk density 0.6 g / cm ³ ) ) Is required. Therefore, the exterior carbon material addition rate of 10% by mass or more corresponds to a state in which the surface of the molded product is almost completely covered with the exterior carbon material.

  Therefore, even when the atmospheric temperature is higher than 800 ° C. (1300 ° C. or lower), it can be assumed that the same effect as that obtained when the atmospheric temperature is 800 ° C. can be obtained by covering the molded product with 10% by mass or more of carbonaceous material. .

  However, if the exterior carbonaceous material is added excessively, heat transfer to the molded product is delayed and tar removal becomes insufficient, so it is preferable to keep the addition to 20% by mass or less. The type of exterior carbon material is not particularly limited, but non-caking coal or coke with low fluidity is used so that it can be easily separated from the molded product (carbon material agglomerated mineral) after heat treatment and reused. Is recommended. In addition to preferentially reacting with the oxidizing gas over the interior carbon material, the exterior carbon material does not scatter with the atmospheric gas flow, and can be easily classified as a molded product (carbon material interior agglomerate). Thus, the average particle size is preferably about 0.2 to 6 mm, and more preferably about 0.5 to 3 mm.

  Here, the molded product D that has been pressure-molded by the molding machine 4 in the hot molding process is charged into the heat treatment equipment 5 of the heat treatment process, which is the next process, and the molded product D is transported during that time. The temperature decreases to a predetermined temperature. Then, the molded product D is charged into the heat treatment facility 5 and heated from the predetermined temperature to the ambient temperature T in the heat treatment facility 5. If the predetermined temperature is too low, excessive thermal stress is generated inside the molded product D during the temperature lowering process and / or the temperature raising process up to the ambient temperature T, and cracks are likely to occur in the molded product D. The strength of the carbonaceous material-incorporated agglomerate E decreases.

  Therefore, it is preferable that the temperature of the molded product after the hot forming to before the heat treatment is the hot forming temperature −100 ° C. or higher and 250 ° C. or higher.

  In order to realize this, for example, the conveying pipe from the molding machine 4 to the heat treatment equipment 5 may be as short as possible and / or kept warm. Alternatively, a surge hopper having a heat retaining function may be provided between the molding machine 4 and the heat treatment equipment 5, and the molded product D may be temporarily held in the surge hopper so as not to fall below the minimum temperature.

  In addition to the above, it is preferable that the average rate of temperature increase between the minimum temperature and 550 ° C. of the molded product D in the heat treatment equipment 5 (that is, during the heat treatment) is 5 to 200 ° C./min. Here, the average temperature rising rate between the lowest temperature and 550 ° C. was defined as the average temperature rising rate of the molded product D because the caking property of the carbonaceous material decreased due to the temperature drop to the minimum temperature, and thereafter This is because it is estimated that the temperature range is most likely to cause cracks due to thermal stress in the heating process up to 550 ° C. Moreover, the reason for setting the average rate of temperature rise to 5 to 200 ° C./min is that if the temperature is less than 5 ° C./min, the time required for the heat treatment becomes too long and the productivity is lowered, whereas it exceeds 200 ° C./min. Then, the temperature difference between the surface and the inside of the molded product D is enlarged, the thermal stress becomes excessive, and the molded product D is likely to be cracked.

  In order to realize this, for example, the ambient temperature in the heat treatment equipment 5 may be gradually increased to T instead of T at once.

(Modification)
In the above embodiment, an example in which a shaft furnace is used for the heat treatment process has been shown. However, a rotary kiln, a rotary hearth furnace, an external heating multi-cylinder kiln, a batch furnace, or the like may be used, and a plurality of these may be used in combination. Also good.

  In order to confirm the effect of the present invention, heat treatment experiments were performed on the molded products as shown in Examples 1 and 2 below.

[Example 1]
As raw materials, powdered coal shown in Table 1 and powdered iron ore shown in Table 2 were used. In addition, the particle size of the powdered coal was 74 μm or less and about 60 to 80% by mass, and the particle size of the powdered iron ore was −3 mm and 100% by mass.

Then, powdered coal and powdered iron ore are mixed at a mass ratio of 20:80, and this mixture is supplied to a twin roll molding machine at a temperature of 400 to 450 ° C., and a roll rotation speed of 4 to 8 rpm and a molding pressure of 10 are used. Molded into 30 mm × 25 mm × 17-20 mm almond-shaped briquettes (molded product) under the condition of ˜50 kN / cm. The volume of one briquette is 6-8 cm ³ and its tar content is 0.8% by mass.

  The tar content in the molded product was calculated from the amount of tar generated from the powdered coal and the blending ratio of the powdered coal in the molded product. Here, the amount of tar generated from powdered coal is raised to 1000 ° C. at 5 ° C./min, the generated gas when 120 min dry distillation is cooled to about 30 ° C., and the recovered aggregate is benzene extracted. Asked.

  The heat treatment furnace has a structure in which a heating chamber and a combustion chamber are separated by a partition wall, and heat is supplied to the molded product charged in the heating furnace by conduction and radiation from the partition wall.

[Case 1: Non-oxidizing gas, 600 ° C, no external carbon]
The residence time (processing time) of the molded product in the heating chamber without adding exterior carbonaceous material under the condition of an atmospheric temperature of 600 ° C. in a state where nitrogen gas, which is a non-oxidizing gas, is circulated in the heating chamber. When heat treatment was performed at 5, 10, and 15 minutes, 62, 82, and 90% detarring rates were obtained, respectively. Moreover, the crushing strength of the molded product (carbonaceous material agglomerated mineral) after heat treatment is equivalent to 160-210 kgf / piece (average 180 kgf / piece) with respect to 150-200 kgf / piece (average 170 kgf / piece) before heat treatment. It rose slightly. Here, 1 kgf = 9.80665N.

[Case 2: Non-oxidizing gas, 800 ° C., no exterior carbonaceous material]
Similarly, in a state where nitrogen gas, which is a non-oxidizing gas, is circulated in the heating chamber, the residence time (treatment time) of the molded product in the heating chamber without adding outer carbon material under the condition of an atmospheric temperature of 800 ° C. in the heating chamber. ) When the heat treatment was performed at 1, 3, 5 min, 28, 90, and 94% detarring rates were obtained, respectively. Further, the crushing strength of the molded product (carbonaceous material agglomerated mineral) after the heat treatment was the same as that before the heat treatment in the treatment time of 1 and 3 min, as in the case of the ambient temperature of 600 ° C. In 5 minutes, it became 120-180 kgf / piece (average 140 kgf / piece), and the tendency to fall from before heat processing was recognized.

[Case 3: Oxidizing gas, 800 ° C., no exterior carbonaceous material]
Addition of exterior carbon material under conditions of atmospheric temperature of 800 ° C. in the heating chamber with oxidizing gas (O ₂ : 5 vol%, CO ₂ : 20 vol%, N ₂ : 75 vol%) in the heating chamber When the heat treatment is performed at a residence time (treatment time) of 1, 3 and 5 minutes in the heating chamber without deteriorating, the detarring rates are 28, 90 and 94%, respectively, and the non-oxidizing gas atmosphere of case 2 is obtained. However, the crushing strength of the molded product (carbonaceous material agglomerated mineral) after the heat treatment is equivalent to that before the heat treatment at the treatment time of 1 min, and 120 to 180 kgf / piece (average of 140 kgf / piece) at the treatment time of 3 min. ), A treatment time of 5 min was 100 to 140 kgf / piece (average of 120 kgf / piece), and the tendency for the decrease from before the heat treatment to increase as the treatment time increased was observed.

[Case 4: Oxidizing gas, 800 ° C., using exterior carbon]
In the case 3, when 15% by mass of the outer carbon material is added to the molded product and the other conditions are heat-treated under the same conditions as in the case 3, the detarring rate is the case of the non-oxidizing gas atmosphere of the case 2 While maintaining the same, the crushing strength of the molded product (carbon material agglomerated ore) after heat treatment is 150-200 kgf / piece (average 170 kg / piece), which is the same strength as before the heat treatment and suppresses strength reduction. did it. In addition, the carbonaceous material used for the exterior is a coke powder having a volatile content of 0.0%, an ash content of 12.0%, and fixed carbon of 88.0% by mass%.

[Example 2]
In this example, a rotary hearth furnace was used as a heat treatment apparatus, and the same molded product as that in Example 1 was heat-treated. This rotary hearth furnace has a burner in the furnace and radiates and heats an object to be processed with the combustion heat, and the inside of the furnace is an oxidizing gas atmosphere. When 15% by mass of the outer carbonaceous material is added to the molded product, it is placed in a furnace having an atmospheric temperature of 800 to 900 ° C., and heat-treated with a residence time (processing time) of 2 min. As for the (mineralization), a detarring rate of 90% was obtained while ensuring the same crushing strength as before the heat treatment.

[Example 3]
In this example, after the hot forming, various setting times until the heat treatment were changed, and the minimum temperature of the molded product after the hot forming and before the heat treatment, and the minimum temperature of the molded product during the heat treatment, Varying the average heating rate between 550 ° C and measuring the crushing strength of the molded product before heat treatment and the molded product after heat treatment (carbonized material agglomerate), change in crushing strength of the molded product by heat treatment investigated.

  The survey results are shown in Tables 3 and 4 below. In Table 3, the lowest temperature was 250 ° C. or higher.

  From the investigation results shown in Table 3, it can be seen that the minimum temperature of the molded product after hot forming to before heat treatment is recommended to be hot forming temperature −100 ° C. or higher and 250 ° C. or higher.

Moreover, from the investigation results shown in Table 4, it can be seen that it is further recommended that the average temperature increase rate between the lowest temperature of the molded product and 550 ° C. during the heat treatment is 5 to 200 ° C./min.

1: Carbon material drying and heating equipment (rotary dryer)
2: Raw material heating equipment (rotary kiln)
3: Mixing equipment (vertical mixing tank)
4: Molding equipment (twin roll molding machine)
5: Heat treatment equipment (shaft furnace)
A: Powdered carbon material (powdered coal)
B: Powdered iron-containing raw material (powdered iron ore)
C: Mixture D: Molded product (briquet before heat treatment)
E: Carbonaceous agglomerate (briquet after heat treatment)
F: Exterior carbon material

Claims (5)

A molded product having a volume of 6 to 12 cm ³ produced by hot forming a mixture of powdered iron-containing raw material and powdered carbon material having soft melting property at a hot forming temperature of 250 to 500 ° C. is further formed. After adding 10 to 20% by mass of the exterior carbonaceous material to the product, the atmosphere temperature T (unit: ° C.) is over 800 ° C. and not more than 1300 ° C. in the oxidizing gas atmosphere , and the processing time t (unit: min) is a heat treatment under the conditions of 1200 / T to 2400 / T to remove the tar content in the molded product, thereby obtaining a carbonaceous material-containing agglomerate. Method for producing ore. A molded article having a volume of 6 to 12 cm ³ produced by hot forming a mixture of powdered iron-containing raw material and powdered carbon material having soft melting property at a hot forming temperature of 250 to 500 ° C. Charcoal is obtained by performing a heat treatment under the conditions (unit: ° C.) higher than 800 ° C. and lower than 1300 ° C. and processing time t (unit: min) of 1200 / T to 2400 / T to remove the tar content in the molded product. In obtaining the material-incorporated agglomerated mineral, the minimum temperature of the molded product after the hot forming to before the heat treatment is the hot forming temperature −100 ° C. or more and 250 ° C. or more. A method for producing coal-type agglomerates for vertical furnaces. The manufacturing method of the carbonaceous material interior agglomerate for vertical furnaces of Claim 2 which performs the said heat processing in non-oxidizing gas atmosphere. The method for producing a vertical furnace carbonaceous material-incorporated agglomerated mineral according to claim 2 , wherein 10-20% by mass of an exterior carbonaceous material is added to the molded product when the heat treatment is performed in an oxidizing gas atmosphere. The vertical carbonaceous material interior for vertical furnaces according to any one of claims 2 to 4 , wherein an average temperature rising rate between the lowest temperature and 550 ° C of the molded product in the heat treatment is 5 to 200 ° C / min. A method for producing agglomerates.

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