JP2007211271A - Method and equipment for manufacturing carbonaceous-material-containing agglomerate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing carbonaceous-material-containing agglomerates by which, when preparing a mixture of a powdery iron containing raw material and a powdery carbonaceous material having softening and melting properties, a raw material yield and an energy efficiency can be improved by decreasing the scattering loss of raw material powder using simple facilities. <P>SOLUTION: A dried powdery iron containing raw material B and a carbonaceous material B having softening and melting properties are mixed under heating in a vertical mixing tank 3 to prepare a mixture C of 250 to 550°C. The mixture C is hot formed using a twin-roll type forming machine 4, and the resultant formed material D is held in a shaft furnace 5 at a temperature between hot forming temperature to 800°C to remove volatile components and tar components remaining in the formed material. By this method, the carbonaceous-material-containing agglomerates E can be obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for producing an agglomerated carbonaceous material agglomerated material that can be used as a raw material for vertical furnaces such as blast furnaces and cupolas.

  The present inventors hot-mold a mixture of fine ore (a powdered iron-containing raw material) and a soft and meltable carbon material for the purpose of using as a raw material for vertical furnaces such as blast furnaces and cupolas. Has developed an agglomerated carbonaceous material agglomerate that can provide high strength without the addition of a binder such as cement, as in the case of conventional cold pellets with an internal carbonaceous material.

  Such a carbonaceous material agglomerated material can be produced, for example, by a process as shown in FIG. That is, the powdered iron ore B was heated to 400 to 800 ° C. with the rotary kiln 102, and the powdered carbon material A having soft melting property was separately dried at a temperature of less than 250 ° C. at which the softening and melting did not occur with the rotary dryer 1. After that, the powdered carbon material A and the powdered iron ore B are mixed by a biaxial mixer 103 to obtain a mixture C of 250 to 550 ° C., which is a temperature at which the powdered carbon material A is softened and melted. And the carbonaceous material agglomerate E is obtained by carrying out the hot forming of this mixture C with the twin roll type molding machine 4, and briquetting (refer patent document 1, 2).

  In the above method (apparatus), the technical idea is to raise the temperature of the mixture C using the sensible heat of the pulverized iron ore B, but it has been found that the following problems arise due to the investigations by the inventors. .

  That is, when a powdered carbon material having softening and melting properties such as powdered coal is mixed with a high-temperature powdered iron ore heated to 400 to 800 ° C., a part of the carbon material particles rapidly rise in temperature. Since the volatile component is rapidly gasified and released at once, the mixed powder bumps into the raw material powder (which means a generic term for powdered iron ore and powdered carbonaceous material. "Material" also has the same meaning). It was found that a large amount of gas was scattered and gas was involved in the mixed powder, which hindered heat transfer from the powdered iron ore to the powdered carbonaceous material, resulting in a decrease in raw material yield and energy loss.

Although the scattered raw material powder can be recovered and used again as a raw material, the yield of the raw material can be improved. However, a separate process (equipment) for recovering the raw material powder is required, which complicates the process and reduces the equipment cost. There is a problem that leads to a rise.
Japanese Patent No. 3502011 Japanese Patent No. 3502008

  Therefore, the present invention, when producing a mixture of powdered iron-containing raw materials such as powdered iron ore and powdered carbon materials having soft melting properties such as powdered coal, scattering of the raw material powder with simple equipment It aims at providing the manufacturing method of the carbonaceous material agglomerate which can improve raw material yield and energy efficiency by reducing loss.

  The invention according to claim 1 is a heating and mixing step in which a powdered iron-containing raw material and a powdered carbon material having softening and melting properties are heated and mixed to form a mixture at 350 to 550 ° C., and the mixture is heated. A method for producing an agglomerated carbonaceous material agglomerated material comprising a hot forming step of forming a carbonized material agglomerated material.

  Invention of Claim 2 is a manufacturing method of the carbon material interior agglomerated product of Claim 1 which sets the processing time in the said heating and mixing process to 10 to 120 s.

  The invention according to claim 3 is a heating process in which a powdery iron-containing raw material and a softened and meltable powdered carbon material are mixed while being heated for a treatment time of 10 to 120 s to produce a mixture at 350 to 550 ° C. An apparatus for producing an agglomerated carbonaceous material agglomerated material, comprising a mixing facility and a molding facility for hot-molding the mixture to produce an agglomerated carbonaceous material agglomerated material.

  “Powdered carbon material having soft melting property” means coal, SRC, tire chip, plastic, asphalt, tar, etc. whose log MF (where MF is Giesera maximum fluidity) is 1.0 or more. It is a generic term for powders that contain at least one carbonaceous material having soft melting properties. 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” means a raw material mainly containing iron oxide such as iron ore and iron-making dust (blast furnace dust, converter dust, electric furnace dust, mill scale, etc.), or two or more of these raw materials It is a general term for a mixture of powders.

  According to the present invention, when preparing a mixture of a powdered iron-containing raw material and a soft powdery carbonaceous material, a high-temperature powdered iron-containing raw material is mixed into the powdered carbonaceous material as in the past. Instead, the powdered iron-containing raw material and the powdered carbonaceous material are heated to a predetermined temperature while being mixed, so that the carbonaceous material particles are heated uniformly and the rapid gasification of volatile matter is suppressed. As a result, the yield of the raw material and the energy efficiency are greatly improved by suppressing the scattering of the raw material powder and suppressing the entrainment of gas in the mixed powder and improving the heat transfer efficiency. It was.

(Embodiment)
FIG. 1 shows a conceptual diagram of a manufacturing flow of a carbonaceous material-incorporated agglomerated product (hereinafter also simply referred to as “agglomerated product”) 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. 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 material drying heating process]
The powdery carbonaceous material A thus adjusted in particle size is dried and heated at a temperature of 350 ° C. or less at which the carbonaceous material A is not substantially softened and melted in the carbonaceous material drying heating facility (for example, a rotary dryer) 1. Remove adhering moisture. Here, the drying heating temperature of the powdered carbon material A was “less than 250 ° C.” in which the carbon material is not softened and melted in the prior art (see Patent Documents 1 and 2). Even when the drying heating temperature was raised to “° C.”, it was found that the carbonaceous material was not substantially softened and melted.

[Ore drying heating process]
Further, the powdered iron ore B is also dried and heated at a temperature of 350 ° C. or less with an ore drying heating facility (for example, a rotary dryer) 2 to remove adhering moisture. Here, the reason why the drying heating temperature of the powdered iron ore is set to 350 ° C. or less is to prevent the powdered carbonaceous material from rapidly softening and melting when mixed with the powdered carbonaceous material.

[Heat mixing process]
For mixing the dried powdered carbon material A and the powdered iron ore B, as a heating and mixing facility, a short time is required 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 can be used. The vertical mixing tank 3 is provided with, for example, an external heating type heating mechanism in order to heat the mixture C to a molding temperature of 350 to 550 ° C.

  The treatment time in the vertical mixing tank 3 is preferably in the range of 10 to 120 s. If it is less than 10 s, the mixing time is insufficient and a homogeneous mixture cannot be obtained, and degassing from the mixture becomes insufficient, so that the molding pressure is not sufficiently transmitted to the mixture during the hot forming of the next step. The agglomerated material is likely to crack or lack strength. On the other hand, if it exceeds 120 s, the mixture is sufficiently degassed, but the carbonaceous material as the binder softened and melted by heating aggregates and fuses together to form a large lump. Elimination of the agglomerated material is likely to be hindered due to the presence of such large lumps and the molding pressure not being sufficiently transmitted during the subsequent hot forming. On the other hand, when the processing time is in the range of 10 to 120 s, a homogeneous mixture is obtained, deaeration is sufficiently performed, large lumps are not generated, and a function of the carbonaceous material as a binder is sufficiently obtained. Therefore, the molding pressure is sufficiently transmitted at the time of hot forming in the next step, and a high-strength agglomerated product is obtained.

[Hot forming process]
The mixture C composed of the powdered carbon material A and the powdered iron ore B thus obtained is pressure-molded using, for example, a hot roll twin-roll molding machine 4 as a molding facility, and a molded product D And The pressure molding has a strength sufficient to allow the agglomerate E obtained by heat-treating the molded product D to withstand handling from the molding machine 4 to charging into a vertical furnace (for example, a blast furnace). The molding pressure is set to 10 kN / cm or more so that 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, An agglomerate E in which no explosion occurs 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, and the agglomerates obtained in this way. E has high strength and excellent reducibility.

[Heat treatment process]
The molded product D was charged into a heat treatment facility (for example, a shaft furnace) 5 adjusted to a temperature of the hot molding temperature (250 to 550 ° C.) or higher and 800 ° C. or lower, and the volatile matter remaining in the molded product D and Remove tar and solidify charcoal. Thereby, when the agglomerated product E obtained by heat-treating the molded product D is charged in the vertical furnace and heated, the carbonaceous material is no longer softened and the strength of the agglomerated product E is maintained. In addition, a large amount of tar is not generated, and trouble such as tar sticking to the exhaust gas system of the vertical furnace can be prevented. The lower limit of the temperature in the shaft furnace 5 is set as the molding temperature because if the temperature is lower than the molding temperature, it is very difficult to remove volatile components and tar components, and the upper limit is set to 800 ° C. This is to prevent the strength of the agglomerated material H from being reduced unnecessarily in the shaft furnace 5. Further, in order to promote the removal of volatile matter and tar content, it is one of effective means to control the inside of the shaft furnace 5 to a negative pressure.

  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 rotary dryer 1, the vertical mixing tank 3, the molding machine 4 and the shaft furnace 5 have a structure that prevents the entry of air (oxygen) from the outside, and the pyrolytic gas (volatilization) of the carbonaceous material A generated in these facilities. Since the main component is hydrocarbon, the gas is sucked and recovered using an ejector or the like, and the recovered gas is used as a heating fuel for the rotary kiln 2 or the like. In addition, since harmful components such as dust and high boiling point tar are contained in this gas, it is desirable to use it after dust removal and cleaning by an exhaust gas treatment facility (for example, a water-resistant scrubber) 9.

(Modification)
In the above embodiment, the rotary dryer is exemplified as the carbonaceous material drying heating equipment and the ore drying heating equipment, but a fluidized bed dryer, a tube dryer, an externally heated multi-cylinder rotary dryer, an airflow dryer, a fluidized bed dryer, etc. You may use, and you may use combining these two or more.

  Moreover, in the said embodiment, although the example which provided both the carbonaceous material drying heating equipment and the ore drying heating equipment was shown, these equipment is not necessarily essential equipment, and only one or both may be provided. Both can be omitted.

  In the above embodiment, the vertical mixing tank is exemplified as the heating and mixing equipment, but a horizontal container rotating mixer (such as a drum mixer) or a horizontal container fixed shaft mixing mixer (for example, a paddle mixer or a ribbon mixer) is used. These may be used in combination. In addition to the continuous mixing method, a batch type mixing method in which a hopper is installed upstream of the mixing tank and operated intermittently may be adopted. Also good.

  Further, in the above embodiment, the external heating type is illustrated as the heating mechanism of the vertical mixing tank, but an internal heating type using combustion gas or the like as a heat source may be used.

  Moreover, in the said embodiment, although the twin roll type molding machine was illustrated as a shaping | molding equipment, you may use a tableting machine etc.

  Moreover, in the said embodiment, although the combination of the vertical mixing tank and the twin roll type | mold molding machine was illustrated, it replaces with this combination and is continuous after mixing a powdered iron ore and a powdered carbonaceous material while heating. Extruders (for example, single-screw kneading extruders and multi-shaft kneading extruders) equipped with an external heating type heating mechanism that are compressed and extruded into the same, and the extruded products are cut into predetermined lengths. You may comprise by the combination with the cutter which produces a carbon material interior agglomerate.

  In the above embodiment, the shaft furnace is exemplified as the heat treatment equipment. However, the rotary kiln, the rotary hearth furnace, the external heating type multi-tube kiln, the external heating type and / or the internal heating type horizontal container fixed shaft rotary heating furnace. A batch furnace or the like may be used, or a combination of these may be used.

  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.

  Moreover, although the example which provided the cooling part in the lower part of the shaft furnace was shown in the said embodiment, you may provide cooling equipment separately from a shaft furnace.

  The carbonaceous agglomerate according to the present invention is assumed to be used as a raw material for vertical furnaces such as blast furnaces and cupolas, that is, used as an iron source. Manufacture by increasing the blending ratio of the contained raw materials. However, it is clear that an agglomerate can be produced by the method of the present invention even if the blending ratio of the powdered carbonaceous material is higher than that of the powdered iron-containing raw material. The agglomerated material having a high carbonaceous material blend ratio obtained in this manner can be used by being charged into a coke oven as a raw material for producing ferro-coke.

[Invention Example 1]
In order to confirm the effect of the present invention, the following laboratory experiment was conducted. As the powdered iron ore, the one obtained by sieving the riodoce ore sinter feed (riodose SF) to 1.4 mm or less was used. On the other hand, as the powdery coal, coal having a fluidity of logMF = 3.4 pulverized to 1 mm or less with a ball mill was used.

Then, about 15 g of powdered iron ore and about 4 g of powdered iron ore are charged into an iron container (inner diameter 20 mm, height 40 mm) wound around an electric heater and held at 420 ° C., and a thermocouple is used as a stirring rod. Various mixing times (corresponding to the processing time in the heating mixer) were changed between 15 to 120 s, and the mixture was stirred and mixed to prepare a mixture, which was immediately subjected to a molding pressure of 800 kgf / cm ² (≈ It was molded into a tablet-like carbon material agglomerate having a diameter d = 20 mm and a height h = 20 mm under a load of 78.5 MPa. Although the temperature of the mixture was measured with the thermocouple used for the stirring and mixing, the heat capacity of the mixture was sufficiently small compared to the heat capacity of the container. Therefore, in the mixing time range (25 to 120 s), the mixing was completed. The temperature of the mixture almost coincided with the container temperature of 420 ° C. before charging the raw materials.

  And after cooling the tablet shape | molded in this way to room temperature, according to the tensile strength test method (JIS-A1113) of concrete, it applies a compressive load to the diameter direction of a tablet with the said crushing strength tester, and destroys The load P was measured and converted into the tensile strength σ in the tablet height direction using the relational expression of σ = 2P / (πdh).

  Here, the crushing strength of briquettes (30 mm x 25 mm x 17 mm oval) prepared by variously changing the types of powdered ore and powdered coal, the blending ratio of powdered ore and powdered coal, molding temperature, etc. As a result of investigating the correlation between the tensile strength of tablets molded at the same molding temperature using the same ingredients and at the same molding temperature, it was confirmed that a strong linear relationship was established between them as shown in FIG. It was done. Therefore, it is clear that the crushing strength of the briquette (agglomerated material) can be evaluated by the tensile strength of the tablet obtained in the laboratory experiment.

FIG. 4 shows the relationship between the mixing time (processing time) in the heating mixer and the tensile strength of the tablet. As shown in the figure, the tablet tensile strength (ie, briquette crushing strength) initially increases with an increase in mixing time, but shows a maximum value at a mixing time of 60 s, and further decreases when the mixing time is extended. I understand. In the mixing time of 15 to 120 s, the tablet has a tensile strength of 5 kgf / cm ² (≈0.5 MPa) or more, and when converted to a briquette crushing strength, 100 kgf (≈1 kN) or more is obtained. . Therefore, as specified in the present invention, the powdered iron ore and the powdered carbon material are mixed with heating at a processing time of 10 to 120 s to form a mixture at 350 to 550 ° C., and this is hot-molded to form a lump. It was found that an agglomerated product having a crushing strength of 50 kgf (0.5 kN) or more, which has no problem in handling at the time of charging into a vertical furnace such as a blast furnace, can be obtained by manufacturing the agglomerated material.

  Moreover, although the recovery rate defined by the following formula (1) was used as an index for evaluating the raw material yield, a recovery rate of 93% was obtained in Example 1 of the present invention, and the scattering loss of the raw material powder during heating and mixing was It was confirmed that the raw material yield was small and high.

  Recovery rate (%) = (Mass of tablet) / (Mass of powdered ore + Mass of powdered coal) × 100 Formula (1)

[Invention Example 2]
Next, while changing the kind of powdered coal variously and changing variously between container temperature 350-500 degreeC and mixing time 30-90s, the laboratory experiment by the same tablet shaping | molding as the said invention example 1 was implemented.

An experimental result is shown in FIG. 5 by the relationship between the fluidity | liquidity of powdered coal, and the tensile strength of a tablet. As shown in the figure, although the tablet tensile strength varies depending on the type of powdered coal, by using powdered coal having a log MF of 1.0 or more, the tablet tensile strength is 3 kgf / cm ² (≈ 0.3 Mpa) or more is obtained. Therefore, when converted to the crushing strength of briquettes (agglomerated materials), 50 kgf (≈0.5 kN) or more is obtained, and a high-strength agglomerated material that does not have a problem in handling during charging into a vertical furnace such as a blast furnace. It was confirmed that it was obtained. Moreover, the recovery rate defined by the above formula (1) is in the range of 90 to 95%, and it was confirmed that a high raw material yield was obtained as in the above-described Invention Example 1.

[Comparative Example 1]
The same raw material combination as in Invention Example 1 was used, the container temperature was 300 ° C., the mixing time was 30 s. Since the temperature of the mixture (that is, the molding temperature) does not reach 350 to 550 ° C. defined in the present invention, it is considered that the function as a binder could not be exhibited due to insufficient softening and melting of powdered coal. .

[Comparative Example 2]
In order to simulate the conventional method in which the temperature of the mixture is raised using the sensible heat of powdered iron ore, the powdered coal is placed in a container maintained at 200 ° C. using the laboratory experimental apparatus and raw material powder used in Invention Example 1 above. After charging, a laboratory experiment was conducted in which powdered iron ore heated to 700 ° C. in another heating furnace was added.

  As a result, immediately after the powdered iron ore was introduced and mixed, gas was blown out, bumping occurred, and a large amount of raw material powder was blown out. The recovery rate defined by the above formula (1) was 70%, which was a very low value as compared with Invention Examples 1 and 2.

  Moreover, since the temperature of the mixture after mixing was 400 ° C., the heat transfer efficiency calculated by the following formula (2) was a very low value of about 30%. The reason why the heat transfer efficiency is extremely low in this way is that most of the raw material powder spilled by bumping is powdered iron ore that should serve as a heat source.

Heat transfer efficiency (%) = [mass of powdered coal × coal specific heat × (400 ° C.−200 ° C.)] / [Mass of powdered iron ore × specific heat of iron ore × (700 ° C.−400 ° C.)] × 100 Formula ( 2)
Here, the specific heat of coal was 1.05 MJ / (kg · K) and the specific heat of iron ore was 0.63 MJ / (kg · K).

It is a conceptual diagram of the manufacture flow of the carbonaceous material interior agglomerate which concerns on implementation of this invention. It is a conceptual diagram of the manufacture flow of the carbonaceous material agglomerate by the conventional method. It is a graph which shows the relationship between the tensile strength of a tablet, and the crushing strength of a briquette. In invention example 1, it is a graph which shows the relationship between mixing time and the tensile strength of a tablet. It is a graph which shows the relationship between the fluidity | liquidity of powdered coal and the tensile strength of a tablet in the example 2 of an invention.

Explanation of symbols

1: Carbon material drying and heating equipment (rotary dryer)
2: Ore drying heating equipment (rotary dryer)
3: Heating and mixing equipment (vertical mixing tank)
4: Molding equipment (twin roll molding machine)
5: Heat treatment equipment (shaft furnace)
9: Exhaust gas treatment facility (Ansui scrubber)
A: Powdered carbon material (powdered coal)
B: Powdered iron-containing raw material (powdered iron ore)
C: Mixture D: Molded product E: Carbon material interior agglomerated material

Claims (3)

  A heating and mixing step of heating and mixing a powdered iron-containing raw material and a soft and meltable powdered carbon material into a mixture at 350 to 550 ° C., and hot-molding the mixture to form an agglomerated carbon material material A method for producing an agglomerated carbonaceous material agglomerated material comprising a hot forming step.   The method for producing an agglomerated carbonaceous material agglomerated product according to claim 1, wherein a treatment time in the heating and mixing step is 10 to 120 s.   A heating and mixing equipment for mixing a powdered iron-containing raw material and a powdered carbonaceous material having softening and melting properties while heating them for a treatment time of 10 to 120 s to produce a mixture at 350 to 550 ° C., and hot mixing the mixture An apparatus for producing an agglomerated carbonaceous material agglomerated material, comprising a molding facility for forming agglomerated carbonaceous material agglomerated material.

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