JP4843445B2 - Manufacturing method of carbonized material agglomerates - Google Patents

Description

  The present invention relates to a method for producing an agglomerated carbonaceous material by hot forming, which can be used as a raw material for vertical furnaces such as blast furnaces and cupolas, and more particularly to a technique for improving thermal efficiency during hot forming. .

  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 the rotary kiln (ore heating equipment) 2, and the powdered carbon material A having softening and melting properties is separately softened and melted by the rotary dryer (coal heating equipment) 1. After drying at a temperature of less than 250 ° C., which does not occur, this powdered carbonaceous material A and powdered iron ore B are mixed with a biaxial mixer 3 and the powdered carbonaceous material A is softened and melted at a temperature of 250 to Mixture C at 550 ° C. And the agglomerate E is obtained by carrying out hot forming of this mixture C with the twin roll type | mold molding machine (molding equipment) 4, and briquetting (refer patent documents 1, 2). Further, if necessary, the molded briquette D is kept in a hot gas forming temperature range or higher in a degassing tank (heat treatment equipment) 5 for a predetermined time, and volatile matter and tar content remaining in the briquette D are removed. You may make it remove almost completely (degassing) (refer patent document 3).

  The above method uses the sensible heat of the powdered iron ore B heated by the rotary kiln (ore heating facility) 2 to increase the temperature to soften and melt the powdered carbonaceous material A in the mixture C. By molding in a softened and melted state, the carbonaceous material and iron ore particles are brought into close contact with each other, and a high-strength carbonaceous material agglomerate E can be obtained without a binder such as cement.

  However, when the above method is put to practical use, the endothermic action accompanying the generation of volatile gas, tar, etc. from the carbon material in the rotary dryer (coal heating equipment) 1, the mixer (mixing equipment) 3 and the molding machine (forming equipment) 4 And the heat loss from the equipment (hereinafter referred to as “heat loss etc.”), the temperature of the mixture C cannot be maintained at a predetermined temperature, the fluidity of the powdered carbon material A is reduced, and the carbon material and the iron ore particles There is a possibility that the adhesiveness of the briquette D deteriorates and the strength of the briquette D decreases. As a countermeasure, it is conceivable that the heating temperature of the powdered iron ore B is set higher in advance, but it is necessary to increase the heat resistance of the rotary kiln 2 and the equipment cost increases. In addition, it is conceivable to increase the heat insulation of the mixer 3 or to keep the mixer 3 externally heated, but the amount of heat insulating material and refractory increases, and additional heating means such as a heater are required. Cost will rise.

  In addition, when degassing is performed from the molded briquette D, it is necessary to heat the briquette D to a molding temperature or higher in a degassing tank (heat treatment equipment) 5, but the specific heating means is clearly shown. However, for example, when a heating means such as a heater is introduced, there is a problem that the equipment cost increases as described above.

  In Patent Document 4, the coal particles are heated in a fluidized bed at about 500 to 900 ° F. (about 260 to 482 ° C.) to remove tar products, and then 1800 ° F. (982 ° C.) or less. It is heated to a high temperature to reduce volatile content to 5% or less and char, and this char is mixed with bituminous binders such as pitch and iron ore-containing materials such as iron ore and formed into raw briquettes. The raw briquette is exposed to a gas (oxygen-containing gas) heated to about 400 ° F. (about 204 ° C.) with an oxygen content of 5 to 21%, preferably at least 15%, and 450-570 ° F. (232-299) inside the briquette. C.) is generated and cured, and further fired at about 1400 to 1600 ° F. (760 to 871 ° C.) to produce a carbonaceous iron briquette (carbon material-containing briquette). .

  However, in the above method, by using an oxygen-containing gas, the bituminous binder and char are reacted in the raw briquette to cause a certain exothermic reaction in the briquette. The technical idea is to integrate them.

On the other hand, the method of the present invention, as will be described later, uses a gas containing oxygen to burn a volatile matter generated from the carbonaceous material, thereby bringing the mixture and / or briquette (agglomerated product) to a predetermined temperature. The technical idea is to minimize the oxidation reaction of the carbonaceous material in the mixture and / or briquette while heating to a predetermined temperature, and the method described in Patent Document 4 is completely technical. It is different.
Japanese Patent No. 3502011 ([0021] to [0024], FIG. 1) JP 2001-294944 A ([0016] to [0019], FIG. 1) JP-A-11-92833 ([0017] to [0018], FIG. 1) JP-A-48-52615 (Claims, page 3, upper right column, line 2 to page, lower right column, bottom line, page 4, lower left column, lines 3 to 11)

  The present invention can easily and reliably maintain at least one of a carbonaceous material, a mixture, and an agglomerated material at a predetermined temperature without heating the equipment cost, or can be heated to a predetermined temperature, greatly increasing thermal efficiency. An object of the present invention is to provide a method for producing an agglomerated carbonaceous material that can be improved.

The invention according to claim 1 is a carbon material heating step of heating a powdered carbon material having softening and melting properties at 350 ° C. or less, a raw material heating step of heating a powdered iron-containing raw material to 400 to 800 ° C., and eggplant a mixing step of a mixture of powdered carbonaceous material and a mixture of a powdered iron-containing raw material after the heating 250 to 550 ° C. after heating, the mixture is hot forming and carbonaceous material interior agglomerates A carbonaceous material-containing lump comprising a hot-forming step and performing a treatment while circulating a gas containing oxygen in at least one of the carbonaceous material heating step, the mixing step, and the hot-forming step. It is a manufacturing method of a chemical compound.

The invention according to claim 2 is a carbon material heating step of heating a powdered carbon material having softening and melting properties at 350 ° C. or lower, a raw material heating step of heating a powdered iron-containing raw material to 400 to 800 ° C., and eggplant a mixing step of a mixture of powdered carbonaceous material and a mixture of a powdered iron-containing raw material after the heating 250 to 550 ° C. after heating, the mixture is hot forming and carbonaceous material interior agglomerates A hot forming step, and a heat treatment step of removing the volatile matter and tar content remaining in the carbonaceous material agglomerated material while maintaining the carbonaceous material agglomerated material at a temperature equal to or higher than the hot molding temperature, A method for producing an agglomerated carbonaceous material-containing agglomerated product, characterized in that in at least one of the carbonaceous material heating step, the mixing step, the hot forming step, and the heat treatment step, treatment is performed while circulating a gas containing oxygen. It is.

  The “powdered carbonaceous material having softening and melting property” includes at least one kind of carbonaceous material having softening and melting properties such as caking coal, non-slightly caking coal, and SRC. It is a generic name. 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, by exposing at least one of the carbonaceous material, the mixture containing the carbonaceous material, and the agglomerated material to a gas atmosphere containing oxygen at a temperature at which the thermal decomposition of the carbonaceous material can proceed. , Volatiles and tars devolatilized from charcoal burn, and at least one of charcoal, mixture, and agglomerate is heated, so it is simple and reliable without extra equipment costs In addition, the mixture and / or the agglomerate can be maintained at a predetermined temperature or heated to a predetermined temperature, and the thermal efficiency is greatly improved.

(Embodiment)
The conceptual diagram of the manufacture flow of the carbonaceous material interior agglomerate which concerns on FIG. 1 at one Embodiment of this invention is shown. 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, powdered iron ore will be described as a representative example as a powdered 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. It is desirable to grind to about 1 mm or less in order to keep the mixed state with the powdered iron ore and the carbonaceous material substantially free of softening and melting property.

[Carbon material heating process]
The powdery carbon material A thus adjusted in particle size is heated at a temperature of 350 ° C. or less at which the carbon material A is not substantially softened and melted by the carbon material heating facility (for example, rotary dryer) 1. At this time, depending on the charcoal type and the heating temperature (for example, 250 ° C. or more), volatile gas may be generated. When volatile gas is generated in this way, for example, air G is circulated as oxygen-containing gas (hereinafter also referred to as “oxygen-containing gas”), and heat treatment is performed in an oxygen-containing gas atmosphere. As a result, all or a part of the volatile matter generated from the powdered carbon material A reacts with the oxygen gas component in the air G and burns to increase the ambient temperature. The target heating temperature can be ensured more reliably by reducing the amount of heating from the outside. Note that the heating temperature of the powdered carbonaceous material A can be easily adjusted by increasing or decreasing the flow rate of the air G (for details, refer to the description of temperature control in the mixing step described later).

[Raw material heating process]
On the other hand, the powdered iron ore B is preheated to 400 to 800 ° C. with an ore heating facility (for example, a rotary kiln) 2 so that the target temperature is 250 to 550 ° C. when mixed with the powdered carbon material A. 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.

  In addition, when iron-making dust (blast furnace dust, converter dust, electric furnace dust, mill scale, etc.) is used by replacing a part of the powdered iron ore B, the iron-making dust contains carbon and metallic iron and burns when preheated. Therefore, the iron-making dust is directly charged into the below-described mixing facility 3 without being charged into the rotary kiln 2 and 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. Further, in order to ensure heat insulation, for example, air is circulated as the oxygen-containing gas G in the bowl-shaped mixing tank 3, and the mixing process is performed in such an oxygen-containing gas atmosphere. As a result, all or part of the volatile matter and tar content generated from the powdered carbonaceous material A (hereinafter collectively referred to as “volatile matter etc.”) reacts with the oxygen gas component in the air G and burns. Since the ambient temperature rises, the temperature of the mixture C, that is, the molding temperature can be ensured more reliably. Note that the temperature of the mixture C can be easily adjusted by increasing or decreasing the flow rate of the air G.

  However, if the flow rate of the air G is too large, the volatile matter generated from the powdered carbonaceous material A is completely burned, and excess oxygen gas components remain in the atmosphere gas after combustion. The fixed carbon content in the carbonaceous material A is oxidized and consumed. Therefore, it is preferable that the amount of oxygen in the air G supplied to the vertical mixing tank 3 is smaller than the chemical equivalent required for complete combustion of the volatile matter generated from the powdered carbon material A. As a result, the oxygen gas component in the air G supplied to the vertical mixing tank 3 reacts preferentially with volatile components and the like and is consumed, and no oxygen gas component remains in the atmosphere gas after combustion. The hydrocarbon gas, which is a main component such as volatile matter, partially remains in the atmosphere without being completely burned. As a result, the atmosphere around the powdered carbonaceous material A is maintained to be reducible, and the fixed carbon content in the powdered carbonaceous material A is prevented or suppressed from being consumed, and the mixture C, that is, the briquette D. The amount of carbon material inside will be secured.

  Further, as the oxygen-containing gas G, 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 vertical mixing tank 3 can be reduced, and the exhaust gas from the vertical mixing tank 3 can be reduced. The amount is reduced and the cost of the exhaust gas treatment facility is reduced. Further, since the exhaust gas from the vertical mixing tank 3 contains pyrolysis gas (volatile matter etc.) mainly composed of hydrocarbons, oxygen gas or oxygen-enriched air is used when using this as fuel. 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 increases.

In addition, when there is a possibility that the temperature locally increases in the vertical mixing tank 3 due to the circulation of the air G, the exhaust gas calorie is further lowered than simply using air, but N ₂ gas or rotary is included in the air. Combustion exhaust gas such as kiln 2 may be added to dilute the oxygen concentration.

The temperature control in the bowl-shaped mixing tank 3 may be performed as follows, for example. That is, a thermometer for measuring the temperature of the mixture C is installed in the vertical mixing tank 3 and an oxygen analyzer for detecting the oxygen concentration in the exhaust gas from the vertical mixing tank 3 is installed. Then, the flow rate of the oxygen-containing gas G and / or the range in which O ₂ is not detected in the exhaust gas from the vertical mixing tank 3 so that the temperature of the mixture C measured with the thermometer is within the target temperature ± allowable range. The oxygen concentration may be adjusted.

[Hot forming process]
The mixture C composed of the powdered carbon material A and the powdered iron ore B is pressure-molded using a molding facility (for example, a twin-roll molding machine for hot forming) 4 to form an agglomerate D. In order to prevent or suppress the temperature drop of the mixture C at the time of molding, for example, the molding machine 4 has a sealed structure, and the molding process is performed while circulating the oxygen-containing gas G similar to that described in the mixing step. In this way, in the mixing step and the hot forming step, by performing the treatment while circulating the oxygen-containing gas G, the temperature of the mixture C is maintained at a predetermined temperature at the time of forming, and the carbonaceous material is softened and melted (flow state) ), A dense agglomerate D can be obtained with a relatively small pressure.

  The agglomerated material D thus formed enters the voids of the powdered iron ore B with the molten carbon material A having a softening and melting property, and the carbon material A acts as a lubricant to agglomerate. Since the molding pressure applied to the surface of the agglomerated material D extends almost uniformly to the inside of the agglomerated material D, only the vicinity of the surface is prevented from being consolidated, and the porosity distribution in the agglomerated material D is averaged. Thus, an agglomerate D that does not explode when heated 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. D has high strength and excellent reducibility.

[Heat treatment process]
The agglomerate D is charged into a heat treatment facility (for example, a shaft furnace) 5 adjusted to a temperature equal to or higher than the hot forming temperature to remove volatile matter and tar content remaining in the agglomerate D, and carbonaceous material Solidify. In order to raise the temperature in the degassing tank 5 to a temperature equal to or higher than the hot forming temperature, the degassing tank 5 may be heated with a heater, but instead of or in addition to this, the above mixing is performed in the shaft furnace 5. The degassing process is performed while circulating the same oxygen-containing gas G as described in the process.

The temperature and holding time in the shaft furnace 5 may be controlled as follows, for example. That is, a thermometer for measuring the temperature of the agglomerate D is installed in the shaft furnace 5 and a gas analyzer for detecting the oxygen concentration and the hydrocarbon gas concentration in the exhaust gas from the shaft furnace 5 is installed. Then, the flow rate of the oxygen-containing gas G and / or the range in which O ₂ is not detected in the exhaust gas from the shaft furnace 5 so that the temperature of the agglomerate D measured by the thermometer is within the target temperature ± allowable range. The oxygen concentration is adjusted, and the time when the hydrocarbon gas is substantially not detected in the exhaust gas from the shaft furnace 5 may be determined as the end of the holding time.

  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 reason why the lower limit of the temperature in the shaft furnace 5 is set as the molding temperature is that when the molding temperature is below the molding temperature, it is very difficult to remove volatile components and tar components. If the temperature in the shaft furnace 5 is too high, the iron content in the molded product D is unnecessarily reduced in the shaft furnace 5 and the strength of the agglomerate D is lowered. desirable. 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 combusted if discharged into the atmosphere while being hot. It is desirable to discharge from.

  Further, as described above, unburned hydrocarbons remain in the exhaust gas (not shown) from the rotary dryer 1, the vertical mixing tank 3, the molding machine 4, and the shaft furnace 5 that are partially burned by adding oxygen. These exhaust gases are preferably sucked and collected using an unillustrated ejector or the like, and the collected gas is preferably effectively used as heating fuel for the rotary kiln 2 or the like.

  Further, the gas sucked by the ejector may be introduced into a combustion chamber (not shown) separately installed and combusted. Thereby, even when oxygen is excessively supplied to each device such as the rotary dryer, combustion of the carbonaceous material can be suppressed.

  The agglomerated material D after degassing is cooled with an inert gas in the bunker 6, then discharged from the bunker 6, and sieved with a screen 8. The sieving lump E is recovered as the intended high-strength carbonaceous material-incorporated agglomerated material while being recycled.

(Modification)
In the said embodiment, although the example which performs a process in oxygen-containing gas atmosphere in all the processes of a carbonaceous material heating process, a mixing process, a hot forming process, and a heat treatment process was shown, any one or two or three You may process in oxygen-containing gas atmosphere only in one process.

  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 heating step, the mixing step, and the hot forming step, or in any one or two steps, the oxygen-containing gas You may process in atmosphere.

  Moreover, although the example which uses a rotary dryer for a carbonaceous material drying process was shown in the said embodiment, you may use a fluidized bed type dryer and an external heating kiln.

  Moreover, although the example which uses a rotary kiln for a raw material heating process was shown in the said embodiment, you may use a fluidized bed type heating furnace and an external heating kiln.

  Moreover, although the example which uses a bowl-shaped mixing tank for a mixing process was shown in the said embodiment, you may use a paddle type mixer and a screw type mixer.

  Moreover, in the said embodiment, although the example which uses a twin roll type | mold molding machine for the hot forming process was shown, you may use an extrusion molding machine.

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.

Explanation of symbols

1: Charcoal heating equipment (rotary dryer)
2: Ore heating equipment (rotary kiln)
3: Mixing equipment (vertical mixing tank)
4: Molding equipment (twin roll molding 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: Mixture D: Carbonaceous material agglomerate (briquette)
E: Carbonized material agglomerated material (sieve lump)
F: Sieve powder G: Oxygen-containing gas (air)

Claims (2)

A carbonaceous material heating step of heating a powdered carbonaceous material having softening and melting properties at 350 ° C. or less;
A raw material heating step of heating the powdered iron-containing raw material to 400 to 800 ° C;
A mixing step of a mixture of the powdered carbonaceous material after heating and the powdered iron-containing raw material after the heating and mixing 250 to 550 ° C.,
A hot forming step of hot forming the mixture into an agglomerated carbonaceous material agglomerated product,
A method for producing an agglomerated carbonaceous material agglomerated material, wherein the treatment is performed while circulating a gas containing oxygen in at least one of the carbonaceous material heating step, the mixing step, and the hot forming step. A carbonaceous material heating step of heating a powdered carbonaceous material having softening and melting properties at 350 ° C. or less;
A raw material heating step of heating the powdered iron-containing raw material to 400 to 800 ° C;
A mixing step of a mixture of the powdered carbonaceous material after heating and the powdered iron-containing raw material after the heating and mixing 250 to 550 ° C.,
A hot forming step in which the mixture is hot formed into a carbonaceous agglomerate,
A heat treatment step of removing the volatile matter and tar content remaining in the carbonaceous material agglomerated material while maintaining the carbonaceous material agglomerated material at a temperature equal to or higher than the hot molding temperature,
A method for producing an agglomerated carbonaceous material-containing agglomerated product, characterized in that in at least one of the carbonaceous material heating step, the mixing step, the hot forming step, and the heat treatment step, treatment is performed while circulating a gas containing oxygen. .

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