WO2012015067A1 - 焼結用原料の製造方法 - Google Patents
焼結用原料の製造方法 Download PDFInfo
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- WO2012015067A1 WO2012015067A1 PCT/JP2011/067725 JP2011067725W WO2012015067A1 WO 2012015067 A1 WO2012015067 A1 WO 2012015067A1 JP 2011067725 W JP2011067725 W JP 2011067725W WO 2012015067 A1 WO2012015067 A1 WO 2012015067A1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/16—Sintering; Agglomerating
- C22B1/20—Sintering; Agglomerating in sintering machines with movable grates
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/242—Binding; Briquetting ; Granulating with binders
- C22B1/244—Binding; Briquetting ; Granulating with binders organic
- C22B1/245—Binding; Briquetting ; Granulating with binders organic with carbonaceous material for the production of coked agglomerates
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Definitions
- the present invention relates to a method for producing a raw material for sintering, in which granulation is performed using a disk pelletizer and then a blast furnace sintered ore is produced using a downward suction type dweroid-type sintering machine.
- Sinter ore used as a blast furnace raw material is generally manufactured through the following processing method of the sintered raw material. That is, first, an iron ore having a particle size of 10 mm or less, a SiO 2 -containing raw material made of silica, serpentine or nickel slag, a limestone powder raw material containing CaO such as limestone, and a heat source such as powdered coke or anthracite Using a drum mixer, an appropriate amount of water is added and mixed and granulated to form a granulated product called pseudo particles.
- the blended raw material composed of the pseudo particles is charged onto a pallet of a Dwytroid type sintering machine so as to have an appropriate thickness, for example, 500 to 700 mm, and ignites the solid fuel in the surface layer portion.
- the solid fuel is combusted while sucking air toward it, and the sintered raw material blended by the combustion heat is sintered to form a sintered cake.
- the sintered cake is crushed and sized to obtain a sintered ore having a certain particle size or more.
- those having a particle size smaller than that are returned to ore and reused as sintering raw materials.
- the reducibility of the sintered product ore manufactured in this way is a factor that greatly affects the operation of the blast furnace, as pointed out in the past.
- the reducibility of the sinter has a good negative correlation with the fuel ratio through the gas utilization rate in the blast furnace.
- the reducibility of the sinter is improved, the fuel ratio in the blast furnace decreases.
- the cold strength of the manufactured sintered product ore is also an important factor for ensuring the air permeability in the blast furnace, and each blast furnace is operated with a lower limit standard for the cold strength. Therefore, it can be said that the desired sintered ore for the blast furnace is excellent in reducibility and has high cold strength.
- powder iron ore composed of fine iron ore and coarse iron ore, limestone and quicklime are mixed with a mixer, the mixture is granulated by adding water with the first pelletizer, and the granulated pseudo particles are screened.
- HPP Hybrid Pelletized Sinter
- the method for producing a raw material for sintering described in Patent Document 4 uses a disk pelletizer for granulating the raw material for sintering.
- a disk pelletizer for granulating the raw material for sintering.
- an iron ore containing pellet feed that is fine powder is used. Stone can be granulated, and by combining this HPS method and the method for producing sintering raw materials described in Patent Documents 1 to 3, it is possible to granulate iron ore containing fine powder such as pellet feed become.
- Patent Documents 1 to 3 were originally developed for the purpose of expanding the use of pellet feed of fine iron ore (average particle size: 150 ⁇ m or less), which was inexpensive at that time, and improving the quality of sintered ore. .
- the amount used has decreased and the granulation strength in the pelletizer has decreased. Therefore, if the method for producing a raw material for sintering described in Patent Documents 1 to 3 is used as it is, the pseudo particle size is kept small, the air permeability is poor, and uneven firing is likely to occur. It became clear that there was a need for improvement.
- Patent Document 5 Prepare a sintering raw material consisting of iron ore, SiO2 containing raw material, limestone powder raw material and solid fuel powder raw material, The iron ore, SiO2 containing raw material and limestone powder raw material are mixed with a drum mixer for stirring and mixing to produce a mixed raw material, The mixed raw material is granulated with a disk pelletizer to produce granulated particles, Supplying the granulated particles to a drum mixer for outer layer formation; The solid fuel powder material is added to the granulated particles supplied to the outer layer formation drum mixer from the outlet side of the outer layer formation drum mixer, and the outer layer formation drum is added from the addition of the solid fuel powder material.
- a method for producing a raw material for sintering comprising forming a solid fuel-based powder raw material layer on the surface of the granulated particles for 40 seconds or less until discharging from the mixer and for 10 seconds or more.
- Japanese Patent No. 3755452 Japanese Patent No. 3794332 Japanese Patent No. 3656632 Japanese Patent Publication No.2-4658 JP 2011-032577 A
- Patent Document 5 has made it possible to produce a raw material for sintering that can efficiently produce a good raw material even when a disk pelletizer is used for granulation.
- the object of the present invention relates to the improvement of the technique disclosed in the above-mentioned Patent Document 5, and effectively utilizes finely ground coke that has been limited in its use due to uneven burning that occurs in a sintering machine.
- an advantageous production method of a raw material for sintering capable of greatly improving the productivity of sintered ore is provided.
- the present inventors granulated a sintered raw material excluding a solid fuel powder raw material or a limestone powder raw material and a solid fuel powder raw material, and on the surface of the obtained granulated particles (hereinafter referred to as pseudo particles).
- the inventors have intensively studied a technique for improving productivity when performing a so-called exterior treatment in which a solid fuel powder raw material or a limestone powder raw material and a solid fuel powder raw material are adhered.
- high carbon dust such as fine coke generated in CDQ and the like is used in combination with solid fuel-based powder raw materials represented by conventional powder coke and anthracite at an appropriate ratio so as to adhere to pseudo particles.
- the gist configuration of the present invention is as follows. (1) Prepare a sintering raw material comprising iron ore, SiO 2 containing raw material, limestone powder raw material and solid fuel powder raw material, The iron ore, SiO 2 containing raw material and limestone powder raw material are mixed with a drum mixer for stirring and mixing to produce a mixed raw material, The mixed raw material is granulated with a disk pelletizer to produce pseudo particles, Supplying the pseudo particles to an outer layer forming drum mixer; The solid fuel powder raw material layer is formed on the surface of the pseudo particles by adding the solid fuel powder raw material to the pseudo particles supplied to the outer layer forming drum mixer from the discharge port side of the outer layer forming drum mixer. And The solid fuel-based powder raw material contains 5 to 40 mass% of high carbon dust. A method for producing a raw material for sintering.
- the solid fuel-based powder raw material contains 5 to 40 mass% of high carbon dust.
- the high carbon dust is at least one selected from the group consisting of CDQ dust collection powder, dust collection powder during iron powder production, and dust collection powder in a storage tank, and the C concentration is 50 mass% or more.
- (11) The method for producing a sintering raw material according to (1), wherein the solid fuel-based powder raw material has an average particle diameter of 250 ⁇ m to 2.5 mm.
- a method for producing a ligation raw material is adjusted.
- the pseudo particle diameter can be kept large, and since it is not embedded in the pseudo particle, the combustibility is improved. Furthermore, since it is used in combination with ordinary solid fuel, scattering of high carbon dust, which is fine powder, is suppressed and handling becomes easy. In addition, since the exterior of the solid fuel void is filled with high carbon dust, the strength of the exterior increases, and as a result, the strength of the pseudo particles is improved. Powder generation is also reduced. In addition, according to the present invention, since the pseudo particle diameter can be increased, the exterior time on the surface of the pseudo particle can be shortened, and the state of being built can be avoided.
- the present invention when a limestone powder raw material layer is first formed on the surface of the pseudo particles granulated by a disk pelletizer, and then a solid fuel powder raw material layer containing high carbon dust is formed, Since the solid fuel-based powder raw material layer is formed in the outermost layer of the raw material for sintering granulated by the pelletizer, it is possible to reliably prevent the occurrence of uneven burning during sintering.
- the C concentration is 50 mass% or more, it can be used as a coagulating material for sintering. Even if the C concentration is less than 50 mass%, other fine powder having a C concentration of 50 mass% or more can be used. If it is mixed and the C concentration is adjusted to 50 mass% or more, it can be used.
- FIG. 6A is an image view of a cross section of a pseudo particle in which high carbon dust is embedded according to a conventional method
- FIG. 6B is an enlarged view of the surface layer portion
- FIG. 7 (a) is an image view of a cross section of a pseudo particle that is externally coated with powdered limestone and then powdered coke containing high carbon dust according to the present invention
- FIG. 7 (b) is an enlarged view of the surface layer portion.
- FIG. 1 shows a case where a limestone powder raw material is supplied to an agitating and mixing drum mixer together with an iron ore or SiO 2 containing raw material
- FIG. 2 shows a limestone powder raw material fed to an outer layer forming drum mixer after granulation of pseudo particles.
- the solid fuel powder raw material is supplied.
- reference numeral 1 is a drum mixer for stirring and mixing
- 2 is a disk pelletizer
- 3 is a drum mixer for forming an outer layer
- 4 is an endless moving grate-type firing furnace
- 5 is an ignition furnace
- 6 is a solid fuel-based powder raw material.
- 7 is a limestone powder raw material supply device.
- iron ore, SiO 2 -containing raw material, and limestone powder raw material are supplied to the stirring and mixing drum mixer 1 and mixed with the added water to produce a mixed raw material. .
- This mixed raw material is supplied to the disk pelletizer 2 and granulated by the disk pelletizer 2 to generate pseudo particles.
- the generated pseudo particles are supplied to the outer layer forming drum mixer 3.
- an outer layer of powder coke which is a solid fuel-based powder raw material, is formed on the pseudo particles granulated by the disk pelletizer 2.
- the raw material for sintering on which the outer layer is formed by the outer layer forming drum mixer 3 is charged into a downward suction type dwytroid type sintering machine 4.
- the outer layer forming drum mixer 3 is supplied with a solid fuel-based powder raw material such as powder coke from the outlet side, for example.
- a conveyor, a spray nozzle or the like is suitable as the powder coke supply device 6,
- the powder is baked while being sucked from below with a blower and transporting the sintering raw material with a conveyor.
- the sintered sintering raw material becomes a sintered cake.
- the sintered cake is crushed and sized, for example, a sintered ore having a particle size of 4 mm or more is supplied to a blast furnace, and the rest is returned to the iron ore. Reuse as a raw material for sintering equivalent to stone. Therefore, the iron ore in the sintering raw material described in the present invention includes returning ore.
- the iron ore and the SiO 2 -containing raw material are supplied to the stirring and mixing drum mixer 1, and are stirred and mixed together with the added water to produce a mixed raw material.
- This mixed raw material is supplied to the disk pelletizer 2 and granulated by the disk pelletizer 2 to generate pseudo particles.
- the generated pseudo particles are supplied to the outer layer forming drum mixer 3.
- the limestone powder raw material is supplied to the pseudo particles granulated by the disk pelletizer 2 on the inlet side of the drum mixer 3 to form a limestone base layer, and then the drum mixer 3 Powder coke, which is a solid fuel-based powder raw material, is supplied on the discharge port side to form an outer layer of coke on the limestone foundation layer.
- the raw material for sintering on which the outer layer is formed is charged into the downward suction type Dwytroid type sintering machine 4 and fired, as in the case of FIG.
- the average particle diameter of the solid fuel-based powder raw material 5 used for the exterior treatment has been about 250 ⁇ m to 2.0 mm.
- the average particle size of the solid fuel-based powder raw material that has been conventionally used is relatively large, and it is not always possible to form a strong outer shell layer of the solid fuel-based powder raw material.
- the speed a sufficiently satisfactory speed was not obtained.
- FIG. 3 shows the results of examining the relationship between the particle size of the powder coke and the combustion zone moving speed (hereinafter simply referred to as the combustion speed).
- the combustion speed As shown in the figure, the smaller the particle size of the powder coke, the greater the specific surface area of the powder coke and the higher the ambient temperature, so the combustion rate increases. Therefore, an improvement in the combustion rate can be expected by using such ultrafine powder and highly reactive carbon material (high carbon dust) in an appropriate ratio.
- the results of examining the influence on the burning rate and the maximum temperature reached in the layer of the pseudo particles coated with the powdered coke combined with the high carbon dust are shown. Shown in relation to rate.
- the high carbon dust fine powder having a sieve size of 50 ⁇ m was used. Further, the total coke amount in the pseudo particles was fixed at 5 mass%.
- the mixing ratio of high carbon dust is 0.25 mass% or more, that is, the mixing ratio of high carbon dust out of all carbon (solid fuel powder raw material).
- the ratio is 5 mass% or more, the combustion rate increases, and the maximum reachable temperature in the layer increases accordingly.
- the blending ratio of the high carbon dust exceeds 2 mass% (combination ratio with respect to the powder coke: 40 mass%), the highest temperature reached in the layer starts to decrease.
- the blending ratio (combination ratio) of the high carbon dust in the solid fuel powder raw material is limited to a range of 5 to 40 mass%. This is because, in the solid fuel-based powder raw material, if the blending ratio of the high carbon dust is less than 5 mass%, it cannot be said that the improvement of the combustibility and the granulation strength is sufficient. This is because the flammability decreases and the combustibility deteriorates.
- FIG. 5 shows the results of examining the granulated strength of the pseudo particles when the powder coke combined with the high carbon dust is used and the sintering strength when the sintering is performed thereafter.
- FIG. 5 also shows the results of examining the granulation strength and the sintering strength of the pseudo particles when high carbon dust is housed inside the pseudo particles.
- the granulation strength and sintering strength were estimated based on the following estimation formulas (Equation 1 and Equation 2).
- ⁇ strength of pseudo particles (N), ⁇ : degree of liquid fullness ( ⁇ ), S: powder surface area (m 2 ), ⁇ : porosity of pseudo particles ( ⁇ ), ⁇ : surface of water Tension (N / m), ⁇ : contact angle with water (°), d: pseudo particle size (m)
- ⁇ t tensile strength (MPa)
- ⁇ 0 substrate strength (MPa)
- P porosity ( ⁇ )
- c constant ( ⁇ )
- the granulation strength of the pseudo particles was remarkably improved.
- the reason for this is considered to be that wettability is greatly improved by covering the hydrophobic carbonaceous material.
- the sintering strength of the pseudo particles is also greatly improved. This reason is considered to be caused by a decrease in the porosity. That is, according to the present invention, when an appropriate amount of high carbon dust is used in combination, fine high carbon dust penetrates into the voids of ordinary powder coke, and as a result, generation of voids (destructive origin) generated after carbon firing is suppressed. This is thought to be due to this.
- FIG. 6 (a) and FIG. 7 (a) show, according to the conventional method, pseudo particles with ultra fine powder / high reactivity carbon material (high carbon dust) and super fine powder / high reactivity carbon material (high The image of the cross section of the pseudo particle which coat
- the granulation strength and the sintering strength can be improved, the combustion rate can be increased, and the outer granulation time can be shortened. As a result, the productivity is remarkably improved.
- An improvement is achieved. That is, by adding high carbon dust, the wettability is greatly improved by covering the hydrophobic carbonaceous material, resulting in a marked improvement in granulation strength. As a result of the intrusion of high carbon dust, the generation of voids (breaking origin) that occurs after carbon firing is suppressed, and the sintering strength of the pseudo particles is greatly improved. Thus, it can be reduced to about 1 ⁇ 2.
- the high carbon dust preferably has a size of 50 ⁇ m or less and a C concentration of 50 mass% or more. This is because when the size of the high carbon dust exceeds 50 ⁇ m, the powder coke is not closely packed with the powdered coke, and the coverage on the particle surface tends to decrease. In addition, the suitable minimum of the magnitude
- the size of the high carbon dust is defined as a circle-equivalent diameter when the high carbon dust is spherical, and as a sieve diameter when the high carbon dust is non-spherical.
- the high carbon dust is at least one selected from the group consisting of CDQ dust collection powder, dust collection powder during iron powder production, and dust collection powder in a storage tank, and the C concentration is adjusted to 50 mass% or more. It is preferable that Table 1 shows examples of components of CDQ dust collection powder, dust collection powder during iron powder production, and dust collection powder in the storage tank.
- a transport device for example, a belt conveyor, a screw conveyor, etc.
- a belt conveyor increases the failure frequency of the motor and roller that supply driving force to the belt.
- the screw conveyor does not require a large number of rollers and has a simple structure. Therefore, even if it is inserted into the drum mixer for forming the outer layer, the screw conveyor is unlikely to break down and can operate stably. If the screw conveyor is inserted into the drum mixer for forming the outer layer, it is possible to adjust the tip position and add the solid fuel powder raw material or limestone powder raw material to a predetermined position. In that case, since the impact is relaxed (only the impact of natural fall), the collapse of the pseudo particles can be prevented. In addition, the collapse of the solid fuel-based powder raw material and the limestone-based powder raw material can be prevented, and the previously adjusted particle size can be maintained. Accordingly, it is preferable to use a screw conveyor as the conveying means.
- the average particle diameter of the limestone powder raw material 4 used for the exterior treatment is preferably 250 ⁇ m to 5.0 mm, and the average particle diameter of the solid fuel powder raw material 5 is preferably 250 ⁇ m to 2.5 mm.
- the average particle diameter of the limestone powder raw material 4 exceeds 5.0 mm and the average particle diameter of the solid fuel powder raw material 5 exceeds 2.5 mm, the coarse particles of the limestone powder raw material 4 and the solid fuel powder raw material 5 Therefore, it becomes difficult to uniformly coat the surface of the pseudo particle in a short time.
- the average particle size is less than 250 ⁇ m, the fine particles of the solid fuel-based powder raw material and the limestone-based powder raw material increase, intrude through the gaps that inevitably exist in the pseudo particles, and enter the solid fuel-based powder raw material also inside It becomes a raw material for sintering mixed with limestone powder raw material.
- the blending ratios of the solid fuel powder raw material and the limestone powder raw material with respect to the entire sintering raw material are respectively 3.0 to 6.0 mass% for the solid fuel powder raw material and 6.0 to 12% for the limestone powder raw material. It is preferable to set it to about 0 mass%. More preferably, they are in the range of solid fuel powder raw material: 3.5 to 5.0 mass%, limestone powder raw material: 6.5 to 10.0 mass%.
- the exterior time is preferably about 10 to 50 seconds. More preferably, it is in the range of 10 to 40 seconds, and further preferably in the range of 15 to 30 seconds.
- FIG. 8 shows the results of examining the preferred exterior granulation time of pseudo particles coated with powdered coke combined with high carbon dust according to the present invention and pseudo particles coated with ordinary powdered coke according to the conventional method. Shown in relation to productivity.
- the blending ratio of the high carbon dust to the powder coke was 10 mass%.
- the preferred exterior granulation time of conventional pseudo particles was around 40 seconds, whereas the preferred exterior granulation time of pseudo particles according to the present invention was about 20 to 25 seconds.
- the grain time could be greatly shortened.
- the productivity of the outer layer forming drum mixer can be improved.
- a CF melt can be selectively generated on the surface of the raw material for sintering, and a sintered ore can be produced efficiently.
- Example 1 As shown in FIG. 2, the iron ore and the SiO 2 -containing raw material were charged into the stirring and mixing drum mixer 1 from the charging inlet to generate a mixed raw material.
- SiO 2 -containing raw material silica stone or nickel slag was used.
- the mixed raw material was charged into the disk pelletizer 2 and granulated in the disk pelletizer 2 to obtain pseudo particles.
- the obtained pseudo particles are charged into the outer layer forming drum mixer 3, and the residence time until the pseudo particles reach the outlet of the outer layer forming drum mixer 3 is 40 seconds.
- the average particle size: 1.2 mm limestone as a raw material: 10 mass% is added, and the residence time until reaching the discharge port of the drum mixer 3 for outer layer formation is 20 seconds.
- Particle size 0.9 mm powder coke: 4 mass% and average particle size: 50 ⁇ m high carbon dust: 1 mass% (combination ratio to all cokes: 20%) were added. Further, the specific addition was performed by adjusting the tip position of a screw conveyor arranged so as to be able to advance and retreat in the longitudinal direction in the outer layer forming drum mixer 3 from the loading inlet or the outlet. Accordingly, the exterior time is 40 seconds (limestone powder raw material) and 20 seconds (solid fuel powder raw material). This is an invention example.
- Comparative Example 1 iron ore and SiO 2 -containing raw material were charged into the stirring and mixing drum mixer 1 from the charging inlet to produce a mixed raw material, and then charged into the disk pelletizer 2 and granulated. Thus, pseudo particles were obtained. Next, the obtained pseudo particles are charged into the outer layer forming drum mixer 3, and the average particle size is at a position where the residence time until the pseudo particles reach the outlet of the outer layer forming drum mixer 3 is 80 seconds. : 1.2 mm limestone: 10 mass% is added, and the residence time until reaching the outlet of the outer layer forming drum mixer 3 is 50 seconds. 9 mm powder coke: 5 mass% was added.
- Comparative Example 2 a raw material for sintering was produced under the same conditions as Comparative Example 1, except that the exterior time was 40 seconds (limestone powder raw material) and 20 seconds (solid fuel powder raw material).
- Sintering raw materials for the inventive examples and comparative examples 1 and 2 were sintered. As a result, a sintered ore having sufficient strength was obtained with the sintering raw materials of the inventive example and comparative example 1. This indicates that the CF melt was generated on the surface of the raw material for sintering.
- the exterior time can be shortened, and further, the sintered raw material having sufficient strength can be obtained by sintering the raw material for sintering.
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Abstract
Description
即ち、まず粒径が10mm以下の鉄鉱石、及び珪石、蛇紋岩又はニッケルスラグなどからなるSiO2含有原料、及び石灰石などのCaOを含有する石灰石系粉原料、及び粉コークス又は無煙炭などの熱源となる固体燃料系粉原料を、ドラムミキサーを用いて、これに適当量の水分を添加して混合、造粒して擬似粒子と呼ばれる造粒物を形成する。この擬似粒子からなる配合原料は、ドワイトロイド式焼結機のパレット上に適当な厚さ、例えば500~700mmになるように装入して表層部の固体燃料に着火し、着火後は下方に向けて空気を吸引しながら固体燃料を燃焼させ、その燃焼熱によって配合した焼結原料を焼結させて焼結ケーキとする。この焼結ケーキは、破砕、整粒され、一定の粒径以上の焼結鉱を得る。一方、それ未満の粒径のものは返鉱となり、焼結原料として再利用される。
「 鉄鉱石、SiO2含有原料、石灰石系粉原料及び固体燃料系粉原料からなる焼結原料を準備し、
前記鉄鉱石、SiO2含有原料と石灰石系粉原料を撹拌混合用ドラムミキサーで混合して、混合原料を生成し、
前記混合原料をディスクペレタイザーで造粒し、造粒粒子を生成し、
前記造粒粒子を外層形成用ドラムミキサーに供給し、
前記外層形成用ドラムミキサーに供給された造粒粒子に、前記外層形成用ドラムミキサーの排出口側から、前記固体燃料系粉原料を添加し、前記固体燃料系粉原料の添加から外層形成用ドラムミキサーからの排出までの40秒以下で10秒以上の外装時間の間に前記造粒粒子の表面に固体燃料系粉原料層を形成する
ことを特徴とする焼結用原料の製造方法。」
その結果、CDQなどで発生する微粉コークスなどの高カーボンダストを、適正な割合で、従来の粉コークス、無煙炭などに代表される固体燃料系粉原料と共に併用して、擬似粒子に付着させるようにすれば、燃焼性および造粒強度が大幅に向上し、その結果、焼結用原料の生産性が向上するとの知見を得た。
なお、本発明によれば、上記したCDQなどで発生する微粉コークスのほか、C濃度が50mass%以上の微粉も使用可能であることが究明されたので、これらを総称して高カーボンダストと称する。
本発明は、これらの知見に基づいてなされたものである。
(1)鉄鉱石、SiO2含有原料、石灰石系粉原料及び固体燃料系粉原料からなる焼結原料を準備し、
前記鉄鉱石、SiO2含有原料及び石灰石系粉原料を撹拌混合用ドラムミキサーで混合して、混合原料を生成し、
前記混合原料をディスクペレタイザーで造粒して、擬似粒子を生成し、
前記擬似粒子を外層形成用ドラムミキサーに供給し、
前記外層形成用ドラムミキサーに供給された擬似粒子に、前記外層形成用ドラムミキサーの排出口側から、前記固体燃料系粉原料を添加して前記擬似粒子の表面に固体燃料系粉原料層を形成し、
前記固体燃料系粉原料は、高カーボンダストを5~40mass%含有する、
焼結用原料の製造方法。
前記鉄鉱石及びSiO2含有原料を撹拌混合用ドラムミキサーで混合して、混合原料を生成し、
前記混合原料をディスクペレタイザーで造粒して、擬似粒子を生成し、
前記擬似粒子を外層形成用ドラムミキサーに供給し、
前記外層形成用ドラムミキサーに供給された擬似粒子に、前記外層形成用ドラムミキサーの装入口側から前記石灰石系粉原料を添加すると共に、前記外層形成用ドラムミキサーの排出口側から前記固体燃料系粉原料を添加して、前記擬似粒子の表面に石灰石系粉原料層及び固体燃料系粉原料層を形成し、
前記固体燃料系粉原料は、高カーボンダストを5~40mass%含有する、
焼結用原料の製造方法。
(4)前記高カーボンダストは、50μm以下の大きさで、かつ、50mass%以上のC濃度を有する(1)または(2)に記載の焼結用原料の製造方法。
(7)前記滞留時間が20~40秒である(6)に記載の焼結用原料の製造方法。
(8)前記固体燃料系粉原料および石灰石系粉原料の添加が、その添加から前記ドラムミキサーからの排出に至る滞留時間が10~50秒となるように行われる(2)に記載の焼結用原料の製造方法。
(9)前記滞留時間が20~40秒である(8)に記載の焼結用原料の製造方法。
(11)前記固体燃料系粉原料が、250μm~2.5mmの平均粒径を有する(1)に記載の焼結用原料の製造方法。
(12)前記固体燃料系粉原料が、250μm~2.5mmの平均粒径を有し、前記石灰石系粉原料が、250μm~5.0mmの平均粒径を有する、(2)に記載の焼結用原料の製造方法。
また、本発明によれば、擬似粒子径を大きくできるため、擬似粒子表面への外装時間も短くでき、内装化される状態を避けることができる。
さらに、本発明に従い、ディスクペレタイザーで造粒された擬似粒子の表面に、まず石灰石系粉原料層を形成し、その後、高カーボンダストを含む固体燃料系粉原料層を形成した場合には、ディスクペレタイザーによって造粒された焼結用原料の最外層に固体燃料系粉原料層が形成されていることになるので、焼結時のムラ焼け発生を確実に阻止することができる。
加えて、燃料としては、C濃度が50mass%以上であれば焼結用凝結材として使用可能であり、またC濃度が50mass%未満であっても、他のC濃度が50mass%以上の微粉と混合してC濃度を50mass%以上に調整してやれば、使用が可能となる。
図1,2に、本発明に従う、焼結用原料の好適製造工程を模式で示す。図1は、石灰石系粉原料を、鉄鉱石やSiO2含有原料と共に撹拌混合用ドラムミキサーに供給する場合、また図2は、擬似粒子を造粒後に、外層形成用ドラムミキサーに石灰石系粉原料ついで固体燃料系粉原料を供給する場合である。
図1,2において、符号1は撹拌混合用ドラムミキサー、2はディスクペレタイザー、3は外層形成用ドラムミキサー、4は無端移動グレート式焼成炉、5は点火炉、そして6が固体燃料系粉原料の供給装置、7が石灰石系粉原料の供給装置である。
この混合原料は、ディスクペレタイザー2に供給され、このディスクペレタイザー2で造粒し、擬似粒子を生成する。生成された擬似粒子は、外層形成用ドラムミキサー3に供給される。
外層形成用ドラムミキサー3では、ディスクペレタイザー2で造粒された擬似粒子に対し、固体燃料系粉原料である粉コークスの外層を形成する。
この外層形成用ドラムミキサー3で外層が形成された焼結用原料は、下方吸引式のドワイトロイド式焼結機4に装入される。このドワイトロイド式焼結機4では、点火炉5で焼結用原料の粉コークスに添加されて、焼成が行われる。
ここで、外層形成用ドラムミキサー3には、例えば排出口側から粉コークスなどの固体燃料系粉原料を供給する。かかる粉コークスの供給装置6としては、コンベヤや噴射ノズルなどが好適である。
この混合原料は、ディスクペレタイザー2に供給され、このディスクペレタイザー2で造粒し、擬似粒子を生成する。生成された擬似粒子は、外層形成用ドラムミキサー3に供給される。
外層形成用ドラムミキサー3では、ディスクペレタイザー2で造粒された擬似粒子に対し、ドラムミキサー3の装入口側で石灰石系粉原料を供給して石灰石の下地層を形成し、ついでドラムミキサー3の排出口側で固体燃料系粉原料である粉コークスを供給して石灰石の下地層の上にコークスの外層を形成する。
その後、外層が形成された焼結用原料を、下方吸引式のドワイトロイド式焼結機4に装入して焼成が行われるのは、図1の場合と同じである。
このように、従来使用されてきた固体燃料系粉原料の平均粒径は比較的大きかったこともあって、必ずしも強固な固体燃料系粉原料の外殻層を形成することができず、また燃焼速度についても十分に満足のいく速度は得られなかった。
同図に示したとおり、粉コークスの粒径が小さくなればなるほど、粉コークスの比表面積は増大し、また雰囲気温度も高温になるため、燃焼速度は上昇する。
従って、かような超微粉・高反応性炭材(高カーボンダスト)を適正な割合で併用することにより、燃焼速度の向上が期待できるわけである。
同図に示したとおり、高カーボンダストを外装した本発明に従う擬似粒子では、高カーボンダストの配合率が0.25mass%以上、すなわち全カーボン(固体燃料系粉原料)のうち高カーボンダストの配合割合が5mass%以上になると燃焼速度は上昇し、それに伴って層内最高到達温度も上昇する。しかしながら、高カーボンダストの配合割合が2mass%(粉コークスに対する併用割合:40mass%)を超えると、層内最高到達温度は低下し始める。
なお、図5には、比較のため、高カーボンダストを擬似粒子の内部に内装した場合の擬似粒子の造粒強度および焼結強度について調べた結果も併せて示す。
また、造粒強度および焼結強度はそれぞれ、以下に示す推定式(数1、数2)に基づいて推定した。
また、本発明に従った場合には、擬似粒子の焼結強度も格段に向上したが、この理由は、空隙率の低下に起因するものと考えられる。すなわち、本発明に従い、高カーボンダストを適量併用した場合には、通常の粉コークスの空隙に、微細な高カーボンダストが侵入し、その結果、カーボン焼成後に生じる空隙(破壊起点)の生成が抑制されたことによるものと考えられる。
図6(b)と図7(b)を比較すれば明らかなように、従来法に従う擬似粒子では、高カーボンダストが内部に点在しているのに対し、本発明に従う擬似粒子では、高カーボンダストが擬似粒子の外層で粉コークスの間隙に侵入する形で存在している。
すなわち、高カーボンダストの添加により、疎水性の炭材が外装されることによって、濡れ性が大きく改善される結果、造粒強度が格段に向上し、また通常の粉コークスの空隙に、微細な高カーボンダストが侵入する結果、カーボン焼成後に生じる空隙(破壊起点)の生成が抑制されて、擬似粒子の焼結強度が格段に向上し、その結果、擬似粒子の外装造粒時間を従来に比べて約1/2程度まで短縮することができるのである。
一方、高カーボンダストのC濃度が50mass%に満たないと燃焼熱が小さく、さらに共存するスラグ成分・灰分により、粉コークスの燃焼性が阻害されるという不利が生じる。
ここに、高カーボンダストの大きさとは、高カーボンダストが球状の場合には円相当径、一方非球形の場合には、篩い目径と定義する。
前記高カーボンダストとしては、CDQ集塵粉、鉄粉製造時の集塵粉および貯骸槽の集塵粉からなるグループから選択された少なくとも一つであり、C濃度が50mass%以上に調整されたものであるのが好ましい。CDQ集塵粉、鉄粉製造時の集塵粉および貯骸槽の集塵粉の成分例を表1に示す。
なお、焼結用原料全体に対する固体燃料系粉原料および石灰石系粉原料の配合割合はそれぞれ、固体燃料系粉原料:3.0~6.0mass%、石灰石系粉原料:6.0~12.0mass%程度とすることが好ましい。さらに好ましくは固体燃料系粉原料:3.5~5.0mass%、石灰石系粉原料:6.5~10.0mass%の範囲である。
同図に示したとおり、従来の擬似粒子の好適外装造粒時間が40秒前後であったのに対し、本発明に従う擬似粒子の好適外装造粒時間は20~25秒程度とあり、外装造粒時間を大幅に短縮することができた。
このようにして外装処理における外装時間を短縮することによって、外層形成用ドラムミキサーの生産性を向上することができる。しかも、得られた焼結用原料を焼結すると、CF融液を焼結用原料の表面に選択的に生成させて、焼結鉱を効率良く製造することもできる。
図2に示したように、鉄鉱石およびSiO2含有原料を装入口から撹拌混合用ドラムミキサー1に装入して、混合原料を生成した。なお、SiO2含有原料としては、珪石あるいはニッケルスラグを使用した。ついで、この混合原料をディスクペレタイザー2に装入し、このディスクペレタイザー2内で造粒して擬似粒子とした。ついで、得られた擬似粒子を外層形成用ドラムミキサー3に装入し、この擬似粒子が外層形成用ドラムミキサー3の排出口に到達するまでの滞留時間が40秒となる位置で、石灰石系粉原料として平均粒径:1.2mmの石灰石:10mass%を添加し、また外層形成用ドラムミキサー3の排出口に到達するまでの滞留時間が20秒となる位置で、固体燃料系粉原料として平均粒径:0.9mmの粉コークス:4mass%と平均粒径:50μmの高カーボンダスト:1mass%(全コークスに対する併用割合:20%)を添加した。また、具体的な添加は、装入口あるいは排出口から外層形成用ドラムミキサー3内の長手方向に進退可能に配置したスクリューコンベアの先端位置を調整して行った。したがって外装時間は40秒(石灰石系粉原料)、20秒(固体燃料系粉原料)である。
これを発明例とする。
2 ディスクペレタイザー
3 外層形成用ドラムミキサー
4 無端移動グレート式焼成炉
5 点火炉
6 固体燃料系粉原料の供給装置
7 石灰石系粉原料の供給装置
Claims (12)
- 鉄鉱石、SiO2含有原料、石灰石系粉原料及び固体燃料系粉原料からなる焼結原料を準備し、
前記鉄鉱石、SiO2含有原料及び石灰石系粉原料を撹拌混合用ドラムミキサーで混合して、混合原料を生成し、
前記混合原料をディスクペレタイザーで造粒して、擬似粒子を生成し、
前記擬似粒子を外層形成用ドラムミキサーに供給し、
前記外層形成用ドラムミキサーに供給された擬似粒子に、前記外層形成用ドラムミキサーの排出口側から、前記固体燃料系粉原料を添加して前記擬似粒子の表面に固体燃料系粉原料層を形成し、
前記固体燃料系粉原料は、高カーボンダストを5~40mass%含有する、
焼結用原料の製造方法。 - 鉄鉱石、SiO2含有原料、石灰石系粉原料及び固体燃料系粉原料からなる焼結原料を準備し、
前記鉄鉱石及びSiO2含有原料を撹拌混合用ドラムミキサーで混合して、混合原料を生成し、
前記混合原料をディスクペレタイザーで造粒して、擬似粒子を生成し、
前記擬似粒子を外層形成用ドラムミキサーに供給し、
前記外層形成用ドラムミキサーに供給された擬似粒子に、前記外層形成用ドラムミキサーの装入口側から前記石灰石系粉原料を添加すると共に、前記外層形成用ドラムミキサーの排出口側から前記固体燃料系粉原料を添加して、前記擬似粒子の表面に石灰石系粉原料層及び固体燃料系粉原料層を形成し、
前記固体燃料系粉原料は、高カーボンダストを5~40mass%含有する、
焼結用原料の製造方法。 - 前記固体燃料系粉原料は、高カーボンダストを10~40mass%含有する請求項1または2に記載の焼結用原料の製造方法。
- 前記高カーボンダストは、50μm以下の大きさで、かつ、50mass%以上のC濃度を有する請求項1または2に記載の焼結用原料の製造方法。
- 前記混合原料には、高カーボンダストを含有しないことを特徴とする請求項1または2に記載の焼結用原料の製造方法。
- 前記固体燃料系粉原料を添加が、その添加から、前記外層形成用ドラムミキサーの排出に至る滞留時間が10~50秒となるように行われる請求項1に記載の焼結用原料の製造方法。
- 前記滞留時間が20~40秒である請求項6に記載の焼結用原料の製造方法。
- 前記固体燃料系粉原料および石灰石系粉原料の添加が、その添加から前記ドラムミキサーからの排出に至る滞留時間が10~50秒となるように行われる請求項2に記載の焼結用原料の製造方法。
- 前記滞留時間が20~40秒である請求項8に記載の焼結用原料の製造方法。
- 前記高カーボンダストが、CDQ集塵粉、鉄粉製造時の集塵粉および貯骸槽の集塵粉からなるグループから選択された少なくとも一つであり、C濃度を50mass%以上に調整されたものである請求項1または2に記載の焼結用原料の製造方法。
- 前記固体燃料系粉原料が、250μm~2.5mmの平均粒径を有する請求項1に記載の焼結用原料の製造方法。
- 前記固体燃料系粉原料が、250μm~2.5mmの平均粒径を有し、
前記石灰石系粉原料が、250μm~5.0mmの平均粒径を有する、
請求項2に記載の焼結用原料の製造方法。
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JP2013036051A (ja) | 2013-02-21 |
CN103038368B (zh) | 2014-10-15 |
JP5821362B2 (ja) | 2015-11-24 |
CN103038368A (zh) | 2013-04-10 |
BR112013002336B1 (pt) | 2019-01-02 |
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