JP6414903B2 - Production method of carbon interior ore - Google Patents
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- 229910052799 carbon Inorganic materials 0.000 title claims description 134
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims description 130
- 238000004519 manufacturing process Methods 0.000 title claims description 28
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 118
- 239000008188 pellet Substances 0.000 claims description 68
- 229910052742 iron Inorganic materials 0.000 claims description 57
- 238000010438 heat treatment Methods 0.000 claims description 51
- 239000002994 raw material Substances 0.000 claims description 44
- 239000000571 coke Substances 0.000 claims description 40
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 33
- 239000000126 substance Substances 0.000 claims description 27
- 239000013078 crystal Substances 0.000 claims description 24
- 238000001764 infiltration Methods 0.000 claims description 20
- 230000008595 infiltration Effects 0.000 claims description 20
- 239000011230 binding agent Substances 0.000 claims description 13
- 239000000203 mixture Substances 0.000 claims description 12
- 239000007789 gas Substances 0.000 description 86
- 230000009467 reduction Effects 0.000 description 44
- 229910052739 hydrogen Inorganic materials 0.000 description 38
- 230000018044 dehydration Effects 0.000 description 36
- 238000006297 dehydration reaction Methods 0.000 description 36
- 239000011148 porous material Substances 0.000 description 32
- 238000000034 method Methods 0.000 description 23
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 22
- 239000003575 carbonaceous material Substances 0.000 description 22
- 238000012545 processing Methods 0.000 description 18
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 12
- 229910002091 carbon monoxide Inorganic materials 0.000 description 11
- 238000002474 experimental method Methods 0.000 description 11
- 239000002245 particle Substances 0.000 description 9
- 238000000197 pyrolysis Methods 0.000 description 9
- 230000009257 reactivity Effects 0.000 description 9
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 8
- 239000001257 hydrogen Substances 0.000 description 8
- 150000001875 compounds Chemical class 0.000 description 7
- 238000002425 crystallisation Methods 0.000 description 6
- 230000008025 crystallization Effects 0.000 description 6
- 238000000227 grinding Methods 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- 230000007704 transition Effects 0.000 description 6
- 239000000919 ceramic Substances 0.000 description 5
- 238000005469 granulation Methods 0.000 description 5
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- 239000000243 solution Substances 0.000 description 5
- 239000012494 Quartz wool Substances 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 4
- 239000011259 mixed solution Substances 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 238000001878 scanning electron micrograph Methods 0.000 description 4
- 238000005979 thermal decomposition reaction Methods 0.000 description 4
- 150000001721 carbon Chemical class 0.000 description 3
- 239000004568 cement Substances 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 239000003638 chemical reducing agent Substances 0.000 description 3
- 238000000151 deposition Methods 0.000 description 3
- 239000008187 granular material Substances 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 238000007670 refining Methods 0.000 description 3
- 238000005211 surface analysis Methods 0.000 description 3
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- 238000001069 Raman spectroscopy Methods 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000002737 fuel gas Substances 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000012256 powdered iron Substances 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 239000011398 Portland cement Substances 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- MAQAUGBCWORAAB-UHFFFAOYSA-N [C+4].[O-2].[Fe+2].[O-2].[O-2] Chemical compound [C+4].[O-2].[Fe+2].[O-2].[O-2] MAQAUGBCWORAAB-UHFFFAOYSA-N 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000011400 blast furnace cement Substances 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 229910002090 carbon oxide Inorganic materials 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000000701 coagulant Substances 0.000 description 1
- 239000011362 coarse particle Substances 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
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- 230000000694 effects Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 229910052602 gypsum Inorganic materials 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 229910052595 hematite Inorganic materials 0.000 description 1
- 239000011019 hematite Substances 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 230000002209 hydrophobic effect Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 239000003643 water by type Substances 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
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- Manufacture And Refinement Of Metals (AREA)
Description
本発明は、主に高炉原料として用いられる炭素内装鉱（鉱石の細孔内に炭素物質を析出させた塊成鉱）の製造方法に関する。 The present invention relates to a method for producing a carbon interior ore (an agglomerate in which a carbon material is deposited in the pores of an ore) mainly used as a blast furnace raw material.
一般の高炉製鉄法では、原料である鉄鉱石（焼結鉱、塊鉱石など）とコークスが炉頂部から交互に装入され、炉下部の羽口から熱風が吹き込まれる。炉内に装入された鉄鉱石の酸化鉄は、鉄鉱石が炉内を降下する過程で、主にコークスの燃焼で生じた一酸化炭素によって還元されるとともに溶解し、溶銑となって高炉の下部から排出される。高炉製鉄法では、コークスに含まれる炭素は酸化鉄の還元剤として働くものの、炭素と酸化鉄との固体間反応である直接還元ではなく、主に一酸化炭素ガスによる間接還元がなされる。 In a general blast furnace ironmaking method, raw iron ore (sintered ore, lump ore, etc.) and coke are alternately charged from the top of the furnace, and hot air is blown from the tuyeres at the bottom of the furnace. The iron ore iron oxide charged in the furnace is reduced and melted by the carbon monoxide generated mainly by the combustion of coke in the process of the iron ore descending in the furnace. It is discharged from the bottom. In the blast furnace iron making method, carbon contained in coke works as a reducing agent for iron oxide, but is not directly reduced by a solid-solid reaction between carbon and iron oxide, but indirectly reduced mainly by carbon monoxide gas.
また、近年、高炉原料として使用されてきた赤鉄鉱石などの供給量が減少し、結晶水を含むピソライト鉱石やマラマンバ鉱石などの使用量が増加している。これらの結晶水を含む鉄鉱石を焼結鉱製造プロセスの原料として使用すると、鉄鉱石中の結晶水の熱分解に熱が必要なため、熱の供給源である凝結材の使用量が増大する問題がある。また、これらの鉄鉱石を非焼成の塊成鉱とした場合には、酸化鉄の還元に時間がかかりコークス比も高くなる。 In recent years, the supply of hematite ore, which has been used as a blast furnace raw material, has decreased, and the use of pisolite ore and maramamba ore containing crystal water has increased. When iron ore containing these crystal waters is used as a raw material for the sinter production process, heat is required for the thermal decomposition of the crystal water in the iron ore, which increases the amount of coagulant used as the heat source. There's a problem. Moreover, when these iron ores are made into a non-fired agglomerated ore, it takes time to reduce iron oxide, and the coke ratio is also increased.
このような問題に対して、特許文献１には、結晶水を含む鉄鉱石を加熱して脱水する（結晶水を水蒸気として鉄鉱石から離脱させる）ことにより鉄鉱石を多孔質化させた後、木材などの有機物の熱分解ガス（乾留ガス）を接触させ、この熱分解ガスに含まれるタールを鉄鉱石表面に付着させる方法、さらに、このタールが付着した鉄鉱石を５００℃以上に加熱し、タールに含まれる炭素によって鉄鉱石中の酸化鉄を還元する方法が示されている。
また、特許文献２には、結晶水を含む鉄鉱石を加熱して脱水した後、特定の炭材を混合し、この混合物を塊成化して製鉄用の塊成物を製造する方法が示されている。
For such a problem, Patent Document 1 discloses that iron ore containing crystallization water is heated and dehydrated (the crystallization water is separated from the iron ore as water vapor) to make the iron ore porous. A method in which pyrolysis gas (dry distillation gas) of organic matter such as wood is brought into contact and the tar contained in the pyrolysis gas adheres to the surface of the iron ore, and further, the iron ore to which the tar adheres is heated to 500 ° C. or more, A method of reducing iron oxide in iron ore with carbon contained in tar is shown.
Patent Document 2 discloses a method for producing an agglomerate for iron making by heating iron ore containing crystal water and dehydrating it, then mixing a specific carbonaceous material, and agglomerating the mixture. ing.
特許文献１に記載の方法は、鉄鉱石の脱水により生成した細孔内に熱分解ガス中のタールを炭素物質として析出させ、この炭素物質により鉄鉱石中の酸化鉄が還元されるようにしたものであるが、本発明者らの検討によれば、細孔内への炭素析出量が少なく、高い還元反応性が得られない。また、多孔質化した鉄鉱石は圧潰強度が低下しやすいが、特許文献１に記載の方法では、鉄鉱石の圧潰強度の確保については全く考慮されていない。また、特許文献１には、上記の方法で処理した鉄鉱石を原料としてペレットを製造することが示されているが、そのようなペレットも圧潰強度が十分でないことは容易に推測できる。 In the method described in Patent Document 1, tar in the pyrolysis gas is precipitated as a carbon substance in pores generated by dehydration of iron ore, and iron oxide in the iron ore is reduced by this carbon substance. However, according to the study by the present inventors, the amount of carbon deposited in the pores is small, and high reduction reactivity cannot be obtained. Moreover, although the crushing strength of the porous iron ore tends to decrease, the method described in Patent Document 1 does not take into account the securing of the crushing strength of the iron ore at all. Moreover, although it is shown by patent document 1 that a pellet is manufactured from the iron ore processed by said method as a raw material, it can be estimated easily that such a pellet is not enough in crushing strength.
一方、特許文献２に記載の方法は、鉄鉱石の脱水により生成した細孔内に軟化溶融させた炭材を充填させるものである。この方法では、鉄鉱石と炭材の混合物を造粒する必要があるが、鉄鉱石と炭材は性質が異なるため、通常の方法で造粒することは困難である。すなわち、鉄鉱石は一般に親水性であるのに対して炭材は疎水性であり、このため適正に造粒するには、バインダー量を増やしたり、圧縮して造粒するなどの対策が必要であり、特別なコストが必要となる。また、特許文献２には、炭材が鉄鉱石どうしの接着力を高めるために、塊成物の強度が高められるとの記載があるが、強度を評価した実施例の記載はなく、その程度は不明である。 On the other hand, the method described in Patent Document 2 is a method of filling softened and melted carbonaceous material into pores generated by dehydration of iron ore. In this method, it is necessary to granulate a mixture of iron ore and carbonaceous material, but since iron ore and carbonaceous material have different properties, it is difficult to granulate by a normal method. In other words, iron ore is generally hydrophilic, while carbonaceous materials are hydrophobic. Therefore, measures such as increasing the amount of binder or compressing and granulating are necessary for proper granulation. There is a special cost. Further, Patent Document 2 describes that the strength of the agglomerate is increased in order for the carbonaceous material to increase the adhesive strength between the iron ores, but there is no description of examples in which the strength was evaluated, and to that extent Is unknown.
したがって本発明の目的は、以上のような従来技術の課題を解決し、高い還元反応性と圧潰強度を有するとともに、良好な還元粉化性を有する炭素内装鉱（塊成鉱）を低コストに製造することができる炭素内装鉱の製造方法を提供することにある。 Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, and to reduce the cost of carbon interior ore (agglomerated ore) having high reduction reactivity and crushing strength, and also having good reduced powdering properties. It is providing the manufacturing method of the carbon interior ore which can be manufactured.
本発明者らは、上記課題を解決すべく検討を重ねた結果、結晶水を含有する粉鉄鉱石と水硬性バインダーの混合物を造粒して得られたペレットを所定の温度で加熱脱水した後、所定の温度に加熱した状態で高温の粗コークス炉ガスを原料ガスとする化学気相浸透処理を施すことにより、結晶水の脱水により粉鉄鉱石に生成した細孔内に粗コークス炉ガスのガス状タール由来の炭素物質が析出してほぼ完全充填され、これにより高い還元反応性と圧潰強度を有するとともに、良好な還元粉化性を有する炭素内装鉱（塊成鉱）が得られることを見出した。 As a result of repeated investigations to solve the above problems, the present inventors have heated and dehydrated pellets obtained by granulating a mixture of fine iron ore containing crystal water and a hydraulic binder at a predetermined temperature. By applying chemical vapor infiltration treatment using high-temperature crude coke oven gas as a raw material gas in a state heated to a predetermined temperature, the coarse coke oven gas is formed in the pores generated in fine iron ore by dehydration of crystal water. The carbon material derived from the gaseous tar is deposited and almost completely filled, so that a carbon interior ore (agglomerated mineral) having high reduction reactivity and crushing strength and good reduction powdering properties can be obtained. I found it.
本発明は、このような知見に基づきなされたもので、以下を要旨とするものである。
［1］結晶水を含有する粉鉄鉱石と水硬性バインダーの混合物を造粒して得られたペレットを３００〜６００℃に加熱することで脱水した後、該ペレットを３００〜６００℃に加熱した状態で、５００〜１０００℃の粗コークス炉ガスを原料ガスとする化学気相浸透処理を施し、前記結晶水の脱水により粉鉄鉱石に生成した細孔内に粗コークス炉ガスに含まれるガス状タール由来の炭素物質を析出させることを特徴とする炭素内装鉱の製造方法。
［2］上記［1］の製造方法において、結晶水を含有する粉鉄鉱石とバインダーの混合物を造粒して得られたペレットを３２０〜４００℃に加熱することで脱水することを特徴とする炭素内装鉱の製造方法。
The present invention has been made on the basis of such knowledge and has the following gist.
[1] Pellets obtained by granulating a mixture of fine iron ore containing crystal water and a hydraulic binder were dehydrated by heating to 300 to 600 ° C, and then the pellets were heated to 300 to 600 ° C. In the state, the gas phase contained in the crude coke oven gas is subjected to chemical vapor infiltration treatment using a crude coke oven gas at 500 to 1000 ° C. as a raw material gas, and the pores generated in the fine iron ore by dehydration of the crystal water A method for producing a carbon interior ore, characterized by depositing a carbon material derived from tar.
[2] In the production method of [1] above, the pellet obtained by granulating a mixture of fine iron ore containing water of crystallization and a binder is dehydrated by heating to 320 to 400 ° C. Manufacturing method of carbon interior ore.
［3］上記［1］又は［2］の製造方法において、ペレットを３００〜４００℃に加熱した状態で化学気相浸透処理を施すことを特徴とする炭素内装鉱の製造方法。
［4］上記［1］〜［3］のいずれかの製造方法において、ペレットに７００〜１０００℃の粗コークス炉ガスを原料ガスとする化学気相浸透処理を施すことを特徴とする炭素内装鉱の製造方法。
［5］上記［1］〜［4］のいずれかの製造方法において、化学気相浸透処理の処理時間を６０分以上とすることを特徴とする炭素内装鉱の製造方法。
［6］上記［1］〜［5］のいずれかの製造方法において、化学気相浸透処理して得られた炭素内装鉱の炭素含有量が１０mass％−dry以上であることを特徴とする炭素内装鉱の製造方法。
［7］上記［6］の製造方法において、化学気相浸透処理して得られた炭素内装鉱の炭素含有量が１８mass％−dry以上、圧潰強度が１０daＮ以上であることを特徴とする炭素内装鉱の製造方法。
[3] A method for producing a carbon-filled ore according to the method of [1] or [2], wherein the chemical vapor infiltration treatment is performed with the pellets heated to 300 to 400 ° C.
[4] The carbon interior ore characterized in that in the production method according to any one of [1] to [3], the pellet is subjected to chemical vapor infiltration treatment using 700 to 1000 ° C. crude coke oven gas as a raw material gas. Manufacturing method.
[5] The method for producing carbon interior ore according to any one of [1] to [4], wherein the chemical vapor infiltration treatment time is 60 minutes or more.
[6] In the production method according to any one of [1] to [5], the carbon content of the carbon interior ore obtained by chemical vapor infiltration is 10 mass% -dry or more. Manufacturing method for interior ore.
[7] The carbon interior characterized in that the carbon content of the carbon interior ore obtained by the chemical vapor infiltration process is 18 mass% -dry or more and the crushing strength is 10 daN or more. Manufacturing method of ore.
本発明の製造方法によれば、加熱脱水により粉鉄鉱石に生成した細孔内に粗コークス炉ガスのガス状タール由来の炭素物質が析出してほぼ完全充填されるため、高い還元反応性と圧潰強度を有するとともに、良好な還元粉化性を有する炭素内装鉱（塊成鉱）を製造することができる。また、化学気相浸透処理の原料ガスとして粗コークス炉ガスを利用できること、粗コークス炉ガスの顕熱を利用することでペレットを比較的低温で化学気相浸透処理できること、により上記のような優れた性能を有する炭素内装鉱を低コストに製造することができる。 According to the production method of the present invention, the carbon material derived from the gaseous tar of the coarse coke oven gas is deposited and almost completely filled in the pores generated in the fine iron ore by heat dehydration. A carbon interior ore (agglomerated mineral) having a crushing strength and a good reduced powdering property can be produced. In addition, it is possible to use the crude coke oven gas as a raw material gas for the chemical vapor infiltration treatment, and to use the sensible heat of the crude coke oven gas for the chemical vapor infiltration treatment at a relatively low temperature, as described above. Carbon interior ore with high performance can be produced at low cost.
本発明の炭素内装鉱の製造方法は、結晶水を含有する粉鉄鉱石と水硬性バインダーの混合物を造粒して得られたペレットを３００〜６００℃に加熱することで脱水（加熱により粉鉄鉱石が含有する結晶水の少なくとも一部を離脱させる）した後、このペレットを３００〜６００℃に加熱した状態で、５００〜１０００℃の粗コークス炉ガスを原料ガスとする化学気相浸透処理（以下、「ＣＶＩ処理」という）を施し、前記結晶水の脱水により粉鉄鉱石に生成した細孔内に粗コークス炉ガスに含まれるガス状タール由来の炭素物質を析出させるものである。 The method for producing a carbon interior ore according to the present invention comprises dehydration by heating a pellet obtained by granulating a mixture of fine iron ore containing crystal water and a hydraulic binder to 300 to 600 ° C. (At least a part of the crystal water contained in the stone is removed), and then the chemical vapor infiltration treatment using a crude coke oven gas at 500 to 1000 ° C. as a raw material gas in a state where the pellets are heated to 300 to 600 ° C. ( Hereinafter, the carbon material derived from the gaseous tar contained in the crude coke oven gas is deposited in the pores generated in the fine iron ore by dehydration of the crystal water.
本発明で用いるペレットは、結晶水を含有する粉鉄鉱石に水硬性バインダーと水を加えて混合し、造粒機で造粒して得られたものである。
粉鉄鉱石の結晶水の含有量は特に限定されないが、一般的に低品位とされ、安価で取引されていること（経済的側面）、結晶水の加熱脱水に伴い生成する細孔を利用して化学気相浸透処理をすること（技術的側面）などの観点から、特に結晶水の含有量が３mass％以上の粉鉄鉱石が好ましい。そのような鉄鉱石としては、例えば、ピソライト鉱石、マラマンバ鉱石などが挙げられる。
粉鉄鉱石の粒度は特に限定されないが、３ｍｍ以下程度が望ましい。この場合、３ｍｍ程度の粗粒は、造粒の際に核を形成し、その周りに微粉が付着することによりペレットが形成されていく。
The pellet used in the present invention is obtained by adding a hydraulic binder and water to powdered iron ore containing water of crystallization, mixing them, and granulating them with a granulator.
The content of crystal water in fine iron ore is not particularly limited, but it is generally low-grade and traded at low cost (economic aspect), and the pores generated by heating and dehydration of crystal water are used. From the viewpoint of performing chemical vapor infiltration treatment (technical aspect), fine iron ore having a crystal water content of 3 mass% or more is particularly preferable. Examples of such iron ores include pisolite ores and maramamba ores.
Although the particle size of a fine iron ore is not specifically limited, About 3 mm or less is desirable. In this case, coarse particles of about 3 mm form nuclei during granulation, and fine powder adheres around them to form pellets.
水硬性バインダーとしては、例えば、セメント（普通ポルトランドセメント、高炉セメントなど）、高炉スラグ微粉末、石膏などが挙げられ、これらの１種以上を用いることができる。水硬性バインダーの配合量は特に限定されないが、通常、粉鉄鉱石の０．５〜１５mass％、好ましくは３〜１０mass％程度が適当である。
ペレットの造粒方法も特に制限はないが、通常、ディスクペレターザーやドラム型造粒機などで造粒を行う。造粒後のペレットは、通常、水硬性バインダーの水和硬化により所定の強度が得られるまで養生させる。
Examples of the hydraulic binder include cement (ordinary Portland cement, blast furnace cement, etc.), blast furnace slag fine powder, gypsum, and the like, and one or more of these can be used. Although the compounding quantity of a hydraulic binder is not specifically limited, Usually, about 0.5-15 mass% of a powdered iron ore, Preferably about 3-10 mass% is suitable.
There are no particular restrictions on the pellet granulation method, but granulation is usually carried out with a disk pelletizer or a drum granulator. The pellets after granulation are usually cured until a predetermined strength is obtained by hydration hardening of a hydraulic binder.
このようにして得られたペレットを加熱する（以下、「脱水加熱」という場合がある）ことで、粉鉄鉱石が含有する結晶水を脱水する（すなわち、結晶水の少なくとも一部を水蒸気として離脱させる）。ペレットの脱水加熱温度は３００〜６００℃、好ましくは３２０〜４００℃とする。ペレットの脱水加熱温度が３００℃未満、６００℃超のいずれの場合も、結晶水の脱水により生じる細孔がうまく形成できず、ペレットのＢＥＴ比表面積を高めることができない。
ペレットの脱水加熱時間や脱水加熱する雰囲気は特に制限はないが、通常、脱水加熱時間は０．５〜１．５ｈｒ程度、脱水加熱する雰囲気は空気あるいは燃料ガスの燃焼排ガスなどが適当である。
また、ペレットを加熱脱水する方法や設備は特に制限はなく、例えば、ロータリーキルン炉、シャフト炉（竪型炉）、回転炉床炉などのような固気の熱交換が効率的に行える設備（炉）で加熱脱水すればよい。
By heating the pellets obtained in this manner (hereinafter sometimes referred to as “dehydration heating”), the crystal water contained in the fine iron ore is dehydrated (that is, at least part of the crystal water is removed as water vapor). ) The dehydration heating temperature of the pellet is 300 to 600 ° C, preferably 320 to 400 ° C. When the dehydration heating temperature of the pellet is lower than 300 ° C. or higher than 600 ° C., pores generated by dehydration of crystal water cannot be formed well, and the BET specific surface area of the pellet cannot be increased.
The dehydration heating time and the atmosphere for dehydration heating of the pellets are not particularly limited, but usually the dehydration heating time is about 0.5 to 1.5 hr, and the atmosphere for dehydration heating is suitably air or fuel gas combustion exhaust gas.
The method and equipment for heating and dehydrating the pellets are not particularly limited. For example, equipment (furnace) that can efficiently exchange heat of solid gas such as a rotary kiln furnace, shaft furnace (vertical furnace), rotary hearth furnace, etc. ) And heat dehydration.
加熱脱水されたペレットを３００〜６００℃、好ましくは３００〜４００℃に加熱した状態で、５００〜１０００℃、好ましくは７００〜１０００℃の粗コークス炉ガスを原料ガスとする化学気相浸透処理を施す。すなわち、５００〜１０００℃（好ましくは７００〜１０００℃）の粗コークス炉ガスを原料ガスとし、処理温度３００〜６００℃（好ましくは３００〜４００℃）でペレットにＣＶＩ処理を施す。なお、ＣＶＩ処理温度とは、原料ガスを接触させてＣＶＩ処理する際のペレット温度である。
ここで、粗コークス炉ガスとは、コークス炉から排出された後、精製工程を経ないコークス炉ガスのことである。
Chemical vapor infiltration treatment using a crude coke oven gas at 500 to 1000 ° C., preferably 700 to 1000 ° C. as a raw material gas, with the heated and dehydrated pellets heated to 300 to 600 ° C., preferably 300 to 400 ° C. Apply. That is, a crude coke oven gas of 500 to 1000 ° C. (preferably 700 to 1000 ° C.) is used as a raw material gas, and the pellet is subjected to CVI treatment at a treatment temperature of 300 to 600 ° C. (preferably 300 to 400 ° C.). The CVI processing temperature is a pellet temperature when the CVI processing is performed by contacting the raw material gas.
Here, the crude coke oven gas is a coke oven gas that has not been subjected to a refining process after being discharged from the coke oven.
ＣＶＩ処理温度が３００℃未満では、ガス状タール由来の炭素物質の拡散（析出）が遅くなり、細孔内に炭素が十分に浸透しない。また、原料ガス温度が５００℃未満では、ガス状タール由来の炭素物質の分子量分布が大きくなり、細孔内への浸透（析出）が抑制される。一方、ＣＶＩ処理温度が６００℃超では、温度が高いために低沸点のガス状タール由来の炭素物質が十分に析出、固定化されない。なお、粗コークス炉ガスは、コークス炉から１０００℃前後で排出されるので、原料ガス温度は１０００℃程度が上限となる。
ペレットのＣＶＩ処理時間は特に制限はないが、通常、６０ｍｉｎ以上が好ましく、９０ｍｉｎ以上がより好ましく、１８０ｍｉｎ以上が特に好ましい。
ペレットをＣＶＩ処理する方法や設備は特に制限はなく、例えば、脱水加熱処理に用いたような、ロータリーキルン炉、シャフト炉（竪型炉）、回転炉床炉などに原料ガスを流通させればよい。
ＣＶＩ処理の原料ガスとして使用された後の粗ＣＯＧは、通常の精製工程に送られて必要な精製を行った後、燃料ガスなどとして有効利用できる。
When the CVI treatment temperature is less than 300 ° C., the diffusion (precipitation) of the carbon material derived from the gaseous tar is delayed, and the carbon does not sufficiently penetrate into the pores. On the other hand, when the raw material gas temperature is less than 500 ° C., the molecular weight distribution of the carbon material derived from the gaseous tar becomes large, and the penetration (precipitation) into the pores is suppressed. On the other hand, when the CVI treatment temperature exceeds 600 ° C., the carbon material derived from the low-boiling gaseous tar is not sufficiently precipitated and immobilized because the temperature is high. Note that since the crude coke oven gas is discharged from the coke oven at around 1000 ° C., the upper limit of the raw material gas temperature is about 1000 ° C.
The CVI treatment time of the pellet is not particularly limited, but is usually preferably 60 min or more, more preferably 90 min or more, and particularly preferably 180 min or more.
There is no particular limitation on the method and equipment for CVI treatment of pellets, and for example, the raw material gas may be circulated in a rotary kiln furnace, a shaft furnace (a vertical furnace), a rotary hearth furnace, etc. used in the dehydration heat treatment. .
The crude COG after being used as a raw material gas for CVI treatment can be effectively used as a fuel gas or the like after being sent to a normal refining process for necessary refining.
このような本発明法で製造される炭素内装鉱（塊成鉱）は、加熱による結晶水の脱水により粉鉄鉱石に生成した細孔内に粗コークス炉ガスのガス状タール由来の炭素物質が析出してほぼ完全充填されるため、以下のような高い還元反応性と圧潰強度を有するとともに、良好な還元粉化性を有するものとなる。
（1）圧潰強度が造粒ままのペレットと比較し飛躍的に増大し、高炉用コークス、塊鉱石、焼結鉱に匹敵する圧潰強度を有する。
（2）従来法によるコークス混合試料に較べて高い還元反応性を有し、１０００℃以下での金属鉄生成が可能となる。
（3）高炉で使用される塊鉱石や焼結鉱に較べて格段に優れた還元粉化性（低ＲＤＩ）を有する。
The carbon interior ore (agglomerated ore) produced by the method of the present invention has a carbon substance derived from the gaseous tar of the coarse coke oven gas in the pores formed in the fine iron ore by dehydration of crystallization water by heating. Since it precipitates and is almost completely filled, it has the following high reduction reactivity and crushing strength, and also has good reduced powdering properties.
(1) The crushing strength is dramatically increased compared to as-granulated pellets, and the crushing strength is comparable to blast furnace coke, lump ore, and sintered ore.
(2) It has high reduction reactivity compared with the coke mixed sample by the conventional method, and metallic iron can be generated at 1000 ° C. or less.
(3) It has a reduced powdering property (low RDI) that is far superior to the lump ore and sintered ore used in the blast furnace.
また、（i）化学気相浸透処理の原料ガスとして粗コークス炉ガス（コークス炉で発生したままのコークス炉ガス）を利用し、これに含まれるガス状タールを鉄鉱石に析出させる、（ii）粗コークス炉ガスの顕熱を利用することでペレットを３００〜６００℃という比較的低温で化学気相浸透処理することができる、ことにより低コストに製造できる利点もある。
また、本発明法で製造される炭素内装鉱は、還元剤の少なくとも一部として水素を吹き込む高炉操業に特に適している。
In addition, (i) using a crude coke oven gas (a coke oven gas generated in a coke oven) as a raw material gas for chemical vapor infiltration treatment, and depositing gaseous tar contained therein on iron ore (ii ) By using the sensible heat of the crude coke oven gas, the pellets can be subjected to chemical vapor infiltration treatment at a relatively low temperature of 300 to 600 ° C., whereby there is an advantage that the pellets can be manufactured at low cost.
The carbon interior ore produced by the method of the present invention is particularly suitable for blast furnace operation in which hydrogen is blown as at least a part of the reducing agent.
以下、本発明が得られた実験について説明する。なお、以下の説明では、粗コークス炉ガスを「粗ＣＯＧ」と、コークス炉ガスを「ＣＯＧ」という。また、上述したように、ＣＶＩ処理温度とは原料ガスを接触させてＣＶＩ処理する際のペレット温度である。
実験は以下のようにして行った。
低品位の粉鉄鉱石（Total-Ｆｅ：４６mass％、ＦｅＯ：０．５mass％、ＳｉＯ２：５．５mass％、Ａｌ２Ｏ３：２．７mass％、ＣａＯ：３．７mass％、ＭｇＯ：０．２mass％、結晶水：１０mass％−dry）に水硬性バインダーであるセメントと水を添加し（粉鉄鉱石：セメントの質量比０．９５：０．０５）、造粒機により混合・造粒して粒径が２．０〜３．４ｍｍのペレット（コールドボンドペレット）とし、これを試料として用いた。このペレットのＢＥＴ比表面積は２０ｍ２／ｇであった。なお、以下の説明では、この造粒ままで加熱脱水していないペレットを「生ペレット」という場合がある。
また、実機ＣＯＧから回収したＣＯＧタール（Ｃ：９１mass％、Ｈ：４．７mass％、Ｎ：１．１mass％、Ｓ：０．４mass％−daf）とトルエンの混合溶液を熱分解させ、この熱分解ガスを粗ＣＯＧを模擬した原料ガスとして用いた。
Hereinafter, an experiment in which the present invention was obtained will be described. In the following description, the crude coke oven gas is referred to as “crude COG”, and the coke oven gas is referred to as “COG”. Further, as described above, the CVI processing temperature is a pellet temperature at the time of CVI processing by contacting a raw material gas.
The experiment was performed as follows.
Low-grade fine iron ore (Total-Fe: 46mass%, FeO: 0.5mass%, SiO 2: 5.5mass%, Al 2 O 3: 2.7mass%, CaO: 3.7mass%, MgO: 0. 2mass%, crystal water: 10mass% -dry) Add cement and water as hydraulic binder (powdery ore: cement mass ratio 0.95: 0.05), mix and granulate with granulator Thus, a pellet having a particle size of 2.0 to 3.4 mm (cold bond pellet) was used as a sample. The pellets had a BET specific surface area of 20 m 2 / g. In the following description, pellets that have been granulated and have not been heat-dehydrated may be referred to as “raw pellets”.
Moreover, COG tar (C: 91 mass%, H: 4.7 mass%, N: 1.1 mass%, S: 0.4 mass% -daf) and toluene mixed solution recovered from actual COG are thermally decomposed, and this heat The cracked gas was used as a raw material gas simulating crude COG.
使用した実験装置を図１に示す。この実験装置は、縦長管状の反応器１（石英製）と、この反応器１の上端部分と下端部分を除く中間部分を囲むように設けられる加熱装置２を備えている。反応器１の下部側にはセラミックフィルター３が設けられ、その上にペレットが充填保持される。このセラミックフィルター３上に充填保持されたペレットは、まず脱水加熱処理され、次いでＣＶＩ処理されるので、説明の便宜上、この領域を「処理部ａ」という。
処理部ａ（セラミックフィルター３）の上方には石英ウール４が設けられ、ここにＣＯＧタールとトルエンの混合溶液が滴下される。この石英ウール４に滴下された溶液が加熱されることで熱分解し、粗ＣＯＧを模擬したガス状タール含有熱分解ガスが発生するので、説明の便宜上、この領域を「熱分解部ｂ」という。
The experimental apparatus used is shown in FIG. This experimental apparatus includes a vertically tubular reactor 1 (made of quartz) and a heating device 2 provided so as to surround an intermediate portion excluding an upper end portion and a lower end portion of the reactor 1. A ceramic filter 3 is provided on the lower side of the reactor 1, and pellets are packed and held thereon. Since the pellets filled and held on the ceramic filter 3 are first subjected to dehydration heat treatment and then CVI treatment, this region is referred to as a “treatment part a” for convenience of explanation.
Quartz wool 4 is provided above the processing part a (ceramic filter 3), and a mixed solution of COG tar and toluene is dropped therein. Since the solution dropped on the quartz wool 4 is heated and thermally decomposed to generate a gaseous tar-containing pyrolysis gas that simulates crude COG, this region is referred to as a “thermal decomposition portion b” for convenience of explanation. .
反応器１の上端部分には、ＣＯＧタールとトルエンの混合溶液を供給する供給管５と、Ｈｅ又は５５％Ｈ２／Ｈｅを導入するためのガス導入管６がそれぞれ接続されている。供給管５は送液ポンプ７を介して溶液タンク８に導かれている。また、反応器１の下端部分にはガス導出管９が接続され、このガス導出管９はガス捕集器１０に導かれている。
加熱装置２は、上下２段の加熱部２a，２bで構成され、これら加熱部２a，２bにより処理部ａと熱分解部ｂをそれぞれ別個に加熱し、処理部ａと熱分解部ｂを異なる温度に加熱することができる。
その他、図１において、１１，１２は温度センサー（熱電対）である。
Connected to the upper end of the reactor 1 are a supply pipe 5 for supplying a mixed solution of COG tar and toluene, and a gas introduction pipe 6 for introducing He or 55% H 2 / He. The supply pipe 5 is led to the solution tank 8 via the liquid feed pump 7. A gas outlet pipe 9 is connected to the lower end portion of the reactor 1, and the gas outlet pipe 9 is led to a gas collector 10.
The heating device 2 is composed of two upper and lower heating units 2a and 2b. The heating unit 2a and 2b separately heat the processing unit a and the thermal decomposition unit b, and the processing unit a and the thermal decomposition unit b are different. Can be heated to temperature.
In addition, in FIG. 1, 11 and 12 are temperature sensors (thermocouples).
実験では、ガス導入管６を通じてＨｅを２００ｍｌ／ｍｉｎの流量で導入しつつ、処理部ａ（セラミックフィルター３）に充填保持されたペレットｐを所定の温度に加熱し、粉鉄鉱石の結晶水の脱水を行った。次いで、ガス導入管６を通じてＨｅを２００ｍｌ／ｍｉｎの流量で導入するとともに、同じく供給管５を通じてＣＯＧタールとトルエンの混合溶液（質量比１：１）を０．４ｍｌ／ｍｉｎの流量で供給して熱分解部ｂ（石英ウール４）上に滴下し、この溶液を加熱して熱分解させ、ＣＶＩ処理の原料ガスとなる所定温度の熱分解ガス（ガス状タール含有ガス）を発生させた。この熱分解ガス（以下、「原料ガス」という）を、処理部ａに充填保持されて所定温度に加熱されたペレットｐに供給し、同温度でのＣＶＩ処理を施した。これにより「結晶水の脱水により粉鉄鉱石に生成した細孔内に原料ガスに含まれるガス状タール由来の炭素物質を析出させた炭素内装鉱（塊成鉱）」を得た。
なお、本実験ではＣＶＩ処理時のキャリアガスとしてＨｅを用いたが、実際のＣＯＧに近い５５％Ｈ２／３０％ＣＨ４／５％ＣＯ／３％ＣＯ２／３％Ｈ２Ｏ／４％Ｈｅを用いて行った同様の実験でも、炭素内装鉱の圧潰強度、ＲＤＩ値及び還元反応性は本実験と同等の結果が得られた。
In the experiment, while introducing He through the gas introduction pipe 6 at a flow rate of 200 ml / min, the pellet p filled and held in the processing unit a (ceramic filter 3) is heated to a predetermined temperature, and crystal water of fine iron ore is heated. Dehydration was performed. Next, He is introduced through the gas introduction pipe 6 at a flow rate of 200 ml / min, and a mixed solution of COG tar and toluene (mass ratio 1: 1) is also supplied through the supply pipe 5 at a flow rate of 0.4 ml / min. The solution was dropped on the pyrolysis part b (quartz wool 4), and this solution was heated and pyrolyzed to generate a pyrolysis gas (gaseous tar-containing gas) having a predetermined temperature as a raw material gas for CVI treatment. This pyrolysis gas (hereinafter referred to as “raw material gas”) was supplied to the pellet p that was filled and held in the processing section a and heated to a predetermined temperature, and subjected to CVI treatment at the same temperature. As a result, “carbon interior ore (agglomerated ore) in which a carbon material derived from a gaseous tar contained in the raw material gas was precipitated in pores generated in fine iron ore by dehydration of crystal water” was obtained.
In this experiment, He was used as a carrier gas at the time of CVI treatment, but 55% H 2 /30% CH 4 /5% CO / 3% CO 2 /3% H 2 O / 4%, which is close to the actual COG. In the same experiment conducted using He, the crushing strength, RDI value, and reduction reactivity of the carbon interior ore were the same as those in this experiment.
以上のようにして得られた炭素内装鉱の炭素含有量と圧潰強度を測定した。また、炭素内装鉱の還元率を以下のようにして求め、還元反応性を評価した。すなわち、反応器１内に炭素内装鉱が充填保持された状態で、ガス導入管６からＨｅ又は５５％Ｈ２／Ｈｅを導入し、炭素内装鉱をＨｅ雰囲気又は５５％Ｈ２／Ｈｅ雰囲気中において１０℃／ｍｉｎで１０００℃まで加熱し、その過程で発生するＣＯ・ＣＯ２とＨ２Ｏを各々高速マイクロＧＣと光音響マルチガスモニターで分析し、これらガス状含Ｏ化合物の生成量から還元率を算出した。
また、炭素内装鉱の特性は、主にＸＲＤ、Ｎ２吸着、ＳＥＭ−ＥＤＳ、ラマン分光、圧潰強度試験法（ＪＩＳ Ｍ８７１８）で調べた。
The carbon content and crushing strength of the carbon interior ore obtained as described above were measured. Moreover, the reduction rate of carbon interior ore was calculated | required as follows and the reduction reactivity was evaluated. That is, He or 55% H 2 / He is introduced from the gas introduction pipe 6 in a state where the carbon interior ore is filled and held in the reactor 1, and the carbon interior ore is placed in a He atmosphere or a 55% H 2 / He atmosphere. In this process, CO · CO 2 and H 2 O generated in the process are analyzed with a high-speed micro GC and a photoacoustic multi-gas monitor, and the amount of these gaseous O-containing compounds is determined. The reduction rate was calculated.
The characteristics of carbon interior ore were mainly examined by XRD, N 2 adsorption, SEM-EDS, Raman spectroscopy, crushing strength test method (JIS M8718).
生ペレット（ＢＥＴ比表面積２０ｍ２／ｇ）を１０℃／ｍｉｎで１００〜９００℃まで加熱し、所定温度に到達後、直ちに冷却し、この冷却後のペレットのＢＥＴ比表面積を調べた。その結果を図２に示す。これによれば、加熱温度が３００℃以上になるとペレットを構成する粉鉄鉱石の結晶水が蒸発して細孔が生成するためＢＥＴ比表面積が急激に増大し、３５０℃で極大（６０ｍ２／ｇ）となる。一方、加熱温度が３５０℃を超えると逆にＢＥＴ比表面積は低下しはじめる。これは、急速な結晶水の蒸発のために細孔壁が破壊され、細孔径が拡大したことで、むしろ比表面積が小さくなることによるものと考えられる。図２によると、ペレットの脱水加熱温度は３００〜６００℃程度が好ましく、３２０〜４００℃程度がより好ましいことが判る。 The raw pellets (BET specific surface area 20 m 2 / g) were heated to 100 to 900 ° C. at 10 ° C./min, cooled immediately after reaching a predetermined temperature, and the BET specific surface area of the cooled pellets was examined. The result is shown in FIG. According to this, when the heating temperature becomes 300 ° C. or higher, the crystal water of the fine iron ore constituting the pellets evaporates and pores are generated, so that the BET specific surface area increases rapidly and reaches a maximum at 350 ° C. (60 m 2 / g). On the other hand, when the heating temperature exceeds 350 ° C., the BET specific surface area starts to decrease. This is thought to be due to the fact that the pore surface was destroyed due to rapid evaporation of crystal water and the pore diameter was enlarged, so that the specific surface area was rather reduced. According to FIG. 2, it can be seen that the dehydration heating temperature of the pellet is preferably about 300 to 600 ° C., more preferably about 320 to 400 ° C.
ペレットの脱水加熱温度を３５０℃、５００℃、６００℃の３水準、ＣＶＩ処理温度を３５０℃、５００℃、６００℃の３水準とし、原料ガス温度を３５０〜７００℃の範囲で変化させて炭素内装鉱を製造した。これら製造例では、ペレットの脱水加熱とＣＶＩ処理を、それぞれ１ｈｒで行った。
このようにして得られた炭素内装鉱について、ＢＥＴ比表面積と圧潰強度を調べた結果を図３、図４に示す。図３は、脱水加熱後・ＣＶＩ処理前のペレットと炭素内装鉱のＢＥＴ比表面積を示している。また、図４は、脱水加熱前の生ペレットと炭素内装鉱の圧潰強度を示している。
The pellets are dehydrated and heated at three levels of 350 ° C., 500 ° C., and 600 ° C., the CVI treatment temperature is set at three levels of 350 ° C., 500 ° C., and 600 ° C., and the raw material gas temperature is changed within the range of 350 to 700 ° C. Produced interior ore. In these production examples, dehydration heating and CVI treatment of the pellets were each performed for 1 hr.
The results of examining the BET specific surface area and the crushing strength of the carbon interior ore thus obtained are shown in FIGS. FIG. 3 shows the BET specific surface area of pellets and carbon interior ore after dehydration heating and before CVI treatment. FIG. 4 shows the crushing strength of raw pellets and carbon interior ore before dehydration heating.
図３によれば、タールを含有する原料ガスでＣＶＩ処理して得られた炭素内装鉱のＢＥＴ比表面積は、いずれの温度条件で得られたものであっても、脱水加熱後・ＣＶＩ処理前のペレットに較べて大きく低下している。これは、タールを含有する原料ガスでＣＶＩ処理を行ったことにより、原料ガスのタールに由来する炭素物質がペレットを構成する粉鉄鉱石の細孔に析出して充填されたことによるものと考えられる。また、ＣＶＩ処理温度３５０℃、原料ガス温度５００℃以上としたもの、特に７００℃のものが、ＢＥＴ比表面積が特に低くなっている。これは、粉鉄鉱石の細孔内に炭素物質が特に密に充填されためであると考えられる。 According to FIG. 3, the BET specific surface area of carbon interior ore obtained by CVI treatment with a raw material gas containing tar is obtained after dehydration heating and before CVI treatment, regardless of the temperature conditions. Compared to the pellets of the above, it is greatly reduced. This is thought to be due to the fact that the carbon material derived from the tar of the raw material gas was deposited and filled in the pores of the fine iron ore constituting the pellets by performing the CVI treatment with the raw material gas containing tar. It is done. Further, the CET treatment temperature of 350 ° C. and the raw material gas temperature of 500 ° C. or higher, particularly 700 ° C., have a particularly low BET specific surface area. This is considered to be because the carbon material is particularly closely packed in the pores of the fine iron ore.
また、図４によれば、タールを含有する原料ガスでＣＶＩ処理して得られた炭素内装鉱は、生ペレットに較べて圧潰強度が増加している。これは、タールを含有する原料ガスでＣＶＩ処理を行ったことにより、原料ガスのタールに由来する炭素物質がペレットを構成する粉鉄鉱石の細孔に析出して充填されることにより、強度が高まったものと考えられる。また、炭素内装鉱の圧潰強度は、原料ガス温度が高く且つＣＶＩ処理温度が低い時に大きい傾向がある。 Moreover, according to FIG. 4, the crushing strength of the carbon interior ore obtained by the CVI treatment with the raw material gas containing tar is increased as compared with the raw pellets. This is because the carbon material derived from the tar of the source gas precipitates and fills the fine pores of the fine iron ore constituting the pellet by performing the CVI treatment with the source gas containing tar. It is thought that it was expensive. Further, the crushing strength of carbon interior ore tends to be large when the raw material gas temperature is high and the CVI treatment temperature is low.
なお、この実験では原料ガス温度の最高は７００℃であるが、図３及び図４に示される傾向から、原料ガス温度が７００℃超（〜１０００℃程度）であっても、同様の効果が得られることが容易に推認できる。一般に、粗ＣＯＧはコークス炉から１０００℃前後で排出されるので、配管内でなるべく温度降下しないようにすることで、最高１０００℃程度の温度で利用でき、したがって、原料ガス温度は１０００℃程度まで許容されると考えられる。
以上の結果から、ＣＶＩ処理温度（ＣＶＩ処理する際のペレット温度）は３００〜６００℃が好ましく、３００〜４００℃がより好ましいこと、また、ＣＶＩ処理に用いる原料ガスの温度は５００〜１０００℃が好ましく、７００〜１０００℃がより好ましいことが判る。
In this experiment, the maximum raw material gas temperature is 700 ° C., but from the tendency shown in FIG. 3 and FIG. 4, even if the raw material gas temperature exceeds 700 ° C. (about 1000 ° C.), the same effect is obtained. It can be easily guessed that it is obtained. Generally, since crude COG is discharged from the coke oven at around 1000 ° C., it can be used at a maximum temperature of about 1000 ° C. by avoiding a temperature drop in the piping as much as possible. It is considered acceptable.
From the above results, the CVI treatment temperature (pellet temperature during CVI treatment) is preferably 300 to 600 ° C, more preferably 300 to 400 ° C, and the temperature of the raw material gas used for CVI treatment is 500 to 1000 ° C. It can be seen that 700 to 1000 ° C. is more preferable.
脱水加熱温度３５０℃、原料ガス温度７００℃、ＣＶＩ処理温度３５０℃の条件で得られた炭素内装鉱について、その炭素含有量と圧潰強度に及ぼすＣＶＩ処理時間の影響を調べた。図５（ａ）に、ＣＶＩ処理時間と炭素内装鉱の炭素含有量との関係を示す。これによると、炭素内装鉱の炭素含有量は処理時間が約９０ｍｉｎまでは直線的に増加し、その後ほぼ一定となり、その値は１８０〜２４０ｍｉｎまでに１８mass％−dryに達している。図５（ｂ）に、ＣＶＩ処理時間と炭素内装鉱の圧潰強度との関係を示す。これによると、ＣＶＩ処理時間が約２０ｍｉｎ程度までは圧潰強度はほとんど変化しないが、４０〜９０ｍｉｎになると大きく増大し、約１８０ｍｉｎ以上ではほぼ１０ｄａＮ（単位：ｄａＮ＝デカニュートン）に達している。以上の結果から、ＣＶＩ処理時間は６０ｍｉｎ以上が好ましく、９０ｍｉｎ以上がより好ましく、１８０ｍｉｎ以上が特に好ましいことが判った。 For carbon interior ore obtained under conditions of a dehydration heating temperature of 350 ° C., a raw material gas temperature of 700 ° C., and a CVI treatment temperature of 350 ° C., the influence of the CVI treatment time on the carbon content and crushing strength was investigated. FIG. 5A shows the relationship between the CVI treatment time and the carbon content of the carbon interior ore. According to this, the carbon content of the carbon interior ore increases linearly until the processing time is about 90 min, and becomes almost constant thereafter, and the value reaches 18 mass% -dry by 180 to 240 min. FIG. 5B shows the relationship between the CVI treatment time and the crushing strength of the carbon interior ore. According to this, the crushing strength hardly changes until the CVI processing time is about 20 min. However, it greatly increases when the CVI processing time is about 40 to 90 min. From the above results, it was found that the CVI processing time is preferably 60 min or more, more preferably 90 min or more, and particularly preferably 180 min or more.
図６は、図５（ａ），（ｂ）に示される炭素内装鉱の炭素含有量と圧潰強度との関係を整理して示したものである。これによれば、炭素内装鉱の圧潰強度は炭素含有量が約１０mass％−dryを上回ると顕著に増加し、炭素含有量が１８mass％−dryでは１０ｄａＮに達している。この１０ｄａＮという圧潰強度は、実際の高炉で使用されているコークス（Ｄ１５０ ６＝８７．１）の同粒径の試料の強度（１０ｄａＮ）に匹敵するものであり、高い圧潰強度が得られることが判る。
炭素内装鉱の圧潰強度は、炭素含有量が１０mass％−dry未満では殆ど変化はないが、炭素含有量が１０mass％−dry以上になると急激に増加している。これは、炭素含有量が１０mass％−dry未満の段階では、炭素物質の析出が主に細孔の枝部に限られるため、圧潰強度の増加にほとんど寄与しないのに対して、炭素含有量が１０mass％−dry以上になると炭素物質の析出が細孔の幹部にも生じ、圧潰強度の増加に寄与するためであると考えられる。
FIG. 6 shows the relationship between the carbon content and the crushing strength of the carbon interior ore shown in FIGS. 5 (a) and 5 (b). According to this, the crushing strength of the carbon interior ore increases remarkably when the carbon content exceeds about 10 mass% -dry, and reaches 10 daN when the carbon content is 18 mass% -dry. The crushing strength of 10 daN is comparable to the strength (10 daN) of a sample having the same particle size of coke (D 150 6 = 87.1) used in an actual blast furnace, and a high crushing strength can be obtained. I understand.
The crushing strength of the carbon interior ore hardly changes when the carbon content is less than 10 mass% -dry, but rapidly increases when the carbon content becomes 10 mass% -dry or more. This is because, at a stage where the carbon content is less than 10 mass% -dry, the precipitation of the carbon material is mainly limited to the branches of the pores, so that it hardly contributes to the increase in crushing strength, whereas the carbon content is When the mass is 10 mass% -dry or more, it is considered that the carbon material is also precipitated in the trunk portion of the pores and contributes to the increase in crushing strength.
次に、炭素内装鉱の還元粉化指数（ＲＤＩ）について調べた。
本実験では、得られる炭素内装鉱量の面からＲＤＩ試験（試料５００ｇを３０％ＣＯ、５５０℃で３０ｍｉｎ処理後、回転ドラムで９００回転、目開き３ｍｍで篩い分け後、３ｍｍ以下の試料割合を算出）を実施するのは難しいため、まずＲＤＩ値が既知の粒径２〜３．４ｍｍの塊成鉱及び焼結鉱を５５％Ｈ２／Ｈｅ雰囲気中において５００℃で還元処理した後の圧潰強度を測定し、それらの圧潰強度とＲＤＩ値との関係性を調べた。次に、その相関関係に基づき、５５％Ｈ２／Ｈｅ雰囲気中において５００℃で還元処理した炭素内装鉱の圧潰強度からＲＤＩ値を推算した。使用した塊鉱石と焼結鉱のＲＤＩ値と化学組成を表１に示すとともに、圧潰強度とＲＤＩ値の関係を図７に示す。これによれば、圧潰強度とＲＤＩ値の間には、比較的良好な負の相関が認められる。この相関関係に基づき、炭素内装鉱の圧潰強度からＲＤＩ値の推算を行なった結果を図８に示す。炭素内装鉱は脱水加熱温度３５０℃、原料ガス温度７００℃、ＣＶＩ処理温度３５０℃、ＣＶＩ処理時間１８０ｍｉｎの条件で得られたものである。図８によれば、炭素内装鉱のＲＤＩ値は１５程度と見積もられ、この値は一般的に高炉で使用される塊鉱石や焼結鉱のＲＤＩ値（３０〜４０）と較べてかなり小さく、良好なＲＤＩ値が得られることが判る。
Next, the reduced powder index (RDI) of the carbon interior ore was examined.
In this experiment, the RDI test (500 g of sample was treated for 30 min at 30% CO and 550 ° C. for 30 min, after sieving with a rotating drum, with a mesh opening of 3 mm, and a sample ratio of 3 mm or less in this experiment. It is difficult to carry out the calculation), so first crushing after reducing the agglomerated or sintered ore with a known RDI value of 2 to 3.4 mm in a 55% H 2 / He atmosphere at 500 ° C. The strength was measured, and the relationship between the crushing strength and the RDI value was examined. Next, based on the correlation, the RDI value was estimated from the crushing strength of the carbon interior ore reduced at 500 ° C. in a 55% H 2 / He atmosphere. Table 1 shows the RDI value and chemical composition of the lump ore and sintered ore used, and FIG. 7 shows the relationship between the crushing strength and the RDI value. According to this, a relatively good negative correlation is recognized between the crushing strength and the RDI value. Based on this correlation, the result of estimating the RDI value from the crushing strength of the carbon interior ore is shown in FIG. The carbon interior ore was obtained under the conditions of a dehydration heating temperature of 350 ° C., a raw material gas temperature of 700 ° C., a CVI treatment temperature of 350 ° C., and a CVI treatment time of 180 minutes. According to FIG. 8, the RDI value of carbon interior ore is estimated to be about 15, which is considerably smaller than the RDI value (30-40) of massive ore and sintered ore generally used in blast furnaces. It can be seen that a good RDI value can be obtained.
次に、炭素含有量が１８mass％−dryの炭素内装鉱について、炭素の分布状態をＳＥＭ−ＥＤＳで調べた。その結果を図９に示す。炭素内装鉱は脱水加熱温度３５０℃、原料ガス温度７００℃、ＣＶＩ処理温度３５０℃の条件で得られたものである。図９の「ａ」は炭素内装鉱の粒子断面のＳＥＭ画像であり、図９「ｂ」はそのＳＥＭ画像中の破線に沿ったＥＤＳによる線分析の結果である。また、図９「ｃ」と「ｄ」は、それぞれ粒子断面のＦｅとＣのＥＤＳによる面分析の結果である。線分析（図９「ｂ」）と面分析（図９「ｃ」、「ｄ」）の結果から、炭素は粒子表面に比較的多く存在するものの、内部にもほぼ均一に分布していることが判る。また、ラマン分光法により導入された炭素の化学構造を調べた結果、炭素は主にアモルファス形態で存在していた。この炭素内装鉱を調製する前の３５０℃に加熱（脱水）したペレットの細孔容積の測定値は０．０６ｃｍ３／ｇであったが、炭素内装鉱中の炭素をアモルファスと仮定すると、その細孔容積に基づいた炭素含有量は１２mass％−dryと見積もられ、細孔には理論値以上の炭素が充填されていたことになる。この結果は、ＣＶＩ処理によりペレット（粉鉄鉄鉱石）の細孔内にタール由来の炭素物質を完全充填可能であることを示している。また、理論値以上の炭素含有量は、図９「ｂ」、「ｄ」に示すように粒子表面上への炭素析出によるものと推測される。 Next, about the carbon interior ore whose carbon content is 18 mass% -dry, the carbon distribution state was investigated by SEM-EDS. The result is shown in FIG. The carbon interior ore was obtained under the conditions of a dehydration heating temperature of 350 ° C., a raw material gas temperature of 700 ° C., and a CVI treatment temperature of 350 ° C. “A” in FIG. 9 is an SEM image of a particle cross section of carbon interior ore, and FIG. 9 “b” is a result of line analysis by EDS along a broken line in the SEM image. Further, FIGS. 9C and 9D show the results of surface analysis by EDS of Fe and C in the particle cross section, respectively. From the results of line analysis (Fig. 9 "b") and surface analysis (Figs. 9 "c" and "d"), although carbon is present in a relatively large amount on the particle surface, it is almost uniformly distributed inside. I understand. Moreover, as a result of investigating the chemical structure of carbon introduced by Raman spectroscopy, carbon was mainly present in an amorphous form. The measured pore volume of the pellets heated (dehydrated) to 350 ° C. before preparing the carbon interior ore was 0.06 cm 3 / g, but assuming that the carbon in the carbon interior ore is amorphous, The carbon content based on the pore volume was estimated to be 12 mass% -dry, and the pores were filled with carbon of more than the theoretical value. This result shows that the carbon material derived from tar can be completely filled in the pores of the pellet (pulverized iron ore) by the CVI treatment. Further, the carbon content exceeding the theoretical value is presumed to be due to carbon deposition on the particle surface as shown in FIGS. 9B and 9D.
炭素内装鉱の還元反応性を明らかにするため、Ｈｅ雰囲気と水素還元高炉を模擬した５５％Ｈ２／Ｈｅ雰囲気中で炭素内装鉱を加熱（還元処理）し、この加熱時におけるガス状含Ｏ化合物の生成速度の推移を調べた。炭素内装鉱は脱水加熱温度３５０℃、原料ガス温度７００℃、ＣＶＩ処理温度３５０℃の条件で得られたものである。図１０は、その結果を示すものであり、（ａ）はＨｅ雰囲気で加熱した場合、（ｂ）は５５％Ｈ２／Ｈｅ雰囲気中で加熱した場合を示している。
図１０（ａ）に示すＨｅ雰囲気中での加熱では、ＣＯとＣＯ２の生成は３００〜４００℃で始まり、それらの生成速度は７００℃前後に主ピークがある。Ｈ２Ｏは３００℃付近から発生し始め、約８００℃に生成速度のピークがある。一方、図１０（ｂ）に示す５５％Ｈ２／Ｈｅ雰囲気中での加熱でも、ガス状含Ｏ化合物の生成は３００〜４００℃から認められ、Ｈ２Ｏは約４００℃、６００℃のショルダーピークの他に、７５０℃前後に主ピークがある。ＣＯとＣＯ２は約６００℃に生成速度のピークがあり、前者では８００〜９００℃にも弱いピークが認められる。
In order to clarify the reduction reactivity of carbon interior ore, the carbon interior ore is heated (reduction treatment) in a 55% H 2 / He atmosphere simulating a He atmosphere and a hydrogen reduction blast furnace. The transition of the compound formation rate was examined. The carbon interior ore was obtained under the conditions of a dehydration heating temperature of 350 ° C., a raw material gas temperature of 700 ° C., and a CVI treatment temperature of 350 ° C. FIG. 10 shows the results, where (a) shows the case of heating in a He atmosphere, and (b) shows the case of heating in a 55% H 2 / He atmosphere.
In the heating in the He atmosphere shown in FIG. 10A, the generation of CO and CO 2 starts at 300 to 400 ° C., and the generation rate thereof has a main peak around 700 ° C. H 2 O begins to be generated around 300 ° C., and has a peak production rate at about 800 ° C. On the other hand, even in the heating in the 55% H 2 / He atmosphere shown in FIG. 10B, the generation of the gaseous O-containing compound was observed from 300 to 400 ° C., and H 2 O was about 400 ° C. and 600 ° C. shoulder. In addition to the peak, there is a main peak around 750 ° C. CO and CO 2 have a peak production rate at about 600 ° C., and the former has a weak peak at 800 to 900 ° C.
このようにガス状含Ｏ化合物の脱離挙動は、Ｈｅ雰囲気中と５５％Ｈ２／Ｈｅ雰囲気中では異なっている。１０００℃で６０ｍｉｎ保持したときのガス状含Ｏ化合物の生成量は、Ｈｅ雰囲気中ではＣＯ２＜Ｈ２Ｏ＜ＣＯ、５５％Ｈ２／Ｈｅ雰囲気中ではＣＯ２＜＜ＣＯ＜Ｈ２Ｏの順となった。以上の結果は、Ｈｅ雰囲気中での炭素内装鉱中の酸化鉄の還元は、主に細孔内に充填された炭素による直接還元によって進行するものの、一部は加熱過程で発生するＣＯやＨ２が寄与していることを示していると考えられる。一方、５５％Ｈ２／Ｈｅ雰囲気中では、水素還元が支配的であるものの、細孔内に充填された炭素による直接還元も生じており、間接還元の寄与は小さいものと推測される。また、Ｈｅ雰囲気中でのＣＯ２生成量は１４％であるのに対して、５５％Ｈ２／Ｈｅ雰囲気中でのＣＯ２生成量は３．５％であり、５５％Ｈ２／Ｈｅ雰囲気中では、Ｈｅ雰囲気中でのＣＯ２生成量の７５％を低減可能であった。このことから、水素雰囲気下での炭素内装鉱の還元時にはＣＯ２排出量の削減が期待できる。 As described above, the desorption behavior of the gaseous O-containing compound is different between the He atmosphere and the 55% H 2 / He atmosphere. The amount of gaseous O-containing compound produced when held at 1000 ° C. for 60 min is CO 2 << H 2 O <CO in He atmosphere and CO 2 << CO <H 2 O in 55% H 2 / He atmosphere. It became order. The above results indicate that although reduction of iron oxide in carbon interior ore in He atmosphere proceeds mainly by direct reduction with carbon filled in the pores, some of CO and H generated in the heating process 2 is considered to be contributing. On the other hand, in a 55% H 2 / He atmosphere, although hydrogen reduction is dominant, direct reduction by carbon filled in the pores also occurs, and it is estimated that the contribution of indirect reduction is small. Further, CO 2 generated amount in a He atmosphere whereas a 14%, CO 2 generation amount of 55% H 2 / He atmosphere is 3.5%, 55% H 2 / He atmosphere In particular, 75% of the amount of CO 2 produced in the He atmosphere could be reduced. From this, reduction of CO 2 emissions can be expected when reducing carbon interior ore in a hydrogen atmosphere.
図１１は、炭素内装鉱をＨｅ雰囲気中と５５％Ｈ２／Ｈｅ雰囲気中で加熱した際のガス状含Ｏ化合物の生成量から算出した炭素内装鉱の還元挙動（還元率の推移）を示している。炭素内装鉱は脱水加熱温度３５０℃、原料ガス温度７００℃、ＣＶＩ処理温度３５０℃の条件で得られたものである。また、比較のため、５００℃で加熱脱水したペレットと粉コークス（高炉で使用される通常強度のコークスを＜７５μｍに粉砕したコークス）の混合物（コークス混合試料）をＨｅ雰囲気中で加熱した場合の還元挙動と、５００℃で加熱脱水したペレットを５５％Ｈ２／Ｈｅ雰囲気中で加熱した場合の還元挙動も併せて示している。図１１によれば、Ｈｅ雰囲気と５５％Ｈ２／Ｈｅ雰囲気中での炭素内装鉱の還元率は、それぞれ５００〜６００℃から急激に増加し、１０００℃で６０ｍｉｎ保持した後は８５〜９５％に達しており、このような炭素内装鉱の還元速度は、コークス混合試料と比較して極めて大きい。なお、炭素内装鉱を５５％Ｈ２／Ｈｅ雰囲気中で加熱した場合であっても、その還元速度は、５００℃で加熱脱水したペレットを５５％Ｈ２／Ｈｅ雰囲気中で加熱した場合に較べて小さい。これは、炭素内装鉱では細孔内に炭素物質が充填されるため、酸化鉄と水素の接触性の低下が生じたことによるものと考えられる。 FIG. 11 shows the reduction behavior (change in reduction rate) of carbon interior ore calculated from the amount of gaseous O-containing compound produced when carbon interior ore is heated in a He atmosphere and 55% H 2 / He atmosphere. ing. The carbon interior ore was obtained under the conditions of a dehydration heating temperature of 350 ° C., a raw material gas temperature of 700 ° C., and a CVI treatment temperature of 350 ° C. For comparison, when a mixture (coke mixed sample) of pellets dehydrated by heating at 500 ° C. and powder coke (coke obtained by crushing normal strength coke used in a blast furnace to <75 μm) is heated in a He atmosphere. The reduction behavior and the reduction behavior when the pellets dehydrated by heating at 500 ° C. are heated in a 55% H 2 / He atmosphere are also shown. According to FIG. 11, the reduction rate of carbon interior ore in He atmosphere and 55% H 2 / He atmosphere increases rapidly from 500 to 600 ° C., respectively, and 85 to 95% after holding at 1000 ° C. for 60 min. The reduction rate of such carbon interior ore is extremely large compared with the coke mixed sample. Even when the carbon interior ore is heated in a 55% H 2 / He atmosphere, the reduction rate is higher than when the pellets heated and dehydrated at 500 ° C. are heated in a 55% H 2 / He atmosphere. Small. This is considered to be due to the decrease in the contact between iron oxide and hydrogen because the carbon interior ore is filled with carbon material in the pores.
表２に、炭素内装鉱をＨｅ雰囲気と５５％Ｈ２／Ｈｅ雰囲気中でそれぞれ各温度で加熱した後の鉄の化学形態をＸＲＤで調べた結果を示す。炭素内装鉱は脱水加熱温度３５０℃、原料ガス温度７００℃、ＣＶＩ処理温度３５０℃の条件で得られたものである。表２によれば、炭素内装鉱中の元々のＦｅの形態はＦｅ２Ｏ３とＦｅ３Ｏ４であるが、Ｈｅ雰囲気中で６００℃に加熱すると前者のピークが消失し、Ｆｅ３Ｏ４のみとなる。温度をさらに上げると、７００℃でＦｅＯが生成し、８００℃からはα−Ｆｅのシグナルも認められ、９００℃以上ではα−Ｆｅの回折線のみが現われる。一方、５５％Ｈ２／Ｈｅ雰囲気中で加熱すると、５００℃でＦｅ３Ｏ４単一相となり、６００℃の低温からＦｅＯに加え、α−Ｆｅに帰属するピークが出現し、８００℃では後者のみとなり、低温から金属鉄が生成する。以上のように、炭素内装鉱は１０００℃以下での金属鉄生成が可能となる。 Table 2 shows the results obtained by examining the chemical form of iron by XRD after heating the carbon interior ore in a He atmosphere and a 55% H 2 / He atmosphere at each temperature. The carbon interior ore was obtained under the conditions of a dehydration heating temperature of 350 ° C., a raw material gas temperature of 700 ° C., and a CVI treatment temperature of 350 ° C. According to Table 2, the original Fe forms in the carbon interior ore are Fe 2 O 3 and Fe 3 O 4 , but the former peak disappears when heated to 600 ° C. in a He atmosphere, and Fe 3 O 4 It becomes only. When the temperature is further increased, FeO is generated at 700 ° C., an α-Fe signal is observed from 800 ° C., and only an α-Fe diffraction line appears at 900 ° C. or higher. On the other hand, when heated in a 55% H 2 / He atmosphere, it becomes an Fe 3 O 4 single phase at 500 ° C., and a peak attributed to α-Fe appears in addition to FeO from a low temperature of 600 ° C., and the latter at 800 ° C. Only, and metallic iron is produced from low temperature. As described above, the carbon interior ore can produce metallic iron at 1000 ° C. or lower.
図１２は、図１１の還元率の推移に伴う炭素内装鉱の圧潰強度の推移を示している。また、比較のために、表１に示した塊鉱石と５００℃で加熱脱水したペレットを５５％Ｈ２／Ｈｅ雰囲気中で加熱した場合の圧潰強度の推移も併せて示した。図１２によれば、塊鉱石と加熱脱水したペレットの圧潰強度は、還元率４０％までに大きく低下している。一方、炭素内装鉱では、Ｈｅ雰囲気中では還元率３０％以上から圧潰強度の減少が認められたものの、５５％Ｈ２／Ｈｅ雰囲気中では還元率５０％まで強度は維持されている。 FIG. 12 shows the transition of the crushing strength of the carbon interior ore with the transition of the reduction rate of FIG. For comparison, the change in crushing strength when the ore shown in Table 1 and pellets heated and dehydrated at 500 ° C. in a 55% H 2 / He atmosphere are also shown. According to FIG. 12, the crushing strength of the lump ore and the pellets dehydrated by heating is greatly reduced to a reduction rate of 40%. On the other hand, in the carbon interior ore, although the reduction of crushing strength was recognized from a reduction rate of 30% or more in a He atmosphere, the strength was maintained up to a reduction rate of 50% in a 55% H 2 / He atmosphere.
炭素含有量が１８mass％−dryの炭素内装鉱を、Ｈｅ雰囲気中で還元率５０％まで還元した場合、炭素含有量は９mass％−dryに低下し、一方、５５％Ｈ２／Ｈｅ雰囲気中で還元率５０％まで還元した場合、炭素含有量は１３mass％−dryに低下し、前者で炭素含有量の大きな低下が認められた。また、この炭素内装鉱のＮ２吸着による細孔分析の結果から、ＣＶＩ処理後に消失した２ｎｍ付近の細孔径ピークの復元を確認した。そのため、還元率の増加に伴う圧潰強度の低下は、酸化鉄−炭素間の接触界面での直接還元による炭素消費により生じた細孔の生成に基因するものと推測される。これらの結果から、塊鉱石の強度低下が著しく生じる還元率５０％までの強度低下を、炭素内装鉱では改善可能であることが判った。 Carbon interior ore 18 mass% -dry carbon content, when reduced to reduced rate of 50% in He atmosphere, the carbon content is reduced to 9mass% -dry, whereas, in 55% H 2 / He atmosphere When the reduction rate was reduced to 50%, the carbon content decreased to 13 mass% -dry, and a large decrease in the carbon content was observed in the former. Further, from the result of pore analysis by N 2 adsorption of this carbon interior ore, it was confirmed that the pore diameter peak near 2 nm disappeared after CVI treatment. Therefore, it is assumed that the reduction in the crushing strength accompanying the increase in the reduction rate is caused by the generation of pores caused by carbon consumption by direct reduction at the iron oxide-carbon contact interface. From these results, it was found that the reduction in strength up to a reduction rate of 50% in which the strength reduction of the massive ore is remarkable can be improved in the carbon interior ore.
以上の実験から、結晶水を含有する粉鉄鉱石と水硬性バインダーの混合物を造粒して得られたペレットを、本発明条件に従い加熱脱水した後、粗ＣＯＧを原料ガスとしてＣＶＩ処理することにより、高い還元反応性と圧潰強度を有するとともに、良好な還元粉化性（低ＲＤＩ）を有する炭素内装鉱が製造できることが判った。また、ＣＶＩ処理の原料ガスとして粗ＣＯＧを利用できること、粗ＣＯＧの顕熱を利用することでペレットを３００〜６００℃という比較的低温でＣＶＩ処理できること、により炭素内装鉱を低コストに製造できることも確認できた。また、この炭素内装鉱は、水素雰囲気でのＣＯ２生成量が少ないことなどから、還元剤の少なくとも一部として水素を用いる水素還元高炉に特に適していると言える。 From the above experiment, pellets obtained by granulating a mixture of fine iron ore containing crystallization water and a hydraulic binder were heated and dehydrated according to the conditions of the present invention, and then subjected to CVI treatment using crude COG as a raw material gas. It was found that a carbon interior ore having high reduction reactivity and crushing strength and good reduction powdering properties (low RDI) can be produced. In addition, it is possible to use crude COG as a raw material gas for CVI treatment, and to produce pellets at a relatively low temperature of 300 to 600 ° C. by using sensible heat of crude COG, thereby producing carbon interior ore at low cost. It could be confirmed. In addition, this carbon interior ore can be said to be particularly suitable for a hydrogen reduction blast furnace using hydrogen as at least a part of the reducing agent because of the small amount of CO 2 produced in a hydrogen atmosphere.
１ 反応器
２ 加熱装置
２a，２b 加熱部
３ セラミックフィルター
４ 石英ウール
５ 供給管
６ ガス導入管
７ 送液ポンプ
８ 溶液タンク
９ ガス導出管
１０ ガス捕集器
１１ 温度センサー
１２ 温度センサー
ａ 処理部
ｂ 熱分解部
ｐ ペレット
DESCRIPTION OF SYMBOLS 1 Reactor 2 Heating apparatus 2a, 2b Heating part 3 Ceramic filter 4 Quartz wool 5 Supply pipe 6 Gas introduction pipe 7 Liquid feed pump 8 Solution tank 9 Gas outlet pipe 10 Gas collector 11 Temperature sensor 12 Temperature sensor a Processing part b Pyrolysis part p pellet
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