JP6064341B2 - How to remove sulfur from desulfurized slag - Google Patents
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- JP6064341B2 JP6064341B2 JP2012051113A JP2012051113A JP6064341B2 JP 6064341 B2 JP6064341 B2 JP 6064341B2 JP 2012051113 A JP2012051113 A JP 2012051113A JP 2012051113 A JP2012051113 A JP 2012051113A JP 6064341 B2 JP6064341 B2 JP 6064341B2
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- 239000002893 slag Substances 0.000 title claims description 119
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 title claims description 66
- 239000011593 sulfur Substances 0.000 title claims description 66
- 229910052717 sulfur Inorganic materials 0.000 title claims description 66
- 238000006477 desulfuration reaction Methods 0.000 claims description 91
- 230000023556 desulfurization Effects 0.000 claims description 91
- 238000000034 method Methods 0.000 claims description 52
- 229910052751 metal Inorganic materials 0.000 claims description 47
- 239000002184 metal Substances 0.000 claims description 47
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 46
- 230000008569 process Effects 0.000 claims description 27
- 238000009628 steelmaking Methods 0.000 claims description 25
- 229910052742 iron Inorganic materials 0.000 claims description 23
- 238000004064 recycling Methods 0.000 claims description 16
- 238000007670 refining Methods 0.000 claims description 12
- 238000001816 cooling Methods 0.000 claims description 8
- 238000005261 decarburization Methods 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 7
- 238000005245 sintering Methods 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 150000003464 sulfur compounds Chemical class 0.000 claims description 4
- 230000003009 desulfurizing effect Effects 0.000 claims description 2
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 64
- 239000000292 calcium oxide Substances 0.000 description 32
- 235000012255 calcium oxide Nutrition 0.000 description 32
- 239000007789 gas Substances 0.000 description 15
- 238000010438 heat treatment Methods 0.000 description 11
- 239000003795 chemical substances by application Substances 0.000 description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 8
- 239000004568 cement Substances 0.000 description 7
- 229910000831 Steel Inorganic materials 0.000 description 6
- 239000010959 steel Substances 0.000 description 6
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 5
- 239000003546 flue gas Substances 0.000 description 5
- 239000002904 solvent Substances 0.000 description 4
- 230000004907 flux Effects 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- 229910004261 CaF 2 Inorganic materials 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 239000011400 blast furnace cement Substances 0.000 description 2
- 238000001354 calcination Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 150000001875 compounds Chemical group 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 239000011398 Portland cement Substances 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 229910052602 gypsum Inorganic materials 0.000 description 1
- 230000012447 hatching Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 1
- 239000000347 magnesium hydroxide Substances 0.000 description 1
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 1
- 238000007885 magnetic separation Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000010907 mechanical stirring Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000010079 rubber tapping Methods 0.000 description 1
- 230000009528 severe injury Effects 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 125000000101 thioether group Chemical group 0.000 description 1
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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
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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
- Y02P10/25—Process efficiency
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- Processing Of Solid Wastes (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
- Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
Description
本発明は、溶銑の脱硫処理によって発生した、ＣａＯを主成分とする脱硫スラグからこの脱硫スラグに含有される硫黄を除去し、硫黄含有量の低下した脱硫スラグを製銑工程または製鋼工程にてＣａＯ源として有効活用することを可能とするための、脱硫スラグからの硫黄の除去方法に関する。 The present invention removes sulfur contained in this desulfurization slag from the desulfurization slag containing CaO as a main component generated by the desulfurization treatment of hot metal, and the desulfurization slag having a reduced sulfur content is produced in a steelmaking process or a steelmaking process. The present invention relates to a method for removing sulfur from desulfurized slag to enable effective use as a CaO source.
鉄鋼製品の材料特性の向上及び品質要求の高まりを受け、溶銑における予備精錬として溶銑の脱硫処理が鉄鋼各社において行われている。この脱硫処理においては、溶銑中の硫黄は、一般的に、ＣａＯを主成分とするフラックス（脱硫剤）の添加、並びに、このフラックスと溶銑との攪拌処理により、硫化物形態となってスラグへ除去されている。尚、溶銑の脱硫処理とは、転炉にて脱炭精錬する前の溶銑段階において、溶銑中の硫黄を除去する処理のことである。 In response to the improvement in material properties of steel products and the increasing demand for quality, hot metal desulfurization treatment is being carried out at each steel company as a preliminary refining of hot metal. In this desulfurization treatment, the sulfur in the hot metal generally becomes a sulfide form by adding a flux (desulfurization agent) mainly composed of CaO and stirring the flux and the hot metal into slag. Has been removed. The hot metal desulfurization treatment is a treatment for removing sulfur in the hot metal in the hot metal stage before decarburization and refining in a converter.
溶銑への脱硫処理比率の上昇に伴って、脱硫スラグの発生量が増加する。但し、この脱硫スラグには硫黄が含まれており、水の存在する環境下で脱硫スラグを再利用すると硫黄（黄水）が溶出し、環境に悪影響を与える懸念があり、脱硫スラグの利材化には大きな制約のあるのが実態である。また、溶銑の脱硫処理におけるＣａＯの脱硫剤としての利用効率は高々数％程度であり、脱硫処理で使用されるＣａＯの大部分は、未利用のまま脱硫スラグとして製鉄所外へ排出されている。 The amount of desulfurization slag generated increases as the desulfurization treatment ratio to hot metal increases. However, this desulfurized slag contains sulfur, and if desulfurized slag is reused in an environment where water is present, sulfur (yellow water) may elute and adversely affect the environment. The reality is that there are significant restrictions on the conversion. Moreover, the utilization efficiency of CaO as a desulfurization agent in the desulfurization treatment of hot metal is at most several percent, and most of the CaO used in the desulfurization treatment is discharged outside the steelworks as desulfurization slag without being used. .
そこで、これらの課題を解決するべく以下のような技術が提案されている。 In order to solve these problems, the following techniques have been proposed.
例えば、特許文献１には、溶銑の脱硫処理で発生した高温の脱硫スラグを高温のままリサイクルし、新たな溶銑の脱硫処理に使用することでＣａＯの利用効率を高め、脱硫スラグの排出量を削減する技術が開示されている。 For example, Patent Document 1 discloses that high-temperature desulfurization slag generated by hot metal desulfurization treatment is recycled at a high temperature and used for new hot metal desulfurization treatment, thereby increasing the utilization efficiency of CaO and reducing the amount of desulfurization slag discharged. Techniques for reducing are disclosed.
特許文献２には、硫黄を含有するスラグを溶媒に浸漬し、溶媒中に二酸化炭素を吹き込んで溶媒をｐＨ４〜１０に調整することで、スラグに含まれる硫黄を溶媒中に抽出し、スラグの硫黄含有量を低減させる技術が開示されている。
In
しかしながら、上記従来技術には以下の問題点がある。 However, the above prior art has the following problems.
即ち、特許文献１では、高温でリサイクルされる脱硫スラグ中には硫黄が含有されており、リサイクル回数を重ねることによって脱硫スラグ中の硫黄濃度が上昇して脱硫能が低下するので、リサイクルできる量には制約がある。また、脱硫スラグの発生量は少なくなるものの、最終的には脱硫スラグを処理する必要がある。 That is, in Patent Document 1, sulfur is contained in desulfurized slag that is recycled at a high temperature, and the sulfur concentration in the desulfurized slag increases and the desulfurization ability decreases as the number of recycling is repeated. There are limitations. Further, although the amount of desulfurized slag generated is reduced, it is finally necessary to treat the desulfurized slag.
特許文献２は湿式処理であり、湿式処理の場合、処理に必要な薬品が高価であるのみならず、大掛かりな処理設備が必要となり、設備費及び運転費ともに高価となる。
本発明は上記事情に鑑みてなされたもので、その目的とするところは、溶銑の脱硫処理で発生する脱硫スラグに含有される硫黄を効率的に除去することによって、製銑工程及び製鋼工程では、硫黄濃度の低下した脱硫スラグを硫黄の影響を受けることなくＣａＯ源として有効にリサイクル活用することのできる、脱硫スラグからの硫黄の除去方法を提供することである。 The present invention has been made in view of the above circumstances, and the object of the present invention is to efficiently remove sulfur contained in the desulfurization slag generated in the desulfurization treatment of the hot metal, thereby making the steelmaking process and the steelmaking process effective. An object of the present invention is to provide a method for removing sulfur from desulfurized slag, in which desulfurized slag having a reduced sulfur concentration can be effectively recycled as a CaO source without being affected by sulfur.
上記課題を解決するための本発明の要旨は以下のとおりである。
［１］溶銑の脱硫処理において発生し、その後の散水冷却によって常温まで冷却された、硫黄を含有する脱硫スラグを、雰囲気温度が１２５０〜１５００℃の範囲に調整された大気雰囲気中に曝し、前記脱硫スラグ中の硫黄をＳＯｘとして雰囲気の気相側に除去する第１の工程と、前記第１の工程において気相側に除去されたＳＯｘを含有する排ガスを脱硫処理する第２の工程と、前記第１の工程によって硫黄含有量が低下した脱硫スラグを製銑工程または製鋼工程でのＣａＯ源としてリサイクルする第３の工程と、を有することを特徴とする、脱硫スラグからの硫黄の除去方法。
［２］前記第３の工程における処理後の脱硫スラグのリサイクル先が、鉄鉱石の焼結工程または高炉での溶銑製造工程であることを特徴とする、上記［１］に記載の脱硫スラグからの硫黄の除去方法。
［３］前記第３の工程における処理後の脱硫スラグのリサイクル先が、製鋼精錬工程における溶銑の脱硫処理、予備脱燐処理、脱炭精錬処理の何れかであることを特徴とする、上記［１］に記載の脱硫スラグからの硫黄の除去方法。
［４］前記第１の工程に供する脱硫スラグから事前に金属鉄を分離することを特徴とする、上記［１］ないし上記［３］の何れか１項に記載の脱硫スラグからの硫黄の除去方法。
The gist of the present invention for solving the above problems is as follows.
[1] The sulfur-containing desulfurization slag generated in the hot metal desulfurization treatment and then cooled to room temperature by water spray cooling is exposed to an air atmosphere adjusted to an atmosphere temperature of 1250 to 1500 ° C., and A first step of removing sulfur in the desulfurization slag as SOx on the gas phase side of the atmosphere; a second step of desulfurizing the exhaust gas containing SOx removed on the gas phase side in the first step; And a third step of recycling the desulfurized slag having a reduced sulfur content in the first step as a CaO source in the ironmaking step or the steelmaking step, and a method for removing sulfur from the desulfurized slag .
[2] From the desulfurization slag according to the above [1], the recycling destination of the desulfurization slag after the treatment in the third step is an iron ore sintering step or a hot metal production step in a blast furnace To remove sulfur in water.
[3] The recycling destination of the desulfurization slag after the treatment in the third step is any one of hot metal desulfurization treatment, preliminary dephosphorization treatment, and decarburization refining treatment in the steelmaking refining step, [1] The method for removing sulfur from the desulfurized slag according to [1].
[4] The removal of sulfur from the desulfurized slag according to any one of [1] to [3] above, wherein metallic iron is separated in advance from the desulfurized slag used in the first step. Method.
本発明によれば、溶銑の脱硫処理で発生する脱硫スラグを製銑工程または製鋼工程へリサイクルするにあたり、脱硫スラグを散水冷却によって常温まで強制的に冷却し、この急冷した脱硫スラグを１２５０〜１５００℃の雰囲気温度の大気雰囲気中に曝すので、脱硫スラグ中の硫黄の大半を大気雰囲気の気相側へＳＯｘとして除去することができる。そして、硫黄含有量の低下したスラグを製銑工程または製鋼工程におけるＣａＯ源としてリサイクルするので、製銑工程及び製鋼工程では、硫黄の影響を受けることなくＣａＯ源として再利用することができる。 According to the present invention, when recycling the desulfurization slag generated in the hot metal desulfurization process to the steelmaking process or the steelmaking process, the desulfurization slag is forcibly cooled to room temperature by water spraying, and the rapidly cooled desulfurization slag is 1250-1500. Since it is exposed to an air atmosphere at an atmospheric temperature of ° C., most of the sulfur in the desulfurized slag can be removed as SOx to the gas phase side of the air atmosphere. And since the slag with which sulfur content fell was recycled as a CaO source in a steelmaking process or a steelmaking process, in a steelmaking process and a steelmaking process, it can reuse as a CaO source, without receiving the influence of sulfur.
製銑工程へのリサイクルでは、鉄鉱石の焼結工程または高炉へのリサイクルによって高炉スラグの発生量が増加するが、高炉スラグは、高炉スラグを微粉末状にしてセメントの混和材として使用することによって、高炉スラグ中のＣａＯ分などがセメントと同様のポゾラン反応を起こし、セメントの強度を発現させる。従来、セメント原料のＣａＯ分は炭酸カルシウム（ＣａＣＯ3）を焼成して製造しており、この焼成時に熱エネルギーを必要とするのみならずＣＯ2ガスも発生するが、高炉スラグ微粉末をセメントに混ぜて高炉スラグセメント（「高炉セメント」と呼ぶ）とした場合には、高炉スラグ微粉末／普通ポルトランドセメントの混合比率に応じて、焼成エネルギー及びＣＯ2ガスの発生量を低減可能となる。また、製鋼工程へのリサイクルでは、スラグをＣａＯ源としてリサイクルすることで、生石灰（ＣａＯ）の使用量を低減することができ、製鋼スラグの発生量を大幅に低減することができる。また、脱硫スラグを製銑工程や製鋼工程にリサイクルすることで、脱硫スラグ中の鉄分をも鉄資源として有効活用することが可能となる。 In recycling to the ironmaking process, the amount of blast furnace slag generated increases due to the iron ore sintering process or recycling to the blast furnace, but the blast furnace slag should be used as a cement admixture in the form of fine powder. As a result, the CaO content in the blast furnace slag causes a pozzolanic reaction similar to that of the cement and develops the strength of the cement. Conventionally, the CaO content of the cement raw material has been manufactured by calcining calcium carbonate (CaCO 3 ), and this calcining requires not only thermal energy but also generates CO 2 gas. When mixed into a blast furnace slag cement (referred to as “blast furnace cement”), the firing energy and the amount of CO 2 gas generated can be reduced according to the mixing ratio of blast furnace slag fine powder / ordinary Portland cement. Moreover, in recycling to a steelmaking process, the amount of quicklime (CaO) used can be reduced by recycling slag as a CaO source, and the generated amount of steelmaking slag can be greatly reduced. Moreover, by recycling the desulfurized slag to the iron making process and the steel making process, it becomes possible to effectively use the iron content in the desulfurized slag as an iron resource.
以下、本発明を詳細に説明する。 Hereinafter, the present invention will be described in detail.
本発明者らは、ＣａＯ単体、或いは、ＣａＯにＣａＦ2またはＡｌ2Ｏ3をＣａＯの滓化促進剤として添加したＣａＯ−ＣａＦ2やＣａＯ−Ａｌ2Ｏ3を脱硫剤として用いた溶銑の脱硫処理で発生する脱硫スラグを、ＣａＯ源として製銑工程または製鋼工程でリサイクル使用する際に、リサイクルする前に脱硫スラグから硫黄を除去する方法を検討した。 The present inventors have made use of CaO alone or hot metal desulfurization using CaO—CaF 2 or CaO—Al 2 O 3 in which CaF 2 or Al 2 O 3 is added to CaO as a CaO hatching accelerator. When the desulfurization slag generated in the treatment was recycled as a CaO source in the ironmaking process or the steelmaking process, a method for removing sulfur from the desulfurization slag before recycling was examined.
先ず、製鉄所内での脱硫スラグの冷却・粉砕処理プロセスにおいて、脱硫スラグから試料を採取し、脱硫スラグ中の硫黄の化合物形態についてＸ線回折を用いて調査した。その結果、溶銑の脱硫処理によって発生し、溶銑上から排出した後の高温の脱硫スラグを常温まで散水冷却により強制的に急冷した脱硫スラグ中の硫黄化合物は大部分がＣａＳの化合物形態であることがわかった。ＣａＳは脱硫反応の生成物であり、脱硫スラグを散水により急冷することで、ＣａＳが、ＣａＳＯ3やＣａＳＯ4などに酸化することなく、ＣａＳとして脱硫スラグ中に残存したと考えられる。上記の常温とは２００℃以下、好ましくは１００℃以下である。 First, in the process of cooling and pulverizing desulfurized slag in the steelworks, a sample was taken from the desulfurized slag, and the compound form of sulfur in the desulfurized slag was investigated using X-ray diffraction. As a result, most of the sulfur compounds in the desulfurized slag generated by the desulfurization treatment of the hot metal and forcibly quenched by high-temperature desulfurization slag after being discharged from the hot metal to the room temperature are CaS compound forms. I understood. CaS is a product of the desulfurization reaction, and it is considered that CaS remained in the desulfurized slag as CaS without being oxidized into CaSO 3 or CaSO 4 by rapidly cooling the desulfurized slag with water spray. Said normal temperature is 200 degrees C or less, Preferably it is 100 degrees C or less.
次に、ＣａＳからの硫黄の除去について熱力学的な検討並びに小型実験を行った。その結果、大気雰囲気での加熱処理つまり高温の大気雰囲気中に曝して脱硫スラグを酸化することで、ＣａＳ中の硫黄が気体のＳＯｘになり、脱硫スラグ中の硫黄を気相側へ除去することが可能であること、また、雰囲気温度が高くなるほど、脱硫スラグからの脱硫率が高くなることがわかった。具体的には、雰囲気温度を１２５０℃以上とすることで、７０％以上の脱硫率が得られることがわかった。このときの反応は、２ＣａＳ＋３Ｏ2＝２ＣａＯ＋２ＳＯ2であると考えられる。ここで、脱硫率（％）とは、加熱処理前の脱硫スラグの硫黄濃度（質量％）と加熱処理後の脱硫スラグの硫黄濃度（質量％）との差分を、加熱処理前の脱硫スラグの硫黄濃度（質量％）に対して百分率で表示した値である。 Next, a thermodynamic study and a small experiment were conducted on the removal of sulfur from CaS. As a result, heat treatment in an air atmosphere, that is, exposure to high-temperature air atmosphere to oxidize desulfurized slag, sulfur in CaS becomes gaseous SOx, and sulfur in desulfurized slag is removed to the gas phase side. It was found that the desulfurization rate from the desulfurized slag increases as the atmospheric temperature increases. Specifically, it was found that a desulfurization rate of 70% or higher can be obtained by setting the ambient temperature to 1250 ° C. or higher. The reaction at this time is considered to be 2CaS + 3O 2 = 2CaO + 2SO 2 . Here, the desulfurization rate (%) is the difference between the sulfur concentration (mass%) of the desulfurized slag before heat treatment and the sulfur concentration (mass%) of the desulfurized slag after heat treatment. It is a value expressed as a percentage with respect to the sulfur concentration (mass%).
更に、本発明者らは、耐火物が施工された大型の加熱炉を用いて加熱試験を行った。その結果、雰囲気温度が１５００℃を超えると、炉壁耐火物の損傷が極めて激しくなることや、脱硫スラグの炉壁への溶融付着が生じるなどの操業上の問題が顕在化した。つまり、最適な雰囲気温度として、１２５０〜１５００℃であることが確認できた。 Furthermore, the present inventors performed a heating test using a large-sized heating furnace on which a refractory was constructed. As a result, when the ambient temperature exceeded 1500 ° C., operational problems such as the extremely severe damage to the furnace wall refractories and the melting adhesion of desulfurized slag to the furnace wall became apparent. That is, it was confirmed that the optimum atmospheric temperature was 1250 to 1500 ° C.
脱硫スラグに対して大気雰囲気での加熱処理、つまり、脱硫スラグからの硫黄の除去処理を行う反応容器としては、大気雰囲気下で脱硫スラグに熱を与えることができるものであればどのようなものでもよく、具体的には、ロータリーキルン、ＲＨＦ、流動層、電気炉などが挙げられる。また、加熱方式としては、ＬＰＧバーナーやＬＮＧバーナーなどの燃焼バーナーによる熱付与や、黒鉛電極を用いた加熱、プラズマなどを用いることができる。 Any reaction vessel that heats the desulfurized slag in an air atmosphere, that is, removes sulfur from the desulfurized slag, as long as it can apply heat to the desulfurized slag in the air atmosphere. However, specific examples include a rotary kiln, RHF, fluidized bed, and electric furnace. In addition, as a heating method, heat application by a combustion burner such as an LPG burner or an LNG burner, heating using a graphite electrode, plasma, or the like can be used.
この加熱処理によって硫黄含有量が低下した脱硫スラグのリサイクル方法としては、鉄鉱石の焼結工程におけるＣａＯ源（造滓剤）として利用し、その後、高炉での溶銑製造工程で装入原料として使用する方法以外に、高炉での溶銑製造工程でのＣａＯ系の造滓剤として直接使用する方法、または、高炉溶銑の予備脱燐処理や脱硫処理におけるＣａＯ系フラックスとして使用する方法、或いは、転炉での溶銑の脱炭精錬工程における造滓剤として使用する方法などが、好適な例として挙げられる。これ以外の工程であっても、製鉄所における製銑工程及び製鋼工程の生石灰を使用している工程である限り、生石灰の代替として使用可能である。尚、発生する脱硫スラグの全量を本発明の硫黄除去処理に供しても構わないが、溶銑の脱硫処理において発生した脱硫スラグを、再度、溶銑の脱硫処理に使用することは、省資源の観点からも有効である。つまり、脱硫スラグ中の硫黄濃度がリサイクルによって高くなり、脱硫剤としての効用がなくなるまでは、溶銑脱硫処理工程へのリサイクルを行い、脱硫スラグ中の硫黄濃度が高くなり脱硫剤としての効用がなくなった時点で、本発明を適用することが好ましい。 As a method of recycling desulfurized slag whose sulfur content has been reduced by this heat treatment, it is used as a CaO source (slagging agent) in the iron ore sintering process, and then used as a charging raw material in the hot metal production process in a blast furnace In addition to the method to use, a method of directly using as a CaO-based iron making agent in the hot metal production process in the blast furnace, a method of using as a CaO-based flux in the preliminary dephosphorization treatment or desulfurization treatment of the blast furnace hot metal, or a converter A suitable example is a method of using it as a slag-forming agent in the decarburization and refining process of hot metal in the above. Even if it is a process other than this, as long as it is the process which uses the quicklime of the iron making process and steelmaking process in an ironworks, it can be used as a substitute for quicklime. Although the total amount of desulfurized slag generated may be subjected to the sulfur removal treatment of the present invention, the use of the desulfurized slag generated in the hot metal desulfurization treatment again in the hot metal desulfurization treatment is a viewpoint of saving resources. Is also effective. In other words, until the sulfur concentration in the desulfurization slag becomes high due to recycling and the utility as a desulfurization agent ceases, the sulfur concentration in the desulfurization slag becomes high and the utility as a desulfurization agent is lost. At this point, it is preferable to apply the present invention.
また、本発明の硫黄除去処理に供する脱硫スラグには金属鉄が含まれていることが多く、この金属鉄の大部分は、硫黄除去処理を経た後には酸化鉄となる。酸化鉄を含んだスラグを製銑工程や製鋼工程にリサイクルした場合には、酸化鉄は還元されて鉄資源となり得るものの、酸化鉄の還元エネルギーが必要となる。そこで、本発明の硫黄除去処理に供する前に脱硫スラグから金属鉄を取り除くことが好ましい。金属鉄の分離には、例えば磁力を用いた分離や、鉄とスラグとの比重差を利用した遠心気流分離など、スラグの形状や処理量に応じて適切なプロセスを選択すればよい。 Moreover, the desulfurized slag used for the sulfur removal treatment of the present invention often contains metallic iron, and most of the metallic iron becomes iron oxide after the sulfur removal treatment. When slag containing iron oxide is recycled to the iron making process or the steel making process, the iron oxide can be reduced to become an iron resource, but the reduction energy of iron oxide is required. Therefore, it is preferable to remove metallic iron from the desulfurized slag before being subjected to the sulfur removal treatment of the present invention. For separation of metallic iron, an appropriate process may be selected according to the shape and processing amount of slag, such as separation using magnetic force or centrifugal airflow separation using the difference in specific gravity between iron and slag.
気相側へ除去されたＳＯｘを含有する排ガスに対して脱硫処理（排煙脱硫処理）を施し、排ガス中のＳＯｘの大気への放散を防止する。排煙脱硫処理方法としては、一般に広く適用されている石灰石膏法や、水酸化マグネシウム法、或いは乾式の活性コークス法など様々な方式を採用することができる。排煙脱硫処理方式は、硫黄除去処理によって発生する排ガスの流量や副生物の処置、処理コスト、設備コストなどを総合的に判断して最適な方式を選択すればよい。 The exhaust gas containing SOx removed to the gas phase side is subjected to a desulfurization process (a flue gas desulfurization process) to prevent emission of SOx in the exhaust gas to the atmosphere. As the flue gas desulfurization treatment method, various methods such as a lime gypsum method, a magnesium hydroxide method, and a dry activated coke method which are generally widely used can be employed. For the flue gas desulfurization treatment method, an optimum method may be selected by comprehensively judging the flow rate of exhaust gas generated by the sulfur removal treatment, the treatment of by-products, treatment costs, equipment costs, and the like.
以上説明したように、本発明によれば、溶銑の脱硫処理で発生する脱硫スラグを製銑工程または製鋼工程へリサイクルするにあたり、脱硫スラグを散水冷却によって常温まで強制的に冷却し、この脱硫スラグを１２５０〜１５００℃の雰囲気温度の大気雰囲気中に曝すので、脱硫スラグ中の硫黄を気体のＳＯｘとして気相へ除去することができ、硫黄含有量の少ない脱硫スラグをＣａＯ源として有効活用することが実現される。これにより、脱硫スラグ自体の発生量が減少して脱硫スラグの処理コストを削減することができるとともに、脱硫スラグを製鉄所外で有効利用したときの黄水発生などのリスクも回避することができる。 As described above, according to the present invention, when the desulfurization slag generated in the hot metal desulfurization process is recycled to the ironmaking process or the steelmaking process, the desulfurization slag is forcibly cooled to room temperature by sprinkling cooling. Is exposed to an atmospheric atmosphere at an ambient temperature of 1250 to 1500 ° C., sulfur in the desulfurized slag can be removed to the gas phase as gaseous SOx, and desulfurized slag with a low sulfur content can be effectively utilized as a CaO source. Is realized. Thereby, the generation amount of desulfurization slag itself can be reduced and the processing cost of the desulfurization slag can be reduced, and risks such as yellow water generation when the desulfurization slag is effectively used outside the steelworks can be avoided. .
高炉から出銑された高炉溶銑をトピードカーで受銑し、トピードカーに収容された高炉溶銑に脱珪処理及び予備脱燐処理を施し、その後、高炉溶銑を溶銑鍋に移し替え、溶銑鍋内の高炉溶銑に機械攪拌式脱硫装置により脱硫処理を施し、この脱硫処理終了後の高炉溶銑を転炉に装入して転炉にて脱炭精錬を施し、かくして、高炉溶銑から溶鋼を溶製する製銑−製鋼工程において本発明を適用した。高炉での出銑から転炉脱炭精錬終了までの高炉溶銑及び溶製される溶鋼の化学成分の例を表１に示す。 The blast furnace hot metal discharged from the blast furnace is received by a topped car, the blast furnace hot metal accommodated in the topped car is subjected to desiliconization treatment and preliminary dephosphorization treatment, and then the blast furnace hot metal is transferred to the hot metal ladle and the blast furnace in the hot metal ladle. The hot metal is desulfurized by a mechanical stirring desulfurization device, the blast furnace hot metal after this desulfurization treatment is charged into the converter, and decarburization refining is performed in the converter, thus producing molten steel from the blast furnace hot metal. The present invention was applied in the steelmaking process. Table 1 shows examples of chemical components of the blast furnace hot metal and the molten steel produced from the blast furnace tapping to the end of converter decarburization refining.
表１に示すように、脱硫処理前の高炉溶銑には０．０３質量％程度の硫黄が含有されており、溶銑脱硫工程において脱硫剤としてＣａＯ源（生石灰）を添加し攪拌処理をすることで０．００２質量％まで脱硫される。この時発生する脱硫スラグをスラグ処理場に搬送し、散水冷却して常温まで冷却した。この脱硫スラグに対して本発明を適用する試験を行った。冷却後の脱硫スラグの代表組成を表２に示す。 As shown in Table 1, the blast furnace hot metal before the desulfurization treatment contains about 0.03% by mass of sulfur. By adding a CaO source (quick lime) as a desulfurization agent in the hot metal desulfurization step, stirring treatment is performed. Desulfurized to 0.002% by mass. The desulfurized slag generated at this time was conveyed to a slag treatment plant, cooled with water and cooled to room temperature. The test which applies this invention with respect to this desulfurization slag was done. Table 2 shows typical compositions of desulfurized slag after cooling.
散水冷却した５０トンの脱硫スラグを、加熱バーナーを備えたロータリーキルンに装入し、バーナーによって脱硫スラグを加熱して脱硫スラグからの硫黄除去処理を実施した。脱硫スラグ中の硫黄化合物の形態は、硫黄除去処理前に脱硫スラグから試料を採取し、Ｘ線回折装置を用い、硫黄化合物の大部分がＣａＳであることを確認した。炉内雰囲気の温度は加熱バーナーの出力を調整することで制御し、炉内雰囲気は大気雰囲気とした。排ガス側には排煙脱硫設備を設け、排ガス中のＳＯｘを無害化処理した。表３に、試験条件並びに試験結果を示し、また、図１に硫黄除去処理時の雰囲気温度と脱硫スラグからの脱硫率との関係を示す。 50 tons of desulfurized slag cooled with water spray was charged into a rotary kiln equipped with a heating burner, and the desulfurized slag was heated by the burner to remove sulfur from the desulfurized slag. Regarding the form of the sulfur compound in the desulfurized slag, a sample was taken from the desulfurized slag before the sulfur removal treatment, and an X-ray diffractometer was used to confirm that most of the sulfur compound was CaS. The temperature of the furnace atmosphere was controlled by adjusting the output of the heating burner, and the furnace atmosphere was an air atmosphere. A flue gas desulfurization facility was provided on the exhaust gas side to detoxify SOx in the exhaust gas. Table 3 shows the test conditions and test results, and FIG. 1 shows the relationship between the atmospheric temperature during the sulfur removal treatment and the desulfurization rate from the desulfurization slag.
図１に示すように、硫黄除去処理時の雰囲気温度（加熱温度）を１２５０℃以上とすることで、７０％以上の脱硫率を得ることができた。一方、比較例４及び比較例５に示すとおり、雰囲気温度が１５００℃を超える場合には、脱硫スラグの脱硫率には大きな差がないものの、炉体耐火物の溶融や、溶融した脱硫スラグの炉内付着が激しいことが認められた。尚、本発明例１及び本発明例２に示すように、雰囲気温度が１４５０〜１５００℃においても、若干の炉体耐火物の溶融や、溶融した脱硫スラグの炉内付着が認められたが、根本的に操業を阻害するものではなかった。 As shown in FIG. 1, a desulfurization rate of 70% or more could be obtained by setting the atmospheric temperature (heating temperature) during the sulfur removal treatment to 1250 ° C. or higher. On the other hand, as shown in Comparative Example 4 and Comparative Example 5, when the ambient temperature exceeds 1500 ° C., the desulfurization rate of the desulfurized slag is not greatly different, but the melting of the furnace refractory or the molten desulfurized slag It was observed that adhesion in the furnace was severe. In addition, as shown in Invention Example 1 and Invention Example 2, even when the ambient temperature was 1450 to 1500 ° C., some melting of the furnace body refractory and adhesion of the molten desulfurized slag in the furnace were observed, It did not fundamentally hinder operations.
本発明例１〜６の硫黄除去処理後の脱硫スラグを鉄鉱石の焼結工程における造滓剤用のＣａＯ源として使用し、製造した焼結鉱を鉄源として高炉に装入し、高炉溶銑を製造したが、何ら問題はなかった。また、リサイクルを行った際の高炉スラグを用いて高炉スラグセメントを製造したが、JIS A 6206「コンクリート用高炉スラグ微粉末」の品質規格を満足しており、また、JIS R 5211 「高炉セメント」の強度などの特性も従来と同等で何ら問題はなく、従来と同様にセメント製造の省エネルギー化が可能となった。 The desulfurization slag after the sulfur removal treatment of Invention Examples 1 to 6 was used as a CaO source for a slagging agent in the iron ore sintering step, and the produced sintered ore was charged into a blast furnace as an iron source, Was manufactured, but there was no problem. In addition, blast furnace slag cement was manufactured using the blast furnace slag that was recycled, but it satisfied the quality standard of JIS A 6206 “Blast furnace slag fine powder for concrete” and JIS R 5211 “Blast furnace cement” The strength and other properties are the same as in the past, and there are no problems.
また、本発明例１〜６の硫黄除去処理後の脱硫スラグを製鋼工程における溶銑の脱硫処理、予備脱燐処理、脱炭精錬処理用のＣａＯ源としても用いたが、何ら問題なく精錬操業を行うことができた。 Moreover, although the desulfurization slag after the sulfur removal treatment of Invention Examples 1 to 6 was used as a CaO source for hot metal desulfurization treatment, preliminary dephosphorization treatment, and decarburization refining treatment in the steelmaking process, the refining operation can be performed without any problem. Could be done.
更に、事前に磁気分離により脱硫スラグから金属鉄を取り除いてから、硫黄除去処理を行っても、適正な条件であれば脱硫率は８０％以上を満足し、また、事前に取り除いた金属鉄は、鉄資源として製銑工程や製鋼工程で還元エネルギーを消費することなく活用することができた。 Furthermore, even after removing the metallic iron from the desulfurization slag by magnetic separation in advance and performing the sulfur removal treatment, the desulfurization rate satisfies 80% or more under appropriate conditions, and the metallic iron removed in advance is As a steel resource, it could be utilized without consuming reducing energy in the ironmaking process and steelmaking process.
一方、溶銑の脱硫処理で発生した脱硫スラグを本発明の硫黄除去処理を施すことなくそのまま焼結鉱のＣａＯ源としてリサイクルした場合には、焼結での排ガス中ＳＯｘ濃度が規制値を超えてしまうために、焼結設備に排煙脱硫処理を設置しなければ操業が成り立たなかった。また、脱硫スラグを本発明の硫黄除去処理を施すことなくそのまま高炉へリサイクルした場合には、高炉スラグの硫黄濃度が上昇し、高炉スラグセメントの製造条件を満足することができなかった。更に、脱硫スラグを本発明の硫黄除去処理を施すことなくそのまま製鋼工程の予備脱燐処理や脱炭精錬処理にＣａＯ源としてリサイクルした場合には、溶銑や溶鋼の硫黄濃度が上昇し、操業阻害を引き起こした。溶銑の脱硫処理にＣａＯ源としてリサイクルした場合には、或る一定の量まではリサイクル可能であったものの、脱硫スラグの発生全量を製鉄所内でリサイクルすることは不可能であった。 On the other hand, when the desulfurization slag generated in the hot metal desulfurization treatment is recycled as it is as a CaO source of sintered ore without performing the sulfur removal treatment of the present invention, the SOx concentration in the exhaust gas during sintering exceeds the regulation value. For this reason, the operation could not be completed unless the flue gas desulfurization treatment was installed in the sintering facility. In addition, when the desulfurized slag was recycled to the blast furnace as it was without performing the sulfur removal treatment of the present invention, the sulfur concentration of the blast furnace slag increased, and the production conditions for the blast furnace slag cement could not be satisfied. Furthermore, if the desulfurized slag is recycled as a CaO source for the preliminary dephosphorization process or decarburization refining process of the steelmaking process without performing the sulfur removal process of the present invention, the sulfur concentration of the hot metal or the molten steel increases and operation is inhibited. Caused. When the hot metal desulfurization treatment was recycled as a CaO source, it was possible to recycle up to a certain amount, but it was impossible to recycle the entire amount of desulfurization slag generated in the steelworks.
Claims (4)
前記第１の工程において気相側に除去されたＳＯｘを含有する排ガスを脱硫処理する第２の工程と、
前記第１の工程によって硫黄含有量が低下した脱硫スラグを製銑工程または製鋼工程でのＣａＯ源としてリサイクルする第３の工程と、
を有することを特徴とする、脱硫スラグからの硫黄の除去方法。 It is generated in the hot metal desulfurization process, and after being discharged from the hot metal, it is forcibly cooled to a temperature of 200 ° C. or less by sprinkling cooling, and by this cooling, the CaSO of CaS in the desulfurized slag generated by the hot metal desulfurization reaction An atmosphere in which the desulfurization slag is prevented from being oxidized during the cooling process to 3 and CaSO 4 , and the desulfurization slag containing CaS, which is the product of the desulfurization reaction, is mainly contained in the sulfur compound contained in the atmosphere at a temperature of 1250 to 1500 ° C. A first step of exposing to the atmosphere and removing sulfur in the desulfurized slag as SOx to the gas phase side of the atmosphere;
A second step of desulfurizing the exhaust gas containing SOx removed on the gas phase side in the first step;
A third step of recycling the desulfurized slag having a reduced sulfur content in the first step as a CaO source in the iron making step or the steel making step;
A method for removing sulfur from desulfurized slag, comprising:
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