JP4304110B2 - Detoxification method for chromium-containing steel slag - Google Patents
Detoxification method for chromium-containing steel slag Download PDFInfo
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- 239000011651 chromium Substances 0.000 title claims description 162
- 239000002893 slag Substances 0.000 title claims description 158
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 title claims description 51
- 229910052804 chromium Inorganic materials 0.000 title claims description 51
- 229910000831 Steel Inorganic materials 0.000 title claims description 21
- 239000010959 steel Substances 0.000 title claims description 21
- 238000000034 method Methods 0.000 title description 25
- 238000001784 detoxification Methods 0.000 title description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 88
- 238000010828 elution Methods 0.000 claims description 50
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 43
- AMWRITDGCCNYAT-UHFFFAOYSA-L hydroxy(oxo)manganese;manganese Chemical compound [Mn].O[Mn]=O.O[Mn]=O AMWRITDGCCNYAT-UHFFFAOYSA-L 0.000 claims description 40
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 34
- 239000000203 mixture Substances 0.000 claims description 25
- 238000007670 refining Methods 0.000 claims description 25
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 20
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 claims description 17
- 229910000423 chromium oxide Inorganic materials 0.000 claims description 17
- 239000000126 substance Substances 0.000 claims description 12
- 239000010935 stainless steel Substances 0.000 claims description 8
- 229910001220 stainless steel Inorganic materials 0.000 claims description 8
- 238000003723 Smelting Methods 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 3
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 30
- 239000000395 magnesium oxide Substances 0.000 description 21
- 239000000292 calcium oxide Substances 0.000 description 15
- 235000012255 calcium oxide Nutrition 0.000 description 15
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 13
- 239000000463 material Substances 0.000 description 12
- 239000011572 manganese Substances 0.000 description 8
- 230000009467 reduction Effects 0.000 description 8
- 238000005261 decarburization Methods 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 150000001875 compounds Chemical class 0.000 description 6
- 229910052742 iron Inorganic materials 0.000 description 6
- 229910052717 sulfur Inorganic materials 0.000 description 6
- 229910017082 Fe-Si Inorganic materials 0.000 description 5
- 229910017133 Fe—Si Inorganic materials 0.000 description 5
- 238000007664 blowing Methods 0.000 description 5
- 239000000428 dust Substances 0.000 description 5
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000004090 dissolution Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 239000002689 soil Substances 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 3
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 239000011261 inert gas Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 239000004568 cement Substances 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 238000007922 dissolution test Methods 0.000 description 2
- 238000004453 electron probe microanalysis Methods 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 238000010587 phase diagram Methods 0.000 description 2
- 229910052596 spinel Inorganic materials 0.000 description 2
- 239000011029 spinel Substances 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 230000001502 supplementing effect Effects 0.000 description 2
- 229910014458 Ca-Si Inorganic materials 0.000 description 1
- 229910017060 Fe Cr Inorganic materials 0.000 description 1
- 229910002544 Fe-Cr Inorganic materials 0.000 description 1
- 229910002551 Fe-Mn Inorganic materials 0.000 description 1
- 206010037660 Pyrexia Diseases 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- UPHIPHFJVNKLMR-UHFFFAOYSA-N chromium iron Chemical compound [Cr].[Fe] UPHIPHFJVNKLMR-UHFFFAOYSA-N 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 229910000514 dolomite Inorganic materials 0.000 description 1
- 239000010459 dolomite Substances 0.000 description 1
- -1 electric furnaces Inorganic materials 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000002407 reforming Methods 0.000 description 1
- 238000010405 reoxidation reaction Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 238000003911 water pollution Methods 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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- Carbon Steel Or Casting Steel Manufacturing (AREA)
- Processing Of Solid Wastes (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
- Treatment Of Steel In Its Molten State (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Description
本発明は、含クロム鉄鋼スラグの無害化方法、特に、含クロム鉄鋼スラグからの６価Ｃｒの溶出を抑制して無害化し、路盤材、セメント材、海洋用途等の資源として利用を図ることのできるスラグ組成とするステンレス鋼の精錬方法に関する。 The present invention is a detoxification method for chromium-containing steel slag, in particular, detoxification by suppressing elution of hexavalent Cr from chromium-containing steel slag, and can be used as a resource for roadbed materials, cement materials, marine applications, etc. The present invention relates to a method for refining stainless steel having a slag composition.
含クロム鉄鋼スラグは、原料を溶解する工程あるいは脱炭、生成酸化物の還元、脱硫等の精錬工程において不可避的に発生し、数％のクロム酸化物を含有している。そのため、クロム酸化物の存在状態によっては、スラグを路盤材や海洋用途等へ再利用した際に、水や土壌等へ有害な６価Ｃｒが溶出する場合があり、有効利用を困難にしている。水質汚濁防止法の排水基準では６価Ｃｒ溶出量≦０．５ｍｇ／ｌ、また土壌環境基準については６価Ｃｒ溶出量≦０．０５ｍｇ／ｌ（土壌が地下水から離れている場合には０．１５ｍｇ／ｌ）と定められている。 Chromium-containing steel slag is inevitably generated in refining processes such as melting raw materials or decarburization, reduction of generated oxides, desulfurization and the like, and contains several% of chromium oxide. Therefore, depending on the state of chromium oxide, when slag is reused for roadbed materials or marine applications, harmful hexavalent Cr may be eluted into water, soil, etc., making effective use difficult. . Elution amount of hexavalent Cr ≦ 0.5 mg / l in the drainage standard of the Water Pollution Control Law, and the elution amount of hexavalent Cr ≦ 0.05 mg / l in the soil environment standard (in the case where the soil is separated from the groundwater, 0. 15 mg / l).
含クロム鉄鋼スラグからの６価クロムの溶出防止方法として、特許文献１において、アルミ灰およびマグネシア系物質を受滓鍋に敷き詰めておき、溶融状態にあるスラグを受滓鍋に排滓する方法が提案されている。この方法においては、ＭｇＯ・Ａｌ2Ｏ3という組成のスピネルを形成させ、その中へ酸化クロムを固溶させることにより安定化させることでクロムの再酸化すなわち６価クロム生成を防止している。しかしながら、この方法では、アルミ灰やマグネシア物質を添加した後にスピネルを形成させ、そこに酸化クロムを固溶させるため、クロムが安定化されるのに時間がかかり、溶融状態での混合が不十分な場合には６価クロムが溶出してしまうという問題点があった。
As a method for preventing elution of hexavalent chromium from chromium-containing steel slag,
また、ステンレス鋼の脱炭精錬後、スラグ中のＣｒを溶鋼中へ回収する還元処理を経た溶融状態のスラグに対し、ＦｅＳなどの−２価のＳ化合物を添加し、不活性ガスの吹き込み攪拌によりスラグ中Ｓ濃度を０．２０質量％以上として６価Ｃｒの溶出を防止する方法が開示されている（特許文献２）。この方法は、溶融スラグに添加剤を均質に混合するために不活性ガスの吹き込みを行いクロム酸化物の安定化を図るもので、６価Ｃｒの溶出を防止する方法としては有効であるが、還元処理終了後に不活性ガスの吹き込みやスラグの粘度を低下させるための添加剤を使用するといった操作が必要となり、経済性の面で問題があった。 In addition, after decarburization and refining of stainless steel, -2 valent S compound such as FeS is added to the molten slag that has undergone a reduction treatment that recovers Cr in the slag into molten steel, and an inert gas is blown and stirred. Discloses a method for preventing elution of hexavalent Cr by setting the S concentration in the slag to 0.20 mass% or more (Patent Document 2). This method is to stabilize the chromium oxide by blowing an inert gas in order to uniformly mix the additive into the molten slag, and is effective as a method for preventing the elution of hexavalent Cr. After completion of the reduction treatment, an operation such as blowing an inert gas or using an additive for reducing the viscosity of the slag is necessary, which is problematic in terms of economy.
また、クロム酸化物含有物質からの６価Ｃｒ溶出防止方法として、高炉徐冷スラグ冷却水を散水する方法、高炉徐冷スラグ冷却水に浸漬する方法、高炉徐冷スラグと混合し水蒸気を吹き込む方法も提案されている（特許文献３）。さらに、この方法の改善方法として、クロム酸化物含有物質の上に高炉スラグ等の硫黄含有スラグを載せて散水する方法（特許文献４）やクロム酸化物含有物質に水蒸気を吹き込んだ後に、高炉スラグ溶出水を散水したり、高炉スラグ溶出水に浸漬する方法（特許文献５）が提案されている。 In addition, as a method for preventing hexavalent Cr elution from a chromium oxide-containing material, a method of spraying blast furnace slow-cooled slag cooling water, a method of immersing in blast furnace slow-cooled slag cooling water, a method of mixing with blast furnace slow-cooled slag and blowing water vapor Has also been proposed (Patent Document 3). Furthermore, as an improvement method of this method, a method of placing sulfur-containing slag such as blast furnace slag on the chromium oxide-containing material and sprinkling water (Patent Document 4) or after blowing steam into the chromium oxide-containing material, blast furnace slag A method (Patent Document 5) in which the elution water is sprinkled or immersed in blast furnace slag elution water has been proposed.
上記の特許文献２〜５に示されている方法は、基本的に硫黄により６価Ｃｒを無害な３価Ｃｒに還元して無害化する方法であり、一時的には６価Ｃｒの溶出が防止されるものの、Ｃｒが完全に安定化されたわけではなく、長期に使用されていると、外部環境によっては再び６価Ｃｒの溶出量が増大する場合があるという問題があった。
The methods shown in the
本発明は、前記した従来技術の問題点を解決し、含クロム鉄鋼スラグを工業的に簡易で経済性に優れた方法で改質し、スラグ中のＣｒを、長期に亘り最大でも６価Ｃｒ溶出量≦０．５ｍｇ／ｌ、望ましくは６価Ｃｒ溶出量≦０．０５ｍｇ／ｌとなるように安定化させる方法を提供することを課題とする。 The present invention solves the above-mentioned problems of the prior art, and modifies chromium-containing steel slag by a method that is industrially simple and excellent in economic efficiency. It is an object of the present invention to provide a method for stabilizing so that the elution amount ≦ 0.5 mg / l, preferably the hexavalent Cr elution amount ≦ 0.05 mg / l.
かかる課題を解決するため、本発明の要旨とするところは、以下の通りである。
（１）酸化クロムを０．８〜１０．２質量％含有する鉄鋼精錬スラグであって、スラグ中の全クロムの８０質量％以上がＦｅＯ・Ｃｒ2Ｏ3および／またはＭｎＯ・Ｃｒ2Ｏ3として存在することを特徴とする、６価Ｃｒ溶出量を０．５ｍｇ／ｌ以下に抑えたスラグ。
（２）酸化クロムを０．８〜１０．２質量％含有する鉄鋼精錬スラグであって、スラグ中の酸化鉄質量と酸化マンガン質量の和がスラグ中全クロム質量の１．５倍以上であることを特徴とする、６価Ｃｒ溶出量を０．５ｍｇ／ｌ以下に抑えたスラグ。
（３）酸化クロムを０．８〜１０．２質量％含有する鉄鋼精錬スラグであって、スラグ中の全クロムの８０質量％以上がＦｅＯ・Ｃｒ2Ｏ3および／またはＭｎＯ・Ｃｒ2Ｏ3として存在し、２ＣａＯ・ＳｉＯ2含有量がスラグ質量に対して３質量％未満であることを特徴とする、６価Ｃｒ溶出量を０．０５ｍｇ／ｌ以下に抑えたスラグ。
（４）酸化クロムを０．８〜１０．２質量％含有する鉄鋼精錬スラグであって、スラグ中の酸化鉄質量と酸化マンガン質量の和がスラグ中全クロム質量の１．５倍以上であり、ＣａＯ、ＳｉＯ2、ＭｇＯ、Ａｌ2Ｏ3以外のスラグ成分を除いたＣａＯ、ＳｉＯ2、ＭｇＯ、Ａｌ2Ｏ3各成分のモル分率をそれぞれｘ、ｙ、ｚ、αとしたときに、下記（Ａ）式で規定される範囲にない組成であることを特徴とする、６価Ｃｒ溶出量を０．０５ｍｇ／ｌ以下に抑えたスラグ。
ｘ−３ｙ≦３α かつ ２ｘ−３ｙ≧６α かつ ２ｘ＋３ｙ≧２−２α かつ
５ｙ≦２−８α かつ α≦０．２５ （Ａ）
（５）ステンレス鋼の精錬中または精錬終了後に、酸化鉄を主成分とする物質および／または酸化マンガンを主成分とする物質を添加することにより、請求項１〜４で規定するスラグとなるようにすることを特徴とする無害化スラグの製造方法。
In order to solve this problem, the gist of the present invention is as follows.
(1) A steel refining slag containing 0.8 to 10.2% by mass of chromium oxide, wherein 80% by mass or more of the total chromium in the slag is FeO · Cr 2 O 3 and / or MnO · Cr 2 O 3 A slag that suppresses the elution amount of hexavalent Cr to 0.5 mg / l or less.
(2) Steel refining slag containing 0.8 to 10.2% by mass of chromium oxide, and the sum of iron oxide mass and manganese oxide mass in the slag is 1.5 times or more of the total chromium mass in the slag The slag which suppressed the elution amount of hexavalent Cr to 0.5 mg / l or less characterized by the above-mentioned.
(3) Steel refining slag containing 0.8 to 10.2% by mass of chromium oxide, wherein 80% by mass or more of the total chromium in the slag is FeO · Cr 2 O 3 and / or MnO · Cr 2 O 3 A slag having a content of 2CaO · SiO 2 of less than 3% by mass with respect to the slag mass, the elution amount of hexavalent Cr being suppressed to 0.05 mg / l or less.
(4) A steel smelting slag containing 0.8 to 10.2% by mass of chromium oxide, wherein the sum of iron oxide mass and manganese oxide mass in the slag is 1.5 times or more of the total chromium mass in the slag. , CaO, SiO 2, MgO, CaO , excluding the slag component other than Al 2 O 3, SiO 2, MgO, Al 2
x-3y ≦ 3α and 2x-3y ≧ 6α and 2x + 3y ≧ 2-2α and
5y ≦ 2-8α and α ≦ 0.25 (A)
(5) By adding a substance mainly composed of iron oxide and / or a substance mainly composed of manganese oxide during or after the refining of stainless steel, the slag defined in
本発明により、含クロム鉄鋼スラグからの６価Ｃｒの溶出を抑制して長期的に無害化し、路盤材、セメント材、海洋用途等の資源化ができるようになった。 According to the present invention, elution of hexavalent Cr from chromium-containing steel slag is suppressed and rendered harmless in the long term, and resources such as roadbed materials, cement materials, and marine applications can be used.
発明者らは、酸化クロムを含む種々の化合物からの６価Ｃｒ溶出量を調査した。その結果、ＦｅＯ・Ｃｒ2Ｏ3やＭｎＯ・Ｃｒ2Ｏ3の形をとる化合物からは、図１に示すように３０日間の長期に亘り化合物を水に浸漬しても、６価Ｃｒの溶出が殆どないことを知見した。 The inventors investigated the elution amount of hexavalent Cr from various compounds including chromium oxide. As a result, even if the compound in the form of FeO.Cr 2 O 3 or MnO.Cr 2 O 3 is immersed in water for a long period of 30 days as shown in FIG. I found that there was almost no.
したがって、発明の最良の実施形態としては、スラグ中のクロムの全量がＦｅＯ・Ｃｒ2Ｏ3もしくはＭｎＯ・Ｃｒ2Ｏ3として存在することであり、これにより６価Ｃｒの溶出量は長期にわたり殆ど皆無となる。しかしながら、工業的にこのような条件を作り出すことは困難であるため、発明者らは種々の含クロム鉄鋼スラグからの６価Ｃｒ溶出量を調査し、溶出量が０．５ｍｇ／ｌ以下となる条件を見出した。すなわち、「スラグ中の全クロムの８０質量％以上がＦｅＯ・Ｃｒ2Ｏ3および／またはＭｎＯ・Ｃｒ2Ｏ3として存在する」、という条件である。数値限定の根拠は以下の通りである。 Therefore, the best mode of the invention is that the total amount of chromium in the slag is present as FeO.Cr 2 O 3 or MnO.Cr 2 O 3 , and thus the elution amount of hexavalent Cr is almost constant over a long period of time. None. However, since it is difficult to create such conditions industrially, the inventors investigated the elution amount of hexavalent Cr from various chromium-containing steel slags, and the elution amount is 0.5 mg / l or less. I found the condition. That is, the condition is that “80% by mass or more of the total chromium in the slag exists as FeO · Cr 2 O 3 and / or MnO · Cr 2 O 3 ”. The basis for the numerical limitation is as follows.
発明者らは種々の含クロム鉄鋼スラグをＥＰＭＡで分析し、スラグ中のＣｒの存在形態を調査した。スラグ中の全クロム質量に対するＦｅＯ・Ｃｒ2Ｏ3中のＣｒ質量とＭｎＯ・Ｃｒ2Ｏ3中Ｃｒ質量の和の比と、環境庁告示４６号に則って測定した６価Ｃｒの溶出量との関係を図２に示す。ＦｅＯ・Ｃｒ2Ｏ3中のＣｒ質量とＭｎＯ・Ｃｒ2Ｏ3中Ｃｒ質量の和がスラグ中全Ｃｒの８０質量％以上であれば、すべて６価Ｃｒ溶出量が０．５ｍｇ／ｌ以下となっている。 The inventors analyzed various chromium-containing steel slags by EPMA and investigated the existence form of Cr in the slags. The ratio of the sum of the Cr mass in FeO · Cr 2 O 3 and the Cr mass in MnO · Cr 2 O 3 with respect to the total chromium mass in the slag, and the elution amount of hexavalent Cr measured according to Environment Agency Notification 46 The relationship is shown in FIG. If the sum of the Cr mass in FeO · Cr 2 O 3 and the Cr mass in MnO · Cr 2 O 3 is 80% by mass or more of the total Cr in the slag, the hexavalent Cr elution amount is 0.5 mg / l or less. It has become.
また、発明者らは、ＦｅＯ・Ｃｒ2Ｏ3中のＣｒ質量とＭｎＯ・Ｃｒ2Ｏ3中Ｃｒ質量の和がスラグ中全Ｃｒの８０質量％以上である含クロム鉄鋼スラグについて、スラグ中の２ＣａＯ・ＳｉＯ2含有量と６価Ｃｒの溶出量との関係を調査した。その結果を図３に示すが、２ＣａＯ・ＳｉＯ2含有量がスラグ質量に対して３質量％未満で６価Ｃｒ溶出量が全て０．０５ｍｇ／ｌ以下となった。すなわち、スラグ中の全クロムの８０質量％以上がＦｅＯ・Ｃｒ2Ｏ3および／またはＭｎＯ・Ｃｒ2Ｏ3として存在し、２ＣａＯ・ＳｉＯ2含有量がスラグ質量に対して３質量％未満である、という２つの条件を同時に満たせば、６価Ｃｒ溶出量０．０５ｍｇ／ｌ以下の土壌環境基準も達成できることが判明した。 In addition, the inventors of the present invention have described the chromium-containing steel slag in which the sum of the Cr mass in FeO · Cr 2 O 3 and the Cr mass in MnO · Cr 2 O 3 is 80% by mass or more of the total Cr in the slag. The relationship between the 2CaO · SiO 2 content and the elution amount of hexavalent Cr was investigated. The results are shown in FIG. 3, and the content of 2CaO.SiO 2 was less than 3% by mass relative to the mass of slag, and the elution amount of hexavalent Cr was all 0.05 mg / l or less. That is, 80% by mass or more of the total chromium in the slag exists as FeO · Cr 2 O 3 and / or MnO · Cr 2 O 3 , and the content of 2CaO · SiO 2 is less than 3% by mass with respect to the slag mass. It was found that the soil environmental standard with a hexavalent Cr elution amount of 0.05 mg / l or less could be achieved if the two conditions were satisfied simultaneously.
スラグ中の全クロムの８０質量％以上がＦｅＯ・Ｃｒ2Ｏ3および／またはＭｎＯ・Ｃｒ2Ｏ3として存在するための実施の形態としては、「スラグ中の酸化鉄質量と酸化マンガン質量の和がスラグ中全クロム質量の１．５倍以上」とすることである。発明者らは種々の組成のスラグを分析し、クロムの存在形態を調査した結果、図４に示すように、全クロム質量に対するスラグ中の酸化鉄質量と酸化マンガン質量の和の比が１．５以上で、ＦｅＯ・Ｃｒ2Ｏ3中のＣｒ質量とＭｎＯ・Ｃｒ2Ｏ3中Ｃｒ質量の和がスラグ中全Ｃｒの８０質量％以上となることを知見した。 As an embodiment in which 80% by mass or more of the total chromium in the slag exists as FeO · Cr 2 O 3 and / or MnO · Cr 2 O 3 , “the sum of the iron oxide mass and the manganese oxide mass in the slag” Is 1.5 times or more of the total chromium mass in the slag. As a result of analyzing the slag of various compositions and investigating the existence form of chromium, the inventors have found that the ratio of the sum of the iron oxide mass and the manganese oxide mass in the slag to the total chromium mass is 1. It was found that the sum of the Cr mass in FeO · Cr 2 O 3 and the Cr mass in MnO · Cr 2 O 3 was 80 mass% or more of the total Cr in the slag.
また、２ＣａＯ・ＳｉＯ2含有量をスラグ質量に対して３質量％未満とするための実施の形態としては、「ＣａＯ、ＳｉＯ2、ＭｇＯ、Ａｌ2Ｏ3以外のスラグ成分を除いたＣａＯ、ＳｉＯ2、ＭｇＯ、Ａｌ2Ｏ3各成分のモル分率をそれぞれｘ、ｙ、ｚ、αとしたときに、下記（Ａ）式で規定される範囲にない組成である」ようにすることである。ここで、
ｘ−３ｙ≦３α かつ ２ｘ−３ｙ≧６α かつ ２ｘ＋３ｙ≧２−２α かつ
５ｙ≦２−８α かつ α≦０．２５ （Ａ）
である。ここで規定される組成範囲の意味合いは以下の通りである。
Further, as an embodiment for setting the 2CaO.SiO 2 content to less than 3% by mass with respect to the slag mass, “CaO, SiO excluding slag components other than CaO, SiO 2 , MgO, Al 2 O 3” 2 , MgO, Al 2 O 3, when the molar fraction of each component is x, y, z, α, respectively, the composition is not within the range defined by the following formula (A). . here,
x-3y ≦ 3α and 2x-3y ≧ 6α and 2x + 3y ≧ 2-2α and
5y ≦ 2-8α and α ≦ 0.25 (A)
It is. The meaning of the composition range specified here is as follows.
図５に、ＣａＯ−ＳｉＯ2−ＭｇＯ−Ａｌ2Ｏ3の４元状態図を示す。図中Ｃ3Ａは３ＣａＯ・Ａｌ2Ｏ3の化合物を生成する組成点を示し、同様にＣ3Ｓは３ＣａＯ・ＳｉＯ2、Ｃ2Ｓは２ＣａＯ・ＳｉＯ2、Ｃ3Ｓ2は３ＣａＯ・２ＳｉＯ2、Ｃ3ＭＳ2は３ＣａＯ・ＭｇＯ・２ＳｉＯ2、Ｃ2ＭＳ2は２ＣａＯ・ＭｇＯ・２ＳｉＯ2の化合物を生成する組成点を示す。このとき、スラグの組成がＣ2Ｓ、Ｃ3Ａ、Ｃ3Ｓ、ＭｇＯの各点を頂点とする４面体、Ｃ2Ｓ、Ｃ3Ａ、Ｃ3ＭＳ2、ＭｇＯの各点を頂点とする４面体、Ｃ2Ｓ、Ｃ3Ａ、Ｃ3ＭＳ2、Ｃ2ＭＳ2の各点を頂点とする４面体、Ｃ2Ｓ、Ｃ3Ａ、Ｃ3Ｓ2、Ｃ2ＭＳ2の各点を頂点とする４面体、のいずれかの内部にある場合は、スラグが冷却して凝固する際にスラグ中に２ＣａＯ・ＳｉＯ2を析出する。スラグ組成が前記４つの４面体のいずれかの内部であることを示す条件が（Ａ）式であり、（Ａ）式で規定される範囲にない組成であればスラグが冷却凝固後に２ＣａＯ・ＳｉＯ2を含まないことになる。発明者らは、種々の組成のスラグを分析し、（Ａ）式で規定される範囲にない組成の場合、２ＣａＯ・ＳｉＯ2含有量がスラグ質量に対して３質量％未満であること、および、スラグ中の全クロムの８０質量％以上がＦｅＯ・Ｃｒ2Ｏ3および／またはＭｎＯ・Ｃｒ2Ｏ3として存在する場合には、６価Ｃｒの溶出量が全て０．０５ｍｇ／ｌ以下であることを確認した。
FIG. 5 shows a quaternary phase diagram of CaO—SiO 2 —MgO—Al 2 O 3 . Figure C 3 A shows the composition point to produce a compound of 3CaO · Al 2 O 3, likewise C 3 S is 3CaO · SiO 2, C 2 S is 2CaO · SiO 2, C 3 S 2 is 3CaO · 2SiO 2, C 3 MS 2 is 3CaO · MgO · 2SiO 2, C 2
上記のような６価Ｃｒ溶出量を抑えたスラグを製造するための具体的な実施の形態は、「ステンレス鋼の精錬中または精錬終了後に、酸化鉄を主成分とする物質および／または酸化マンガンを主成分とする物質を添加すること」である。電気炉やＦｅ−Ｃｒの溶融還元炉、転炉、ＡＯＤといった脱炭炉、二次精錬炉等のステンレス鋼の精錬炉において、精錬初期のフラックスの添加量と精錬前の溶銑や溶鋼の組成から、精錬後のスラグ組成は予測される。予測されたスラグ組成が本発明で規定したスラグ組成となる場合にはそのままで良いが、精錬目的により規定スラグ組成から外れる場合には、精錬末期もしくは精錬終了後に、炉内もしくは排滓鍋において不足成分である酸化鉄もしくは酸化マンガンを補う物質を添加する。酸化鉄分を補う場合には、鉄鉱石、焼結鉱、製鋼ダスト、ミルスケール等の酸化鉄を主成分とする物質が、酸化マンガン分を補う場合には、Ｍｎ鉱石、Ｆｅ−Ｍｎ合金、Ｆｅ−Ｍｎ製造時のダスト等の酸化マンガンを主成分とする物質が使用できる。本発明で規定したスラグ組成とするために、これらの物質を適宜選択して単独もしくは複数を併用して使用すれば良い。なお、物質添加後のスラグとの混合、溶解効率を向上するために、これらの物質を粉砕して細かくしておくとより望ましい。また、排滓鍋において添加する場合には、溶解効率を向上するために、適宜バーナーや電気エネルギーを使用して熱を付与しても良い。 A specific embodiment for producing the slag with reduced hexavalent Cr elution amount as described above is “a substance containing iron oxide as a main component and / or manganese oxide during or after refining of stainless steel. It is to add a substance containing as a main component. In refining furnaces for stainless steel such as electric furnaces, Fe-Cr smelting reduction furnaces, converters, decarburizing furnaces such as AOD, and secondary refining furnaces, the amount of flux added at the initial stage of refining and the composition of hot metal and molten steel before refining The slag composition after refining is predicted. If the predicted slag composition is the slag composition specified in the present invention, it may be left as it is, but if it is out of the specified slag composition for the purpose of refining, it will be insufficient in the furnace or in the ladle after the end of refining or after refining. Add a substance that supplements the component iron oxide or manganese oxide. When supplementing the iron oxide content, iron ore, sintered ore, steelmaking dust, mill scale and other substances mainly composed of iron oxide, when supplementing the manganese oxide content, Mn ore, Fe-Mn alloy, Fe -The substance which has manganese oxide as a main component, such as dust at the time of Mn manufacture, can be used. In order to obtain the slag composition defined in the present invention, these substances may be appropriately selected and used alone or in combination. In order to improve mixing and dissolution efficiency with slag after addition of substances, it is more desirable to pulverize these substances. Moreover, when adding in a waste pan, in order to improve melt | dissolution efficiency, you may provide a heat | fever using a burner and an electrical energy suitably.
以下、本発明を具体例に基づき具体的に説明する。なお、本実施例における６価Ｃｒ溶出量は、環境庁告示４６号法による溶出試験方法に基づいて測定した。 Hereinafter, the present invention will be specifically described based on specific examples. In addition, the hexavalent Cr elution amount in the present Example was measured based on the elution test method by the Environmental Agency Notification No. 46 method.
（実施例１）
１トン規模の試験用溶解炉を用いて、Ｃｒ系ステンレスを溶製、脱炭精錬を行った。脱炭精錬終了時点のスラグ組成は、溶銑成分および精錬終了時の溶鋼成分、造滓材である生石灰とドロマイト、鉄鉱石および珪石の添加量、還元材であるＦｅ−Ｓｉ合金添加量によりマスバランスから計算して調整した。
Example 1
Using a 1-ton scale melting furnace for testing, Cr-based stainless steel was melted and decarburized and refined. The slag composition at the end of decarburization refining is a mass balance depending on the hot metal component, the molten steel component at the end of refining, the addition of quicklime and dolomite as ironmaking materials, the amount of iron ore and silica, and the amount of Fe-Si alloy as a reducing material Calculated and adjusted from
主な結果を表１に示す。発明例１では、脱炭精錬中の上底吹き条件や鉄鉱石の投入量の調整によりスラグ中酸化鉄濃度が高くなるよう調整し、脱炭後のＦｅ−Ｓｉによる還元を行わなかった。最終のスラグ組成が、本発明で規定するスラグ中の酸化鉄質量と酸化マンガン質量の和がスラグ中全クロム質量の１．５倍以上であり、かつＣａＯ、ＳｉＯ2、ＭｇＯ、Ａｌ2Ｏ3以外のスラグ成分を除いたＣａＯ、ＳｉＯ2、ＭｇＯ、Ａｌ2Ｏ3各成分のモル分率が（Ａ）式で規定される範囲にない組成となっており、ＥＰＭＡを用いて分析したスラグ中クロムの存在形態は、スラグ中の全クロムの８０質量％以上がＦｅＯ・Ｃｒ2Ｏ3および／またはＭｎＯ・Ｃｒ2Ｏ3として存在しており、２ＣａＯ・ＳｉＯ2含有量がスラグ質量に対して３質量％未満であった。このスラグからの６価Ｃｒの溶出試験を実施したところ、６価Ｃｒの溶出量が０．０５ｍｇ／ｌ以下であった。 The main results are shown in Table 1. In invention example 1, it adjusted so that the iron oxide density | concentration in slag might become high by adjustment of the top bottom blowing conditions during decarburization refining, and the input amount of iron ore, and the reduction | restoration by Fe-Si after decarburization was not performed. The final slag composition is such that the sum of the iron oxide mass and the manganese oxide mass in the slag defined in the present invention is 1.5 times or more the total chromium mass in the slag, and CaO, SiO 2 , MgO, Al 2 O 3 In the slag analyzed using EPMA, the molar fraction of each component of CaO, SiO 2 , MgO, Al 2 O 3 excluding other slag components is not within the range defined by the formula (A). As for the existence form of chromium, 80% by mass or more of the total chromium in the slag is present as FeO · Cr 2 O 3 and / or MnO · Cr 2 O 3 , and the content of 2CaO · SiO 2 is based on the slag mass. It was less than 3% by mass. When the elution test of hexavalent Cr from this slag was carried out, the elution amount of hexavalent Cr was 0.05 mg / l or less.
また、発明例２〜７は、脱炭後にＦｅ−Ｓｉ還元を行い、還元後に転炉ダストやＭｎ鉱石を用いてスラグを改質した。発明例２と５では、転炉ダストのみをマスバランスから計算されたスラグ量の７質量％に相当する量を排滓鍋に敷き込み、その上にスラグを排出した。発明例３と６では、Ｍｎ鉱石のみをマスバランスから計算されたスラグ量の７質量％に相当する量を排滓鍋に敷き込み、その上にスラグを排出した。発明例４と７では、転炉ダストとＭｎ鉱石をそれぞれ計算スラグ量の３質量％に相当する量ずつ混合して排滓鍋に敷き込み、その上にスラグを排出した。 In Invention Examples 2 to 7, Fe—Si reduction was performed after decarburization, and slag was modified using converter dust and Mn ore after reduction. In Invention Examples 2 and 5, only the converter dust was laid on the slag pan in an amount corresponding to 7% by mass of the slag amount calculated from the mass balance, and the slag was discharged thereon. In Invention Examples 3 and 6, only the Mn ore was laid on the slag pan in an amount corresponding to 7% by mass of the slag amount calculated from the mass balance, and the slag was discharged thereon. In Invention Examples 4 and 7, converter dust and Mn ore were mixed in an amount corresponding to 3% by mass of the calculated amount of slag, laid in a slag pan, and slag was discharged thereon.
発明例２〜４は、スラグ中の酸化鉄質量と酸化マンガン質量の和はスラグ中全クロム質量の１．５倍以上であり、スラグ中の全クロムの８０質量％以上がＦｅＯ・Ｃｒ2Ｏ3および／またはＭｎＯ・Ｃｒ2Ｏ3として存在していたが、ＣａＯ、ＳｉＯ2、ＭｇＯ、Ａｌ2Ｏ3以外のスラグ成分を除いたＣａＯ、ＳｉＯ2、ＭｇＯ、Ａｌ2Ｏ3各成分のモル分率が（Ａ）式で規定される範囲内であり、２ＣａＯ・ＳｉＯ2含有量がスラグ質量に対して３質量％以上であった。これらのスラグからの６価Ｃｒの溶出試験を実施したところ、６価Ｃｒの溶出量が０．５ｍｇ／ｌ以下であった。発明例５〜７については、スラグ中の酸化鉄質量と酸化マンガン質量の和がスラグ中全クロム質量の１．５倍以上であり、かつＣａＯ、ＳｉＯ2、ＭｇＯ、Ａｌ2Ｏ3以外のスラグ成分を除いたＣａＯ、ＳｉＯ2、ＭｇＯ、Ａｌ2Ｏ3各成分のモル分率が（Ａ）式で規定される範囲にない組成となっており、スラグ中の全クロムの８０質量％以上がＦｅＯ・Ｃｒ2Ｏ3および／またはＭｎＯ・Ｃｒ2Ｏ3として存在しており、２ＣａＯ・ＳｉＯ2含有量がスラグ質量に対して３質量％未満であった。これらのスラグからの６価Ｃｒの溶出量が０．０５ｍｇ／ｌ以下であった。
In Invention Examples 2 to 4, the sum of the iron oxide mass and the manganese oxide mass in the slag is 1.5 times or more of the total chromium mass in the slag, and 80 mass% or more of the total chromium in the slag is FeO · Cr 2 O. 3 and / or was present as MnO · Cr 2 O 3, CaO ,
比較例では、脱炭後にＦｅ−Ｓｉ還元を行ったが、スラグ改質は実施しなかった。比較例１、２とも、スラグ中の酸化鉄質量と酸化マンガン質量の和がスラグ中全クロム質量の１．５倍未満であり、スラグ中の全クロム質量に対するＦｅＯ・Ｃｒ2Ｏ3中クロム質量とＭｎＯ・Ｃｒ2Ｏ3中クロム質量の和の比が８０質量％未満であった。これらのスラグからの６価Ｃｒの溶出試験を実施したところ、６価Ｃｒの溶出量が０．５ｍｇ／ｌ超であった。 In the comparative example, Fe-Si reduction was performed after decarburization, but slag reforming was not performed. In Comparative Examples 1 and 2, the sum of the iron oxide mass and the manganese oxide mass in the slag is less than 1.5 times the total chromium mass in the slag, and the chromium mass in FeO · Cr 2 O 3 with respect to the total chromium mass in the slag The ratio of the sum of the chromium masses in MnO · Cr 2 O 3 was less than 80% by mass. When the elution test of hexavalent Cr from these slags was performed, the elution amount of hexavalent Cr was more than 0.5 mg / l.
（実施例２）
１トン規模の試験用溶解炉を用いて、Ｃｒ系ステンレスを溶製、脱炭精錬を行った後、真空精錬炉で［Ｃ］＜０．１質量％まで脱炭し、その後、鍋底に取り付けたポーラスプラグからＡｒバブリングをしながら脱酸した。脱酸は、金属Ａｌ、Ｆｅ−Ｓｉ合金、Ｃａ−Ｓｉ合金の単独または併用で行い、脱酸材の添加量により脱酸後のスラグ組成を調整した。
(Example 2)
After melting and decarburizing and refining Cr-based stainless steel using a 1-ton scale melting furnace, [C] <0.1% by mass in a vacuum refining furnace, and then attaching to the bottom of the pan The porous plug was deoxidized with Ar bubbling. Deoxidation was performed using metal Al, Fe—Si alloy, or Ca—Si alloy alone or in combination, and the slag composition after deoxidation was adjusted by the amount of deoxidizer added.
主な結果を表２に示す。発明例８〜１０では、脱酸後のスラグを排出する際、排滓鍋に鉄鉱石やＭｎ鉱石を敷き込み、その上に排滓してスラグを改質した。発明例８では、マスバランスから計算されたスラグ量の１質量％に相当する量の鉄鉱石のみを、発明例９では計算スラグ量の１質量％に相当する量のＭｎ鉱石のみを、発明例１０ではそれぞれ計算スラグ量の１質量％に相当する量の鉄鉱石とＭｎ鉱石を混合したものを改質材として使用した。 The main results are shown in Table 2. In Invention Examples 8 to 10, when discharging the slag after deoxidation, iron ore or Mn ore was laid in the slag pan, and slag was reformed by laying on it. In Invention Example 8, only iron ore in an amount corresponding to 1% by mass of the slag amount calculated from the mass balance is obtained, and in Invention Example 9, only Mn ore in an amount corresponding to 1% by mass of the calculated slag amount is obtained. In No. 10, a mixture of iron ore and Mn ore in an amount corresponding to 1% by mass of the calculated slag amount was used as a modifier.
発明例８、９では、スラグ中の酸化鉄質量と酸化マンガン質量の和はスラグ中全クロム質量の１．５倍以上であり、スラグ中の全クロムの８０質量％以上がＦｅＯ・Ｃｒ2Ｏ3および／またはＭｎＯ・Ｃｒ2Ｏ3として存在していたが、ＣａＯ、ＳｉＯ2、ＭｇＯ、Ａｌ2Ｏ3以外のスラグ成分を除いたＣａＯ、ＳｉＯ2、ＭｇＯ、Ａｌ2Ｏ3各成分のモル分率が（Ａ）式で規定される範囲内であり、２ＣａＯ・ＳｉＯ2含有量がスラグ質量に対して３質量％以上であった。これらのスラグからの６価Ｃｒの溶出試験を実施したところ、６価Ｃｒの溶出量が０．５ｍｇ／ｌ以下であった。また、発明例１０では、スラグ中の酸化鉄質量と酸化マンガン質量の和がスラグ中全クロム質量の１．５倍以上であり、かつＣａＯ、ＳｉＯ2、ＭｇＯ、Ａｌ2Ｏ3以外のスラグ成分を除いたＣａＯ、ＳｉＯ2、ＭｇＯ、Ａｌ2Ｏ3各成分のモル分率が（Ａ）式で規定される範囲にない組成となっており、スラグ中の全クロムの８０質量％以上がＦｅＯ・Ｃｒ2Ｏ3および／またはＭｎＯ・Ｃｒ2Ｏ3として存在しており、２ＣａＯ・ＳｉＯ2含有量がスラグ質量に対して３質量％未満であった。このスラグからの６価Ｃｒの溶出量が０．０５ｍｇ／ｌ以下であった。
In Invention Examples 8 and 9, the sum of the iron oxide mass and the manganese oxide mass in the slag is 1.5 times or more of the total chromium mass in the slag, and 80 mass% or more of the total chromium in the slag is FeO · Cr 2 O. 3 and / or was present as MnO · Cr 2 O 3, CaO ,
比較例では、脱酸後のスラグ改質は実施しなかった。比較例３、４とも、スラグ中の酸化鉄質量と酸化マンガン質量の和がスラグ中全クロム質量の１．５倍未満であり、スラグ中の全クロム質量に対するＦｅＯ・Ｃｒ2Ｏ3中クロム質量とＭｎＯ・Ｃｒ2Ｏ3中クロム質量の和の比が８０質量％未満であった。これらのスラグからの６価Ｃｒの溶出試験を実施したところ、６価Ｃｒの溶出量が０．５ｍｇ／ｌ超であった。 In the comparative example, slag modification after deoxidation was not performed. In Comparative Examples 3 and 4, the sum of the iron oxide mass and the manganese oxide mass in the slag is less than 1.5 times the total chromium mass in the slag, and the chromium mass in FeO · Cr 2 O 3 with respect to the total chromium mass in the slag The ratio of the sum of the chromium masses in MnO · Cr 2 O 3 was less than 80% by mass. When the elution test of hexavalent Cr from these slags was performed, the elution amount of hexavalent Cr was more than 0.5 mg / l.
また、発明例１〜１０のスラグを、環境庁告示４６号法による溶出試験と同じ要領で、５００ｍｌの水にスラグ５０ｇを浸漬し、１年間溶出させた後に６価Ｃｒの溶出量を測定した。結果を表３に示す。１年間の溶出試験後も、いずれも６価Ｃｒの溶出量は０．０５ｍｇ／ｌであり、長期的に安定であることも確認された。 In addition, the slag of Invention Examples 1 to 10 was dissolved in 500 ml of water in the same manner as the dissolution test by the Environmental Agency Notification No. 46 method, and after 5 years of dissolution, the elution amount of hexavalent Cr was measured. . The results are shown in Table 3. Even after one year of dissolution test, the dissolution amount of hexavalent Cr was 0.05 mg / l, which was confirmed to be stable in the long term.
Claims (5)
ｘ−３ｙ≦３α かつ ２ｘ−３ｙ≧６α かつ ２ｘ＋３ｙ≧２−２α かつ
５ｙ≦２−８α かつ α≦０．２５ （Ａ） Steel refining slag containing 0.8 to 10.2% by mass of chromium oxide, the sum of iron oxide mass and manganese oxide mass in the slag is 1.5 times or more of the total chromium mass in the slag, CaO, SiO 2, MgO, CaO, excluding the slag component other than Al 2 O 3, SiO 2, MgO, Al 2 O 3 mole fraction of each component, respectively x, y, z, when a alpha, the following (a ) Slag with a hexavalent Cr elution amount suppressed to 0.05 mg / l or less, characterized in that the composition is not within the range defined by the formula.
x-3y ≦ 3α and 2x-3y ≧ 6α and 2x + 3y ≧ 2-2α and
5y ≦ 2-8α and α ≦ 0.25 (A)
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