JP5444883B2 - Modified slag - Google Patents
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- JP5444883B2 JP5444883B2 JP2009152703A JP2009152703A JP5444883B2 JP 5444883 B2 JP5444883 B2 JP 5444883B2 JP 2009152703 A JP2009152703 A JP 2009152703A JP 2009152703 A JP2009152703 A JP 2009152703A JP 5444883 B2 JP5444883 B2 JP 5444883B2
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- 239000002893 slag Substances 0.000 title claims description 403
- 230000009467 reduction Effects 0.000 claims description 167
- 238000009628 steelmaking Methods 0.000 claims description 147
- 238000002407 reforming Methods 0.000 claims description 135
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 85
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 71
- 229910052799 carbon Inorganic materials 0.000 claims description 71
- 229910052751 metal Inorganic materials 0.000 claims description 67
- 239000002184 metal Substances 0.000 claims description 67
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 65
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 47
- 239000000155 melt Substances 0.000 claims description 45
- 238000010438 heat treatment Methods 0.000 claims description 36
- 238000006243 chemical reaction Methods 0.000 claims description 31
- 239000003607 modifier Substances 0.000 claims description 24
- 229910052742 iron Inorganic materials 0.000 claims description 20
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims description 6
- 229910001882 dioxygen Inorganic materials 0.000 claims description 6
- 238000006722 reduction reaction Methods 0.000 description 188
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 122
- 239000000571 coke Substances 0.000 description 45
- 230000002829 reductive effect Effects 0.000 description 31
- 239000007789 gas Substances 0.000 description 29
- 238000000034 method Methods 0.000 description 27
- 239000000463 material Substances 0.000 description 26
- 239000000203 mixture Substances 0.000 description 21
- 229910052698 phosphorus Inorganic materials 0.000 description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 21
- 239000010883 coal ash Substances 0.000 description 20
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 19
- 239000011574 phosphorus Substances 0.000 description 19
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 18
- 229910052760 oxygen Inorganic materials 0.000 description 18
- 239000001301 oxygen Substances 0.000 description 18
- 238000002485 combustion reaction Methods 0.000 description 15
- 239000000126 substance Substances 0.000 description 14
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 13
- 239000004568 cement Substances 0.000 description 13
- 238000002474 experimental method Methods 0.000 description 13
- 239000002699 waste material Substances 0.000 description 13
- 229910002091 carbon monoxide Inorganic materials 0.000 description 12
- 230000000694 effects Effects 0.000 description 10
- 229910000831 Steel Inorganic materials 0.000 description 9
- 238000002441 X-ray diffraction Methods 0.000 description 9
- 238000002844 melting Methods 0.000 description 9
- 230000008018 melting Effects 0.000 description 9
- 230000008569 process Effects 0.000 description 9
- 239000002994 raw material Substances 0.000 description 9
- 239000010959 steel Substances 0.000 description 9
- 238000004458 analytical method Methods 0.000 description 8
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- 230000007423 decrease Effects 0.000 description 8
- 229910052748 manganese Inorganic materials 0.000 description 8
- 239000011572 manganese Substances 0.000 description 8
- 239000003575 carbonaceous material Substances 0.000 description 7
- 238000011946 reduction process Methods 0.000 description 7
- 238000003756 stirring Methods 0.000 description 7
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 6
- 238000010521 absorption reaction Methods 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 238000000926 separation method Methods 0.000 description 6
- 239000004575 stone Substances 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 5
- 239000013589 supplement Substances 0.000 description 5
- 239000011398 Portland cement Substances 0.000 description 4
- 239000003638 chemical reducing agent Substances 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 3
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 3
- 230000032683 aging Effects 0.000 description 3
- 239000011575 calcium Substances 0.000 description 3
- 238000007667 floating Methods 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 238000006057 reforming reaction Methods 0.000 description 3
- 239000004576 sand Substances 0.000 description 3
- 229910052717 sulfur Inorganic materials 0.000 description 3
- 239000011593 sulfur Substances 0.000 description 3
- BSWWXRFVMJHFBN-UHFFFAOYSA-N 2,4,6-tribromophenol Chemical compound OC1=C(Br)C=C(Br)C=C1Br BSWWXRFVMJHFBN-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 210000000988 bone and bone Anatomy 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000005261 decarburization Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 239000003337 fertilizer Substances 0.000 description 2
- 230000012447 hatching Effects 0.000 description 2
- 238000006703 hydration reaction Methods 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 239000003915 liquefied petroleum gas Substances 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 238000010583 slow cooling Methods 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- 239000002023 wood Substances 0.000 description 2
- 239000002028 Biomass Substances 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910001570 bauxite Inorganic materials 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 239000004035 construction material Substances 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- YWEUIGNSBFLMFL-UHFFFAOYSA-N diphosphonate Chemical compound O=P(=O)OP(=O)=O YWEUIGNSBFLMFL-UHFFFAOYSA-N 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 238000000265 homogenisation Methods 0.000 description 1
- BHEPBYXIRTUNPN-UHFFFAOYSA-N hydridophosphorus(.) (triplet) Chemical compound [PH] BHEPBYXIRTUNPN-UHFFFAOYSA-N 0.000 description 1
- 238000007373 indentation Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920001021 polysulfide Polymers 0.000 description 1
- 239000005077 polysulfide Substances 0.000 description 1
- 150000008117 polysulfides Polymers 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
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- 230000007704 transition Effects 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B5/00—Treatment of metallurgical slag ; Artificial stone from molten metallurgical slag
- C04B5/06—Ingredients, other than water, added to the molten slag or to the granulating medium or before remelting; Treatment with gases or gas generating compounds, e.g. to obtain porous slag
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
- Furnace Details (AREA)
Description
本発明は、製鋼スラグを加熱手段で加熱しながら、SiO2含有改質材および還元用炭素源を添加し、製鋼スラグを溶融改質還元処理する製鋼スラグの処理方法及びこの処理により得られる改質スラグに関する。 The present invention provides a steelmaking slag treatment method in which a steelmaking slag is melt-modified and reduced by adding a SiO 2 -containing reforming material and a reducing carbon source while heating the steelmaking slag with a heating means, and a modification obtained by this treatment. Concerning quality slag.
溶銑予備処理及び脱炭工程等の製鋼工程の精錬処理で発生する製鋼スラグは、遊離CaO(以下、「f・CaO」と記載する。)を含み、このf・CaOの水和反応により体積が膨張し、多くの微小な亀裂や開気孔を生ずる場合がある。このようなf・CaOを多く含む製鋼スラグは体積安定性が低い。また、溶融状態(流動性を有する状態)の製鋼スラグはCOガスを主とする気泡を多く含んでおり、このような気泡を多く含む溶融状態の製鋼スラグを冷却すると気泡を含んだ状態で凝固してしまうため、低品質のものとなる。 The steelmaking slag generated in the refining process of the steelmaking process such as the hot metal pretreatment and the decarburization process contains free CaO (hereinafter referred to as “f · CaO”), and its volume is increased by the hydration reaction of this f · CaO. It may expand and create many microcracks and open pores. Such a steelmaking slag containing a large amount of f · CaO has low volume stability. In addition, the steelmaking slag in the molten state (the state having fluidity) contains many bubbles mainly composed of CO gas. When the molten steelmaking slag containing many bubbles is cooled, the steelmaking slag is solidified in the state containing the bubbles. Therefore, the quality is low.
そのため、製鋼スラグは、土木工事用の仮設材、道路の地盤改良材、下層路盤材等の低級用途に専ら使用され、より高級用途である上層路盤材、コンクリート用骨材、石材原料等には用いられにくい。 Therefore, steelmaking slag is used exclusively for low-grade applications such as temporary construction materials for civil engineering, road ground improvement materials, lower-layer roadbed materials, etc., and for higher-grade applications such as upper-layer roadbed materials, concrete aggregates, and stone raw materials. It is difficult to use.
これに対して、製鋼スラグを上述のような高級用途に有効利用するために、製鋼スラグ中のf・CaOを低減させたり、溶融状態の製鋼スラグ中の気泡を低減させたりすることにより、製鋼スラグの高品質化を図り、商品価値を高めることが行われている。 On the other hand, in order to effectively use steelmaking slag for high-grade applications as described above, steelmaking slag is reduced by reducing f · CaO in steelmaking slag or by reducing bubbles in molten steelmaking slag. The quality of slag is being improved and the product value is being increased.
例えば、特許文献1には、SiO2含有改質材を添加して塩基度を低下させるとともに、還元用炭素源を添加して酸化鉄量を低減させてCOガスを主とする気泡の発生を抑制することが記載されている。また、特許文献1には、SiO2、Al2O3、MgOのうちの少なくともいずれか1種を含有する物質を添加し、スラグの溶融温度を低下させることも記載されている。
For example, in
また、例えば、特許文献2には、スラグ中の酸化鉄やP2O5等の酸化物の濃度を低減させるために、ランスから吹き込まれた酸素による製鋼スラグのへこみ深さLSと製鋼スラグの厚みLS0との比LS/LS0を所定の範囲に制限することが記載されている。また、特許文献2には、改質材として、Al2O3をさらに含む改質材を使用してもよいことも記載されている。
Further, for example, in
ところで、本発明者らの検討によれば、所定量以上のAl2O3を含む改質材を添加すると、還元用炭素源による酸化鉄やP2O5等の酸化物の還元速度を向上させることができるが、Al2O3の濃度が高くなり過ぎると、溶融改質還元処理中のスラグの粘性が高くなり、逆に還元速度を低下させてしまうことがわかった。また、この場合、溶融改質処理の際に添加した還元用炭素源中の炭素分とスラグとの分離が阻害され、炭素分が処理後のスラグ中に残留してしまうため、処理後のスラグの強度の低下を招くということもわかった。 By the way, according to the study by the present inventors, when a modifier containing a predetermined amount or more of Al 2 O 3 is added, the reduction rate of oxides such as iron oxide and P 2 O 5 by the reducing carbon source is improved. However, it has been found that if the concentration of Al 2 O 3 becomes too high, the viscosity of the slag during the melt reforming reduction treatment increases, and conversely the reduction rate decreases. Further, in this case, separation of carbon and slag in the carbon source for reduction added during the melt reforming process is hindered, and the carbon remains in the slag after treatment. It has also been found that this leads to a decrease in strength.
これに対して、特許文献1及び特許文献2には、Al2O3を含む改質材を添加する点は記載されているが、適切な添加量については規定されていない。
On the other hand,
そこで、本発明は、このような事情に鑑みてなされたもので、製鋼スラグを溶融改質還元処理する製鋼スラグの処理方法及びこの処理により得られる改質スラグにおいて、Al2O3の適切な添加量を規定することにより、製鋼スラグ中の酸化鉄やP2O5等の酸化物還元速度を向上させるとともに、緻密で強度の高い改質された製鋼スラグを得ることを目的とする。 Therefore, the present invention has been made in view of such circumstances, and in a steelmaking slag treatment method for subjecting steelmaking slag to a melt reforming reduction treatment, and a modified slag obtained by this treatment, an appropriate Al 2 O 3 content can be obtained. By defining the addition amount, it is an object to improve the steel reduction slag with high density and high strength while improving the reduction rate of oxides such as iron oxide and P 2 O 5 in the steelmaking slag.
本発明者らは、上記課題を解決するために鋭意研究を重ねた結果、溶融改質還元処理を通じて製鋼スラグ中のAl2O3濃度が所定濃度となるようにAl2O3含有物質の添加量を決定するとともに、溶融改質還元処理後の製鋼スラグの塩基度が所定の値以上となるようにSiO2含有改質材の添加量を決定することにより、製鋼スラグ中の酸化鉄やP2O5等の酸化物還元速度を向上させるとともに、緻密で強度の高い製鋼スラグを得ることができることを見出し、この知見に基づいて本発明を完成するに至った。 As a result of intensive studies to solve the above problems, the present inventors have added an Al 2 O 3 -containing substance so that the Al 2 O 3 concentration in the steelmaking slag becomes a predetermined concentration through the melt reforming reduction treatment. In addition to determining the amount, the addition amount of the SiO 2 -containing modifier is determined so that the basicity of the steelmaking slag after the melt reforming reduction treatment is not less than a predetermined value, so that iron oxide and P in the steelmaking slag can be obtained. It has been found that a steelmaking slag with high density and high strength can be obtained while improving the oxide reduction rate of 2 O 5 or the like, and the present invention has been completed based on this finding.
本発明によれば、溶銑が保持されている反応容器に装入された製鋼スラグを、酸素ガスを使用する加熱手段で加熱しながら、前記製鋼スラグにSiO2含有改質材および還元用炭素源を添加し、前記製鋼スラグを溶融改質還元処理して得られる改質スラグであって、前記改質スラグ中のAl2O3濃度が7質量%以上20質量%以下であり、前記改質スラグの塩基度が0.7以上であり、前記改質スラグ中のS濃度が0.7質量%以下であり、前記改質スラグ中のトータル鉄の濃度が1質量%以下である、改質スラグが提供される。
According to the present invention, the steel slag hot metal is charged to the reaction vessel which is held with heating in a heating means using oxygen gas, SiO 2 content modifier and a carbon source for the reduction in the steelmaking slag The modified slag obtained by subjecting the steelmaking slag to a melt reforming reduction treatment, wherein the Al 2 O 3 concentration in the reformed slag is 7% by mass or more and 20% by mass or less. and the basicity of the slag is 0.7 or more, the S concentration in the reformed slag Ri der than 0.7 wt%, the concentration of total iron in the reformed slag is not more than 1 wt%, modified Quality slag is provided.
さらに、前記改質スラグ中のMgO濃度が15質量%以下であることが好ましい。 Furthermore, the MgO concentration in the modified slag is preferably 15% by mass or less.
本発明によれば、製鋼スラグを溶融改質還元処理する製鋼スラグの処理方法及びこの処理により得られる改質スラグにおいて、溶融改質還元処理を通じて製鋼スラグ中のAl2O3濃度が所定濃度となるようにAl2O3含有物質を添加するとともに、溶融改質還元処理後の製鋼スラグの塩基度が所定の値以上となるようにSiO2含有改質材を添加することにより、改質還元処理中の製鋼スラグの粘度を低下させ、これにより、製鋼スラグ中の酸化鉄やP2O5等の酸化物還元速度を向上させるとともに、緻密で強度の高い改質された製鋼スラグを得ることが可能となる。 According to the present invention, in a steelmaking slag treatment method for subjecting steelmaking slag to a melt reforming reduction treatment and a reformed slag obtained by this treatment, the concentration of Al 2 O 3 in the steelmaking slag is a predetermined concentration through the melt reforming reduction treatment. with the addition of Al 2 O 3 containing substance such that, by adding SiO 2 containing modifier as basicity of the steel slag after melting reforming reduction treatment is equal to or greater than a predetermined value, modification reduction Decreasing the viscosity of steelmaking slag during processing, thereby improving the reduction rate of oxides such as iron oxide and P 2 O 5 in steelmaking slag, and obtaining a refined steelmaking slag with high density and high strength Is possible.
以下に添付図面を参照しながら、本発明の好適な実施の形態について詳細に説明する。 Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
[本発明に係る製鋼スラグの処理方法について]
初めに、本発明に係る製鋼スラグの処理方法の概略について説明する。本発明に係る製鋼スラグの処理方法は、製鋼スラグを加熱手段で加熱しながら、製鋼スラグにSiO2含有改質材および還元用炭素源を添加し、製鋼スラグを溶融改質還元処理する方法である。すなわち、本発明に係る製鋼スラグの処理方法では、製鋼スラグを反応容器に装入した後に、加熱手段を用いて加熱して溶融させた製鋼スラグに対してSiO2含有改質材および還元用炭素源を添加し、製鋼スラグを溶融状態で改質及び還元する。なお、製鋼スラグは、種湯として溶銑が保持されている反応容器に装入される。以下、このような本発明に係る製鋼スラグの処理方法に関する各項目について詳細に説明する。
[About the steel slag treatment method according to the present invention]
First, an outline of the steel slag treatment method according to the present invention will be described. The steelmaking slag treatment method according to the present invention is a method of adding a SiO 2 -containing modifier and a reducing carbon source to a steelmaking slag while heating the steelmaking slag with a heating means, and subjecting the steelmaking slag to a melt reforming reduction treatment. is there. That is, in the steelmaking slag treatment method according to the present invention, the steelmaking slag is charged into the reaction vessel and then heated and melted by using a heating means, and the SiO 2 -containing modifier and reducing carbon The source is added and the steelmaking slag is reformed and reduced in the molten state. The steelmaking slag is charged into a reaction vessel in which hot metal is held as seed hot water. Hereinafter, each item regarding such a steelmaking slag processing method according to the present invention will be described in detail.
(製鋼スラグの種類)
本発明は製鋼スラグを改質処理の対象としており、改質対象の製鋼スラグとしては、特に限定されるものではなく、例えば、脱炭スラグ、溶銑予備処理スラグ、電気炉スラグ等を使用することができる。
(Types of steelmaking slag)
In the present invention, steelmaking slag is subject to reforming treatment, and the steelmaking slag to be reformed is not particularly limited. For example, decarburization slag, hot metal pretreatment slag, electric furnace slag, or the like is used. Can do.
(処理中のスラグの状態)
また、本発明では、上述したように製鋼スラグを加熱手段により溶融させ、製鋼スラグが溶融した状態で改質処理及び還元処理を行う。このように溶融状態で処理を行うのは、f・CaOの滓化(溶融均一化)やスラグの還元反応を促進するためには、処理対象のスラグが溶融状態であることが有効だからである。以下、この点についてより詳細に説明する。
(Status of slag being processed)
In the present invention, as described above, the steelmaking slag is melted by the heating means, and the reforming process and the reduction process are performed in a state where the steelmaking slag is melted. The reason why the treatment is performed in the molten state is that it is effective that the slag to be treated is in a molten state in order to promote the f · CaO hatching (melting homogenization) and the reduction reaction of the slag. . Hereinafter, this point will be described in more detail.
(製鋼スラグの改質処理)
溶融状態の製鋼スラグにSiO2含有改質材を添加して改質処理を行うことにより、製鋼スラグ中の未反応のf・CaOを滓化させ、滓化したf・CaOとSiO2等との反応によりf・CaOを低減させることができる。したがって、f・CaOの水和反応(Ca+2H2O→Ca(OH)2+H2)による体積膨張を防止することができる。ここで、溶融状態で改質処理を行うのは、溶融温度未満で改質処理を行った場合には、処理前に未滓化のスラグが固相として残存し、固相として高融点の析出相が残存する場合があるため、SiO2との反応が十分に進行せず、安定してf・CaOを減少させることができないためである。
(Improvement of steelmaking slag)
By adding a SiO 2 -containing modifier to the molten steelmaking slag and performing a reforming treatment, unreacted f · CaO in the steelmaking slag is hatched, and the hatched f · CaO and SiO 2 are By this reaction, f · CaO can be reduced. Therefore, volume expansion due to the hydration reaction of f · CaO (Ca + 2H 2 O → Ca (OH) 2 + H 2 ) can be prevented. Here, the reforming process is performed in a molten state when the reforming process is performed at a temperature lower than the melting temperature, unsaturated slag remains as a solid phase before the process, and a high melting point precipitate is formed as the solid phase. This is because a phase may remain, so that the reaction with SiO 2 does not proceed sufficiently, and f · CaO cannot be reduced stably.
なお、本発明における「溶融状態」とは流動性を有する状態であれば良く、必ずしも改質還元処理開始前から完全に液相である必要はない。具体的な指標としては、スラグ組成から市販の熱力学計算モデルソフト(例えば、SOLGASMIX)で求めた推定値で表すと、液相率が30%以上であれば良い。改質還元処理の進行に伴い、加熱や改質材の溶射により塩基度が低下することで固相率が低下し、その結果、スラグの流動性がさらに向上し改質還元処理が促進される。 The “molten state” in the present invention may be in a state having fluidity, and does not necessarily need to be completely in a liquid phase before the start of the reforming and reducing treatment. As a specific index, when expressed by an estimated value obtained from a slag composition by commercially available thermodynamic calculation model software (for example, SOLGASMIX), the liquid phase ratio may be 30% or more. As the reforming and reduction treatment progresses, the solidity ratio decreases due to a decrease in basicity due to heating or thermal spraying of the reforming material. As a result, the fluidity of the slag is further improved and the reforming and reduction treatment is promoted. .
(製鋼スラグの還元処理)
本発明では、溶融状態で製鋼スラグの還元処理を行うことにより、製鋼スラグ中の酸化鉄を低減し(これにより、トータル鉄(以下、「T.Fe」と記載する。)が低減される。)、COガスを主とする気泡の発生を防止することができる。このCOガスの気泡は、転炉などから排出された直後の溶融状態の製鋼スラグ(以下、「溶融スラグ」と記載する場合がある。)中には粒鉄が懸濁しており、この懸濁粒鉄に含まれる炭素と溶融スラグ中の酸化鉄とが反応することにより発生する。そこで、溶融スラグ中の酸化鉄を還元して酸素源である酸化鉄の量を低減させることにより、COガスの発生を防止することができる。
(Reduction treatment of steelmaking slag)
In the present invention, the iron oxide in the steelmaking slag is reduced by reducing the steelmaking slag in the molten state (thereby reducing the total iron (hereinafter referred to as “T.Fe”)). ), Generation of bubbles mainly composed of CO gas can be prevented. The CO gas bubbles are suspended in granular iron in a molten steelmaking slag immediately after being discharged from a converter or the like (hereinafter sometimes referred to as “molten slag”). It is generated when carbon contained in granular iron reacts with iron oxide in molten slag. Therefore, the generation of CO gas can be prevented by reducing the amount of iron oxide as an oxygen source by reducing the iron oxide in the molten slag.
本発明ではまた、溶融状態で製鋼スラグの還元処理を行うことにより、製鋼スラグ中のT.Feを低減させることで、スラグを白色化または透明化して外観を改善し、スラグの高付加価値化を図ることができる。スラグは、T.Feが多い場合は黒色を呈しているが、スラグ中のFeOやFe2O3を還元してT.Feを低減させると、還元処理後のスラグを脱色させて白色または透明に近づけることができる。このようにT.Feが多く黒色を呈している製鋼スラグを白色化または透明化して、コンクリート骨材としてセメントとともに混合すること等ができれば、還元処理後の製鋼スラグの用途を著しく拡げることができる。そのためには、セメントと同等またはセメントよりも白色化することが必要となる。セメントよりも黒色の強いスラグを骨材として混合した場合、コンクリート内に黒色の点として現れ、外観を損ねることになるからである。 In the present invention, the T. slag in the steelmaking slag is also obtained by reducing the steelmaking slag in a molten state. By reducing Fe, the appearance of the slag can be whitened or transparent to improve the appearance, and the slag can have high added value. The slag When there is much Fe, it is black, but FeO and Fe 2 O 3 in the slag are reduced to reduce T.I. When Fe is reduced, the slag after the reduction treatment can be decolorized to be close to white or transparent. In this way, T.W. If the steelmaking slag having a large amount of Fe and blackened can be whitened or made transparent and mixed with cement as a concrete aggregate, the use of the steelmaking slag after the reduction treatment can be remarkably expanded. For that purpose, it is necessary to make it whiter than cement or whiter than cement. This is because when black slag stronger than cement is mixed as an aggregate, it appears as a black dot in the concrete and the appearance is impaired.
具体的には、本発明者らが行った実験の結果によれば、還元処理により製鋼スラグ中のT.Feの濃度を1.5質量%以下とすると、普通ポルトランドセメントに骨材として混合してもセメントの外観を損ねることはないため、好ましい。また、T.Feが0.5質量%以下にまで低減すると、白色セメントの白色度に匹敵し、より高級な用途である白色セメントの骨材として使用することができるので、還元処理により製鋼スラグ中のT.Feを0.5質量%以下とすることが特に好ましい。 Specifically, according to the results of experiments conducted by the present inventors, T.O. When the Fe concentration is 1.5% by mass or less, even if it is mixed with ordinary Portland cement as an aggregate, the appearance of the cement is not impaired, which is preferable. T. When Fe is reduced to 0.5% by mass or less, the whiteness of the white cement is comparable to that of white cement and can be used as an aggregate of white cement, which is a higher-grade application. It is particularly preferable that Fe be 0.5% by mass or less.
本発明ではまた、溶融状態で製鋼スラグの還元処理を行うことにより、製鋼スラグ中の鉄、リン、マンガン等の有価成分を回収することができる。製鋼スラグ中には、CaO、SiO2の他に、鉄、リン、マンガン等の有価金属が酸化物(FeO、MnO、P2O5等)の形で多く含有されている。そこで、溶銑を種湯として用いている場合には、これらの有価成分の酸化物を、製鋼スラグ中に還元用の炭素源を添加することにより還元し、鉄、リン、マンガン等の有価成分を溶銑中に回収することができる。 Moreover, in this invention, valuable components, such as iron, phosphorus, and manganese, in steelmaking slag can be collect | recovered by performing the reduction process of steelmaking slag in a molten state. Steelmaking slag contains a large amount of valuable metals such as iron, phosphorus and manganese in the form of oxides (FeO, MnO, P 2 O 5 etc.) in addition to CaO and SiO 2 . Therefore, when hot metal is used as a seed bath, the oxides of these valuable components are reduced by adding a carbon source for reduction into the steelmaking slag, and valuable components such as iron, phosphorus and manganese are reduced. It can be recovered in the hot metal.
特に、リンは、肥料原料等として用いられるため重要である。一般に、リンは鉄のもろさの原因となるため、通常は脱リン処理により溶銑中から取り除かれるが、本発明は、リンを一時的に種湯溶銑中に濃化させておき、その後高濃度のリンを含む溶銑を脱リンし、得られたスラグ中に高濃度の酸化リン(P2O5)として回収し、肥料原料等として資源化する目的で用いられる。 In particular, phosphorus is important because it is used as a fertilizer raw material. Generally, since phosphorus causes brittleness of iron, it is usually removed from the hot metal by dephosphorization treatment, but the present invention temporarily concentrates phosphorus in the seed hot water, and then high concentration. The hot metal containing phosphorus is dephosphorized, recovered as high-concentration phosphorus oxide (P 2 O 5 ) in the obtained slag, and used as a fertilizer raw material or the like.
また、例えば、同一の種湯溶銑を用いて本発明の還元処理を繰り返して行い、溶銑中のリン濃度を高めた後に脱リンを行うことにより、高濃度の酸化リンを含む脱リンスラグを生成することが可能である。このような脱リンスラグは、少量のスラグからリンを高効率で回収できる高品位のリン資源となる。 In addition, for example, by performing the reduction treatment of the present invention repeatedly using the same seed hot metal, and dephosphorizing after increasing the phosphorus concentration in the hot metal, dephosphorization slag containing high concentration phosphorous oxide is generated. It is possible. Such dephosphorization slag becomes a high-quality phosphorus resource capable of recovering phosphorus from a small amount of slag with high efficiency.
(種湯溶銑の役割)
また、本発明では、溶融状態の製鋼スラグを種湯としての溶銑が保持された反応容器に装入する。これにより、製鋼スラグの改質還元反応の際、溶融状態の製鋼スラグの顕熱だけでなく、種湯溶銑の顕熱を利用でき、吸熱反応である還元反応中に一旦溶融したスラグが溶融状態を維持することができる。その結果、上述したように、スラグ中のf・CaOの滓化を促進し、スラグの還元速度を維持し、かつ、COの脱泡速度を維持することもできる。ここで、溶銑が有する顕熱を利用することにより、還元反応(吸熱反応)中もスラグの溶融状態を維持するという観点からは、種湯溶銑の質量は、製鋼スラグの質量の1/4以上であることが好ましく、製鋼スラグと同質量以上であることがさらに好ましく、製鋼スラグの質量の1.5倍以上であることが最も好ましい。製鋼スラグの質量に対し、溶銑の質量が1/4未満である場合には、還元反応中にスラグの温度低下を招き、スラグの溶融状態を維持することが困難となるため、溶銑の質量が製鋼スラグの質量に対して1/4以上であることが好ましい。
(Role of seed hot metal)
In the present invention, the molten steelmaking slag is charged into a reaction vessel in which hot metal as seed hot water is held. As a result, in the reforming reduction reaction of steelmaking slag, not only the sensible heat of molten steelmaking slag but also the sensible heat of seed hot metal can be used, and the slag once melted during the reduction reaction, which is an endothermic reaction, is in a molten state Can be maintained. As a result, as described above, the hatching of f · CaO in the slag can be promoted, the reduction rate of the slag can be maintained, and the degassing rate of CO can also be maintained. Here, from the viewpoint of maintaining the molten state of the slag during the reduction reaction (endothermic reaction) by utilizing the sensible heat of the hot metal, the mass of the seed hot metal is ¼ or more of the mass of the steelmaking slag. It is preferable that it is the same mass or more as steelmaking slag, and it is most preferable that it is 1.5 times or more of the mass of steelmaking slag. When the mass of the hot metal is less than 1/4 with respect to the mass of the steelmaking slag, the temperature of the slag is reduced during the reduction reaction, and it becomes difficult to maintain the molten state of the slag. It is preferable that it is 1/4 or more with respect to the mass of steelmaking slag.
また、溶銑を種湯として使用することにより、還元反応のサイトとして溶銑/スラグ界面を利用することができる。製鋼スラグの還元反応は、スラグ/還元用炭素源界面よりも、主に溶銑/スラグ界面で進行する。言い換えると、還元反応速度はスラグ/還元用炭素源界面よりも、溶銑/スラグ界面で大きいので、溶銑を保持した容器内に製鋼スラグを装入することにより、溶銑/スラグ界面を還元反応サイトとして利用して、製鋼スラグの還元反応速度を大きくする(還元反応を促進する)ことができる。ここで、還元反応サイトとして溶銑/スラグ界面を利用した場合に、還元反応速度を最大化するために、還元反応界面積を最大化する観点からは、種湯として用いる溶銑の量は、少なくとも反応容器の底面全体を覆う量であることが好ましい。 Moreover, by using hot metal as seed hot water, the hot metal / slag interface can be used as a site for the reduction reaction. The reduction reaction of steelmaking slag proceeds mainly at the hot metal / slag interface rather than the slag / reducing carbon source interface. In other words, the reduction reaction rate is greater at the hot metal / slag interface than at the slag / reducing carbon source interface, so by introducing the steelmaking slag into a container holding the hot metal, the hot metal / slag interface is used as the reduction reaction site. By utilizing this, the reduction reaction rate of steelmaking slag can be increased (reduction reaction is promoted). Here, in the case where the hot metal / slag interface is used as the reduction reaction site, in order to maximize the reduction reaction rate, from the viewpoint of maximizing the reduction reaction interface area, the amount of hot metal used as the seed bath is at least the reaction It is preferable that the amount covers the entire bottom surface of the container.
さらに、溶銑を種湯として使用することにより、製鋼スラグ中の有価成分(鉄、リン、マンガン等)を種湯として用いた溶銑中に高効率で回収することができる。製鋼スラグ中のリンやマンガン等の有価金属の酸化物は、還元されて金属単体となり種湯溶銑中に移行する。種湯溶銑は、上述したように、還元反応界面積を最大化する観点から、少なくとも反応容器の底面全体を覆うために、反応容器内に多量に保持されている。したがって、製鋼スラグ中のリンやマンガン等の有価成分は、量の多い種湯溶銑に移行しても、種湯溶銑中の有価成分の濃度は低い状態であるので、製鋼スラグからの有価成分の移行速度、言い換えると、製鋼スラグ中の有価成分の酸化物の還元速度を、有価成分濃度が飽和に達するまで維持することができる。一方、種湯溶銑が少量である場合には、リンやマンガン等の有価成分の濃度が飽和しやすくなるため、有価成分の酸化物の還元速度は低下してしまう。 Furthermore, by using hot metal as the seed hot water, valuable components (iron, phosphorus, manganese, etc.) in the steelmaking slag can be recovered with high efficiency in the hot metal using the seed hot water. The valuable metal oxides such as phosphorus and manganese in the steelmaking slag are reduced to become a single metal and transferred to the seed hot metal. As described above, from the viewpoint of maximizing the reduction reaction interface area, the seed hot metal is retained in a large amount in the reaction vessel in order to cover at least the entire bottom surface of the reaction vessel. Therefore, even if valuable components such as phosphorus and manganese in steelmaking slag are transferred to a large amount of seeded hot metal, the concentration of valuable components in the seeded hot metal is low. The transition rate, in other words, the reduction rate of the valuable component oxide in the steelmaking slag can be maintained until the valuable component concentration reaches saturation. On the other hand, when the amount of the seed hot metal is small, the concentration of valuable components such as phosphorus and manganese is likely to be saturated, so that the reduction rate of the valuable component oxide is reduced.
(加熱手段)
本発明では、改質処理および還元処理を行う際に同一の処理温度を維持するために、加熱手段として加熱用バーナー等による加熱手段(以下、「バーナー加熱手段」という。)、または、燃焼用炭材を供給しながらランス等により酸素を吹き込むことによる加熱手段(以下、「酸素ガスを使用する加熱手段」という。)を使用することが好ましい。ここで、上記加熱用バーナーの燃料としては、例えば、重油、液化石油ガス(LPG)などを使用することができる。また、酸素ガスを使用する加熱手段の場合には、燃焼用炭材を燃焼させた際に発生する燃焼熱を利用して製鋼スラグを加熱する。燃焼用炭材は、製鋼スラグの還元処理に使用する還元用炭素源と同一の形態でも異なる形態でもよい。また、燃焼用炭材と還元用炭素源とは、その双方を同一の加熱手段、例えば、粉体溶射バーナーから供給してもよく、異なる加熱手段から、例えば、燃焼用炭材は粉体溶射バーナーから供給し、還元用炭素源は粉体溶射バーナーとは別のスラグ上面側に設置したパイプから供給してもよい。
(Heating means)
In the present invention, a heating means such as a heating burner (hereinafter referred to as “burner heating means”) or a combustion means is used as the heating means in order to maintain the same processing temperature during the reforming treatment and the reduction treatment. It is preferable to use a heating means (hereinafter referred to as “heating means using oxygen gas”) by blowing oxygen with a lance or the like while supplying the carbonaceous material. Here, as the fuel for the heating burner, for example, heavy oil, liquefied petroleum gas (LPG), or the like can be used. In the case of a heating means using oxygen gas, the steelmaking slag is heated using combustion heat generated when the combustion carbonaceous material is burned. The combustion carbonaceous material may be in the same form or different form from the reducing carbon source used for the reduction treatment of the steelmaking slag. Further, both the combustion carbon material and the reducing carbon source may be supplied from the same heating means, for example, a powder thermal spray burner, and from different heating means, for example, the combustion carbon material may be powder thermal sprayed. The carbon source for reduction may be supplied from a burner, and may be supplied from a pipe installed on the upper surface side of the slag different from the powder sprayed burner.
ここで、バーナー加熱手段と酸素ガスを使用する加熱手段のうち、詳しくは後述するように、高炉スラグの場合に生ずる黄水発生の問題を解消すべく、改質還元処理後の製鋼スラグ(以下、「改質スラグ」と記載する場合がある。)中の硫黄(S)濃度を0.7質量%とするためには、加熱手段として、酸素ガスを使用する加熱手段を用いることが好ましい。 Here, among the heating means using the burner heating means and oxygen gas, as will be described in detail later, in order to solve the problem of yellow water generation that occurs in the case of blast furnace slag, In order to make the sulfur (S) concentration in 0.7) mass%, it is preferable to use a heating means using oxygen gas as the heating means.
(ガス撹拌によるスラグの均熱化)
また、改質還元処理の際、上述したような加熱はスラグ上面側から行われるため、スラグ上面側では改質反応や還元反応が十分に進む一方で、スラグ下面側(溶銑側)ではスラグ上面側からの加熱の効果が及びにくいため、改質反応や還元反応が十分に進まないことがある。そこで、改質還元処理中の製鋼スラグを均熱化するため、製鋼スラグ中に上吹きランス等からガスの吹込みを行って、処理中のスラグを撹拌するようにしてもよい。このような撹拌に使用するガス種としては、例えば、アルゴンなどの不活性ガスを使用することができるが、スラグに燃焼用炭材が供給される場合には、撹拌用ガスとして酸素を含むガスを使用することにより、撹拌用の酸素含有ガスが燃焼用炭材を燃焼させることができるため、スラグ撹拌と同時にスラグ温度の維持を効率的に行うことができる。
(Soaking of slag by gas stirring)
Further, during the reforming and reducing treatment, the heating as described above is performed from the upper surface side of the slag, so that the reforming reaction and the reduction reaction sufficiently proceed on the upper surface side of the slag, while the upper surface of the slag is on the lower surface side of the slag (hot metal side). Since the effect of heating from the side is difficult to achieve, the reforming reaction or reduction reaction may not proceed sufficiently. Therefore, in order to equalize the steelmaking slag during the reforming reduction treatment, gas may be blown into the steelmaking slag from an upper blowing lance or the like to stir the slag being treated. As the gas species used for such stirring, for example, an inert gas such as argon can be used. However, when a combustion carbon material is supplied to the slag, a gas containing oxygen as the stirring gas. Since the oxygen-containing gas for stirring can burn the combustion carbonaceous material, the slag temperature can be efficiently maintained simultaneously with the slag stirring.
(SiO2含有改質材)
また、本発明において、SiO2含有改質材は、改質処理において、製鋼スラグの塩基度(CaO/SiO2の質量比)を低減するために、製鋼スラグに添加される。このようなSiO2含有改質材としては、ケイ酸を含有しているものであれば特に限定はされないが、SiO2含有量が50質量%以上のものが好ましく、例えば、石炭灰、ケイ砂などが例示できる。なお、SiO2含有改質材について、SiO2成分の残部は主にAl2O3成分である場合が多い。また、SiO2含有改質材のサイズについては、特に限定はされない。
(Modified material containing SiO 2 )
In the present invention, the SiO 2 -containing reforming material is added to the steelmaking slag in order to reduce the basicity of the steelmaking slag (CaO / SiO 2 mass ratio) in the reforming treatment. Such a SiO 2 -containing modifying material is not particularly limited as long as it contains silicic acid, but those having a SiO 2 content of 50% by mass or more are preferable. For example, coal ash, silica sand Etc. can be exemplified. In addition, with respect to the SiO 2 -containing modifier, the remainder of the SiO 2 component is often mainly an Al 2 O 3 component. Further, the size of the SiO 2 -containing modifier is not particularly limited.
ここで、本発明においては、改質還元処理後の製鋼スラグの塩基度が0.7以上となるように、SiO2含有改質材の添加量を調整することが必要となる。以下に、図1を参照しながら、改質還元処理後の製鋼スラグの塩基度を0.7以上とする理由について説明する。図1は、改質還元処理後の製鋼スラグの塩基度と圧縮強度(N/mm2)との関係の一例を示すグラフである。 Here, in the present invention, it is necessary to adjust the addition amount of the SiO 2 -containing modifier so that the basicity of the steelmaking slag after the reforming reduction treatment is 0.7 or more. Hereinafter, the reason why the basicity of the steelmaking slag after the reforming reduction treatment is set to 0.7 or more will be described with reference to FIG. FIG. 1 is a graph showing an example of the relationship between the basicity of steelmaking slag after the reforming reduction treatment and the compressive strength (N / mm 2 ).
本発明者らは、改質還元処理後の製鋼スラグの適正な塩基度を検討するために、以下のような実験を行った。 The present inventors conducted the following experiment in order to examine the appropriate basicity of the steelmaking slag after the reforming reduction treatment.
まず、種湯溶銑100tを保持する転炉型反応容器に、SiO2含有改質材として使用する5〜10mm径の石炭灰、Al2O3含有物質として使用する5〜20mm径に粉砕したアルミナ系耐火物屑、還元用炭素源として使用する10〜50mm径のコークス3.3tを事前に一括投入した。その後、溶銑予備処理スラグ20tを溶融状態のまま転炉型反応容器に装入した。なお、石炭灰の投入量は、塩基度を変化させた改質還元処理後のスラグを得るために変数とした。また、アルミナ系耐火物屑は、改質還元処理後のスラグ中のAl2O3濃度を15質量%にするために必要な投入量を石炭灰の投入量および溶銑予備処理スラグ組成から決定した。 First, 5 to 10 mm diameter coal ash used as a SiO 2 -containing modifier, and 5 to 20 mm diameter alumina used as an Al 2 O 3 containing substance in a converter reactor holding 100 t of hot metal seed 3.3 to 10 mm diameter coke 3.3t used as a system refractory scrap and a carbon source for reduction was charged in advance. Thereafter, the hot metal pretreatment slag 20t was charged into the converter reactor in a molten state. The input amount of coal ash was used as a variable in order to obtain slag after the reforming reduction treatment with changing basicity. In addition, for the alumina-based refractory waste, the amount required to make the Al 2 O 3 concentration in the slag after the reforming reduction treatment 15% by mass was determined from the amount of coal ash input and the hot metal pretreatment slag composition. .
また、コークスは、炭素分に換算して、転炉型反応容器に装入した溶銑予備処理スラグの質量100質量%に対して外数で15質量%となる添加量とした。 Moreover, coke was made into the addition amount which becomes 15 mass% in an external number with respect to 100 mass% of hot metal pretreatment slag charged into the converter reactor in conversion to carbon content.
スラグの装入後、上吹きランスより酸素を供給し、溶融改質還元処理を18分間行った。処理温度は1400℃〜1470℃で行い、処理中のスラグを常に溶融状態に維持した。なお、上吹き酸素による燃焼やスラグ中の酸化鉄分等の還元によって消費される炭素分を補うために、溶融改質還元処理中に、反応容器の上方から10〜50mm径のコークスを連続供給した。このときのコークスの供給速度については、溶融改質還元処理により発生する排ガス量Q(Nm3/h)および排ガス中のCO濃度およびCO2濃度(体積%)を連続的に測定し、この測定値に基づき、次式より決定した。なお、排ガス中のCO濃度およびCO2濃度は、反応容器に接続された排ガスダクトから排ガスをサンプリングし、質量分析計、赤外線ガス分析計、ガスクロマトグラフィ等の分析機器を用いて測定することができる。
コークス供給速度(kg/h)
=(%CO+%CO2)/100×Q/22.4×12/(コークス中の炭素割合)
(「%CO」及び「%CO2」は、それぞれ、排ガス中のCO濃度およびCO2濃度(体積%)を表す。)
After charging the slag, oxygen was supplied from the top blowing lance, and the melt reforming reduction treatment was performed for 18 minutes. The treatment temperature was 1400 ° C. to 1470 ° C., and the slag during the treatment was always kept in a molten state. In addition, 10-50 mm diameter coke was continuously supplied from the upper side of the reaction vessel during the melt reforming reduction treatment in order to supplement the carbon consumed by the combustion with the top blown oxygen and the reduction of the iron oxide in the slag. . Regarding the coke supply rate at this time, the amount Q (Nm 3 / h) of exhaust gas generated by the melt reforming reduction treatment and the CO concentration and CO 2 concentration (volume%) in the exhaust gas were continuously measured. Based on the value, it was determined from the following equation. The CO concentration and CO 2 concentration in the exhaust gas can be measured by sampling the exhaust gas from the exhaust gas duct connected to the reaction vessel and using an analytical instrument such as a mass spectrometer, an infrared gas analyzer, or a gas chromatography. .
Coke supply speed (kg / h)
= (% CO +% CO 2 ) /100×Q/22.4×12/ ( carbon ratio in the coke)
(“% CO” and “% CO 2 ” represent the CO concentration and CO 2 concentration (volume%) in the exhaust gas, respectively.)
溶融改質還元処理の終了後、処理後の改質スラグをスラグ鍋に排出し、凝固させた。 After completion of the melt reforming reduction treatment, the treated reforming slag was discharged into a slag pan and solidified.
なお、本実験におけるスラグ組成の分析方法としては、JIS K 0119に準拠して蛍光X線分析を行い、また、改質還元処理後の製鋼スラグの圧縮強度は、JIS A 1132に準拠して測定した。測定結果を下記表1に示す。この実験の結果、改質還元処理後の製鋼スラグの塩基度と圧縮強度(N/mm2)について、図1のような関係があることがわかった。 In addition, as an analysis method of the slag composition in this experiment, fluorescent X-ray analysis is performed according to JIS K 0119, and the compressive strength of the steelmaking slag after the reforming reduction treatment is measured according to JIS A 1132. did. The measurement results are shown in Table 1 below. As a result of this experiment, it was found that the basicity and compressive strength (N / mm 2 ) of the steelmaking slag after the reforming reduction treatment have a relationship as shown in FIG.
なお、CaO/SiO2以外のスラグ成分は、Al2O3=14〜16質量%、MgO=5〜7質量%、T.Fe=0.2〜0.5質量%、MnO=0.9〜1.5質量%であった。 Incidentally, CaO / slag components other than SiO 2 is, Al 2 O 3 = 14~16 wt%, MgO = 5 to 7 wt%, T. Fe = 0.2 to 0.5 mass% and MnO = 0.9 to 1.5 mass%.
本実験の結果、図1に示すように、改質還元処理後の製鋼スラグの塩基度が0.7未満となると、急激にスラグの圧縮強度が低下する傾向にあることがわかった。これは、改質還元処理後の製鋼スラグの塩基度が0.7未満であると、スラグの粘性が高く、改質還元処理終了後にスラグを反応容器から排出する際に還元用炭素源が巻き込まれた状態で排出され、スラグと炭素分とが分離せずに炭素分がスラグ中に残存し、この残存した炭素の粒子が亀裂等の起点となるため、スラグの強度が低下するものと推測される。 As a result of this experiment, as shown in FIG. 1, it was found that when the basicity of the steelmaking slag after the reforming reduction treatment is less than 0.7, the compressive strength of the slag tends to be abruptly lowered. This is because, when the basicity of the steelmaking slag after the reforming and reducing treatment is less than 0.7, the viscosity of the slag is high, and when the slag is discharged from the reaction vessel after the reforming and reducing treatment is completed, a reducing carbon source is involved. It is estimated that the strength of the slag is reduced because the carbon remains in the slag without separation of the slag and carbon, and the remaining carbon particles become the starting point of cracks etc. Is done.
そこで、本発明に係る製鋼スラグの処理方法においては、改質還元処理の製鋼スラグの塩基度が0.7以上の範囲となるように、SiO2含有改質材の添加することとした。 Therefore, in the steelmaking slag treatment method according to the present invention, the SiO 2 -containing modifier is added so that the basicity of the steelmaking slag in the reforming reduction treatment is in the range of 0.7 or more.
本発明に係る製鋼スラグの溶融改質還元処理方法においては、図1に示すように、改質スラグの強度を高くできるため、例えば、上層路盤材、コンクリート用骨材、石材原料(割栗石等)、砥砂等の高級用途に十分使用可能な品質の製鋼スラグを得ることができる。 As shown in FIG. 1, in the method for melt reforming and reducing steelmaking slag according to the present invention, the strength of the reformed slag can be increased. For example, upper-layer roadbed materials, concrete aggregates, stone raw materials (wariishi stone, etc.) ), A steelmaking slag having a quality that can be sufficiently used for high-grade applications such as abrasive sand can be obtained.
また、改質還元処理後の製鋼スラグの塩基度が1.5以下となるように、SiO2含有改質材の添加量を調整することが好ましい。製鋼スラグの塩基度が1.5を超えると、スラグの融点が上昇し、スラグの粘度が高くなることから、スラグ中のf・CaOとSiO2含有改質材中のSiO2との反応が十分に進行せず、安定してf・CaOを減少させることができにくくなるためである。さらに、塩基度がより低い方が改質反応をより確実に行うことができることから、改質還元処理後の製鋼スラグの塩基度が1.4以下となるように、SiO2含有改質材の添加量を調整することがより好ましい。 Further, as the basicity of the steel slag after modification reduction treatment is 1.5 or less, it is preferable to adjust the addition amount of SiO 2 containing modifier. When basicity of the steel slag exceeds 1.5, the melting point of the slag is increased, the reaction from the viscosity of the slag is increased, the SiO 2 of the f · CaO and SiO 2 containing modifier in slag This is because it does not proceed sufficiently and it becomes difficult to stably reduce f · CaO. Furthermore, since the reforming reaction can be performed more reliably when the basicity is lower, the basicity of the SiO 2 -containing reforming material is adjusted so that the basicity of the steelmaking slag after the reforming reduction treatment is 1.4 or less. It is more preferable to adjust the addition amount.
(Al2O3含有物質)
また、本発明に係る製鋼スラグの処理方法では、溶融状態の製鋼スラグにAl2O3含有物質を添加することが必要である。このようなAl2O3含有物質としては、アルミナを含有しているものであれば特に限定はされないが、例えば、石炭灰、ボーキサイト、赤泥、アルミナ耐火物屑などが例示できる。本発明者らの検討によれば、Al2O3含有物質の添加により、改質還元処理において、製鋼スラグの粘度を低下させ、これにより、製鋼スラグ中の酸化鉄やP2O5等の酸化物の還元反応の反応速度を向上させて、製鋼スラグの改質還元処理に要する時間を短縮するために添加される。
(Al 2 O 3 containing material)
In the steelmaking slag treatment method according to the present invention, it is necessary to add an Al 2 O 3 -containing material to the molten steelmaking slag. Such an Al 2 O 3 -containing substance is not particularly limited as long as it contains alumina, and examples thereof include coal ash, bauxite, red mud, and alumina refractory waste. According to the study by the present inventors, the viscosity of the steelmaking slag is reduced in the reforming reduction treatment by adding the Al 2 O 3 -containing substance, and thereby iron oxide, P 2 O 5, etc. in the steelmaking slag can be reduced. It is added to improve the reaction rate of the oxide reduction reaction and to shorten the time required for the reforming reduction treatment of the steelmaking slag.
ただし、Al2O3の濃度が高くなり過ぎると、改質還元処理中のスラグの粘度が再び上昇し、逆に還元速度を低下させてしまうことも、本発明者らの検討により判明した。従って、Al2O3の濃度が高くなり過ぎると、改質還元処理に要する時間が増大し、これに伴い、加熱等のためのエネルギー原単位が増大するとともに、CO2の発生量も増加してしまう、という問題を生ずる。さらには、製鋼スラグ中の酸化物の還元速度が低下するために、T.Feを十分に低下させることができずにスラグ製品としての特性(吸水率等)が悪化したり、P2O5等の有価金属の回収量も低下したりする、という問題も生ずる。また、Al2O3の濃度が高くなり過ぎる場合、改質還元処理の際に添加した還元用炭素源中の炭素分のうち、改質還元処理後の製鋼スラグ中に残留してしまう炭素分が多く、この炭素分とスラグとの分離が不完全となるため、処理後のスラグの強度の低下を招く、という問題もある。 However, it has also been found by the present inventors that if the concentration of Al 2 O 3 becomes too high, the viscosity of the slag during the reforming and reduction treatment increases again, and conversely reduces the reduction rate. Therefore, if the concentration of Al 2 O 3 becomes too high, the time required for the reforming reduction treatment increases, and accordingly, the energy intensity for heating and the like increases and the amount of CO 2 generated also increases. The problem that it ends up occurs. Furthermore, since the reduction rate of the oxide in the steelmaking slag is reduced, T.I. There are also problems that Fe cannot be sufficiently reduced and characteristics as a slag product (water absorption rate, etc.) are deteriorated, and the amount of valuable metals such as P 2 O 5 is also reduced. Moreover, when the concentration of Al 2 O 3 becomes too high, the carbon content remaining in the steelmaking slag after the reforming reduction treatment among the carbon content in the reducing carbon source added during the reforming reduction treatment. In many cases, the separation between the carbon and slag is incomplete, which causes a problem that the strength of the slag after the treatment is reduced.
そこで、本発明者らは、Al2O3含有物質の適切な添加量について検討するために、以下のような実験を行った。本実験では、改質還元処理中における製鋼スラグ中のAl2O3濃度(質量%)と酸化鉄(FeO)の還元速度との関係、及び、改質還元処理中における製鋼スラグ中のAl2O3濃度(質量%)と改質還元処理後の製鋼スラグの圧縮強度(N/mm2)との関係を調査した。 Therefore, the present inventors conducted the following experiment in order to examine an appropriate addition amount of the Al 2 O 3 -containing substance. In this experiment, the relationship between the Al 2 O 3 concentration (mass%) in the steelmaking slag during the reforming reduction treatment and the reduction rate of iron oxide (FeO), and the Al 2 in the steelmaking slag during the reforming reduction treatment. The relationship between the O 3 concentration (mass%) and the compressive strength (N / mm 2 ) of the steelmaking slag after the reforming reduction treatment was investigated.
1)FeO還元速度の評価
誘導溶解炉にて15kgの溶銑を溶解した後、2kgの溶銑予備処理スラグを添加し、FeO量の経時変化を調査した。本実験においては、還元用の炭素源は添加せず、溶銑中のC(炭素分)による還元速度で評価した。また、本実験では、溶解炉内への熱供給は誘導加熱によって行い、処理温度は1450℃で一定に保持した。また、浴内にArガスを吹き込むことにより攪拌を行った。
1) Evaluation of FeO reduction rate After melting 15 kg of hot metal in an induction melting furnace, 2 kg of hot metal pretreatment slag was added, and the change with time in the amount of FeO was investigated. In this experiment, the carbon source for reduction was not added, and the reduction rate by C (carbon content) in the hot metal was evaluated. In this experiment, the heat supply into the melting furnace was performed by induction heating, and the treatment temperature was kept constant at 1450 ° C. Further, stirring was performed by blowing Ar gas into the bath.
本実験で使用した溶銑予備処理スラグは、塩基度(=CaO/SiO2)を1.2、MgO濃度を6質量%、FeO濃度を15質量%と固定し、Al2O3濃度のみを2質量%〜42質量%に変化させた。 The hot metal pretreatment slag used in this experiment has a basicity (= CaO / SiO 2 ) of 1.2, an MgO concentration of 6% by mass, an FeO concentration of 15% by mass, and an Al 2 O 3 concentration of 2 only. The mass was changed from mass% to 42 mass%.
溶銑予備処理スラグ添加後から2分間隔でスラグをサンプリングし、分析を行った。FeO濃度と処理時間tとの関係は、次式に示すように1次反応で整理できた。
−d[FeO]/dt = k・t
After the hot metal pretreatment slag was added, slag was sampled at an interval of 2 minutes and analyzed. The relationship between the FeO concentration and the treatment time t could be arranged by a primary reaction as shown in the following equation.
−d [FeO] / dt = k · t
ここで、kは反応速度定数である。また、Al2O3濃度が7質量%〜20質量%のときのFeOの還元反応の反応速度定数はほぼ一定値をとった。そこで、この反応速度定数の値を基準として、7%未満、20%超過の場合の還元速度を評価した。 Here, k is a reaction rate constant. Further, the reaction rate constant of the reduction reaction of FeO when the Al 2 O 3 concentration was 7% by mass to 20% by mass was almost constant. Therefore, the reduction rate was evaluated when the value of the reaction rate constant was less than 7% and more than 20%.
2)圧縮強度の評価
種湯溶銑100tを保持する転炉型反応容器に、SiO2含有改質材として使用する5〜10mm径の石炭灰2t、Al2O3含有物質として使用する5〜20mm径に粉砕したアルミナ系耐火物屑、還元用炭素源として使用する10〜50mm径のコークス3.3tを事前に一括投入した。その後、溶銑予備処理スラグ20tを溶融状態のまま転炉型反応容器に装入した。なお、石炭灰の投入量は、転炉型反応容器に装入する前の溶銑予備処理スラグを採取し、蛍光X線分析装置にて組成を分析し、目標とするCaO/SiO2の比1.2とするのに必要なSiO2量を算出することにより決定した。また、アルミナ系耐火物屑は、改質還元処理後のスラグ中のAl2O3濃度を変化させるため、変数とした。改質還元処理後のAl2O3濃度として5質量%〜42質量%に変化させた。
2) Evaluation of compressive strength 5 to 10 mm of coal ash 2t used as a SiO 2 -containing modifier, 5 to 20 mm used as an Al 2 O 3 -containing substance, in a converter reactor holding 100 t of seed hot metal Alumina-based refractory scraps crushed to a diameter and coke 3.3 t having a diameter of 10 to 50 mm used as a carbon source for reduction were charged in advance. Thereafter, the hot metal pretreatment slag 20t was charged into the converter reactor in a molten state. The amount of coal ash to be charged is obtained by collecting hot metal pretreatment slag before charging into a converter reactor, analyzing the composition with a fluorescent X-ray analyzer, and setting a target CaO / SiO 2 ratio of 1 It was determined by calculating the amount of SiO 2 required to obtain. Alumina-based refractory waste is a variable because it changes the concentration of Al 2 O 3 in the slag after the reforming reduction treatment. The Al 2 O 3 concentration after the reforming reduction treatment was changed from 5% by mass to 42% by mass.
また、コークスは、炭素分で転炉型反応容器に装入した溶銑予備処理スラグの質量100質量%に対して外数で15質量%となる添加量とした。 Moreover, coke was made into the addition amount which becomes 15 mass% in an external number with respect to 100 mass% of the hot metal pretreatment slag with which the carbon content was charged to the converter reactor.
スラグの装入後、上吹きランスより酸素を供給し、溶融改質還元処理を18分間行った。処理温度は1400℃〜1470℃で行い、処理中のスラグを常に溶融状態に維持した。なお、上吹き酸素による燃焼やスラグ中の酸化鉄分等の還元によって消費される炭素分を補うために、溶融改質還元処理中に、反応容器の上方から10〜50mm径のコークスを連続供給した。このときのコークスの供給速度については、溶融改質還元処理により発生する排ガス量Q(Nm3/h)および排ガス中のCO濃度およびCO2濃度(体積%)を連続的に測定し、この測定値に基づき、次式より決定した。
コークス供給速度(kg/h)
=(%CO+%CO2)/100×Q/22.4×12/(コークス中の炭素割合)
(「%CO」及び「%CO2」は、それぞれ、排ガス中のCO濃度およびCO2濃度(体積%)を表す。)
After charging the slag, oxygen was supplied from the top blowing lance, and the melt reforming reduction treatment was performed for 18 minutes. The treatment temperature was 1400 ° C. to 1470 ° C., and the slag during the treatment was always kept in a molten state. In addition, 10-50 mm diameter coke was continuously supplied from the upper side of the reaction vessel during the melt reforming reduction treatment in order to supplement the carbon consumed by the combustion with the top blown oxygen and the reduction of the iron oxide in the slag. . Regarding the coke supply rate at this time, the amount Q (Nm 3 / h) of exhaust gas generated by the melt reforming reduction treatment and the CO concentration and CO 2 concentration (volume%) in the exhaust gas were continuously measured. Based on the value, it was determined from the following equation.
Coke supply speed (kg / h)
= (% CO +% CO 2 ) /100×Q/22.4×12/ ( carbon ratio in the coke)
(“% CO” and “% CO 2 ” represent the CO concentration and CO 2 concentration (volume%) in the exhaust gas, respectively.)
溶融改質還元処理の終了後、処理後の改質スラグをスラグ鍋に排出し、凝固させた。 After completion of the melt reforming reduction treatment, the treated reforming slag was discharged into a slag pan and solidified.
ここで、本実験におけるスラグ組成の分析方法としては、JIS K 0119に準拠して蛍光X線分析を行った。また、FeOの還元速度としては、Al2O3濃度が7質量%〜20質量%のときのFeOの還元速度を1とした場合の還元速度の相対値である還元速度指数を用いた。さらに、改質還元処理後の製鋼スラグの圧縮強度は、JIS A 1132に準拠して測定した。測定結果を下記表2および表3に示す。 Here, as an analysis method of the slag composition in this experiment, fluorescent X-ray analysis was performed in accordance with JIS K 0119. Further, as the reduction rate of FeO, a reduction rate index, which is a relative value of the reduction rate when the reduction rate of FeO when the Al 2 O 3 concentration is 7% by mass to 20% by mass, is used. Furthermore, the compressive strength of the steelmaking slag after the reforming reduction treatment was measured in accordance with JIS A1132. The measurement results are shown in Table 2 and Table 3 below.
本実験の結果、改質還元処理中における製鋼スラグ中のAl2O3濃度(質量%)と酸化鉄(FeO)の還元速度との関係について、図2のような関係があり、改質還元処理中における製鋼スラグ中のAl2O3濃度(質量%)と改質還元処理後の製鋼スラグの圧縮強度(N/mm2)との関係について、図3のような関係があることがわかった。なお、図2は、改質還元処理中における製鋼スラグ中のAl2O3濃度(質量%)と酸化鉄(FeO)の還元速度との関係の一例を示すグラフである。図3は、改質還元処理中における製鋼スラグ中のAl2O3濃度(質量%)と改質還元処理後の製鋼スラグの圧縮強度(N/mm2)との関係の一例を示すグラフである。 As a result of this experiment, the relationship between the Al 2 O 3 concentration (mass%) in the steelmaking slag during the reforming reduction treatment and the reduction rate of iron oxide (FeO) is as shown in FIG. 3 shows that the relationship between the Al 2 O 3 concentration (mass%) in the steelmaking slag during the treatment and the compressive strength (N / mm 2 ) of the steelmaking slag after the reforming reduction treatment is as shown in FIG. It was. FIG. 2 is a graph showing an example of the relationship between the Al 2 O 3 concentration (% by mass) in the steelmaking slag during the reforming reduction treatment and the reduction rate of iron oxide (FeO). FIG. 3 is a graph showing an example of the relationship between the Al 2 O 3 concentration (mass%) in the steelmaking slag during the reforming reduction treatment and the compressive strength (N / mm 2 ) of the steelmaking slag after the reforming reduction treatment. is there.
まず、図2に示すように、FeOの還元速度については、改質還元処理中における製鋼スラグ中のAl2O3濃度が高くなるに従い、FeOの還元速度も高くなっていき、改質還元処理中における製鋼スラグ中のAl2O3濃度が7質量%以上20質量%以下の範囲でFeOの還元速度が一定となり、改質還元処理中における製鋼スラグ中のAl2O3濃度が20質量%を超えると、FeOの還元速度が低下する傾向にあることがわかった。 First, as shown in FIG. 2, with respect to the reduction rate of FeO, as the Al 2 O 3 concentration in the steelmaking slag during the reforming reduction treatment increases, the reduction rate of FeO also increases, and the reforming reduction treatment The reduction rate of FeO is constant when the Al 2 O 3 concentration in the steelmaking slag is 7 mass% or more and 20 mass% or less, and the Al 2 O 3 concentration in the steelmaking slag during the reforming reduction treatment is 20 mass%. It has been found that the reduction rate of FeO tends to decrease when the amount exceeds.
改質還元処理中における製鋼スラグ中のAl2O3濃度とFeOの還元速度との関係が上記のような傾向を示すのは、Al2O3濃度が7質量%以上20質量%以下の範囲においては、スラグの粘度が十分に低下し、FeOの還元反応が促進されるためであると考えられる。より具体的には、上述したように、種湯溶銑を使用した場合には、製鋼スラグの還元反応の反応サイトは、主に、溶銑/スラグ界面となるが、スラグの粘度が高いと、スラグ中のFeOの高い還元反応サイトである溶銑/スラグ界面への移動が妨げられる。従って、Al2O3濃度が7質量%以上20質量%以下の範囲にあり、スラグの粘度が十分に低い場合には、スラグ中のFeOの反応サイトへの到達が早くなるため、FeOの還元速度も速くなる。なお、ここでは、FeOのみの還元速度について見ているが、P2O5等の他の酸化物についても同様のことが言える。 The relationship between the Al 2 O 3 concentration in the steelmaking slag during the reforming reduction treatment and the reduction rate of FeO shows the above-mentioned tendency because the Al 2 O 3 concentration is in the range of 7% by mass to 20% by mass. Is considered to be because the viscosity of the slag is sufficiently lowered and the reduction reaction of FeO is promoted. More specifically, as described above, when the seed hot metal is used, the reaction site of the steelmaking slag reduction reaction is mainly the hot metal / slag interface, but when the viscosity of the slag is high, the slag Movement to the hot metal / slag interface, which is a high reduction reaction site of FeO, is prevented. Accordingly, when the Al 2 O 3 concentration is in the range of 7% by mass or more and 20% by mass or less and the viscosity of the slag is sufficiently low, the FeO in the slag reaches the reaction site faster, so the reduction of the FeO Speed will also increase. Here, the reduction rate of only FeO is seen, but the same can be said for other oxides such as P 2 O 5 .
また、図3に示すように、改質還元処理後の製鋼スラグの圧縮強度については、改質還元処理中における製鋼スラグ中のAl2O3濃度が高くなるに従い、圧縮強度も高くなっていき、改質還元処理中における製鋼スラグ中のAl2O3濃度が7質量%以上20質量%以下の範囲で圧縮強度が一定となり、改質還元処理中における製鋼スラグ中のAl2O3濃度が20質量%を超えると、圧縮強度が低下する傾向にあることがわかった。 Further, as shown in FIG. 3, the compressive strength of the steelmaking slag after the reforming and reducing treatment increases as the Al 2 O 3 concentration in the steelmaking slag during the reforming and reducing treatment increases. , the concentration of Al 2 O 3 is compressed in a range of 20 wt% or less 7 mass% or more intensity in steelmaking slag in the reforming reduction treatment is constant, the Al 2 O 3 concentration in the steelmaking slag in the reforming reduction treatment When it exceeded 20 mass%, it turned out that it exists in the tendency for compressive strength to fall.
改質還元処理中における製鋼スラグ中のAl2O3濃度と処理後のスラグの圧縮強度との関係が上記のような傾向を示すのは、Al2O3濃度が7質量%以上20質量%以下の範囲においては、スラグの粘度が十分に低いので、改質還元処理の際に添加した還元用炭素源中の炭素分のうち、改質還元処理後の製鋼スラグ中に残留する炭素分が少なく、この炭素分がスラグから分離できるためであると考えられる。 The relationship between the Al 2 O 3 concentration in the steelmaking slag during the reforming and reduction treatment and the compressive strength of the slag after the treatment shows the above-described tendency because the Al 2 O 3 concentration is 7% by mass or more and 20% by mass. In the following range, since the viscosity of the slag is sufficiently low, the carbon content remaining in the steelmaking slag after the reforming reduction treatment out of the carbon content in the reducing carbon source added during the reforming reduction treatment It is thought that this is because the carbon content can be separated from the slag.
なお、Al2O3濃度が7質量%以上20質量%以下の範囲において、FeOの還元速度および製鋼スラグの圧縮強度が一定となっているのは、この濃度範囲でスラグの粘度が一定となるためである。 It should be noted that the reduction rate of FeO and the compressive strength of steelmaking slag are constant when the Al 2 O 3 concentration is in the range of 7% by mass or more and 20% by mass or less. The slag viscosity is constant in this concentration range. Because.
また、製鋼スラグ中の炭素分とスラグとの分離は、通常は、溶融状態の処理後の改質スラグ中で炭素分を浮上させることにより行う。このとき、処理後の改質スラグの粘度が高いと、炭素分の浮上が妨げられるため、還元剤としての炭素分とスラグとの分離が不完全となる場合がある。また、処理後の改質スラグ中に残留する炭素分が多いと、その浮上に時間がかかるために、その間の温度低下によりスラグの粘度が上昇し、還元剤としての炭素分とスラグとの分離が不完全となる場合がある。 Moreover, the separation of the carbon content in the steelmaking slag and the slag is usually carried out by floating the carbon content in the modified slag after the treatment in the molten state. At this time, if the viscosity of the modified slag after the treatment is high, the floating of the carbon content is hindered, so that the separation of the carbon content and the slag as the reducing agent may be incomplete. In addition, if there is a large amount of carbon remaining in the modified slag after treatment, it takes time to float, so the viscosity of the slag rises due to the temperature drop during that time, and separation of the carbon and slag as the reducing agent May be incomplete.
このように、改質還元処理中における製鋼スラグ中のAl2O3濃度が7質量%未満であると、スラグの粘度が高く、スラグ中の酸化鉄やP2O5等の酸化物の還元速度が遅くなるために、改質還元処理に要する時間が長くなり、生産効率が低下する。一方、改質還元処理中における製鋼スラグ中のAl2O3濃度が20質量%を超えると、一旦低下したスラグの粘度が再び高くなり、スラグ中の酸化鉄やP2O5等の酸化物の還元速度が遅くなるために、改質還元処理に要する時間が長くなり、生産効率が低下する。また、改質還元処理中における製鋼スラグ中のAl2O3濃度が20質量%を超える場合には、改質還元処理後の製鋼スラグ中に還元剤として添加した炭素分が残留しやすくなるため、処理後の改質スラグの強度が低下する。 Thus, when the Al 2 O 3 concentration in the steelmaking slag during the reforming reduction treatment is less than 7% by mass, the viscosity of the slag is high, and the reduction of oxides such as iron oxide and P 2 O 5 in the slag is performed. Since the speed becomes slow, the time required for the reforming and reducing process becomes long, and the production efficiency decreases. On the other hand, when the Al 2 O 3 concentration in the steelmaking slag during the reforming reduction treatment exceeds 20% by mass, the viscosity of the slag once lowered is increased again, and oxides such as iron oxide and P 2 O 5 in the slag Since the reduction rate of is slowed down, the time required for the reforming reduction treatment becomes longer and the production efficiency is lowered. In addition, when the Al 2 O 3 concentration in the steelmaking slag during the reforming reduction treatment exceeds 20% by mass, carbon added as a reducing agent tends to remain in the steelmaking slag after the reforming reduction treatment. , The strength of the modified slag after processing is reduced.
そこで、本発明に係る製鋼スラグの処理方法においては、改質還元処理中における製鋼スラグ中のFeO等の還元速度を向上させ、かつ、改質還元処理により緻密で強度の高い改質された製鋼スラグを得るために、改質還元処理中を通じて、製鋼スラグ中のAl2O3濃度が7質量%以上20質量%以下となるように、Al2O3含有物質を添加することとした。また、Al2O3含有物質の添加量の下限値について、FeO等の還元速度の向上効果および改質スラグの強度の向上効果をより確実に奏するようにするためには、改質還元処理中を通じて、製鋼スラグ中のAl2O3濃度が8質量%以上となるように添加することが好ましく、10質量%以上となるように添加することがさらに好ましい。一方、Al2O3含有物質の添加量の上限値について、FeO等の還元速度の向上効果および改質スラグの強度の向上効果を維持しながら、よりコストを低減させるという観点から、改質還元処理中を通じて、製鋼スラグ中のAl2O3濃度が19質量%以下となるように添加することが好ましく、18質量%以下となるように添加することがさらに好ましい。 Therefore, in the steelmaking slag treatment method according to the present invention, the steelmaking slag is improved in the reduction rate such as FeO in the steelmaking slag during the reforming reduction treatment, and is refined and high in strength by the reforming reduction treatment. In order to obtain slag, it was decided to add the Al 2 O 3 -containing material so that the Al 2 O 3 concentration in the steelmaking slag was 7% by mass or more and 20% by mass or less throughout the reforming and reducing treatment. In order to more reliably achieve the effect of improving the reduction rate of FeO or the like and the effect of improving the strength of the reformed slag, the lower limit of the amount of the Al 2 O 3 -containing substance is not improved. Through addition, it is preferable to add so that the Al 2 O 3 concentration in the steelmaking slag is 8% by mass or more, and it is more preferable to add it to be 10% by mass or more. On the other hand, with respect to the upper limit of the addition amount of the Al 2 O 3 -containing substance, from the viewpoint of reducing costs while maintaining the effect of improving the reduction rate of FeO and the like and the effect of improving the strength of the modified slag, Throughout the treatment, it is preferably added so that the Al 2 O 3 concentration in the steelmaking slag is 19% by mass or less, and more preferably 18% by mass or less.
なお、上記SiO2含有改質材として石炭灰を使用する場合には、石炭灰中にAl2O3が含有されていることから、SiO2含有改質材として添加した石炭灰の量を考慮して、すなわち、SiO2含有改質材として添加した石炭灰中に含有されるAl2O3の量を差し引いて、添加するAl2O3含有物質の添加量を決定する必要がある。 In the case of using coal ash as the SiO 2 content modifier, since the Al 2 O 3 is contained in the coal ash, considering the amount of coal ash was added as a SiO 2 content modifier That is, it is necessary to subtract the amount of Al 2 O 3 contained in the coal ash added as the SiO 2 -containing modifier and determine the amount of the Al 2 O 3 -containing material to be added.
ちなみに、Al2O3含有物質添加の初期段階では、製鋼スラグ中のAl2O3濃度が7質量%以上20質量%以下に達していない時期が不可避的に生じるが、このような時期が短時間であり、この程度であれば、改質還元処理中を通じて、7質量%以上20質量%以下のAl2O3含有物質を添加したものとみなすことができる。 Incidentally, at the initial stage of addition of the Al 2 O 3 containing substance, a time when the Al 2 O 3 concentration in the steelmaking slag does not reach 7% by mass or more and 20% by mass or less inevitably occurs, but such a time is short. the time, if this degree, it can be assumed that throughout the reforming reduction treatment, was added 20 wt% or less 7 mass% or more Al 2 O 3 containing materials.
(還元用炭素源および燃焼用炭材)
本発明において、以上説明したような還元処理のために使用する還元用炭素源や燃焼用炭素源としては、主にコークスを使用することができるが、これには限られず、例えば、廃プラスチック、バイオマス、パルプ屑等の炭素質廃棄物などを使用することもできる。かかる炭素質廃棄物は、還元用炭素源または燃焼用炭素源のいずれか一方として使用してもよく、還元用炭素源および燃焼用炭素源の双方に使用してもよい。
(Reduction carbon source and combustion carbon)
In the present invention, as a reducing carbon source and a combustion carbon source used for the reduction treatment as described above, coke can be mainly used, but is not limited thereto, for example, waste plastic, Carbonaceous waste such as biomass and pulp waste can also be used. Such carbonaceous waste may be used as either a reducing carbon source or a burning carbon source, or may be used as both a reducing carbon source and a burning carbon source.
[本発明に係る改質スラグについて]
以上、本発明に係る製鋼スラグの処理方法について詳細に説明したが、続いて、上述した改質還元処理により得られる本発明に係る改質スラグについて詳細に説明する。
[Reformed slag according to the present invention]
Although the steel slag treatment method according to the present invention has been described in detail above, the modified slag according to the present invention obtained by the above-described reforming reduction process will be described in detail.
本発明に係る改質スラグは、製鋼スラグを加熱手段で加熱しながら、製鋼スラグにSiO2含有改質材および還元用炭素源を添加し、製鋼スラグを溶融改質還元処理して得られるものであり、かつ、得られたスラグ中の組成として、下記の(i)及び(ii)の条件を少なくとも満たすものである。
(i)Al2O3濃度が7質量%以上20質量%以下
(ii)塩基度が0.7以上
The reformed slag according to the present invention is obtained by adding a SiO 2 -containing reforming material and a reducing carbon source to the steelmaking slag while heating the steelmaking slag with a heating means, and subjecting the steelmaking slag to a melt reforming reduction treatment. In addition, the composition in the obtained slag satisfies at least the following conditions (i) and (ii).
(I) Al 2 O 3 concentration is 7% by mass or more and 20% by mass or less (ii) Basicity is 0.7 or more
まず、製鋼スラグの種類、加熱手段、SiO2含有改質材、還元用炭素源等については、上述したとおりであるので、ここでは詳細な説明を省略する。 First, the type of steelmaking slag, the heating means, the SiO 2 -containing reforming material, the reducing carbon source, and the like are as described above, and thus detailed description thereof is omitted here.
(改質スラグの組成)
<Al2O3濃度について>
また、上記(i)の条件については、Al2O3濃度が7質量%未満であると、スラグの粘度が高く、スラグ中の酸化鉄やP2O5等の酸化物の還元速度が遅くなるために、改質還元処理に要する時間が長くなり、生産効率が低下するため、Al2O3濃度を7質量%以上とした。一方、Al2O3濃度が20質量%を超えると、一旦低下したスラグの粘度が再び高くなり、スラグ中の酸化鉄やP2O5等の酸化物の還元速度が遅くなるために、改質還元処理に要する時間が長くなり、生産効率が低下するとともに、改質還元処理後の製鋼スラグ中に還元剤として添加した炭素分が残留しやすくなるため、処理後の改質スラグの強度が低下するため、Al2O3濃度を20質量%以下とした。また、Al2O3濃度の下限値について、FeO等の還元速度の向上効果および改質スラグの強度の向上効果をより確実に奏するようにするためには、改質スラグ中のAl2O3濃度が8質量%以上であることが好ましく、10質量%以上であることがさらに好ましい。一方、Al2O3濃度の上限値について、FeO等の還元速度の向上効果および改質スラグの強度の向上効果を維持しながら、よりコストを低減させるという観点から、改質スラグ中のAl2O3濃度が19質量%以下であることが好ましく、18質量%以下であることがさらに好ましい。
(Composition of modified slag)
<About Al 2 O 3 concentration>
As for the condition (i), when the Al 2 O 3 concentration is less than 7% by mass, the viscosity of the slag is high, and the reduction rate of oxides such as iron oxide and P 2 O 5 in the slag is slow. For this reason, the time required for the reforming reduction treatment becomes longer, and the production efficiency is lowered. Therefore, the Al 2 O 3 concentration is set to 7% by mass or more. On the other hand, when the Al 2 O 3 concentration exceeds 20% by mass, the viscosity of the slag once lowered is increased again, and the reduction rate of oxides such as iron oxide and P 2 O 5 in the slag is decreased. The time required for the quality reduction treatment becomes longer, the production efficiency decreases, and the carbon added as a reducing agent tends to remain in the steelmaking slag after the reforming reduction treatment. In order to decrease, the Al 2 O 3 concentration was set to 20% by mass or less. Further, Al 2 O 3 for the concentration of the lower limit value, in order to achieve the effect of improving the strength of the effect of improving and reforming slag reduction rate, such as FeO and more reliably, Al 2 O 3 in the reformed slag The concentration is preferably 8% by mass or more, and more preferably 10% by mass or more. On the other hand, the upper limit of the concentration of Al 2 O 3, while maintaining the effect of improving the strength of the effect and modifying slag reduction rate, such as FeO, from the viewpoint of reducing the more cost, in the reformed slag Al 2 The O 3 concentration is preferably 19% by mass or less, and more preferably 18% by mass or less.
<塩基度について>
また、上記(ii)の条件については、改質スラグが、上層路盤材、コンクリート用骨材、石材原料(割栗石等)、砥砂等の高級用途に十分使用可能な強度となるように、改質スラグの塩基度を0.7以上と規定した。
<About basicity>
In addition, with regard to the above condition (ii), the modified slag has a strength that can be sufficiently used for high-grade applications such as upper-layer roadbed materials, aggregates for concrete, stone raw materials (such as cracked stones), and abrasive sands. The basicity of the modified slag was defined as 0.7 or more.
なお、これらAl2O3濃度や塩基度の臨界値は、上述した実験の結果に基づいて規定されたものであり、ここではその詳細な説明を省略する。 The critical values of the Al 2 O 3 concentration and the basicity are defined based on the results of the above-described experiment, and detailed description thereof is omitted here.
<S濃度について>
また、本発明に係る改質スラグの組成としては、改質スラグ中のS濃度が0.7質量%以下であることが好ましく、0.6質量%以下であることがより好ましく、0.5質量%以下であることがさらに好ましい。このように、改質スラグ中のS濃度を0.7質量%以下とする組成は、本発明に係る改質スラグを得るための溶融改質還元処理の際に、加熱手段として酸素を使用する加熱手段を用いることにより実現することができる。
<About S concentration>
Further, as the composition of the modified slag according to the present invention, the S concentration in the modified slag is preferably 0.7% by mass or less, more preferably 0.6% by mass or less, More preferably, it is at most mass%. Thus, the composition in which the S concentration in the reformed slag is 0.7% by mass or less uses oxygen as a heating means in the melt reforming reduction process for obtaining the reformed slag according to the present invention. This can be realized by using a heating means.
ここで、上記改質還元処理の条件によっては、本発明に係る改質スラグの組成を、高炉において発生する高炉スラグと類似の組成とすることができる。ところで、高炉スラグは、その外観、組成、物性等の面から、セメント原料等の高級用途に使用することができるため、商品価値が高い。しかし、高炉スラグは、下記表4に示すように、スラグ中に硫黄(S)分を1質量%程度含んでいるため、高炉徐冷スラグでは、いわゆる黄水が発生する問題がある。すなわち、黄水は、高炉徐冷スラグ中のCaSが酸化して安定なCaSO4に変化する過程で発生した多硫化カルシウムCaSxが水に溶解した黄色の溶出水であり、高炉徐冷スラグは、製品として出荷する前にエージング処理を十分に行い、黄水の発生がないようにすることが必要とされている。 Here, depending on the conditions of the above-described reforming and reducing treatment, the composition of the reforming slag according to the present invention can be made similar to the composition of the blast furnace slag generated in the blast furnace. By the way, blast furnace slag has high commercial value because it can be used for high-grade applications such as cement raw materials in terms of appearance, composition, physical properties and the like. However, since the blast furnace slag contains about 1 mass% of sulfur (S) in the slag as shown in Table 4 below, the blast furnace slag has a problem that so-called yellow water is generated. That is, yellow water is yellow elution water in which calcium polysulfide CaS x generated in the process in which CaS in blast furnace slow cooling slag is oxidized to change into stable CaSO 4 is dissolved in water, and blast furnace slow cooling slag is Therefore, it is necessary to sufficiently perform an aging treatment before shipping as a product so that yellow water is not generated.
これに対して、本発明に係る改質スラグが、酸素を使用する加熱手段を用いた改質還元処理により得られたものである場合には、上記表4に示すように、改質スラグの組成を高炉スラグと類似の組成とすることができるとともに、加熱手段からの酸素によりスラグ中のSが酸化されてSOxとなって排ガスとしてスラグ中から除外されるため、スラグ中のS濃度が低下し、改質スラグ中のS濃度を0.7質量%以下とすることができる。このようにスラグ中のS濃度が低い場合には、黄水が発生しない。従って、本発明に係る改質スラグは、高炉スラグと類似の組成を有することができることから、セメント原料等の高級用途に使用でき、また、黄水の発生の懸念もないことから、高炉徐冷スラグで必要であったエージング処理も不要となる。なお、SOxを含む排ガスは、通常知られている排ガスの脱硫設備を用いた処理や、アルカリ水で洗浄した中和等が行われる。 On the other hand, when the reformed slag according to the present invention is obtained by reforming and reducing treatment using heating means using oxygen, as shown in Table 4 above, with the composition can be a composition similar to the blast furnace slag, because the S in the slag is removed from the slag as an exhaust gas becomes oxidized SO x by oxygen from the heating means, the S concentration in the slag The S concentration in the reformed slag can be reduced to 0.7% by mass or less. Thus, when the S concentration in the slag is low, yellow water is not generated. Therefore, the modified slag according to the present invention can have a composition similar to that of the blast furnace slag, and thus can be used for high-grade applications such as cement raw materials. The aging process required for the slag is also unnecessary. The exhaust gas containing SO x is subjected to treatment using a generally known exhaust gas desulfurization facility, neutralization by washing with alkaline water, or the like.
<T.Fe濃度について>
また、本発明に係る改質スラグの組成としては、改質スラグ中のT.Feの濃度が1質量%以下であることが好ましく、0.5質量%以下であることがより好ましい。ここで、「T.Feの濃度」とは、スラグ中に含まれるFeO、Fe2O3及び金属鉄の合計の濃度のことを意味する。T.Feの濃度が1質量%以下とすることにより、上述したように、COガスを主とする気泡の発生を抑制すること、スラグを白色化または透明化してスラグの高付加価値化を図ること等の効果が得られる。
<T. About Fe Concentration>
In addition, the composition of the modified slag according to the present invention includes T.I. The Fe concentration is preferably 1% by mass or less, and more preferably 0.5% by mass or less. Here, “T.Fe concentration” means the total concentration of FeO, Fe 2 O 3 and metallic iron contained in the slag. T. T. et al. By controlling the Fe concentration to 1% by mass or less, as described above, it is possible to suppress the generation of bubbles mainly composed of CO gas, whiten or transparentize the slag, and increase the added value of the slag. The effect is obtained.
<MgO濃度について>
また、本発明に係る改質スラグの組成としては、改質スラグ中のMgO濃度が15質量%以下であることが好ましい。MgO濃度が高過ぎると、MgOの体積膨張による影響(微小な亀裂や開気孔の発生等)が懸念されるためである。
<About MgO concentration>
In addition, as the composition of the modified slag according to the present invention, the MgO concentration in the modified slag is preferably 15% by mass or less. This is because if the MgO concentration is too high, there is a concern about the influence of the volume expansion of MgO (such as generation of minute cracks and open pores).
以下、実施例を用いて本発明をさらに具体的に説明する。なお、以下の実施例は、上述した本発明の実施の形態に基づいて、製鋼スラグの改質還元処理を行い、処理後のスラグ(改質スラグ)の成分や物性(吸水率及び圧縮強度)を評価したものである。 Hereinafter, the present invention will be described more specifically with reference to examples. In the following examples, based on the embodiment of the present invention described above, the steelmaking slag is reformed and reduced, and the components and physical properties (water absorption rate and compressive strength) of the treated slag (modified slag). Is evaluated.
(実施例1)
種湯溶銑100tを保持する転炉型反応容器に、SiO2含有改質材として使用する5〜10mm径の石炭灰2t、Al2O3含有物質として使用する5〜20mm径に粉砕したアルミナ系耐火物屑2t、還元用炭素源として使用する10〜50mm径のコークス3.3tを事前に一括投入した。その後、溶銑予備処理スラグ20tを溶融状態のまま転炉型反応容器に装入した。なお、石炭灰の投入量およびアルミナ系耐火物屑の投入量は、転炉型反応容器に装入する前の溶銑予備処理スラグを採取し、蛍光X線分析装置にて組成を分析し、目標とするCaO/SiO2の比1.2およびAl2O3濃度15質量%とするのに必要なSiO2量およびAl2O3量を算出することにより決定した。また、コークスは、炭素分で転炉型反応容器に装入した溶銑予備処理スラグの質量100質量%に対して外数で15質量%となる添加量とした。
Example 1
A converter-type reaction vessel for holding a Taneyu molten iron 100 t, alumina ground to 5~20mm diameter using coal ash 2t of 5~10mm diameter to be used as the SiO 2 content modifier, as Al 2 O 3 containing materials Refractory waste 2t and coke 3.3t having a diameter of 10 to 50 mm used as a carbon source for reduction were charged in advance. Thereafter, the hot metal pretreatment slag 20t was charged into the converter reactor in a molten state. The amount of coal ash and the amount of alumina refractory debris that were collected were collected from the hot metal pretreatment slag before being charged into the converter reactor, analyzed for the composition with a fluorescent X-ray analyzer, The ratio was determined by calculating the amount of SiO 2 and the amount of Al 2 O 3 required to obtain a CaO / SiO 2 ratio of 1.2 and an Al 2 O 3 concentration of 15% by mass. Moreover, coke was made into the addition amount which becomes 15 mass% in an external number with respect to 100 mass% of the hot metal pretreatment slag with which the carbon content was charged to the converter reactor.
スラグの装入後、上吹きランスより酸素を供給し、溶融改質還元処理を18分間行った。処理温度は1400℃〜1470℃で行い、処理中のスラグを常に溶融状態に維持した。なお、上吹き酸素による燃焼やスラグ中の酸化鉄分等の還元によって消費される炭素分を補うために、溶融改質還元処理中に、反応容器の上方から10〜50mm径のコークスを連続供給した。このときのコークスの供給速度については、溶融改質還元処理により発生する排ガス量Q(Nm3/h)および排ガス中のCO濃度およびCO2濃度(体積%)を連続的に測定し、この測定値に基づき、次式より決定した。
コークス供給速度(kg/h)
=(%CO+%CO2)/100×Q/22.4×12/(コークス中の炭素割合)
(「%CO」及び「%CO2」は、それぞれ、排ガス中のCO濃度およびCO2濃度(体積%)を表す。)
After charging the slag, oxygen was supplied from the top blowing lance, and the melt reforming reduction treatment was performed for 18 minutes. The treatment temperature was 1400 ° C. to 1470 ° C., and the slag during the treatment was always kept in a molten state. In addition, 10-50 mm diameter coke was continuously supplied from the upper side of the reaction vessel during the melt reforming reduction treatment in order to supplement the carbon consumed by the combustion with the top blown oxygen and the reduction of the iron oxide in the slag. . Regarding the coke supply rate at this time, the amount Q (Nm 3 / h) of exhaust gas generated by the melt reforming reduction treatment and the CO concentration and CO 2 concentration (volume%) in the exhaust gas were continuously measured. Based on the value, it was determined from the following equation.
Coke supply speed (kg / h)
= (% CO +% CO 2 ) /100×Q/22.4×12/ ( carbon ratio in the coke)
(“% CO” and “% CO 2 ” represent the CO concentration and CO 2 concentration (volume%) in the exhaust gas, respectively.)
溶融改質還元処理の終了後、処理後の改質スラグをスラグ鍋に排出し、転炉型反応容器に溶銑を残存させた。ここで、スラグ排出の際、還元用炭素源として添加したコークスも同時に排出されるが、スラグの粘度が低かったことから、コークスとスラグとの分離性が良く、コークスが、スラグ中に巻き込まれることなく、スラグ層の上に浮上分離した。冷却後、転炉型反応容器内のスラグ及びコークスをスラグ鍋から取り出すと、スラグとコークスとは完全に分離でき、コークスは、次チャージの溶融改質還元処理の還元用炭素源として使用することができた。 After completion of the melt reforming reduction treatment, the treated reforming slag was discharged into a slag pan, and the hot metal remained in the converter reactor. Here, at the time of slag discharge, coke added as a reducing carbon source is also discharged at the same time, but because the viscosity of the slag was low, the separability between the coke and slag is good, and the coke is caught in the slag. Without floating on the slag layer. After cooling, when the slag and coke in the converter reactor are removed from the slag pan, the slag and coke can be completely separated, and the coke should be used as a carbon source for reduction in the melt reforming reduction treatment of the next charge. I was able to.
改質還元処理前および処理後のスラグ、本実施例で使用した石炭灰、アルミナ系耐火物屑およびコークスの成分を下記表5〜8にそれぞれ示す。なお、本実施例および以下に説明する比較例1〜2におけるスラグ組成の分析方法としては、蛍光X線分析(JIS K 0119)を、f・CaO分析にはエチレングリコール抽出法ICP発光分光分析を用いた。ただし、f・CaOの分析において、f・CaOを抽出する方法としてTBP(トリブロムフェノール)法等があり、抽出が正しくできればいずれの方法を用いても良い。 The components of the slag before and after the reforming reduction treatment, the coal ash used in this example, the alumina refractory waste, and the coke are shown in Tables 5 to 8 below. In addition, as an analysis method of a slag composition in a present Example and Comparative Examples 1-2 demonstrated below, a fluorescent X ray analysis (JISK0119) is used for f * CaO analysis, and the ethylene glycol extraction method ICP emission spectroscopic analysis is used. Using. However, in the analysis of f · CaO, there is a TBP (tribromophenol) method or the like as a method for extracting f · CaO, and any method may be used as long as the extraction can be performed correctly.
なお、下記表5におけるT.Feとは、FeOと、Fe2O3と、金属鉄の合計濃度である。FeOと、Fe2O3と、金属鉄とは、化学分析を用いれば、それぞれの濃度を独立して評価することができるが、本実施例のように、蛍光X線分析を用いた場合には、Feを含む全ての成分の合計濃度としてしか分析することができない。また、下記表5では、f・CaOは、蛍光X線分析では分析できず、上述したように別途分析した値であるため、f.CaO量は外数として示してある。 In addition, T. Fe is the total concentration of FeO, Fe 2 O 3 and metallic iron. FeO, Fe 2 O 3 and metallic iron can be evaluated independently using chemical analysis, but when fluorescent X-ray analysis is used as in this example, Can only be analyzed as the total concentration of all components including Fe. In Table 5 below, f · CaO cannot be analyzed by fluorescent X-ray analysis, but is a value analyzed separately as described above. The amount of CaO is shown as an external number.
上記表5に示すように、溶融改質還元処理後の改質スラグは、体積膨張の原因となるf・CaOが1質量%未満に低減されており、上層路盤材等の高級用途に利材化しても問題ない水準まで改質された。また、溶融改質還元処理後の改質スラグ中のT.Feは0.5質量%未満まで低減された結果、冷却後のスラグは白色化され、普通ポルトランドセメント及び白色セメントに混合しても外観上、その違いは認められなかった。 As shown in Table 5 above, the reformed slag after the melt reforming reduction treatment has f · CaO that causes volume expansion reduced to less than 1% by mass, which is useful for high-grade applications such as upper roadbed materials. It was improved to a level where there was no problem even if it was changed. In addition, the T.V. in the reformed slag after the melt reforming reduction treatment. As a result of Fe being reduced to less than 0.5% by mass, the slag after cooling was whitened, and even when mixed with ordinary Portland cement and white cement, no difference in appearance was observed.
また、得られた溶融改質還元処理後の改質スラグには、コークスが残留していなかったため、吸水率は0.6質量%と低く、圧縮強度は62N/mm2と高く、砂、骨材、割栗石等として十分使用可能な品質であった。なお、本実施例および以下に説明する比較例1〜2において、吸水率は、JIS A 1109及びJIS A 1135に準拠して測定し、圧縮強度は、JIS A 1132に準拠して測定した。 Moreover, since coke did not remain in the obtained modified slag after the melt reforming reduction treatment, the water absorption was as low as 0.6% by mass, the compressive strength was as high as 62 N / mm 2 , sand, bone It was of a quality that could be used as a wood, cracked stone, etc. In addition, in a present Example and Comparative Examples 1-2 demonstrated below, the water absorption was measured based on JISA1109 and JISA1135, and the compressive strength was measured based on JISA1132.
さらに、溶融改質還元処理後の改質スラグ中の硫黄濃度は0.1質量%と低くできたため、黄水の発生はなく、高炉スラグの代替品として使用した場合、エージング処理が不要であった。 Furthermore, since the sulfur concentration in the reformed slag after the melt reforming reduction process was as low as 0.1% by mass, yellow water was not generated, and aging treatment was not necessary when used as a substitute for blast furnace slag. It was.
また、溶融改質還元処理後の改質スラグにおいては、MnOやP2O5のような有価成分の酸化物も還元されてスラグ中の濃度が低減し、種湯溶銑に有価成分(マンガン、リン)として回収された。その結果、下記表9に示すように、種湯溶銑中のマンガンやリンの濃度は上昇した。 Further, in the reformed slag after the melt reforming reduction treatment, oxides of valuable components such as MnO and P 2 O 5 are also reduced to reduce the concentration in the slag, and the valuable components (manganese, Recovered as phosphorus). As a result, as shown in Table 9 below, the concentrations of manganese and phosphorus in the seed bath hot metal increased.
さらに、同一の種湯溶銑を用いて、溶融改質還元処理を4回繰り返して行い、有価成分(Mn,P)を回収した結果、種湯溶銑中のMn及びPの濃度を下記表10に示す濃度まで高めることができた。この後、脱リンを行い、脱リンスラグ中にP2O5として高濃度のリン成分を効率的に回収できた。 Furthermore, using the same seed hot metal, the melt reforming reduction process was repeated four times, and the valuable components (Mn, P) were recovered. As a result, the concentrations of Mn and P in the seed hot metal are shown in Table 10 below. The concentration shown can be increased. Thereafter, dephosphorization was performed, and a high concentration phosphorus component was efficiently recovered as P 2 O 5 in the dephosphorization slag.
(比較例1)
種湯溶銑100tを保持する転炉型反応容器に、SiO2含有改質材として使用する5〜10mm径の石炭灰2t、Al2O3含有物質として使用する5〜20mm径に粉砕したアルミナ系耐火物屑5.1t、還元用炭素源として使用する10〜50mm径のコークス3.3tを事前に一括投入した。その後、溶銑予備処理スラグ20tを溶融状態のまま転炉型反応容器に装入した。なお、石炭灰の投入量およびアルミナ系耐火物屑の投入量は、転炉型反応容器に装入する前の溶銑予備処理スラグを採取し、蛍光X線分析装置にて組成を分析し、目標とするCaO/SiO2の比1.2およびAl2O3濃度25質量%とするのに必要なSiO2量およびAl2O3量を算出することにより決定した。また、コークスは炭素分で転炉型反応容器に装入した溶銑予備処理スラグの質量100質量%に対して外数で15質量%となる添加量とした。
(Comparative Example 1)
A converter-type reaction vessel for holding a Taneyu molten iron 100 t, alumina ground to 5~20mm diameter using coal ash 2t of 5~10mm diameter to be used as the SiO 2 content modifier, as Al 2 O 3 containing materials 5.1t of refractory waste and 3.3t of coke having a diameter of 10 to 50mm used as a carbon source for reduction were charged in advance. Thereafter, the hot metal pretreatment slag 20t was charged into the converter reactor in a molten state. The amount of coal ash and the amount of alumina refractory debris that were collected were collected from the hot metal pretreatment slag before being charged into the converter reactor, analyzed for the composition with a fluorescent X-ray analyzer, The ratio was determined by calculating the amount of SiO 2 and the amount of Al 2 O 3 required to obtain a CaO / SiO 2 ratio of 1.2 and an Al 2 O 3 concentration of 25% by mass. The coke was added in an amount of 15% by mass based on the mass of 100% by mass of the hot metal pretreatment slag charged in the converter reactor with carbon.
スラグの装入後、上吹きランスより酸素を供給し、溶融改質還元処理を18分間行った。処理温度は1400℃〜1470℃で行い、処理中のスラグを常に溶融状態に維持した。なお、上吹き酸素による燃焼やスラグ中の酸化鉄分等の還元によって消費される炭素分を補うために、溶融改質還元処理中に、反応容器の上方から10〜50mm径のコークスを連続供給した。このときのコークスの供給速度については、実施例1と同様の方法により決定した。 After charging the slag, oxygen was supplied from the top blowing lance, and the melt reforming reduction treatment was performed for 18 minutes. The treatment temperature was 1400 ° C. to 1470 ° C., and the slag during the treatment was always kept in a molten state. In addition, 10-50 mm diameter coke was continuously supplied from the upper side of the reaction vessel during the melt reforming reduction treatment in order to supplement the carbon consumed by the combustion with the top blown oxygen and the reduction of the iron oxide in the slag. . The coke supply rate at this time was determined by the same method as in Example 1.
溶融改質還元処理の終了後、処理後の改質スラグをスラグ鍋に排出し、転炉型反応容器に溶銑を残存させた。ここで、スラグ排出の際、還元用炭素源として添加したコークスも同時に排出されるが、処理後の改質スラグ中のAl2O3濃度が25質量%と高かったため、スラグの粘度が高くなり、その結果、コークスとスラグとの分離性が悪かった。そのため、冷却後の改質スラグの内部には浮上分離できなかったコークス粒が多数存在した状態であった。 After completion of the melt reforming reduction treatment, the treated reforming slag was discharged into a slag pan, and the hot metal remained in the converter reactor. Here, at the time of slag discharge, coke added as a carbon source for reduction is also discharged at the same time. However, since the Al 2 O 3 concentration in the modified slag after treatment was as high as 25% by mass, the viscosity of the slag increased. As a result, the separability between coke and slag was poor. Therefore, a large number of coke grains that could not be floated and separated were present inside the modified slag after cooling.
改質還元処理前および処理後のスラグの成分を下記表11に示す。また、本比較例では、石炭灰、アルミナ系耐火物屑およびコークスについては、上記実施例と同様に、上記表6〜8に示した組成のものを使用した。 The slag components before and after the reforming reduction treatment are shown in Table 11 below. Moreover, in this comparative example, the thing shown in the said Tables 6-8 was used similarly to the said Example about coal ash, an alumina-type refractory waste, and coke.
なお、下記表11におけるT.Feとは、FeOと、Fe2O3と、金属鉄の合計濃度である。FeOと、Fe2O3と、金属鉄とは、化学分析を用いれば、それぞれの濃度を独立して評価することができるが、本実施例のように、蛍光X線分析を用いた場合には、Feを含む全ての成分の合計濃度としてしか分析することができない。また、下記表11では、f・CaOは、蛍光X線分析では分析できず、上述したように別途分析した値であるため、f.CaO量は外数として示してある。 In addition, T. Fe is the total concentration of FeO, Fe 2 O 3 and metallic iron. FeO, Fe 2 O 3 and metallic iron can be evaluated independently using chemical analysis, but when fluorescent X-ray analysis is used as in this example, Can only be analyzed as the total concentration of all components including Fe. In Table 11 below, f · CaO cannot be analyzed by fluorescent X-ray analysis, but is a value analyzed separately as described above. The amount of CaO is shown as an external number.
上記表11に示すように、溶融改質還元処理後の改質スラグは、体積膨張の原因となるf・CaOが1質量%未満に低減されており、上層路盤材等の高級用途に利材化しても問題ない水準まで改質された。しかし、溶融改質還元処理後の改質スラグ中のT.Feは2.5質量%と高く、スラグは白色化されず、普通ポルトランドセメント及び白色セメント用原料には使用できなかった。 As shown in Table 11 above, the modified slag after the melt reforming reduction treatment has f · CaO that causes volume expansion reduced to less than 1% by mass, and is useful for high-grade applications such as upper roadbed materials. It was improved to a level where there was no problem even if it was changed. However, the T.V. in the reformed slag after the melt reforming reduction treatment. Fe was as high as 2.5% by mass, the slag was not whitened, and could not be used for ordinary Portland cement and white cement raw materials.
また、得られた溶融改質還元処理後の改質スラグには、コークスが多量に残留していたため、吸水率は5.2質量%と高く、また、圧縮強度は5N/mm2と低く、コンクリート骨材やアスコン骨材としては使用できなかった。 Moreover, in the obtained modified slag after the melt reforming reduction treatment, a large amount of coke remained, so that the water absorption was as high as 5.2% by mass, and the compressive strength was as low as 5 N / mm 2 . It could not be used as concrete aggregate or ascon aggregate.
また、溶融改質還元処理後の改質スラグにおいて、MnOやP2O5のような有価成分の酸化物はほとんど還元されず、下記表12に示すように種湯溶銑に有価成分(マンガン、リン)として十分に回収することができなかった。 Further, in the reformed slag after the melt reforming reduction treatment, oxides of valuable components such as MnO and P 2 O 5 are hardly reduced, and valuable components (manganese, It was not possible to sufficiently recover it as phosphorus).
(比較例2)
種湯溶銑100tを保持する転炉型反応容器に、SiO2含有改質材として使用する5〜10mm径の石炭灰2t、Al2O3含有物質として使用する5〜20mm径に粉砕したアルミナ系耐火物屑0.3t、還元用炭素源として使用する10〜50mm径のコークス3.3tを事前に一括投入した。その後、溶銑予備処理スラグ20tを溶融状態のまま転炉型反応容器に装入した。なお、石炭灰の投入量およびアルミナ系耐火物屑の投入量は、転炉型反応容器に装入する前の溶銑予備処理スラグを採取し、蛍光X線分析装置にて組成を分析し、目標とするCaO/SiO2の比1.2およびAl2O3濃度6質量%とするのに必要なSiO2量およびAl2O3量を算出することにより決定した。また、コークスは炭素分で転炉型反応容器に装入した溶銑予備処理スラグの質量100質量%に対して外数で15質量%となる添加量とした。
(Comparative Example 2)
A converter-type reaction vessel for holding a Taneyu molten iron 100 t, alumina ground to 5~20mm diameter using coal ash 2t of 5~10mm diameter to be used as the SiO 2 content modifier, as Al 2 O 3 containing materials Refractory waste 0.3 t, and 10 to 50 mm diameter coke 3.3 t used as a carbon source for reduction were collectively charged in advance. Thereafter, the hot metal pretreatment slag 20t was charged into the converter reactor in a molten state. The amount of coal ash and the amount of alumina refractory debris that were collected were collected from the hot metal pretreatment slag before being charged into the converter reactor, analyzed for the composition with a fluorescent X-ray analyzer, The ratio was determined by calculating the amount of SiO 2 and the amount of Al 2 O 3 required to obtain a CaO / SiO 2 ratio of 1.2 and an Al 2 O 3 concentration of 6% by mass. The coke was added in an amount of 15% by mass based on the mass of 100% by mass of the hot metal pretreatment slag charged in the converter reactor with carbon.
スラグの装入後、上吹きランスより酸素を供給し、溶融改質還元処理を18分間行った。処理温度は1400℃〜1470℃で行い、処理中のスラグを常に溶融状態に維持した。なお、上吹き酸素による燃焼やスラグ中の酸化鉄分等の還元によって消費される炭素分を補うために、溶融改質還元処理中に、反応容器の上方から10〜50mm径のコークスを連続供給した。このときのコークスの供給速度については、実施例1と同様の方法により決定した。 After charging the slag, oxygen was supplied from the top blowing lance, and the melt reforming reduction treatment was performed for 18 minutes. The treatment temperature was 1400 ° C. to 1470 ° C., and the slag during the treatment was always kept in a molten state. In addition, 10-50 mm diameter coke was continuously supplied from the upper side of the reaction vessel during the melt reforming reduction treatment in order to supplement the carbon consumed by the combustion with the top blown oxygen and the reduction of the iron oxide in the slag. . The coke supply rate at this time was determined by the same method as in Example 1.
溶融改質還元処理の終了後、処理後の改質スラグをスラグ鍋に排出し、転炉型反応容器に溶銑を残存させた。ここで、スラグ排出の際、還元用炭素源として添加したコークスも同時に排出されるが、処理後の改質スラグ中のAl2O3濃度が6質量%と低かったため、スラグの粘度が高くなり、その結果、コークスとスラグとの分離性が悪かった。そのため、冷却後の改質スラグの内部には浮上分離できなかったコークス粒が存在した状態であった。 After completion of the melt reforming reduction treatment, the treated reforming slag was discharged into a slag pan, and the hot metal remained in the converter reactor. Here, at the time of slag discharge, coke added as a carbon source for reduction is also discharged at the same time, but since the Al 2 O 3 concentration in the modified slag after treatment was low at 6% by mass, the viscosity of the slag increased. As a result, the separability between coke and slag was poor. Therefore, coke grains that could not be floated and separated were present inside the modified slag after cooling.
改質還元処理前および処理後のスラグの成分を下記表13に示す。また、本比較例では、石炭灰、アルミナ系耐火物屑およびコークスについては、上記実施例と同様に、上記表6〜8に示した組成のものを使用した。 The slag components before and after the reforming reduction treatment are shown in Table 13 below. Moreover, in this comparative example, the thing shown in the said Tables 6-8 was used similarly to the said Example about coal ash, an alumina-type refractory waste, and coke.
なお、下記表13におけるT.Feとは、FeOと、Fe2O3と、金属鉄の合計濃度である。FeOと、Fe2O3と、金属鉄とは、化学分析を用いれば、それぞれの濃度を独立して評価することができるが、本実施例のように、蛍光X線分析を用いた場合には、Feを含む全ての成分の合計濃度としてしか分析することができない。また、下記表13では、f・CaOは、蛍光X線分析では分析できず、上述したように別途分析した値であるため、f.CaO量は外数として示してある。 In addition, T. Fe is the total concentration of FeO, Fe 2 O 3 and metallic iron. FeO, Fe 2 O 3 and metallic iron can be evaluated independently using chemical analysis, but when fluorescent X-ray analysis is used as in this example, Can only be analyzed as the total concentration of all components including Fe. In Table 13 below, f · CaO cannot be analyzed by fluorescent X-ray analysis, but is a value separately analyzed as described above. The amount of CaO is shown as an external number.
上記表13に示すように、溶融改質還元処理後の改質スラグは、体積膨張の原因となるf・CaOが1質量%未満に低減されており、上層路盤材等の高級用途に利材化しても問題ない水準まで改質された。しかし、溶融改質還元処理後の改質スラグ中のT.Feは3.1質量%と高く、スラグは黒色のままで、普通ポルトランドセメント及び白色セメント用原料には使用できなかった。 As shown in Table 13 above, the reformed slag after the melt reforming reduction treatment has f · CaO that causes volume expansion reduced to less than 1% by mass, and is useful for high-grade applications such as upper-layer roadbed materials. It was improved to a level where there was no problem even if it was changed. However, the T.V. in the reformed slag after the melt reforming reduction treatment. Fe was as high as 3.1% by mass and the slag remained black and could not be used as a raw material for ordinary Portland cement and white cement.
また、得られた溶融改質還元処理後の改質スラグには、コークスが残留していたため、吸水率は3.9質量%と高く、また、圧縮強度は6N/mm2と低く、コンクリート骨材やアスコン骨材としては使用できなかった。 Further, since coke remained in the resulting modified slag after the melt reforming reduction treatment, the water absorption was as high as 3.9% by mass, the compressive strength was as low as 6 N / mm 2, and the concrete bone It could not be used as wood or ascon aggregate.
また、溶融改質還元処理後の改質スラグにおいて、MnOやP2O5のような有価成分の酸化物はほとんど還元されず、下記表14に示すように種湯溶銑に有価成分(マンガン、リン)として十分に回収することができなかった。 Further, in the modified slag after the melt reforming reduction treatment, oxides of valuable components such as MnO and P 2 O 5 are hardly reduced, and as shown in Table 14 below, valuable components (manganese, It was not possible to sufficiently recover it as phosphorus).
以上、添付図面を参照しながら本発明の好適な実施形態について説明したが、本発明はかかる例に限定されないことは言うまでもない。当業者であれば、特許請求の範囲に記載された範疇内において、各種の変更例または修正例に想到し得ることは明らかであり、それらについても当然に本発明の技術的範囲に属するものと了解される。
As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.
Claims (2)
前記改質スラグ中のAl2O3濃度が7質量%以上20質量%以下であり、
前記改質スラグの塩基度が0.7以上であり、
前記改質スラグ中のS濃度が0.7質量%以下であり、
前記改質スラグ中のトータル鉄の濃度が1質量%以下であることを特徴とする、改質スラグ。 While the steelmaking slag charged in the reaction vessel holding the hot metal is heated by a heating means using oxygen gas, the SiO 2 -containing modifier and the reducing carbon source are added to the steelmaking slag, and the steelmaking A modified slag obtained by subjecting a slag to a melt reforming reduction treatment,
Al 2 O 3 concentration in the modified slag is 7% by mass or more and 20% by mass or less,
The basicity of the modified slag is 0.7 or more,
The S concentration in the reformed slag Ri der than 0.7 wt%,
The modified slag is characterized in that the total iron concentration in the modified slag is 1% by mass or less .
The modified slag according to claim 1 , wherein the MgO concentration in the modified slag is 15 mass% or less.
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