JP6720937B2 - Steelmaking slag roadbed material manufacturing method - Google Patents
Steelmaking slag roadbed material manufacturing method Download PDFInfo
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- JP6720937B2 JP6720937B2 JP2017150871A JP2017150871A JP6720937B2 JP 6720937 B2 JP6720937 B2 JP 6720937B2 JP 2017150871 A JP2017150871 A JP 2017150871A JP 2017150871 A JP2017150871 A JP 2017150871A JP 6720937 B2 JP6720937 B2 JP 6720937B2
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- 239000002893 slag Substances 0.000 title claims description 269
- 238000009628 steelmaking Methods 0.000 title claims description 150
- 239000000463 material Substances 0.000 title claims description 40
- 238000004519 manufacturing process Methods 0.000 title claims description 25
- 239000002245 particle Substances 0.000 claims description 149
- 230000032683 aging Effects 0.000 claims description 70
- 238000009826 distribution Methods 0.000 claims description 60
- 239000010419 fine particle Substances 0.000 claims description 45
- 239000000843 powder Substances 0.000 claims description 34
- 238000000034 method Methods 0.000 claims description 23
- 238000007670 refining Methods 0.000 claims description 9
- 230000003247 decreasing effect Effects 0.000 claims description 7
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 5
- 239000008187 granular material Substances 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 43
- 238000007654 immersion Methods 0.000 description 34
- 238000012360 testing method Methods 0.000 description 16
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 10
- 229910000831 Steel Inorganic materials 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 10
- 239000011362 coarse particle Substances 0.000 description 10
- 239000010959 steel Substances 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 8
- 238000012856 packing Methods 0.000 description 8
- 239000000395 magnesium oxide Substances 0.000 description 5
- 238000005056 compaction Methods 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 229920006395 saturated elastomer Polymers 0.000 description 4
- 230000007704 transition Effects 0.000 description 4
- 238000005261 decarburization Methods 0.000 description 3
- 230000006641 stabilisation Effects 0.000 description 3
- 238000011105 stabilization Methods 0.000 description 3
- 238000006703 hydration reaction Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000004575 stone Substances 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- BCAARMUWIRURQS-UHFFFAOYSA-N dicalcium;oxocalcium;silicate Chemical compound [Ca+2].[Ca+2].[Ca]=O.[O-][Si]([O-])([O-])[O-] BCAARMUWIRURQS-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 235000019976 tricalcium silicate Nutrition 0.000 description 1
- 229910021534 tricalcium silicate Inorganic materials 0.000 description 1
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- Processing Of Solid Wastes (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
- Treatment Of Steel In Its Molten State (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
Description
この発明は、製鋼スラグを加圧蒸気エージングして製造される製鋼スラグ路盤材の製造方法に関する。 The present invention relates to a method for producing a steelmaking slag roadbed material produced by pressurizing steam aging a steelmaking slag.
製鋼スラグは、精練で添加される石灰源やマグネシア源の一部が未溶融或いは他の成分と化合物を形成しないで遊離したまま残留している。このような遊離ＣａＯや遊離ＭｇＯが水分と水和反応すると、体積が２倍以上に膨張して周囲の構造物を破壊するため、製鋼スラグを石材や道路路盤材として利用するには、使用前の段階で水和反応を促進して沈静化しておく必要がある。 In the steelmaking slag, a part of the lime source or magnesia source added in the refining remains unmelted or remains free without forming a compound with other components. When such free CaO or free MgO undergoes a hydration reaction with water, the volume expands more than twice and destroys the surrounding structures. Therefore, before using steelmaking slag as a stone material or a roadbed material, It is necessary to promote the hydration reaction and calm it at the stage.
製鋼スラグ中の遊離ＣａＯや遊離ＭｇＯを水分と速やかに反応させるのに、昇温と水分供給を同時に行なう蒸気での反応促進（蒸気エージング）が一般的に実施されている。そのなかでも、高温高圧の蒸気を用いる加圧蒸気エージングは高速での処理が可能である。従来、この加圧蒸気エージングを実施するための装置やエージングパターンについての提案がいくつかなされている。 In order to rapidly react free CaO and free MgO in the steelmaking slag with water, reaction acceleration (steam aging) with steam that simultaneously raises temperature and supplies water is generally performed. Among them, the pressurized steam aging using high-temperature and high-pressure steam can be processed at high speed. Heretofore, some proposals have been made regarding an apparatus and an aging pattern for carrying out this pressurized steam aging.
特許文献１には、加圧蒸気エージング時の温度−圧力の推移パターンが示されており、加圧保持時の途中で蒸気圧を短時間下げ、再度高圧に昇圧して処理する方法が示されている。
また、特許文献２には、細粒で蒸気の進入が容易でないスラグでも加圧蒸気エージングを短時間で行うために、スラグ収納容器の内部に蒸気配管を通して、スラグ充填部の内部から蒸気を吹き込む方法が示されている。
In addition, in
製鋼スラグを蒸気エージングするとスラグ粒子の一部は膨張反応で崩壊するため、粒度分布は細かい側に変化する。膨張を抑制しようとして、加圧蒸気エージングの時間を長くしたり、温度や圧力を高めたりすると、細粒化は進むが膨張性の安定化は鈍る。そうして、路盤材製品の膨張基準を満たすような安定した路盤材を製造するエージング処理の生産性が落ちる。 When steam aging the steelmaking slag, some of the slag particles collapse due to expansion reaction, so the particle size distribution changes to the finer side. If the time for pressurized steam aging is increased or the temperature or pressure is increased in an attempt to suppress expansion, grain refinement proceeds but expansion stability is slowed. As a result, the productivity of the aging treatment for producing a stable roadbed material that satisfies the expansion standard of the roadbed material product is reduced.
特許文献１の方法は、加圧蒸気エージング中の圧力変化により粒子の崩壊を進めて安定化を図るものであるが、塩基度が高く、遊離ＣａＯ含有量が多いものは膨張崩壊を繰り返して粒子の新しい膨張源を露出させ続けるため、安定化するのに非効率に細粒化が進みすぎる問題がある。また、特許文献２の方法は、細かい粒子にも蒸気は進入して昇温されるが、より細粒化させる傾向が強くなる。
The method of
したがって本発明の目的は、製鋼スラグを加圧蒸気エージングして製鋼スラグ路盤材を製造する方法において、膨張性が極めて低い製鋼スラグ路盤材を高い生産性で製造することができる製造方法を提供することにある。 Therefore, an object of the present invention is to provide a production method capable of producing a steelmaking slag roadbed material having extremely low expandability with high productivity in a method of producing a steelmaking slag roadbed material by pressurizing steam aging a steelmaking slag. Especially.
上記課題を解決するための本発明の要旨は以下のとおりである。
［1］粒径４０ｍｍ以下の割合が８０mass％以上となる粒度に破砕した後に加圧蒸気エージングを施した製鋼スラグ（ａ）について、下記（ｉ）又は（ii）の条件で細粒・微粉分を増減することにより、製鋼スラグ（ａ）の粒度分布をAndreazenの曲線式で近似した場合に、Fuller指数が０．４〜０．６となるように製鋼スラグ（ａ）の粒度分布を調整することを特徴とする製鋼スラグ路盤材の製造方法。
（ｉ）製鋼スラグ（ａ）の一部について篩目が１０ｍｍ以下の篩（ｘ）で分級することで細粒・微粉分を減じた後、製鋼スラグ（ａ）の残部と混合する。
（ii）以前に、粒径４０ｍｍ以下の割合が８０mass％以上となる粒度に破砕され且つ該破砕後に加圧蒸気エージングが施された製鋼スラグを篩目が１０ｍｍ以下の篩（ｘ）で分級することで得られている細粒・微粉分を、製鋼スラグ（ａ）に加えて混合する。
The gist of the present invention for solving the above problems is as follows.
[1] Steelmaking slag (a) that has been subjected to pressure steam aging after crushing to a particle size with a particle size of 40 mm or less of 80 mass% or more, fine particle and fine powder content under the following conditions (i) or (ii) By adjusting, the particle size distribution of the steelmaking slag (a) is adjusted so that the Fuller index becomes 0.4 to 0.6 when the particle size distribution of the steelmaking slag (a) is approximated by the Andreazen curve formula. A method for manufacturing a steelmaking slag roadbed material, which is characterized in that
(I) A part of the steelmaking slag (a) is classified with a sieve (x) having a mesh size of 10 mm or less to reduce fine particles and fine powders, and then mixed with the rest of the steelmaking slag (a).
(Ii) Classifying the steelmaking slag previously crushed to a particle size having a particle size of 40 mm or less to 80 mass% or more and subjected to pressurized steam aging after the crushing with a sieve (x) having a mesh size of 10 mm or less. The fine granules/fine powders thus obtained are added to the steelmaking slag (a) and mixed.
［2］上記［1］の製造方法において、製鋼スラグ（ａ）の少なくとも一部が、塩基度（但し、ＣａＯ／ＳｉＯ２の質量比）が３．３以上の製鋼スラグであることを特徴とする製鋼スラグ路盤材の製造方法。
［3］上記［1］又は［2］の製造方法において、製鋼スラグ（ａ）が同日に同じ精錬設備で発生した脱炭スラグであり、該製鋼スラグ（ａ）の一部について篩目が１０ｍｍ以下の篩（ｘ）で分級することで細粒・微粉分を減じた後、製鋼スラグ（ａ）の残部と混合することにより、製鋼スラグ（ａ）の細粒・微粉分を減少させて粒度分布を調整することを特徴とする製鋼スラグ路盤材の製造方法。
[2] In the manufacturing method of the above-mentioned [1], at least a part of the steelmaking slag (a) is a steelmaking slag having a basicity (however, a CaO/SiO 2 mass ratio) of 3.3 or more. Method for manufacturing steelmaking slag roadbed material.
[3] In the manufacturing method according to [1] or [2], the steelmaking slag (a) is decarburized slag generated in the same refining equipment on the same day, and a part of the steelmaking slag (a) has a sieve mesh of 10 mm. Fine particles and fines are reduced by classifying with the following sieve (x), and then mixed with the rest of the steelmaking slag (a) to reduce the fines and fines content of the steelmaking slag (a) to reduce the particle size. A method for producing a steelmaking slag roadbed material, which comprises adjusting the distribution.
［4］上記［1］又は［2］の製造方法において、製鋼スラグ（ａ）が２種以上の製鋼スラグからなり、そのなかの１種の製鋼スラグ（ａ1）の全部又は一部について篩目が１０ｍｍ以下の篩（ｘ）で分級することで細粒・微粉分を減じた後、残りの１種以上の製鋼スラグ（ａ2）及び製鋼スラグ（ａ1）の残部（但し、製鋼スラグ（ａ1）の全部を上記分級した場合を除く。）と混合することにより、製鋼スラグ（ａ）の細粒・微粉分を減少させて粒度分布を調整することを特徴とする製鋼スラグ路盤材の製造方法。
［5］上記［4］の製造方法において、製鋼スラグ（ａ1）が同日に同じ精錬設備で発生した脱炭スラグであり、製鋼スラグ（ａ2）が脱炭スラグ以外の製鋼スラグであることを特徴とする製鋼スラグ路盤材の製造方法。
[4] In the manufacturing method of the above-mentioned [1] or [2], the steelmaking slag (a) is composed of two or more kinds of steelmaking slag, and one or more of the steelmaking slag (a1) is sieve mesh. The fine particles and fines are reduced by classifying with a sieve (x) having a diameter of 10 mm or less, and the remaining one or more types of steelmaking slag (a2) and the rest of the steelmaking slag (a1) (however, steelmaking slag (a1) Of the steelmaking slag (a) is mixed to reduce the fine grain/fine powder content of the steelmaking slag (a) to adjust the particle size distribution.
[5] In the manufacturing method of the above-mentioned [4], the steelmaking slag (a1) is a decarburizing slag generated in the same refining equipment on the same day, and the steelmaking slag (a2) is a steelmaking slag other than the decarburizing slag. A method for manufacturing a steelmaking slag base material.
［6］上記［1］〜［5］のいずれかの製造方法において、篩（ｘ）の篩目が５ｍｍ（但し、呼び径）であることを特徴とする製鋼スラグ路盤材の製造方法。
［7］上記［1］〜［6］のいずれかの製造方法において、加圧蒸気エージングでは、蒸気圧力０．２０〜１．９６ＭＰａで１〜５時間保持することを特徴とする製鋼スラグ路盤材の製造方法。
［8］上記［1］〜［7］のいずれかの製造方法において、粒度分布を調整した後の製鋼スラグ（ａ）の粒度が、ＪＩＳ Ａ５０１５（２０１３）に粒度範囲が定められているＣＳ−４０、ＣＳ−３０、ＣＳ−２０、ＭＳ−２５、ＨＭＳ−２５のいずれかの粒度範囲を満足することを特徴とする製鋼スラグ路盤材の製造方法。
[6] The method for producing a steelmaking slag roadbed material according to any one of the above [1] to [5], wherein the sieve (x) has a mesh size of 5 mm (however, the nominal diameter).
[7] The steelmaking slag roadbed material according to any one of the above-mentioned [1] to [6], characterized in that in the pressurized steam aging, the steam pressure is maintained at a steam pressure of 0.20 to 1.96 MPa for 1 to 5 hours. Manufacturing method.
[8] In the production method according to any one of the above [1] to [7], the grain size of the steelmaking slag (a) after the grain size distribution is adjusted is CS- whose grain size range is defined in JIS A5015 (2013). 40, CS-30, CS-20, MS-25, HMS-25 satisfying the particle size range of any one, The manufacturing method of the steelmaking slag roadbed material characterized by the above-mentioned.
本発明によれば、適用したエージング条件で到達し得る最低レベルにまで膨張性を低減した製鋼スラグ路盤材を高い生産性で製造することできる。このため膨張性の製鋼スラグを従来と同じエージング条件や蒸気原単位で加圧蒸気エージングした場合でも、より多くの膨張率合格品（路盤材製品）を得ることができる。また、本発明法で製造された製鋼スラグ路盤材は、膨張性が極めて低いだけでなく、密度が高いため締め固め性にも優れている。 According to the present invention, it is possible to manufacture a steelmaking slag roadbed material having a reduced expandability to the lowest level that can be reached under the applied aging conditions with high productivity. Therefore, even when the expansive steelmaking slag is subjected to pressurized steam aging under the same aging conditions and steam basic unit as the conventional one, more expansion rate acceptable products (roadbed material products) can be obtained. Further, the steelmaking slag roadbed material manufactured by the method of the present invention not only has extremely low expandability, but also has high compactness and therefore is excellent in compaction.
本発明者は以下のような実験を行った。
路盤材の膨張性評価に用いられる突き固め試験では、条件により突き固め回数が決められている。ＪＩＳ Ａ１２１０（２００９）に定められたＥ−ｂの方法では、内径１５０ｍｍの円筒容器（ＣＢＲ試験型枠）に１層につき４．５ｋｇのランマを９２回落下させて突き、これを３層で突いて高さ１２５ｍｍに突き固める。突き固めた供試体の質量が分かれば、事前に調整した含水比を基にして、乾燥時の供試体質量および密度が求められる。
The present inventor conducted the following experiment.
In the tamping test used to evaluate the expansiveness of roadbed materials, the tamping frequency is determined depending on the conditions. According to the Eb method specified in JIS A1210 (2009), a 4.5 kg rammer is dropped 92 times into a cylindrical container (CBR test form) having an inner diameter of 150 mm, and the rammer is pierced by three layers. And squeeze it to a height of 125 mm. If the mass of the tamped specimen is known, the mass and density of the specimen when dried can be obtained based on the water content ratio adjusted in advance.
標準９２回／層×３層の突き固めを、４６回／層×３層、９２回／層×３層、１８４回／層×３層と変化させて製鋼スラグの突き固めを行い、突き固めた各供試体の乾燥密度を測定した。その結果を図１に示すが、突き固め回数を増やすと乾燥密度は増大している。一方、突き固めた供試体を８０℃に保持した水槽に浸漬して膨張の推移を計測した。図２に、この水浸試験での各供試体の膨張率の推移を示すが、膨張率は密度の小さい順に大きくなっている。すなわち、膨張率は４６回／層＞９２回／層＞１８４回／層となっている。上記３層の突き固めにおいて、１層だけ突き固めた時点の試料を採取し、粒度分布測定した結果を図３に示すが、突き固め回数が１８４回では粗粒が若干崩壊した様子が分かる。 The standard tamping of 92 times/layer×3 layers is changed to 46 times/layer×3 layers, 92 times/layer×3 layers, 184 times/layer×3 layers, and the tamping of the steelmaking slag is performed. The dry density of each sample was measured. The results are shown in Fig. 1, and the dry density increases as the number of times of tamping is increased. On the other hand, the tamped specimen was immersed in a water tank kept at 80° C. and the transition of expansion was measured. FIG. 2 shows the transition of the expansion coefficient of each test piece in this water immersion test. The expansion coefficient increases in the order of increasing density. That is, the expansion rate is 46 times/layer>92 times/layer>184 times/layer. FIG. 3 shows the result of measuring the particle size distribution by collecting a sample when only one layer was tamped in the above-mentioned three-layer tamping, and when the number of tamping is 184, it can be seen that the coarse particles have collapsed slightly.
以上の結果は、数多く突き固めて多少粒子が壊れたとしても、密度が高くなるように充填させた方が膨張は小さくなることを示している。
その他これまで、加圧蒸気エージング温度を１５８℃から１８３℃（蒸気圧力で０．５ＭＰａ〜０．９５ＭＰａ）、保持時間を２時間から１２時間まで変化させた種々の条件で試験した水浸膨張試験供試体（製鋼スラグ）について乾燥密度と水浸膨張率（ここでは８０℃一定保持で４日後の膨張率で比較）を調べた結果では、乾燥密度が小さい供試体ほど膨張性が大きい傾向があった。
The above results show that even if many particles are compacted and the particles are broken to some extent, the expansion is smaller when the particles are packed so as to have a higher density.
Others Water immersion expansion test that has been tested under various conditions such that the pressurized steam aging temperature is 158°C to 183°C (steam pressure is 0.5 MPa to 0.95 MPa) and the holding time is changed from 2 hours to 12 hours. As a result of examining the dry density and the water immersion expansion rate (here, the expansion rate after 4 days at a constant temperature of 80° C.) of the test piece (steel slag) was examined, the test piece with a smaller dry density tended to have a higher expansion property. It was
図４は１５８℃（蒸気圧力：０．５ＭＰａ、保持時間：３±１時間）で加圧蒸気エージングを施した供試体（製鋼スラグ）の乾燥密度と水浸膨張率との関係を、図５は１７３〜１８３℃（蒸気圧力：０．７５〜１．０ＭＰａ、保持時間：３±１時間）で加圧蒸気エージングを施した供試体（製鋼スラグ）の乾燥密度（ＪＩＳ Ａ１２１０（２００９）に定められたＥ−ｂの方法に従い標準９２回／層×３層の突き固めを行って得られた乾燥密度）と水浸膨張率との関係を、それぞれ示しているが、加圧蒸気エージングの温度が異なっても同様の傾向が見られる。 FIG. 4 shows the relationship between the dry density and the water immersion expansion coefficient of a test piece (steel slag) subjected to pressure steam aging at 158° C. (steam pressure: 0.5 MPa, holding time: 3±1 hour). Is the dry density (JIS A1210 (2009)) of the specimen (steel slag) that has been subjected to pressure steam aging at 173 to 183° C. (steam pressure: 0.75 to 1.0 MPa, holding time: 3±1 hour). The following shows the relationship between the water swelling rate and the dry density obtained by compacting standard 92 times/layer×3 layers according to the method of E-b. The same tendency can be seen even if is different.
一つのスラグ粒子に注目した場合、充填性が高く周囲の粒子からの拘束が大きいと、粒子の亀裂内にある膨張源が反応して膨張し、粒子自体を膨張させようとしても、拘束されて自由には反応が進まない。膨張反応によって粒子をより破壊して亀裂を進展させれば、反応進行中の膨張源や進展した亀裂先端にある未反応膨張源に水分が到達する空間が広げられる。しかし、粒子周辺の拘束が強いと、水分を膨張源に供給するための空間を容易には広げられず、結果として、膨張反応が抑制される。 When focusing on one slag particle, if the packing property is high and the constraint from the surrounding particles is large, the expansion source in the crack of the particle reacts and expands, and even if it tries to expand the particle itself, it is restricted. There is no reaction to freedom. If the particles are further destroyed by the expansion reaction to propagate the crack, the space where moisture reaches the expansion source in the progress of the reaction and the unreacted expansion source at the tip of the expanded crack is expanded. However, if the constraints around the particles are strong, the space for supplying water to the expansion source cannot be easily expanded, and as a result, the expansion reaction is suppressed.
製鋼スラグの密度を高めるには、粗粒が密に配列し、粗粒間に生じる空隙を細粒が埋め、さらに微粉が細粒間に残る空隙を埋めていくのが望ましい。しかし、空隙を埋めるのに必要以上の細粒、微粉があれば、細粒どうしが接して小さな空隙を多数生じるために、結局、最密な充填からは離れていく。加圧蒸気エージングを長くしても、細粒が必要以上に増えてしまえば、スラグ粒子のパッキングを悪化させて、膨張率の低減化を妨げる。 In order to increase the density of the steelmaking slag, it is desirable that the coarse particles are densely arranged, the fine particles fill the voids generated between the coarse particles, and further the fine powder fills the voids remaining between the fine particles. However, if there are more fine particles or fine powders than necessary to fill the voids, the fine particles come into contact with each other to form a large number of small voids, so that the final packing is separated from the closest packing. Even if the pressurized steam aging is lengthened, if the fine particles increase more than necessary, the packing of the slag particles is deteriorated and the reduction of the expansion coefficient is hindered.
加圧蒸気エージングを施した種々の製鋼スラグの粒度分布について調べたところ、粒度分布にかなりの差があることが判った。
連続粒度分布の表現についてAndreasenの曲線式があり、最大粒径（Ｄｐmax）に対して各中間径（Ｄｐ）での通過質量分率についてFuller指数ｑを用いて下記（1）式のように表す。
Ｕ（Ｄｐ）＝（Ｄｐ／Ｄｐmax）ｑ …（1）
ここで、Ｄｐは粒径、Ｄｐmaxは最大粒径、Ｕ（Ｄｐ）は粒径Ｄｐまでの通過質量分率である。（出典：例えば「三輪茂雄、粉体工学、日刊工業新聞社、1981年、p.42」）
このAndreasenの曲線は図６のような積算分布になり、細かい粒子が多いほどFuller指数ｑは小さい値となる。実験的には、疎充填ではｑ＝１／２で、密充填ではｑ＝１／３で、それぞれ最も密度が高くなるとされている。
Examination of the particle size distributions of various steelmaking slags subjected to pressurized steam aging revealed that there was a considerable difference in the particle size distributions.
There is Andreasen's curve formula for the expression of continuous particle size distribution, and it is expressed as the following formula (1) using the Fuller index q for the passing mass fraction at each intermediate diameter (Dp) with respect to the maximum particle diameter (Dpmax). ..
U(Dp)=(Dp/Dpmax) q (1)
Here, Dp is the particle size, Dpmax is the maximum particle size, and U(Dp) is the mass fraction passing through to the particle size Dp. (Source: "Shigeo Miwa, Powder Engineering, Nikkan Kogyo Shimbun, 1981, p.42")
This Andreasen curve has an integrated distribution as shown in FIG. 6, and the more fine particles there are, the smaller the Fuller index q is. Experimentally, it is said that the sparse packing has q=1/2, and the dense packing has q=1/3, and the density is highest.
最大粒径ＤｐmaxとFuller指数ｑを変数として、加圧蒸気エージングを施した種々の製鋼スラグ試料の粒度分布をAndreasenの曲線式で近似した。各試料の突き固め時の乾燥密度（ＪＩＳ Ａ１２１０（２００９）に定められたＥ−ｂの方法に従い標準９２回／層×３層の突き固めを行って得られた乾燥密度）とFuller指数ｑの関係を図７に示す。図７によれば、乾燥密度はｑが０．４〜０．６で最大となり、その前後は小さくなる傾向がある。細粒・微粉が増えるとｑは０．４を下回って、乾燥密度が小さくなる。逆にｑが０．６を上回るのは細粒・微粉を試験的に低減した水準であるが、やはり乾燥密度が小さい。これはｑに充填に最適な範囲があるということであり、Andreasenの曲線式の傾向にも合致している。 With the maximum grain size Dpmax and the Fuller index q as variables, the grain size distributions of various steelmaking slag samples subjected to pressurized steam aging were approximated by Andreasen's curve formula. The dry density of each sample at the time of compaction (dry density obtained by compacting standard 92 times/layer×3 layers according to the method of Eb defined in JIS A1210 (2009)) and the Fuller index q The relationship is shown in FIG. According to FIG. 7, the dry density has a maximum at q of 0.4 to 0.6, and tends to be small before and after that. When fine particles and fine powders increase, q becomes less than 0.4 and the dry density becomes small. On the other hand, q exceeds 0.6 at a level where fine particles and fine powder are experimentally reduced, but the dry density is also small. This means that q has an optimal range for packing, which is also in agreement with the trend of Andreasen's curve formula.
製鋼スラグの実際の破砕プラントにおいて、単純に破砕過程及び分級した粗粒の再破砕を経た製品では、細粒・微粉が例えば鉄鋼スラグ路盤材のＪＩＳ規格（ＪＩＳ Ａ５０１５）に照らして必要より少ないことはあまりなく、概ね細かく砕きすぎる場合が多いと考えられる。
さきに挙げた図７において乾燥密度が小さく、膨張が大きかった水準は殆んどｑが０．４未満である。ちなみに１５８℃（蒸気圧力０．５ＭＰａ）で加圧蒸気エージングを施した製鋼スラグの水浸膨張率（８０℃一定保持で４日後の膨張率）とFuller指数ｑとの関係をみると、図８に示すようにｑ＝０．５に向かって水浸膨張率が低下している。
In an actual crushing plant for steelmaking slag, products that have undergone a simple crushing process and re-crushing of coarse particles that have been classified should have fine particles and fine powder less than necessary in light of the JIS standard (JIS A5015) for steel slag roadbed materials, for example. It is thought that there are not many, and there are many cases where they are generally finely crushed.
In the above-mentioned FIG. 7, the dry density is small and the expansion is large at most q of less than 0.4. By the way, the relationship between the water immersion expansion coefficient (expansion coefficient after 4 days at a constant temperature of 80° C.) and the Fuller index q of the steelmaking slag subjected to pressure steam aging at 158° C. (steam pressure 0.5 MPa) is shown in FIG. As shown in, the water immersion expansion coefficient decreases toward q=0.5.
Fuller指数ｑが０．６より大きくなると、粗粒どうしが接触する頻度が高くなり、粗粒間の空隙を埋める細粒が不足して、充填性が低下する。この場合も粒子間の拘束が低くなり、膨張崩壊をより自由に進められる環境になる。さらに、粗粒ばかりの場合は、ＪＩＳ Ａ５０１５に規定された水浸膨張試験で、試料粒子を型枠の中に突き固める際に、ランマの衝撃を粗粒が直接受ける確率が増し、かつ粗粒に接触している粒子が低充填で少ないため、周囲に応力を分散できなくなって、衝撃を受けた粗粒が高頻度で崩壊する。そうすると、新しい破面に未反応の膨張源が出現するため、加圧蒸気エージングしたにも拘わらず、水浸膨張試験前に多くの未反応膨張源が反応しやすい状況となって、水浸膨張率を上昇させることになる。したがって、粒度を単純に粗粒化すればよい訳でもない。 If the Fuller index q is greater than 0.6, the coarse particles will come into contact with each other more frequently, and the fine particles that fill the voids between the coarse particles will be insufficient, resulting in a decrease in the filling property. Also in this case, the restraint between particles becomes low, and an environment in which expansion and collapse can proceed more freely is created. Furthermore, in the case of only coarse particles, the probability of the coarse particles being directly impacted by a rammer increases when the sample particles are tamped in the mold in a water immersion expansion test specified in JIS A5015, and Since the number of particles in contact with is low and small, it becomes impossible to disperse the stress in the surroundings, and the impacted coarse particles frequently collapse. Then, an unreacted expansion source will appear on the new fracture surface, and despite the pressurized steam aging, many unreacted expansion sources will easily react before the water immersion expansion test. Will increase the rate. Therefore, it is not necessary to simply coarsen the grain size.
以上のことから、本発明者は、加圧蒸気エージングを施した製鋼スラグの水浸膨張は粒度分布によっても影響を受けており、粒度分布が不適切であるためにスラグ粒子の充填性が低下すると、水浸膨張が増大していることを見出した。したがって、望まれる加圧蒸気エージングを実施しても、粒度分布が不適切であることによって膨張性が不合格判定になることが相当数起こっているものと考えられる。特に加圧蒸気エージングでは、高温で膨張反応を短時間で促進して、反応し得る膨張源を極力反応させきることを志向するので、膨張崩壊によって細粒・微粉分が増大しやすく、粒度分布が不適切になりやすい。また、塩基度が高い製鋼スラグの場合、膨張源の遊離ＣａＯがスラグ内に広範に分布しているため、どの破面にも膨張源が現れることとなり、膨張崩壊の連鎖はさらに強くなる。このような現象は、特に塩基度（但し、ＣａＯ／ＳｉＯ２の質量比。以下同様）が３．３以上の製鋼スラグで顕著になる。これは、スラグが凝結する高温段階で鉱物相中に３ＣａＯ・ＳｉＯ２（トリカルシウムシリケート）が現れるが、それが１２５０℃を下回るとＣａＯと２ＣａＯ・ＳｉＯ２に分解してフリーのＣａＯを生成するため、膨張源がスラグ組織に広範に分散してしまうためである。 From the above, the present inventor has found that the water immersion expansion of the steel slag subjected to pressurized steam aging is also affected by the particle size distribution, and the packing property of the slag particles decreases because the particle size distribution is inappropriate. Then, it was found that the water immersion expansion was increasing. Therefore, it is considered that, even if the desired pressurized steam aging is carried out, a considerable number of cases where the expansivity is judged to be rejected due to an inappropriate particle size distribution have occurred. Especially in pressurized steam aging, since we aim to accelerate the expansion reaction at high temperature in a short time and make the expansion source that can react as much as possible, fine particles and fine particles are likely to increase due to expansion collapse, and the particle size distribution Is likely to be inappropriate. Further, in the case of steelmaking slag having a high basicity, since free CaO of the expansion source is widely distributed in the slag, the expansion source appears on any fracture surface, and the chain of expansion and collapse is further strengthened. Such a phenomenon is particularly remarkable in steelmaking slag having a basicity (however, a CaO/SiO 2 mass ratio; the same applies hereinafter) of 3.3 or more. This is because 3CaO·SiO 2 (tricalcium silicate) appears in the mineral phase at a high temperature stage where slag is condensed, but when it falls below 1250°C, it decomposes into CaO and 2CaO·SiO 2 to form free CaO. Therefore, the expansion source is widely dispersed in the slag structure.
本発明者は、上記知見に基づきさらに検討を進めた結果、加圧蒸気エージングを施した製鋼スラグに対して、所定の条件で細粒・微粉分を増減することにより、適用したエージング条件で到達し得る最小の膨張率の路盤材が得られることが判った。また、特に塩基度が高い製鋼スラグの場合には、加圧蒸気エージングを施すとスラグ粒度が細粒化してしまうが、このような加圧蒸気エージング後の製鋼スラグでも、上記のように所定の条件で細粒・微粉分を増減することにより、同様に最小の膨張率の路盤材が得られることが判った。具体的には、Fuller指数ｑが０．４〜０．６となるように粒度分布を調整することが望ましいことが判った。この方法によれば、加圧蒸気エージング後の製鋼スラグの細粒・微粉分を増減するだけでよいため、膨張性が極めて低い製鋼スラグ路盤材を高い生産性で製造することができ、また、製造される製鋼スラグ路盤材は、密度が高いため締め固め性にも優れている。 The present inventor, as a result of further study based on the above findings, with respect to steelmaking slag subjected to pressurized steam aging, by increasing/decreasing the fine grain/fine powder content under a predetermined condition, the aging condition applied is reached. It was found that a roadbed material having the smallest possible expansion coefficient was obtained. Further, particularly in the case of steelmaking slag having a high basicity, the slag particle size becomes fine when subjected to pressurized steam aging, but even in the steelmaking slag after such pressurized steam aging, as described above, It was also found that the roadbed material having the minimum expansion coefficient can be obtained by increasing/decreasing the amount of fine particles and fine powder depending on the conditions. Specifically, it has been found that it is desirable to adjust the particle size distribution so that the Fuller index q is 0.4 to 0.6. According to this method, since it suffices to increase/decrease the fine particles/fine powder content of the steelmaking slag after pressurized steam aging, it is possible to manufacture a steelmaking slag roadbed material having extremely low expandability with high productivity, and The manufactured steelmaking slag roadbed material has a high density and therefore has excellent compaction properties.
このため本発明では、粒径４０ｍｍ以下の割合が８０mass％以上となる粒度に破砕した後に加圧蒸気エージングを施した製鋼スラグ（以下、説明の便宜上「製鋼スラグａ」という）について、下記（ｉ）又は（ii）の条件で細粒・微粉分を増減することにより、製鋼スラグａの粒度分布をAndreazenの曲線式で近似した場合に、Fuller指数が０．４〜０．６となるように製鋼スラグａの粒度分布を調整する。なお、粒径４０ｍｍ以下とは篩目が４０ｍｍ（呼び径）の篩を通過する粒径である。
（ｉ）製鋼スラグａの一部について篩目が１０ｍｍ以下の篩（以下、説明の便宜上「篩ｘ」という）で分級することで細粒・微粉分を減じた後、製鋼スラグａの残部（有姿粒度の製鋼スラグａ）と混合する。
（ii）以前に、粒径４０ｍｍ以下の割合が８０mass％以上となる粒度に破砕され且つ該破砕後に加圧蒸気エージングが施された製鋼スラグを篩目が１０ｍｍ以下の篩ｘで分級することで得られている細粒・微粉分を、製鋼スラグａ（有姿粒度の製鋼スラグａ）に加えて混合する。
Therefore, in the present invention, the steelmaking slag (hereinafter referred to as "steelmaking slag a" for convenience of description) crushed into particles having a particle diameter of 40 mm or less to 80 mass% or more and then subjected to pressure steam aging is described below (i. ) Or (ii) by increasing/decreasing the fine grain/fine powder content, the Fuller index becomes 0.4 to 0.6 when the grain size distribution of the steelmaking slag a is approximated by the Andreazen curve formula. The particle size distribution of the steelmaking slag a is adjusted. The particle size of 40 mm or less is a particle size that passes through a sieve having a mesh size of 40 mm (nominal diameter).
(I) A part of the steelmaking slag a is classified with a sieve having a mesh size of 10 mm or less (hereinafter, referred to as “sieve x” for convenience of description) to reduce fine particles and fine powders, and then the remaining portion of the steelmaking slag a ( Mix with steelmaking slag a) with visible grain size.
(Ii) Previously, by classifying the steelmaking slag that has been crushed to a particle size having a particle size of 40 mm or less to 80 mass% or more and subjected to pressure steam aging after the crushing with a sieve x having a mesh size of 10 mm or less. The fine particles/fine powders thus obtained are added to and mixed with the steelmaking slag a (steelmaking slag a having a physical grain size).
なお、上記（ii）の「以前に・・得られている細粒・微粉分」とは、以前に行われた分級において得られ、ストックされている細粒・微粒分のことである。
製鋼スラグは、鉄鋼製造プロセスの製鋼工程で発生するスラグであり、脱炭スラグ（転炉脱炭スラグ）、溶銑予備処理スラグ（脱珪スラグ、脱燐スラグなど）、造塊スラグ、溶融還元スラグ、電気炉スラグなどがあり、これらの１種以上を用いることができる。なかでも脱炭スラグは一般に塩基度が高いので、製鋼スラグａの一部又は全部が脱炭スラグである場合には、本発明の有用性は特に高いと言える
The “previously obtained fine grain/fine powder content” in (ii) above means the fine grain/fine particle content obtained and stocked in the classification performed previously.
Steelmaking slag is slag generated in the steelmaking process of steel manufacturing processes, and includes decarburization slag (converter decarburization slag), hot metal pretreatment slag (desiliconization slag, dephosphorization slag, etc.), ingot slag, smelting reduction slag. , Electric furnace slag, etc., and one or more of them can be used. Among them, decarburized slag generally has a high basicity, so that the utility of the present invention is particularly high when a part or all of the steelmaking slag a is decarburized slag.
本発明において、加圧蒸気エージング前の製鋼スラグａについて、その８０mass％以上を占めるスラグの最大粒径を４０ｍｍとしたのは、それより大きい径では内部に残留する膨張源が増加するため、加圧蒸気エージングを施しても水浸膨張率のバラツキが大きくなり、膨張性が安定化しないためである。
Andreazenの曲線式で積算篩下の曲線が大きく変化するのは、Fuller指数ｑが１より小さい領域では粒径が最大粒径の２０％以下の部分と考えられる。篩目４０ｍｍで８０mass％以上通過する粒度分布であれば、最大粒径の２０％の粒径は実質的に１０ｍｍとなり、それ以下の細粒・微粉分の粒子量を調整することが望ましい。このため本発明では、上記（ｉ）、（ii）のように篩目が１０ｍｍ以下の篩ｘで分級することを通じて細粒・微粉分を増減し、粒度分布を調整する。
In the present invention, regarding the steelmaking slag a before pressurized steam aging, the maximum particle size of the slag occupying 80 mass% or more thereof is set to 40 mm, because the expansion source remaining inside increases at a larger diameter, This is because even if the pressure steam aging is applied, the variation in the water immersion expansion rate becomes large and the expandability is not stabilized.
It is considered that in the area where the Fuller index q is less than 1, the particle size under the integrated sieving in the Andreazen curve formula greatly changes in the region where the particle size is 20% or less of the maximum particle size. If the particle size distribution is such that the mesh size is 40 mm and 80 mass% or more is passed, the particle size of 20% of the maximum particle size is substantially 10 mm, and it is desirable to adjust the particle amount of fine particles and fine powder below that. Therefore, in the present invention, fine particles and fine powders are increased and decreased by classifying with a sieve x having a mesh size of 10 mm or less as in the above (i) and (ii) to adjust the particle size distribution.
また、望まれるFuller指数ｑが１／２近傍で変化が大きいのは最大粒径の１０％以下（約５ｍｍ以下）の部分であり、直接的に５ｍｍ以下の粒子を増減することが粒度分布を操作しやすい。このため本発明では、上記（ｉ）、（ii）の篩ｘの篩目を５ｍｍ（呼び径）とし、その篩目を通過する粒径５ｍｍ以下の細粒・微粉分の増減を行うことが好ましい（なお、以下の説明において「粒径５ｍｍ以下」、「−５ｍｍ」とは篩目５ｍｍ（呼び径）を通過する粒径のことである。）。すなわち、上記（ｉ）のように細粒・微粉分を減じる場合には、例えば、対象となる製鋼スラグａの山（同日に同じ精錬設備で発生し、粒径４０ｍｍ以下の割合が８０mass％以上となる粒度に破砕した後に加圧蒸気エージングを施した製鋼スラグ）の一部だけ篩目が５ｍｍ（呼び径）の篩ｘで分級することで粒径５ｍｍ以下の粒子を分離し、残りの山の部分（製鋼スラグａの残部）は分級することなく有姿粒度のままとし、分級した製鋼スラグａと分級しない有姿粒度のままの製鋼スラグａを混合する。この場合、篩目が５ｍｍの篩ｘで分級する製鋼スラグａの割合を変えることで、全体での粒径５ｍｍ以下の細粒・微粉分の割合を調整できる。一方、５ｍｍ以下の粒子が不足し、上記（ii）のように不足する細粒・微粉分を増やす場合には、それ以前の分級で篩い出したストックの−５ｍｍ分（粒径４０ｍｍ以下の割合が８０mass％以上となる粒度に破砕され且つ該破砕後に加圧蒸気エージングが施された製鋼スラグを篩目が５ｍｍ（呼び径）の篩ｘで分級することで得られている細粒・微粉分）を必要なだけ加え、混合する。そして、以上のような粒度分布の調整により、Fuller指数ｑが０．４〜０．６となるようにする。
The desired change in the Fuller index q near 1/2 is large in the area of 10% or less (about 5 mm or less) of the maximum particle diameter, and directly increasing or decreasing the particles of 5 mm or less causes the particle size distribution. Easy to operate. Therefore, in the present invention, the mesh size of the screen x of (i) and (ii) is set to 5 mm (nominal diameter), and the fine particles and fine powder having a particle size of 5 mm or less passing through the mesh size can be increased or decreased. It is preferable (in the following description, “particle size of 5 mm or less” and “−5 mm” means a particle size that passes through a sieve mesh of 5 mm (nominal diameter)). That is, in the case of reducing fine particles and fine powders as in the above (i), for example, the pile of the target steelmaking slag a (generated in the same refining equipment on the same day, the proportion of
製鋼スラグ路盤材には２種以上の製鋼スラグを混合して用いることも可能である。このように製鋼スラグａが２種以上の製鋼スラグからなる場合には、そのうちの１種の製鋼スラグａ1（粒径４０ｍｍ以下の割合が８０mass％以上となる粒度に破砕した後に加圧蒸気エージングを施した製鋼スラグ）の全部又は一部について篩目が１０ｍｍ以下の篩ｘ（例えば、篩目が呼び径５ｍｍの篩ｘ）で分級することで細粒・微粉分を減じた後、分級しない有姿粒度のままの残りの１種以上の製鋼スラグａ2（粒径４０ｍｍ以下の割合が８０mass％以上となる粒度に破砕した後に加圧蒸気エージングを施した製鋼スラグ）及び製鋼スラグａ1の残部（但し、製鋼スラグａ1の全部を上記分級した場合を除く。）と混合することにより粒度分布を調整するようにしてもよい。この場合、（1）篩目が１０ｍｍ以下の篩ｘ（例えば、篩目が呼び径５ｍｍの篩ｘ）で分級する製鋼スラグａ1の割合を変えること、（2）製鋼スラグａ1と製鋼スラグａ2の量比を変えること、のいずれか又は両方により、全体での粒径５ｍｍ以下の細粒・微粉分の割合を調整できる。そして、以上のような粒度分布の調整により、Fuller指数ｑが０．４〜０．６となるようにする。
It is also possible to use a mixture of two or more types of steelmaking slag for the steelmaking slag roadbed material. Thus, when the steelmaking slag a is composed of two or more types of steelmaking slag, one of them is used to perform pressure steam aging after crushing to a particle size such that the ratio of
上記のように製鋼スラグ路盤材に２種以上の製鋼スラグを混合して用いる場合の代表例は、製鋼スラグａ1が同日に同じ精錬設備で発生した脱炭スラグであり、製鋼スラグａ2が脱炭スラグ以外の製鋼スラグである場合である。製鋼スラグａ1である脱炭スラグは一般に塩基度が高く、塩基度が３．３以上である場合が多い。一方、製鋼スラグａ2である脱炭スラグ以外の製鋼スラグは、その種類により種々の塩基度を有する。 A typical example of using two or more types of steelmaking slag mixed with steelmaking slag roadbed material as described above is steelmaking slag a1 which is decarburized slag generated in the same refining facility on the same day, and steelmaking slag a2 is decarburized. This is a case of steelmaking slag other than slag. The decarburized slag, which is the steelmaking slag a1, generally has a high basicity and often has a basicity of 3.3 or more. On the other hand, steelmaking slags other than the decarburized slag, which is the steelmaking slag a2, have various basicities depending on their types.
本発明において、Fuller指数ｑが０．４〜０．６となるように粒度分布を調整するのは、加圧蒸気エージング後の製鋼スラグａである。製鋼スラグに加圧蒸気エージングを施すとスラグが細粒化するが、塩基度が高い製鋼スラグ、特に塩基度が３．３以上の製鋼スラグは膨張源の遊離ＣａＯがスラグ内に広範に分布しているため、膨張崩壊の連鎖を生じる傾向が強く、加圧蒸気エージングを施すことにより細粒・微粉化を生じやすい。図９に、塩基度３．４~３．９の製鋼スラグを加圧蒸気エージングした場合の粒度分布の変化（加圧蒸気エージング前後での粒度分布の変化）を示す。図９に示されるように、製鋼スラグの塩基度が高いほど、加圧蒸気エージング後の細粒・微粉が増加するため、粒度分布の変化が大きくなる。また、精錬各チャージの塩基度自体のバラツキ範囲も拡大し、加圧蒸気エージング後の粒度変化が予測しにくくなる。このため、所望のFuller指数ｑに調整するには、加圧蒸気エージング後の粒度分布を測定してから粒度調整を行うことが好ましく、これによりFuller指数ｑを０．４〜０．６の範囲に確実に入れることができる。
また、上記の点からして、本発明法は、製鋼スラグａの一部又は全部が塩基度３．３以上の製鋼スラグである場合に、特に有用性が高いと言える。
In the present invention, it is the steelmaking slag a after pressurized steam aging that adjusts the particle size distribution so that the Fuller index q is 0.4 to 0.6. Although slag becomes finer when pressurized steam aging is applied to steelmaking slag, steelmaking slag with a high basicity, especially steelmaking slag with a basicity of 3.3 or more, has free CaO as an expansion source widely distributed in the slag. Therefore, there is a strong tendency to generate a chain of expansion and collapse, and fine particles and fine particles are easily generated by applying pressurized steam aging. FIG. 9 shows a change in particle size distribution when the steelmaking slag having a basicity of 3.4 to 3.9 is subjected to pressure steam aging (change in particle size distribution before and after pressure steam aging). As shown in FIG. 9, the higher the basicity of the steelmaking slag, the more the fine particles and fine powder after the pressurized steam aging increase, and the larger the change in particle size distribution. In addition, the range of variation in the basicity itself of each refining charge is expanded, and it becomes difficult to predict the change in particle size after pressurized steam aging. Therefore, in order to adjust to the desired Fuller index q, it is preferable to measure the particle size distribution after pressure steam aging and then to adjust the particle size, whereby the Fuller index q is in the range of 0.4 to 0.6. It can be put in securely.
From the above-mentioned point, it can be said that the method of the present invention is particularly useful when a part or all of the steelmaking slag a is a steelmaking slag having a basicity of 3.3 or more.
加圧蒸気エージングの圧力は製鋼スラグ中の遊離ＣａＯや遊離ＭｇＯの量に応じて調整することができる。量が多いほど、反応しうる状態にある遊離ＣａＯや遊離ＭｇＯを迅速に反応させる必要があり、温度を高くし飽和蒸気圧を上昇させた方が有利である。飽和蒸気圧を１．９６ＭＰａを超えるレベルにすると、蒸気供給設備や圧力容器が処理量に較べて大規模になり、不経済である。一方、飽和蒸気圧が０．２０ＭＰａ未満では飽和蒸気圧温度が低くなり、大気圧下で平衡する１００℃の蒸気に対しての反応促進効果が小さくなる。このため、蒸気圧は０．２０〜１．９６ＭＰａが好ましい。 The pressure of the pressurized steam aging can be adjusted according to the amounts of free CaO and free MgO in the steelmaking slag. The larger the amount, the quicker it is necessary to react free CaO and free MgO in a reactive state, and it is advantageous to raise the temperature and raise the saturated vapor pressure. When the saturated vapor pressure exceeds a level of 1.96 MPa, the steam supply equipment and the pressure vessel are large in scale as compared with the throughput, which is uneconomical. On the other hand, when the saturated vapor pressure is less than 0.20 MPa, the saturated vapor pressure temperature becomes low, and the reaction promoting effect on the vapor of 100° C. equilibrated under atmospheric pressure becomes small. Therefore, the vapor pressure is preferably 0.20 to 1.96 MPa.
加圧蒸気エージングの処理時間（保持時間）は１〜５時間程度が適当である。処理時間（保持時間）の望ましい上限を５時間としたのは、処理時間が長すぎると生産性が低下し、加圧蒸気による反応促進の優位性がなくなり、１００℃の蒸気で１０００Ｔ規模の蒸気エージングを実施するのと同程度となってしまうからである。このため、蒸気温度を上昇させて保持時間を短縮することが望ましい。また、処理時間（保持時間）の望ましい下限を１時間としたのは、圧力容器内のスラグが均一に昇温して反応促進するには、最低でも１時間は必要だからである。 The pressure steam aging treatment time (holding time) is appropriately about 1 to 5 hours. The desirable upper limit of the treatment time (holding time) is set to 5 hours, because if the treatment time is too long, the productivity is lowered, the superiority of the reaction promotion by the pressurized steam is lost, and the steam of 100° C. has a scale of 1000T. This is because the same level of aging is performed. Therefore, it is desirable to raise the steam temperature to shorten the holding time. Further, the desirable lower limit of the processing time (holding time) is set to 1 hour because at least 1 hour is required to uniformly raise the temperature of the slag in the pressure vessel and accelerate the reaction.
本発明法において、粒度分布を調整した後の製鋼スラグの粒度は、ＪＩＳ Ａ５０１５（２０１３）に粒度範囲が定められているＣＳ−４０、ＣＳ−３０、ＣＳ−２０、ＭＳ−２５、ＨＭＳ−２５のいずれかの粒度範囲を満足することが好ましい。これらは道路用鉄鋼スラグの粒度を含めた物性を規定したものであり、規格名の数字は概ねの最大粒径を示している。実用上はこの粒度を満たすものが道路舗装工事に用いられるため、路盤材用途の販売にはこの規格に合格する必要がある。
以上のような本発明法で製造される製鋼スラグ路盤材は、粒度分布をAndreazenの曲線式で近似した場合に、Fuller指数が０．４〜０．６となる粒度分布を有することが好ましい。
本発明により製造された製鋼スラグ路盤材は、単独で使用（施工）してもよいし、他の路盤材料（例えば、他のスラグ路盤材や砕石など）と混合して使用（施工）してもよい。
In the method of the present invention, the particle size of the steelmaking slag after adjusting the particle size distribution is CS-40, CS-30, CS-20, MS-25, HMS-25 whose particle size range is defined in JIS A5015 (2013). It is preferable to satisfy any of the particle size ranges of These define physical properties including the grain size of road steel slag, and the numbers in the standard names generally indicate the maximum grain size. In practice, those that meet this grain size are used in road pavement work, so it is necessary to pass this standard for the sale of roadbed materials.
The steelmaking slag roadbed material manufactured by the method of the present invention as described above preferably has a particle size distribution such that the Fuller index is 0.4 to 0.6 when the particle size distribution is approximated by the Andreazen curve formula.
The steelmaking slag roadbed material manufactured according to the present invention may be used (constructed) alone, or may be used (constructed) after being mixed with another roadbed material (for example, other slag roadbed material or crushed stone). Good.
原料となる製鋼スラグは、脱炭スラグと造塊スラグであり、いずれも粒径４０ｍｍ以下に破砕されたもの（篩目４０ｍｍ（呼び径）の篩を通過したもの）である。脱炭スラグは、遊離ＣａＯ含有量が４．９〜６．１mass％、塩基度が３．３〜４．３であり、造塊スラグは、遊離ＣａＯ含有量が１．３mass％、塩基度が２．７〜２．９であった。実施例１及び実施例２では、脱炭スラグとして、未処理状態の有姿粒度のスラグＡを加圧蒸気エージングしたスラグＢ（粒度０−４０ｍｍ）と、このスラグＢから篩目が５ｍｍ（呼び径）の篩で−５ｍｍの粒子を分級・排除したスラグＣ（粒度５−４０ｍｍ）を用いた。スラグＢとスラグＣは同日に同じ精錬設備で発生したスラグである。また、実施例２では、造塊スラグとして、分級されていない有姿粒度であって加圧蒸気エージングしたスラグＤ（粒度０−４０ｍｍ）を用いた。また、実施例３では、脱炭スラグとして、分級されていない有姿粒度であって加圧蒸気エージングしたスラグＥ（粒度０−４０ｍｍ）と、以前に、粒径４０ｍｍ以下に破砕され且つ該破砕後に加圧蒸気エージングが施された脱炭スラグを篩目が５ｍｍ（呼び径）の篩で分級した際に篩下となり、ストックされていたスラグＦ（粒度０−５ｍｍ）を用いた。なお、スラグＥは粒度０−４０ｍｍであるが、全体的に粒度が粗く、細粒分が少ない粒度分布のスラグである。
Steelmaking slag as a raw material is decarburized slag and ingot slag, both of which are crushed to have a particle size of 40 mm or less (passed through a sieve having a mesh size of 40 mm (nominal diameter)). The decarburized slag has a free CaO content of 4.9 to 6.1 mass% and a basicity of 3.3 to 4.3, and the ingot slag has a free CaO content of 1.3 mass% and a basicity. It was 2.7-2.9. In Example 1 and Example 2, as decarburizing slag, slag B (particle size 0-40 mm) obtained by pressure steam aging untreated slag A having a tangible particle size, and a mesh size of 5 mm from the slag B (nominal) Slag C (particle size 5-40 mm) obtained by classifying and eliminating particles of -5 mm with a sieve of (diameter) was used. Slag B and Slag C are slags generated on the same refining facility on the same day. Further, in Example 2, slag D (
スラグＡ〜Ｆの粒度分布を測定するとともに、スラグＡ〜ＥについてAndreasenの曲線式におけるFuller指数ｑをグラフソフトの回帰機能を用いて求めた。その一例を図１０に示す。その際、通過質量分率１００mass％、すなわち全通となる篩目の通過質量分率はデータとせず、通過質量分率１００mass％未満の篩目での通過質量分率のみをデータとして近似した。また、スラグＡ〜Ｅについて、ＪＩＳ Ａ５０１５（２０１３）附属書２に定めた水浸膨張試験を行い、乾燥密度と水浸膨張率を測定した。
スラグＢ〜Ｆのうちの２つのスラグを混合する際には、スラグの混合にホイルローダー等の重機を用い、切り返しを数度繰り返すことで混合を均一化した。
The particle size distributions of slags A to F were measured, and the Fuller index q in Andreasen's curve formula was calculated for the slags A to E by using the regression function of the graph software. An example thereof is shown in FIG. At that time, the passing mass fraction of 100 mass%, that is, the passing mass fraction of all the sieve meshes was not used as the data, and only the passing mass fraction of the sieve meshes having the passing mass fraction of less than 100 mass% was approximated as the data. Further, the slags A to E were subjected to the water immersion expansion test defined in JIS A5015 (2013)
When mixing two slags of the slags B to F, a heavy machine such as a wheel loader was used for mixing the slags, and the cutting was repeated several times to make the mixing uniform.
スラグの通過質量分率（粒度分布）を測定するのに、３７．５ｍｍ（呼び径４０ｍｍ）、３１．５ｍｍ、２６．５ｍｍ、１９．０ｍｍ、１３．０ｍｍ、９．５ｍｍ（呼び径１０ｍｍ）、４．７５ｍｍ（呼び径５ｍｍ）、２．３６ｍｍ、１．１８ｍｍ、０．６ｍｍ、０．３ｍｍ、０．１５ｍｍ、０．７５ｍｍの篩を用いた。この篩系列は、骨材粒度を測定する篩系列とスラグ路盤材の粒度を測定する篩系列の折衷となっている。これは、スラグ路盤材の篩系列よりも細粒側の分布を精密に測定するためである。ＪＩＳ Ａ５０１５（２０１３）道路用鉄鋼スラグでは水浸膨張率を１．５％以下と規定しているが、実操業では製品中のバラツキがあることを考慮して、より小さな膨張率にまで安定化することがよく行われる。本実施例では、加圧蒸気エージング後のスラグ単味で水浸膨張率を０．７％以下にまで低減することを目安とした。
加圧蒸気エージングは、蒸気吹込みにより昇温・昇圧する横置き式のオートクレーブにおいて、蒸気圧力０．９５ＭＰａで３時間保持する条件で実施した。
To measure the passing mass fraction (particle size distribution) of slag, 37.5 mm (
The pressurized steam aging was carried out in a horizontal autoclave in which the temperature was raised and the pressure was increased by blowing steam under the condition that the steam pressure was maintained at 0.95 MPa for 3 hours.
［実施例１］
比較例３を除き、−５ｍｍの細粒分を分級・排除したスラグＣ（脱炭スラグ、粒度５−４０ｍｍ）と、−５ｍｍの細粒分を分級・排除していない有姿粒度のスラグＢ（脱炭スラグ、粒度０−４０ｍｍ）を混合し、所定の粒度分布を有する発明例１〜３及び比較例１、２のスラグ（試料）とした。なお、比較例３は、有姿粒度のスラグＢ（脱炭スラグ、粒度０−４０ｍｍ）のみからなるスラグ（試料）である。各スラグについて、上述した方法で粒度分布測定とFuller指数ｑの算出を行った。また、各スラグについて、ＪＩＳ Ａ５０１５（２０１３）附属書２に定めた水浸膨張試験を行い、乾燥密度と水浸膨張率を測定した。
[Example 1]
Except for Comparative Example 3, slag C (decarburized slag, particle size 5-40 mm) in which fine particles of -5 mm were classified/excluded, and slag B having a physical particle size in which fine particles of -5 mm were not classified/excluded (Decarburized slag, particle size 0-40 mm) was mixed to obtain slags (samples) of Invention Examples 1 to 3 and Comparative Examples 1 and 2 having a predetermined particle size distribution. In addition, Comparative Example 3 is a slag (sample) composed only of slag B (decarburized slag,
それらの結果を、スラグＡ〜Ｃ単味での粒度分布、Fuller指数ｑ、水浸膨張率及び乾燥密度とともに表１及び表２に示す。これによれば、Fuller指数ｑが０．４〜０．６の範囲にある発明例１〜３は、比較例と較べて乾燥密度が高く、水浸膨張率は低い。これに対して、Fuller指数ｑが０．４よりも小さい比較例２、３と、Fuller指数ｑが０．６よりも大きい比較例１では、発明例と同じ由来のスラグであるにも関わらず乾燥密度が低く、水浸膨張率は高い。 The results are shown in Tables 1 and 2 together with the particle size distribution of slags A to C alone, Fuller index q, water immersion expansion coefficient and dry density. According to this, the invention examples 1 to 3 in which the Fuller index q is in the range of 0.4 to 0.6 have a higher dry density and a lower water immersion expansion coefficient than the comparative examples. On the other hand, in Comparative Examples 2 and 3 in which the Fuller index q is less than 0.4 and Comparative Example 1 in which the Fuller index q is greater than 0.6, the slag is derived from the same origin as the invention example. Low dry density and high water expansion coefficient.
［実施例２］
−５ｍｍの細粒分を分級・排除したスラグＣ（脱炭スラグ、粒度５−４０ｍｍ）と、−５ｍｍの細粒分を分級・排除していない有姿粒度のスラグＤ（造塊スラグ、粒度０−４０ｍｍ）を混合し、所定の粒度分布を有する発明例４及び比較例４のスラグ（試料）とした。各スラグについて、上述した方法で粒度分布測定とFuller指数ｑの算出を行った。また、各スラグについて、ＪＩＳ Ａ５０１５（２０１３）附属書２に定めた水浸膨張試験を行い、乾燥密度と水浸膨張率を測定した。
[Example 2]
Slag C (decarburized slag, particle size 5-40 mm) in which fine particles of -5 mm have been classified/excluded, and slag D in which the fine particles of -5 mm have not been classified/excluded (agglomerated slag, particle size 0-40 mm) was mixed to obtain slags (samples) of Inventive Example 4 and Comparative Example 4 having a predetermined particle size distribution. For each slag, the particle size distribution was measured and the Fuller index q was calculated by the method described above. Further, each slag was subjected to a water immersion expansion test defined in JIS A5015 (2013),
それらの結果を、スラグＣ、Ｄ単味での粒度分布、Fuller指数ｑ、水浸膨張率及び乾燥密度とともに表３及び表４に示す。これによれば、スラグＣ（脱炭スラグ、粒度５−４０ｍｍ）とスラグＤ（造塊スラグ、粒度０−４０ｍｍ）を０．７５：０．２５の割合（質量比）で混合した比較例４は、Fuller指数ｑが０．６よりも大きい。一方、スラグＣとスラグＤを０．４：０．６の割合（質量比）で混合した発明例４は、Fuller指数ｑが０．４〜０．６の範囲内にある。ここで、スラグＣ、Ｄをそれぞれ単味で使用した場合をみると、Fuller指数ｑはともに０．４〜０．６の範囲から外れているが、造塊スラグであるスラグＤは遊離ＣａＯ量が少ないために、膨張安定化が速やかに起こり、加圧蒸気エージング後の水浸膨張率は０．２８％と低い。一方、脱炭スラグであるスラグＣは、遊離ＣａＯ量がスラグＤよりも多く、乾燥密度が低く、水浸膨張率は１．６％と高い。発明例４の場合、乾燥密度が高くなり、水浸膨張率はスラグＣとスラグＤの重み付けの水浸膨張率平均より低い値となっており、粒度分布の調整による効果が現れている。 The results are shown in Tables 3 and 4 together with the particle size distributions of slags C and D alone, Fuller index q, water immersion expansion coefficient and dry density. According to this, Comparative Example 4 in which slag C (decarburized slag, particle size 5-40 mm) and slag D (agglomerated slag, particle size 0-40 mm) were mixed in a ratio (mass ratio) of 0.75:0.25. Has a Fuller index q greater than 0.6. On the other hand, in the invention example 4 in which the slag C and the slag D were mixed at a ratio (mass ratio) of 0.4:0.6, the Fuller index q was in the range of 0.4 to 0.6. Here, when the slags C and D are used individually, the Fuller index q is out of the range of 0.4 to 0.6, but the slag D that is the agglomerated slag has the free CaO amount. Since the amount is small, expansion stabilization occurs quickly, and the water immersion expansion coefficient after pressurized steam aging is as low as 0.28%. On the other hand, slag C, which is a decarburized slag, has a larger amount of free CaO than slag D, a low dry density, and a high water immersion expansion coefficient of 1.6%. In the case of Inventive Example 4, the dry density was high and the water immersion expansion coefficient was a value lower than the weighted water immersion expansion coefficient average of the slag C and the slag D, showing the effect of adjusting the particle size distribution.
[実施例３]
−５ｍｍの細粒分を分級・排除していない有姿粒度のスラグＥ（脱炭スラグ、粒度０−４０ｍｍ）と篩目５ｍｍの篩下のスラグＦ（脱炭スラグ、粒度０−５ｍｍ）を混合し、所定の粒度分布を有する発明例５のスラグ（試料）とした。このスラグについて、上述した方法で粒度分布測定とFuller指数ｑの算出を行った。また、同スラグについて、ＪＩＳ Ａ５０１５（２０１３）附属書２に定めた水浸膨張試験を行い、乾燥密度と水浸膨張率を測定した。
[Example 3]
-5 mm slag E (decarburized slag, particle size 0-40 mm), which does not classify/exclude fine particles, and slag F (decarburized slag, particle size 0-5 mm) under sieve with 5 mm mesh size are used. It mixed and it was set as the slag (sample) of the invention example 5 which has a predetermined particle size distribution. For this slag, the particle size distribution was measured and the Fuller index q was calculated by the method described above. Further, the same slag was subjected to a water immersion expansion test specified in JIS A5015 (2013),
その結果を、スラグＦ単味での粒度分布、スラグＥ単味での粒度分布、Fuller指数ｑ、水浸膨張率及び乾燥密度とともに表５及び表６に示す。これによれば、細粒分がやや少ない有姿粒度のスラグＥ（脱炭スラグ、粒度０−４０ｍｍ）はFuller指数ｑが０．６より大きい。これに対して、有姿粒度のスラグＥに細粒のスラグＦ（脱炭スラグ、粒度０−５ｍｍ）を８６：１４の割合（質量比）で混合した発明例５は、Fuller指数ｑが０．４〜０．６の範囲内にある。また、発明例５は、スラグＥに較べて乾燥密度が高く、水浸膨張率は０．７％を下回っている。 The results are shown in Tables 5 and 6 together with the particle size distribution of slag F alone, the particle size distribution of slag E alone, Fuller index q, water immersion expansion coefficient and dry density. According to this, the fuller index q of slag E (decarburized slag, particle size 0-40 mm) having a fine particle content with a slightly small amount of fine particles is larger than 0.6. On the other hand, in Invention Example 5 in which the fine-grained slag E (decarburized slag, grain size 0-5 mm) was mixed at a ratio (mass ratio) of 86:14 with the slag E having a physical grain size, the Fuller index q was 0. Within the range of 0.4 to 0.6. Inventive Example 5 has a higher dry density than Slag E and a water immersion expansion coefficient of less than 0.7%.
Claims (8)
（ｉ）製鋼スラグ（ａ）の一部について篩目が１０ｍｍ以下の篩（ｘ）で分級することで細粒・微粉分を減じた後、製鋼スラグ（ａ）の残部と混合する。
（ii）以前に、粒径４０ｍｍ以下の割合が８０mass％以上となる粒度に破砕され且つ該破砕後に加圧蒸気エージングが施された製鋼スラグを篩目が１０ｍｍ以下の篩（ｘ）で分級することで得られている細粒・微粉分を、製鋼スラグ（ａ）に加えて混合する。 A steelmaking slag that has been subjected to pressure steam aging after crushing to a particle size with a particle size of 40 mm or less to 80 mass% or more, and the particle size distribution is approximated by Andreazen's curve formula, Fuller index is 0.4 For steelmaking slag (a) that does not reach ~0.6, the grain size distribution of steelmaking slag (a) is approximated by Andreazen's curve formula by increasing or decreasing the fine grain/fine powder content under the conditions (i) or (ii) below. In this case, the particle size distribution of the steelmaking slag (a) is adjusted so that the Fuller index is 0.4 to 0.6.
(I) A part of the steelmaking slag (a) is classified with a sieve (x) having a mesh size of 10 mm or less to reduce fine particles and fine powders, and then mixed with the rest of the steelmaking slag (a).
(Ii) Classifying the steelmaking slag previously crushed to a particle size having a particle size of 40 mm or less to 80 mass% or more and subjected to pressurized steam aging after the crushing with a sieve (x) having a mesh size of 10 mm or less. The fine granules/fine powders thus obtained are added to the steelmaking slag (a) and mixed.
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