JP7047616B2 - How to make coke - Google Patents
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本発明は、製鉄原料として用いるコークスの製造方法に関するもので、特に、コークス粒度を向上させたコークスの製造方法に関する。 The present invention relates to a method for producing coke used as a raw material for steelmaking, and more particularly to a method for producing coke with an improved coke particle size.
高炉用コークスは、高炉内での通気・通液が確保されるようにするために、高強度であるとともに、粒径が大きいことが有利である。
近年では、高炉操業の安定化や、高炉でのコークス使用量の削減に対するニーズも高まっており、コークス粒度を向上させる方法の開発が求められている。
コークス粒度を向上させる方法としては、例えば、特許文献１、２に示されるような原料石炭に炭材を添加する方法が知られている。
It is advantageous that the coke for blast furnace has high strength and a large particle size in order to ensure ventilation and liquid passage in the blast furnace.
In recent years, there has been an increasing need for stabilizing blast furnace operation and reducing the amount of coke used in the blast furnace, and there is a need to develop a method for improving the coke particle size.
As a method for improving the coke particle size, for example, a method of adding a carbonaceous material to the raw material coal as shown in Patent Documents 1 and 2 is known.
特許文献１には、原料炭に粘結材とイナート物質（乾留時に軟化溶融しない炭材）を配合してこれを乾留することによりコークスを製造する際に、予め粘結材の添加量、イナート物質の粒径と添加量を変数として得られるコークスの粒径との関係を求めておき、目的とするコークス粒径に応じて、粘結材の添加量ならびにイナート物質の粒径および添加量を、求めておいた前記関係を用いて設定するコークスの製造方法が開示されている。
特許文献２には、配合炭に含まれる低収縮炭材を、サイズ区分に区分けし、低収縮炭材のサイズ区分別のコークス表面破壊強度およびコークス粒度への影響度をあらかじめ定めておき、目的とするコークスの粒径から低収縮炭材とその添加率を設定するとともに、低収縮炭材の添加によるコークス強度の低下代も同時に求めることにより、低下代を石炭の配合調整や粘結材の添加で補填するコークスの製造方法が開示されている。
In Patent Document 1, a binder and an inert substance (a carbon material that does not soften and melt during carbonization) are mixed with the coking coal, and the coke is produced by carbonization. The relationship between the particle size of the substance and the particle size of the coke obtained by using the amount of the substance added as a variable is obtained, and the amount of the binder added and the particle size and the amount of the carbonization substance added are determined according to the target coke particle size. , A method for producing coke set by using the above-mentioned relationship obtained is disclosed.
In Patent Document 2, the low-shrink coal material contained in the blended coal is classified into size categories, and the degree of influence on the coke surface breaking strength and the coke grain size for each size class of the low-shrink coal material is defined in advance. The low-shrinkage coal material and its addition rate are set from the grain size of the coke to be used, and the reduction allowance for the coke strength due to the addition of the low-shrinkage coal material is also obtained. A method for producing coke supplemented by addition is disclosed.
コークス粒径を拡大するために添加される炭材は、石炭の膨張による石炭粒子間の接着を阻害するとともに、石炭の収縮時に亀裂を発生させ、コークス強度を低下させる原因となる。特許文献２では、コークス強度の低下を抑制するために、石炭の配合調整や粘結材の添加などが必要になる。
そこで、本発明は、炭材を添加する方法を用いなくても、コークス強度を高め、さらにコークス粒度を向上させることができるコークスの製造方法を提供することを課題とする。
The coal material added to increase the coke grain size inhibits the adhesion between the coal particles due to the expansion of the coal, and also causes cracks during the shrinkage of the coal, which causes a decrease in the coke strength. In Patent Document 2, in order to suppress a decrease in coke strength, it is necessary to adjust the composition of coal and add a binder.
Therefore, an object of the present invention is to provide a method for producing coke, which can increase the coke strength and further improve the coke particle size without using the method of adding a carbonaceous material.
本発明者は、上記課題を解決すべく、原料石炭の粒度に着目して検討を進めた。その結果、コークス強度の向上とコークス粒度の向上をともに達成できる石炭の粒度範囲があることを見出した。
本発明は、そのような知見に基づいてなされたもので、その要旨とするところは以下の通りである。
In order to solve the above problems, the present inventor has focused on the particle size of the raw material coal and proceeded with the study. As a result, it was found that there is a grain size range of coal that can achieve both improvement of coke strength and improvement of coke grain size.
The present invention has been made based on such findings, and the gist thereof is as follows.
（１）原料石炭をコークス炉に装炭して乾留するコークスの製造方法において、
前記原料石炭から粗粒と微粉を除去して、粒度が０．３ｍｍ以上３ｍｍ未満からなる石炭を装炭するコークスの製造方法であって、
前記の粗粒と微粉を除去して送炭される石炭が、粒度が０．６ｍｍ以上２ｍｍ未満からなる石炭、粒度が０．３ｍｍ以上２ｍｍ未満からなる石炭、粒度が０．６ｍｍ以上３ｍｍ未満からなる石炭のいずれかであり、かつ、それぞれの石炭において、除去された微粉側の石炭により測定された収縮率Ｐと除去された粗粒側の石炭により測定された収縮率Ｑの比（Ｐ／Ｑ）が１．０６未満であることを特徴とするコークスの製造方法。
(1) In a method for producing coke in which raw coal is carbonized in a coke oven and carbonized.
A method for producing coke in which coarse particles and fine powder are removed from the raw material coal to charge coal having a particle size of 0.3 mm or more and less than 3 mm.
The coal to be sent by removing the coarse particles and fine powder is from coal having a particle size of 0.6 mm or more and less than 2 mm, coal having a particle size of 0.3 mm or more and less than 2 mm, and coal having a particle size of 0.6 mm or more and less than 3 mm. The ratio (P /) of the shrinkage rate P measured by the removed fine-grained coal and the shrinkage rate Q measured by the removed coarse-grained coal. A method for producing coke, characterized in that Q) is less than 1.06 .
（２）前記原料石炭を、ふるい目２ｍｍまたは３ｍｍのふるいを用いてふるい分けして、原料石炭からふるい上の粒度が２ｍｍ以上または３ｍｍ以上の石炭を除去し、ふるい下の粒度が２ｍｍ未満または３ｍｍ未満の石炭を得た後、前記ふるい下の粒度が２ｍｍ未満の石炭を流動床分級機に供給して、分級された粒度が０．３ｍｍ未満または０．６ｍｍ未満の微粉を除去し、粒度が０．６ｍｍ以上２ｍｍ未満からなる石炭または粒度が０．３ｍｍ以上２ｍｍ未満からなる石炭を得る、あるいは、前記ふるい下の粒度が３ｍｍ未満の石炭を流動床分級機に供給し、０．６ｍｍ未満の微粉を除去し、粒度が０．６ｍｍ以上３ｍｍ未満からなる石炭を得ることを特徴とする上記（１）に記載のコークスの製造方法。
( 2 ) The raw material coal is sifted using a sieve having a mesh size of 2 mm or 3 mm to remove coal having a particle size of 2 mm or more or 3 mm or more on the sieve from the raw material coal, and the particle size under the sieve is less than 2 mm or 3 mm. After obtaining less than Coal, the coal under the sieve having a particle size of less than 2 mm is supplied to the fluidized bed classifier to remove fine particles having a size of less than 0.3 mm or less than 0.6 mm. Coal having a particle size of 0.6 mm or more and less than 2 mm or coal having a particle size of 0.3 mm or more and less than 2 mm is obtained, or coal having a particle size of less than 3 mm under the sieve is supplied to the fluidized bed classifier and has a particle size of less than 0.6 mm. The method for producing coal according to ( 1 ) above, wherein fine powder is removed to obtain coal having a particle size of 0.6 mm or more and less than 3 mm.
（３）前記原料石炭を、流動床分級機に供給して、原料石炭から粒度が０．３ｍｍ未満または０．６ｍｍ未満の微粉を除去し、分級された粒度が０．３ｍｍ以上の石炭または０．６ｍｍ以上の石炭を得た後、前記分級された粒度が０．３ｍｍ以上の石炭をふるい目２ｍｍのふるいを用いてふるい分けして、ふるい上の粒度が２ｍｍ以上の石炭を除去し、粒度が０．３ｍｍ以上２ｍｍ未満からなる石炭を得る、あるいは、前記分級された粒度が０．６ｍｍ以上の石炭を、ふるい目２ｍｍまたは３ｍｍのふるいを用いてふるい分けして、ふるい上の粒度が２ｍｍ以上または３ｍｍ以上の石炭を除去し、粒度が０．６ｍｍ以上２ｍｍ未満からなる石炭または粒度が０．６ｍｍ以上３ｍｍ未満からなる石炭を得ることを特徴とする上記（１）に記載のコークスの製造方法。
( 3 ) The raw material coal is supplied to a liquid bed classifier to remove fine powder having a particle size of less than 0.3 mm or less than 0.6 mm from the raw material coal, and the classified coal having a particle size of 0.3 mm or more or 0. After obtaining coal of 6.6 mm or more, the classified coal having a grain size of 0.3 mm or more is sieved using a sieve having a mesh size of 2 mm to remove coal having a grain size of 2 mm or more on the sieve, and the grain size is changed. Coal consisting of 0.3 mm or more and less than 2 mm is obtained, or the classified coal having a grain size of 0.6 mm or more is sieved using a sieve having a sieve size of 2 mm or 3 mm, and the grain size on the sieve is 2 mm or more or The method for producing coal according to ( 1 ) above, wherein coal having a particle size of 3 mm or more is removed to obtain coal having a particle size of 0.6 mm or more and less than 2 mm or coal having a particle size of 0.6 mm or more and less than 3 mm.
本発明によれば、特定粒度範囲の石炭のみを使用することにより、強度と粒度がともに向上したコークスを得ることができる。 According to the present invention, by using only coal in a specific particle size range, coke having improved strength and particle size can be obtained.
一般に、粉砕された原料石炭の粗粒部分には、硬い組織であるイナート組織が濃縮されやすい。粗大なイナート組織は、クラック（微小亀裂）発生の原因となるためコークス強度を低下させることが知られている。
一方、微粉部分には、軟らかい組織であるビトリニットが濃縮されやすい。このビトリニットは軟化溶融する組織ではあるが、微粒子になりすぎると、軟化溶融性が発現せず、逆に周囲の膨張性を阻害する要因になり、やはりコークス強度を低下させることが知られている。
また、微粉部分の収縮率は原料石炭の平均より高いため、原料石炭に微粒部分が入っているとコークス粒度が低下する要因になると考えた。
そこで、コークス強度およびコークス粒度の向上を阻害する石炭の粒度範囲を除外し、残りの範囲の中から、コークス強度およびコークス粒度の向上に寄与する範囲を選択することを検討した結果、コークス強度の向上とコークス粒度の向上をともに達成できる石炭の粒度範囲があることを見出し、本発明に到達した。
In general, the inert structure, which is a hard structure, is likely to be concentrated in the coarse-grained portion of the crushed raw material coal. It is known that the coarse inert structure causes the generation of cracks (micro-cracks) and thus reduces the coke strength.
On the other hand, vitrinit, which is a soft tissue, is likely to be concentrated in the fine powder portion. Although this vitrinit is a structure that softens and melts, it is known that if it becomes too fine particles, the softening and melting property does not develop, and conversely, it becomes a factor that hinders the swelling of the surroundings and also lowers the coke strength. ..
In addition, since the shrinkage rate of the fine powder portion is higher than the average of the raw material coal, it is considered that the coke grain size may be lowered if the raw material coal contains the fine particle portion.
Therefore, as a result of considering excluding the grain size range of coal that hinders the improvement of coke strength and coke grain size and selecting the range that contributes to the improvement of coke strength and coke grain size from the remaining range, the coke strength We have found that there is a grain size range of coal that can achieve both improvement and improvement of coke grain size, and arrived at the present invention.
以下、そのようになされた本発明について実験的な知見を含め説明する。なお、含有量についての「％」は「質量％」を示す。 Hereinafter, the present invention made in such a manner will be described including experimental findings. In addition, "%" about the content indicates "mass%".
（実験１）
粒度分布が異なる石炭を用いてコークスを製造し、コークス粒度及びコークス強度への影響を調べた。
表１に示す性状の石炭Ｆを準備した。なお、揮発分含有量はドライベースの値を示す。この石炭Ｆを、３ｍｍふるい下８５質量％に粉砕し、得られた粉砕後の石炭の一部をふるい目３ｍｍでふるい分けし、ふるい上の３ｍｍ以上（＋３ｍｍ）の石炭を除去し、ふるい下の３ｍｍ未満（－３ｍｍ）の石炭をさらに分級して０．３ｍｍ未満（－０．３ｍｍ）の微粉を除去した。得られた中間粒度の石炭の一部を、さらに分級やふるい分けして、さらに狭い粒度範囲の石炭を得た。
これによって、表２に示すとおりの、粉砕したままの石炭（条件１）、粒度０．３ｍｍ以上３．０ｍｍ未満の中間粒度を有する石炭（条件２）、粒度０．６ｍｍ以上２．０ｍｍ未満の中間粒度を有する石炭（条件３）の３条件の石炭試料を得た。
(Experiment 1)
Coke was produced using coal with different particle size distributions, and the effects on coke particle size and coke strength were investigated.
Coal F having the properties shown in Table 1 was prepared. The volatile content is a dry base value. This coal F is crushed to 85% by mass under a 3 mm sieve, and a part of the obtained crushed coal is sieved by a sieve of 3 mm to remove 3 mm or more (+ 3 mm) of coal on the sieve and under the sieve. Coal less than 3 mm (-3 mm) was further classified to remove fines less than 0.3 mm (−0.3 mm). A part of the obtained intermediate grain size coal was further classified and screened to obtain a coal having a narrower grain size range.
As a result, as shown in Table 2, coal as crushed (Condition 1), coal with an intermediate particle size of 0.3 mm or more and less than 3.0 mm (Condition 2), and coal with a particle size of 0.6 mm or more and less than 2.0 mm. A coal sample under three conditions of coal having an intermediate particle size (condition 3) was obtained.
条件１～３の石炭試料をそれぞれ試験コークス炉で乾留し、乾留後のコークスを窒素中で冷却した後、コークス平均粒度とコークス強度ＤＩを測定した。
ここで、コークス平均粒度は、複数の篩目で篩を行い、篩目の各粒度区分ごとの質量を測定し、各粒度区分の代表径（上下の篩目の中間径）を用いて、当該粒度区分の質量比率で加重平均した値とした。また、コークス強度ＤＩとしては、ドラム強度指数ＤＩ150
15（以降、単に「ＤＩ」と記載する場合がある。）を測定した。
その結果を表２に示す。
The coal samples under conditions 1 to 3 were carbonized in a test coke oven, and the coke after carbonization was cooled in nitrogen, and then the average coke grain size and the coke intensity DI were measured.
Here, the coke average particle size is determined by sieving with a plurality of meshes, measuring the mass of each particle size category of the mesh, and using the representative diameter of each particle size category (intermediate diameter of the upper and lower meshes). The value was weighted and averaged by the mass ratio of the particle size classification. Further, as the coke intensity DI, the drum intensity index DI 150 15 (hereinafter, may be simply referred to as “DI”) was measured.
The results are shown in Table 2.
原料石炭から中間粒度の石炭のみを選んで乾留した条件２、条件３のコークスでは、粉砕したままの石炭を乾留した条件１のコークスに比べると、コークス平均粒度、コークス強度ＤＩともに向上した。
この場合、条件２の粒度範囲０．３－３．０ｍｍでも十分効果が認められたが、条件３の粒度範囲０．６－２．０ｍｍでは、さらにコークス平均粒度、ＤＩともに向上することが認められた。
In the coke of conditions 2 and 3 in which only intermediate grain size coal was selected from the raw material coal and carbonized, both the coke average grain size and the coke strength DI were improved as compared with the coke in condition 1 in which the crushed coal was carbonized.
In this case, a sufficient effect was observed even in the particle size range of 0.3-3.0 mm in condition 2, but it was confirmed that both the coke average particle size and DI were further improved in the particle size range of 0.6-2.0 mm in condition 3. Was done.
原料石炭のうちの中間粒度の石炭のみを乾留することで、強度が高く、粒度が大きいコークスが製造できる理由は、以下のように考えられる。 The reason why coke with high strength and large particle size can be produced by carbonizing only intermediate grain size coal among the raw material coal is considered as follows.
一般に、原料石炭の粗粒部分には、硬い組織であるイナート組織が濃縮されやすい。特に、粒度が３ｍｍ以上の石炭粒子には大きなイナート組織が含まれる。大きなイナート組織は、クラック（微小亀裂）発生の原因となるためコークス強度を低下させる。 In general, the inert structure, which is a hard structure, is likely to be concentrated in the coarse grain portion of the raw material coal. In particular, coal particles having a particle size of 3 mm or more contain a large inert structure. A large inert structure causes the occurrence of cracks (microcracks) and thus reduces the coke strength.
一方、微粉部分には、軟らかい組織であるビトリニットが濃縮される。このビトリニットは軟化溶融する組織ではあるが、微粒子になりすぎると軟化溶融性が発現せず、逆に周囲の膨張性を阻害する。
これは、石炭粒子のサイズが小さいと、個々の粒子からガスが抜けやすくなるために、粒子そのものが膨張しにくくなること、また、粒子が小さいと比表面積が増加し、粒子の周囲からガスが抜けるための抜け道が増えて、周囲の膨張性を阻害するためコークス強度を低下させる。
さらに、微粉部分の収縮率は原料石炭の平均より高いため、微粉部分が入っているとコークス粒度が低下する要因になると考えられる。
On the other hand, vitrinit, which is a soft tissue, is concentrated in the fine powder portion. This vitrinit is a structure that softens and melts, but if it becomes too fine particles, softening and melting properties do not develop, and conversely, the expansion of the surroundings is hindered.
This is because when the size of coal particles is small, gas easily escapes from individual particles, which makes it difficult for the particles themselves to expand, and when the particles are small, the specific surface area increases and gas is released from around the particles. There are more loopholes for exiting, which hinders the swelling of the surroundings and reduces coke strength.
Furthermore, since the shrinkage rate of the fine powder portion is higher than the average of the raw material coal, it is considered that the inclusion of the fine powder portion causes a decrease in the coke particle size.
条件２、３では、３ｍｍ以上の石炭粒子を除去した結果、上記のように、ＤＩへの悪影響が大きい粗大なイナート組織の量を条件１より低下させ、さらに、コークス強度およびコークス粒度の両方が低下する要因になる粒度０．３ｍｍ未満の微粉が除去されたので、条件１に比較してコークス強度およびコークス平均粒度が向上したと考えられる。 Under conditions 2 and 3, as a result of removing coal particles of 3 mm or more, as described above, the amount of coarse inert structure having a large adverse effect on DI is reduced from that of condition 1, and both coke strength and coke particle size are increased. It is considered that the coke strength and the average coke particle size were improved as compared with the condition 1 because the fine particles having a particle size of less than 0.3 mm, which was a factor for the decrease, were removed.
次に、この実験で、条件３が条件２よりさらにコークス平均粒度とＤＩが向上した結果が得られたので、これらがより向上する石炭の条件についても検討した。 Next, in this experiment, the results that the coke average particle size and DI were further improved in the condition 3 than in the condition 2 were obtained, and the conditions of the coal in which these were further improved were also examined.
（実験２）
石炭として、先の石炭Ｆと表３に示す性状の石炭Ｇを用いて、それぞれの石炭についてより好ましい粒度範囲の条件を調べた。
(Experiment 2)
As the coal, the above coal F and the coal G having the properties shown in Table 3 were used, and the conditions of a more preferable particle size range were investigated for each coal.
まず、石炭Ｆ、Ｇを、３ｍｍふるい下８５％に粉砕し、得られた粉砕後の石炭の一部をふるい目３ｍｍでふるい分けし、＋３ｍｍの石炭を除去し、ふるい下の－３ｍｍの石炭をさらに分級して、－０．３ｍｍの石炭を除去した石炭と０．６ｍｍ未満（－０．６ｍｍ）の石炭を除去した石炭を採取し、これら採取した石炭から、２ｍｍふるい上（＋２ｍｍ）の石炭を除去した石炭を採取した。
これにより、先の実験１の、条件２：粒度が０．３ｍｍ以上３ｍｍ未満の石炭と、条件３：粒度が０．６ｍｍ以上２ｍｍ未満の石炭に加え、それらの中間の粒度を有する下記の条件４、５の石炭をさらに準備した。
条件４：粒度が０．３ｍｍ以上２ｍｍ未満の石炭
条件５：粒度が０．６ｍｍ以上３ｍｍ未満の石炭
First, coals F and G are crushed to 85% under a 3 mm sieve, a part of the obtained crushed coal is sieved with a 3 mm sieve, + 3 mm coal is removed, and -3 mm coal under the sieve is removed. Further classification is performed to collect coal from which -0.3 mm of coal has been removed and coal from which coal of less than 0.6 mm (-0.6 mm) has been removed. The coal from which was removed was collected.
As a result, in addition to the condition 2: coal having a particle size of 0.3 mm or more and less than 3 mm and the condition 3: coal having a particle size of 0.6 mm or more and less than 2 mm in the previous experiment 1, the following conditions having an intermediate particle size between them. Further preparations of 4 and 5 coals were made.
Condition 4: Coal with a particle size of 0.3 mm or more and less than 2 mm Condition 5: Coal with a particle size of 0.6 mm or more and less than 3 mm
条件１～５の石炭試料をそれぞれ試験コークス炉で乾留し、乾留後のコークスを窒素中で冷却した後、コークス平均粒度とコークス強度ＤＩ（ドラム強度指数ＤＩ150 15）を測定した。結果を表４に示す。なお、石炭Ｆの条件１～３は実験１の結果を用いた。 The coal samples under conditions 1 to 5 were carbonized in a test coke oven, and the coke after carbonization was cooled in nitrogen, and then the average coke grain size and the coke intensity DI (drum intensity index DI 150 15 ) were measured. The results are shown in Table 4. The results of Experiment 1 were used for conditions 1 to 3 of coal F.
石炭Ｆ、Ｇのいずれにおいても、条件３～５の石炭について、条件２の石炭よりさらにコークス平均粒度、ＤＩがともに向上する結果が得られた。これは、狭い粒度範囲にすることにより、粗大なイナート組織や微粉の量がさらに低下したためと考えられる。
しかし、石炭Ｆでは、粒度範囲の条件３～５の石炭で、条件２よりも大きな向上効果が得られたが、石炭Ｇでは石炭Ｆほどの大きな向上効果は得られなかった。
In both of the coals F and G, the coke average particle size and DI were further improved for the coals under the conditions 3 to 5 as compared with the coal under the condition 2. It is considered that this is because the amount of coarse inert structure and fine powder was further reduced by setting the particle size range to a narrow range.
However, in the case of coal F, the improvement effect of coal under the condition 3 to 5 in the particle size range was larger than that of condition 2, but the improvement effect of coal G was not as large as that of coal F.
以上の実験で、石炭銘柄によって、狭い粒度範囲にした場合のコークス平均粒度とＤＩの向上効果に差が出ることが知見されたため、向上効果が得られる条件についてさらに検討した。
検討にあたり、石炭を乾留する際のコークス収縮率に着目した。コークス収縮率は、得られるコークスの強度や粒径に影響を与えることが知られており、種々の粒度範囲の石炭について、コークス収縮率とコークスの強度や粒径との関係を調べた。
その結果、中間粒度範囲から除去された石炭について、微粉側の石炭の収縮率と粗粒側の石炭の収縮率との比が、コークス平均粒度、ＤＩの向上に影響を与えることを知見した。
以下、条件２～５について、中間粒度範囲から除去された石炭の収縮率について検討した結果を示す。
In the above experiments, it was found that there is a difference between the average coke grain size and the DI improvement effect when the grain size range is narrowed depending on the coal brand, so the conditions under which the improvement effect can be obtained were further investigated.
In the examination, we focused on the coke shrinkage rate when carbonizing coal. It is known that the coke shrinkage rate affects the strength and particle size of the obtained coke, and the relationship between the coke shrinkage rate and the coke strength and particle size was investigated for coal in various particle size ranges.
As a result, it was found that the ratio of the shrinkage ratio of the coal on the fine powder side to the shrinkage ratio of the coal on the coarse grain side affects the improvement of the coke average particle size and DI for the coal removed from the intermediate particle size range.
Hereinafter, the results of examining the shrinkage rate of coal removed from the intermediate particle size range under conditions 2 to 5 are shown.
まず、中間粒度の石炭から除去される微粉側の石炭として、粉砕した石炭から粒度０．３ｍｍ未満（－０．３ｍｍ）の石炭と０．６ｍｍ未満（－０．６ｍｍ）の石炭を採取するとともに、同じく除去される粗粒側の石炭として、粉砕した石炭から粒度２ｍｍ以上（＋２ｍｍ）の石炭と３ｍｍ以上（＋３ｍｍ）の石炭を採取して、それぞれの石炭の収縮率を調べた。それぞれの粒度の石炭の収縮率を表５に示す。 First, coal with a grain size of less than 0.3 mm (-0.3 mm) and coal with a grain size of less than 0.6 mm (-0.6 mm) are sampled from the crushed coal as the coal on the fine powder side to be removed from the coal with an intermediate grain size. As the coarse-grained coal to be removed, coal having a particle size of 2 mm or more (+2 mm) and coal having a particle size of 3 mm or more (+3 mm) were collected from the crushed coal, and the shrinkage ratio of each coal was examined. Table 5 shows the shrinkage rate of coal of each particle size.
コークス収縮率は、特開２００５－２３２３４９号公報に記載の方法、すなわち、石炭を容器内において石炭の再固化温度以上の温度Ｔ（℃）まで加熱し、再固化温度と温度Ｔとにおける内容物の容積差又は長さ差を再固化温度における容積又は長さで除した値をその石炭から生成したコークスの温度Ｔにおける収縮率とする方法で求めた。温度Ｔは、１０００℃とした。 The coke shrinkage is determined by the method described in JP-A-2005-232349, that is, the coal is heated in a container to a temperature T (° C.) equal to or higher than the resolidification temperature of the coal, and the contents at the resolidification temperature and the temperature T. The value obtained by dividing the difference in volume or difference in length by the volume or length at the solidification temperature was used as the shrinkage rate of coke produced from the coal at the temperature T. The temperature T was 1000 ° C.
次に、条件２～５のそれぞれで除去された微粉側の石炭の収縮率Ｐと粗粒側の石炭の収縮率Ｑの比（Ｐ／Ｑ）を調べた。例えば、条件２では、収縮率Ｐ：粒度－０．３ｍｍの収縮率、収縮率Ｑ：粒度＋３ｍｍの収縮率とする。結果を表６に示す。
表６から、石炭Ｆでは条件３～５で除外された石炭の収縮率比が条件２に比べて低下しているが、石炭Ｇでは条件３～５の収縮率比が条件２の収縮率比と同じであることがわかる。
この結果から、除去された微粉側の石炭により測定された収縮率Ｐと除去された粗粒側の石炭により測定された収縮率Ｑの比（Ｐ／Ｑ）が１．０６未満であれば、より狭い中間粒度の石炭を用いて製造したコークス粒径、強度ともに増加することが判明した。
Next, the ratio (P / Q) of the shrinkage ratio P of the coal on the fine powder side and the shrinkage ratio Q of the coal on the coarse grain side removed under each of the conditions 2 to 5 was investigated. For example, under condition 2, the shrinkage rate P: the shrinkage rate of −0.3 mm, and the shrinkage rate Q: the shrinkage rate of +3 mm. The results are shown in Table 6.
From Table 6, in coal F, the shrinkage ratio of coal excluded in conditions 3 to 5 is lower than that in condition 2, but in coal G, the shrinkage ratio of conditions 3 to 5 is the shrinkage ratio of condition 2. It turns out that it is the same as.
From this result, if the ratio (P / Q) of the shrinkage ratio P measured by the removed fine powder side coal and the shrinkage ratio Q measured by the removed coarse grain side coal is less than 1.06, It was found that both the coke grain size and the strength produced using coal with a narrower intermediate grain size increased.
本発明者らは、以上の実験を基礎として、さらに、異なる銘柄の種々の石炭やそれらを配合した配合炭について、同様の試験を行い、粒度が０．３ｍｍ以上３ｍｍ未満の石炭のみを乾留することにより、コークス強度とコークス平均粒度をともに向上したコークスを製造できることを確認することができた。さらには、条件３～５のような、より狭い粒度範囲の石炭を用いた場合、除去された微粉側の石炭の収縮率と除去された粗粒側の石炭の収縮率の比が１．０６未満となることが好ましいことも確認した。 Based on the above experiments, the present inventors further perform similar tests on various coals of different brands and blended coals containing them, and dry-distill only coal having a particle size of 0.3 mm or more and less than 3 mm. As a result, it was confirmed that coke with improved coke strength and average coke grain size could be produced. Furthermore, when coal with a narrower particle size range such as conditions 3 to 5 is used, the ratio of the shrinkage ratio of the removed fine-grained coal to the removed coarse-grained coal is 1.06. It was also confirmed that it is preferable that it is less than.
以下、そのような本発明を構成する個々の条件や好ましい条件についてさらに説明する。
（石炭）
コークス用の原料石炭としては、粉砕後に粗粒と微粉を除去して用いるが、もともと粉粒状の石炭は粉砕することなく粗粒と微粉を除去して用いることができる。
使用される石炭の銘柄としては、特に限定されるものではなく、強粘結炭を含む通常の配合炭用の石炭を用いることができる。
粉砕する場合の石炭の粉砕粒度は、－３ｍｍが７０～９０％に粉砕されたものが使用できる。この範囲であれば、特に石炭の銘柄によらず効果を発揮できる。
Hereinafter, the individual conditions and preferable conditions constituting such the present invention will be further described.
(coal)
As the raw material coal for coke, coarse grains and fine powder are removed after crushing, but originally powdery granular coal can be used by removing coarse grains and fine powder without crushing.
The brand of coal used is not particularly limited, and ordinary coal for compound coal including strong caking coal can be used.
As the crushing particle size of coal for crushing, -3 mm crushed to 70 to 90% can be used. Within this range, the effect can be exhibited regardless of the brand of coal.
配合炭としては、複数の銘柄の石炭を個々に粉砕し、銘柄ごとに中間粒度に分級・ふるい分けし、得られた中間粒度の石炭を配合したものでも、複数の銘柄の石炭を先に配合してから粉砕し、粉砕後の石炭を中間粒度に分級・ふるい分けしたものでもよい。
本発明では、石炭を粉砕後に粗粒と微粉を除去する場合、粉砕前の石炭を－３ｍｍが７０～８５質量％に粉砕した際に、最大長さが１．５ｍｍ以上の大きなイナート組織の比率が５体積％以上の石炭の方が、より大きな効果が発揮できる。
As the blended coal, multiple brands of coal are individually crushed, classified and screened into intermediate particle sizes for each brand, and even if the obtained intermediate grain size coal is blended, multiple brands of coal are blended first. The coal may be crushed after being crushed, and the crushed coal may be classified and sieved to an intermediate particle size.
In the present invention, when coarse particles and fine powder are removed after crushing coal, the ratio of large inert structure having a maximum length of 1.5 mm or more when -3 mm is crushed to 70 to 85% by mass of coal before crushing. Coal with a volume of 5% by volume or more can exert a greater effect.
本発明では、コークス炉に送炭する石炭として、粉粒状の石炭や粉砕された石炭から粒度が０．３ｍｍ以上３ｍｍ未満の石炭を用いる。粒度が０．６ｍｍ以上２ｍｍ未満からなる石炭、粒度が０．６ｍｍ以上３ｍｍ未満からなる石炭、粒度が０．３ｍｍ以上２ｍｍ未満からなる石炭のいずれかであって、それぞれの粒度において除去された微粉側の石炭により測定された収縮率Ｐと除去された粗粒側の石炭により測定された収縮率Ｑの比（Ｐ／Ｑ）が１．０６未満である石炭を用いれば、より効果が向上するため好ましい。 In the present invention, as the coal to be sent to the coke oven, coal having a particle size of 0.3 mm or more and less than 3 mm from pulverized coal or crushed coal is used. Coal with a particle size of 0.6 mm or more and less than 2 mm, coal with a particle size of 0.6 mm or more and less than 3 mm, or coal with a particle size of 0.3 mm or more and less than 2 mm, and fine powder removed at each particle size. If the ratio (P / Q) of the shrinkage ratio P measured by the side coal to the shrinkage ratio Q measured by the removed coarse grain side coal is less than 1.06, the effect is further improved. Therefore, it is preferable.
（製造方法）
本発明の実施に当たり、粗粒部分と微粉部分を除去する方法は数多く考えられるが、一例として図１ａ及び図１ｂに示すフローに基づいて選別する方法について説明する。
(Production method)
In carrying out the present invention, there are many conceivable methods for removing the coarse grain portion and the fine powder portion, and as an example, a method for sorting based on the flows shown in FIGS. 1a and 1b will be described.
図１ａのフローでは、粉砕された配合炭を、まず、ふるい目３ｍｍのふるいを用いてふるい分けして、配合炭からふるい上の＋３ｍｍの石炭を除去し、ふるい下の－３ｍｍの石炭を流動床分級機に供給し、分級された－０．３ｍｍの微粉を除去し、中間粒度（粒度０．３－３ｍｍ）の配合炭を得る。なお、粉砕された配合炭から、ふるい目３ｍｍのふるいを用いてふるい分けを行う前に、配合炭を事前に乾燥させて水分を低下させることで、ふるいが行い易くなるため好ましい。この水分値としては、５質量％以下とすることが例示される。
図１ｂのフローでは、配合炭を、先に流動床分級機に供給して、配合炭から－０．３ｍｍの微粉を除去し、次に、分級された＋０．３ｍｍの石炭を、ふるい目３ｍｍでふるい分けし、ふるい上の＋３ｍｍの石炭を除去し、中間粒度（粒度０．３－３ｍｍ）の配合炭を得る。
In the flow of FIG. 1a, the crushed compound coal is first sifted using a sieve with a sieve mesh of 3 mm to remove + 3 mm of coal on the sieve from the compound coal, and -3 mm of coal under the sieve is placed on the fluidized bed. It is supplied to a classifier, and the classified -0.3 mm fine powder is removed to obtain a compound coal having an intermediate particle size (grain size 0.3-3 mm). It is preferable to dry the mixed coal in advance to reduce the water content before sieving the crushed mixed coal using a sieve having a sieve mesh of 3 mm, because the sieving becomes easier. The moisture value is exemplified to be 5% by mass or less.
In the flow of FIG. 1b, the blended coal is first supplied to the fluidized bed classifier to remove -0.3 mm fine powder from the blended coal, and then the classified + 0.3 mm coal is sieved to 3 mm. Sift with a sieve and remove + 3 mm of coal on the sieve to obtain a compound coal with an intermediate particle size (grain size 0.3-3 mm).
より好ましい粒度範囲として、中間粒度（０．６－２ｍｍ）の石炭を選別するには、図１ａのフローでは、最初のふるい分けの時に、ふるい目２ｍｍのふるいを用いる、また、ふるい下の－２ｍｍの石炭を流動床分級機で分級する際に－０．６ｍｍの微粉を除去するようにすればよい。
また、図１ｂのフローでは、最初に流動床分級機で分級する際に－０．６ｍｍの微粉を除去する、ふるい分けの時に、ふるい目２ｍｍのふるいを用いる、また、分級後の石炭をふるい分けする際、ふるい目２ｍｍのふるいを用いるようにすればよい。
なお、より好ましい別の粒度範囲として、中間粒度（０．３－２ｍｍ）、中間粒度（０．６－３ｍｍ）の石炭を選別する場合は、それぞれ、ふるい目および分級点を調整して用いるようにすればよい。
As a more preferred particle size range, to sort coal with an intermediate particle size (0.6-2 mm), in the flow of FIG. 1a, a sieve with a sieve mesh of 2 mm is used during the first sieving, and -2 mm below the sieve. When classifying coal with a fluidized bed classifier, -0.6 mm of fine powder may be removed.
Further, in the flow of FIG. 1b, the fine powder of −0.6 mm is removed at the time of first classification by the fluidized bed classifier, a sieve with a sieve of 2 mm is used at the time of sieving, and the coal after classification is sieved. At that time, a sieve having a sieve mesh of 2 mm may be used.
As another more preferable particle size range, when selecting coal having an intermediate particle size (0.3-2 mm) and an intermediate particle size (0.6-3 mm), the sieve mesh and the classification point should be adjusted and used, respectively. It should be.
（その他）
本発明で対象とする粒度範囲の石炭の製造過程で生じた粒度３ｍｍ以上の石炭（＋３ｍｍ部分）および粒度０．３ｍｍ未満の石炭（－０．３ｍｍ部分）は、別の配合炭にまぜて活用することができる。高炉にはさまざまなコークスが求められており、高強度・大粒径コークスだけでなく、例えば、高炉の焼結鉱層内に混合するコークスなどは、強度および粒度ともに相対的に低いものでも使用できる。
石炭の＋３ｍｍ部分は、そのままあるいは粉砕して、他の配合炭にまぜてコークス炉に装入すればよい。また、－０．３ｍｍ部分は、そのままでは発塵等の原因になるので、バインダーを添加して混練するか、混練した後に塊成化し、混練物あるいは塊成物を他の配合炭と混ぜてコークス炉に装入すればよい。
より好ましい粒度範囲を選択した場合でも、粗粒側、微分側の石炭と同様に取り扱えばよい。
(others)
Coal with a particle size of 3 mm or more (+3 mm portion) and coal with a particle size of less than 0.3 mm (-0.3 mm portion) produced in the process of manufacturing coal in the particle size range targeted by the present invention are mixed with another compound coal and utilized. can do. Various types of coke are required for blast furnaces, and not only high-strength and large-particle size coke, but also coke mixed in the sinter layer of the blast furnace, for example, can be used even if the strength and particle size are relatively low. ..
The + 3 mm portion of coal may be mixed with other blended coal as it is or crushed and charged into a coke oven. In addition, since the -0.3 mm portion may cause dust generation as it is, add a binder and knead it, or after kneading it, agglomerate it and mix the kneaded product or agglomerated product with other compounded coal. All you have to do is charge it into a coke oven.
Even when a more preferable particle size range is selected, it may be handled in the same manner as coal on the coarse grain side and the differential side.
Claims (3)
前記原料石炭から粗粒と微粉を除去して、粒度が０．３ｍｍ以上３ｍｍ未満からなる石炭を装炭するコークスの製造方法であって、
前記の粗粒と微粉を除去して送炭される石炭が、粒度が０．６ｍｍ以上２ｍｍ未満からなる石炭、粒度が０．３ｍｍ以上２ｍｍ未満からなる石炭、粒度が０．６ｍｍ以上３ｍｍ未満からなる石炭のいずれかであり、かつ、それぞれの石炭において、除去された微粉側の石炭により測定された収縮率Ｐと除去された粗粒側の石炭により測定された収縮率Ｑの比（Ｐ／Ｑ）が１．０６未満であることを特徴とするコークスの製造方法。 In the method of manufacturing coke, in which raw coal is carbonized in a coke oven and carbonized.
A method for producing coke in which coarse particles and fine powder are removed from the raw material coal to charge coal having a particle size of 0.3 mm or more and less than 3 mm.
The coal to be sent by removing the coarse particles and fine powder is from coal having a particle size of 0.6 mm or more and less than 2 mm, coal having a particle size of 0.3 mm or more and less than 2 mm, and coal having a particle size of 0.6 mm or more and less than 3 mm. The ratio (P /) of the shrinkage rate P measured by the removed fine-grained coal and the shrinkage rate Q measured by the removed coarse-grained coal. A method for producing coke, characterized in that Q) is less than 1.06 .
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| JP2010138254A (en) | 2008-12-10 | 2010-06-24 | Nippon Steel Corp | Method of manufacturing coke for blast furnace |
| CN106635069A (en) | 2016-10-27 | 2017-05-10 | 武汉科技大学 | Method for utilizing low-temperature waste heat of circulating gas in coke dry quenching system |
| CN106675601A (en) | 2016-10-27 | 2017-05-17 | 武汉科技大学 | Dry quenching circulating gas and coke-oven flue gas waste heat coupling utilization method |
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| JPS5454102A (en) * | 1977-10-07 | 1979-04-28 | Nippon Steel Corp | Classification and selective crushing of coal for coke manufacturing |
| JP3488014B2 (en) * | 1996-04-03 | 2004-01-19 | 関西熱化学株式会社 | Processing method of gas used for high temperature preheating of coal |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009270104A (en) | 2008-04-09 | 2009-11-19 | Nippon Steel Corp | Coke manufacturing method |
| JP2010138254A (en) | 2008-12-10 | 2010-06-24 | Nippon Steel Corp | Method of manufacturing coke for blast furnace |
| CN106635069A (en) | 2016-10-27 | 2017-05-10 | 武汉科技大学 | Method for utilizing low-temperature waste heat of circulating gas in coke dry quenching system |
| CN106675601A (en) | 2016-10-27 | 2017-05-17 | 武汉科技大学 | Dry quenching circulating gas and coke-oven flue gas waste heat coupling utilization method |
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