【発明の詳細な説明】[Detailed description of the invention]
本発明は、原料炭の予熱乾燥時に発生し、集塵
機によつて回収される微粉炭の処理方法に関する
ものである。
予熱・乾燥炭装入法は、石炭を80〜300℃に予
熱・乾燥してコークス炉に装入する技術で、通常
の湿式装入法に比較し、装入嵩密度が上昇し、コ
ークス生産性が向上すること、コークス強度が上
昇するので劣質炭の一部使用が可能となることが
知られている。
しかし、コークス炉に予熱・乾燥炭を装入する
と、発生ガスに同伴される炭塵が湿式装入法に比
較して増大するばかりでなく、予熱・乾燥時に集
塵機により補捉・回収される微粉炭の処理が困難
であることも知られている。
すなわち、流動炉、気流乾燥炉等を使用する熱
風による直接加熱方式においては、３mm以下80〜
90％に粉砕された石炭粒子を上記流動炉等により
直接加熱する場合、凝似粒子化していた微粉炭が
気流によつて分散する。この微粉炭は、サイクロ
ン、電気集塵機等で捕捉回収されるのであるが、
サイクロンによる捕集後の排気に同伴される150
ミクロン以下の微粉炭は、電気集塵機等で回収さ
れる。
この電気集塵機等で回収される微粉炭は、予熱
乾燥処理量の0.4〜0.6％程度であるが、予熱乾燥
炭に混合し、そのままコークス炉に搬送して装入
しても、装入時に再飛散して発生ガスに同伴さ
れ、またはコークス炉壁にカーボンとして附着す
る等、コークス炉の操業に支障をきたすのでその
ままコークス炉に装入することはできない。
この予熱乾燥時の回収微粉炭の処理方法として
は、石炭予熱処理工程にて回収される100ミクロ
ン以下の微粉炭を、タール、重油等液状の添加剤
に混合し、混合物の粘度を100センチポイズ以下
の範囲に調整してスラリー状添加剤となし、これ
を予熱炭混合機において予熱配合炭に添加混合す
ることを特徴とする予熱炭装入を行うコークス炉
における微粉炭処理方法（特開昭54−134703）等
の提案が行なわれている。
本発明は、石炭の予熱乾燥処理工程の電気集塵
機で捕捉回収される乾燥状態の微粉炭を水分８〜
10％の湿炭に混合し、混合炭の水分を５％以上に
調整した後、成型原料炭に添加混合し、加圧成型
して成型炭とすることを特徴とする原料炭予熱乾
燥時の回収微粉炭の処理方法である。前記電気集
塵機によつて捕捉回収した微粉炭を、水分８〜10
％の湿炭と混合して水分５〜10％に調整すること
によつて搬送時の発塵が防止されると共に、成型
原料炭に添加混練し、加圧成型して成型炭とする
ことによりコークス炉へ装入時の再飛散が防止さ
れ、微粉炭の発生ガスへの同伴、またはコークス
炉壁にカーボンとして附着することが皆無となる
のである。
なお、電気集塵機によつて捕捉回収した乾燥状
態の微粉炭を湿炭と混合した混合炭の水分を５％
以上としたのは、混合炭の水分が５％以下では搬
送時乗継部等で発塵するばかりでなく、成型原料
炭に添加時発塵するため、５％以上の水分が必要
である。また、調湿原料となる湿炭の水分は８〜
10％であるため、混合炭の水分は10％を超えるこ
とはない。また、微粉炭を湿炭と混合して成型原
料炭に混合するのは、湿炭と混合せず成型原料炭
に添加混合する場合は、回収微粉炭は極めて微粒
であるため、その発塵により取扱いが困難である
からである。
さらに上記混合炭を混合する成型原料炭は、湿
炭に限らず、乾燥予熱炭であつても、量的に見た
場合、混合炭は成型原料炭の５％程度であり、何
ら悪影響を与えることはない。
実施例 １
流動炉を用いた石炭の予熱処理工程のサイクロ
ンの後の電気集塵機で捕捉回収した150ミクロン
以下の微粉炭（水分０％）と水分８％の湿炭を混
合して水分３〜６％の混合炭を調整し、各混合炭
をベルトコンベアーで搬送してコンベアーの乗継
部すなわちシユート部における発塵状況を目視観
察した。その結果を第１表に示す。
The present invention relates to a method for treating pulverized coal generated during preheating and drying of raw coal and collected by a dust collector. The preheating/dry coal charging method is a technology in which coal is preheated to 80 to 300°C, dried, and then charged into a coke oven.Compared to the normal wet charging method, the charging bulk density increases and coke production is improved. It is known that coke strength is improved and coke strength is increased, making it possible to use some inferior quality coal. However, when preheating and drying coal is charged into a coke oven, not only does the coal dust that accompanies the generated gas increase compared to the wet charging method, but also the fine powder that is captured and collected by the dust collector during preheating and drying. It is also known that charcoal is difficult to process. In other words, in the direct heating method using hot air using a fluidized bed furnace, flash drying furnace, etc., the
When coal particles that have been pulverized to 90% are directly heated in the fluidized bed furnace or the like, the pulverized coal that has become agglomerated particles is dispersed by the air current. This pulverized coal is captured and recovered using cyclones, electrostatic precipitators, etc.
150 entrained in exhaust air after collection by cyclone
Pulverized coal of micron size or less is collected using an electrostatic precipitator or the like. The amount of pulverized coal recovered by this electrostatic precipitator, etc. is about 0.4 to 0.6% of the preheated drying amount. It cannot be charged into a coke oven as it is because it will disturb the operation of the coke oven, such as by scattering and being entrained in the generated gas or depositing as carbon on the walls of the coke oven. The method for treating the recovered pulverized coal during preheating drying is to mix the pulverized coal of 100 microns or less recovered in the coal preheating treatment process with liquid additives such as tar and heavy oil, and reduce the viscosity of the mixture to 100 centipoise or less. A method for treating pulverized coal in a coke oven that charges preheated coal (Japanese Unexamined Patent Application Publication No. 1983-1999 −134703) and other proposals have been made. The present invention uses dry pulverized coal, which is captured and recovered by an electrostatic precipitator in the coal preheating and drying process, to have a moisture content of 8 to 80%.
During preheating and drying of coking coal, which is characterized by mixing it with 10% wet coal, adjusting the moisture content of the mixed coal to 5% or more, adding it to molded raw coal, and molding it under pressure to make molded coal. This is a method for processing recovered pulverized coal. The pulverized coal captured and collected by the electrostatic precipitator has a moisture content of 8 to 10
% of wet coal to adjust the moisture content to 5 to 10% to prevent dust generation during transportation, and by adding it to molded coking coal and kneading it and pressurizing it to make molded coal. This prevents pulverized coal from being re-splattered during charging into the coke oven, and there is no possibility of pulverized coal being entrained in the generated gas or attached to the coke oven wall as carbon. In addition, the moisture content of mixed coal, which is made by mixing dry pulverized coal captured and collected by an electrostatic precipitator with wet coal, is 5%.
The reason for this is that if the moisture content of the mixed coal is less than 5%, it will not only generate dust at transfer points during transportation, but also generate dust when added to the molded coking coal, so it is necessary to have a moisture content of 5% or more. In addition, the moisture content of wet coal, which is the raw material for humidity control, is 8~
10%, so the moisture content of the mixed coal will not exceed 10%. In addition, mixing pulverized coal with wet coal and mixing it with molded coking coal is not possible when adding it to molded coking coal without mixing it with wet coal, as the recovered pulverized coal is extremely fine particles, so it may cause dust generation. This is because it is difficult to handle. Furthermore, the molded coking coal that is mixed with the above mixed coal is not limited to wet coal, but even dry preheated coal, when viewed in terms of quantity, the mixed coal accounts for about 5% of the molded coking coal, and does not have any adverse effects. Never. Example 1 Pulverized coal of 150 microns or less (moisture 0%) captured and recovered by an electrostatic precipitator after the cyclone in the coal preheating treatment process using a fluidized bed furnace and wet coal with a moisture content of 8% were mixed to reduce the moisture content to 3 to 6. % of mixed coal was adjusted, each mixed coal was conveyed by a belt conveyor, and the state of dust generation at the transfer section, that is, the chute section of the conveyor was visually observed. The results are shown in Table 1.
【表】
第１表に示すとおり混合炭の水分が５％以上の
場合には、シユート部における発塵は全くなく、
湿炭と同様に取扱えることがわかる。
実施例 ２
実施例１と同じ粒度が150ミクロン以下の微粉
炭37.5部と水分８％の湿炭62.5部を混合して水分
５％の混合炭を調整し、該混合炭を成型原料炭に
５〜15％配合し、バインダーとしてコールタール
の300℃以下の留分をカツトしたロードタールを
添加して混練した後、ダブルロール成型機を用い
て加圧成型し、35mm×35mm×25mmのマセツク型成
型炭となし、各成型炭Ａ〜Ｃを予熱処理した配合
炭に30％混合した装入炭Ｘ〜Ｚを1/4屯試験炉に
装入し、1100℃で20時間乾留してコークス化し
た。
第２表に混合炭、成型原料炭および配合炭の性
状を、第３表に各成型炭の性状を、第４表に1/4
屯試験炉へ装入時の装入炭Ｘ〜Ｚ中の回収微粉炭
量および生成コークスのドラム強度を示す。
なお、第２〜４表中における工業分析はJIS
M8812、CSNはJIS M8801−５、成型炭水分は
JIS M8811−６、コークス強度はJIS Ｋ−2151−
６に準じて測定し、成型炭のシ[Table] As shown in Table 1, when the moisture content of the mixed coal is 5% or more, there is no dust generation at the chute section.
It can be seen that it can be handled in the same way as wet coal. Example 2 A mixed coal with a moisture content of 5% was prepared by mixing 37.5 parts of pulverized coal with a particle size of 150 microns or less, which is the same as in Example 1, and 62.5 parts of wet coal with a moisture content of 8%. ~15%, and after kneading with the addition of road tar, which is a cut of the fraction of coal tar below 300°C, as a binder, it is pressure molded using a double roll molding machine to form a 35mm x 35mm x 25mm machete mold. Charging coal X to Z, which is a 30% mixture of each of the briquettes A to C and a preheated coal blend, are charged into a 1/4 ton test furnace and carbonized at 1100°C for 20 hours to form coke. did. Table 2 shows the properties of mixed coal, molten coking coal, and blended coal, Table 3 shows the properties of each briquette, and Table 4 shows 1/4
The amount of recovered pulverized coal in the charged coals X to Z and the drum strength of the produced coke at the time of charging into the Tun test furnace are shown. In addition, the industrial analysis in Tables 2 to 4 is based on JIS
M8812, CSN is JIS M8801-5, molded coal moisture is
JIS M8811-6, coke strength is JIS K-2151-
Measure according to 6.
【表】【table】
【表】【table】
【表】
ヤツター強度は、JISK2151のコークスの落下強
度試験法の装置を使用し、完全な形状の５Kgの成
型炭を２ｍの高さから鉄板上に４回落下させ、15
mmの篩で篩分した＋15mmの百分率で示す。
第３、４表に示すとおり、150ミクロン以下の
微粉炭37.5％を含む混合炭を成型原料炭に添加混
合した場合、混合炭の配合割合の上昇につれて成
型炭のシヤツター強度は若干低下するが、配合炭
に成型炭を添加したコークス炉へ装入し、乾留し
て得たコークスのドラム強度は、ほとんど差がな
かつた。
また、装入炭中に含める150ミクロン以下の回
収微粉炭量の0.6〜1.7％は、装入炭中の70％を占
める予熱配合炭の0.86〜2.4％に相当し、予熱処
理時の回収率0.4〜0.6％を上廻つており、回収微
粉炭の全量を成型炭中へ混入処理できることがわ
かる。
以上述べたとおり本発明を以つてすれば、従来
処置に困つていた石炭の予熱乾燥処理工程の電気
集塵機で捕捉回収される微粉炭を、先ず湿炭と混
合して混合炭の水分を５％以上に調整することに
よつて搬送時を発塵を防止し、かつ、該混合炭を
成型原料炭に添加して加圧成型し、成型炭とする
ことによつてコークス炉へ装入時の再飛散が完全
に防止でき、しかも、生成コークス強度を低下さ
せることもない等多くの利点を有する。[Table] Yatsuter strength is determined by dropping perfectly shaped 5 kg briquette coal four times from a height of 2 m onto an iron plate using a JIS K2151 coke drop strength test method.
It is expressed as a percentage of +15 mm sieved with a mm sieve. As shown in Tables 3 and 4, when mixed coal containing 37.5% of pulverized coal of 150 microns or less is added to molten coking coal, the shatter strength of the molten coal decreases slightly as the blending ratio of mixed coal increases; There was almost no difference in the drum strength of the coke obtained by charging into a coke oven with briquette coal added and carbonizing it. In addition, 0.6 to 1.7% of the recovered pulverized coal of 150 microns or less included in the charged coal is equivalent to 0.86 to 2.4% of the preheated blended coal, which accounts for 70% of the charged coal, and the recovery rate during preheating treatment is It is over 0.4 to 0.6%, indicating that the entire amount of recovered pulverized coal can be mixed into briquette coal. As described above, with the present invention, the pulverized coal captured and recovered by the electrostatic precipitator in the preheating and drying process of coal, which has been difficult to treat in the past, is first mixed with wet coal to reduce the water content of the mixed coal by 50%. % or more to prevent dust generation during transportation, and by adding the mixed coal to molded coking coal and molding it under pressure to form molded coal, when charging into a coke oven. It has many advantages, such as being able to completely prevent re-entrainment of coke and not reducing the strength of the produced coke.