JP3702972B2

JP3702972B2 - Steelmaking aids

Info

Publication number: JP3702972B2
Application number: JP09586895A
Authority: JP
Inventors: 巧田中; 征一郎栗山; 春樹大前
Original assignee: Nisshin Steel Co Ltd
Current assignee: Nippon Steel Nisshin Co Ltd
Priority date: 1995-03-30
Filing date: 1995-03-30
Publication date: 2005-10-05
Anticipated expiration: 2020-10-05
Also published as: JPH08269520A

Description

【０００１】
【産業上の利用分野】
本発明は、溶銑および溶鋼容器内のスラグのフォ−ミングを鎮静させる製鋼用補助材料に関するものである。
【０００２】
【従来の技術】
転炉の出鋼が終了すると炉内の残留しているスラグを専用の容器に受けるが、このとき溶融スラグ中には多量のガスを包含していためスラグが膨脹して容器から溢れでる。これを防ぐために、白樫、ナラ、クヌギ等を伐採し直径約５０ｍｍで長さ３００ｍｍ程度に加工した丸太を適宜投入して、この丸太の燃焼でスラグ中のガスを抜いて沈静化を図っている。
また、高炉から出銑した溶銑においても溶銑樋や取鍋、又はトピ−ドカ−にて予備処理剤を投入添加して、溶銑脱硫、脱燐を施しているがこの際にもスラグのフォ−ミングが起こり、脱硫・脱燐処理を中断して前記した丸太を投入して抑制を行っている。
【０００３】
【発明が解決しようとする課題】
しかし、最近の労働事情や森林保全のために伐採量が少なくなり、製鋼補助材としての丸太の供給量及び価格も高騰し、安定した供給に支障を来す傾向となっている。
この丸太の代替材料として木材チップを加工したオガライトが採用され始めたが、製鋼用の補助材として満足できるものではなかった。
【０００４】
すなわち、従来のオガライトでは、密度が小さくしかも長さが５０ｍｍ程度の短いものであったために、落下の衝撃力のみでは大気に晒されて粘性の低下したスラグ表面を破壊せずに、スラグ表面で燃焼しているのでスラグ中のガス抜きには十分に作用しなかった。また発熱量も小さくガス抜きに十分でなかった。
【０００５】
そこで、本発明は前記オガライトの欠点を解消して好適な製鋼用補助材料を提供することを目的とするものである。
【０００６】
【課題を解決するための手段】
本発明の製鋼用補助材は、木材チップ或いはオガ屑９０（重量）％以上に熱可塑性樹脂を１０（重量）％以下配合した後に、加圧成型機にて成型してなるもので、最大粒径が３ｍｍ以下の木材チップ或いはオガ屑を加熱した後に、熱可塑性樹脂を添加混合することを特徴とする。さらに、前記加熱温度が７５℃以下で、添加する熱可塑性樹脂は融点が７５℃以上で形状が３ｍｍ以下の粒状あるいは薄片であり、得られた補助材は中空状の棒体で外径が４０〜６０ｍｍ、長さが２５０〜３５０ｍｍである。
【０００７】
【作用】
粒径３ｍｍ以下に粗砕した木材チップを７５℃以下の温度にて予め加熱を施し、木材チップに熱が付与されると、この木材チップに熱可塑性樹脂を供給する。混合時に温度が７５℃を越えると熱可塑性樹脂が軟化溶融に近い状態となり、混合するときに均一な混合物が得られないかまたは均一な混合物を得るために長時間の混合が必要となる。また常温付近の加熱においては、加圧成型時の発熱量では温度不足を来し熱可塑性樹脂が軟化溶融してチップ間の間隙を埋め合わせ、接着効果を増し、更に密度の増加に寄与しないため、木材チップの加熱温度の範囲は好適には５５〜７５℃が望ましい。
【０００８】
添加する熱可塑性樹脂の形状は、充填性を向上させるために粒径３ｍｍ以下の粒状あるいは薄片としている。また、本発明の補助材は中空状の棒体で外径が４０〜６０ｍｍ、長さが２５０〜３５０ｍｍとしているため、補助材がスラグに突き刺さり中空部が煙突効果を発揮しスラグ中のガスが容易に大気中に飛散するとともに、作業者が容易に掴んで投げ込む事ができ、取扱が至便となる。
【０００９】
熱可塑性樹脂の混合割合が１０（重量）％を越えると、密度及び発熱量は上昇して使用時のフォーミングを抑制する効果は期待できるが、成型時に軟化が大きく、更に添加量が増すごとに爆裂的な燃焼を伴うので取扱上支障を来し、生産効率の面から上限を１０（重量）％と規定した。なお、好適な配合としては、３〜６（重量）％である。
【００１０】
【実施例】
以下、本発明の実施例を説明する。
木材チップを３ｍｍ以下に粗砕きした素材を貯蔵してコンベアで必要量切り出し木材チップを７０℃に加熱してポリエチレン（ＰＥ）を混合して外径５０ｍｍの太さで中に直径１３ｍｍの中空を有する棒状に連続加圧成型を行い長さ３００ｍｍに切断した。
加圧成型して得た補助材料の物性を表１に示す。また従来品である丸太及びオガライトの物性を表２に示す。
７０℃に加熱した木材チップに粒径３ｍｍ以下のポリエチレンを表１に示す割合でそれぞれ添加して材料をスクリュ−コンベアにて加圧成型機に送り込み４０〜４５ｋｇ／ｃｍ２に加圧して成型品を得た。なお、ポリエチレンの最大粒径を３ｍｍ以下に限定したのは、充填性を向上するためであって、ポリエチレンシ−トを廃棄したものを切断したものであっても構わない。
【００１１】
前記条件にて製造すると摩擦熱が生じ添加したポリエチレンが軟化して、隙間に入り込むと同時に接着効果を生じ従来品である木材チップのみより発熱量、密度共に高くなりスラグの表面に生成した固い皮を破りスラグの溶融部に補助材が突き刺さり内部にあるガスを放散してフォーミングを沈静化させた。また、本補助材に添加したポリエチレンが１４００〜１６００℃の高温に晒されると火烈な燃焼を伴うので溶融スラグ中に包含するガスを放散させる。本実施例ではポリエチレンを用いたが、熱可塑性樹脂の融点が７５℃以上であればポリプロピレン、酢酸ビニールを配合しても構わない。
【００１２】
【表１】
【００１３】
【表２】
なお、木材チップのみの実施例を挙げたがオガ屑も木材を製材して得られたものであって、発熱量は基本的に変わらないので敢えて記載しなかったが木材チップと同様な作用及び効果を得る。
【００１４】
【発明の効果】
木材チップ或いはオガ屑に熱可塑性樹脂を１０（重量）％以下配合した後に、加圧成型機にて成型してなる製鋼用補助材であるから、高い発熱量と高い密度のものが得られ、スラグの表面を容易に破壊して本材が侵入して激しく燃焼するのでスラグ中に包含するガスを放散して、フォーミングを素早く抑制し、補助材の使用量も従来に比べて少なくて済む。
【００１５】
最大粒径が３ｍｍ以下の木材チップ或いはオガ屑を加熱した後に、熱可塑性樹脂を添加配合することにより更なる密度の向上が期待できる。
【００１６】
前記加熱温度が７５℃以下で木材チップ或いはオガ屑を加熱した後に熱可塑性樹脂を配合するので、熱可塑性樹脂が軟化溶融状態を呈しないので均一に混合が行われる。
【００１７】
補助材は中空状の棒体で外径が４０〜６０ｍｍ、長さが２５０〜３５０ｍｍであるから、補助材がスラグ突き刺さり中空部が煙突効果を発揮しスラグ中のガスが容易に大気中に飛散することができるとともに、作業員が容易に掴んで投げ込む事ができ、取扱が至便である。[0001]
[Industrial application fields]
The present invention relates to an auxiliary material for steel making that calms the forming of hot metal and slag in a molten steel container.
[0002]
[Prior art]
When the steelmaking of the converter is completed, the slag remaining in the furnace is received in a dedicated container. At this time, since the molten slag contains a large amount of gas, the slag expands and overflows from the container. In order to prevent this, logs made by cutting white birch, oak, kunugi, etc., and processing them to a length of about 300 mm with a diameter of about 50 mm are appropriately added, and by burning the logs, the gas in the slag is extracted to calm down. .
In addition, hot metal discharged from the blast furnace is subjected to hot metal desulfurization and dephosphorization by adding a pretreatment agent with hot metal, a ladle or a top-decker. In the process, desulfurization / dephosphorization processing is interrupted and the above-mentioned log is introduced to suppress the dehumidification.
[0003]
[Problems to be solved by the invention]
However, due to recent labor conditions and forest conservation, the amount of logging has decreased, and the supply amount and price of logs as steelmaking auxiliary materials have also risen, which tends to hinder stable supply.
Ogarite with processed wood chips began to be used as an alternative material for this log, but it was not satisfactory as an auxiliary material for steelmaking.
[0004]
In other words, the conventional ogarite has a small density and a short length of about 50 mm, so that only the impact force of the drop does not destroy the slag surface that has been exposed to the atmosphere and has reduced its viscosity. Since it was burning, it did not work well for degassing the slag. Moreover, the calorific value was small and it was not sufficient for degassing.
[0005]
Then, this invention aims at eliminating the fault of the said ogarite and providing the auxiliary material for steelmaking suitable.
[0006]
[Means for Solving the Problems]
The steelmaking auxiliary material of the present invention is obtained by blending 10% (wt) or less of a thermoplastic resin into 90% (wt)% or more of wood chips or sawdust, and then molding it with a pressure molding machine. A thermoplastic resin is added and mixed after heating wood chips or sawdust having a diameter of 3 mm or less. Further, the thermoplastic resin to be added is a granular or flake having a melting point of 75 ° C. or more and a shape of 3 mm or less, and the obtained auxiliary material is a hollow rod having an outer diameter of 40 ° C. -60 mm and length is 250-350 mm.
[0007]
[Action]
When wood chips crushed to a particle size of 3 mm or less are preliminarily heated at a temperature of 75 ° C. or less and heat is applied to the wood chips, a thermoplastic resin is supplied to the wood chips. When the temperature exceeds 75 ° C. during mixing, the thermoplastic resin is in a state close to softening and melting, and when mixing, a uniform mixture cannot be obtained or long time mixing is required to obtain a uniform mixture. In addition, in heating near normal temperature, the calorific value at the time of pressure molding comes to a temperature shortage and the thermoplastic resin softens and melts, filling the gap between chips, increasing the adhesion effect, and further does not contribute to the increase in density, The range of the heating temperature of the wood chip is preferably 55 to 75 ° C.
[0008]
The shape of the thermoplastic resin to be added is granular or flakes having a particle size of 3 mm or less in order to improve the filling property. In addition, since the auxiliary material of the present invention is a hollow rod having an outer diameter of 40 to 60 mm and a length of 250 to 350 mm, the auxiliary material pierces the slag and the hollow portion exhibits a chimney effect, and the gas in the slag is It easily scatters into the atmosphere and can be easily grasped and thrown by the operator, making it easy to handle.
[0009]
When the mixing ratio of the thermoplastic resin exceeds 10% (weight), the density and heat generation amount can be increased, and the effect of suppressing the forming during use can be expected. Explosive combustion is involved, which hinders handling, and the upper limit is defined as 10 (weight)% in terms of production efficiency. In addition, as a suitable mixing | blending, it is 3-6 (weight)%.
[0010]
【Example】
Examples of the present invention will be described below.
A material obtained by roughly crushing wood chips to 3 mm or less is stored, and a necessary amount is cut out by a conveyor. The wood chips are heated to 70 ° C. and mixed with polyethylene (PE) to form a hollow having a diameter of 50 mm and a diameter of 13 mm inside. Continuous pressure molding was carried out into a rod shape having a length of 300 mm.
Table 1 shows the physical properties of the auxiliary material obtained by pressure molding. Table 2 shows the physical properties of conventional logs and ogarite.
Polyethylene having a particle size of 3 mm or less is added to wood chips heated to 70 ° C. in the proportions shown in Table 1, and the material is fed into a pressure molding machine by a screw conveyor and pressurized to 40 to 45 kg / cm 2 to obtain a molded product. Obtained. The reason why the maximum particle size of polyethylene is limited to 3 mm or less is to improve the filling property, and the polyethylene sheet may be cut and discarded.
[0011]
When manufactured under the above conditions, frictional heat is generated, and the added polyethylene softens and enters the gap. At the same time, the adhesive effect is produced, and both the calorific value and density are higher than the conventional wood chip alone, and the hard skin formed on the surface of the slag The auxiliary material pierced into the molten part of the slag and diffused the gas in the interior to calm the forming. Further, when the polyethylene added to the auxiliary material is exposed to a high temperature of 1400 to 1600 ° C., it is accompanied by intense combustion, so that the gas included in the molten slag is diffused. In this embodiment, polyethylene is used, but polypropylene and vinyl acetate may be blended as long as the melting point of the thermoplastic resin is 75 ° C. or higher.
[0012]
[Table 1]
[0013]
[Table 2]
In addition, although the example only of wood chip was given, sawdust was also obtained by sawing wood, and the calorific value was basically unchanged, so it was not described darely, but the same action as wood chip and Get the effect.
[0014]
【The invention's effect】
Since it is an auxiliary material for steel making that is formed by a pressure molding machine after blending 10% (wt) or less of a thermoplastic resin with wood chips or sawdust, a high calorific value and high density are obtained, Since the surface of the slag is easily destroyed and this material enters and burns violently, the gas contained in the slag is diffused, forming is quickly suppressed, and the amount of auxiliary material used is less than in the prior art.
[0015]
Further improvement in density can be expected by adding and blending a thermoplastic resin after heating wood chips or sawdust having a maximum particle size of 3 mm or less.
[0016]
Since the thermoplastic resin is blended after heating the wood chips or sawdust at the heating temperature of 75 ° C. or less, the thermoplastic resin does not exhibit a softened and melted state, and thus mixing is performed uniformly.
[0017]
Since the auxiliary material is a hollow rod with an outer diameter of 40-60 mm and a length of 250-350 mm, the auxiliary material pierces the slag and the hollow part exhibits a chimney effect, and the gas in the slag is easily scattered into the atmosphere. In addition, the operator can easily grab and throw it in, and the handling is convenient.

Claims

A steelmaking auxiliary material obtained by blending 90 (wt)% or more of wood chips or sawdust and 10 (wt)% or less of a thermoplastic resin and then molding the mixture with a pressure molding machine.

The auxiliary material for steelmaking according to claim 1, wherein a thermoplastic resin is added and mixed after heating wood chips or sawdust having a maximum particle size of 3 mm or less.

The auxiliary material for steel making according to claim 2, wherein the heating temperature is 75 ° C or lower.

The auxiliary material for steel making according to any one of claims 1 to 3, wherein the thermoplastic resin is a granular or flake having a melting point of 75 ° C or higher and a shape of 3mm or less.

The auxiliary material for steel making according to any one of claims 1 to 4, wherein the auxiliary material is a hollow rod having an outer diameter of 40 to 60 mm and a length of 250 to 350 mm.