JP2023132282A - Converter heating material and method for producing the same - Google Patents

Converter heating material and method for producing the same Download PDF

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JP2023132282A
JP2023132282A JP2022037508A JP2022037508A JP2023132282A JP 2023132282 A JP2023132282 A JP 2023132282A JP 2022037508 A JP2022037508 A JP 2022037508A JP 2022037508 A JP2022037508 A JP 2022037508A JP 2023132282 A JP2023132282 A JP 2023132282A
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carbide
particle size
converter
molded body
heat
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淳史 湯本
Atsushi Yumoto
利一 青木
Riichi Aoki
政洋 関屋
Masahiro Sekiya
哲哉 加藤
Tetsuya Kato
宗幸 鎌田
Muneyuki Kamata
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Nippon Steel Corp
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Abstract

To provide a converter heating material capable of reducing the addition amount of a binder while increasing the strength of the heating material by increasing the filling rate of a carbide, and a method for producing the same.SOLUTION: A converter heating material of a carbide molded body obtained by being molded with a carbide particulate body and a binder. A carbide in the carbide molded body has (a) a particle diameter in which the maximum particle diameter is below 1/2 of the typical length d of the carbide molded body, and (b) when it is classified so that a large particle diameter side reaches 70 vol.% and a small particle diameter side reaches 30 vol.%, a ratio between the median particle diameter D50 of the carbide on the large particle diameter side and the median particle diameter D50 of the carbide on the small particle diameter side is 1.5 to 2.3. Also provided is a method for producing a converter heating material in which a carbide raw material is subjected to one or plural screening treatments and one or plural breaking treatments so that the carbide particulate body has particulate size distributions similar to the (a) and (b).SELECTED DRAWING: Figure 7

Description

本発明は、転炉用昇熱材に関し、詳しくは、昇熱材の原料である炭化物の充填率を高めて昇熱材の強度を高めつつバインダーの添加量を適正化する転炉用昇熱材およびその製造方法に関する。 The present invention relates to a heating material for a converter, and more particularly, the present invention relates to a heating material for a converter, which increases the filling rate of carbide, which is a raw material for the heating material, and increases the strength of the heating material, while optimizing the amount of binder added. Materials and methods of manufacturing them.

製鋼工程の転炉は、高炉で出銑された溶銑に高純度の酸素を高速で吹き付けることにより脱炭を行い、溶鋼を製造する主要なプロセスである。同時に、生石灰を主体とする副原料を投入し、溶銑中の不純物(リン等)の除去を行う。 A converter in the steelmaking process is a major process in which hot metal tapped in a blast furnace is decarburized by spraying high-purity oxygen at high speed to produce molten steel. At the same time, auxiliary raw materials mainly consisting of quicklime are added to remove impurities (such as phosphorus) from the hot metal.

一方、転炉の前工程として溶銑予備処理を行い、鉄鋼製品の材料特性面の要求から溶銑中のS、Pなどを除く処理を行う場合もある。この場合、溶銑予備処理により溶銑温度が低下するという問題がある。 On the other hand, hot metal pretreatment is sometimes performed as a pre-process of the converter to remove S, P, etc. from the hot metal due to material property requirements for steel products. In this case, there is a problem that the hot metal temperature decreases due to the hot metal pretreatment.

また近年、環境保護の観点から、製鉄プロセスにおいてはCO排出量の削減が重要課題となっており、製鋼工程においては、使用する鉄源として鉄スクラップ(屑鉄)などの冷鉄源の配合比率を高め、溶銑の配合比率を低減することが試みられている。これは、鉄鋼製品の製造にあたり、高炉での溶銑の製造では、鉄鉱石を還元し且つ溶融するための多大なエネルギーを要すると同時に多量のCOを排出するのに対し、冷鉄源は溶解熱のみを必要としており、製鋼工程で冷鉄源を利用した場合には、鉄鉱石の還元熱分のエネルギー使用量を少なくすることができ、CO発生量を大幅に削減することができるからである。しかしながら、転炉においては、冷鉄源の溶解用熱源は溶銑の有する顕熱、及び溶銑中の炭素及び珪素の酸化熱であり、冷鉄源の溶解量には自ずと限界がある。 In addition, in recent years, from the perspective of environmental protection, reducing CO2 emissions has become an important issue in the steelmaking process, and in the steelmaking process, the proportion of cold iron sources such as iron scrap (scrap iron) has been increased Attempts have been made to increase the ratio of hot metal and reduce the blending ratio of hot metal. This is because the production of hot metal in a blast furnace requires a large amount of energy to reduce and melt the iron ore and at the same time emits a large amount of CO 2 in the production of steel products, whereas cold iron sources produce molten metal. Only heat is required, and if a cold iron source is used in the steelmaking process, the amount of energy used for the reduction heat of iron ore can be reduced, and CO2 emissions can be significantly reduced. It is. However, in a converter, the heat source for melting the cold iron source is the sensible heat of the hot metal and the oxidation heat of carbon and silicon in the hot metal, and there is naturally a limit to the amount of cold iron source melted.

そこで、溶銑の脱燐処理や脱炭精錬において、溶銑の熱的余裕を高めて冷鉄源の配合比率を拡大するべく、溶銑に追加の炭素源を供給する昇熱材として、石炭、コークス粉、黒鉛、電極粉、SiCなどを塊状に成型した昇熱材が種々提案されている。なお、成型しない天然鉱産物の土状黒鉛も、比較的安価であることから、昇熱材として用いられる場合もある。 Therefore, in the dephosphorization treatment and decarburization refining of hot metal, in order to increase the thermal margin of hot metal and expand the blending ratio of cold iron sources, coal and coke powder are used as heating materials to supply an additional carbon source to hot metal. , graphite, electrode powder, SiC, etc., have been proposed in a variety of heat raising materials formed into lumps. Note that earthy graphite, which is a natural mineral product that is not molded, is also sometimes used as a heating material because it is relatively inexpensive.

そのような転炉用の昇熱材については、たとえば、特許文献1では、粒度が1mm以下を30~70%含み、他は粒度が1~8mmの炭素粉(石炭、コークス粉、黒鉛など)に、炭素粉の0.5~1.0重量%の範囲でポリビニルアルコール、カルボキシメチルセルロース、α澱粉などからなるバインダーを加え、含有水分が10%以下となるように調質して混錬後、高圧成形、乾燥することにより、炭素粉を十分な強度の固形物に成型することを可能としている。 Regarding such heat raising materials for converters, for example, in Patent Document 1, carbon powder (coal, coke powder, graphite, etc.) containing 30 to 70% particles with a particle size of 1 mm or less, and the rest with a particle size of 1 to 8 mm is used. Add a binder consisting of polyvinyl alcohol, carboxymethyl cellulose, alpha starch, etc. in the range of 0.5 to 1.0% by weight of the carbon powder, temper and knead so that the water content is 10% or less, By high-pressure molding and drying, it is possible to mold carbon powder into a solid material with sufficient strength.

また、特許文献2では、カーボンニュートラルな植物系バイオマスを炭化した炭化物と、炭化物の質量に対して1~15質量%の澱粉、カルボキシメチルセルロース、コーンスターチなどからなるバインダーとで成型してなる転炉用昇熱材を、石炭、コークス、黒鉛等の化石資源を原料とする従来からの転炉用昇熱材の代替とすることにより、化石資源消費量を低減し、温室効果ガスであるCOの発生を低減できるようにするととともに、炭化物の粒径を3mm以下とすることにより、転炉用昇熱材として十分な強度である圧潰強度490N/個以上の固形物にしている。 Furthermore, in Patent Document 2, a converter molded with a charred material obtained by carbonizing carbon-neutral plant biomass and a binder made of starch, carboxymethyl cellulose, corn starch, etc. in an amount of 1 to 15% by mass based on the mass of the charred material. By using the heating material as an alternative to conventional heating materials for converters that are made from fossil resources such as coal, coke, and graphite, fossil resource consumption can be reduced and CO2 , which is a greenhouse gas, can be reduced. By making it possible to reduce the generation of carbides and making the particle size of the carbide 3 mm or less, the solid material has a crushing strength of 490 N/piece or more, which is sufficient strength as a heat raising material for a converter.

特開平2-270922号公報Japanese Patent Application Publication No. 2-270922 特許第5846289号公報Patent No. 5846289

しかしながら、特許文献1に記載された昇熱材の原料の炭素粉は、粒度が1mm以下のものの割合が30~70%と多いため、そのための炭素原料の粉砕処理等、粒度調整のための処理負荷が高いという問題がある。 However, since the carbon powder used as the raw material for the heating material described in Patent Document 1 has a large proportion of particles with a particle size of 1 mm or less at 30 to 70%, treatments for particle size adjustment such as pulverization of the carbon raw material are necessary. The problem is that the load is high.

また、特許文献2に記載された昇熱材の原料の炭素粉は、粒径3mm以下と比較的狭い粒度範囲に整粒する必要があり、特許文献1に記載された発明同様に、そのための炭素原料の粉砕処理等、粒度調整のための処理負荷が高いという問題がある。 Furthermore, the carbon powder used as the raw material for the heating material described in Patent Document 2 needs to be sized to a relatively narrow particle size range of 3 mm or less, and similar to the invention described in Patent Document 1, the There is a problem in that the processing load for particle size adjustment, such as pulverization of carbon raw materials, is high.

また、特許文献1に記載された昇熱材では、炭素粉の0.5~1.0重量%の範囲でバインダーが使用され、特許文献2に記載された昇熱材では、炭化物の1~15質量%のバインダーが使用されているところ、近年、植物由来のバインダーの、具体的にはトウモロコシ由来のコーンスターチの価格変動が大きくなっていることが問題となっている。これは、異常気象によるトウモロコシの作柄不良に連動した価格変動や、環境負荷低減のためのトウモロコシ由来のバイオエタノールの需要増に伴う価格上昇圧力のためである。そのため、昇熱材の成型時に使用するバインダーを低減させる技術が従来に増して求められるようになってきている。 Furthermore, in the heating material described in Patent Document 1, a binder is used in a range of 0.5 to 1.0% by weight of carbon powder, and in the heating material described in Patent Document 2, a binder is used in a range of 1 to 1.0% by weight of carbon powder. Although 15% by mass of binder is used, in recent years, a problem has been that the price fluctuations of plant-derived binders, specifically corn starch derived from corn, have increased. This is due to price fluctuations linked to poor corn crops due to abnormal weather, and upward pressure on prices due to increased demand for corn-derived bioethanol to reduce environmental impact. Therefore, there is an increasing demand for technology that reduces the amount of binder used when molding heat-raising materials.

一方で、バインダーの添加量が必要量よりも過少であると、成型した炭材の強度不足等の異常が生じ、搬送時の操業トラブルや歩留まり低下等の問題が発生する。また、バインダー量の削減による成型炭材の強度不足の問題を、原料の炭化物を全て微破砕することで成型炭材の強度を確保して解消することとすれば、炭化物の微破砕のためのコスト増の問題が生じて総合的な経済性が損なわれるという問題がある。 On the other hand, if the amount of binder added is less than the required amount, abnormalities such as insufficient strength of the molded carbon material will occur, leading to problems such as operational troubles during transportation and a decrease in yield. In addition, if the problem of insufficient strength of the molded carbonaceous material due to the reduction of the amount of binder is solved by ensuring the strength of the molded carbonaceous material by finely crushing all the raw material carbide, then There is a problem in that the problem of increased costs arises and the overall economic efficiency is impaired.

本発明は、上記のような事情に鑑みてなされたものであり、昇熱材の原料である炭化物の粒度の分布を適正化することにより、炭化物の充填率を高めて昇熱材の強度を高めつつバインダーの添加量を削減することを可能とする転炉用昇熱材およびその製造方法を提供することを目的とするものである。 The present invention has been made in view of the above circumstances, and by optimizing the particle size distribution of carbide, which is a raw material for heating material, it is possible to increase the filling rate of carbide and increase the strength of heating material. The object of the present invention is to provide a heat raising material for a converter, which makes it possible to reduce the amount of binder added while increasing the amount of binder added, and a method for manufacturing the same.

[1]炭化物粉粒体とバインダーとで成型してなる炭化物成型体の転炉用昇熱材であって、前記炭化物成型体中の炭化物は、(a)最大粒径が前記炭化物成型体の代表長さdの1/2未満の粒径を有するものであり、(b)大粒径側が70体積%、小粒径側が30体積%となるように区分したときの、大粒径側の炭化物のメジアン粒径D50と小粒径側の炭化物のメジアン粒径D50の比が、1.5~2.3であることを特徴とする、転炉用昇熱材。
[2]前記転炉用昇熱材は、圧潰強度が490N/個以上であることを特徴とする、[1]に記載の転炉用昇熱材。
[3]炭化物粉粒体とバインダーとで成型してなる炭化物成型体の転炉用昇熱材の製造方法であって、石炭、植物系バイオマス、廃プラスチックの群から選択される少なくとも1つを炭化して炭化物原料を製造し、前記炭化物原料に対し、1または複数の篩分け処理および1または複数の破砕処理を施して、(a’)前記炭化物原料から、最大粒径が前記炭化物成型体の代表長さdの1/2未満となる範囲内で、粒度の異なる複数の群に区分けされた前記炭化物粉粒体を得るようにし、さらに、(b’)得られた前記炭化物粉粒体を、大粒径側が70体積%、小粒径側が30体積%となるように区分したときの、大粒径側の炭化物のメジアン粒径D50と小粒径側の炭化物のメジアン粒径D50の比が、1.5~2.3の範囲となるように調合して前記成型前の前記炭化物粉粒体とすることを特徴とする、転炉用昇熱材の製造方法。
[4]前記転炉用昇熱材は、圧潰強度が490N/個以上であることを特徴とする、[3]に記載の転炉用昇熱材の製造方法。
[1] A heating material for converter of a carbide molded body formed by molding carbide powder and a binder, wherein the carbide in the carbide molded body has (a) a maximum particle size of the carbide molded body; It has a particle size less than 1/2 of the representative length d, and (b) the large particle size side when divided so that the large particle size side accounts for 70% by volume and the small particle size side accounts for 30% by volume. A heat raising material for a converter, characterized in that the ratio of the median particle size D50 of the carbide to the median particle size D50 of the carbide on the small particle size side is 1.5 to 2.3.
[2] The heat-raising material for a converter according to [1], wherein the heat-raising material for a converter has a crushing strength of 490 N/piece or more.
[3] A method for producing a heating material for a converter of a carbide molded body formed by molding a carbide powder and a binder, the method comprising at least one selected from the group of coal, vegetable biomass, and waste plastic. A carbide raw material is produced by carbonization, and the carbide raw material is subjected to one or more sieving treatments and one or more crushing treatments, so that (a') the carbide raw material has a maximum particle size of the carbide molded body. (b') the obtained carbide powder is obtained by dividing the carbide powder into a plurality of groups with different particle sizes within a range of less than 1/2 of the representative length d; is divided into 70 volume % on the large grain size side and 30 volume % on the small grain size side, and the median particle size D50 of the carbide on the large grain size side and the median grain size D50 of the carbide on the small grain size side. A method for producing a heat raising material for a converter, characterized in that the carbide powder before molding is prepared by blending so that the ratio is in the range of 1.5 to 2.3.
[4] The method for producing a heat-raising material for a converter according to [3], wherein the heat-raising material for a converter has a crushing strength of 490 N/piece or more.

本発明によれば、転炉用昇熱材(炭化物成型体)(以下、単に昇熱材ともいう。)中の炭化物の粒度の分布を、炭化物の最大粒径が転炉用昇熱材の代表長さdの1/2未満の粒径とし、かつ、炭化物粒子を、大粒径側が70体積%、小粒径側が30体積%となるように区分したときの、大粒径側の炭化物のメジアン粒径D50と小粒径側の炭化物のメジアン粒径D50の比が1.5~2.3の範囲とすることにより、炭化物の充填率を高めて昇熱材の強度を高めつつ、経済的合理性のある範囲でバインダーの添加量を削減することを可能とする転炉用昇熱材およびその製造方法を提供することができる。 According to the present invention, the particle size distribution of carbide in a heat-raising material for a converter (carbide molded body) (hereinafter also simply referred to as a heat-raising material) is determined such that the maximum particle size of the carbide is the same as that of the heat-raising material for a converter. Carbide on the large particle size side when the particle size is less than 1/2 of the representative length d and the carbide particles are divided so that the large particle size side accounts for 70% by volume and the small particle size side accounts for 30% by volume. By setting the ratio of the median particle size D50 of the carbide to the median particle size D50 of the carbide on the small particle size side to be in the range of 1.5 to 2.3, the filling rate of the carbide is increased and the strength of the heating material is increased. It is possible to provide a heat raising material for a converter and a method for producing the same, which makes it possible to reduce the amount of binder added within an economically reasonable range.

本発明の転炉用昇熱材が用いられる転炉設備の1例の概略断面図である。1 is a schematic cross-sectional view of an example of converter equipment in which the heat-raising material for converter of the present invention is used. 本発明に至る予備実験および実施例で用いたロールクラッシャー(カッターミル)により、バイオマス炭を粉砕する様子を概略断面図で示す図である。FIG. 2 is a schematic cross-sectional view showing how biomass charcoal is crushed by a roll crusher (cutter mill) used in preliminary experiments and examples leading up to the present invention. 本発明に至る予備実験および実施例で用いた双ロール式ブリケットマシンにより、バイオマス炭の粉砕物を圧縮成形する様子を概略断面図で示す図である。FIG. 2 is a schematic cross-sectional view showing how pulverized biomass charcoal is compression-molded using a twin-roll briquette machine used in preliminary experiments and examples leading up to the present invention. 本発明に至る予備実験および実施例で用いたペレット製造機(ペレタイザー)により、バイオマス炭の粉砕物を押し出し成形する様子を概略断面図で示す図である。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view showing how pulverized biomass charcoal is extruded and molded by a pelletizing machine (pelletizer) used in preliminary experiments and examples leading up to the present invention. 本発明に至る予備実験で得られた図であって、転炉用昇熱材中の炭化物の大粒径と小粒径の割合と転炉用昇熱材の炭化物成型体の空隙率の関係を、大粒径と小粒径の粒子径比で層別してまとめた図である。It is a diagram obtained in preliminary experiments leading to the present invention, showing the relationship between the ratio of large grain size to small grain size of carbide in a heat raising material for a converter and the porosity of a carbide molded body of a heat raising material for a converter. FIG. 2 is a diagram summarizing the results by stratifying them according to the particle size ratio of large particles to small particles. 本発明に至る予備実験で得られた図であって、転炉用昇熱材中の炭化物の大粒径と小粒径の粒子径比と転炉用昇熱材の炭化物成型体の最小空隙率の関係をまとめた図である。FIG. 2 is a diagram obtained in preliminary experiments leading to the present invention, showing the particle size ratio between large and small particles of carbide in a heat-raising material for a converter, and the minimum void of a carbide molded body of a heat-raising material for a converter. FIG. 2 is a diagram summarizing the relationship between rates. 本発明に至る予備実験で得られた図であって、炭化物成型体の代表長さdに対する大粒径側の炭化物のメジアン粒径D50の比と転炉用昇熱材の成型の際に必要なバインダー濃度との関係をまとめた図である。It is a diagram obtained in preliminary experiments leading to the present invention, showing the ratio of the median particle size D50 of carbide on the large particle size side to the representative length d of the carbide molded body, and the ratio required when forming a heat raising material for a converter. FIG. 3 is a diagram summarizing the relationship with binder concentration. 本発明のペレット形状の炭化物成型体の実施例で用いられたバイオマス炭材の粉砕物の粒度の測定結果を示す図である。It is a figure which shows the measurement result of the particle size of the crushed biomass carbon material used in the Example of the pellet-shaped carbide molded object of this invention. 本発明のブリケット形状の炭化物成型体の実施例で用いられたバイオマス炭材の粉砕物の粒度の測定結果を示す図である。It is a figure showing the measurement result of the particle size of the crushed biomass carbon material used in the example of the briquette-shaped carbide molded object of the present invention.

以下、本発明を具体的に説明する。先ず、本発明を適用する転炉設備を説明する。図1は、本発明の転炉用昇熱材を用いる転炉設備の1例の概略断面図である。 The present invention will be explained in detail below. First, converter equipment to which the present invention is applied will be explained. FIG. 1 is a schematic sectional view of an example of converter equipment using the heat raising material for converter of the present invention.

図1において、溶銑8を収容した転炉本体1の内部には、上方から上吹きランス2が挿入され、この上吹きランス2から酸素ガスが溶銑8に吹き付けられると同時に、転炉本体1の底部に配置した複数の底吹き羽口3から攪拌用底吹きガスが吹き込まれて溶銑8とスラグ9とが攪拌されながら、溶銑8の脱炭精錬が行われる。溶銑8の脱炭精錬によって炉内からCOガスを主体とする転炉排ガス10が発生する。 In FIG. 1, a top-blowing lance 2 is inserted from above into a converter body 1 containing hot metal 8, and at the same time oxygen gas is blown onto the hot metal 8 from the top-blowing lance 2. The hot metal 8 is decarburized and refined while the hot metal 8 and the slag 9 are stirred by blowing bottom blowing gas for stirring from a plurality of bottom blowing tuyeres 3 arranged at the bottom. By decarburizing the hot metal 8 and refining it, a converter exhaust gas 10 mainly consisting of CO gas is generated from inside the furnace.

転炉本体1の上方には煙道4が設置され、煙道4の後段には、一次集塵機(図示せず)、二次集塵機(図示せず)、誘引送風機(図示せず)が、この順に設置されている。このような転炉排ガス10の処理設備により、脱炭精錬によって転炉本体1の内部で発生する転炉排ガス10を、冷却して除塵し未燃焼のまま、誘引送風機(図示せず)の下流側のガスホルダー(図示せず)に回収されるようになっている。 A flue 4 is installed above the converter main body 1, and a primary dust collector (not shown), a secondary dust collector (not shown), and an induced fan (not shown) are installed downstream of the flue 4. They are installed in order. With such converter exhaust gas 10 processing equipment, the converter exhaust gas 10 generated inside the converter main body 1 due to decarburization and refining is cooled, dust removed, and left unburned downstream of an induced fan (not shown). It is designed to be collected in a side gas holder (not shown).

煙道4の転炉本体1の炉口との接続側は、スカート5と呼ばれており、上下移動が可能な構造となっており、排ガスを回収する場合には、スカート5と転炉本体1の炉口とは原則的には密着した状態になる。また、煙道4には、生石灰、焼成ドロマイト、鉄鉱石、ミルスケール、マンガン鉱石、昇熱材(コークス、土壌黒鉛などの炭材)及び合金鉄(Fe-Mn、Fe-Siなど)などの副原料を転炉本体1に投入添加するための、ホッパー6及び投入シュート7などからなる副原料投入装置が設置されている。副原料投入装置から炉内に投入される生石灰、焼成ドロマイト、鉄鉱石、ミルスケール、マンガン鉱石などによってスラグ9が形成される。 The side of the flue 4 that connects to the furnace mouth of the converter body 1 is called a skirt 5, and has a structure that can be moved up and down.When collecting exhaust gas, the skirt 5 and the converter body In principle, it will be in close contact with the furnace mouth of No. 1. In addition, the flue 4 contains materials such as quicklime, calcined dolomite, iron ore, mill scale, manganese ore, heating materials (carbon materials such as coke and soil graphite), and ferroalloys (Fe-Mn, Fe-Si, etc.). An auxiliary raw material charging device including a hopper 6, a charging chute 7, and the like is installed for adding auxiliary raw materials to the converter main body 1. Slag 9 is formed by quicklime, calcined dolomite, iron ore, mill scale, manganese ore, etc. that are input into the furnace from an auxiliary raw material input device.

本発明の転炉用昇熱材は、炭化物粉粒体とバインダーとで成型してなる炭化物成型体の転炉用昇熱材であって、前記炭化物成型体中の炭化物は、(a)最大粒径が前記炭化物成型体の代表長さdの1/2未満の粒径を有するものであり、(b)大粒径側が70体積%、小粒径側が30体積%となるように区分したときの、大粒径側の炭化物のメジアン粒径D50と小粒径側の炭化物のメジアン粒径D50の比が、1.5~2.3であることを特徴とする。 The heat-raising material for a converter of the present invention is a heat-raising material for a converter that is a carbide molded body formed by molding carbide powder and a binder, wherein the carbide in the carbide molded body is (a) maximum The particle size is less than 1/2 of the representative length d of the carbide molded body, and (b) the large particle size side is 70% by volume and the small particle size side is 30% by volume. The ratio of the median particle size D50 of the carbide on the large particle size side to the median particle size D50 of the carbide on the small particle size side is 1.5 to 2.3.

また、本発明の転炉用昇熱材の製造方法は、炭化物粉粒体とバインダーとで成型してなる炭化物成型体の転炉用昇熱材の製造方法であって、石炭、植物系バイオマス、廃プラスチックの群から選択される少なくとも1つを炭化して炭化物原料を製造し、前記炭化物原料に対し、1または複数の篩分け処理および1または複数の破砕処理を施して、(a’)前記炭化物原料から、最大粒径が前記炭化物成型体の代表長さdの1/2未満となる範囲内で、粒度の異なる複数の群に区分けされた前記炭化物粉粒体を得るようにし、さらに、(b’)得られた前記炭化物粉粒体を、大粒径側が70体積%、小粒径側が30体積%となるように区分したときの、大粒径側の炭化物のメジアン粒径D50と小粒径側の炭化物のメジアン粒径D50の比が、1.5~2.3の範囲となるように調合して前記成型前の前記炭化物粉粒体とすることを特徴とする。 Further, the method for producing a heat-raising material for a converter of the present invention is a method for producing a heat-raising material for a converter, which is a carbide molded body formed by molding a carbide powder and a binder, and comprises using coal, vegetable biomass, etc. , producing a carbide raw material by carbonizing at least one selected from the group of waste plastics, and subjecting the carbide raw material to one or more sieving treatments and one or more crushing treatments, (a') The carbide powder is obtained from the carbide raw material, and the carbide powder is divided into a plurality of groups having different particle sizes within a range where the maximum particle size is less than 1/2 of the representative length d of the carbide molded body, and , (b') When the obtained carbide powder is divided into 70% by volume on the large particle side and 30% by volume on the small particle side, the median particle size D50 of the carbide on the large particle size side and the median particle size D50 of the carbide on the small particle size side is in the range of 1.5 to 2.3 to obtain the carbide powder before molding.

本発明の炭化物成型体(転炉用昇熱材)は、炭化物粉粒体を主原料にしてバインダーと水を加え、公知のミキサー(図示せず)で混合、撹拌してから公知の成型装置(図3、図4参照)によって成型し、その後、所定の水分量まで乾燥させることにより得られる。主原料の炭化物粉粒体は、まず、原料である石炭、植物系バイオマス、廃プラスチック等を、ロータリーキルン炉、バッチ式炉、シャフト炉等の公知の炭化装置(図示せず)で炭化し、次に、得られた炭化物を、必要に応じて公知のカッターミルを1回または複数回通して種々の粒度に破砕し、さらに篩分け等により粒度調整して製造される。バインダーとしては、無機系のベントナイト、有機系のカルボキシメチルセルロース、コーンスターチ等を用いることができる。 The carbide molded body (heat raising material for converter) of the present invention is produced by adding a binder and water to carbide powder as the main raw material, mixing and stirring with a known mixer (not shown), and then using a known molding device. (See FIGS. 3 and 4) and then dried to a predetermined moisture content. The main raw material, carbide powder, is produced by first carbonizing raw materials such as coal, plant-based biomass, and waste plastic using a known carbonization device (not shown) such as a rotary kiln furnace, batch furnace, or shaft furnace. Next, the obtained carbide is crushed into various particle sizes by passing it through a known cutter mill once or multiple times as necessary, and the particle size is further adjusted by sieving or the like. As the binder, inorganic bentonite, organic carboxymethyl cellulose, cornstarch, etc. can be used.

公知のカッターミルとして、図2では、ロータリーキルン炉等で乾留された炭材21が、ロールクラッシャー(カッターミル)26のホッパー27からクラッシャーロール28に供給され破砕されて粉砕物22となって、ベルトコンベヤー29で搬出される様子を概略的に示している。炭化物成型体の成型装置としては、公知の双ロール式ブリケットマシンや、ペレット製造機(ペレタイザー)などを用いることができる。図3では、粒度調整された炭材にバインダーと水を加えてミキサーで混錬された炭材の混錬物23が、双ロール式ブリケットマシン31のホッパー32から成型ロール33に供給され圧縮成型されて炭材の成型物24(ブリケット24a)となって、ベルトコンベヤー34で搬出される様子を概略的に示している。また図4では、同様の炭材の混錬物23が、ペレット製造機(ペレタイザー)41のホッパー42からスクリューフィーダー43に供給され圧縮されて押出成型され、さらにカッター44で所定長さに切断された成型物24(ペレット24b)となって、ベルトコンベヤー45で搬出される様子を概略的に示している。 As a known cutter mill, in FIG. 2, carbon material 21 carbonized in a rotary kiln or the like is supplied from a hopper 27 of a roll crusher (cutter mill) 26 to a crusher roll 28, and is crushed into a pulverized material 22, which is then transferred to a belt. It schematically shows how it is carried out on a conveyor 29. As a molding device for the carbide molded body, a known twin-roll briquette machine, a pelletizer, or the like can be used. In FIG. 3, a mixed material 23 of carbon material, which is obtained by adding a binder and water to carbon material whose particle size has been adjusted and kneading it in a mixer, is supplied from a hopper 32 of a twin-roll briquette machine 31 to a forming roll 33, and is compressed and molded. The figure schematically shows how the charcoal material molded product 24 (briquettes 24a) is conveyed out by a belt conveyor 34. Further, in FIG. 4, a similar kneaded material 23 of carbonaceous material is supplied from a hopper 42 of a pelletizing machine (pelletizer) 41 to a screw feeder 43, compressed and extruded, and further cut into a predetermined length by a cutter 44. The molded product 24 (pellet 24b) is conveyed out by a belt conveyor 45.

本発明の炭化物成型体中の炭化物が、最大粒径が前記炭化物成型体の代表長さdの1/2未満の粒径を有するものとするのは、転炉用昇熱材の製造時のバインダー濃度を不必要に増大させないためである。すなわち、炭化物粉粒体を造粒する際に、大粒子間に小粒子が入り込んで密充填されるとの期待に反して、場所によっては大粒子間に小粒子が入り込まない部分が発生する場合があるが、このような現象は、後述の予備実験結果で説明するとおり、最大粒径が前記炭化物成型体の代表長さdの1/2以上で特に顕著となる。そのため、このような大粒子間でもバインダーを含む水の液架橋付着力により粒子が結合するものの、最大粒径が前記炭化物成型体の代表長さdの1/2以上で大粒子間が広く空いて間隔が広がるようになると、大きな液架橋付着力が必要となり、バインダー濃度を高める必要があるからである。 The carbide in the carbide molded body of the present invention has a maximum particle size of less than 1/2 of the representative length d of the carbide molded body during the production of the heat raising material for a converter. This is to prevent the binder concentration from increasing unnecessarily. In other words, when granulating carbide powder, contrary to the expectation that small particles will fit between large particles and form a dense packing, there may be some areas where small particles do not fit between large particles. However, as will be explained later in the preliminary experiment results, such a phenomenon becomes particularly noticeable when the maximum grain size is 1/2 or more of the representative length d of the carbide molded body. Therefore, although such large particles are bound together by the liquid bridge adhesive force of water containing a binder, when the maximum particle size is 1/2 or more of the representative length d of the carbide molded body, there are large spaces between the large particles. This is because if the distance becomes wider, a greater liquid crosslinking adhesive force will be required, and the binder concentration will need to be increased.

ここで、本発明の炭化物成型体(転炉用昇熱材)の代表長さdについて説明する。すなわち、代表長さdとは、転炉用昇熱材にかかる重力とその外形に応じて転炉排ガスから受ける抗力との釣り合い関係を取り扱うときの転炉用昇熱材の外形を代表させる長さである。この代表長さを用いて、たとえば転炉排ガスから受ける抗力との釣り合い関係から重力の方が小さくなる代表長さの昇熱材を用いれば、昇熱材が転炉排ガスとともに浮上して、昇熱材を溶湯まで投入することができなくなることを事前に検討することができる。なお、転炉用昇熱材がペレット形状の場合の代表長さdは、ペレット径で代表させ、転炉用昇熱材がブリケット形状の場合の代表長さdは、最大対角長さで代表させることができる。 Here, the representative length d of the carbide molded body (heat raising material for converter) of the present invention will be explained. In other words, the representative length d is the length that represents the external shape of the converter heating material when dealing with the balance between the gravity applied to the converter heating material and the drag force received from the converter exhaust gas depending on its external shape. It is. Using this representative length, for example, if a heating material of a representative length is used whose gravity is smaller than the drag force received from the converter exhaust gas, the heating material will float together with the converter exhaust gas and rise It is possible to consider in advance that it will not be possible to introduce the heating material to the molten metal. In addition, when the heat-raising material for a converter is in the form of pellets, the representative length d is represented by the pellet diameter, and when the heat-raising material for the converter is in the shape of a briquette, the representative length d is the maximum diagonal length. can be represented.

また、本発明の炭化物成型体中の炭化物が、大粒径側が70体積%、小粒径側が30体積%となるように区分したときの、大粒径側の炭化物のメジアン粒径D50と小粒径側の炭化物のメジアン粒径D50の比が1.5~2.3となるようにするのは、後述の予備実験および実施例で説明するとおり、大小の粒子を配合しない場合よりも空隙率が低下し、その空隙率の変化率も小さく空隙率の許容できる範囲に広い幅を持つため、製造の際のばらつきを考慮しても炭化物成型体の異常が発生せず製品歩留まりを高く維持できるためである。 In addition, when the carbide in the carbide molded body of the present invention is divided so that the large particle size side is 70% by volume and the small particle size side is 30% by volume, the median particle size D50 of the carbide on the large particle size side and the small Setting the ratio of the median particle size D50 of the carbide on the particle size side to be 1.5 to 2.3 is because, as explained in the preliminary experiments and examples below, the voids are smaller than when large and small particles are not mixed. The rate of change in porosity is small and the allowable range of porosity has a wide range, so even if manufacturing variations are taken into account, abnormalities in carbide molded bodies do not occur and product yields are maintained at a high level. This is because it is possible.

ここで、本発明の転炉用昇熱材(炭化物成型体)中の炭化物粒子のメジアン粒径の比の測定について説明する。まず、転炉用昇熱材(炭化物成型体)を水につけてバインダーを溶かした後、ろ過を行い炭化物を採取して純水もしくはメタノールで洗浄してから、レーザ回折粒度分布測定(JIS Z 8825:2013 粒子径解析-レーザ回折・散乱法)により、炭化物粒子の粒度分布を求める。次に、その粒度分布についてコンピューター解析することにより、大粒径側が70体積%、小粒径側が30体積%となるように区分したときの、大粒径側の炭化物のメジアン粒径D50と小粒径側の炭化物のメジアン粒径D50の比を求めることができる。なお、ここでのメジアン粒径D50とは、横軸に粒径をとり、縦軸に粒子量の累積値を体積百分率(%)で表した体積基準の積算分布曲線において、その累積値が50%にあたる粒径を読み取って定めるものである。 Here, measurement of the ratio of the median particle size of carbide particles in the heat raising material for a converter (carbide molded body) of the present invention will be explained. First, the heat-raising material (carbide molded body) for converter is soaked in water to dissolve the binder, then filtered to collect the carbide, washed with pure water or methanol, and then subjected to laser diffraction particle size distribution measurement (JIS Z 8825 :2013 Determine the particle size distribution of carbide particles by particle size analysis (laser diffraction/scattering method). Next, by computer analysis of the particle size distribution, when the large particle size side is divided into 70 volume % and the small particle size side is 30 volume %, the median particle size D50 of the carbide on the large particle size side and the small The ratio of the median particle size D50 of carbides on the particle size side can be determined. Note that the median particle size D50 here refers to a volume-based integrated distribution curve in which the horizontal axis represents the particle size and the vertical axis represents the cumulative value of particle amount in volume percentage (%). It is determined by reading the particle size corresponding to %.

一方、本発明の転炉用昇熱材の製造方法において、炭化物成型体の主原料である炭化物粉粒体のメジアン粒径の比の測定については、所定粒径毎の篩目毎に炭化物粉粒体を篩分けして炭化物粉粒体の粒度分布を求め、その粒度分布について、上記の炭化物成型体中の炭化物粒子のメジアン粒径の比の求め方と同様の方法で求めることができる。なお、炭化物成型体の原料である炭化物粉粒体でのメジアン粒径の比の測定結果と、その炭化物粉粒体から製造された炭化物成型体中の炭化物粒子のメジアン粒径の比の測定結果とは、原理的にも統計的にも等しいものと扱うことができる。 On the other hand, in the method for producing a heat raising material for a converter of the present invention, the ratio of the median particle size of the carbide powder, which is the main raw material of the carbide molded body, is measured by The particle size distribution of the carbide powder is determined by sieving the particles, and the particle size distribution can be determined in the same manner as the method for determining the median particle size ratio of the carbide particles in the carbide molded body described above. In addition, the measurement results of the ratio of the median particle size of the carbide powder, which is the raw material for the carbide molded body, and the ratio of the median particle size of the carbide particles in the carbide molded body manufactured from the carbide powder and granule. can be treated as being equivalent both in principle and statistically.

このような炭化物粒径の範囲についての予備実験の結果について次に説明する。
本発明者らは、まず、炭化物粉粒体を成型して得られる炭化物成型体(転炉用昇熱材)の圧潰強度と炭化物粒子の充填率の関係について検討した。一般に、充填率が高いと、粒子間隙の毛管吸引力が高まることや粒子同士が互いの凹凸部に接合するといった機械的接合の効果が作用するため、圧潰強度と充填率(=1-空隙率)は比例することが知られている。
The results of preliminary experiments regarding such a range of carbide particle sizes will be explained next.
The present inventors first studied the relationship between the crushing strength of a carbide molded body (heat raising material for a converter) obtained by molding carbide powder and the filling rate of carbide particles. In general, when the filling rate is high, mechanical bonding effects such as an increase in the capillary suction force between particles and particles bonding to each other's uneven parts occur, so the crushing strength and filling rate (= 1 - porosity ) is known to be proportional.

充填率に関しては、Horsfieldによる充填モデルが知られており、単一粒径φの真球粒子を六方最密充填とした場合、空隙率は25.9%となる。更に、真球粒子間の残りの空間に先の真球粒子径φに対し、0.414φの真球粒子を充填することで、空隙率は20.7%とすることができる。しかしながら、炭化物を成型する場合、充填構造が六方最密充填にはなっておらず、粒形が真球でもなく、さらに粒径が均一ではなく分布を持つため、Horsfieldによる充填モデルの適用は難しい。 Regarding the filling rate, the filling model by Horsfield is known, and when true spherical particles with a single particle diameter φ are hexagonally close-packed, the porosity is 25.9%. Furthermore, by filling the remaining space between the true spherical particles with true spherical particles having a true spherical particle diameter φ of 0.414φ, the porosity can be set to 20.7%. However, when molding carbide, it is difficult to apply Horsfield's filling model because the packing structure is not hexagonal close-packed, the grain shape is not a true sphere, and the grain size is not uniform and has a distribution. .

そこで、炭化物の充填率を高めて炭化物成型体の圧潰強度を高めるための予備実験として、バイオマス炭化物をペレットに成型する場合について、まず、ペレット径A(A=20mm)の整数分割相当(1/2A、1/3A、1/4A、1/5A、1/6A)の平均粒子径を持つ炭化物群を、原料の炭化物の粉砕、篩い分けにより粒度調整して準備した。これらの炭化物群のうち、大粒子径側の炭化物群としては、1/2A、1/3A、1/4A、1/5Aの4つの群とし、小粒子径側の炭化物群としては、1/3A、1/4A、1/5A、1/6Aの4つの群として、表1に示す10組の組み合わせについて検討することにした。図5は、このような10組の炭化物の組合せのうち、一例としての4種類の粒子径比(1.3、2.0、2.5、3.0)となる組について、各組内の小粒子の体積割合(配合比)を変化させた試料毎の空隙率(=1-充填率)を測定した結果を示すものである。なお、このときの条件毎の各々の試料は、各組内の小粒子の体積割合(配合比)を変化させた炭化物の混合物毎に、バインダーとして炭化物の8質量%のコーンスターチと適当な水を添加して混錬し、その後にペレタイザーで成型してペレットの成型品とし、さらに含水率3質量%以内となるように乾燥させて供試材としたものである。また、表1には、図5および図5と同等の図(図5で表示していない粒子径比でのデータを含むもの)から読み取れる最小空隙率も併記した。 Therefore, as a preliminary experiment to increase the filling rate of carbide and increase the crushing strength of the carbide molded body, we first conducted an integer division equivalent (1/ A carbide group having an average particle size of 2A, 1/3A, 1/4A, 1/5A, 1/6A) was prepared by adjusting the particle size by grinding and sieving the raw material carbide. Among these carbide groups, the carbide groups on the large particle size side are 1/2A, 1/3A, 1/4A, and 1/5A, and the carbide groups on the small particle size side are 1/2A, 1/3A, 1/4A, and 1/5A. We decided to study 10 combinations shown in Table 1 as four groups: 3A, 1/4A, 1/5A, and 1/6A. FIG. 5 shows, as an example, four types of particle size ratios (1.3, 2.0, 2.5, 3.0) among these 10 carbide combinations, and the graph shows the difference in each group. This shows the results of measuring the porosity (=1-filling ratio) of each sample with varying volume ratios (mixing ratios) of small particles. In addition, each sample for each condition at this time was prepared by adding cornstarch containing 8% by mass of carbide as a binder and appropriate water for each carbide mixture in which the volume ratio (mixing ratio) of small particles in each set was changed. The material was added and kneaded, and then molded with a pelletizer to obtain a pellet molded product, which was further dried to a moisture content of 3% by mass or less to obtain a test material. Table 1 also lists the minimum porosity that can be read from FIG. 5 and a diagram equivalent to FIG. 5 (including data at particle diameter ratios not shown in FIG. 5).

Figure 2023132282000002
Figure 2023132282000002

図5から小粒子径と大粒子径との配合比によって空隙率が変化し、小粒子の体積割合が0.3付近で最小値を取ることが分かる。また図5から、空隙率の変化は、粒子径の比で層別して整理できることも分かる。図6は、このように層別して整理できる転炉用昇熱材中の炭化物の大粒径と小粒径の粒子径比を横軸に取り、転炉用昇熱材の炭化物成型体の最小空隙率を縦軸に取って、これらの関係をまとめた図である。この図6から、炭化物の粒子径比(大粒子径/小粒子径)を大きくすることで、最小空隙率を低下させることができることが分かる。このことから、さらに空隙を埋めるための添加水分量を低減させることができると推測された。 It can be seen from FIG. 5 that the porosity changes depending on the blending ratio of small particle size and large particle size, and takes a minimum value when the volume ratio of small particles is around 0.3. Furthermore, from FIG. 5, it can be seen that the change in porosity can be organized by stratification based on the ratio of particle diameters. Figure 6 shows the minimum particle size ratio of the carbide molded body of the heat-raising material for a converter, with the horizontal axis plotting the particle size ratio between large and small grains of the carbide in the heat-raising material for a converter, which can be stratified and organized in this way. FIG. 2 is a diagram summarizing these relationships with the porosity as the vertical axis. It can be seen from FIG. 6 that the minimum porosity can be reduced by increasing the particle size ratio (large particle size/small particle size) of carbide. From this, it was presumed that the amount of water added to fill the voids could be further reduced.

ただし、組No.3、4では、粒子径比が大きく、最小空隙率をそれぞれ、0.32、0.25と大きく低減させることができるものの、図5から分かるとおり炭化物粒子の配合比による空隙率の変化が大きい。そのため、製造の際のばらつきによって、添加水分量が適正値よりも多くなり、成型後、乾燥前の炭化物成型体にラミネーションなどの異常が発生して製品歩留まりが低下することが懸念される。一方で、組No.1、2、5~10は、空隙率は組No.3、4には劣るものの、空隙率が最小となる配合比の近辺の空隙率の変化率が小さく、空隙率の許容できる範囲に広い幅を持つため、製造の際のばらつきを考慮しても、炭化物成型体の異常が発生せず、高い製品歩留まりが得られることが期待される。このため、空隙率は組No.3、4には劣るものの、大小の粒子を配合しない場合(空隙率0.39)よりも空隙率が2~5%低下し、製造の際のばらつきを考慮しても、炭化物成型体の異常が発生せず、製品歩留り低下の無い、組No.1、2、7、9が適当だと判断した。 However, group no. In samples 3 and 4, the particle diameter ratio is large and the minimum porosity can be greatly reduced to 0.32 and 0.25, respectively, but as can be seen from Figure 5, the porosity changes greatly depending on the blending ratio of carbide particles. . Therefore, due to variations during manufacturing, the amount of added water may be higher than the appropriate value, and there is a concern that abnormalities such as lamination may occur in the carbide molded product after molding and before drying, resulting in a decrease in product yield. On the other hand, group no. 1, 2, 5 to 10, the porosity is group No. Although it is inferior to 3 and 4, the rate of change in porosity near the mixing ratio that minimizes porosity is small, and the allowable range of porosity has a wide range, even when manufacturing variations are taken into account. It is expected that no abnormalities will occur in the carbide molded body and that a high product yield will be obtained. Therefore, the porosity of group No. Although inferior to 3 and 4, the porosity is 2 to 5% lower than when large and small particles are not mixed (porosity 0.39), and even when manufacturing variations are taken into account, abnormalities in the carbide molded body are not observed. Group No. 1, which does not occur and does not cause a decrease in product yield. I decided that 1, 2, 7, and 9 were appropriate.

上記のとおり、図6から、炭化物の粒子径比を大きくすることで、最小空隙率を低下させることができ、さらに空隙を埋めるための添加水分量を低減させることができることが推測されることから、さらに推し進めて、転炉用昇熱材の成型の際に必要なバインダー量の低減の可能性を検討することにした。図7は、炭化物成型体の代表長さdに対する大粒径側の炭化物のメジアン粒径D50の比と転炉用昇熱材の成型の際に必要なバインダー濃度との関係をまとめた図である。図7によると、大粒子として、1/2Aのように大きな径を持つ粒子を用いた場合、必要なバインダー濃度が増加することが判明した。この原因として次のようなことが推定される。すなわち、造粒の際、大粒子間に小粒子が入り込むため、密充填されることを期待しているが、場所によっては大粒子間に小粒子が入り込まない部分がどうしても発生してしまう。この部分では、大粒子間でバインダーを含む水の液架橋付着力により粒子が結合する。大粒子間の間隔が広いほど、大きな液架橋付着力が必要となり、そのためにバインダー濃度を高める必要があると推定される。実際に、組No.2の様に、大粒子に1/2Aを用いた場合では、組No.7の様に、大粒子に1/3Aを用いた場合と比較して、高いバインダー濃度を必要とした。このため、組No.2よりも、組No.7の方が、バインダー量は低下した。 As mentioned above, from Figure 6, it is inferred that by increasing the particle size ratio of carbide, the minimum porosity can be lowered, and the amount of water added to fill the voids can be further reduced. We decided to take this further and investigate the possibility of reducing the amount of binder required when molding heat raising materials for converters. FIG. 7 is a diagram summarizing the relationship between the ratio of the median particle size D50 of carbide on the large particle size side to the representative length d of the carbide molded body and the binder concentration required when forming a heat raising material for a converter. be. According to FIG. 7, it was found that when particles having a large diameter such as 1/2A were used as the large particles, the required binder concentration increased. The following is presumed to be the cause of this. That is, during granulation, small particles enter between the large particles, so it is expected that they will be tightly packed, but depending on the location, there will inevitably be areas where the small particles do not enter between the large particles. In this part, the particles are bonded together by the liquid bridge adhesive force of water containing a binder between the large particles. It is presumed that the wider the spacing between the large particles, the greater the liquid bridge adhesion force required, and therefore the need to increase the binder concentration. In fact, group no. In the case where 1/2A is used for large particles as in case No. 2, group No. 7, a higher binder concentration was required compared to the case where 1/3A was used for large particles. For this reason, group no. Group No. 2 is better than Group No. 2. The amount of binder was lower in No. 7.

以上のような予備実験結果および後述の実施例から、本発明の転炉用昇熱材に含まれる炭化物は、まず、バインダー濃度を不必要に増大させないために、(a)最大粒径が転炉用昇熱材(炭化物成型体)の代表長さdの1/2未満の粒径を有するものとし、同時に、好ましい制御範囲を確保するために、(b)大粒径側が70体積%、小粒径側が30体積%となるように区分したときの、大粒径側の炭化物のメジアン粒径D50と小粒径側の炭化物のメジアン粒径D50の比が、1.5~2.3であるようにする。 From the above preliminary experimental results and the examples described later, it is clear that the carbides contained in the heat raising material for converters of the present invention are (a) It shall have a particle size less than 1/2 of the representative length d of the heating material for the furnace (carbide molded body), and at the same time, in order to ensure a preferable control range, (b) 70% by volume on the large particle size side, When divided so that the small particle size side is 30% by volume, the ratio of the median particle size D50 of the carbide on the large particle size side to the median particle size D50 of the carbide on the small particle size side is 1.5 to 2.3. so that it is.

本発明の転炉用昇熱材の圧潰強度は、490N/個以上であるのが好ましい。昇熱材の圧潰強度が490N/個未満である場合は、昇熱材が溶鋼へ着湯するまでに破砕して粉塵となり転炉排ガスとともに飛散してしまい、昇熱材を歩留まり高く溶湯まで投入することができないためである。 It is preferable that the crushing strength of the heat raising material for a converter of the present invention is 490 N/piece or more. If the crushing strength of the heating material is less than 490N/piece, the heating material will be crushed into dust before it reaches the molten steel and will be scattered with the converter exhaust gas, making it difficult to feed the heating material into the molten metal with a high yield. This is because it is not possible to do so.

以下、本発明の実施例について説明する。 Examples of the present invention will be described below.

炭化物原料として、製材端材や林地残材等の木質原料を用いることとし、650℃で加熱炭化したバイオマス炭材を被成型物に供することにした。 As the carbide raw material, we decided to use woody raw materials such as lumber scraps and forest residues, and we decided to use biomass charcoal material that was heated and carbonized at 650° C. for the molded object.

実施例に供した転炉用昇温材の形状は、直径20mmのペレット形状のものと、一辺50mmのブリケット形状のものとした。このときのバイオマス炭材の粉砕物粒度目標値は、概ね「最大粒径が炭化物昇熱材の代表長さdの1/2未満の粒径を有するもの」との要件を満たすように、直径20mmのペレット形状の場合は9mm以下、一辺50mmのブリケット形状の場合は22mm以下とすることにした。 The shapes of the temperature increasing materials for a converter used in the examples were a pellet shape with a diameter of 20 mm and a briquette shape with a side of 50 mm. At this time, the target value of the particle size of the pulverized biomass carbonaceous material is set such that the diameter In the case of a pellet shape of 20 mm, the diameter was determined to be 9 mm or less, and in the case of a briquette shape of 50 mm on a side, the diameter was determined to be 22 mm or less.

このような粉砕物粒度の目標値に従って、上記のバイオマス炭材を、前述した予備実験と同様に、図2に示したロールクラッシャー(カッターミル)26に1回または複数回通した後、篩分けして得られた種々の平均粒子径のバイオマス炭の粉砕物を準備した。さらに、これら種々の平均粒子径のバイオマス炭の粉砕物を組み合わせて、大粒径側が70体積%、小粒径側が30体積%となるように区分したときの、大粒径側の炭化物のメジアン粒径D50と小粒径側の炭化物のメジアン粒径D50の比が、表2に示すとおりの1.3から2.5の範囲の炭化物粉粒体の混合物を5組分調合した。調合した5組の炭化物粉粒体のそれぞれの粒度分布を、図8、図9に示す。 According to the target value of the particle size of the pulverized material, the biomass carbonaceous material is passed through the roll crusher (cutter mill) 26 shown in FIG. 2 once or multiple times, and then sieved. Pulverized biomass charcoal with various average particle diameters was prepared. Furthermore, when these crushed biomass chars with various average particle sizes are combined and divided into 70% by volume on the large particle size side and 30% by volume on the small particle size side, the median of the charcoal on the large particle size side is Five sets of carbide powder mixtures were prepared in which the ratio of the particle size D50 to the median particle size D50 of the carbide on the small particle size side ranged from 1.3 to 2.5 as shown in Table 2. The particle size distributions of the five sets of prepared carbide powders are shown in FIGS. 8 and 9.

次に、表2に示す混合条件で、5組の炭化物粉粒体のそれぞれにバインダーのコーンスターチと水を加えて混合して、図3に示す双ロール式ブリケットマシンまたは図4に示すペレタイザーで、ブリケットまたはペレットに圧縮成形した。成型後は、5日間常温で静置して、含有水分量が3%程度まで乾燥させて転炉用昇熱材とした。 Next, under the mixing conditions shown in Table 2, corn starch and water as a binder were added to each of the five sets of carbide powder and granules and mixed, using a twin roll briquette machine shown in FIG. 3 or a pelletizer shown in FIG. 4. Compression molded into briquettes or pellets. After molding, the molded material was allowed to stand at room temperature for 5 days and dried to a moisture content of approximately 3%, thereby producing a heat-raising material for a converter.

比較例1では、表2、図8(a)に示されるとおり、粒子径比が1.3と小さく大粒子間の隙間を埋める小粒子が少ないため最小空隙率を低下させることがほとんどできず、大粒子間の隙間を埋めるための添加水分量が増大しこれに伴って添加バインダー量が5組の中で一番大きくなった。また、乾燥後の炭化物成型体のn=10の抜き取りをした圧潰強度も、比較例1では、操業で必要となる490N以上の圧潰強度を達成することができなかった。 In Comparative Example 1, as shown in Table 2 and FIG. 8(a), the particle size ratio was small at 1.3, and there were few small particles filling the gaps between large particles, so it was almost impossible to reduce the minimum porosity. The amount of water added to fill the gaps between large particles increased, and the amount of binder added became the largest among the five sets. Furthermore, in Comparative Example 1, the crushing strength of the dried carbide molded body obtained by sampling n=10 could not achieve the crushing strength of 490 N or more required for operation.

また、比較例2では、表2、図9(b)に示されるとおり、粒子径比が2.5と大きく最小空隙率が低くなり、大粒子間の隙間を埋めるための添加水分量が少なくなり、これに伴って添加バインダー量が5組の中で本発明例3とともに一番少なくなった。しかし、粒子径比が大きいため炭化物粒子の配合比による空隙率の変化が大きく(図5参照)、製造の際のばらつきによって添加水分量が適正値よりも多くなり易いこともあり、成型後、乾燥前の炭材にラミネーションなどの異常が発生して製品歩留りが著しく低下し、圧潰強度の試験材を揃えることができないほどだった。 In addition, in Comparative Example 2, as shown in Table 2 and FIG. 9(b), the particle size ratio is large at 2.5, and the minimum porosity is low, and the amount of water added to fill the gaps between large particles is small. Accordingly, the amount of added binder was the smallest among the five sets together with Invention Example 3. However, since the particle size ratio is large, the porosity changes greatly depending on the blending ratio of carbide particles (see Figure 5), and the amount of added water tends to be higher than the appropriate value due to variations in manufacturing. Abnormalities such as lamination occurred in the carbon material before drying, resulting in a significant drop in product yield, to the point that it was not possible to prepare materials for crushing strength testing.

一方、本発明例1~3では、ペレット形状、ブリケット形状の形状の違いにかかわらず、操業で必要となる圧潰強度と歩留りを維持しながら、バインダー量を低減することができた。 On the other hand, in Examples 1 to 3 of the present invention, the amount of binder could be reduced while maintaining the crushing strength and yield required for operation, regardless of the difference in shape between pellets and briquettes.

Figure 2023132282000003
Figure 2023132282000003

1 転炉本体
2 上吹きランス
3 底吹き羽口
4 煙道
5 スカート
6 ホッパー
7 投入シュート
8 溶銑
9 スラグ
10 転炉排ガス
21 炭材(バイオマス炭材)(乾留物)
22 炭材(バイオマス炭材)粉砕物
23 炭材(バイオマス炭材)混錬物
24 炭材(バイオマス炭材)成型物
24a ブリケット
24b ペレット
26 ロールクラッシャー(カッターミル)
27 ホッパー
28 クラッシャーロール
29 ベルトコンベヤー
31 双ロール式ブリケットマシン
32 ホッパー
33 成型ロール
34 ベルトコンベヤー
41 ペレット製造機(ペレタイザー)
42 ホッパー
43 スクリューフィーダー
44 カッター
45 ベルトコンベヤー

1 Converter main body 2 Top blowing lance 3 Bottom blowing tuyere 4 Flue 5 Skirt 6 Hopper 7 Charge chute 8 Hot metal 9 Slag 10 Converter exhaust gas 21 Carbon material (biomass carbon material) (carbonized product)
22 Pulverized carbon material (biomass carbon material) 23 Kneaded material of carbon material (biomass carbon material) 24 Molded material of carbon material (biomass carbon material) 24a Briquette 24b Pellet 26 Roll crusher (cutter mill)
27 Hopper 28 Crusher roll 29 Belt conveyor 31 Twin roll briquette machine 32 Hopper 33 Forming roll 34 Belt conveyor 41 Pellet making machine (pelletizer)
42 Hopper 43 Screw feeder 44 Cutter 45 Belt conveyor

Claims (4)

炭化物粉粒体とバインダーとで成型してなる炭化物成型体の転炉用昇熱材であって、
前記炭化物成型体中の炭化物は、
(a) 最大粒径が前記炭化物成型体の代表長さdの1/2未満の粒径を有するものであり、
(b) 大粒径側が70体積%、小粒径側が30体積%となるように区分したときの、大粒径側の炭化物のメジアン粒径D50と小粒径側の炭化物のメジアン粒径D50の比が、1.5~2.3であることを特徴とする、転炉用昇熱材。
A heating material for a converter of a carbide molded body formed by molding a carbide powder and a binder,
The carbide in the carbide molded body is
(a) The maximum particle size is less than 1/2 of the representative length d of the carbide molded body,
(b) Median particle size D50 of carbide on the large particle size side and median particle size D50 of carbide on the small particle size side when divided so that the large particle size side is 70 volume % and the small particle size side is 30 volume % A heat raising material for a converter, characterized in that the ratio of
前記転炉用昇熱材は、圧潰強度が490N/個以上であることを特徴とする、請求項1に記載の転炉用昇熱材。 The heat-raising material for a converter according to claim 1, wherein the heat-raising material for a converter has a crushing strength of 490 N/piece or more. 炭化物粉粒体とバインダーとで成型してなる炭化物成型体の転炉用昇熱材の製造方法であって、
石炭、植物系バイオマス、廃プラスチックの群から選択される少なくとも1つを炭化して炭化物原料を製造し、
前記炭化物原料に対し、1または複数の篩分け処理および1または複数の破砕処理を施して、
(a’) 前記炭化物原料から、最大粒径が前記炭化物成型体の代表長さdの1/2未満となる範囲内で、粒度の異なる複数の群に区分けされた前記炭化物粉粒体を得るようにし、さらに、
(b’) 得られた前記炭化物粉粒体を、大粒径側が70体積%、小粒径側が30体積%となるように区分したときの、大粒径側の炭化物のメジアン粒径D50と小粒径側の炭化物のメジアン粒径D50の比が、1.5~2.3の範囲となるように調合して前記成型前の前記炭化物粉粒体とする
ことを特徴とする、転炉用昇熱材の製造方法。
A method for producing a heating material for a converter of a carbide molded body formed by molding a carbide powder and a binder, the method comprising:
producing a carbide raw material by carbonizing at least one selected from the group of coal, plant biomass, and waste plastic;
The carbide raw material is subjected to one or more sieving treatments and one or more crushing treatments,
(a') Obtaining from the carbide raw material the carbide powder which is divided into a plurality of groups with different particle sizes within a range where the maximum particle size is less than 1/2 of the representative length d of the carbide molded body. In addition,
(b') When the obtained carbide powder is divided into 70% by volume on the large particle side and 30% by volume on the small particle side, the median particle size D50 of the carbide on the large particle size side A converter, characterized in that the carbide powder before molding is prepared so that the ratio of the median particle size D50 of the carbide on the small particle size side is in the range of 1.5 to 2.3. Method of manufacturing heat-raising material for use.
前記転炉用昇熱材は、圧潰強度が490N/個以上であることを特徴とする、請求項3に記載の転炉用昇熱材の製造方法。

4. The method for producing a heat-raising material for a converter according to claim 3, wherein the heat-raising material for a converter has a crushing strength of 490 N/piece or more.

JP2022037508A 2022-03-10 2022-03-10 Converter heating material and method for producing the same Pending JP2023132282A (en)

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