JP2009185315A

JP2009185315A - Method for granulating raw material to be sintered

Info

Publication number: JP2009185315A
Application number: JP2008024634A
Authority: JP
Inventors: Hirotaka Nishina; 宏隆仁科; Koji Araya; 孝治荒谷; Akira Kihara; 彰木原; Shigenori Matsuoka; 重典松岡; Keijiro Kawasaki; 恵二郎河崎; Masakazu Shiozuka; 政和塩塚; Hiroshi Shimokubo; 洋志下久保
Original assignee: Nisshin Steel Co Ltd
Current assignee: Nippon Steel Nisshin Co Ltd
Priority date: 2008-02-05
Filing date: 2008-02-05
Publication date: 2009-08-20

Abstract

<P>PROBLEM TO BE SOLVED: To improve the productivity of sintered ore by improving the granulating property of a raw material to be sintered in a method for granulating the raw material to be sintered, in which iron ore powder, sintered returning ore, auxiliary material, solid fuel and others are blended, and suppressing the disintegration of pseud-grain even in a moisture cohesion zone (wetting zone) in the lower part of filling-up layer during sintering. <P>SOLUTION: The raw material to be sintered, in which the iron ore powder, the sintered returning ore, the auxiliary material, the solid fuel and others are blended, is charged into a primary mixer 2, and stirred/mixed by adding water. The obtained mixed raw material is conveyed toward a secondary mixer 3, is added with chaffs of 0.01-2 wt.% in the middle of the conveyance, and is kneaded in the secondary mixer 3, thereby filling voids of the chaffs with fine powders of the raw material to be sinntered, remaining without being granulated in the primary mixer 2 and granulating them to increase grain size and strength. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、焼結鉱の焼結原料の造粒性が向上すると共に、焼結時の通気性を向上させる焼結原料の造粒方法に関する。 The present invention relates to a method for granulating a sintered material that improves the granulation property of the sintered raw material of sintered ore and improves the air permeability during sintering.

通常、高炉用原料である焼結鉱は、概略以下の工程で製造される。
まず、約１０mm以下の粒度の鉄鉱石粉に、同程度の粒度の焼結返鉱と、約３mm以下の粒度の珪石、石灰石、蛇紋石などの副原料と、コークス粉、石炭粉などの固体燃料と、生石灰、消石灰等を撹拌混合し、配合水を添加して造粒させて擬似粒子化、すなわち粗い粒子を核とし、その表面に微細な粒子を水の表面張力により付着させて粒子群を形成する。次にこうして得られた混合原料を、乾燥後、焼結機、例えばドワイトロイド式焼結機のパレット上に充填し、層頂部の混合原料中の固体燃料に着火する。着火後、下方に向けて空気を吸引しながら固体燃料を燃焼させ、この燃焼熱により充填した混合原料を焼結させて焼結ケーキとするもので、混合原料を乾燥後、１１５０〜１２００℃へ加熱することにより、混合原料中の鉄鉱石と副原料とのスラグ反応により融液が生成される。この融液により鉄鉱石粉の液相焼結が行われる。冷却後、この融液による鉄鉱石粉の結合により必要な焼結鉱の強度が得られるようになっている。 Usually, the sintered ore which is a raw material for blast furnaces is manufactured in the following processes.
First, iron ore powder with a particle size of about 10 mm or less, sintered reversion with the same particle size, auxiliary materials such as silica, limestone and serpentine with a particle size of about 3 mm or less, and solid fuel such as coke powder and coal powder Then, quick lime, slaked lime, etc. are agitated and mixed, mixed water is added and granulated to make pseudo particles, that is, coarse particles are used as nuclei, and fine particles are attached to the surface by the surface tension of water to form a particle group. Form. Next, the mixed raw material thus obtained is dried and then filled on a pallet of a sintering machine, for example, a Dwytroid type sintering machine, and the solid fuel in the mixed raw material at the top of the layer is ignited. After ignition, solid fuel is combusted while sucking air downward, and the mixed raw material filled with this combustion heat is sintered to form a sintered cake. After the mixed raw material is dried, it reaches 1150 to 1200 ° C. By heating, a melt is generated by a slag reaction between the iron ore in the mixed raw material and the auxiliary raw material. With this melt, liquid phase sintering of iron ore powder is performed. After cooling, the required strength of sintered ore can be obtained by combining the iron ore powder with the melt.

近年の鉄鉱石資源の変化に起因する鉄鉱石粉の微粉化傾向やリモナイト質鉱石の比率増加により、焼結原料の造粒性が悪化し、擬似粒子の強度が低下して崩壊しやすくなり（特に、焼結中の充填層下部の水分凝縮帯（湿潤帯）においては、上部からの荷重によって擬似粒子が崩壊しやすい）、混合原料の通気性が悪化して焼結に要する時間が長くなり、焼結鉱の生産能率が低下する傾向にある。 Due to the recent trend toward finer iron ore powder due to changes in iron ore resources and the increase in the ratio of limonite ore, the granulation property of the sintered raw material deteriorates, and the strength of the pseudo particles decreases, making it easy to collapse (particularly In the moisture condensation zone (wet zone) at the bottom of the packed bed during sintering, pseudo particles tend to collapse due to the load from the top), the air permeability of the mixed raw material deteriorates and the time required for sintering becomes longer, The production efficiency of sintered ore tends to decrease.

通気性を改善するための提案も種々なされ、その一つに焼結原料の混合造粒工程の後半以降、好ましくは焼結機パレット上に焼結原料を装入中にもみ殻、短く刻んだ藁、多孔質の木、草などの有機質よりなる有空隙物質を０．０５〜２重量％添加する方法が提案されている（特許文献１）。
特開昭５７−１４０８３５号 Various proposals have also been made to improve the air permeability, one of which is the latter half of the mixing granulation process of the sintering raw material, and preferably the rice husk is chopped shortly while charging the sintering raw material onto the sintering machine pallet. There has been proposed a method of adding 0.05 to 2% by weight of a porous substance made of an organic material such as firewood, porous wood, and grass (Patent Document 1).
JP-A-57-140835

特許文献１に開示される方法は、焼結原料に添加された有機質の有空隙物質がコークスの燃焼に先立って燃焼して消滅し、これによって形成される空隙を利用して通気性を改善させる方法である。 In the method disclosed in Patent Document 1, the organic porous substance added to the sintering raw material burns and disappears prior to the combustion of coke, and the air permeability is improved by utilizing the voids formed thereby. Is the method.

これに対し本発明は、焼結原料の造粒工程の途中に、焼結原料の微粉が入り込む開口部を備えた空隙を有する有底物質を装入し、それまでの造粒過程で造粒されずに残った焼結原料の微粉を開口部より空隙内に取り込んで焼結原料の造粒性を改善し、焼結中の充填層下部の水分凝集帯（湿潤帯）においても擬似粒子の崩壊を抑制し、焼結鉱の生産性を向上させようとするものである。 On the other hand, in the present invention, in the course of the granulation process of the sintered raw material, a bottomed substance having a void with an opening into which fine powder of the sintered raw material enters is charged, and granulation is performed in the previous granulation process. The remaining fine powder of the sintering raw material is taken into the gap through the opening to improve the granulation property of the sintering raw material, and in the moisture aggregation zone (wet zone) below the packed bed during sintering, It is intended to suppress collapse and improve the productivity of sintered ore.

したがって請求項１の発明は、焼結原料の微粉が入り込む開口部を備えた空隙を有する有底物質を焼結原料の撹拌混合による造粒工程の途中、詳細には、既存の造粒過程にて擬似粒子の増大化を目的とした造粒の効果が減少した以降に焼結原料に装入し、残った焼結原料内の微粉を有底物質の空隙内に取り込み、造粒後の焼結原料の粒度を、更に増大させることを特徴とする。 Therefore, in the invention of claim 1, in the middle of the granulation process by stirring and mixing the sintered raw material, the bottomed substance having an opening portion into which the fine powder of the sintered raw material enters, in detail, in the existing granulation process After the reduction of the effect of granulation for the purpose of increasing pseudo particles, the material is charged into the sintering raw material, and the remaining fine powder in the sintering raw material is taken into the voids of the bottomed material, followed by sintering after granulation. It is characterized by further increasing the particle size of the raw material.

請求項２の発明は、請求項１の前記発明において、鉄鉱石粉と焼結返鉱と副原料と固体燃料からなる焼結原料１００質量％に対し、前記有底物質を０．０１〜２質量％装入することを特徴とし、
請求項３の発明は、前記有底物質をもみ殻としたことを特徴とする。 The invention according to claim 2 is the invention according to claim 1, wherein 0.01 to 2 mass of the bottomed material is added to 100 mass% of the sintered raw material consisting of iron ore powder, sintered ore, auxiliary material and solid fuel. % Charging,
The invention of claim 3 is characterized in that the bottomed material is rice husk.

焼結原料の造粒工程の途中、すなわち造粒過程で焼結原料を撹拌混合により擬似粒子化した後に開口部を備えた空隙を有する有底物質を装入し、その後更に撹拌混合することで有底物質の空隙内に焼結原料の微粉が入り込み、造粒後の焼結原料の粒度が増大する。また焼結原料の微粉が有底物質の空隙内に入り込んで粒子が強化されたことにより、焼結中の充填層下部の水分凝集帯（湿潤帯）における擬似粒子の崩壊が抑制され、通気性が改善される。その結果、余分な設備を必要とすることなく、造粒工程の途中で有底物質を装入することで焼結原料の造粒性及び焼結時の通気性を向上させることができる。 In the middle of the granulation process of the sintering raw material, that is, the sintered raw material is made into pseudo particles by stirring and mixing in the granulating process, and then a bottomed substance having voids with openings is charged, and then further stirred and mixed. Fine powder of the sintering raw material enters the voids of the bottomed substance, and the particle size of the sintering raw material after granulation increases. In addition, the fine powder of the sintering raw material entered the voids of the bottomed material and strengthened the particles, so that the collapse of the pseudo particles in the water agglomeration zone (wet zone) below the packed bed during sintering was suppressed, and air permeability Is improved. As a result, it is possible to improve the granulation property of the sintering raw material and the air permeability during sintering by introducing a bottomed substance in the middle of the granulation step without requiring extra equipment.

図１は、本発明で用いる焼結鉱の製造装置を示すもので、原料槽１には各種銘柄の鉄鉱石粉、焼結返鉱、石灰石又は生石灰（若しくは消石灰）よりなる副原料、コークス粉又は無煙炭粉よりなる固体燃料、珪石等の各種焼結原料が入れられ、各原料槽１より一定量ずつ切り出された焼結原料がコンベヤにより１次ミキサー２に投入され、１次ミキサー２では焼結原料に一定量の水を配合して撹拌混合され、１次造粒が行われる。造粒工程は１次ミキサー２と２次ミキサー３による２次の造粒過程からなっており、１次造粒過程後、２次ミキサー３に向けて搬送される混合原料又は２次ミキサー３に送られた混合原料に開口部を備えた空隙を有する有底物質、例えばもみ殻、藁、スポンジ等の有機物質、貝殻やその破片よりなる無機物質が添加される。 FIG. 1 shows an apparatus for producing sintered ore used in the present invention. In the raw material tank 1, various materials such as iron ore powder, sintered ore, limestone or limestone (or slaked lime), an auxiliary material, coke powder or Various sintering raw materials such as solid fuel made of anthracite powder and silica stone are put, and the sintering raw material cut out from each raw material tank 1 by a certain amount is put into the primary mixer 2 by the conveyor and sintered in the primary mixer 2 A fixed amount of water is mixed with the raw material and mixed with stirring to perform primary granulation. The granulation process consists of a secondary granulation process by the primary mixer 2 and the secondary mixer 3, and after the primary granulation process, the mixed raw material conveyed to the secondary mixer 3 or the secondary mixer 3 A bottomed substance having a void with an opening, for example, an organic substance such as rice husk, straw, or sponge, or an inorganic substance made of shells or fragments thereof is added to the fed mixed raw material.

２次ミキサー３にて有底物質を加えた混合原料を撹拌混合し、混合原料に含まれている微粉を有底物質の空隙内に取り込む、２次ミキサー３から搬出された混合原料は、ドワイトロイド式焼結機４のパレット５に充填される。そして点火炉６で層頂部の混合原料中の固体燃料に着火される。着火後、混合原料は図の矢印方向に移送されながら、ウィンドボックス７を経、セットリングチャンバー８を通して吸引される空気で混合原料中の固体燃料を燃焼させ、この焼結熱で混合原料を焼結させるようになっている。 The mixed raw material to which the bottomed substance is added in the secondary mixer 3 is stirred and mixed, and the fine powder contained in the mixed raw material is taken into the void of the bottomed substance. The mixed raw material transported from the secondary mixer 3 is dwight. The pallet 5 of the Lloyd type sintering machine 4 is filled. Then, the solid fuel in the mixed raw material at the top of the layer is ignited in the ignition furnace 6. After ignition, the mixed raw material is transferred in the direction of the arrow in the figure, and the solid fuel in the mixed raw material is combusted by the air sucked through the wind box 7 and through the set ring chamber 8, and the mixed raw material is sintered by this sintering heat. It comes to tie.

前記実施形態では、１次ミキサーと２次ミキサーの二つのミキサーを用いて造粒工程が行われ、有底物質は１次ミキサーと２次ミキサー間で配合されるようになっているが、造粒工程を一つのミキサーで行い、水を添加して１次の造粒過程を終えたのち、同じミキサー内に有底物質を添加して２次の造粒過程を行うようにしてもよい。 In the above embodiment, the granulation process is performed using two mixers, a primary mixer and a secondary mixer, and the bottomed substance is blended between the primary mixer and the secondary mixer. The granulation process may be performed with one mixer, and after adding the water and completing the primary granulation process, the bottomed substance may be added into the same mixer to perform the secondary granulation process.

次に図１に示す焼結機を用いた焼結鉱製造法の具体例について説明する。
原料槽１より切り出したＴ．Ｆｅ：５５〜６８質量％、付着水分：約３〜１０質量％（外数）を含む粒径１０mm以下の粉鉄鉱石６０〜７０質量％（乾量基準）と、焼結返鉱１０〜３０質量％と、副原料として石灰石または生石灰（若しくは消石灰）８〜１２質量％と、必要により珪石少量と固体燃料としてコークス粉または無煙炭粉３〜５質量％を１次ミキサー２に投入し、適量の配合水を追加して合計水分量６〜９質量％として該ミキサー２で混練する。そして擬似粒子化した混合原料とする。 Next, a specific example of a method for producing sinter using the sintering machine shown in FIG. 1 will be described.
T. cut out from raw material tank 1 Fe: 55-68% by mass, adhering moisture: about 3-10% by mass (outside number) and a powdered iron ore with a particle size of 10 mm or less (60% to 70% by mass) (based on dry weight) 1% by mass of limestone or quicklime (or slaked lime) 8-12% by mass as a raw material, and if necessary, a small amount of silica stone and 3-5% by mass of coke powder or anthracite coal powder as a solid fuel are added to the primary mixer 2 The blended water is added and the mixture is kneaded with the mixer 2 to a total water content of 6 to 9% by mass. And it is set as the mixed raw material formed into pseudo particles.

次に得られたこの混合原料を２次ミキサー３に向けて搬送する間にもみ殻０．０１〜２質量％（乾量基準）添加し、２次ミキサー３にて混練してもみ殻を均一に分散させる。この混練によってもみ殻に第１のミキサー２で造粒されずに残った焼結原料の微粉がもみ殻の空隙内に取り込まれて造粒される。 Next, 0.01 to 2% by mass (dry basis) of rice husk is added while the mixed raw material thus obtained is conveyed toward the secondary mixer 3, and the rice husk is evenly mixed by kneading in the secondary mixer 3. To disperse. By this kneading, fine powder of the sintering raw material remaining in the rice husk without being granulated by the first mixer 2 is taken into the space of the rice husk and granulated.

こうして作製した混合原料を、ドワイトロイド式焼結機４のパレット５上に充填し、表層部の混合原料中のコークス粉または無煙炭粉に着火する。着火後、２０〜４５分間、ウィンドボックス７を介して下方に向けて空気を吸引することによりコークス粉または無煙炭粉を燃焼させ、この燃焼熱により充填した混合原料を焼結させて焼結ケーキとする。 The mixed raw material thus produced is filled on the pallet 5 of the dwelloid type sintering machine 4, and the coke powder or the anthracite coal powder in the mixed raw material in the surface layer portion is ignited. After ignition, the coke powder or the anthracite powder is burned by sucking air downward through the wind box 7 for 20 to 45 minutes, and the mixed raw material filled with this combustion heat is sintered to obtain a sintered cake To do.

着火から焼結ケーキ製造までの過程で蒸発した水分は充填層下部で凝集して湿潤層を形成するが、原料の微粉はもみ殻に入り込み、擬似粒子の物理的強度が向上しているので、擬似粒子の崩壊は起こらず通気を阻害しない。すなわち、充填層の通気が確保され、焼結鉱の生産能率が向上する。 The moisture evaporated in the process from ignition to sintered cake production aggregates in the lower part of the packed bed to form a wet layer, but the raw powder enters the rice husk and the physical strength of the pseudo particles is improved, Pseudoparticles do not collapse and do not hinder aeration. That is, ventilation of the packed bed is ensured, and the production efficiency of the sintered ore is improved.

また、焼結反応に対し、少なくとも９００℃以上（最高１２５０〜１３００℃）の高温の状態が２〜４分間維持される間に、もみ殻は容易に燃焼消失するので焼結反応を阻害することはない。また、もみ殻の燃焼熱が有効利用できるので固体燃料を節減することができる。 In addition, the rice husk easily burns and disappears while the high temperature state of at least 900 ° C. or higher (maximum 1250 to 1300 ° C.) is maintained for 2 to 4 minutes. There is no. Moreover, since the combustion heat of rice husk can be used effectively, solid fuel can be saved.

もみ殻の装入量は、あまり少なすぎては効果が十分得られず、逆に多すぎると焼結鉱製造コストが高くなりすぎることに加え、もみ殻中には、Ｚｎ、Ｃｌ、Ｎａ、Ｋ等低融点化合物を生成する成分が含有されているため、高炉内で付着物を形成する等の問題が生じるので、焼結用混合原料１００質量％（乾量基準）に対して、もみ殻装入量は、０．０１〜２質量％とするのが望ましい。 If the amount of rice husk is too small, the effect is not sufficiently obtained. On the other hand, if the amount is too large, the production cost of the sinter becomes too high. In the rice husk, Zn, Cl, Na, Since components that produce low melting point compounds such as K are contained, problems such as the formation of deposits in the blast furnace arise, so the rice husk is 100% by mass (based on dry weight) of the mixed raw material for sintering. The charging amount is desirably 0.01 to 2% by mass.

本発明の効果を確認するため、以下の実験を実施した。
まず、表１に示す成分よりなり、表２に示す粒度の鉄鉱石Ａ、Ｂ、Ｃ、Ｄと焼結返鉱などその他の原料を表３の配合比で配合した。 In order to confirm the effect of the present invention, the following experiment was conducted.
First, other raw materials such as iron ores A, B, C, and D having the particle sizes shown in Table 2 and sintered ore were mixed at the mixing ratio shown in Table 3.

次に、この鉄鉱石粉にコークス粉３．５質量％と定法の通りに石灰石と適量の水を配合した焼結用原料を、１次ミキサーにて撹拌混合した。その後、混合原料を２次ミキサーに移し、該ミキサーにもみ殻を０．３５質量％装入して撹拌混合した。 Next, a raw material for sintering in which this iron ore powder was blended with 3.5% by mass of coke powder and limestone and an appropriate amount of water as usual was stirred and mixed with a primary mixer. Thereafter, the mixed raw material was transferred to a secondary mixer, and 0.35% by mass of rice husk was charged into the mixer, followed by stirring and mixing.

造粒効果を確認するために、サンプリングを実施し、以下の式（１）で定義される、造粒の評価指標ＧＩと、焼結中の通気性を評価するために、以下の式（２）で定義される、通気性指数ＪＰＵを求めた。結果を以下の表４に示す。なお、造粒の評価指標ＧＩは、大きいほど、微粉の放出が少なく擬似粒子径が大きく優れていることを示し、通気指数ＪＰＵは、大きいほど通気性が良好なことを示している。 In order to confirm the granulation effect, sampling is performed, and in order to evaluate the granulation evaluation index GI defined by the following formula (1) and the air permeability during sintering, the following formula (2 The air permeability index JPU defined by The results are shown in Table 4 below. Note that the larger the granulation evaluation index GI, the smaller the emission of fine powder and the greater the pseudo particle size, and the better the air permeability index JPU, the better the air permeability.

ＧＩ＝（（１−A´／A）＋（１−B´／B））×１００・・・（１）
ここにA：粒径０．２５〜０．５ｍｍの擬似粒子化前の重量％、A´：粒径０．２５〜０．５ｍｍの擬似粒子化後の重量％、B：粒径０．２５ｍｍ以下の擬似粒子化前の重量％、B´：粒径０．２５ｍｍ以下の擬似粒子化後の重量％、
ＪＰＵ＝（Ｆ／Ａ）×（ｈ／（ｓ／９．８０６６５））＾０．６・・・（２）
ここに、Ｆ：吸引ガス流量（ｍ^３（標準状態）／ｍｉｎ）、Ａ：充填層断面積（ｍ^２）、ｈ：充填層高さ（ｍ）、ｓ：吸引圧力（ｋＰａ） GI = ((1-A ′ / A) + (1-B ′ / B)) × 100 (1)
Here, A:% by weight before quasi-particle formation with a particle size of 0.25 to 0.5 mm, A ′:% by weight after quasi-particle formation with a particle size of 0.25 to 0.5 mm, B: particle size of 0.25 mm % By weight before pseudo-particle formation, B ′: weight% after pseudo-particle formation with a particle size of 0.25 mm or less,
JPU = (F / A) × (h / (s / 9.80665)) ^ 0.6 (2)
Here, F: suction gas flow rate (m ³ (standard state) / min), A: packed bed cross-sectional area (m ² ), h: packed bed height (m), s: suction pressure (kPa)

比較例
もみ殻を装入しない以外は実施例と同じ原料を用い、実施例と同じ条件で撹拌混合して前記ＧＩと通気性指数ＪＰＵを求めた。結果を以下の表４に示す。 Comparative Example The same raw material as in the example was used except that rice husk was not charged, and the mixture was stirred and mixed under the same conditions as in the example to obtain the GI and air permeability index JPU. The results are shown in Table 4 below.

表４より明らかのように、従来例に比べ、もみ殻を装入した本発明の方が、造粒指数ＧＩが５．６上昇、通気性指数ＪＰＵも２．６上昇し、擬似粒子化後の焼結用原料の粒度の増大とそれに伴う通気の改善について確認された。 As is clear from Table 4, the granule index GI increased by 5.6 and the air permeability index JPU increased by 2.6 in the present invention in which rice husk was charged, compared with the conventional example, and after the pseudo-particle formation The increase in the grain size of the raw material for sintering and the improvement of the air flow associated therewith were confirmed.

本実施例によると、以上のように、１次焼結造粒ミキサーと２次焼結造粒ミキサー間にて、もみ殻を０．３５重量％装入することにより、従来例より擬似粒子化後の焼結用原料の粒度の増大と、焼結中の通気の改善することができた。 According to the present example, as described above, by adding 0.35% by weight of rice husk between the primary sintering granulation mixer and the secondary sintering granulation mixer, pseudo particles are formed compared to the conventional example. It was possible to increase the particle size of the raw material for subsequent sintering and to improve the air flow during sintering.

焼結の該略図。The schematic of sintering.

符号の説明Explanation of symbols

１・・原料槽
２・・１次ミキサー
３・・２次ミキサー
４・・ドワイトロイド式焼結機
５・・パレット
６・・点火炉
７・・ウィンドボックス
８・・セットリングチャンバー 1. Raw material tank 2. Primary mixer 3. Secondary mixer 4. Dwelloid type sintering machine 5. Pallet 6. Ignition furnace 7. Wind box 8. Settling chamber

Claims

鉄鉱石粉、焼結返鉱、副原料、固体燃料その他を配合した焼結原料を撹拌混合により造粒する工程の途中で、開口部を備えた空隙を有する有底物質を装入し、当該有底物質の空隙内に焼結原料の微粉を取り込むことを特徴とする焼結原料の造粒方法。 During the process of granulating the sintered raw material containing iron ore powder, sintered ore, auxiliary raw material, solid fuel, etc. by agitation and mixing, a bottomed material having a void with an opening is charged and the A method for granulating a sintering raw material, comprising incorporating fine powder of the sintering raw material into voids in the bottom material.

前記有底物質の装入量は、０．０１〜２質量％とすることを特徴とする請求項１記載の焼結原料の造粒方法。 The method for granulating a sintering raw material according to claim 1, wherein the charged amount of the bottomed substance is 0.01 to 2% by mass.

前記有底物質が、もみ殻であることを特徴とする請求項１又は２記載の焼結原料の造粒方法。 The method for granulating a sintering raw material according to claim 1 or 2, wherein the bottomed material is rice husk.