【発明の詳細な説明】[Detailed description of the invention]
〔産業上の利用分野〕
本発明はキツシユグラフアイト又はスラグ中よ
り分離した、粗粒銑から鉄粉末を製造する方法に
関するものである。
〔従来技術〕
高炉溶銑処理作業中、不可避的に発生するキツ
シユ黒鉛を含む不定形粗粒銑は溶銑量の約１％内
外発生し、その量は多大である。しかし、一部は
磁選されて付加価値の低いスクラツプとなるほ
か、焼結用原料等としてリサイクルされるのが実
状である。ところが、粗粒銑は粒形２mm以下のも
のが約50％を占め、鉄粉原料として注目されてい
る。しかしながら粒状で且つ可成りのじん性をも
つているため破砕時の衝撃荷重が分散し、通常の
破砕機であるボールミル、ハンマーミルその他の
機械的破砕では破砕困難な欠点をもつている。こ
のような破砕しにくい固体金属の粉砕法として化
学工業便覧（丸善株式会社）P.1031−17、３、６
に記載されているような低温粉砕法がある。低温
粉砕は砕料が常温では熱可塑性、或は強じん性を
有する場合にドライアイスや液体窒素等の冷媒で
冷却し、脆性を与えて粉砕する方法のため、鉄類
を粉砕する場合、ドラムやボール材の低温脆性を
配慮して特殊材料を用いなければならない。又嵩
張る鉄系スクラツプは特開昭52−52482（金属スク
ラツプ処理方法）のように常温で軽くプレスした
後、冷却したスクラツプを圧潰し、粗破砕の後、
微粉砕する方法もあるが、常温での機械的粉砕法
よりランニングコストや設備費が大きいことが知
られている。
一方、機械的粉砕法に(1)ボールミル法、(2)ハン
マーミル法、(3)振動ミル法、(4)スタンプミル法、
(5)エツジミル法、(6)マイクロナイザー法等知られ
ているが、(4)〜(6)は設備費が大きく、又粉砕能率
も比較的低く、(1)〜(3)で粉砕することが最も経済
的である。しかしながら、該粗粒銑は前述したよ
うに形状と材質の両面から粉砕時の衝撃荷重が分
散し、ボールミル法においては長時間粉砕しても
粉化率が低い。しかも粉砕機構は磨耗作用による
粗粒銑表面のみ粉化し、衝撃による体積粉砕が行
われない。又ハンマーミル法においては予めエツ
ジミルで粗破砕したものでもスクリーンの磨耗が
著しく、スクリーン交換のため粉砕機の運転時間
が短く10分以内の断続稼動となり作業性が悪く生
産設備として得策でない。
振動ミルにおいては、巾広い粒度構成をもつ該
粗粒銑を分別し３mm以下の細粒は実験室規模の振
動ミルで微粉砕は可能であるが３mm以上の粗粒銑
は粗破砕を行わなければ粉砕できず、その鉄粉末
は凹凸の少ない球形を呈し、焼結金属用並にカイ
ロ用原料としては不適で、且つ実生産規模のミル
は現在のところ見当らない。
〔発明が解決しようとする問題点〕
前記溶銑処理中に発生する長径15mm以下で不特
定形状の粗粒銑は、その粒度構成成は第３図イに
示すように２mm以下の細粒が多いにもかかわら
ず、常温での機械的粉砕法では材質の両面から微
粉砕することは困難である。即ち、該粗粒銑は粒
状でしかも銑鉄と同材質であることから靭性を有
するため、破砕時の衝撃荷重が分散し、その粉砕
機構は粗粒銑の表面層が僅に磨耗粉砕するだけで
なので体積粉砕が進行する手段が必要である。
〔問題点を解決する手段〕
粗粒銑の材質は銑鉄と同種であることから靭性
を有し４％程度の黒鉛を含有する。又その形状例
（３〜10mm）は第６図に示すように不特定粒状を
示す。しかも細粒と混合しているため破砕時の衝
撃荷重が分散し粉砕しにくいことは前記に示した
通りである。しかし、該粗粒銑は低応力で黒鉛を
起点として亀裂が発生し易い性質がある。しかも
常温で低速圧潰することによつて含有黒鉛を起点
として無数の亀裂を発生させ得る。
本発明はこの点に着目して開発したもので、そ
の製造方法は高炉溶銑の出銑及び鋳銑等の溶銑処
理時に発生するキツシユグラフアイトとスラグの
混合物中から分離した粗粒銑を予め常温で圧潰し
板状に塑性変形することにより多数の亀裂を発生
させ、その後微粉砕することを特徴とする鉄粉末
の製造方法である。
本発明の製造工程について説明すると先ずキツ
シユグラフアイトから粗粒銑を分離する工程があ
り、高炉から出銑された溶銑を鋳銑機、又は混銑
炉へ搬送し、それぞれの場所で発生するキツシユ
グラフアイトと溶滓の混合物を排滓し留置する。
留置した排滓をバースクリーン（篩分）で分級す
る。
次にトロンメンによりスラツジ、小塊、荒銑、
粗粒銑に分離する。上記の分離方法は乾式でも可
能である。また、前記の粗粒銑は出銑、鋳銑及び
転炉以外から発生したものも含む。
次に分離した粗粒銑を多段ロールによつて複数
のロールを通して圧潰し１mm程度の板状に塑性変
形させ、多数の亀裂を発生させる。その後、微粉
砕機で微粉砕する。
〔作用〕
まず粗粒銑を分離する方法を実施例にもとずい
て説明する。該粗粒銑はキツシユグラフアイトや
排滓中に混在しており、分離しなければならな
い。第２図はその分離方法を示す。高炉Ａより出
銑された溶銑は溶銑鍋Ｂに受けられ鋳銑機Ｃ又は
混銑炉Ｄに送られ、夫々の溶銑処理時に排滓Ｅ，
Ｆが行なわれる。この排滓には多量の荒銑や粒銑
が混在するため、鉄源及びグラフアイトの回収を
行なう。排滓物は一時留置され、その後バースク
リーンＨの300ｍ／ｍ篩目で分級される。＋300
ｍ／ｍは篩上荒銑Ｉとなり−300ｍ／ｍは篩下荒
鉄、グラフアイト、スラツジとなる。その後−
300ｍ／ｍは水洗、篩分のを有するトロンメンＫ
によつてまずスラツジを除去し、その他は−15
ｍ／ｍの粗粒銑Ｎと15〜300ｍ／ｍの小塊荒銑Ｍ
となる。上記のうち、粗粒銑Ｎは以下に説明する
ような装置で微粉砕される。
第１図は粗粒銑を圧潰微粉砕するための装置例
である。該装置は粗粒銑貯蔵ホツパー１、シユー
ト２、多段ロール５、磁選装置を有するコンベア
ー８及び微粉砕機１０等からなる。該ホツパー１
とシユート２の間には必要のつど切出させるゲー
ト３がある。又該多段ロール５は複数のロール６
及びガイド７からなつており、該ロール５は上段
から下段に進むにつれてその間隙が狭くなつてい
る。その後の工程には夾雑物除去のため磁選装置
を有するコンベアー８及びホツパー９を介して微
粉砕機１０が設けられている。
上記微粉砕機はボールミル、ハンマーミル、振
動ミル等いずれでも可能である。好ましくは得ら
れる鉄粉粒形及び粉砕能率の良い振動ミルがよ
い。
本発明では、粗粒銑の粉砕困難な主因である粒
状形を低速回転ロールで常温圧潰することにより
第７図のように無数の亀裂を発生させた板状に塑
性変形させられるため、その後の微粉砕を容易に
する。又この塑性変形方法はロール又はプレスに
よつて可能であるが、プレス圧潰は材料供給が断
続的になるため生産性が悪く、大量処理には不適
であるがロールによる圧潰は連続的に材料供給が
可能なことから大量処理に適する。ロールは粒状
の原料を噛み込ませるためと粒形の大きいものは
パス回数を多くして所定の厚さに圧潰させるため
垂直多段型が好ましい。
前記の方法によつて１mm程度に圧潰した板状砕
料は大粒形程ロールパス回数が多くなるため発生
亀裂の伝播によつて砕断分割されるものもあり、
該粗粒銑の１mm以上の粒径のものは無数の亀裂を
発生した砕料に変化する。かくして得られた砕料
は粉砕時の衝撃荷重を分散させることなく、しか
も同時生成した亀裂の相乗効果から体積粉砕が著
しく向上するため、粗破砕工程を省略して微粉砕
することが可能になる。
特に圧潰時の亀裂発生による体積粉砕により凹
凸の著しい形状となり、焼結金属用並にカイロ用
原料が適した鉄粉末が得られる。
上記鉄粉末は使途に応じて分級し粒度をそろえ
て混合し最適粒度にすると良く、例えば市販され
ている鉄粉カイロ用と同程度の品質を保証するこ
とができる。
鉄粉末を製造する作用の実施例を以下に説明す
る。
第１図に示したように、該粗粒銑を貯蔵するホ
ツパー１に取付けられたシユート２よりロール長
さ40cmの約70％にわたり圧潰されるように巾広く
該粗粒銑４を２Kg／分の切出しで落下させ周速10
ｍ／分以下の低速回転する垂直多段ロール５の上
段ロール６（ロール間のすき間６ｍ／ｍ）で50％
の圧下率で圧潰ガイド７を通り、さらに中段ロー
ル（ロール間のすき間2.5ｍ／ｍ）で60％、下段
ロール（ロール間のすき間１ｍ／ｍ）で60％圧下
で夫々圧潰し約１mmの板状にした。
この圧潰工程は下段ロールの間隙より小さい該
粗粒銑は無圧下で通過するが各段ロール間隙より
大きい該粗粒銑は圧潰されロールパス回数の多い
もの程黒鉛を起点とした亀裂の伝播により分割さ
れる。圧潰用ロールの材質は該粗粒銑が白銑化し
ていないためHRB 140以下で軟く圧潰時、砕料
がロールへ張付がないチルドロールがよい。圧潰
された砕料は磁選装置を有するコンベアー８によ
りホツパー９に貯蔵され、微粉砕機１０に供給さ
れる。圧潰した砕料をドラム径30cmドラム長さ20
cmのボールミルに10Kg装入し回転数50rpmで１時
間粉砕した。粉砕後の粒度構成は第３図のロのよ
うになり無圧潰でボールミル粉砕７時間の粒度構
成第３図ハ及び無圧潰の該粗粒銑10Kgをハンマー
クラツシヤーで15分粗破砕の後アトマイザーで所
要時間50分微粉砕した粒度構成ニに比較して最も
破砕率が良い。
又、本発明による方法で粉砕した鉄粉末を149
〜297μで分級した粒形は第８図のように長方多
角形となつており、焼結金属及びカイロ用原料と
して理想的な形状になつている。この鉄粉末を−
297〜149μと−149μに分級し、市販品同様に各々
50％の割合で混合し発熱テストを実施した結果第
４図に示すように市販の使い捨てカイロの発熱温
度並に発熱持続時間等、同等の特性を有すること
が確認された。
又、本発明で粉砕された鉄粉末を297μ以下で
分別し焼結金属用鉄粉として可否を試験した結
果、第１表に示す粒度構成のものが得られ、バイ
ンダー無添加で成型した。この鉄粉末には前記の
ように３〜４％の黒鉛を含むためバインダーの添
加を必要とせず且つ3t／cm2低加圧でも抜型後のハ
ンドリングも支障なく成型性に優れている。
[Industrial Application Field] The present invention relates to a method for producing iron powder from coarse-grained pig iron separated from wood graphite or slag. [Prior Art] During blast furnace hot metal processing operations, amorphous coarse particles containing hard graphite are unavoidably generated, accounting for approximately 1% of the amount of hot metal, and the amount thereof is large. However, some of it is magnetically separated into scrap with low added value, and in reality, it is recycled as raw material for sintering. However, approximately 50% of coarse-grained pig iron has a grain size of 2 mm or less, and is attracting attention as a raw material for iron powder. However, since it is granular and has considerable toughness, it has the disadvantage that the impact load during crushing is dispersed, making it difficult to crush by mechanical crushing such as ball mills, hammer mills, and other conventional crushers. Chemical Industry Handbook (Maruzen Co., Ltd.) P.1031-17, 3, 6 as a method of crushing solid metals that are difficult to crush.
There is a cryogenic grinding method as described in . Cryogenic pulverization is a method in which pulverized material, which is thermoplastic or tough at room temperature, is cooled with a refrigerant such as dry ice or liquid nitrogen to make it brittle and then pulverized. Special materials must be used in consideration of the low-temperature brittleness of the ball material. In addition, bulky iron-based scraps are lightly pressed at room temperature as in JP-A-52-52482 (metal scrap processing method), then the cooled scraps are crushed, and after rough crushing,
There is also a method of finely pulverizing, but it is known that running costs and equipment costs are higher than mechanical pulverization at room temperature. On the other hand, mechanical crushing methods include (1) ball mill method, (2) hammer mill method, (3) vibration mill method, (4) stamp mill method,
(5) Edgemill method, (6) Micronizer method, etc. are known, but (4) to (6) require high equipment costs and have relatively low pulverization efficiency. This is the most economical option. However, as described above, the impact load during crushing of the coarse pig iron is dispersed due to both its shape and material, and in the ball mill method, the pulverization rate is low even if it is crushed for a long time. Furthermore, the crushing mechanism only pulverizes the surface of the coarse particles due to wear, and volumetric crushing due to impact is not performed. In addition, in the hammer mill method, even if the material is coarsely crushed in advance using an edge mill, the screen wears out significantly, and the operation time of the crusher is short and requires intermittent operation of less than 10 minutes to replace the screen, resulting in poor workability and is not a good idea as a production facility. In a vibratory mill, the coarse pig iron with a wide particle size composition is separated, and fine grains of 3 mm or less can be pulverized using a laboratory-scale vibration mill, but coarse pig pigs of 3 mm or more must be coarsely crushed. The iron powder cannot be pulverized, and the iron powder has a spherical shape with few irregularities, making it unsuitable as a raw material for sintered metals or body warmers, and no commercial-scale mill has been found at present. [Problems to be solved by the invention] The coarse-grained pig iron with a long diameter of 15 mm or less and an unspecified shape generated during the hot metal treatment has a particle size composition that is mostly fine particles of 2 mm or less, as shown in Figure 3 A. Nevertheless, it is difficult to pulverize the material from both sides using mechanical pulverization at room temperature. In other words, since the coarse-grained pig is granular and made of the same material as pig iron, it has toughness, so the impact load during crushing is dispersed, and the crushing mechanism is such that the surface layer of the coarse-grained pig is only slightly abraded and crushed. Therefore, a means for volumetric pulverization is required. [Means for solving the problem] Since the material of coarse-grain pig is the same as pig iron, it has toughness and contains about 4% graphite. Further, an example of the shape (3 to 10 mm) shows an unspecified grain shape as shown in FIG. Moreover, as described above, since it is mixed with fine particles, the impact load during crushing is dispersed, making it difficult to crush. However, the coarse-grained pig iron has a property of being prone to cracking starting from graphite due to low stress. Moreover, by crushing at room temperature and at low speed, countless cracks can be generated starting from the graphite contained. The present invention was developed focusing on this point, and the manufacturing method is based on the method of producing coarse pig iron separated from a mixture of graphite and slag that is generated during tapping of blast furnace hot metal and processing of hot metal such as casting pig iron. This is a method for producing iron powder, which is characterized by generating a large number of cracks by crushing and plastically deforming it into a plate shape at room temperature, and then pulverizing it into fine particles. To explain the manufacturing process of the present invention, there is first a step of separating coarse grained pig iron from wood graphite, and the hot metal tapped from the blast furnace is transported to an iron casting machine or a mixer furnace, and the molten pig iron generated at each location is The mixture of tsushigraphite and slag is drained and retained.
The retained waste slag is classified using a bar screen. Next, trommen produced sludge, small lumps, rough pig iron,
Separate into coarse pig iron. The above separation method can also be performed dryly. Further, the above-mentioned coarse-grained pig iron includes those generated from sources other than tap iron, cast pig iron, and converter furnaces. Next, the separated coarse-grained pig iron is crushed through a plurality of rolls to be plastically deformed into a plate shape of about 1 mm, and a large number of cracks are generated. Then, it is pulverized using a pulverizer. [Operation] First, a method for separating coarse-grained pig iron will be explained based on an example. The coarse pig iron is mixed in the wood graphite and slag and must be separated. Figure 2 shows the separation method. The hot metal tapped from the blast furnace A is received in the hot metal ladle B and sent to the pig iron casting machine C or the pig iron mixer D. During each hot metal treatment, the slag E,
F is performed. Since this slag contains a large amount of rough pig iron and granular pig iron, the iron source and graphite will be recovered. The waste is temporarily stored and then classified using a bar screen H with a 300m/m sieve mesh. +300
m/m is rough iron above the sieve I, and -300 m/m is rough iron below the sieve, graphite, and sludge. After that-
300m/m is Trommen K with water washing and sieving.
First remove the sludge by
m/m coarse pig iron N and 15 to 300 m/m small lump pig iron M
becomes. Among the above, coarse pig pig N is finely pulverized using a device as described below. FIG. 1 shows an example of an apparatus for crushing and pulverizing coarse pig iron. The apparatus consists of a coarse pig iron storage hopper 1, a chute 2, a multistage roll 5, a conveyor 8 having a magnetic separator, a pulverizer 10, etc. The hopper 1
There is a gate 3 between the chute 2 and the chute 2, which is cut out whenever necessary. Further, the multistage roll 5 includes a plurality of rolls 6
and a guide 7, and the gap between the rolls 5 becomes narrower as it progresses from the upper stage to the lower stage. In the subsequent process, a pulverizer 10 is provided via a hopper 9 and a conveyor 8 equipped with a magnetic separator to remove impurities. The above-mentioned pulverizer may be a ball mill, a hammer mill, a vibration mill, or the like. Preferably, a vibrating mill is used because of its obtainable iron powder particle shape and grinding efficiency. In the present invention, the granular shape, which is the main reason why coarse-grained pig iron is difficult to crush, is crushed by low-speed rotating rolls at room temperature, so that it is plastically deformed into a plate shape with countless cracks as shown in Figure 7. Facilitates fine grinding. Also, this plastic deformation method is possible using rolls or a press, but press crushing has poor productivity because the material supply is intermittent, and is unsuitable for mass processing. It is suitable for mass processing because it is possible to It is preferable that the roll be of the vertical multi-stage type in order to bite the granular raw material and to crush the large granular material to a predetermined thickness by increasing the number of passes. The plate-shaped crushed material crushed to about 1 mm by the above method may be broken into pieces due to the propagation of cracks, as the larger the particle size, the greater the number of roll passes.
The coarse pig iron with a particle size of 1 mm or more turns into crushed material with numerous cracks. The thus obtained crushed material does not disperse the impact load during crushing, and the volumetric crushing is significantly improved due to the synergistic effect of the simultaneously generated cracks, so it becomes possible to omit the coarse crushing step and perform fine crushing. . In particular, the volume pulverization due to cracking during crushing results in a significantly uneven shape, and iron powder is obtained that is suitable as a raw material for sintered metals and body warmers. The above-mentioned iron powder may be classified according to the purpose of use, and the particle size may be made uniform and mixed to obtain the optimum particle size. For example, it is possible to guarantee the same quality as that for commercially available iron powder body warmers. An example of the operation of producing iron powder will be described below. As shown in Fig. 1, the coarse-grained pig iron 4 is rolled at 2 kg/min so as to be crushed over approximately 70% of the roll length of 40 cm from the chute 2 attached to the hopper 1 that stores the coarse-grained piglet. Cut it out and drop it at a circumferential speed of 10
50% with upper roll 6 of vertical multistage roll 5 (gap between rolls 6m/m) rotating at low speed of m/min or less
The plate passes through the crushing guide 7 at a rolling reduction rate of , and is further crushed by the middle roll (gap between rolls 2.5 m/m) at a reduction of 60% and the lower roll (gap between rolls 1 m/m) at a reduction of 60%, respectively, to a thickness of approximately 1 mm. It was made into a shape. In this crushing process, the coarse pig iron, which is smaller than the gap between the lower rolls, passes under no pressure, but the coarse pig iron, which is larger than the gap between each corrugated roll, is crushed. be done. The material of the crushing roll is preferably a chilled roll, which has an HRB of 140 or less and is soft so that the crushed material does not stick to the roll during crushing because the coarse grained pig iron is not whitened. The crushed material is stored in a hopper 9 by a conveyor 8 having a magnetic separator, and is supplied to a pulverizer 10. The crushed material is transferred to a drum with a diameter of 30 cm and a length of 20 cm.
10 kg of the material was charged into a cm ball mill and pulverized at a rotation speed of 50 rpm for 1 hour. The particle size composition after crushing is as shown in Figure 3 B. The particle size composition after 7 hours of ball mill crushing without crushing is shown in Figure 3 C. After crushing 10 kg of the coarse pig without crushing for 15 minutes with a hammer crusher. The crushing rate is the best compared to particle size configuration 2, which was finely pulverized using an atomizer for 50 minutes. In addition, iron powder pulverized by the method according to the present invention is 149
The particle shape classified by ~297μ is a rectangular polygon as shown in Figure 8, which is an ideal shape as a raw material for sintered metals and body warmers. This iron powder-
Classified into 297-149μ and -149μ, each as well as commercially available products.
As shown in Figure 4, the mixture was mixed at a ratio of 50% and a heat generation test was conducted. As shown in Figure 4, it was confirmed that the heat generation temperature and duration of heat generation were equivalent to those of commercially available disposable body warmers. Further, as a result of classifying the iron powder pulverized according to the present invention into particles of 297 μm or less and testing whether they can be used as iron powder for sintered metals, particles having the particle size configuration shown in Table 1 were obtained and molded without the addition of a binder. Since this iron powder contains 3 to 4% graphite as described above, it does not require the addition of a binder and has excellent moldability with no trouble in handling after demolding even at a low pressure of 3 t/cm 2 .
〔発明の効果〕〔Effect of the invention〕
このように従来スクラツプとして回収されてい
た粗粒銑の材質特性からロール又はプレスによつ
て圧潰し、多数の亀裂を発生させることによつて
破砕困難な粗粒銑を低コストで粉砕を可能にし
た。又、その品質を焼結金属用並にカイロ用原料
に適した鉄粉末としたことにより数倍の付加価値
増が図られるばかりでなく、近年需要増から不足
している鉄粉カイロ用原料として安価に供給で
き、経済効果は顕著である。
In this way, due to the material properties of coarse-grained pig that was conventionally recovered as scrap, it is possible to crush coarse-grained pig that is difficult to crush at low cost by crushing it with rolls or presses and generating many cracks. did. In addition, by making the iron powder suitable for use as a raw material for body warmers as well as for sintered metals, we not only increase added value several times, but also as a raw material for iron powder body warmers, which has been in short supply due to increased demand in recent years. It can be supplied at low cost and has significant economic effects.
【図面の簡単な説明】[Brief explanation of the drawing]
第１図は本発明の鉄粉末製造方法を示すフロ
ー、第２図はキツシユグラフアイトから粗粒銑を
分離するフロー、第３図は破砕前粗粒銑の粒度分
布と各種破砕法によつて得られた鉄粉末の粒度分
布、(イ)破砕前粗粒銑の粒度分布、(ロ)本発明による
破砕後の粒度分布、(ハ)無圧潰粗粒銑をボールミル
で７時間破砕した粒度分布、(ニ)無圧潰粗粒銑をハ
ンマークラツシヤーで15分粗破砕の後アトマイザ
ーで50分微粉砕した粒度分布、第４図は本発明で
得られた鉄粉末をカイロ用原料としての適否を試
験した発熱試験結果を示す。第５図は本発明で得
られた鉄粉末で40φ試料を成型し圧粉体密度を測
定したものである。(1)ダライ粉を粉砕した鋳鉄粉
の圧粉体密度、(2)本発明による鉄粉末の圧粉体密
度、第６図は破砕前粗粒銑（３〜10mm）の外観
例、第７図は第６図をロールで圧潰した亀裂発生
状況の外観例、第８図は本発明で得られた鉄粉末
粒形例、
１：粗粒銑貯蔵ホツパー、２：同シユート、
３：ゲート、４：粗粒銑、５：多段ロール、６：
ロール、７：ガイド、８：コンベアー、９：圧潰
後の砕料貯蔵ホツパー、１０：微粉砕機、Ａ：高
炉、Ｂ：溶銑鍋、Ｃ：鋳銑機、Ｄ：混銑炉、Ｅ：
排滓、Ｆ：排滓、Ｇ：留置、Ｈ：バースクリーン
（篩分）、Ｉ：篩上荒銑、Ｊ：篩下荒銑、Ｋ：トロ
ンメン（水洗、篩分）、Ｌ：スラツジ、Ｍ：小塊
荒銑、Ｎ：粗粒銑。
Figure 1 shows the flow of the method for producing iron powder of the present invention, Figure 2 shows the flow of separating coarse grain pig from wood graphite, and Figure 3 shows the particle size distribution of coarse grain pig before crushing and various crushing methods. (a) Particle size distribution of coarse pig iron before crushing, (b) Particle size distribution after crushing according to the present invention, (c) Particle size of non-crushed coarse pig iron crushed for 7 hours in a ball mill. (d) Particle size distribution obtained by crushing non-crushed coarse pig iron for 15 minutes with a hammer crusher and then finely pulverizing it with an atomizer for 50 minutes. The results of the heat generation test for compliance are shown. FIG. 5 shows the green compact density measured by molding a 40φ sample using the iron powder obtained according to the present invention. (1) Green density of cast iron powder obtained by crushing dull powder, (2) Green density of iron powder according to the present invention, Fig. 6 is an example of the appearance of coarse-grained pig iron (3 to 10 mm) before crushing, Fig. 7 The figure shows an example of the appearance of cracks generated by crushing Fig. 6 with a roll, and Fig. 8 shows an example of the iron powder particle shape obtained by the present invention. 1: Coarse grain pig storage hopper, 2: Same chute
3: Gate, 4: Coarse grain pig iron, 5: Multistage roll, 6:
Roll, 7: Guide, 8: Conveyor, 9: Crushed material storage hopper after crushing, 10: Pulverizer, A: Blast furnace, B: Hot metal pot, C: Pig iron casting machine, D: Mixing iron furnace, E:
Slag, F: Slag, G: Detention, H: Bar screen (sieve), I: Rough pig on the sieve, J: Rough pig on the bottom of the sieve, K: Trommen (washing with water, sieving), L: Sludge, M : Small lump rough pig iron, N: Coarse grain pig iron.