JP2007211302A - Finish heat treatment method for iron powder and finish heat treatment device - Google Patents

Finish heat treatment method for iron powder and finish heat treatment device Download PDF

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JP2007211302A
JP2007211302A JP2006033295A JP2006033295A JP2007211302A JP 2007211302 A JP2007211302 A JP 2007211302A JP 2006033295 A JP2006033295 A JP 2006033295A JP 2006033295 A JP2006033295 A JP 2006033295A JP 2007211302 A JP2007211302 A JP 2007211302A
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iron powder
heat treatment
gas
hopper
furnace
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JP4839869B2 (en
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Yasuhiko Sakaguchi
泰彦 阪口
Satoshi Uenosono
聡 上ノ薗
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JFE Steel Corp
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<P>PROBLEM TO BE SOLVED: To provide an advantageous finish heat treatment method for iron powder for improving production efficiency in the finish heat treatment stage of iron powder production, and to provide a finish heat treatment device used for the treatment. <P>SOLUTION: In the finish heat treatment method for iron powder where raw material iron powder dischargaed from a hopper for iron powder storage is preheated in the stage of the discharge, is thereafter continuously fed into a finish heat treatment furnace, and is subjected one or more treatments selected from deoxidizing, decarburizing and denitriding, a gas for heating is blown from the lower part of the hopper so as to preheat the raw material iron powder. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、鉄粉の仕上熱処理方法および仕上熱処理装置に関し、特に、粗仕上した原料鉄粉に、脱炭、脱酸および脱窒のいずれか１種以上の処理を施して鉄粉を製造する仕上熱処理方法とその処理に用いられる仕上熱処理装置に関するものである。   The present invention relates to a finish heat treatment method and a finish heat treatment apparatus for iron powder, and in particular, the iron powder is produced by subjecting the roughly finished raw iron powder to at least one of decarburization, deoxidation, and denitrification. The present invention relates to a finish heat treatment method and a finish heat treatment apparatus used for the treatment.

鉄粉は、粉末冶金で製造される焼結部品や磁性材料等の原料として、あるいは鉄粉のままで、脱酸素剤や発熱剤等として、幅広い分野で用いられている。この鉄粉は、ミルスケール等の酸化鉄を粗還元した還元鉄粉やアトマイズしたままの噴霧鉄粉等の粗仕上（粗還元）した原料鉄粉を、要求特性や用途に応じて、脱炭、脱酸および脱窒のいずれか１種または２種以上の仕上熱処理を施して製品（鉄粉）とするのが一般的である（例えば、特許文献１参照）。   Iron powder is used in a wide range of fields as a raw material for sintered parts and magnetic materials manufactured by powder metallurgy, or as an oxygen scavenger and a heat generating agent as it is. This iron powder can be used to decarburize raw iron powder that has been coarsely reduced (roughly reduced), such as reduced iron powder obtained by rough reduction of iron oxide such as mill scale, or atomized atomized iron powder, depending on required characteristics and applications. In general, one or two or more finish heat treatments of deoxidation and denitrification are performed to obtain a product (iron powder) (for example, see Patent Document 1).

上記仕上熱処理は、原料鉄粉を、ホッパから移動床と呼ばれる連続的に移動するベルト（移動床）上に供給して一定の厚さに積層し、その後、この移動床を、温度および雰囲気ガスが制御された仕上熱処理炉（水平炉あるいは連続式移動床炉ともいう）内に連続的に送り込んで通過させることにより行われる。   In the finishing heat treatment, the raw iron powder is supplied from a hopper onto a continuously moving belt (moving bed) called a moving bed and laminated to a certain thickness. Is performed by continuously feeding and passing through a controlled finishing heat treatment furnace (also called a horizontal furnace or a continuous moving bed furnace).

図４は、従来の仕上熱処理装置を側面から見た時の断面図を示したものである。原料鉄粉７は、ホッパ８から移動床９上に一定の厚さとなるよう供給され、その後、上記移動床９上の原料鉄粉７は、ホイール１０を駆動して移動床９を仕上熱処理炉３０内に炉長方向に移動することによって連続的に炉内に送入され、所定の仕上熱処理を施されたのち炉外に搬出される。   FIG. 4 shows a cross-sectional view of a conventional finish heat treatment apparatus viewed from the side. The raw iron powder 7 is supplied from the hopper 8 onto the moving floor 9 so as to have a certain thickness, and thereafter, the raw iron powder 7 on the moving floor 9 drives the wheel 10 to finish the moving bed 9 in a finishing heat treatment furnace. By moving in the furnace length direction into the furnace 30, it is continuously fed into the furnace, and after being subjected to a predetermined finishing heat treatment, it is carried out of the furnace.

炉内は、ラジアントチューブ１１によって所定温度に加熱されており、ラジアントチューブ１１内の燃焼ガスは、燃焼ガス排気管１２を通じて炉外に排出され、排気ダクト１４へ送られる。また、炉内の雰囲気ガスは、炉出口側の雰囲気ガス供給口５から炉内に供給され、炉入口側の雰囲気ガス排出口６から炉外に排出され、その後、燃焼させられた後、雰囲気ガス排気管１３を介して排気ダクト１４へ送られる。   The inside of the furnace is heated to a predetermined temperature by the radiant tube 11, and the combustion gas in the radiant tube 11 is discharged out of the furnace through the combustion gas exhaust pipe 12 and sent to the exhaust duct 14. The atmosphere gas in the furnace is supplied into the furnace from the atmosphere gas supply port 5 on the furnace outlet side, discharged from the atmosphere gas discharge port 6 on the furnace inlet side to the outside of the furnace, and then burned, It is sent to the exhaust duct 14 via the gas exhaust pipe 13.

移動床９上の原料鉄粉７は、炉内を連続的に通過中に、雰囲気ガス中に含まれる水蒸気ないしは水素と、下記（１）〜（３）式に従って反応し、脱炭、脱酸ないしは脱窒のいずれか１以上の処理が行われる。
Ｃ（ｉｎ Ｆｅ）＋Ｈ２Ｏ（ｇ） → ＣＯ（ｇ）＋Ｈ２（ｇ） ・・・（１）
ＦｅＯ（ｓ）＋Ｈ２（ｇ） → Ｆｅ（ｓ）＋Ｈ２Ｏ（ｇ） ・・・（２）
Ｎ（ｉｎ Ｆｅ）＋３／２Ｈ２（ｇ） → ＮＨ３（ｇ） ・・・（３） The raw iron powder 7 on the moving bed 9 reacts with water vapor or hydrogen contained in the atmospheric gas while continuously passing through the furnace in accordance with the following formulas (1) to (3) to decarburize and deoxidize. One or more treatments of denitrification or denitrification are performed.
C (in Fe) + H 2 O (g) → CO (g) + H 2 (g) (1)
FeO (s) + H 2 (g) → Fe (s) + H 2 O (g) (2)
N (in Fe) + 3 / 2H 2 (g) → NH 3 (g) (3)

これらの反応には、それぞれに最適の条件があり、例えば、脱炭反応は、温度が６００〜１１００℃で露点が３０〜６０℃の酸化性ガス雰囲気が、脱酸反応は、温度が７００〜１１００℃で露点が４０℃以下の還元ガス雰囲気が、脱窒反応は、温度が４５０〜７５０℃で露点が４０℃以下のＨ２ガス雰囲気が最適とされている。そのため、仕上熱処理炉の炉内は、長手方向に入口側から第一室２、第二室３、第三室４の三室に区分され、それぞれの室間に仕切り壁１が配設された構造となっており、例えば、第一室２では脱炭反応、第二室３では脱酸反応、第三室４では脱窒反応が主に起こるように、各室の温度および雰囲気ガスが制御されているのが一般的である。 Each of these reactions has optimum conditions. For example, a decarburization reaction has an oxidizing gas atmosphere at a temperature of 600 to 1100 ° C. and a dew point of 30 to 60 ° C., and a deoxidation reaction has a temperature of 700 to 700 ° C. The reducing gas atmosphere having a dew point of 40 ° C. or lower at 1100 ° C. is optimal for the denitrification reaction, and the H 2 gas atmosphere having a temperature of 450 to 750 ° C. and a dew point of 40 ° C. or lower is optimal. Therefore, the furnace of the finish heat treatment furnace is divided into three chambers of the first chamber 2, the second chamber 3, and the third chamber 4 from the inlet side in the longitudinal direction, and the partition wall 1 is disposed between the chambers. For example, the temperature and atmospheric gas in each chamber are controlled so that the decarburization reaction occurs mainly in the first chamber 2, the deoxidation reaction occurs in the second chamber 3, and the denitrification reaction occurs mainly in the third chamber 4. It is common.

ところで、仕上熱処理装置で、効率よく仕上熱処理を行うためには、炉内の各室に装入された鉄粉が、早期に上記最適温度に到達することが必要である。しかし、原料鉄粉７を、室温状態から加熱した場合には、第一室２内を移動する原料鉄粉７層の中心部が所定の温度に到達するのは、同室の出口付近となる。そのため、原料鉄粉の昇温が律速となって、移動床９の移動速度を上げたり、原料鉄粉７の積層厚さを厚くしたりして、生産性の向上を図ることは難しい。   By the way, in order to efficiently perform the finish heat treatment with the finish heat treatment apparatus, it is necessary that the iron powder charged in each chamber in the furnace reach the optimum temperature at an early stage. However, when the raw iron powder 7 is heated from room temperature, the central portion of the raw iron powder 7 layer moving in the first chamber 2 reaches a predetermined temperature near the outlet of the same chamber. Therefore, it is difficult to improve productivity by increasing the temperature of the raw iron powder, thereby increasing the moving speed of the moving bed 9 or increasing the thickness of the raw iron powder 7.

そこで、仕上熱処理工程における生産性を向上するために、第一室に入る前の原料鉄粉を予熱し、第一室の入口通過時の鉄粉温度を高くしておく方法が提案されている。例えば、特許文献２には、図４に示したように、仕上熱処理炉の燃焼排ガスを排気ダクトによって予熱器１５に導入して原料鉄粉７を予熱することによって、原料鉄粉７の炉内搬送速度を高める技術が開示されている。   Therefore, in order to improve productivity in the finish heat treatment process, a method of preheating the raw iron powder before entering the first chamber and increasing the iron powder temperature when passing through the entrance of the first chamber has been proposed. . For example, in Patent Document 2, as shown in FIG. 4, by introducing the combustion exhaust gas of the finishing heat treatment furnace into the preheater 15 through the exhaust duct and preheating the raw iron powder 7, A technique for increasing the conveyance speed is disclosed.

また、特許文献３には、上記技術において、原料鉄粉７の予熱に用いられる熱交換器（予熱器１５）が開示されている（図５参照）。ここで、上記予熱器１５は、ホッパ８下部の鉄粉の移動通路と排気ダクト１４とを交叉させると共に、該交叉部の排気ダクト１４を複数の熱交換用パイプ１６に分岐させた多管式とし、この管内に仕上熱処理炉の燃焼排ガスを流すことにより、ホッパ８から出た原料鉄粉７を該交叉部内の熱交換用パイプ１６間を通り抜ける際に間接加熱するものである。なお、予熱の熱源として用いられる排気ダクト１４内を流れる燃焼排ガスは、ラジアントチューブ１１内で燃焼したガスを炉外に排出したガス（燃焼ガス）と、炉内で鉄粉と反応させた雰囲気ガスを炉外で燃焼させたガス（反応排ガス）の混合ガスである。   Further, Patent Document 3 discloses a heat exchanger (preheater 15) used for preheating the raw iron powder 7 in the above technique (see FIG. 5). Here, the preheater 15 crosses the iron powder moving passage below the hopper 8 and the exhaust duct 14, and also has a multi-tube type in which the exhaust duct 14 at the crossing portion is branched into a plurality of heat exchange pipes 16. Then, by flowing the flue gas from the finishing heat treatment furnace into the pipe, the raw iron powder 7 discharged from the hopper 8 is indirectly heated when passing through between the heat exchange pipes 16 in the intersection. Note that the combustion exhaust gas flowing in the exhaust duct 14 used as a heat source for preheating is a gas (combustion gas) obtained by exhausting the gas combusted in the radiant tube 11 to the outside of the furnace, and an atmospheric gas that is reacted with iron powder in the furnace. Is a mixed gas of gas (reaction exhaust gas) burned outside the furnace.

一方、特許文献４には、図６および図７に示したように、原料鉄粉７を直接加熱する予熱方法が提案されている。具体的には、原料鉄粉７を貯蔵されたホッパ８から移動床９へ供給するときに、原料鉄粉７へ気体供給管１８から加熱された高温の非酸化性気体（加熱用気体５２）を直接吹き込み、その反対側に設けられた気体排出管１９から該気体を排出する。このとき、高温の非酸化性気体５２と原料鉄粉７との間で熱交換が行われ、予熱された原料鉄粉７が移動床９上に供給される。
特開昭５２−１５６７１４号公報 特開昭６２−２３５４０１号公報 特開昭６３−１５３２０４号公報 特開２００６−００９１３８号公報 On the other hand, as shown in FIGS. 6 and 7, Patent Document 4 proposes a preheating method for directly heating the raw iron powder 7. Specifically, when supplying the raw iron powder 7 from the stored hopper 8 to the moving bed 9, the high-temperature non-oxidizing gas (heating gas 52) heated from the gas supply pipe 18 to the raw iron powder 7 Is directly blown, and the gas is discharged from a gas discharge pipe 19 provided on the opposite side. At this time, heat exchange is performed between the high-temperature non-oxidizing gas 52 and the raw iron powder 7, and the preheated raw iron powder 7 is supplied onto the moving bed 9.
JP-A-52-156714 Japanese Patent Laid-Open No. 62-235401 JP-A-63-153204 JP 2006-009138 A

上記特許文献３に開示の予熱方法によれば、原料鉄粉は、内側に燃焼排ガスが流れている熱交換用パイプの外面と接触して間接加熱されるので、酸化や固着を起こすことなく移動床上に積層することができる。しかし、上記予熱器では、逆に熱交換用パイプを介して燃焼排ガスから原料鉄粉に熱が移動するため、熱交換用パイプの周囲の原料鉄粉にしか熱が伝わらないことや熱交換用パイプの熱伝導率が熱移動の抵抗として働くため、熱交換効率が低いという問題がある。また、原料鉄粉が熱交換用パイプの間を移動するため、パイプが該鉄粉により摩耗を受けて穴があくという問題や、原料鉄粉自体が熱交換用パイプと接触することで摩耗して球状化し、鉄粉の圧粉密度の低下を招くので、粉末冶金に使われる高密度材には適さなくなるという問題があった。   According to the preheating method disclosed in Patent Document 3, the raw iron powder is indirectly heated in contact with the outer surface of the heat exchange pipe through which the combustion exhaust gas flows, so that it moves without causing oxidation or sticking. Can be laminated on the floor. However, in the above preheater, the heat is transferred from the combustion exhaust gas to the raw iron powder via the heat exchange pipe, so that the heat is transferred only to the raw iron powder around the heat exchange pipe or for heat exchange. Since the heat conductivity of the pipe acts as a resistance to heat transfer, there is a problem that the heat exchange efficiency is low. In addition, since the raw iron powder moves between the heat exchange pipes, the pipe is worn by the iron powder, and the raw iron powder itself is worn by contact with the heat exchange pipe. As a result, the iron powder becomes spheroidized and the powder density of the iron powder is reduced, which makes it unsuitable for high-density materials used in powder metallurgy.

また、特許文献４に記載の方法では、ホッパ内の原料鉄粉７の量が減少してホッパレベルが低下した場合には、気体供給管１８から吹き込まれた加熱用気体５２は、気体排出管１９には流れずに、ホッパ８側へ流れ込んでしまう。そのため、気体供給管１８の気体供給口近傍の原料鉄粉しか予熱されないという問題があった。   Further, in the method described in Patent Document 4, when the amount of the raw iron powder 7 in the hopper is reduced and the hopper level is lowered, the heating gas 52 blown from the gas supply pipe 18 is supplied to the gas discharge pipe. It does not flow into 19 but flows into the hopper 8 side. Therefore, there is a problem that only the raw iron powder in the vicinity of the gas supply port of the gas supply pipe 18 is preheated.

そこで、本発明の目的は、鉄粉製造の仕上熱処理工程における生産効率を向上させることができる鉄粉の有利な仕上熱処理方法とその処理に用いる仕上熱処理装置を提供することにある。   Accordingly, an object of the present invention is to provide an advantageous finish heat treatment method for iron powder that can improve the production efficiency in the finish heat treatment step of iron powder production and a finish heat treatment apparatus used for the treatment.

発明者らは、従来技術が抱える上記問題点を解決する方策について検討を重ねた。その結果、鉄粉貯蔵用ホッパから排出される原料鉄粉を、その排出の段階で予備加熱するに際して、前記ホッパ下部の傾斜部から、高温でかつ非酸化性の加熱用気体を吹き込んで、原料鉄粉と直接接触させることが有効であることを見出し、還元鉄粉の製造方法である本発明を完成させた。   Inventors repeated examination about the policy which solves the above-mentioned problem which conventional technology has. As a result, when preheating the raw iron powder discharged from the iron powder storage hopper at the discharge stage, a high-temperature non-oxidizing heating gas is blown from the inclined portion at the lower part of the hopper, It was found that direct contact with iron powder was effective, and the present invention, which is a method for producing reduced iron powder, was completed.

すなわち、本発明は、鉄粉貯蔵用ホッパから排出される原料鉄粉を、その排出の段階で予備加熱し、その後、仕上熱処理炉内に連続的に供給して脱酸、脱炭および脱窒のいずれか１以上の処理を施す鉄粉の仕上熱処理方法において、前記ホッパ下部から加熱用気体を吹き込んで原料鉄粉を予熱することを特徴とする鉄粉の仕上熱処理方法である。   That is, the present invention preheats raw iron powder discharged from an iron powder storage hopper at the discharge stage, and then continuously supplies it into a finishing heat treatment furnace for deoxidation, decarburization and denitrification. In the iron powder finish heat treatment method for performing any one or more of the above processes, the raw iron powder is preheated by blowing a heating gas from the lower portion of the hopper.

本発明における上記加熱用気体は、２００℃以上でかつ２００℃における露点が２５℃以下の非酸化性ガスであることを特徴とする。   The heating gas in the present invention is a non-oxidizing gas having a dew point of 200 ° C. or higher and a dew point of 200 ° C. or lower.

また、本発明における上記加熱用気体は、水素ガス、窒素ガス、アルゴンガスおよびアンモニア分解ガスのうちのいずれか１種のガスまたは２種以上の混合ガスであることを特徴とする。   Further, the heating gas in the present invention is any one of hydrogen gas, nitrogen gas, argon gas, and ammonia decomposition gas, or a mixed gas of two or more.

また、本発明における上記加熱用気体は、仕上熱処理炉の燃焼排ガスで間接加熱したものであることを特徴とする。   The heating gas in the present invention is characterized in that it is indirectly heated with combustion exhaust gas from a finish heat treatment furnace.

また、本発明は、原料鉄粉を貯蔵するホッパと、原料鉄粉に脱酸、脱炭および脱窒のいずれか１以上の処理を施す仕上熱処理炉と、ホッパから排出された原料鉄粉を仕上熱処理炉内に送入する移動床とからなる鉄粉の仕上熱処理装置において、前記ホッパ下部に、加熱用気体供給部が設けられてなることを特徴とする鉄粉の仕上熱処理装置である。   The present invention also includes a hopper for storing raw iron powder, a finishing heat treatment furnace for subjecting the raw iron powder to at least one of deoxidation, decarburization, and denitrification, and raw iron powder discharged from the hopper. An iron powder finish heat treatment apparatus comprising a moving bed fed into a finish heat treatment furnace, wherein a heating gas supply unit is provided at a lower portion of the hopper.

本発明によれば、原料鉄粉を連続的に移動させつつ、これに脱炭、脱酸、脱室のうちのいずれか１種以上の処理を施す鉄粉の仕上熱処理において、前記処理を施す前（炉に入る前）に、原料鉄粉と高温非酸化性の加熱用気体とを直接接触させるので、原料鉄粉を酸化させることなく高い熱効率で、均等に予熱することができる。また、本発明によれば、炉に入る前の原料鉄粉の温度を従来よりも高くできるので、鉄粉が所定の処理温度に到達するまでの時間を短縮でき、ひいては、鉄粉の生産効率の向上だけでなく、燃料原単位を低減することが可能となる。また、本発明の仕上熱処理装置は、鉄粉の移動通路と交叉する熱交換用パイプがないので、その交換のための装置停止がなく、稼働率率が向上する。さらに、本発明の装置を用いて製造された鉄粉は、熱交換用パイプとの摩擦により球状化も起こらないので、高密度焼結部材の原料としても用いることが可能となる。   According to the present invention, in the finish heat treatment of iron powder, the raw iron powder is continuously moved and at least one of decarburization, deoxidation, and dechambering is performed. Since the raw iron powder and the high-temperature non-oxidizing heating gas are brought into direct contact before (before entering the furnace), the raw iron powder can be preheated uniformly with high thermal efficiency without being oxidized. Further, according to the present invention, since the temperature of the raw iron powder before entering the furnace can be made higher than before, it is possible to shorten the time until the iron powder reaches a predetermined processing temperature, and thus the iron powder production efficiency. In addition to improving the fuel consumption, it is possible to reduce the fuel consumption rate. In addition, since the finish heat treatment apparatus of the present invention does not have a heat exchange pipe that intersects with the iron powder moving passage, there is no stop of the apparatus for the exchange and the operating rate is improved. Furthermore, since the iron powder produced using the apparatus of the present invention does not spheroidize due to friction with the heat exchange pipe, it can be used as a raw material for a high-density sintered member.

本発明は、原料鉄粉を連続的に移動させつつ、これに脱炭、脱酸、脱窒のうちのいずれか１以上の処理を施す仕上熱処理に、従来技術と同様、水平型の仕上熱処理炉を用いるが、その際、ホッパ内に貯蔵されている仕上処理を施す直前の原料鉄粉に、該鉄粉よりも高温かつ非酸化性の気体を直接接触させるよう流して予熱を行うところに特徴がある。   In the present invention, as in the prior art, a horizontal finish heat treatment is applied to a finish heat treatment in which any one or more of decarburization, deoxidation, and denitrification is performed while continuously moving the raw iron powder. A furnace is used, but at that time, the raw iron powder stored in the hopper immediately before the finishing treatment is preheated by flowing a high-temperature and non-oxidizing gas directly into contact with the iron powder. There are features.

従来と同じ仕上熱処理炉を用いて原料鉄粉に仕上熱処理を施す場合には、ホッパに貯えられた原料鉄粉は、移動通路を順次下降して移動床に到達し、移動床上に所定の一定厚みとなるように積層される。原料鉄粉の予熱に用いられる加熱用気体は、ホッパ下部の傾斜部から送り込み、ホッパ上部から回収するのが好適である。本発明では、ホッパに貯えられた原料鉄粉内に加熱用気体を直接流し込むので、加熱用気体は、粉体の粒子間を流れるが、この際、粉体の表面積全体が熱伝導面となる。熱交換する熱量は、接触する表面積に比例するので、粉体粒子に加熱用気体を直接接触させる方が、変換効率は格段に向上し、高い効率で熱交換ができる。例えば、同じ体積を有する直径１０ｃｍの管と直径１００μｍの粉体とでは、管内の空隙率を５０ｖｏｌ％とすると、表面積は粉体の方が約７５０倍大きくなる。   When finishing heat treatment is applied to the raw iron powder using the same finishing heat treatment furnace as before, the raw iron powder stored in the hopper descends down the moving passage sequentially to the moving bed, and reaches a predetermined constant on the moving bed. It is laminated so as to have a thickness. The heating gas used for preheating the raw iron powder is preferably sent from an inclined portion at the lower part of the hopper and recovered from the upper part of the hopper. In the present invention, since the heating gas is directly flowed into the raw iron powder stored in the hopper, the heating gas flows between the particles of the powder. At this time, the entire surface area of the powder becomes the heat conduction surface. . Since the amount of heat to be exchanged is proportional to the surface area to be contacted, the direct conversion of the heating gas to the powder particles improves the conversion efficiency and enables high-efficiency heat exchange. For example, with a 10 cm diameter tube having the same volume and a 100 μm diameter powder, the surface area of the powder is about 750 times larger when the porosity in the tube is 50 vol%.

加熱用気体の温度は、原料鉄粉より高い温度であれば、鉄粉温度を上昇させることができる。しかし、仕上熱処理での投入熱量の低減や装入鉄粉量の増加による生産性の向上が期待できるような実質的な効果を得るためには、加熱用気体の温度は２００℃以上であることが好ましい。ただし、前述したように、脱炭、脱酸、脱窒等の化学反応には、それぞれに最適の温度があるので、熱処理炉の最初の第一室で行う処理に好適な温度以上に鉄粉を予熱する必要はなく、第一室で行う処理に応じて、加熱用気体の温度を適宜設定するのが好ましい。   If the temperature of the heating gas is higher than the raw iron powder, the iron powder temperature can be increased. However, the temperature of the heating gas should be 200 ° C. or higher in order to obtain a substantial effect that can be expected to improve productivity by reducing the amount of heat input in finishing heat treatment or increasing the amount of charged iron powder. Is preferred. However, as described above, since there are optimum temperatures for chemical reactions such as decarburization, deoxidation, and denitrification, iron powder exceeds the temperature suitable for the treatment performed in the first first chamber of the heat treatment furnace. It is not necessary to preheat the gas, and it is preferable to appropriately set the temperature of the heating gas according to the treatment performed in the first chamber.

ただし、高温の気体を直接原料鉄粉に接触させて予熱する場合、かかる高温の気体は、非酸化性の気体、すなわち、その温度で鉄を酸化させない気体でなければならない。さらに、説明すると、前述した（２）式；
ＦｅＯ（ｓ）＋Ｈ２（ｇ） → Ｆｅ（ｓ）＋Ｈ２Ｏ（ｇ） ・・・（２）
の化学反応は、２００℃では露点２５℃以上、５００℃では露点５５℃以上で、反応が右から左に進み、鉄粉が酸化される。 However, when preheating is performed by bringing a high-temperature gas into direct contact with the raw iron powder, the high-temperature gas must be a non-oxidizing gas, that is, a gas that does not oxidize iron at that temperature. Further, the above-described formula (2);
FeO (s) + H 2 (g) → Fe (s) + H 2 O (g) (2)
The chemical reaction of 200 ° C. has a dew point of 25 ° C. or higher, and 500 ° C. has a dew point of 55 ° C. or higher. The reaction proceeds from right to left, and iron powder is oxidized.

そこで、本発明では、非酸化性の気体として、酸素を含まずかつ露点が２５℃以下であるという条件を満たす気体を用いることが好ましい。かかる非酸化性の気体としては、例えば、水素ガス、窒素ガス、アルゴンガス、アンモニア分解ガス（ＡＸガス）およびそれらのガスを１種または２種以上混合したガス等を挙げることができる。   Therefore, in the present invention, it is preferable to use a gas that does not contain oxygen and satisfies the condition that the dew point is 25 ° C. or lower as the non-oxidizing gas. Examples of the non-oxidizing gas include hydrogen gas, nitrogen gas, argon gas, ammonia decomposition gas (AX gas), and a gas obtained by mixing one or more of these gases.

なお、非酸化性の気体としては、上記条件を満たすものであればいずれの気体を用いてもよく、例えば、可燃性ガスを不完全燃焼させたガスを用いてもよい。また、仕上熱処理の反応排ガスは、主に水素ガスと水蒸気の混合ガスであるため、原料鉄粉中の炭素濃度が低い（例えば０．５ｍａｓｓ％以下）場合には、脱炭のために添加する水蒸気の量が少ないので露点が２５℃以下となり、温度も約９００℃で排出されるため、高温かつ非酸化性気体として利用することができる。   As the non-oxidizing gas, any gas may be used as long as it satisfies the above conditions. For example, a gas obtained by incompletely combusting a combustible gas may be used. Further, since the reaction exhaust gas of the finish heat treatment is mainly a mixed gas of hydrogen gas and water vapor, it is added for decarburization when the carbon concentration in the raw iron powder is low (for example, 0.5 mass% or less). Since the amount of water vapor is small, the dew point is 25 ° C. or lower and the temperature is discharged at about 900 ° C., so that it can be used as a high-temperature and non-oxidizing gas.

非酸化性の気体を高温に加熱する方法としては、例えば、ボイラー等を用いる方法もあるが、仕上熱処理炉から排出される９００℃以上の燃焼排ガスと非酸化性の気体とを間接的に接触させて、燃焼排ガスの熱を非酸化性気体に与える、いわゆる熱交換させる方法が好ましく用いることができる。ただし、予熱後の原料鉄粉の温度は、高温ほど仕上熱処理工程の生産性が向上するが、６００℃以上にすると原料鉄粉が焼結し、流動性が低下して移動床への供給が困難となるので、予熱に用いる非酸化性気体の温度も上限を６００℃とするのが好ましい。   As a method of heating the non-oxidizing gas to a high temperature, for example, there is a method using a boiler or the like. However, the combustion exhaust gas of 900 ° C. or higher discharged from the finish heat treatment furnace and the non-oxidizing gas are contacted indirectly. Thus, a so-called heat exchange method in which the heat of the combustion exhaust gas is given to the non-oxidizing gas can be preferably used. However, the higher the temperature of the raw iron powder after preheating, the higher the productivity of the finish heat treatment process. However, if the temperature is 600 ° C. or higher, the raw iron powder sinters, the fluidity decreases and the supply to the moving bed is reduced. Since it becomes difficult, the upper limit of the temperature of the non-oxidizing gas used for preheating is preferably set to 600 ° C.

次に、本発明の仕上熱処理装置について図を用いて具体的に説明する。
図１は、一例として、本発明の仕上熱処理装置を側面から見た断面図を示したものである。同図において、１７は熱交換器、１８は気体供給管、１９は気体排出管、５０は反応排ガス、５１は非酸化性の気体（但し反応排ガスを除く）、５３は燃焼排ガスである。なお、図４と同一または相当部材には同じ符号を付した。図示したように、本発明の仕上熱処理装置は、仕上熱処理炉３０に入る直前の原料鉄粉７を予熱する装置として、ホッパ８下部の傾斜部からホッパ内に貯蔵している原料鉄粉中に加熱用気体（高温かつ非酸化性の気体）５２を吹き込む気体供給部とホッパ上部から予熱に使用後の加熱用気体を回収する気体排出部を有する。 Next, the finish heat treatment apparatus of the present invention will be specifically described with reference to the drawings.
FIG. 1 shows, as an example, a cross-sectional view of the finish heat treatment apparatus of the present invention as seen from the side. In the figure, 17 is a heat exchanger, 18 is a gas supply pipe, 19 is a gas exhaust pipe, 50 is a reaction exhaust gas, 51 is a non-oxidizing gas (excluding the reaction exhaust gas), and 53 is a combustion exhaust gas. In addition, the same code | symbol was attached | subjected to the same or equivalent member as FIG. As shown in the figure, the finish heat treatment apparatus of the present invention is a device for preheating the raw iron powder 7 immediately before entering the finish heat treatment furnace 30, into the raw iron powder stored in the hopper from the inclined portion at the bottom of the hopper 8. It has a gas supply part which blows in the heating gas (high temperature and non-oxidizing gas) 52 and a gas discharge part which collects the heating gas after use for preheating from the hopper upper part.

上記図１に示した仕上熱処理装置では、加熱用気体５２として、雰囲気ガス排気管１３を通って流れてくる反応排ガス５０に、外部から非酸化性気体５１を加え、これを熱交換器１７に通して燃焼排ガス５３と間接的に熱交換させ、高温としたものを用いている。   In the finishing heat treatment apparatus shown in FIG. 1, a non-oxidizing gas 51 is added from the outside to the reaction exhaust gas 50 flowing through the atmospheric gas exhaust pipe 13 as the heating gas 52, and this is supplied to the heat exchanger 17. The heat is indirectly exchanged with the combustion exhaust gas 53, and the temperature is increased.

また、図２は、本発明で用いる鉄粉を予熱する予熱器（ホッパ部分）を説明する図であり、気体供給部として気体供給管１８、気体排出部として気体排出管１９を設けた例を示している。なお、図１と同一または相当部材には同じ符号を付した。図２のように、本発明の予熱器（ホッパ部分）においては、加熱用気体５２は、気体供給管１８から原料鉄粉７が充填されたホッパ８内に吹き込まれ、該ホッパ内で原料鉄粉７と直接接触しながら原料鉄粉７に熱を与え、その後、ホッパ８上部に設置された気体排出管１９によって回収され、回収された気体は、仕上熱処理装置外に排出される。   Moreover, FIG. 2 is a figure explaining the preheater (hopper part) which preheats the iron powder used by this invention, The example which provided the gas supply pipe 18 as a gas supply part, and the gas discharge pipe 19 as a gas discharge part Show. Note that the same or corresponding members as those in FIG. As shown in FIG. 2, in the preheater (hopper portion) of the present invention, the heating gas 52 is blown from the gas supply pipe 18 into the hopper 8 filled with the raw iron powder 7, and the raw iron in the hopper. Heat is applied to the raw iron powder 7 in direct contact with the powder 7, and then recovered by the gas discharge pipe 19 installed on the upper portion of the hopper 8, and the recovered gas is discharged outside the finish heat treatment apparatus.

上記図２に示した予熱器（ホッパ部分）では、気体供給管１８をホッパ８下部の傾斜部に複数設置することにより、加熱用気体５２がホッパ８内の原料鉄粉７中を均等に流れて、鉄粉が均一予熱されるので、温度制御が容易となる。また、本発明例の予熱器（ホッパ部分）は、気体供給管１８の気体放出口にフィルタ２０を、気体排出管１９の気体回収口に集塵装置２１を配設しているので、鉄粉が気体供給管１８や気体排出管１９に侵入し難く、管詰りを有効に防止することができる。なお、フィルタや集塵装置の濾布としては、耐熱性の点から焼結金属あるいはセラミックスを用いることが好ましい。   In the preheater (hopper part) shown in FIG. 2 above, the gas 52 for heating flows evenly in the raw iron powder 7 in the hopper 8 by installing a plurality of gas supply pipes 18 on the inclined part below the hopper 8. Thus, since the iron powder is preheated uniformly, temperature control becomes easy. Further, in the preheater (hopper portion) of the present invention example, the filter 20 is disposed at the gas discharge port of the gas supply pipe 18 and the dust collector 21 is disposed at the gas recovery port of the gas discharge pipe 19. Does not easily enter the gas supply pipe 18 and the gas discharge pipe 19 and can effectively prevent clogging. In addition, as a filter cloth of a filter or a dust collector, it is preferable to use a sintered metal or ceramics from a heat resistant point.

表１に示した４種類の仕上熱処理装置（図４に示した装置から予熱器１５を取り除いた仕上熱処理装置、図４に示した仕上熱処理装置、図６に示した仕上熱処理装置および図１に示した仕上熱処理装置）を用いて、表１に示した条件で原料鉄粉の仕上熱処理を行い、原料鉄粉の温度の経時変化を測定すると共に、操業性を調査した。なお、原料鉄粉温度の経時変化は、移動床上の原料鉄粉層の厚さ中心位置に温度センサを設置し、炉内（第一室内）における原料鉄粉温度の時間による変化を測定した。   The four types of finish heat treatment apparatus shown in Table 1 (the finish heat treatment apparatus in which the preheater 15 is removed from the apparatus shown in FIG. 4, the finish heat treatment apparatus shown in FIG. 4, the finish heat treatment apparatus shown in FIG. Using the finishing heat treatment apparatus shown), the raw iron powder was subjected to a final heat treatment under the conditions shown in Table 1, the temperature change of the raw iron powder was measured over time, and the operability was investigated. In addition, the time-dependent change of raw material iron powder temperature installed the temperature sensor in the thickness center position of the raw material iron powder layer on a moving bed, and measured the change with time of the raw material iron powder temperature in a furnace (1st chamber).

Figure 2007211302
Figure 2007211302

図３は、原料鉄粉温度の経時変化を測定した結果を示したものである。
予熱器１５のない図４の仕上熱処理炉で処理したＮｏ．１（比較例１）では、原料鉄粉温度が、常温から２００℃まで昇温するのに７分、５００℃まで到達するのに１５分、炉内温度（９５０℃）まで到達するのに３０分を要している。その結果、炉内温度での保持時間は３０分であった。
また、図５に示した予熱器を有する図４の仕上熱処理炉で処理したＮｏ．２（比較例２）では、原料鉄粉は、炉に入る時には２００℃まで予熱されていたが、９５０℃まで到達するのに２８分を要しており、予熱しない場合（比較例１）と比較して大きな差はない。また、比較例２では、熱交換用パイプの摩耗による穴明きに起因したパイプ交換のためのダウンタイムが発生し、それによる停止が年間で１３回、延べで５８５分の停止時間が発生した。
また、同じく予熱器を有する図６の仕上熱処理炉で処理したＮｏ．３（比較例３）では、ホッパ内に貯蔵されている原料鉄粉量が低下したときに、加熱用気体５２が、気体排出管１９へ流れずにホッパ８側へ流れ込んでしまうため、均一な予熱が行えず、予熱を停止せざるを得ない状況が頻発し、その停止時間は平均して操業時間の６％強にも及んだため、操業が不安定となり、予熱の効果を十分に得ることができなかった。したがって、鉄粉温度の測定はできなかった。
これに対して、本発明の図１の仕上熱処理炉で処理したＮｏ．４（発明例）では、原料鉄粉がホッパ出側で４５０℃まで昇温されていたため、炉に入る際の鉄粉温度は３７０℃であり、炉内装入時から炉内温度（９５０℃）までは、比較例１と比較して８分短い、２２分で到達している。この結果から、鉄粉を炉内温度に保持する時間は、発明例でも比較例でも同じ（３０分）でよいから、本発明の熱処理装置を用いて比較例１と同じ熱処理を行う場合には、炉内通過時間を５２分に短縮でき、比較例１と比較して、１５％の生産性向上が図れることがわかった。また、本発明の仕上熱処理炉では、全操操業時間で予熱を行うことができ、上記比較例３で発生したような操業上のトラブルはなかった。 FIG. 3 shows the results of measuring the change over time in the raw iron powder temperature.
No. 1 processed in the finishing heat treatment furnace of FIG. 1 (Comparative Example 1), the raw iron powder temperature was 7 minutes for raising the temperature from room temperature to 200 ° C., 15 minutes for reaching 500 ° C., and 30 for reaching the furnace temperature (950 ° C.). It takes minutes. As a result, the holding time at the furnace temperature was 30 minutes.
Moreover, No. 1 processed in the finishing heat treatment furnace of FIG. 4 having the preheater shown in FIG. In 2 (Comparative Example 2), the raw iron powder was preheated to 200 ° C. when entering the furnace, but it took 28 minutes to reach 950 ° C., and when it was not preheated (Comparative Example 1). There is no big difference. Further, in Comparative Example 2, downtime for pipe replacement caused by drilling due to wear of the heat exchange pipe occurred, resulting in 13 stoppages per year, totaling 585 minutes stoppage time. .
In addition, No. 1 processed in the finishing heat treatment furnace of FIG. 3 (Comparative Example 3), when the amount of the raw iron powder stored in the hopper is reduced, the heating gas 52 flows into the hopper 8 side without flowing into the gas discharge pipe 19, so that it is uniform. There are frequent situations where preheating cannot be performed and preheating must be stopped, and the stop time has reached an average of more than 6% of the operation time, resulting in unstable operation and sufficient preheating effect. Couldn't get. Therefore, the iron powder temperature could not be measured.
On the other hand, No. 1 processed in the finishing heat treatment furnace of FIG. In No. 4 (Invention Example), since the raw iron powder was heated to 450 ° C. on the hopper exit side, the iron powder temperature when entering the furnace was 370 ° C., and the furnace temperature (950 ° C.) after entering the furnace interior Up to, it is 8 minutes shorter than that of Comparative Example 1, which is 22 minutes. From this result, since the time for holding the iron powder at the furnace temperature may be the same (30 minutes) in the invention example and the comparative example, when performing the same heat treatment as the comparative example 1 using the heat treatment apparatus of the present invention, It was found that the passage time in the furnace could be shortened to 52 minutes, and the productivity was improved by 15% as compared with Comparative Example 1. Moreover, in the finish heat treatment furnace of the present invention, preheating could be performed in the entire operation time, and there was no operational trouble that occurred in Comparative Example 3 above.

本発明の鉄粉製造技術は、粉末冶金や磁性材料などの原料として用いられる鉄粉や、化学反応用、カイロ用、脱酸素剤用等、粉末のままで用いられる鉄粉全てに好適に用いることができる。   The iron powder production technology of the present invention is suitably used for iron powder used as a raw material for powder metallurgy and magnetic materials, and for all iron powder used as a powder, such as for chemical reaction, for warmers, and for oxygen scavenger be able to.

本発明の仕上熱処理装置を説明する図である。It is a figure explaining the finishing heat processing apparatus of this invention. 本発明の仕上熱処理装置の予熱器（ホッパ部分）を説明する図である。It is a figure explaining the preheater (hopper part) of the finishing heat processing apparatus of this invention. 仕上熱処理装置内の鉄粉温度の経時変化を本発明の装置と従来の装置とで比較して示すグラフである。It is a graph which shows the time-dependent change of the iron powder temperature in a finishing heat processing apparatus with the apparatus of this invention, and the conventional apparatus. 従来の仕上熱処理装置の一例を説明する図である。It is a figure explaining an example of the conventional finishing heat processing apparatus. 従来の仕上熱処理装置の予熱器の一例を説明する図である。It is a figure explaining an example of the preheater of the conventional finishing heat processing apparatus. 従来の仕上熱処理装置の他の例を説明する図である。It is a figure explaining the other example of the conventional finishing heat processing apparatus. 従来の仕上熱処理装置の予熱器の他の例を説明する図である。It is a figure explaining the other example of the preheater of the conventional finishing heat processing apparatus.

符号の説明Explanation of symbols

１：仕切壁
２：第一室
３：第二室
４：第三室
５：雰囲気ガス供給口
６：雰囲気ガス排出口
７：原料鉄粉
８：ホッパ
９：移動床
１０：ホイール
１１：ラジアントチューブ
１２：燃焼ガス排気管
１３：雰囲気ガス排気管
１４：排気ダクト
１５：予熱器
１６：熱交換用パイプ
１７：熱交換器
１８：気体供給管
１９：気体排出管
２０：フィルタ
２１：集塵装置
３０：仕上熱処理炉
５０：反応排ガス
５１：非酸化性気体（反応排ガスを除く）
５２：加熱用気体（高温かつ非酸化性の気体）
５３：燃焼排ガス 1: Partition wall 2: First chamber 3: Second chamber 4: Third chamber 5: Atmospheric gas supply port 6: Atmospheric gas discharge port 7: Raw iron powder 8: Hopper 9: Moving floor 10: Wheel 11: Radiant tube 12: Combustion gas exhaust pipe 13: Atmospheric gas exhaust pipe 14: Exhaust duct 15: Preheater 16: Heat exchange pipe 17: Heat exchanger 18: Gas supply pipe 19: Gas exhaust pipe 20: Filter 21: Dust collector 30 : Finishing heat treatment furnace 50: Reaction exhaust gas 51: Non-oxidizing gas (excluding reaction exhaust gas)
52: Gas for heating (high temperature and non-oxidizing gas)
53: Combustion exhaust gas

Claims (5)

鉄粉貯蔵用ホッパから排出される原料鉄粉を、その排出の段階で予備加熱し、その後、仕上熱処理炉内に連続的に供給して脱酸、脱炭および脱窒のいずれか１以上の処理を施す鉄粉の仕上熱処理方法において、前記ホッパ下部から加熱用気体を吹き込んで原料鉄粉を予熱することを特徴とする鉄粉の仕上熱処理方法。 The raw iron powder discharged from the iron powder storage hopper is preheated at the discharge stage, and then continuously supplied into the finishing heat treatment furnace to be at least one of deoxidation, decarburization, and denitrification. A finishing heat treatment method for iron powder to be treated, characterized in that a heating gas is blown from the lower part of the hopper to preheat the raw iron powder. 上記加熱用気体は、２００℃以上でかつ２００℃における露点が２５℃以下の非酸化性ガスであることを特徴とする請求項１に記載の鉄粉の仕上熱処理方法。 The method for finishing heat treatment of iron powder according to claim 1, wherein the heating gas is a non-oxidizing gas having a dew point of 200 ° C or higher and a dew point of 200 ° C or lower. 上記加熱用気体は、水素ガス、窒素ガス、アルゴンガスおよびアンモニア分解ガスのうちのいずれか１種のガスまたは２種以上の混合ガスであることを特徴とする請求項１または２に記載の鉄粉の仕上熱処理方法。 3. The iron according to claim 1, wherein the heating gas is one of hydrogen gas, nitrogen gas, argon gas, and ammonia decomposition gas, or a mixed gas of two or more. Finish heat treatment method of powder. 上記加熱用気体は、仕上熱処理炉の燃焼排ガスで間接加熱したものであることを特徴とする請求項１〜３のいずれか１項に記載の鉄粉の仕上熱処理方法。 The iron powder finish heat treatment method according to any one of claims 1 to 3, wherein the heating gas is indirectly heated with combustion exhaust gas from a finish heat treatment furnace. 原料鉄粉を貯蔵するホッパと、原料鉄粉に脱酸、脱炭および脱窒のいずれか１以上の処理を施す仕上熱処理炉と、ホッパから排出された原料鉄粉を仕上熱処理炉内に送入する移動床とからなる鉄粉の仕上熱処理装置において、前記ホッパ下部に、加熱用気体供給部が設けられてなることを特徴とする鉄粉の仕上熱処理装置。 A hopper for storing the raw iron powder, a finishing heat treatment furnace for subjecting the raw iron powder to at least one of deoxidation, decarburization, and denitrification, and a raw iron powder discharged from the hopper to the finishing heat treatment furnace A finishing heat treatment apparatus for iron powder comprising a moving floor to enter, wherein a heating gas supply unit is provided in the lower part of the hopper, and the finishing heat treatment apparatus for iron powder.
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JP2010111933A (en) * 2008-11-10 2010-05-20 Taiyo Nippon Sanso Corp Method and apparatus for producing spherical metal particle
CN102689008A (en) * 2011-03-23 2012-09-26 杰富意钢铁株式会社 Method of finish heat treatment of iron powder and apparatus for finish heat treatment
WO2012127760A1 (en) * 2011-03-23 2012-09-27 Ｊｆｅスチール株式会社 Method of finish heat treatment of iron powder and apparatus for finish heat treatment
KR101532018B1 (en) * 2013-12-26 2015-06-26 주식회사 포스코 Iron powder, method and apparatus for manufacturing the same

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Publication number Priority date Publication date Assignee Title
JP2006009138A (en) * 2004-05-27 2006-01-12 Jfe Steel Kk Finish heat treatment method for iron powder and device therefor

Patent Citations (1)

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Publication number Priority date Publication date Assignee Title
JP2006009138A (en) * 2004-05-27 2006-01-12 Jfe Steel Kk Finish heat treatment method for iron powder and device therefor

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010111933A (en) * 2008-11-10 2010-05-20 Taiyo Nippon Sanso Corp Method and apparatus for producing spherical metal particle
CN102689008A (en) * 2011-03-23 2012-09-26 杰富意钢铁株式会社 Method of finish heat treatment of iron powder and apparatus for finish heat treatment
WO2012127760A1 (en) * 2011-03-23 2012-09-27 Ｊｆｅスチール株式会社 Method of finish heat treatment of iron powder and apparatus for finish heat treatment
JP2012211383A (en) * 2011-03-23 2012-11-01 Jfe Steel Corp Method and apparatus for finish heat treatment of iron powder
US9321103B2 (en) 2011-03-23 2016-04-26 Jfe Steel Corporation Finish heat treatment method and finish heat treatment apparatus for iron powder
US9815115B2 (en) 2011-03-23 2017-11-14 Jfe Steel Corporation Finish heat treatment method and finish heat treatment apparatus for iron powder
KR101532018B1 (en) * 2013-12-26 2015-06-26 주식회사 포스코 Iron powder, method and apparatus for manufacturing the same
WO2015099376A1 (en) * 2013-12-26 2015-07-02 주식회사 포스코 Iron particles, manufacturing method for same, and manufacturing device for same

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