JPH06116616A - Method and device for producing iron powder utilizing microwave - Google Patents

Method and device for producing iron powder utilizing microwave

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Publication number
JPH06116616A
JPH06116616A JP31769392A JP31769392A JPH06116616A JP H06116616 A JPH06116616 A JP H06116616A JP 31769392 A JP31769392 A JP 31769392A JP 31769392 A JP31769392 A JP 31769392A JP H06116616 A JPH06116616 A JP H06116616A
Authority
JP
Japan
Prior art keywords
microwave
heat
iron powder
carbonate
microwaves
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP31769392A
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Japanese (ja)
Other versions
JP3280435B2 (en
Inventor
Hitoshi Sakai
均 酒井
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Dowa Iron Powder Co Ltd
Original Assignee
Dowa Iron Powder Co Ltd
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Filing date
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Application filed by Dowa Iron Powder Co Ltd filed Critical Dowa Iron Powder Co Ltd
Priority to JP31769392A priority Critical patent/JP3280435B2/en
Publication of JPH06116616A publication Critical patent/JPH06116616A/en
Application granted granted Critical
Publication of JP3280435B2 publication Critical patent/JP3280435B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Abstract

PURPOSE:To produce a metallic iron powder in a short time with good energy efficiency by irradiating a mixture of the iron oxide powder, carbon source and carbonate with a microwave to internally heat the carbon source and to decompose the carbonate. CONSTITUTION:An iron oxide obtained by crushing iron ore, mill scale, etc., a carbon source such as coke and a carbonate such as calcium carbonate are mixed. The mixture is fed on the tray 36 of a conveyor C from a feeder 38 and transferred by a pusher 35 into the electric furnace 20 of a microwave heating and insulating electric furnace device B. The mixture is then irradiated with a microwave from a microwave transmitter A. As a result, the carbon source as a high microwave conductor is internally heated to >=900 deg.C, hence the carbonate is thermally decomposed, and the generated CO2 is reduced to CO. The iron oxide in the mixture is reduced by the CO into iron powder. The iron powder is cooled by a gaseous nitrogen in a microwave absorption chamber 28 and discharged from the furnace 20, and the generated metallic iron powder is refined by a magnetic separator 40.

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【産業上の利用分野】本発明は、COガスによる還元反
応により、鉄鉱石等の鉄酸化物を金属鉄にまで還元可能
な鉄酸化物の還元方法に関するもので、特に、被還元物
である粉砕した鉄酸化物と、固体の炭素源並びに熱分解
により容易に分解してCO2 ガスを発生する炭酸塩とを
混合し、この混合物にマイクロ波を照射して炭素源を内
部発熱させるとともに、炭酸塩の熱分解によって発生し
たCO2 ガスと接触させてCOガスに変換し、このCO
ガスによって炭熱反応(carbothermic反
応)によって鉄酸化物を金属鉄粉に到るまで還元して鉄
粉を製造する方法及び装置に関するものである。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reducing iron oxides capable of reducing iron oxides such as iron ore to metallic iron by a reduction reaction with CO gas, and more particularly to a substance to be reduced. The pulverized iron oxide, a solid carbon source, and a carbonate that is easily decomposed by thermal decomposition to generate CO 2 gas are mixed, and the mixture is irradiated with microwaves to internally heat the carbon source. It is converted into CO gas by contacting it with CO 2 gas generated by the thermal decomposition of carbonate.
The present invention relates to a method and an apparatus for producing iron powder by reducing iron oxides to metallic iron powder by a carbothermal reaction with gas.

【0002】本発明の特徴とする処は、第一に、金属酸
化物、特に、赤鉄鉱,磁鉄鉱,ミルスケール等の鉄酸化
物の金属鉄粉に到るまでの還元反応を短時間に、しか
も、容易に成就せしめ得ること、第二に、反応に必要と
するエネルギーをマイクロ波エネルギーによる炭素源の
内部発熱を利用して得ること、第三に、還元反応の開始
に必須であるCOを炭酸塩の熱分解によるCO2 にその
源を得たことである。
The feature of the present invention is that, firstly, a reduction reaction of a metal oxide, particularly an iron oxide of hematite, magnetite, mill scale, etc., to a metal iron powder is carried out in a short time, Moreover, it can be easily achieved, secondly, the energy required for the reaction can be obtained by utilizing the internal heat generation of the carbon source by the microwave energy, and thirdly, CO which is essential for the initiation of the reduction reaction can be obtained. That is, the source of CO 2 was obtained by thermal decomposition of carbonate.

【0003】[0003]

【従来の技術】一酸化炭素による鉄酸化物の還元反応は
工業的に広く用いられ、その例は鉄鉱石の溶鉱炉操業に
みられるとおりである。又、炭熱反応を利用する鉄粉製
造は、粉砕酸化鉄鉱石を原料とするスポンジ鉄粉の製造
方法として一般に行なわれている。しかし、これら従来
からの高炉製鉄法にしても、又、特に従来のスポンジ鉄
粉製造法にしても、鉄酸化物の還元のための熱源は、前
者では炭素源の空気中の酸素による酸化反応熱を利用す
ることで得ており、又、後者では炉の外部より加えられ
る熱の伝導によって炭素源を加熱して炭素の気化、即
ち、C+CO2 →2COで表される高い吸熱のブードア
反応(Boudouard反応)を進めることで得てい
る。
The reduction reaction of iron oxide with carbon monoxide is widely used industrially, and an example thereof is as found in the operation of a blast furnace for iron ore. Further, iron powder production utilizing a carbothermal reaction is generally carried out as a method for producing sponge iron powder using ground iron oxide ore as a raw material. However, even in these conventional blast furnace iron-making methods, and particularly in the conventional sponge iron powder manufacturing method, the heat source for the reduction of iron oxide is the oxidation reaction by oxygen in the air of the carbon source in the former case. It is obtained by utilizing heat, and in the latter case, the carbon source is heated by the conduction of heat applied from the outside of the furnace to vaporize carbon, that is, the highly endothermic Boudard reaction represented by C + CO 2 → 2CO ( It is obtained by advancing the Boudouard reaction).

【0004】この反応生成物であるCOが鉄酸化物と反
応し、Fe2 3 +3CO→2Fe+3CO2 の式に従
って鉄酸化物の還元が行なわれるが、同時に発生したC
2ガスが再び熱炭素源と反応してCOに還元される。
これが高い吸熱反応であるために、周囲より熱を奪って
自ずと炭素源の熱を下げる。そして、この熱を均衡させ
得るエネルギーは専ら外部加熱からの熱伝導による熱で
あるため、鉄酸化物の金属鉄への還元には膨大な熱エネ
ルギーと多大な反応時間を要することになり(例えば、
トンネルキルンでの操業では、炉にチャージするときか
らディスチャージするときまでに4日間も要する。)、
エネルギー効率の面からも、又、操業の能率の点からも
大きな問題であると言える。
The reaction product CO reacts with the iron oxide, and the iron oxide is reduced according to the formula Fe 2 O 3 + 3CO → 2Fe + 3CO 2 , but at the same time C is generated.
O 2 gas again reacts with the thermal carbon source and is reduced to CO.
Since this is a high endothermic reaction, it takes heat from the surroundings and naturally lowers the heat of the carbon source. Since the energy that can balance this heat is exclusively due to heat conduction from external heating, enormous heat energy and a great reaction time are required to reduce the iron oxide to metallic iron (for example, ,
In the tunnel kiln, it takes four days from the time of charging the furnace to the time of discharging it. ),
It can be said that this is a major problem in terms of energy efficiency and operational efficiency.

【0005】一方、マイクロ波をマイクロ波高誘導体に
照射すると、被照射物を効率良く内部発熱させることが
知られており、種々な分野で応用されている。工業的な
利用としては、ゴムの加硫、注射剤の滅菌、染色、木材
や茶葉の乾燥等があるが、いずれもせいぜい300℃程
度以下の加熱に利用されているにすぎない。このことか
ら言えば、マイクロ波高誘導体である炭素系材料を副原
料とする酸化鉱石の還元にもマイクロ波を利用すること
も考えられ、現に、特開昭64−52028号公報で
は、鉄鉱石と炭素系材料との混合物にマイクロ波を照射
する方法が開示されている。
On the other hand, it is known that when microwaves are applied to a microwave height derivative, an object to be irradiated is efficiently internally heated, and it is applied in various fields. Industrial applications include vulcanization of rubber, sterilization of injections, dyeing, and drying of wood and tea leaves, all of which are at best used for heating at about 300 ° C or lower. From this point of view, it may be possible to use microwaves for the reduction of oxide ores that use a carbonaceous material, which is a microwave high-derivative, as an auxiliary raw material. A method of irradiating a mixture with a carbon-based material with microwaves is disclosed.

【0006】[0006]

【発明が解決しようとする課題】しかしながら、この先
行例では、マイクロ波の照射は、赤鉄鉱から磁鉄鉱に到
るまでの還元過程での使用のみしか示されておらず、そ
れから先の金属鉄に到るまでの還元には言及されていな
い。僅かに、バス精錬炉の適用の可能性を示唆している
にすぎない。尚、後述の通り、赤鉄鉱はマイクロ波の高
誘導体とは言い得ないから、この段階でマイクロ波を照
射したとしても、赤鉄鉱の温度上昇にはあまり寄与しな
い。一方で、鉄酸化物の還元が効率的に行われるもう一
つ重要な要因は、反応系にCOガスの原料物質となるC
2 ガスが豊富に供給されることである。これを従来
は、鉄酸化物がCOガスによって還元されるときに生成
されるもののみに頼っていたから、せいぜい温度管理を
厳重に行い、反応を促進させるしか方法がなかった。従
って、反応速度には自ずから限界があった。
However, in this prior art example, the microwave irradiation is shown only for use in the reduction process from hematite to magnetite, and then to the above metallic iron. No mention is made of the reduction until the end. It only slightly suggests the possibility of applying a bath refining furnace. As will be described later, since hematite cannot be said to be a high-derivative of microwaves, even if microwaves are irradiated at this stage, it does not contribute much to the temperature rise of hematite. On the other hand, another important factor for efficient reduction of iron oxide is C, which is a raw material of CO gas in the reaction system.
O 2 gas is supplied abundantly. Heretofore, since only iron oxides produced when CO was reduced by CO gas were relied upon, the only method possible was to strictly control the temperature and accelerate the reaction. Therefore, the reaction rate was naturally limited.

【0007】本発明は、以上の課題を解決するものであ
って、要するに、900℃以上の温度の鉄酸化物から金
属鉄粉に到るまでの還元過程すべてに一貫してマイクロ
波を照射することと、この温度で容易にCO2 ガスに分
解する炭酸塩を副資材として添加するようにしたもので
ある。
The present invention solves the above problems and, in short, irradiates microwaves consistently throughout the reduction process from iron oxide at a temperature of 900 ° C. or higher to metallic iron powder. In addition, a carbonate which is easily decomposed into CO 2 gas at this temperature is added as an auxiliary material.

【0008】[0008]

【課題を解決するための手段】以上の課題の下、本発明
は、鉄鉱石、ミルスケール等の粉砕した鉄酸化物と、コ
ークス、チャー炭、活性炭、微粉炭等の炭素を主成分と
するマイクロ波高誘導体である炭素源と、炭酸カルシウ
ム、炭酸マグネシウム、炭酸ナトリウム等の炭酸塩とを
混合し、これら混合物にマイクロ波を照射して炭素源を
900℃を越えるまで内部発熱させるとともに、混合物
中の炭酸塩の熱分解によって発生したCO2 ガスと反応
させてCOガスに変換し、このCOガスによって鉄酸化
物を還元させて鉄粉を製造することを特徴とするマイク
ロ波を利用する鉄粉の製造方法を提供する。
Under the above problems, the present invention is mainly composed of crushed iron oxide such as iron ore and mill scale, and carbon such as coke, charcoal, activated carbon and pulverized coal. A carbon source which is a high microwave derivative is mixed with a carbonate such as calcium carbonate, magnesium carbonate or sodium carbonate, and the mixture is irradiated with microwaves to internally heat the carbon source until the temperature exceeds 900 ° C. Iron powder using microwaves, characterized in that it reacts with CO 2 gas generated by thermal decomposition of carbonate to convert it to CO gas, and reduces iron oxide by this CO gas to produce iron powder. A method for manufacturing the same is provided.

【0009】又、本発明は、前記した製造方法を実施す
る装置であって、この装置が、マイクロ波を発信するマ
イクロ波発信装置と、マイクロ波発信装置から発信され
たマイクロ波を導いて照射できるマイクロ波加熱室兼保
温用電気炉装置と、鉄酸化物、炭素源及び炭酸塩の混合
物を搭載してマイクロ波加熱室兼保温用電気炉装置内を
移動し、混合物にマイクロ波の照射を受けることができ
る移動装置とから構成されることを特徴とするマイクロ
波を利用する鉄粉の製造装置を提供する。
Further, the present invention is an apparatus for carrying out the above-mentioned manufacturing method, wherein the apparatus guides and irradiates a microwave transmitting device for transmitting a microwave and a microwave transmitted from the microwave transmitting device. A microwave heating chamber / heat-retaining electric furnace device and a mixture of an iron oxide, a carbon source and a carbonate can be mounted and moved in the microwave heating chamber / heat-retaining electric furnace device to irradiate the mixture with microwaves. Provided is an iron powder manufacturing apparatus utilizing microwaves, which is characterized in that it is configured with a moving device capable of receiving.

【0010】[0010]

【作用】従来から行われている鉄酸化物の炭素還元にお
いては、反応に必要とする熱の補給は専ら炭素源と鉄酸
化物との混合体の外部からの加熱に依存していたため
に、膨大な熱エネルギーと長時間にわたる反応時間を要
していたのに対し、本発明においては、従来、鉄酸化物
の還元のための源物質であるとされてきた炭素源をマイ
クロ波エネルギーの熱への転換物質として用いるため、
反応に必要なエネルギーを直接にマイクロ波から得られ
る点が特徴である。しかも、このマイクロ波エネルギー
は、マイクロ波高誘電物質においてのみ熱エネルギーに
転換され得るものであるから、従来法において用いられ
てきた炉体、炉壁、混合物の容器等の加熱物には何ら関
与せず、マイクロ波エネルギーは専ら反応に必要な炭素
源の加熱にのみ費やされることになる。
[Function] In the conventional carbon reduction of iron oxides, the replenishment of heat required for the reaction depends exclusively on the external heating of the mixture of the carbon source and the iron oxides. While enormous heat energy and long reaction time were required, in the present invention, a carbon source, which has been conventionally considered as a source material for reduction of iron oxide, is heated by microwave energy. To be used as a conversion material to
The feature is that the energy required for the reaction can be directly obtained from the microwave. Moreover, since this microwave energy can be converted into heat energy only in the microwave high-dielectric material, it should not be involved in the heating object such as the furnace body, furnace wall, and container of the mixture used in the conventional method. Instead, microwave energy will be dedicated exclusively to heating the carbon source needed for the reaction.

【0011】そして、この炭素源によって熱に変換され
たマイクロ波エネルギーの一部が炭素源と混在する鉄酸
化物と炭酸塩の加熱にも与えられる。このような加熱効
率の面から見ても、マイクロ波エネルギーを用いる鉄酸
化物の還元はエネルギー効率の高い方法であると言え
る。又、最近では、マイクロ波照射が加熱効果だけでな
く、化学反応において、活性化エネルギーを低下させ、
反応を促進する効果があることも報告されている。従っ
て、マイクロ波加熱は従来の加熱方法に比べて大きな省
エネにつながるし、反応時間を大幅に短縮することが可
能である。
Then, a part of the microwave energy converted into heat by the carbon source is also given to the heating of the iron oxide and carbonate mixed with the carbon source. From the viewpoint of such heating efficiency, it can be said that reduction of iron oxide using microwave energy is a highly energy efficient method. Also, recently, microwave irradiation not only has a heating effect, but also lowers activation energy in chemical reactions,
It is also reported to have an effect of promoting the reaction. Therefore, the microwave heating leads to great energy saving as compared with the conventional heating method, and the reaction time can be greatly shortened.

【0012】次に、この鉄酸化物、炭素源及び炭酸塩の
混合体にマイクロ波エネルギーを照射し続けることによ
り、得られる急速加熱によって反応時間が大幅に短縮さ
れることのみならず、鉄酸化物の還元は一気に金属鉄粉
の状態にまでに還元される。因みに、酸化鉄鉱石の代表
の一つである赤鉄鉱(Fe2 3 )は、マイクロ波エネ
ルギーに対しては低誘電体であって、それ単味では、マ
イクロ波照射によっては熱変換は極めて困難である。し
かし、この赤鉄鉱を900℃を超える加熱とCOの存在
で還元して得られる赤鉄鉱より更に酸素の少ない磁鉄鉱
(Fe3 4 )は、赤鉄鉱と違ってマイクロ波の高誘電
体である。
Next, by continuously irradiating the mixture of the iron oxide, the carbon source and the carbonate with microwave energy, not only the reaction time is greatly shortened by the rapid heating, but also the iron oxide is oxidized. The reduction of the substance is immediately reduced to the state of metallic iron powder. Incidentally, hematite (Fe 2 O 3 ), which is one of the representative iron oxide ores, has a low dielectric constant with respect to microwave energy, and by itself, heat conversion is extremely high depending on microwave irradiation. Have difficulty. However, the hematite to exceed 900 ° C. Heating and CO present in reduced low magnetite further oxygen than hematite obtained by the (Fe 3 O 4) is, is a high dielectric microwave unlike hematite .

【0013】従って、磁鉄鉱(天然産出の磁鉄鉱は勿
論、製鋼工程から得られるミルスケール等もこれに該当
する)はマイクロ波エネルギー照射によって容易に90
0℃を超える温度まで自己発熱する。即ち、混入されて
いる炭素源のマイクロ波による熱変換に加えるに、磁鉄
鉱の自己発熱も加わってマイクロ波エネルギーの熱変換
は急速に増大し、炭素源より発生するCOガスによる酸
化鉄の還元反応は幾何級数的に進むことになる。このこ
とから、マイクロ波照射による鉄酸化物の還元は、エネ
ルギー効率の点のみならず、極めて短い時間での反応に
よって金属鉄粉を製造可能である。
Therefore, magnetite (not only naturally-occurring magnetite but also mill scale obtained from a steelmaking process corresponds to this) can be easily heated to 90 times by microwave energy irradiation.
It self-heats to a temperature above 0 ° C. That is, in addition to the heat conversion of the mixed carbon source by microwaves, the heat conversion of microwave energy rapidly increases due to the self-heating of magnetite, and the reduction reaction of iron oxide by the CO gas generated from the carbon source. Will proceed geometrically. From this, the reduction of iron oxides by microwave irradiation can produce metallic iron powder not only in terms of energy efficiency but also by reaction in an extremely short time.

【0014】第三に、混合物に添加される炭酸塩につい
ては、周知の通り、例えば、炭酸カルシウムの熱分解に
よる炭酸ガスの各温度における分圧は、700℃におい
て22mmHg、900℃では793mmHg、100
0℃においては2942mmHgであるから、急速加熱
による混合物中におけるCO2 ガス分圧は爆発的に急上
昇する。一方、従来法による鉄酸化物と炭素源との還元
方法においては、当初のCO2 ガスは専ら空気中の酸素
と、加熱された炭素源から得られるものであるから、こ
のCO2 ガスが炭素源中の炭素と反応してCOガスとな
り、COガスが鉄酸化物と反応して初めてCO2 ガスに
酸化され、再び高温炭素源と反応してCOに転換される
というループを描くことになる。
Thirdly, regarding the carbonate added to the mixture, as is well known, for example, the partial pressure at each temperature of carbon dioxide gas due to the thermal decomposition of calcium carbonate is 22 mmHg at 700 ° C. and 793 mmHg at 900 ° C.
Since it is 2942 mmHg at 0 ° C., the CO 2 gas partial pressure in the mixture due to rapid heating explosively rises explosively. On the other hand, in the reduction process of the prior art iron oxide and carbon sources by, the initial CO 2 gas and oxygen exclusively in the air, since those obtained from the heated carbon source, the CO 2 gas is carbon It will react with carbon in the source to become CO gas, and CO gas will be oxidized to CO 2 gas only after reacting with iron oxide, and will react with the high temperature carbon source again to be converted into CO. .

【0015】又、本発明によれば、混合物中の炭素源が
マイクロ波エネルギーの変換によって急速に高温化する
とともに、混合物中の炭酸塩は同時に熱分解してCO2
ガスを放出し、このCO2 ガスが直接高温炭素源と接触
してCOガスに還元される。ところで、鉄酸化物の還元
はCOガスによって行なわれるのであり、反応速度の律
速は反応系内のCOガスの濃度によるものである。従っ
て、反応の加速にはCOガスの発生が不可欠であって、
本発明のように、COガスを炭酸塩の熱分解によるもの
とマイクロ波照射によって高温炭素源からによるものと
の両方で得るとすれば、その濃度は著しく高まる。即
ち、単に鉄酸化物と炭素源との混合体の加熱による還元
工程に、更に、上記混合体に炭酸塩を加えることによ
り、還元反応を爆発的に加速させるのである。
Further, according to the present invention, the carbon source in the mixture is rapidly heated to a high temperature by the conversion of microwave energy, and the carbonate in the mixture is simultaneously thermally decomposed to generate CO 2
The gas is released, and this CO 2 gas is directly contacted with the high temperature carbon source to be reduced to CO gas. By the way, the reduction of iron oxide is performed by CO gas, and the rate-determining reaction rate depends on the concentration of CO gas in the reaction system. Therefore, the generation of CO gas is indispensable for accelerating the reaction,
If CO gas is obtained both by thermal decomposition of carbonate and by high temperature carbon source by microwave irradiation, as in the present invention, the concentration is significantly increased. That is, the reduction reaction is explosively accelerated by further adding a carbonate to the mixture in the reduction step by simply heating the mixture of the iron oxide and the carbon source.

【0016】[0016]

【実施例】本発明は、鉄酸化物、炭素源及び炭酸塩の混
合物にマイクロ波を高密度で均一に照射させる必要があ
る。そのため、マイクロ波はその散乱を防ぎ、狭い領域
に照射可能で、しかも、混合物全体に均等に照射される
ように工夫したものでなければならない。一方、マイク
ロ波を照射された混合物は、900℃を超える高温に加
熱されるため、又、加熱される必要のない混合物の容器
は、最高温度となる1500℃の耐熱性を持つことと、
その材質はマイクロ波低誘電体で成形加工されるものが
望ましい。
EXAMPLES In the present invention, it is necessary to irradiate a mixture of an iron oxide, a carbon source and a carbonate with microwaves at a high density and uniformly. Therefore, microwaves must be devised so as to prevent their scattering, to be able to irradiate a narrow area, and to irradiate the entire mixture uniformly. On the other hand, since the mixture irradiated with microwaves is heated to a high temperature of over 900 ° C., the container of the mixture which does not need to be heated has a heat resistance of 1500 ° C. which is the maximum temperature.
It is desirable that the material be a microwave low dielectric material.

【0017】更に、この混合物を入れた容器は、マイク
ロ波加熱室に連続的に挿入され、且つ、押し出されて来
るため、マイクロ波加熱室の入口、出口等の開口部から
マイクロ波が漏洩する虞がある。このため、マイクロ波
加熱室の入口並びに出口に連結してマイクロ波吸収室を
設け、被加熱物をその中を通してマイクロ波を吸収させ
ることで、外部への漏洩を防止するようにしてある。
尚、従来の加熱法では、原料をペレットにした上で加熱
した方が還元反応はより速く進むが、マイクロ波加熱に
おいては、この原料をペレットにして行なうと部分的に
アークが発生し易く、そうなると全体の還元反応は進み
難くなる。このような理由から、本発明では、原料をペ
レットにはしないで、混合した状態のままでマイクロ波
加熱を行なう。
Further, the container containing this mixture is continuously inserted into the microwave heating chamber and pushed out, so that microwaves leak from the openings such as the inlet and the outlet of the microwave heating chamber. There is a risk. For this reason, a microwave absorption chamber is provided so as to be connected to the inlet and the outlet of the microwave heating chamber, and the microwave is absorbed through the object to be heated to prevent leakage to the outside.
In the conventional heating method, the reduction reaction proceeds faster if the raw material is pelletized and then heated, but in the microwave heating, when the raw material is pelletized, an arc is likely to occur partially, Then, the whole reduction reaction becomes difficult to proceed. For this reason, in the present invention, the microwave heating is performed in the mixed state without forming the raw material into pellets.

【0018】図1は本発明を実施するための装置の一例
であるが、マイクロ波を利用する鉄粉の製造装置は、マ
イクロ波発信装置Aで発信されたマイクロ波を誘導でき
るトンネルキルン型のマイクロ波加熱兼保温用電気炉装
置(以下、保温用電気炉装置という)Bと、鉄酸化物、
炭素源及び炭酸塩の混合物(原料)を搭載して保温用電
気炉装置B内を通過できる移動装置Cとからなる。マイ
クロ波発信装置Aは、マイクロ波発信機10、ダミーロ
ード11を付設するサーキュレータ12、パワーモニタ
ー14、インピーダンス調整器16等から構成され、マ
イクロ波発信機10で発信されたマイクロ波をインピー
ダンス調整器16で調整して導波管18を通して保温用
電気炉装置Bまで送るものである。
FIG. 1 shows an example of an apparatus for carrying out the present invention. An iron powder manufacturing apparatus utilizing microwaves is of a tunnel kiln type capable of guiding the microwaves transmitted by the microwave transmitting apparatus A. Microwave heating and heat retention electric furnace device (hereinafter referred to as heat insulation electric furnace device) B, iron oxide,
It comprises a moving device C which carries a mixture (raw material) of a carbon source and a carbonate and which can pass through the inside of the electric insulation furnace device B for heat insulation. The microwave transmission device A includes a microwave oscillator 10, a circulator 12 having a dummy load 11 attached thereto, a power monitor 14, an impedance adjuster 16, and the like. The microwave transmitted by the microwave oscillator 10 is an impedance adjuster. It is adjusted by 16 and sent to the heat insulation electric furnace device B through the waveguide 18.

【0019】保温用電気炉装置Bは、マイクロ波低誘電
体であるセラミックファイバー等で炉壁を構成されるマ
イクロ波加熱兼保温用電気炉(以下、保温用電気炉とい
う)20で構成され、内部に炭化珪素発熱線22やスタ
ーラファン24等を装備して移動装置Cで送られて来る
原料を加熱するとともに、これにマイクロ波発信装置A
から送られて来たマイクロ波を照射するものである。
尚、保温用電気炉装置Bには、保温用電気炉20に隣接
して、移動装置Cの移動方向上流側にマイクロ波吸収室
26を、下流側に冷却室兼マイクロ波吸収室(以下、冷
却室という)28をそれぞれ設けてある。このうち冷却
室28は、保温用電気炉20の下流側出口部分から漏洩
するマイクロ波を吸収するとともに、製造された金属鉄
粉を冷却するものであり、N2 ガスの吹出口32が設け
られているものである。
The heat-retaining electric furnace apparatus B comprises a microwave heating and heat-retaining electric furnace (hereinafter referred to as a heat-retaining electric furnace) 20 having a furnace wall made of a ceramic material such as a microwave low dielectric material. A silicon carbide heating wire 22 and a stirrer fan 24 are installed inside to heat the raw material sent by the moving device C, and the microwave transmitting device A
It irradiates the microwaves sent from.
In addition, in the heat-retaining electric furnace B, adjacent to the heat-retaining electric furnace 20, a microwave absorption chamber 26 is provided on the upstream side in the moving direction of the moving device C, and a cooling chamber / microwave absorption chamber is provided on the downstream side (hereinafter, Each of the cooling chambers) 28 is provided. Of these, the cooling chamber 28 absorbs microwaves leaking from the downstream side outlet portion of the heat-retaining electric furnace 20 and cools the produced metal iron powder, and is provided with a N 2 gas outlet 32. It is what

【0020】移動装置Cは、保温用電気炉B内を貫通し
て敷設されるマイクロ波低誘電体であるセラミック製等
のガイドウェイ(本例ではローラコンベアを示した)3
4の上にプッシャー35で押されて移動する同じくマイ
クロ波低誘電体であるセラミック製等のトレー36が載
せられているものであり、原料を定量フィーダー38か
ら受けて保温用電気炉装置B内を通過し、この間に原料
にマイクロ波の照射を受けるものである。図2はトレー
36の横断面図であるが、このトレー36は底部に二重
の重なり部を有する分割された左右対称型の構造をして
おり、この重なり部でマイクロ波照射による急速加熱に
基づく熱膨張を吸収し、破損が防止されるように工夫さ
れたものである。
The moving device C is a guideway made of ceramic, which is a microwave low-dielectric material (a roller conveyor is shown in this example), which is laid so as to penetrate through the heat insulating electric furnace B.
4, a tray 36 made of ceramic or the like, which is also a microwave low-dielectric material and is moved by being pushed by the pusher 35, is placed on the inside of the electric furnace device B for heat reception by receiving the raw material from the quantitative feeder 38. The material is irradiated with microwaves during this period. FIG. 2 is a cross-sectional view of the tray 36. This tray 36 has a divided left-right symmetrical structure having a double overlapping portion at the bottom, and this overlapping portion is used for rapid heating by microwave irradiation. It was devised to absorb the thermal expansion due to it and prevent damage.

【0021】以上の構成により、先ず、原料を搭載した
トレー36はプッシャー35で押されてマイクロ波吸収
室26に入り、次いで保温用電気炉20内に送り込ま
れ、ここでマイクロ波照射によって900℃以上に加熱
され、鉄酸化物は還元されて金属鉄粉になる。保温用電
気炉20を加熱してマイクロ波加熱と保温とを同時に行
うのは、本発明の大切な部分であり、これは、マイクロ
波による鉄酸化物の還元を速く、効率良く行なうために
は、この保温を如何にうまく行なうかが重要なことであ
るからである。
With the above structure, first, the tray 36 on which the raw material is loaded is pushed by the pusher 35 to enter the microwave absorption chamber 26, and then is sent into the heat insulation electric furnace 20 where the microwave irradiation is performed at 900 ° C. By heating above, the iron oxide is reduced to metallic iron powder. It is an important part of the present invention to heat the heat-retaining electric furnace 20 to perform microwave heating and heat-retaining at the same time. This is to reduce the iron oxides by microwaves quickly and efficiently. This is because it is important how well this heat retention is performed.

【0022】マイクロ波加熱が終わって鉄酸化物が還元
されて金属鉄粉になったものは、一旦、冷却室28で冷
却されて保温用電気炉装置Bから排出される。これは、
製造された金属鉄粉の再酸化を防止するためであり、冷
却と同時にN2 ガスを吹きつけることで行う。冷却室2
8を出た金属鉄粉は磁選機40で磁選され、純粋な鉄粉
(製品)のみホッパー42へ採集される。尚、このとき
前記した分割型のトレー36を用いれば、左右に開くだ
けで製品は容易に放出される。
After the microwave heating is completed and the iron oxide is reduced to metallic iron powder, it is once cooled in the cooling chamber 28 and discharged from the heat insulating electric furnace apparatus B. this is,
This is to prevent re-oxidation of the produced metallic iron powder, and is performed by blowing N 2 gas at the same time as cooling. Cooling room 2
The metallic iron powder exiting from No. 8 is magnetically separated by the magnetic separator 40, and only pure iron powder (product) is collected in the hopper 42. At this time, if the above-mentioned split type tray 36 is used, the product can be easily discharged simply by opening it to the left and right.

【0023】図3は以上の装置の他の例であるが、この
例における保温用電気炉装置Bは、金属製の炉壁を有し
てレモン形に形成される殻状の保温用電気炉50で構成
してある(52は導波管10の接続部)。又、移動装置
Cは、この保温用電気炉50内を貫通し、内周に螺旋突
条54を形成したセラミック製等の移送管56の両端を
回転支持部58で支持し、一端に駆動部60を取り付け
た構成にしてある。尚、移送管56と保温用電気炉50
の炉壁との間の空間にはセラミックファイバー62等を
詰めておく。
FIG. 3 shows another example of the above-mentioned apparatus. A heat-retaining electric furnace apparatus B in this example is a shell-like heat-retaining electric furnace having a metal furnace wall and formed in a lemon shape. It is constituted by 50 (52 is a connecting portion of the waveguide 10). Further, the moving device C penetrates through the heat-retaining electric furnace 50 and supports both ends of a transfer pipe 56 made of ceramic or the like having a spiral projection 54 formed on the inner periphery thereof by a rotation support part 58, and a drive part at one end. The configuration is such that 60 is attached. In addition, the transfer pipe 56 and the heat-retaining electric furnace 50
A ceramic fiber 62 or the like is packed in the space between the furnace wall and the furnace wall.

【0024】以上により、原料を定量フィーダー38か
ら移送管56に供給し、駆動部60を駆動して移送管5
6を回転させると、原料は螺旋突条54の作用で保温用
電気炉50内を移送され、この間にマイクロ波の照射を
受けて還元され、金属鉄粉になる。尚、保温用電気炉5
0の両端を絞ったのは、マイクロ波の漏洩を防ぐためで
あり、セラミックファイバー62を詰めたのは原料の保
温性を向上させるためである。
As described above, the raw material is supplied from the quantitative feeder 38 to the transfer pipe 56, and the driving unit 60 is driven to transfer the transfer pipe 5.
When 6 is rotated, the raw material is transported in the heat insulating electric furnace 50 by the action of the spiral ridge 54, is irradiated with microwaves during this period, and is reduced to become metallic iron powder. In addition, the electric furnace 5 for heat retention
The reason that both ends of 0 are narrowed is to prevent microwave leakage, and the reason that the ceramic fiber 62 is packed is to improve the heat retention of the raw material.

【0025】[0025]

【実験例】[Experimental example]

(実験例1)38wt%のミルスケール(−500μm
に選別)及び25wt%のインド産のバイラディラ赤鉄
鉱粉(−250μmに選別)と31wt%のチャー炭
(−1000μmに選別)と6wt%の炭酸カルシウム
(−297μmに選別)をよく混合してるつぼへ入れ、
セラミックファイバーで保温して、マイクロ波オーブン
内(周波数2450MHz )で、7分間加熱後、磁選
し、磁着物と非磁着物の重量を測定した後、磁着物の金
属鉄及びトータル鉄の品位%、非磁着物のトータル鉄の
品位%を化学分析して求め、次式で還元率を求めた。
(Experimental Example 1) 38 wt% mill scale (-500 μm
Well) and 25 wt% of Indian biradira hematite powder (sorted to -250 μm), 31 wt% char charcoal (sorted to -1000 μm) and 6 wt% calcium carbonate (sorted to -297 μm). Put in,
The mixture was kept at ceramic fibers, in a microwave oven (frequency 2450MH z), after heating for 7 minutes, and magnetic separation, magnetically attracted material and a non-magnetically attracted after measuring the weight of the material, grade% of metallic iron and total iron magnetically attracted material % Of the total iron of the non-magnetic substance was obtained by chemical analysis, and the reduction rate was obtained by the following formula.

【0026】還元率=(磁着物の重量)×(磁着物の金
属鉄の品位%)/〔(磁着物の重量)×(磁着物のトー
タル鉄の品位%)〕+〔(非磁着物の重量)×(非磁着
物のトータル鉄の品位%)〕×100 この計算によると、還元率は94.9%であった。
Reduction ratio = (weight of magnetic substance) × (grade of iron iron of magnetic substance) / [(weight of magnetic substance) × (grade of total iron of magnetic substance)] + [(non-magnetic substance) Weight) × (% of total iron content of non-magnetic substance)] × 100 According to this calculation, the reduction rate was 94.9%.

【0027】(実験例2)実験例1で使用した炭酸カル
シウムを加えず、その他の条件は全く同じにして同様の
実験を行なった。結果は、還元率43.8%となり、還
元はあまり進んでいなかった。この実験より、炭酸カル
シウム等の炭酸塩は還元反応促進剤的な役割を果たして
いることが判明し、マイクロ波を利用する鉄粉の製造に
は必要不可欠な添加剤であると言える。
(Experimental Example 2) The same experiment was conducted under the same conditions except that the calcium carbonate used in Experimental Example 1 was not added. As a result, the reduction rate was 43.8%, and the reduction did not proceed so much. From this experiment, it was found that carbonates such as calcium carbonate play a role as a reduction reaction accelerator, and it can be said that they are essential additives for the production of iron powder using microwaves.

【0028】(実験例3)同様に、炭酸カルシウムの含
量を0〜18wt%の範囲で変えて還元率を調べてみ
た。図4はその結果を示すものであるが、これから、実
験例1で行ったように6wt%位の添加量が最適で、こ
れより多くても還元率は徐々に低下することがわかっ
た。これは、CaCO3 の分解反応が吸熱反応であるた
め、混合物全体の温度上昇が遅くなるためであると思わ
れる。
(Experimental Example 3) Similarly, the reduction rate was examined by changing the content of calcium carbonate in the range of 0 to 18 wt%. FIG. 4 shows the results. From this, it was found that the addition amount of about 6 wt% was optimal as in Experimental Example 1, and the reduction rate gradually decreased even if it was more than this. This is probably because the decomposition reaction of CaCO 3 is an endothermic reaction, which slows the temperature rise of the entire mixture.

【0029】(実験例4)実験例1及び2で使用したチ
ャー炭10gを図5に示すような3通りの保温方法でマ
イクロ波加熱を行ない、それぞれの温度上昇を調べた。
このときの温度測定は、試料に挿入した保護管を通して
放射温度計で連続的に行なった。その結果を図6に示
す。(a)は、試料を入れたるつぼの側面のみをアルミ
ナの筒で囲ったもので、これを加熱すると、850℃ま
で上昇し、それ以後は同じ温度を保った。(b)は、少
し大きめのるつぼを上からかぶせたもので、この場合
は、950℃まで上昇して一定を保った。(c)は、試
料を入れたるつぼと上からかぶせたるつぼの間にセラミ
ックファイバーを詰めたもので、この方法では1080
℃まで上昇して一定になった。しかし、いずれの場合で
あっても、電源を切ると温度は瞬間的に降下した。
(Experimental Example 4) 10 g of char charcoal used in Experimental Examples 1 and 2 were subjected to microwave heating by three kinds of heat retaining methods as shown in FIG. 5, and the temperature rise of each was examined.
The temperature at this time was continuously measured with a radiation thermometer through a protective tube inserted in the sample. The result is shown in FIG. In (a), only the side surface of the crucible containing the sample is surrounded by a cylinder of alumina. When this is heated, the temperature rises to 850 ° C., and the same temperature is maintained thereafter. In (b), a slightly larger crucible was covered from above, and in this case, the temperature was raised to 950 ° C. and kept constant. (C) is one in which ceramic fibers are packed between the crucible containing the sample and the crucible covered from above, and in this method 1080
It rose to ℃ and became constant. However, in either case, the temperature dropped momentarily when the power was turned off.

【0030】この結果からわかるように、高温において
は、被加熱物中から発散する熱量が非常に大きいので、
保温方法によって被加熱物の温度の上がり方が大きく違
ってくる。ところが、還元反応の律速過程であるCOを
形成するブードア反応は高温であるほど有利に進むの
で、如何に保温をうまくして被加熱物の熱を逃がさない
ようにしてマイクロ波加熱をしてやるかということが還
元反応を速く、しかも、効率よく進めるために重要なこ
とである。このような発見が鉄酸化物の炭素還元をマイ
クロ波加熱によって保温用電気炉装置内で行なうという
着想につながったのである。
As can be seen from these results, at a high temperature, the amount of heat radiated from the object to be heated is very large.
How the temperature of the object to be heated rises greatly depends on the method of heat retention. However, since the Boudore reaction that forms CO, which is the rate-determining process of the reduction reaction, advances more favorably at higher temperatures, how to keep the heat well so that the heat of the object to be heated is not released and microwave heating is performed. That is important for the reduction reaction to proceed rapidly and efficiently. These discoveries led to the idea that carbon reduction of iron oxides was carried out by microwave heating in an electric furnace for heat insulation.

【0031】[0031]

【発明の効果】以上、本発明は、前記した通りのもので
あるから、鉄酸化物を鉄粉にまで還元する過程で供給し
なければならない熱エネルギーを節約化でき、且つ、そ
の反応時間を大幅に短縮できたのである。従って、鉄粉
製造の効率を高め、コストを低減できる。
As described above, according to the present invention, as described above, it is possible to save the heat energy that must be supplied in the process of reducing iron oxide to iron powder, and to reduce the reaction time. It was able to be greatly shortened. Therefore, the efficiency of iron powder production can be improved and the cost can be reduced.

【図面の簡単な説明】[Brief description of drawings]

【図1】本発明の実施例を示す鉄粉製造装置の説明図で
ある。
FIG. 1 is an explanatory view of an iron powder manufacturing apparatus showing an embodiment of the present invention.

【図2】上記装置に用いるトレーの横断面図である。FIG. 2 is a cross-sectional view of a tray used in the above device.

【図3】本発明の他の実施例を示す鉄粉製造装置の説明
図である。
FIG. 3 is an explanatory view of an iron powder manufacturing apparatus showing another embodiment of the present invention.

【図4】炭酸塩の添加量と鉄酸化物の還元率との関係を
示すグラフである。
FIG. 4 is a graph showing the relationship between the amount of carbonate added and the reduction rate of iron oxide.

【図5】チャー炭の保温方法を示す説明図である。FIG. 5 is an explanatory diagram showing a method of keeping heat of char charcoal.

【図6】チャー炭の保温方法と温度上昇との関係を示す
グラフである。
FIG. 6 is a graph showing a relationship between a method for keeping char charcoal and a temperature rise.

【符号の説明】[Explanation of symbols]

A マイクロ波発信装置 B マイクロ波加熱兼保温用電気炉装置 C 移動装置 20 マイクロ波加熱室兼保温用電気炉 34 ガイドウェイ 36 トレー 50 マイクロ波加熱室兼保温用電気炉 54 螺旋突条 56 移送管 A microwave transmission device B microwave heating / heat-retaining electric furnace device C transfer device 20 microwave heating chamber / heat-retaining electric furnace 34 guideway 36 tray 50 microwave heating chamber / heat-retaining electric furnace 54 spiral ridge 56 transfer pipe

Claims (6)

【特許請求の範囲】[Claims] 【請求項1】 鉄鉱石、ミルスケール等の粉砕した鉄酸
化物と、コークス、チャー炭、活性炭、微粉炭等の炭素
を主成分とするマイクロ波高誘導体である炭素源と、炭
酸カルシウム、炭酸マグネシウム、炭酸ナトリウム等の
炭酸塩とを混合し、これら混合物にマイクロ波を照射し
て炭素源を900℃を越えるまで内部発熱させるととも
に、混合物中の炭酸塩の熱分解によって発生したCO2
ガスと反応させてCOガスに変換し、このCOガスによ
って鉄酸化物を還元させて鉄粉を製造することを特徴と
するマイクロ波を利用する鉄粉の製造方法。
1. A crushed iron oxide such as iron ore and mill scale, and a carbon source which is a microwave high-derivative containing carbon as a main component, such as coke, char charcoal, activated carbon, and pulverized coal, and calcium carbonate and magnesium carbonate. , A carbonate such as sodium carbonate are mixed, and the mixture is irradiated with microwaves to internally heat the carbon source until the temperature exceeds 900 ° C., and CO 2 generated by thermal decomposition of the carbonate in the mixture is generated.
A method for producing iron powder using microwaves, which comprises reacting with a gas to convert it into CO gas, and reducing the iron oxide by this CO gas to produce iron powder.
【請求項2】 請求項1の製造方法を実施する装置であ
って、この装置が、マイクロ波を発信するマイクロ波発
信装置と、マイクロ波発信装置から発信されたマイクロ
波を導いて照射できるマイクロ波加熱室兼保温用電気炉
装置と、鉄酸化物、炭素源及び炭酸塩の混合物を搭載し
てマイクロ波加熱室兼保温用電気炉装置内を移動し、混
合物にマイクロ波の照射を受けることができる移動装置
とから構成されることを特徴とするマイクロ波を利用す
る鉄粉の製造装置。
2. A device for carrying out the manufacturing method according to claim 1, wherein the device is a microwave transmitting device for transmitting microwaves, and a microwave capable of guiding and irradiating the microwaves transmitted from the microwave transmitting device. A microwave heating chamber / heat-retaining electric furnace device and a mixture of iron oxide, a carbon source and a carbonate are mounted to move inside the microwave heating chamber / heat-retaining electric furnace device, and the mixture is irradiated with microwaves. An iron powder manufacturing apparatus utilizing microwaves, which is characterized by comprising a moving device capable of
【請求項3】 請求項2のマイクロ波加熱室兼保温用電
気炉装置を構成するマイクロ波加熱室兼保温用電気炉
に、移動装置の移動方向上流側にマイクロ波吸収室、下
流側に冷却室兼マイクロ波吸収室をそれぞれ付設したこ
とを特徴とするマイクロ波を利用する鉄粉の製造装置。
3. The microwave heating chamber / heat insulating electric furnace constituting the microwave heating chamber / heat insulating electric furnace device according to claim 2, wherein a microwave absorption chamber is provided on the upstream side in the moving direction of the moving device and a cooling is provided on the downstream side. An apparatus for producing iron powder using microwaves, which is provided with a chamber and a microwave absorption chamber, respectively.
【請求項4】 請求項2又は3のマイクロ波加熱室兼保
温用電気炉がトンネルキルン型の炉であり、移動装置が
ガイドウェイ上をトレーが移動するものであることを特
徴とするマイクロ波を利用する鉄粉の製造装置。
4. The microwave heating chamber / heat-retaining electric furnace according to claim 2 or 3 is a tunnel kiln type furnace, and the moving device is one in which a tray moves on a guideway. Iron powder manufacturing equipment that uses
【請求項5】 請求項4のトレーが底部に重なり部を有
する左右分割型のものであることを特徴とするマイクロ
波を利用する鉄粉の製造装置。
5. An apparatus for producing iron powder using microwaves, wherein the tray according to claim 4 is a left-right split type having an overlapping portion on the bottom.
【請求項6】 請求項2又は3のマイクロ波加熱室兼保
温用電気炉が殻状の炉であり、移動装置が内周に螺旋突
条を形成した回転する移送管であることを特徴とするマ
イクロ波を利用する鉄粉の製造装置。
6. The microwave heating chamber / heat-retaining electric furnace according to claim 2 or 3 is a shell-shaped furnace, and the moving device is a rotating transfer tube having a spiral ridge formed on the inner circumference. Iron powder manufacturing equipment using microwave.
JP31769392A 1992-08-17 1992-09-14 Method and apparatus for producing iron powder using microwaves Expired - Lifetime JP3280435B2 (en)

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JP4-241349 1992-08-17
JP24134992 1992-08-17
JP31769392A JP3280435B2 (en) 1992-08-17 1992-09-14 Method and apparatus for producing iron powder using microwaves

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