JP5000437B2 - Pre-treatment method for high crystal water ore - Google Patents
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Description
本発明は、製鉄プロセスや触媒及び担体の製造プロセスで使用される鉄鉱石の中で、特に結晶水を３ｍａｓｓ％以上含有する高結晶水鉄鉱石の事前処理方法に関する。 The present invention relates to a pretreatment method for a high-crystal water ore containing 3 mass% or more of crystal water among iron ores used in an iron making process or a catalyst and carrier manufacturing process.
製鉄原料に用いられる鉄鉱石には、直接高炉に装入される粒径約１０〜３０ｍｍの塊鉱石と、粒径１０ｍｍ以下の粉鉱石があり、粉鉱石は、石灰石などの副原料やコークス粉などの炭材と混合し、水を添加して造粒して、空気を吸引しながら炭材を燃焼させて焼結し、焼結鉱として高炉に装入される。 Iron ore used for ironmaking raw materials includes massive ores with a particle size of about 10 to 30 mm and powdered ores with a particle size of 10 mm or less that are charged directly into the blast furnace, and the powdered ores are auxiliary materials such as limestone and coke powder. It is mixed with charcoal such as water, granulated by adding water, burned with charcoal while sucking air, sintered, and charged into a blast furnace as sintered ore.
鉄分を３０ｍａｓｓ％以上含有する鉄鉱石には、Ｆｅ3Ｏ4を主成分とする磁鉄鉱、Ｆｅ2Ｏ3を主成分とする赤鉄鉱、Ｆｅ2Ｏ3・ｎＨ2Ｏを主成分とする褐鉄鉱がある（例えば非特許文献１、参照）。褐鉄鉱の主成分であるＦｅ2Ｏ3・ｎＨ2Ｏは、大部分は不純な針鉄鉱｛ゲーザイト；α-ＦｅＯ(ＯＨ)｝、または鱗鉄鉱｛レピドクロサイト；γ-ＦｅＯ(ＯＨ)｝と言われており（例えば非特許文献２、参照）、現在、製鉄原料に用いられる褐鉄鉱は、ゲーサイトが主体である。日本工業規格（ＪＩＳ）に規定される鉄鉱石−化合水定量方法（Ｍ ８２１１）の化合水（非特許文献３、参照）は、鉄鉱石分析試料を１０５℃から９５０℃に加熱される間に発生する水分を指し、その大部分は褐鉄鉱、すなわちゲーサイトから発生していると考えられている（例えば非特許文献４、参照）。 The iron ore containing iron or 30 mass%, magnetite mainly containing Fe 3 O 4, hematite composed mainly of Fe 2 O 3, is limonite mainly containing Fe 2 O 3 · nH 2 O Yes (see Non-Patent Document 1, for example). Fe 2 O 3 .nH 2 O, the main component of limonite, is mostly impure goethite {gezite; α-FeO (OH)}, or sprite {repidocrosite; γ-FeO (OH)}. It is said (see Non-Patent Document 2, for example), and limonite used for iron-making raw materials is mainly goethite. The combined water (see Non-Patent Document 3) of the iron ore-combined water quantification method (M 8211) defined in Japanese Industrial Standard (JIS) is used while the iron ore analysis sample is heated from 105 ° C to 950 ° C. It refers to the generated water, and most of it is considered to be generated from limonite, that is, goethite (see Non-Patent Document 4, for example).
しかしながら、ゲーサイトを単に脱水温度まで加熱すると、鉄鉱石粒子に亀裂が生じて粉化が起こる。 However, when the goethite is simply heated to the dehydration temperature, the iron ore particles crack and cause pulverization.
高炉に装入される塊鉱石は高炉内で加熱されながら還元ガスにより還元され、また、焼結工程で使用される粉鉱石は、焼結機内で空気を吸引しながら炭材を燃焼させて加熱、焼結される。この際、結晶水含有率の高い鉄鉱石をそのまま高炉または焼結機に装入すると、高炉または焼結機内の通気性が阻害され、高炉内での還元効率、あるいは焼結機での生産性及び成品歩留が低下するという問題が生じる。 The lump ore charged in the blast furnace is reduced by reducing gas while being heated in the blast furnace, and the fine ore used in the sintering process is heated by burning carbonaceous materials while sucking air in the sintering machine. Sintered. At this time, if iron ore with a high crystal water content is charged into a blast furnace or a sintering machine as it is, the air permeability in the blast furnace or the sintering machine is hindered, the reduction efficiency in the blast furnace, or the productivity in the sintering machine. In addition, there is a problem that the product yield is lowered.
従って、このような結晶水含有率の高い鉄鉱石（以下、高結晶水鉄鉱石という場合もある）は、高炉に装入する前、あるいは焼結機に装入する原料の製粒前に、加熱処理などにより鉄鉱石中に結晶水を脱水することが望ましい。しかしながら、高結晶水鉄鉱石を単に加熱処理するだけでは、鉄鉱石中に亀裂が発生し、粉化が生じるため、処理後に鉄鉱石の圧潰強度の低下や、粒度の低下が生じるという問題があった。 Therefore, such an iron ore with a high crystal water content (hereinafter sometimes referred to as a high crystal water ore) is charged before being charged into the blast furnace or before granulating the raw material charged into the sintering machine. It is desirable to dehydrate the crystal water in the iron ore by heat treatment or the like. However, simply heat-treating high-crystal hydrous iron ore causes cracks in the iron ore and pulverization, resulting in a decrease in iron ore crushing strength and particle size after processing. It was.
本発明は、上記従来技術の現状を鑑みて、結晶水含有率の高い鉄鉱石を加熱処理する際に、鉄鉱石粒子中の結晶水の脱水に伴う亀裂発生や粉化を抑制しつつ、気孔率が高く、かつ圧潰強度が高い鉄鉱石に改質するための高結晶水鉄鉱石の事前処理方法を提供することを目的とする。 In view of the current state of the prior art described above, the present invention suppresses cracking and pulverization associated with dehydration of crystal water in iron ore particles when heat-treating iron ore having a high content of crystal water. An object of the present invention is to provide a method for pretreating high crystal hydrous iron ore for reforming to iron ore having a high rate and high crushing strength.
本発明は上記課題を解決するためになされたものであり、その本発明の要旨とするところは、以下の通りである。
（１）結晶水を３ｍａｓｓ％以上含有する鉄鉱石を、２５０℃以上の温度で、かつ飽和水蒸気圧以上の圧力の流体において加熱することを特徴とする高結晶水鉄鉱石の事前処理方法。
（２）前記流体は、空気、窒素、または、水の何れかであることを特徴とする上記（１）記載の高結晶水鉄鉱石の事前処理方法。
The present invention has been made to solve the above problems, and the gist of the present invention is as follows.
(1) A pre-processing method for high crystal water iron ore, characterized in that iron ore containing 3 mass% or more of crystal water is heated in a fluid at a temperature of 250 ° C. or higher and a pressure equal to or higher than a saturated water vapor pressure.
(2) The high-crystal water ore pretreatment method according to the above (1), wherein the fluid is air, nitrogen, or water.
本発明によれば、高結晶水鉄鉱石を脱水し、高炉や焼結工程で利用する場合に、通気性を確保し、効率的に高炉内での還元、あるいは焼結工程での効率的な焼結を行える、気孔率が高く、かつ圧潰強度の高い酸化鉄粒子製造をすることができる。 According to the present invention, when high-crystal hydrous iron ore is dehydrated and used in a blast furnace or a sintering process, air permeability is ensured, and the reduction in the blast furnace or efficient in the sintering process is efficiently performed. Iron oxide particles with high porosity and high crushing strength that can be sintered can be produced.
以下に本発明の詳細を説明する。 Details of the present invention will be described below.
本発明が対象とする結晶水を３ｍａｓｓ％以上含む鉄鉱石は、ＪＩＳ Ｍ８２１１「鉄鉱石−化合水定量方法」に定められた方法によって測定される化合水、つまり、鉄鉱石試料を１０５℃から９５０℃に加熱する間に発生する水分が３ｍａｓｓ％以上を含む鉄鉱石を意味する。なお、ここで、測定対象とする鉄鉱石は、ＪＩＳ Ｍ８２１２「鉄鉱石−全鉄定量方法」に定められた方法によって定量される鉄含有率が３０ｍａｓｓ％以上の鉱石を意味し、化合水の大部分は、一般に以下のゲーサイト鉱物から発生したものと考えられている。 The iron ore containing 3 mass% or more of crystal water targeted by the present invention is a compound water measured by the method defined in JIS M8211 “Iron Ore-Compound Water Determination Method”, that is, an iron ore sample of 105 ° C. to 950 ° C. It means iron ore containing 3 mass% or more of water generated during heating to ° C. Here, the iron ore to be measured means an ore having an iron content of 30 mass% or more quantified by a method defined in JIS M8212 “Iron ore-total iron quantification method”. The part is generally considered to originate from the following goethite minerals.
ゲーサイト鉱物は、ＦｅＯ（ＯＨ）の構造を持ち、２５０℃以上の温度で加熱することにより、下記（１）式に従って分解・脱水が起こり、ヘマタイト（Ｆｅ2Ｏ3）に変化する。この際、理論的には１０．１４ｍａｓｓ％の質量減少が生じる。 The goethite mineral has a structure of FeO (OH), and when heated at a temperature of 250 ° C. or higher, decomposition and dehydration occur according to the following formula (1), and changes to hematite (Fe 2 O 3 ). In this case, theoretically, a mass reduction of 10.14 mass% occurs.
２ＦｅＯ（ＯＨ）→Ｆｅ2Ｏ3＋Ｈ2Ｏ ・・・（１）
実際のゲーサイト鉱石には、ゲーサイト以外にもヘマタイト（α−Ｆｅ2Ｏ3）や石英（ＳｉＯ2）、カオリン（Ａｌ2Ｓｉ2Ｏ5（ＯＨ）4）などの粘土鉱物などが含まれているため、化合水が１０ｍａｓｓ％を超えることはごく稀である。
2FeO (OH) → Fe 2 O 3 + H 2 O (1)
Actual goethite ores include clay minerals such as hematite (α-Fe 2 O 3 ), quartz (SiO 2 ) and kaolin (Al 2 Si 2 O 5 (OH) 4 ) in addition to goethite. Therefore, it is rare that the combined water exceeds 10 mass%.
通常、ゲーサイトを脱水する場合は、常圧・大気下で加熱するが、脱水する際に水は蒸気となって脱離するため、１０００倍以上の体積膨張が起こり、鉄鉱石粒子内に亀裂が発生して、粒子の圧潰強度の低下や、それに伴う粉化が起こる。 Normally, when dehydrating goethite, it is heated at normal pressure and in the atmosphere, but when dehydrating, water desorbs as vapor, causing volume expansion of 1000 times or more and cracking in iron ore particles. Occurs, resulting in a decrease in the crushing strength of the particles and accompanying powdering.
本発明は、ゲーサイトが脱水する際に、脱離する水の体積膨張を小さくすることによって、鉄鉱石粒子内の亀裂の発生を抑制して、鉄鉱石粒子の圧潰強度の低下や、それに伴う粉化を抑えるものである。 The present invention suppresses the occurrence of cracks in iron ore particles by reducing the volume expansion of desorbed water when the goethite is dehydrated, thereby reducing the crushing strength of iron ore particles and accompanying it It suppresses pulverization.
図１に、本発明の実施形態の一例として、高結晶水鉄鉱石の事前処理プロセスを示す。１は流体容器、２は昇圧装置、３は圧力容器、４は加熱炉、５は背圧調整器、６は圧力計、７は温度計である。流体としては、空気、窒素、アルゴンなどの気体や、超臨界流体、水または水溶液の液体の何れかが使用できる。安価に入手できる点から空気や水を流体として使用するのが実用面から好ましい。 FIG. 1 shows a pretreatment process of a high-crystal water ore as an example of an embodiment of the present invention. 1 is a fluid container, 2 is a pressure increasing device, 3 is a pressure container, 4 is a heating furnace, 5 is a back pressure regulator, 6 is a pressure gauge, and 7 is a thermometer. As the fluid, any of a gas such as air, nitrogen, and argon, a supercritical fluid, water, or an aqueous solution can be used. From a practical point of view, it is preferable to use air or water as a fluid because it can be obtained at low cost.
結晶水を３ｍａｓｓ％以上含む高結晶水鉄鉱石を圧力容器３に装入し、次に流体容器１から流体をポンプなどの昇圧装置２によって圧力容器３内に導入して、昇圧装置２と背圧調整器５の間の圧力が２５０℃以上の所定温度における飽和水蒸気圧以上の所定圧力に調整する。加熱炉４の温度を２５０℃以上の所定温度まで上昇し、圧力容器３内の高結晶水鉄鉱石を２５０℃以上の温度で、飽和水蒸気圧以上の流体中で加熱脱水処理する。 A high crystalline hydrous ore containing 3 mass% or more of crystal water is charged into the pressure vessel 3, and then fluid is introduced from the fluid vessel 1 into the pressure vessel 3 by a booster 2 such as a pump. The pressure between the pressure regulators 5 is adjusted to a predetermined pressure equal to or higher than the saturated water vapor pressure at a predetermined temperature equal to or higher than 250 ° C. The temperature of the heating furnace 4 is raised to a predetermined temperature of 250 ° C. or higher, and the high crystalline hydrous ore in the pressure vessel 3 is heated and dehydrated at a temperature of 250 ° C. or higher in a fluid having a saturated water vapor pressure or higher.
高結晶水鉄鉱石を所定時間加熱処理した後、加熱炉４の温度を常温まで低下させ、さらに、背圧調整器の圧力を常圧まで低下した後、圧力容器３内から加熱脱水処理した鉄鉱石を取り出す。 After heat-treating the high crystalline hydrous ore for a predetermined time, the temperature of the heating furnace 4 is lowered to room temperature, the pressure of the back pressure regulator is lowered to normal pressure, and then the iron ore subjected to heat dehydration treatment from the pressure vessel 3 Remove the stone.
本発明において、高結晶水鉄鉱石の主要鉱物であるゲーサイト鉱物を上記（１）式により脱水し、ヘマタイト（Ｆｅ2Ｏ3）に改質するためには、２５０℃以上の温度で加熱する必要がある。 In the present invention, the goethite mineral, which is the main mineral of the high crystalline hydrous ore, is dehydrated according to the above formula (1) and is heated to a temperature of 250 ° C. or higher in order to be modified into hematite (Fe 2 O 3 ). There is a need.
図５に、結晶水量が７．５ｍａｓｓ％の高結晶水鉄鉱石を飽和水蒸気圧以上の圧力の水中で処理する際の温度と、処理後の鉄鉱石中の結晶水量の関係を示す。なお、飽和水蒸気圧は、25℃で大気圧、100℃で0.5 MPa、150℃で1MPa、200℃で3MPa、250℃で5MPa、300℃で10MPa、350℃で20MPaに設定した。 FIG. 5 shows the relationship between the temperature at which high crystal hydrous ore having a crystal water amount of 7.5 mass% is treated in water having a pressure equal to or higher than the saturated water vapor pressure and the amount of crystal water in the iron ore after the treatment. The saturated water vapor pressure was set to atmospheric pressure at 25 ° C, 0.5 MPa at 100 ° C, 1 MPa at 150 ° C, 3 MPa at 200 ° C, 5 MPa at 250 ° C, 10 MPa at 300 ° C, and 20 MPa at 350 ° C.
図５から、結晶水量が７．５ｍａｓｓ％の高結晶水鉄鉱石を処理する際の温度を２００℃以上とすることで高結晶水鉄鉱石中のゲーサイトに起因する結晶水を脱水により結晶水量３ｍａｓｓ％以下に低減することが可能となることが判る。 From FIG. 5, the amount of crystal water due to goethite in the high crystal water ore is dehydrated by setting the temperature when processing the high crystal water ore with a crystal water amount of 7.5 mass% to 200 ° C. or higher. It turns out that it becomes possible to reduce to 3 mass% or less.
表１に各温度における飽和水蒸気圧力、飽和水の比体積、粘性率を示す（非特許文献５、参照）。 Table 1 shows the saturated water vapor pressure, the specific volume of saturated water, and the viscosity at each temperature (see Non-Patent Document 5).
［非特許文献５］水熱科学ハンドブック編集委員会編；水熱科学ハンドブック，ｐ６４９−６７９，技報堂出版（２０００） [Non-Patent Document 5] Hydrothermal Science Handbook Editorial Committee Edition; Hydrothermal Science Handbook, p649-679, Gihodo Publishing (2000)
表１に示すように、２５０℃以上の温度では、水の飽和蒸気圧力は、２５０℃で３．９７６２ＭＰａ、３００℃で８．５８７９ＭＰａ、３５０℃で１６．５２９ＭＰａであり、これらの温度における飽和水の比体積はそれぞれ、１．２５１５９ｄｍ3／ｋｇ、１．４０３８ｄｍ3／ｋｇ、１．７４０７ｄｍ3／ｋｇである。 As shown in Table 1, at a temperature of 250 ° C. or higher, the saturated vapor pressure of water is 3.9762 MPa at 250 ° C., 8.5879 MPa at 300 ° C., 16.529 MPa at 350 ° C., and saturated water at these temperatures. the specific volume of each is 1.25159dm 3 /kg,1.4038dm 3 /kg,1.7407dm 3 / kg .
気体の状態方程式によれば、１モルの分子が常温常圧で気体になる場合、約２２．４Ｌとなる。水の分子量は１８、比体積は１ｍＬ／ｇであるから、１モルの水（液体）：１８ｍＬが水蒸気（気体）：２２．４Ｌに変化する際に１２００倍以上の体積膨張が生じる。 According to the equation of state of gas, when 1 mol of a molecule becomes a gas at normal temperature and pressure, it is about 22.4L. Since the molecular weight of water is 18 and the specific volume is 1 mL / g, volume expansion of 1200 times or more occurs when 1 mol of water (liquid): 18 mL changes to water vapor (gas): 22.4 L.
２５０℃以上の処理温度、例えば２５０℃または３５０℃の温度で高結晶水鉄鉱石を加熱脱水処理する場合、２５０℃または３５０℃の温度における飽和水蒸気圧より低い圧力では、鉄鉱石から発生した水は水蒸気（気体）となるから脱水処理の際に１２００倍以上の体積膨張が生じ、鉄鉱石粒子内に亀裂の発生や粉化が生じる。 When heat-dehydrating high crystalline hydrous iron ore at a treatment temperature of 250 ° C. or higher, for example, 250 ° C. or 350 ° C., water generated from iron ore at a pressure lower than the saturated water vapor pressure at a temperature of 250 ° C. or 350 ° C. Since it becomes water vapor (gas), volume expansion of 1200 times or more occurs during the dehydration process, and cracks and pulverization occur in the iron ore particles.
一方、２５０℃または３５０℃の温度で高結晶水鉄鉱石を加熱脱水処理する場合は、その圧力を飽和水蒸気圧以上とすると、鉄鉱石から発生した水は飽和水（液体）の状態にすることができるため、表１に示された飽和水（液体）の比体積から脱水処理の際の体積膨張を１．７４倍程度に抑制することができる。 On the other hand, when heat-dehydrating high-crystal water ore at a temperature of 250 ° C. or 350 ° C., if the pressure is higher than the saturated water vapor pressure, the water generated from the iron ore should be in the state of saturated water (liquid). Therefore, the volume expansion at the time of dehydration can be suppressed to about 1.74 times from the specific volume of saturated water (liquid) shown in Table 1.
また、表１によれば、２５０℃以上の高温で、かつ飽和水蒸気圧以上の高圧で、高結晶水鉄鉱石を加熱脱水処理する場合は、鉄鉱石から発生した水の粘性率を常温時の１／１０以下に低下することができるため、鉄鉱石から水分が容易に脱離し、鉄鉱石粒子内の亀裂の発生を抑制することが可能となる。 Further, according to Table 1, when high-crystal water iron ore is heated and dehydrated at a high temperature of 250 ° C. or higher and a high pressure of saturated water vapor pressure or higher, the viscosity of water generated from the iron ore is Since it can be reduced to 1/10 or less, moisture can be easily desorbed from the iron ore, and the occurrence of cracks in the iron ore particles can be suppressed.
以上の理由から、本発明において、高結晶水鉄鉱石を加熱脱水処理する際に、流体の温度を２５０℃以上とし、かつ圧力を飽和水蒸気圧以上とする。これにより、高結晶水鉄鉱石を加熱脱水処理する際に、脱水に伴う体積膨張を大幅に抑制し、かつ結晶水から生じた水の粘性を低下し、鉄鉱石粒子内の亀裂の発生や、これにともなう圧潰強度の低下、粒度の低下および粉化を抑制することができる。 For the reasons described above, in the present invention, when heat-dehydrating the high crystalline hydrous ore, the temperature of the fluid is set to 250 ° C. or higher, and the pressure is set to the saturated water vapor pressure or higher. As a result, when heat-dehydrating high-crystal hydrous ore, the volume expansion accompanying dehydration is greatly suppressed, and the viscosity of water generated from the crystal water is reduced, the occurrence of cracks in the iron ore particles, Along with this, a reduction in crushing strength, a reduction in particle size and pulverization can be suppressed.
図２に加熱処理する前の鉄鉱石Ａ（ａ）と、電気炉を用いて３５０℃の温度、常圧大気下で加熱処理した後の鉄鉱石Ａ（ｂ）、及び、３５０℃の温度、２０ＭＰａの圧力の水中で加熱処理した後の鉄鉱石Ａ（ｃ）の各組織写真を示す。 The iron ore A (a) before heat treatment in FIG. 2, the temperature of 350 ° C. using an electric furnace, the iron ore A (b) after heat treatment under atmospheric pressure, and the temperature of 350 ° C., The structure | tissue photograph of the iron ore A (c) after heat-processing in the water of a 20 MPa pressure is shown.
図２から、加熱処理する前の鉄鉱石Ａ（ａ）に比べて、３５０℃の温度、常圧大気下で加熱処理した後の鉄鉱石Ａ（ｂ）におけるゲーサイト部には多数の亀裂が発生している。これに対して、３５０℃の温度、２０ＭＰａ（３５０℃の飽和水蒸気圧：１６．５ＭＰａ）の圧力の水中で加熱処理した後の鉄鉱石Ａ（ｃ）におけるゲーサイト部に亀裂の発生は見られず、気孔が多数生成していることがわかる。 From FIG. 2, compared with the iron ore A (a) before heat treatment, there are many cracks in the goethite portion in the iron ore A (b) after heat treatment at a temperature of 350 ° C. and atmospheric pressure. It has occurred. On the other hand, cracks are observed in the goethite portion of iron ore A (c) after heat treatment in water at a temperature of 350 ° C. and a pressure of 20 MPa (saturated water vapor pressure of 350 ° C .: 16.5 MPa). It can be seen that many pores are generated.
図３に加熱処理する前の鉄鉱石Ａ（ａ）と、３５０℃の温度、２０ＭＰａ（３５０℃の飽和水蒸気圧：１６．５ＭＰａ）の圧力の水中で加熱処理した後の鉄鉱石Ａ（ｂ）における気孔径と積算気孔量との関係を示す。 FIG. 3 shows iron ore A (a) before heat treatment, and iron ore A (b) after heat treatment in water at a temperature of 350 ° C. and a pressure of 20 MPa (saturated water vapor pressure of 350 ° C .: 16.5 MPa). 2 shows the relationship between the pore diameter and the cumulative pore volume.
図３から、３５０℃の温度、２０ＭＰａの圧力の水中で加熱処理すると、気孔径５０ｎｍ以下の微細気孔が増加することが判る。鉄鉱石中の気孔径５０ｎｍ以下の微細気孔は、鉄鉱石の圧潰強度を維持しつつ、鉄鉱石の通気性を向上させ、高炉での還元ガスとの還元反応を促進し、焼結時の焼結反応の促進に寄与する。 From FIG. 3, it can be seen that heat treatment in water at a temperature of 350 ° C. and a pressure of 20 MPa increases fine pores having a pore diameter of 50 nm or less. The fine pores with a pore diameter of 50 nm or less in the iron ore improve the air permeability of the iron ore while maintaining the crushing strength of the iron ore, promote the reduction reaction with the reducing gas in the blast furnace, and Contributes to the promotion of the freezing reaction.
以上から、本発明法を用いて、高結晶水鉄鉱石を、２５０℃以上の温度で、かつ飽和水蒸気圧以上の圧力の流体で加熱することにより、鉄鉱石粒子の亀裂や粗大気孔の発生を抑制し、処理後の鉄鉱石の圧潰強度を良好に維持し、かつ粉化を抑制し粒度を良好に維持することができることがわかる。 From the above, by using the method of the present invention, the high crystal hydrous ore is heated with a fluid at a temperature of 250 ° C. or higher and a pressure of the saturated water vapor pressure or higher, thereby causing cracks in iron ore particles and generation of rough atmospheric pores. It can be seen that the crushing strength of the iron ore after treatment can be satisfactorily maintained, and that the pulverization can be suppressed and the particle size can be favorably maintained.
また、加熱脱水処理において、流体として水を用いると、鉄鉱石中にカオリン（非特許文献６、参照）などの粘土鉱物が含有している場合に、２５０℃以上の温度で、かつ飽和水蒸気圧以上の圧力の高温高圧水に溶解するため、処理後の鉄鉱石の鉄純度を向上させることができる。 In addition, when water is used as a fluid in the heat dehydration process, when a clay mineral such as kaolin (see Non-Patent Document 6) is contained in the iron ore, a temperature of 250 ° C. or higher and a saturated water vapor pressure are used. Since it melt | dissolves in the high temperature / high pressure water of the above pressure, the iron purity of the iron ore after a process can be improved.
［非特許文献６］材料とプロセス（ＣＡＭＰ−ＩＳＩＪ）Ｖｏｌ．１６（２００３）ｐ９０９
一般に、カオリン（化学組成Ａｌ2Ｓｉ2Ｏ5（ＯＨ）4）を常圧常温で加熱脱水処理した場合には、４００℃以上の温度で脱水し、Ａｌ2Ｓｉ2Ｏ7の形態でメタカオリン、あるいはムライトとして鉄鉱石中に残存することが知られている。
[Non-Patent Document 6] Materials and Processes (CAMP-ISIJ) Vol. 16 (2003) p909
In general, when kaolin (chemical composition Al 2 Si 2 O 5 (OH) 4 ) is dehydrated by heating at normal pressure and normal temperature, it is dehydrated at a temperature of 400 ° C. or higher, and metakaolin in the form of Al 2 Si 2 O 7 , Or it is known that it remains in iron ore as mullite.
本発明者らは、本発明法によって、２５０℃以上の温度で、かつ飽和水蒸気圧以上の圧力の高温高圧水で処理すると、カオリンの脱水が起きない４００℃以下の温度でも、鉄鉱石中のカオリンが水中に溶解し、その結果、処理後の鉄鉱石中のゲーサイトに起因する結晶水が脱水により減少されるとともに、鉄鉱石中のカオリンに起因するＡｌおよびＳｉの含有量を低減させることができる。 When the present inventors treat with high-temperature high-pressure water at a temperature of 250 ° C. or higher and a pressure of saturated water vapor pressure or higher by the method of the present invention, even in a temperature of 400 ° C. or lower at which kaolin does not dehydrate, Kaolin dissolves in water, and as a result, crystal water caused by goethite in iron ore after treatment is reduced by dehydration, and the contents of Al and Si caused by kaolin in iron ore are reduced. Can do.
図４に加熱処理する前の鉄鉱石Ｂ（ａ）と、３５０℃の温度で、２０ＭＰａの圧力の水中で加熱処理した鉄鉱石Ｂ（ｂ）の各赤外吸収スペクトルを示す。 FIG. 4 shows each infrared absorption spectrum of iron ore B (a) before heat treatment and iron ore B (b) heat-treated in water at a pressure of 20 MPa at a temperature of 350.degree.
図４から、加熱処理する前に比べて、３５０℃の温度、２０ＭＰａの圧力の水中で加熱処理した後の鉄鉱石中のカオリンに起因する赤外吸収ピーク、および、ゲーサイトに起因する赤外吸収ピークの強度が何れも小さくなっている。 From FIG. 4, compared to before heat treatment, infrared absorption peak due to kaolin in iron ore after heat treatment in water at a temperature of 350 ° C. and a pressure of 20 MPa, and infrared due to goethite The intensity of each absorption peak is small.
鉄鉱石中のカオリンはＡｌおよびＳｉを主体とするため、焼結反応における融液の融点を上昇する結果、焼結反応を阻害し、焼結鉱の生産性と成品歩留を低下する原因となる。 Kaolin in iron ore is mainly composed of Al and Si. As a result, the melting point of the melt in the sintering reaction is increased. As a result, the sintering reaction is hindered and the productivity and product yield of the sintered ore are reduced. Become.
本発明において、３５０℃の温度、２０ＭＰａの圧力で加熱処理する際に流体として水を用いることにより、鉄鉱石中のゲーサイトに起因する結晶水量が減少されるとともに、鉄鉱石中のカオリン量を低減させることができるため、焼結工程での焼成反応を促進させ、焼結鉱の生産性及び成品歩留の向上することが可能となる。この理由から、本発明の高結晶水鉄鉱石の処理において流体として水を用いることが好ましい。 In the present invention, by using water as a fluid when heat-treating at a temperature of 350 ° C. and a pressure of 20 MPa, the amount of crystal water caused by goethite in the iron ore is reduced, and the amount of kaolin in the iron ore is reduced. Since it can be reduced, the firing reaction in the sintering process can be promoted, and the productivity of the sintered ore and the product yield can be improved. For this reason, it is preferable to use water as the fluid in the treatment of the high crystallinity iron ore of the present invention.
［実施例１］
粒径２〜２．８ｍｍの鉄鉱石Ａ、Ｂ、Ｃの３種類について、各種条件で処理をした後、結晶水量、圧潰強度、気孔量、及び、２ｍｍ以上粒子の歩留を比較評価した。その結果を表２に示す。
[Example 1]
Three types of iron ores A, B, and C having a particle size of 2 to 2.8 mm were treated under various conditions, and then the amount of crystal water, crushing strength, the amount of pores, and the yield of particles of 2 mm or more were compared and evaluated. The results are shown in Table 2.
本発明の実施例は何れも、処理後の鉄鉱石中の結晶水量を３ｍａｓｓ％以下に低減することができ、処理前の鉄鉱石に比べて処理後の鉄鉱石の圧潰強度低下を２割程度に抑えつつ、気孔量を約３倍まで増加させることができた。 In any of the examples of the present invention, the amount of water of crystallization in the iron ore after the treatment can be reduced to 3 mass% or less, and the reduction in the crushing strength of the iron ore after the treatment is about 20% compared to the iron ore before the treatment. It was possible to increase the amount of pores up to about 3 times.
比較例では、流体は全て気体であり、結晶水は低減できるものの、圧潰強度は１／３に低下した。気孔量は、見かけ上増加するが、粉化が著しく粒子としての歩留まりは実施例の７割程度であった。 In the comparative example, the fluid was all a gas, and although the crystal water could be reduced, the crushing strength was reduced to 1/3. Although the amount of pores seemed to increase, powdering was remarkable and the yield as particles was about 70% of the example.
［実施例２］
表１に示した流体として水を用いて３５０℃の温度、２０MPａの圧力で処理した実施例３及び６について、本発明の処理前と処理後の化学分析を実施した。その結果を表３に示す。
[Example 2]
Chemical analysis before and after the treatment of the present invention was carried out on Examples 3 and 6 treated with water as a fluid shown in Table 1 at a temperature of 350 ° C. and a pressure of 20 MPa. The results are shown in Table 3.
鉄鉱石Ａはカオリンをほとんど含まない鉄鉱石であり、鉄鉱石Ｂはカオリン量が６．４ｍａｓｓ％の鉄鉱石である。 The iron ore A is an iron ore containing almost no kaolin, and the iron ore B is an iron ore having a kaolin amount of 6.4 mass%.
カオリンをほとんど含まない鉄鉱石Ａを３５０℃の温度、２０MPａの圧力の水で処理する場合は、鉄鉱石中のゲーサイトの結晶水が脱水されるため、その脱水による質量減少分だけ、処理後の鉄鉱石中のT.Fe、T.Si及びT.Alの量が増加している。なお、この場合、Feに対するAl、Siの元素比は変化していない。 When iron ore A containing almost no kaolin is treated with water at a temperature of 350 ° C. and a pressure of 20 MPa, the crystal water of goethite in the iron ore is dehydrated. The amount of T.Fe, T.Si, and T.Al in the iron ore is increasing. In this case, the element ratio of Al and Si to Fe is not changed.
一方、カオリン量が６．４ｍａｓｓ％の鉄鉱石Bを３５０℃の温度、２０MPａの圧力の水で処理する場合は、鉄鉱石中のゲーサイトの結晶水が脱水されると共に、鉄鉱石中のカオリン（化学組成Ａｌ2Ｓｉ2Ｏ5（ＯＨ）4）が水中に溶解する。このため、結晶水の脱水による質量減少分と、カオリンの溶解により、処理後の鉄鉱石中のT.Feが増加し、Al、及び、Siの量が減少する。 On the other hand, when iron ore B with a kaolin content of 6.4 mass% is treated with water at a temperature of 350 ° C. and a pressure of 20 MPa, the crystal water of goethite in the iron ore is dehydrated and the kaolin in the iron ore is dehydrated. (Chemical composition Al 2 Si 2 O 5 (OH) 4 ) dissolves in water. For this reason, T.Fe in the iron ore after processing increases and the amounts of Al and Si decrease due to the decrease in mass due to dehydration of crystal water and dissolution of kaolin.
これらの結果から、ゲーサイトとともにカオリンを含有する鉄鉱石を加熱脱水処理し、鉄鉱石からゲーサイトの結晶水とカオリンを脱離するためには、流体として水を用いることが好ましいことが判る。 From these results, it can be seen that it is preferable to use water as a fluid in order to heat and dehydrate iron ore containing kaolin together with goethite and desorb goethite crystal water and kaolin from the iron ore.
１ 流体容器
２ 昇圧装置
３ 圧力容器
４ 加熱炉
５ 背圧調整器
６ 圧力計
７ 熱伝対
DESCRIPTION OF SYMBOLS 1 Fluid container 2 Booster 3 Pressure vessel 4 Heating furnace 5 Back pressure regulator 6 Pressure gauge 7 Thermocouple
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