JP7476871B2 - Metal manufacturing methods - Google Patents

Metal manufacturing methods Download PDF

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JP7476871B2
JP7476871B2 JP2021194222A JP2021194222A JP7476871B2 JP 7476871 B2 JP7476871 B2 JP 7476871B2 JP 2021194222 A JP2021194222 A JP 2021194222A JP 2021194222 A JP2021194222 A JP 2021194222A JP 7476871 B2 JP7476871 B2 JP 7476871B2
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和哉 南谷
憲治 中瀬
由枝 中井
直樹 菊池
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JFE Steel Corp
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Description

本発明は、金属製錬用または金属精錬用の主原料もしくは副原料として用いられるリンを含有する金属酸化物から、リン濃度の低い金属を製造する方法に関する。 The present invention relates to a method for producing metals with low phosphorus concentrations from phosphorus-containing metal oxides that are used as a main or auxiliary raw material for metal smelting or refining.

近年、製鉄業における冷鉄源の使用拡大の需要が高まっている。循環型社会の構築のために、鉄源リサイクルは必要不可欠であるうえ、昨今のCO削減の需要からも冷鉄源使用量増大は不可欠である。冷鉄源は酸化鉄(Fe)である鉄鉱石と異なり、溶製プロセスに還元工程を要さないためCO排出量の低減が可能であり、冷鉄源の使用量は増加の一途をたどっている。 In recent years, the demand for expanded use of cold iron ore in the steel industry has been increasing. In order to build a recycling-oriented society, recycling of iron ore is essential, and the recent demand for reducing CO2 emissions also necessitates an increase in the use of cold iron ore. Unlike iron ore, which is iron oxide ( Fe2O3 ), cold iron ore does not require a reduction process in the smelting process, making it possible to reduce CO2 emissions, and the use of cold iron ore is steadily increasing.

高炉-転炉法は原料である鉄鉱石(Fe)を還元材であるコークスとともに高炉へ装入、C濃度が4.5-5.0%程度の溶銑を溶製し、その溶銑を転炉に装入して不純物成分であるC、Si、Pなどを酸化除去する製鋼プロセスである。高炉での溶銑製造時には鉄鉱石の還元などのために溶銑1トンあたり、500kg程度の炭素源を必要とし、約2トン程度のCOガスが発生する。一方、冷鉄源、たとえば、鉄スクラップを原料として溶鋼を製造する場合には、鉄鉱石の還元に必要とされる炭素源が不要となる。したがって、鉄スクラップを溶解するために必要なエネルギーを考慮しても、1トンの溶銑を1トンの鉄スクラップに置き換えることで、約1.5トンのCOガス削減につながる。上記のことから、温室効果ガスの排出量の削減と生産活動の維持の両立のためには冷鉄源の使用量を増やしていくことが必要である。 The blast furnace-converter process is a steelmaking process in which iron ore (Fe 2 O 3 ), a raw material, is charged into a blast furnace together with coke, a reducing agent, to produce molten pig iron with a C concentration of about 4.5-5.0%, and the molten pig iron is charged into a converter to oxidize and remove impurities such as C, Si, and P. When producing molten pig iron in a blast furnace, about 500 kg of carbon source is required per ton of molten pig iron for the reduction of iron ore, and about 2 tons of CO 2 gas is generated. On the other hand, when molten steel is produced using a cold iron source, for example, iron scrap, as a raw material, the carbon source required for the reduction of iron ore is not required. Therefore, even when the energy required to melt iron scrap is taken into consideration, replacing 1 ton of molten pig iron with 1 ton of iron scrap leads to a reduction of about 1.5 tons of CO 2 gas. From the above, it is necessary to increase the amount of cold iron source used in order to reduce greenhouse gas emissions and maintain production activities at the same time.

しかし、鉄スクラップ、特に高級鋼製造に不可欠な高品位の鉄スクラップの需給が逼迫していることから、冷鉄源としてスクラップに換えて還元鉄のニーズが高まっている。還元鉄は鉄鉱石を還元して製造され、高炉-転炉法の様に生成した鉄中のC濃度を高位とする必要がない。還元剤として、過剰なC源を使用しない分、鉄1トン当たり約0.2トンのCOガス低減につながる。また、還元剤をC源でなく、水素または天然ガス等の炭化水素系ガスとすることで、更なるCO排出量の低減も可能である。 However, due to the tight supply and demand of iron scrap, especially high-quality iron scrap that is essential for the production of high-grade steel, there is an increasing need for reduced iron to replace scrap as a cold iron source. Reduced iron is produced by reducing iron ore, and there is no need to increase the C concentration in the produced iron as in the blast furnace-converter process. Since no excessive C source is used as a reducing agent, this leads to a reduction in CO2 gas of about 0.2 tons per ton of iron. In addition, by using a hydrocarbon gas such as hydrogen or natural gas as the reducing agent instead of a C source, it is possible to further reduce CO2 emissions.

還元鉄を使用する際の課題として、還元鉄に含有されるリンが高位であることが挙げられる。鉄鋼製品中のリンは熱間脆性などの品質低下を及ぼすため、要求品質に応じたリン濃度まで低減する必要がある。電気炉法で還元鉄を溶解して溶鋼を製造する場合には、還元鉄中のリンの大部分が溶鋼中に入る(復リンともいう)。そのため、現状の還元鉄は鉄鉱石中のリン濃度が低い高品位鉄鉱石(リン濃度約0.01質量%)により製造され、還元鉄としてのリン濃度は約0.02質量%程度である。 One of the challenges in using reduced iron is that it contains a high level of phosphorus. Phosphorus in steel products can cause quality problems such as hot brittleness, so the phosphorus concentration must be reduced to a level appropriate for the required quality. When reduced iron is melted to produce molten steel using an electric furnace, most of the phosphorus in the reduced iron ends up in the molten steel (also known as rephosphorization). For this reason, currently reduced iron is produced from high-grade iron ore with a low phosphorus concentration (phosphorus concentration of approximately 0.01% by mass), and the phosphorus concentration of the reduced iron is approximately 0.02% by mass.

一方で、リン濃度が低い高品位鉄鉱石の枯渇が予想されており、今後はリン濃度の高い低品位鉄鉱石を使用した還元鉄を原料とした溶鋼製造が求められる。現行の高炉法で使用されている鉄鉱石中のリン濃度は0.05~0.10質量%(還元鉄としてのリン濃度に換算すると0.10~0.15質量%)であり、今後更なるリン濃度増加が予想されている。このリン濃度は前記リン濃度が低い高品位鉄鉱石で製造した還元鉄のリン濃度の5~10倍以上である。このような還元鉄を用いて、鉄鋼製品中のリンによる品質低下を防ぐためには、リン濃度が高い還元鉄を溶解して溶鋼を製造する際にリン除去するか、リン濃度の高い鉄鉱石から還元鉄を製造する際にリン除去する必要がある。このようなリン除去に関し、いくつかの技術が提案されている。 On the other hand, it is predicted that high-grade iron ore with a low phosphorus concentration will be depleted, and in the future, it will be necessary to produce molten steel using reduced iron made from low-grade iron ore with a high phosphorus concentration. The phosphorus concentration in iron ore used in the current blast furnace method is 0.05 to 0.10 mass% (0.10 to 0.15 mass% when converted to the phosphorus concentration as reduced iron), and it is predicted that the phosphorus concentration will increase further in the future. This phosphorus concentration is 5 to 10 times or more than the phosphorus concentration of reduced iron produced from the high-grade iron ore with a low phosphorus concentration. In order to prevent the quality degradation caused by phosphorus in steel products using such reduced iron, it is necessary to remove phosphorus when melting reduced iron with a high phosphorus concentration to produce molten steel, or to remove phosphorus when producing reduced iron from iron ore with a high phosphorus concentration. Several technologies have been proposed for removing phosphorus.

特許文献1には、リン含有量の高い鉄鉱石を0.5mm以下に粉砕しこれに水を加えてパルプ濃度35mass%前後とし、溶剤にHSOまたはHClを添加しpH2.0以下で反応させてリン鉱物を分解溶出し、ついで磁力選別により磁鉄鉱等の磁着物を採取することで、非磁着物たるSiOやAl等をスライムとして沈降分離すると共に、このとき液中に溶出したPを消石灰または生石灰を添加してpH5.0~10.0の範囲内で中和してリン酸カルシウムとして分離回収する方法が提案されている。 Patent Document 1 proposes a method in which iron ore with a high phosphorus content is crushed to 0.5 mm or less, water is added to this to make the pulp concentration about 35 mass%, H 2 SO 4 or HCl is added as a solvent and reacted at pH 2.0 or less to decompose and dissolve phosphorus minerals, and then magnetized materials such as magnetite are collected by magnetic separation, and non-magnetic materials such as SiO 2 and Al 2 O 3 are precipitated and separated as slime, and P dissolved in the liquid at this time is neutralized to a pH range of 5.0 to 10.0 by adding slaked lime or quicklime, and separated and recovered as calcium phosphate.

また、特許文献2には、鉄鉱石を還元する際に金属鉄が生成しない条件でリンを還元し気化除去を行った後、金属鉄まで還元する方法が提案されている。 Patent Document 2 also proposes a method of reducing iron ore under conditions in which metallic iron is not produced, and then vaporizing and removing phosphorus, and then reducing the phosphorus to metallic iron.

また、特許文献3には、リン含有物質を窒素含有ガスと反応させることでリンを除去する方法が提案されている。 Patent Document 3 also proposes a method for removing phosphorus by reacting a phosphorus-containing substance with a nitrogen-containing gas.

特開昭60-261501号公報Japanese Patent Application Laid-Open No. 60-261501 特開2020-20010号公報JP 2020-20010 A 国際公開第2019/131128号International Publication No. 2019/131128

しかしながら、上記従来技術には以下の問題がある。
特許文献1の技術では酸を用いた湿式処理であり、回収した磁着物を主原料として利用するための乾燥に時間とコストがかかるという課題がある。また、事前に0.5mm以下に粉砕するのに時間とコストを要するという課題もある。
However, the above-mentioned conventional techniques have the following problems.
The technology of Patent Document 1 involves a wet treatment using an acid, and there are problems in that it takes time and costs to dry the recovered magnetized material in order to use it as a main raw material, and there are also problems in that it takes time and costs to crush the material into particles of 0.5 mm or less in advance.

特許文献2の方法は、鉱石中にアパタイトCa(PO)(F,OH)、ストレンジャイトFe(PO)・2(HO)、ウェイベライトAl(PO(F,OH)・5HO等様々な化学形態で存在するリンを還元する必要があるため、脱リン工程での脱リン率が40~60%と低いという課題がある。 The method of Patent Document 2 requires the reduction of phosphorus that exists in the ore in various chemical forms, such as apatite Ca 5 (PO 4 ) (F, OH), strengite Fe (PO 4 ) · 2 (H 2 O), and weaverite Al 3 (PO 4 ) 2 (F, OH) 3 · 5H 2 O, and therefore has the problem that the dephosphorization rate in the dephosphorization process is low at 40 to 60%.

特許文献3の方法は、金属が生成しない温度、酸素分圧での処理であり、リンを除去した後の酸化物を再還元して金属化する必要があるという課題がある。 The method of Patent Document 3 involves treatment at a temperature and oxygen partial pressure at which metals are not produced, and has the problem that the oxides after phosphorus removal must be re-reduced to metallize them.

本発明は、このような事情に鑑みてなされたものであって、その目的とするところは、湿式処理を行わず、金属製錬用または金属精錬用の主原料もしくは副原料として用いられるリンを含有する金属酸化物から、一段階の還元処理によってリンを短時間かつ低コストで効果的に低減させるための、金属酸化物からリン濃度の低い金属を製造する方法を提案することである。 The present invention was made in view of the above circumstances, and its purpose is to propose a method for producing a metal with a low phosphorus concentration from a metal oxide, which is used as a main or auxiliary raw material for metal smelting or refining and contains phosphorus, by a one-stage reduction process, in a short time and at low cost, without performing wet processing.

発明者らは、従来技術が抱えている前述の課題について検討する中で、リン含有物質を低温加熱して窒素含有ガスと接触させることでリンの除去が効率的に行われることを突き止め、本発明を開発するに至った。上記課題を有利に解決する本発明にかかる金属の製造方法は、金属製錬用または金属精錬用の主原料もしくは副原料として用いられるリンを含有する金属酸化物を、温度、酸素分圧、および窒素分圧の調整下で窒素を含有する還元性ガスと反応させ、前記金属酸化物中のリンを気体として除去しつつ前記金属酸化物を還元する還元処理を行なって金属を生成するものである。 In the course of studying the above-mentioned problems of the prior art, the inventors discovered that phosphorus can be removed efficiently by heating a phosphorus-containing substance at a low temperature and contacting it with a nitrogen-containing gas, and developed the present invention. The metal production method of the present invention, which advantageously solves the above problems, involves reacting a phosphorus-containing metal oxide used as a main or auxiliary raw material for metal smelting or metal refining with a nitrogen-containing reducing gas under adjustment of temperature, oxygen partial pressure, and nitrogen partial pressure, and performing a reduction process that reduces the metal oxide while removing the phosphorus in the metal oxide as a gas, thereby producing a metal.

なお、本発明にかかる金属の製造方法は、
(ア)前記金属酸化物の融点をTm(℃)として、前記処理温度T(℃)を750℃以上0.95×Tm(℃)以下の範囲とし、前記還元性ガスの前記酸素分圧PO2(atm)を下記(1)式の条件を満たす範囲とし、前記還元性ガスの前記窒素分圧PN2(atm)を0.2atm以上0.9atm以下の範囲として、前記還元処理を行なうこと、
(イ)前記還元性ガスの前記酸素分圧PO2(atm)をCO分圧PCO(atm)とCO分圧PCO2(atm)との比PCO/PCO2により調整すること、
(ウ)前記還元性ガスは、COを含み、CO分圧PCO(atm)は前記窒素分圧PN2(atm)との関係で下記(2)式の条件を満たすこと、
(エ)前記還元性ガスの前記酸素分圧PO2(atm)をH分圧PH2(atm)とHO分圧PH2O(atm)との比PH2/PH2Oにより調整すること、
(オ)前記還元性ガスは、Hを含み、H分圧PH2(atm)は前記窒素分圧PN2(atm)との関係で下記(3)式の条件を満たすこと、
(カ)前記金属酸化物が鉄鉱石またはマンガン鉱石であること、
などが好ましい解決手段になり得るものと考えられる。
[式1]
logPO2≦-1.45×10-5+0.0479T-48.2 (1)
[式2]
(-2.35×10-7+3.88×10-4T+0.587)(1-PN2)≦PCO (2)
[式3]
(-1.31×10-8-8.85×10-4T+0.777)(1-PN2)≦PH2 (3)
The method for producing a metal according to the present invention is as follows:
(A) performing the reduction treatment at a treatment temperature T (°C) in the range of 750°C or more and 0.95×Tm (°C) or less, where Tm (°C) is the melting point of the metal oxide; at a partial oxygen pressure P O2 (atm) of the reducing gas in the range satisfying the condition of the following formula (1); and at a partial nitrogen pressure P N2 (atm) of the reducing gas in the range of 0.2 atm or more and 0.9 atm or less;
(a) adjusting the oxygen partial pressure P O2 (atm) of the reducing gas by adjusting the ratio P CO /P CO2 of the CO partial pressure P CO (atm) to the CO2 partial pressure P CO2 ( atm);
(c) the reducing gas contains CO, and the CO partial pressure P CO (atm) satisfies the condition of the following formula (2) in relation to the nitrogen partial pressure P N2 (atm);
(d) adjusting the oxygen partial pressure P O2 (atm) of the reducing gas by adjusting the ratio P H2 /P H2O of the H2 partial pressure P H2 (atm) and the H2O partial pressure P H2O ( atm ) ;
(E) the reducing gas contains H2 , and the H2 partial pressure P H2 (atm) satisfies the condition of the following formula (3) in relation to the nitrogen partial pressure P N2 (atm);
(F) the metal oxide is iron ore or manganese ore;
This is thought to be a preferable solution.
[Formula 1]
logP O2 ≦−1.45×10 −5 T 2 +0.0479T−48.2 (1)
[Formula 2]
(-2.35 x 10-7T2 +3.88 x 10-4T +0.587) (1- P N2 ) ≤ P CO (2)
[Formula 3]
(-1.31 x 10-8T2-8.85 x 10-4T + 0.777) (1-P N2 ) ≦ P H2 (3)

本発明によれば、金属製錬または金属精錬用原料である、リンを含有する主原料もしくは副原料などの固体すなわちリン含有物質に対し、そのリン含有物質の融点未満の処理温度に加熱して窒素含有ガスと反応させることにより、該リン含有物質中のリンを窒化ガスとして直接除去することが可能になるので、金属製錬ないし金属精錬プロセス内の脱リン処理プロセス負荷が低減でき、溶解することで溶鋼の原料として用いることができる。 According to the present invention, by heating a solid, i.e., phosphorus-containing substance, such as a phosphorus-containing main raw material or auxiliary raw material that is a raw material for metal smelting or metal refining, to a processing temperature below the melting point of the phosphorus-containing substance and reacting it with a nitrogen-containing gas, it is possible to directly remove the phosphorus from the phosphorus-containing substance as a nitriding gas, thereby reducing the load of the dephosphorization process in the metal smelting or metal refining process, and by melting it, it can be used as a raw material for molten steel.

さらに、本発明によれば、窒化除去されたリンは排ガス中で酸化されてPとなり、リン濃度の高いダストを回収することができるようになるので、リン資源として有効活用が可能になるという副次的効果もある。 Furthermore, according to the present invention, the phosphorus removed by nitriding is oxidized in the exhaust gas to become P2O5 , and dust with a high phosphorus concentration can be recovered, which has the secondary effect of making it possible to effectively utilize it as a phosphorus resource.

リンをPNの気体として除去する反応(a)、酸化鉄から金属鉄への還元反応(b)および、固体炭素と一酸化炭素ガスの平衡反応(c)について、それぞれの反応の平衡が成り立つときの温度(T)と酸素分圧(logPO2)の関係を示すグラフである。1 is a graph showing the relationship between temperature (T) and oxygen partial pressure (logP O2 ) when equilibrium is achieved for each of the following reactions: (a) the reaction to remove phosphorus as PN gas, (b) the reduction reaction of iron oxide to metallic iron, and (c) the equilibrium reaction of solid carbon and carbon monoxide gas. 処理温度T=1000℃における鉄鉱石のリン除去率(ΔP)と窒素分圧(PN2)との関係を示すグラフである。1 is a graph showing the relationship between the phosphorus removal rate (ΔP) of iron ore and the nitrogen partial pressure (P N2 ) at a treatment temperature T=1000° C.; 処理温度T=1000℃における鉄鉱石の金属化率と窒素分圧(PN2)との関係を示すグラフである。1 is a graph showing the relationship between the metallization rate of iron ore and the nitrogen partial pressure (P N2 ) at a treatment temperature T=1000° C.; CO=0.1atmおよびPN2=0.9atmにおける鉄鉱石のリン除去率(ΔP)と処理温度(T)の関係を示すグラフである。1 is a graph showing the relationship between phosphorus removal rate (ΔP) from iron ore and processing temperature (T) at P CO =0.1 atm and P N2 =0.9 atm. CO=0.1atmおよびPN2=0.9atmにおける鉄鉱石の金属化率と処理温度(T)の関係を示すグラフである。1 is a graph showing the relationship between the metallization rate of iron ore and the processing temperature (T) at P CO =0.1 atm and P N2 =0.9 atm. 表2、3に示した処理温度T=1000℃における一酸化炭素分圧(PCO)と窒素分圧(PN2)とがリン除去率に与える影響を示すグラフである。1 is a graph showing the influence of carbon monoxide partial pressure (P CO ) and nitrogen partial pressure (P N2 ) on the phosphorus removal rate at a treatment temperature T of 1000° C. shown in Tables 2 and 3. 表2、3に示した処理温度T=800℃における一酸化炭素分圧(PCO)と窒素分圧(PN2)とがリン除去率に与える影響を示すグラフである。1 is a graph showing the influence of carbon monoxide partial pressure (P CO ) and nitrogen partial pressure (P N2 ) on the phosphorus removal rate at a treatment temperature T of 800° C. shown in Tables 2 and 3. 表2、3に示した処理温度T=1200℃における一酸化炭素分圧(PCO)と窒素分圧(PN2)とがリン除去率に与える影響を示すグラフである。1 is a graph showing the influence of carbon monoxide partial pressure (P CO ) and nitrogen partial pressure (P N2 ) on the phosphorus removal rate at a treatment temperature T of 1200° C. shown in Tables 2 and 3. 表4に示した処理温度T=1000℃における水素分圧(PH2)と窒素分圧(PN2)とがリン除去率に与える影響を示すグラフである。1 is a graph showing the effect of hydrogen partial pressure (P H2 ) and nitrogen partial pressure (P N2 ) on the phosphorus removal rate at a treatment temperature T=1000° C. shown in Table 4. 表5に示した処理温度T=800℃における水素分圧(PH2)と窒素分圧(PN2)とがリン除去率に与える影響を示すグラフである。1 is a graph showing the effect of hydrogen partial pressure (P H2 ) and nitrogen partial pressure (P N2 ) on the phosphorus removal rate at a treatment temperature T=800° C. shown in Table 5. 表6に示した処理温度T=1200℃における水素分圧(PH2)と窒素分圧(PN2)とがリン除去率に与える影響を示すグラフである。1 is a graph showing the effect of hydrogen partial pressure (P H2 ) and nitrogen partial pressure (P N2 ) on the phosphorus removal rate at a treatment temperature T of 1200° C. shown in Table 6.

以下、本発明の実施の形態について具体的に説明する。なお、以下の実施形態は、本発明の技術的思想を具体化するための方法を例示するものであり、構成を下記のものに特定するものでない。すなわち、本発明の技術的思想は、特許請求の範囲に記載された技術的範囲内において、種々の変更を加えることができる。 The following is a detailed description of the embodiments of the present invention. Note that the following embodiments are merely examples of methods for realizing the technical idea of the present invention, and do not limit the configuration to that described below. In other words, the technical idea of the present invention can be modified in various ways within the technical scope described in the claims.

本発明の開発にあたり、発明者らは、金属製錬や金属精錬の主原料および副原料として、リン濃度が高く安価な物質に着目し、そうしたリン含有物質からリンを予め除去する方法について研究をすすめた。 In developing this invention, the inventors focused on inexpensive substances with high phosphorus concentrations as main and secondary raw materials for metal smelting and refining, and conducted research into methods for removing phosphorus from such phosphorus-containing substances in advance.

金属製錬や金属精錬用原料(主原料および副原料)として用いられる前記リン含有物質は、そのリンを主としてPの如き酸化物として含有しており、その他にCaOやSiO、MgO、Al、MnO、Mn、FeO、Feなどの金属酸化物が含まれているのが普通である。こうした金属製錬や金属精錬用原料、とくに製鉄用原料としては、例えば、鉄鉱石やマンガン鉱石がある。 The phosphorus-containing substances used as raw materials (main raw materials and auxiliary raw materials) for metal smelting and metal refining contain phosphorus mainly in the form of oxides such as P 2 O 5 , and generally also contain metal oxides such as CaO, SiO 2 , MgO, Al 2 O 3 , MnO, Mn 2 O 3 , FeO, and Fe 2 O 3. Examples of such raw materials for metal smelting and metal refining, particularly raw materials for steelmaking, include iron ore and manganese ore.

このように、金属製錬や金属精錬の主原料および副原料(以下は、「製鉄用原料」の例で説明する)は、様々な金属酸化物によって構成されている。ところで、前記リンは、カルシウム(Ca)および珪素(Si)と比較して酸素との親和力が弱いことから、リン含有物質を、炭素、珪素、アルミニウムなどを使って還元した場合、リン含有物質中のPは容易に還元されることが知られている。一方で、多くの製鉄用原料中には、鉄がFeOやFeの形態の酸化物(以下、まとめて「FexO」と記す)で含有しており、これらの鉄酸化物は酸素との親和力がリンと同等であることから、リン含有物質を、炭素や珪素、アルミニウムなどで還元すると、同時にFexOも還元されることになる。なお、マンガンはMnOやMnあるいはMnOの形態の酸化物(以下、まとめて「MnxO」と記す)の形で含有している。そのマンガンの酸化物は、酸素との親和力がリンよりも強く、炭素や珪素、アルミニウムなどよりは弱いため、これらの物質で還元すると、リンと同時にMnxOも還元されてしまう。 Thus, the main raw materials and auxiliary raw materials (hereinafter, the example of "raw materials for iron making") for metal smelting and metal refining are composed of various metal oxides. Since phosphorus has a weak affinity for oxygen compared with calcium (Ca) and silicon (Si), it is known that when a phosphorus-containing material is reduced using carbon, silicon, aluminum, or the like, P 2 O 5 in the phosphorus-containing material is easily reduced. On the other hand, many raw materials for iron making contain iron in the form of oxides in the form of FeO or Fe 2 O 3 (hereinafter, collectively referred to as "FexO"), and since these iron oxides have the same affinity for oxygen as phosphorus, when a phosphorus-containing material is reduced using carbon, silicon, aluminum, or the like, FexO is also reduced at the same time. Note that manganese is contained in the form of oxides in the form of MnO, Mn 2 O 3 , or MnO 2 (hereinafter, collectively referred to as "MnxO"). The manganese oxide has a stronger affinity for oxygen than phosphorus but a weaker affinity than carbon, silicon, aluminum, etc., so when it is reduced by these substances, MnxO is reduced at the same time as phosphorus.

ただ、リンは金属鉄あるいは金属マンガン中への溶解度が高く、とくに還元により生成したリンは、還元により生成した金属鉄あるいは金属マンガン中に迅速に溶解し、高リン含有鉄あるいは高リン含有マンガンとなる。このように、還元によるリンの除去方法は、有価成分である鉄やマンガンへのリンの吸着、溶解が生じるため、リン除去率が低いという課題がある。 However, phosphorus has a high solubility in metallic iron or metallic manganese, and the phosphorus produced by reduction in particular dissolves quickly in the metallic iron or manganese produced by reduction, resulting in high-phosphorus iron or manganese. Thus, the method of removing phosphorus by reduction has the problem of a low phosphorus removal rate, since phosphorus is adsorbed and dissolved by the valuable components iron and manganese.

発明者らは、この問題を解決すべく鋭意研究を重ねた結果、リンを一窒化リン(PN)の気体として除去することにより、金属鉄へのリンの吸着を抑制しつつ金属を生成することが可能であることを見出した。即ち、発明者らは、リン含有物質中にPとして存在するリンを、一窒化リン(PN)の気体として除去する下記の化学式1に示す反応(a)と、リン含有物質に含まれる鉄酸化物が還元されて金属鉄となる下記の化学式2に示す反応(b)がともに進行する領域が存在することを熱力学検討により確認したのである。 The inventors have conducted extensive research to solve this problem, and as a result have found that it is possible to produce a metal while suppressing the adsorption of phosphorus to metallic iron by removing phosphorus as phosphorus mononitride (PN) gas. That is, the inventors have confirmed through thermodynamic studies that there exists a region in which both reaction ( a ) shown in the following chemical formula 1, in which phosphorus present as P2O5 in a phosphorus-containing substance is removed as phosphorus mononitride (PN) gas, and reaction (b) shown in the following chemical formula 2, in which iron oxide contained in the phosphorus-containing substance is reduced to metallic iron, proceed.

Figure 0007476871000001
Figure 0007476871000001

Figure 0007476871000002
Figure 0007476871000002

化学式1および2の上記反応(a)および(b)について、平衡が成り立つときの温度と酸素分圧の関係を図1に示す。この図1には比較のために、固体炭素と一酸化炭素ガスの平衡(下記化学式3に示す反応(c))により達成可能な温度Tと酸素分圧PO2の関係を併せて示した。ここで、P活量を0.001、N分圧を0.9atm、PN分圧を0.001atmとした。 The relationship between temperature and oxygen partial pressure when equilibrium is established for the above reactions (a) and (b) of chemical formulas 1 and 2 is shown in Figure 1. For comparison, Figure 1 also shows the relationship between temperature T and oxygen partial pressure P O2 that can be achieved by the equilibrium between solid carbon and carbon monoxide gas (reaction (c) shown in chemical formula 3 below). Here, the P 2 O 5 activity was 0.001, the N 2 partial pressure was 0.9 atm, and the PN partial pressure was 0.001 atm.

Figure 0007476871000003
Figure 0007476871000003

図1において、反応(a)および(b)それぞれの線より下側の温度T(℃)と酸素分圧PO2(atm)の領域において、反応(a)および(b)がそれぞれ右側に進行する。つまり、反応(a)のリン窒化除去および反応(b)による金属鉄の生成が進行するのは、反応(a)および(b)の線の下側の共通部分であり、800℃では酸素分圧PO2を1.11×10-19atm以下、1000℃では1.20×10-15atm以下、1200℃では1.04×10-12atm以下の酸素分圧PO2とすればよい。 1, in the regions of temperature T (°C) and oxygen partial pressure P O2 (atm) below the respective lines of reactions (a) and (b), reactions (a) and (b) proceed to the right. In other words, the removal of phosphorus nitriding in reaction (a) and the production of metallic iron in reaction (b) proceed in the common portion below the lines of reactions (a) and (b), and the oxygen partial pressure P O2 may be set to 1.11×10 −19 atm or less at 800°C, 1.20×10 −15 atm or less at 1000°C, and 1.04×10 −12 atm or less at 1200 °C.

ここで、酸素分圧PO2を低減させるためには、酸化物として安定な元素、例えばCなどの単体を共存させる、あるいはCO、Hなどの還元性ガスと共存させることが有効である。図1の記載からわかるように、724℃以上の温度Tにおいて、固体炭素と一酸化炭素ガスの平衡により達成される酸素分圧PO2は、リンの窒化除去反応(a)および金属鉄生成反応(b)を進行させるのに十分な値となる。また、還元ガスを供給する場合には均一に供給することが容易であるという利点がある。 Here, in order to reduce the oxygen partial pressure P O2 , it is effective to make a stable element as an oxide, for example, a simple substance such as C, coexist with the catalyst, or to make it coexist with a reducing gas such as CO or H 2. As can be seen from Fig. 1, at a temperature T of 724°C or higher, the oxygen partial pressure P O2 achieved by the equilibrium between solid carbon and carbon monoxide gas is a value sufficient to advance the nitriding reaction of phosphorus (a) and the metallic iron production reaction (b). In addition, when a reducing gas is supplied, it has the advantage that it can be supplied uniformly.

次に、上述した検討結果を踏まえ、リン窒化除去と金属化の両立可否を確認する実験を行った。リン含有物質として、粒径を1~3mmに調整した鉄鉱石10gをアルミナ製ボート上に乗せて、小型の電気抵抗炉内に静置した。その炉内にArガスを1リットル/minで供給しながら所定温度(600~1400℃)まで加熱した後、Arガスの供給を停止し、そのArガスに代え一酸化炭素(CO)と窒素(N)との混合ガス3リットル/minを供給し、60分間一定温度に保持した。なお一酸化炭素と窒素の混合ガスの比率は、窒素分圧PN2が0~1atmの範囲となるように変化させた。所定の時間経過後、一酸化炭素と窒素の混合ガスの供給を停止してArガス1リットル/minに切り替え、室温まで降温させた後に前記鉄鉱石を回収した。この実験では、試薬カーボンを静置した側が上流となるようにガスを供給し、一酸化炭素ガスと試薬カーボンが先に反応するようにした。 Next, based on the above-mentioned results of the study, an experiment was conducted to confirm whether or not both phosphorus nitriding removal and metallization were possible. As a phosphorus-containing material, 10 g of iron ore with a particle size adjusted to 1 to 3 mm was placed on an alumina boat and placed in a small electric resistance furnace. After heating to a predetermined temperature (600 to 1400°C) while supplying Ar gas at 1 L/min into the furnace, the supply of Ar gas was stopped, and instead of the Ar gas, a mixed gas of carbon monoxide (CO) and nitrogen (N 2 ) was supplied at 3 L/min, and the temperature was maintained constant for 60 minutes. The ratio of the mixed gas of carbon monoxide and nitrogen was changed so that the nitrogen partial pressure P N2 was in the range of 0 to 1 atm. After a predetermined time had elapsed, the supply of the mixed gas of carbon monoxide and nitrogen was stopped and switched to Ar gas at 1 L/min, and the temperature was lowered to room temperature, and the iron ore was collected. In this experiment, the gas was supplied so that the side on which the reagent carbon was placed was the upstream side, so that the carbon monoxide gas reacted with the reagent carbon first.

図2は、前記処理を1000℃にて実施した還元処理前の鉄鉱石および還元処理後に得られた金属鉄の組成分析結果から求めたリン除去率ΔP(=[1-{(処理後金属鉄中P濃度)/(処理後金属鉄中T.Fe濃度)}/{(処理前鉄鉱石中P濃度)/(処理前鉄鉱石中T.Fe濃度)}]×100)(%)と窒素分圧PN2(atm)の関係を示すものである。この図2からわかるように、窒素分圧PN2が0および1atmの場合を除き、リン含有物質からはリンが除去されており、特に、0.2~0.9atmの範囲で55%以上という高いリン除去率が得られている。なお、窒素分圧PN2が0.2atm未満でリン除去率が低い理由としては、窒素分圧PN2が低すぎて所定の処理時間内では反応(a)によるリン除去が十分に進行しなかったためだと考えられる。また、窒素分圧PN2が0.9atm超えでは、COガスの供給量が少なく、鉄鉱石中の酸化鉄の熱分解により発生する酸素により、酸素分圧PO2が上昇し、リン窒化除去反応(a)が抑制されたためだと考えられる。このことは、100%窒素ガス(PN2=1atm)の供給では、リンが除去できていないことからも理解できる。 FIG. 2 shows the relationship between the phosphorus removal rate ΔP (=[1-{(P concentration in metallic iron after treatment)/(T.Fe concentration in metallic iron after treatment)}/{(P concentration in iron ore before treatment)/(T.Fe concentration in iron ore before treatment)}]×100) (%), which was determined from the composition analysis results of the iron ore before reduction treatment and the metallic iron obtained after the reduction treatment, in which the treatment was performed at 1000° C., and the nitrogen partial pressure P N2 (atm). As can be seen from FIG. 2, except for the cases in which the nitrogen partial pressure P N2 is 0 and 1 atm, phosphorus is removed from the phosphorus-containing substance, and in particular, a high phosphorus removal rate of 55% or more is obtained in the range of 0.2 to 0.9 atm. The reason why the phosphorus removal rate is low when the nitrogen partial pressure P N2 is less than 0.2 atm is considered to be that the nitrogen partial pressure P N2 is too low and therefore phosphorus removal by reaction (a) does not proceed sufficiently within the specified treatment time. In addition, when the nitrogen partial pressure P N2 exceeds 0.9 atm, the supply amount of CO gas is small, and oxygen generated by thermal decomposition of iron oxide in iron ore increases the oxygen partial pressure P O2 , suppressing the phosphorus nitriding removal reaction (a). This can be understood from the fact that phosphorus cannot be removed by supplying 100% nitrogen gas (P N2 = 1 atm).

図3は、前記処理を1000℃にて実施した際の処理後に得られた金属鉄の組成分析結果から求めた金属化率(Δη=(処理後金属鉄中M.Fe分析値)/(処理後金属鉄中T.Fe分析値))(%)と窒素分圧PN2(atm)の関係を示すものである。ここでT.Fe分析値は、処理後金属鉄中のT.Fe濃度をガラスビード法により定量した値である。M.Fe分析値は処理後金属鉄に対し、臭素メタノール溶液によって金属鉄のみを溶解した時の重量変化から定量した値である。この図3からわかるように窒素分圧PN2が1atmの場合を除き、70%以上という高い金属化率が得られている。これは窒素分圧PN2が0.9atm超えではCOガスの供給量が少なく、鉄鉱石中の酸化鉄の還元が進行しなかったためだと考えられる。このことは、100%窒素ガス(PN2=1atm)の供給では、金属化が生じていないことからも理解できる。 FIG. 3 shows the relationship between the metallization rate (Δη M = (analysis value of M.Fe in metallic iron after treatment)/(analysis value of T.Fe in metallic iron after treatment)) (%) obtained from the composition analysis of metallic iron obtained after the treatment at 1000° C. and the nitrogen partial pressure P N2 (atm). The T.Fe analysis value is the value obtained by quantifying the T.Fe concentration in metallic iron after treatment using the glass bead method. The M.Fe analysis value is the value obtained by quantifying the weight change when metallic iron after treatment is dissolved in a bromine-methanol solution. As can be seen from FIG. 3, a high metallization rate of 70% or more is obtained except when the nitrogen partial pressure P N2 is 1 atm. This is thought to be because when the nitrogen partial pressure P N2 exceeds 0.9 atm, the amount of CO gas supplied is small and the reduction of iron oxide in the iron ore does not proceed. This can be understood from the fact that no metallization occurs when 100% nitrogen gas (P N2 =1 atm) is supplied.

次に、図4は、前記処理をCO=10vol%(PCO=0.1atm)、N=90vol%(PN2=0.9atm)の混合ガスにて実施した実験前後の鉄鉱石の組成分析結果から求めたリン除去率ΔP(%)と処理温度T(℃)の関係を示す。この図4からわかるように、750~1300℃において、高いリン除去率ΔPが得られており、リンの窒化除去に好ましいことがわかる。なお、処理温度Tが750℃未満でリン除去率ΔPが低位な理由としては、724℃以下ではリン窒化除去に必要な酸素分圧PO2の低減を達成できなかったことが一因と考えられる。また、1350℃および1400℃においては、混合ガスへの切り替え時点で、鉄鉱石が半溶融~溶融しており、回収した試料が一体化しており、その結果、鉄鉱石粒の隙間や気孔が消失し、ガスと接触する界面積が大幅に減少したのが原因と考えられる。この点について、示差熱分析法により測定した鉄鉱石の融点(Tm)は1370℃であり、その0.95倍の1300℃では高いリン除去率が得られたため、「0.95×Tm(℃)」以下とすることがリン除去のための反応界面積確保の上で好ましいと考えられる。 Next, FIG. 4 shows the relationship between the phosphorus removal rate ΔP (%) and the treatment temperature T (° C.) obtained from the composition analysis results of the iron ore before and after the experiment in which the treatment was performed with a mixed gas of CO=10 vol% (P CO =0.1 atm) and N 2 =90 vol% (P N2 =0.9 atm). As can be seen from FIG. 4, a high phosphorus removal rate ΔP was obtained at 750 to 1300° C., which is preferable for removing phosphorus by nitriding. It is considered that one of the reasons why the phosphorus removal rate ΔP is low when the treatment temperature T is less than 750° C. is that the reduction of the oxygen partial pressure P O2 required for removing phosphorus by nitriding could not be achieved at 724° C. or less. In addition, at 1350° C. and 1400° C., the iron ore was semi-molten to molten at the time of switching to the mixed gas, and the collected sample was integrated, which is considered to be the cause of the disappearance of the gaps and pores of the iron ore particles and the significant reduction in the interface area in contact with the gas. In this regard, the melting point (Tm) of iron ore measured by differential thermal analysis is 1370°C, and a high phosphorus removal rate was obtained at 0.95 times that temperature, that is, 1300°C. Therefore, it is considered preferable to set the temperature at "0.95 × Tm (°C)" or less in order to ensure a reaction interface area for phosphorus removal.

図5は前記処理をCO=10vol%(PCO=0.1atm)、N=90vol%(PN2=0.9atm)の混合ガスにて実施した実験前後の鉄鉱石の組成分析結果から求めた金属化率と処理温度T(℃)の関係を示す。1300℃以下においてCOガスを供給したことにより高い金属化率が得られており、酸化鉄の還元に好ましいことが分かる。なお、1350℃および1400℃において金属化率が低位な理由は、上記のように混合ガスへの切り替え時点で鉄鉱石が半溶融~溶融した結果、ガスと接触する界面積が減少したためであると考えられる。 5 shows the relationship between the metallization rate and the treatment temperature T (°C) obtained from the composition analysis of iron ore before and after the experiment in which the treatment was carried out using a mixed gas of CO = 10 vol% ( PCO = 0.1 atm) and N2 = 90 vol% (PN2 = 0.9 atm). It is clear that a high metallization rate was obtained by supplying CO gas at 1300°C or less, which is preferable for the reduction of iron oxide. The reason why the metallization rate is low at 1350°C and 1400°C is thought to be that the iron ore becomes semi-molten to molten at the time of switching to the mixed gas as described above, resulting in a decrease in the interface area in contact with the gas.

なお、前記融点Tmは、固体試料が液体に変化する温度のことであり、下記第1~第3のいずれかの方法で決定することが簡易的であり望ましいが、これらの方法に限定するものではない。
・第1の方法は、るつぼ等の容器に固体試料を装入し、対象とするガス雰囲気下において、電気抵抗炉などにより毎分5℃、望ましくは毎分1℃以下で昇温しながら容器内の試料を連続的に観察し、固体試料の粒同士の隙間が消失し、表面に平滑面が生じた温度を融点とする方法である。
・第2の方法は、対象とするガス雰囲気下において、示差熱分析法により毎分5℃、望ましくは毎分1℃以下で昇温して測定した際の、吸熱ピークの極小点の温度を融点とする方法である。ここで、吸熱ピークが複数生じる場合、それぞれの吸熱ピークが生じた温度で測定を止めて、測定試料の外観を観察し、固体試料の粒同士の隙間が消失し、表面に平滑面が生じた温度の中で最も低温の吸熱ピークの極小点の温度を融点とする方法である。
・第3の方法は、電子計算機の熱力学計算ソフトを用い、試料組成を入力して温度を変化させて液相率を計算し、計算液相率が95%を超える温度を融点とする方法である。
The melting point Tm is the temperature at which a solid sample changes into a liquid, and is preferably determined by any one of the following first to third methods because it is easy to do so, but is not limited to these methods.
The first method is to place a solid sample in a container such as a crucible, and in the target gas atmosphere, use an electric resistance furnace or the like to raise the temperature at a rate of 5°C per minute, preferably 1°C per minute or less, while continuously observing the sample inside the container, and determine the melting point as the temperature at which the gaps between the grains of the solid sample disappear and a smooth surface appears on the surface.
The second method is to measure the temperature by differential thermal analysis in a target gas atmosphere at a rate of 5°C per minute, preferably 1°C per minute or less, and to determine the melting point as the temperature of the minimum point of the endothermic peak. When multiple endothermic peaks are observed, the measurement is stopped at the temperature at which each endothermic peak occurs, the appearance of the measured sample is observed, and the melting point is determined as the lowest temperature of the minimum point of the endothermic peak at which the gaps between the grains of the solid sample disappear and a smooth surface appears on the surface.
The third method is to use a thermodynamic calculation software on a computer, input the sample composition, change the temperature and calculate the liquid phase ratio, and define the temperature at which the calculated liquid phase ratio exceeds 95% as the melting point.

同様の手法をマンガン鉱石にも適用し、異なる粒径に対しても実験を試みたが、全ての条件において「0.2~0.9atm」の窒素分圧PN2の範囲、および「750℃以上、0.95×Tm(℃)以下」(ここで、Tmはマンガン鉱石の融点)の処理温度Tの範囲で高いリン除去率ΔPが得られることがわかった。 A similar method was also applied to manganese ore, and experiments were also conducted for different particle sizes. It was found that a high phosphorus removal rate ΔP could be obtained under all conditions within the range of nitrogen partial pressure P N2 of "0.2 to 0.9 atm" and the range of treatment temperature T of "750°C or higher and 0.95 × Tm (°C) or lower" (where Tm is the melting point of manganese ore).

以上説明したように、リン含有物質中のリンを窒化除去するためには、所定の温度での処理と窒素を含有する還元性ガスと窒素供給が必要と考えられる。このような処理をするための設備としては、電気炉、回転炉床炉、キルン炉、流動層型加熱炉、焼結機などの昇温と雰囲気制御とが可能な設備であればよい。 As explained above, in order to remove phosphorus from phosphorus-containing materials by nitriding, it is believed that treatment at a specified temperature and supply of a nitrogen-containing reducing gas and nitrogen are necessary. Equipment for such treatment can be any equipment capable of raising the temperature and controlling the atmosphere, such as an electric furnace, rotary hearth furnace, kiln furnace, fluidized bed heating furnace, or sintering machine.

(実施例1)
5トン/hr規模の回転炉床炉に鉄鉱石を装入し、加熱バーナーに供給する燃料と酸素の量とその比率を調整した。さらに炉内に供給する窒素、一酸化炭素、水素ガスの量を調整して、処理温度、酸素分圧および窒素分圧を制御した窒化処理を実施した。供給ガスと鉄鉱石が共存する領域において、供給ガスが鉄鉱石に初めて触れる位置である、供給ガスに対する上流の温度測定とガス組成分析とを行った。酸化還元反応は下記化学式4に示す反応(d)または下記化学式5に示す反応(e)によって代表され、酸素分圧はガス組成分析の測定値から下記(4)式および(5)式、または、(6)式および(7)式より算出した。(4)式および(6)式はそれぞれ反応(d)および(e)のギブズ自由エネルギーΔG°を表し、(5)式および(7)式はそれぞれ反応(d)および(e)の平衡定数Kを表す。(4)式ないし(7)式中、Tは測定した温度(K)、Rは気体定数(cal/(K・mol))、PCO、PCO2、PH2およびPH2Oはガス組成分析におけるCO、CO、HおよびHOの分圧である。処理条件および実施結果を表1~6に示す。
Example 1
Iron ore was charged into a rotary hearth furnace with a capacity of 5 ton/hr, and the amount and ratio of fuel and oxygen supplied to the heating burner were adjusted. The amounts of nitrogen, carbon monoxide, and hydrogen gas supplied to the furnace were adjusted to carry out a nitriding process in which the treatment temperature, oxygen partial pressure, and nitrogen partial pressure were controlled. In the region where the supply gas and iron ore coexist, the temperature measurement and gas composition analysis were performed upstream of the supply gas, which is the position where the supply gas first comes into contact with the iron ore. The oxidation-reduction reaction is represented by reaction (d) shown in chemical formula 4 below or reaction (e) shown in chemical formula 5 below, and the oxygen partial pressure was calculated from the measured value of the gas composition analysis using the following formulas (4) and (5), or (6) and (7). Formulas (4) and (6) represent the Gibbs free energy ΔG° of reactions (d) and (e), respectively, and formulas (5) and (7) represent the equilibrium constant K of reactions (d) and (e), respectively. In the formulas (4) to (7), T is the measured temperature (K), R is the gas constant (cal/(K·mol)), and P CO , P CO2 , P H2 and P H2O are the partial pressures of CO, CO 2 , H 2 and H 2 O in the gas composition analysis. The treatment conditions and results are shown in Tables 1 to 6.

Figure 0007476871000004
Figure 0007476871000004

Figure 0007476871000005
Figure 0007476871000005

Figure 0007476871000006
Figure 0007476871000006

Figure 0007476871000007
Figure 0007476871000007

Figure 0007476871000008
Figure 0007476871000008

Figure 0007476871000009
Figure 0007476871000009

Figure 0007476871000010
Figure 0007476871000010

Figure 0007476871000011
Figure 0007476871000011

Figure 0007476871000012
Figure 0007476871000012

Figure 0007476871000013
Figure 0007476871000013

表1の処理No.1~3から明らかなように、雰囲気中に窒素ガスおよび還元性ガスであるCOガスを含有する時にリンの除去および高い金属化率が得られた。雰囲気中に窒素ガスが含まれない、表1の処理No.4~6において、リンの除去は全く確認されなかった。雰囲気中に還元性ガスが含まれない、表1の処理No.7~9において、リンの除去および酸化鉄の金属への還元は全く確認されなかった。 As is clear from treatments No. 1 to 3 in Table 1, phosphorus removal and a high metallization rate were achieved when the atmosphere contained nitrogen gas and CO gas, a reducing gas. In treatments No. 4 to 6 in Table 1, where the atmosphere did not contain nitrogen gas, no phosphorus removal was observed. In treatments No. 7 to 9 in Table 1, where the atmosphere did not contain a reducing gas, no phosphorus removal or reduction of iron oxide to metal was observed.

表2の処理No.10~33から明らかなように、酸素分圧PO2が下記(1)式を満たす時に高い金属化率が得られていることがわかる。一方、(1)式の条件を外した場合に金属化率が低い原因としては、表2の処理No.34~45は、酸化鉄の還元に必要な酸素分圧PO2の低減を達成できなかったと考えられる。
[式1]
logPO2≦-1.45×10-5+0.0479T-48.2 (1)
As is clear from Process Nos. 10 to 33 in Table 2, a high metallization rate is obtained when the oxygen partial pressure P O2 satisfies the following formula (1). On the other hand, the reason for the low metallization rate when the condition of formula (1) is not met is believed to be that Process Nos. 34 to 45 in Table 2 were unable to achieve the reduction in the oxygen partial pressure P O2 required for the reduction of iron oxide.
[Formula 1]
logP O2 ≦−1.45×10 −5 T 2 +0.0479T−48.2 (1)

表3の処理No.46~51において、窒素分圧PN2が0.15atmにおいては、リン除去率は最大でも40%であった。つまり、窒素分圧PN2が0.15atmにおいては、雰囲気ガス中の窒素供給が不十分となり、リンの窒化反応(a)の進行が遅く、今回の処理時間の30minではリンが十分に除去されなかったためだと考えられる。 In the treatments No. 46 to 51 in Table 3, when the nitrogen partial pressure P N2 was 0.15 atm, the phosphorus removal rate was 40% at most. In other words, it is considered that when the nitrogen partial pressure P N2 was 0.15 atm, the supply of nitrogen in the atmospheric gas was insufficient, the progress of the nitriding reaction (a) of phosphorus was slow, and phosphorus was not sufficiently removed in the treatment time of 30 minutes.

また、表3の処理No.52~54において、窒素分圧PN2が0.95atmにおいては、リンの除去は全く確認されず、金属への還元も確認されなかった。その理由としては、雰囲気中のCOガス量が十分でなく、鉄鉱石の熱分解により生じる酸素、および鉄鉱石の装入口や装置の隙間からの巻き込み空気に含まれる酸素を除去しきれなかった結果、窒化除去や酸化鉄の還元に必要な酸素分圧PO2まで低減できなかったためと考えられる。このことは、ガス分析においてCOガスがほとんど検出されていないことと一致している。 In addition, in the cases of Processes No. 52 to 54 in Table 3, when the nitrogen partial pressure P N2 was 0.95 atm, no removal of phosphorus was observed, and no reduction to metal was observed. The reason for this is considered to be that the amount of CO gas in the atmosphere was insufficient, and oxygen generated by the thermal decomposition of iron ore and oxygen contained in the air entrained from the iron ore charging port and gaps in the equipment could not be completely removed, and as a result, the oxygen partial pressure P O2 could not be reduced to the level required for removing nitride and reducing iron oxide. This is consistent with the fact that almost no CO gas was detected in the gas analysis.

一方で、本発明方法に適合する表2に記載の処理No.10~33および表3に記載の処理No.46~51においてリン除去率は20%以上である。特に表2に記載の処理No.10~33においては、リン除去率が55%以上と高位となっている。このことから、高いリン除去率を得るためには、窒素分圧PN2(atm)が0.2atm以上0.9atm以下を満たすことが好ましい条件であることが分かる。 On the other hand, in Process Nos. 10 to 33 in Table 2 and Process Nos. 46 to 51 in Table 3, which are compatible with the method of the present invention, the phosphorus removal rate is 20% or more. In particular, in Process Nos. 10 to 33 in Table 2, the phosphorus removal rate is high, at 55% or more. This shows that in order to obtain a high phosphorus removal rate, a preferable condition is that the nitrogen partial pressure P N2 (atm) be 0.2 atm or more and 0.9 atm or less.

次に、図6は、処理温度T=1000℃における一酸化炭素分圧PCOと窒素分圧PN2の関係がリン除去および金属酸化物の還元に与える影響を図示したものである。図6には、表2の処理No.10~17および処理No.34~37、ならびに、表3の処理No.46、47および52をプロットした。ここで、リン除去率が55%以上かつ金属化率が60%以上の結果(表2の処理No.10~17)を○で、リン除去率が30%未満の結果(表3の処理No.46および47)を△で、金属化率が10%未満の結果(表2の処理No.34~37および表3の処理No.52)を×でプロットした。同様に、図7は、処理温度T=800℃における一酸化炭素分圧PCOと窒素分圧PN2の関係がリン除去および金属酸化物の還元に与える影響を図示したものである。図7には、表2の処理No.18~25および処理No.38~41、ならびに、表3の処理No.48、49および53を示す。ここで、リン除去率が55%以上かつ金属化率(Δη)(%)が60%以上の結果(表2の処理No.18~25)を○で、リン除去率が30%未満の結果(表3の処理No.48、49)を△で、金属化率が10%未満の結果(表2の処理No.38~41および表3の処理No.53)を×でプロットした。図8は、表2の処理No.26~33および処理No.42~45、ならびに、表3の処理No.50、51および54に示す1200℃における一酸化炭素分圧PCOと窒素分圧PN2の関係を図示したものである。ここで、リン除去率が55%以上かつ金属化率(Δη)(%)が60%以上の結果(表2の処理No.26~33)を○で、リン除去率が30%未満の結果(表3の処理No.50、51)を△で、金属化率が10%未満の結果(表2の処理No.42~45および表3の処理No.54)を×でプロットした。 Next, FIG. 6 illustrates the influence of the relationship between the carbon monoxide partial pressure P CO and the nitrogen partial pressure P N2 at a treatment temperature T=1000° C. on phosphorus removal and metal oxide reduction. In FIG. 6, Process Nos. 10-17 and 34-37 in Table 2, and Process Nos. 46, 47, and 52 in Table 3 are plotted. Here, results in which the phosphorus removal rate is 55% or more and the metallization rate is 60% or more (Process Nos. 10-17 in Table 2) are plotted with an ◯, results in which the phosphorus removal rate is less than 30% (Process Nos. 46 and 47 in Table 3) are plotted with a △, and results in which the metallization rate is less than 10% (Process Nos. 34-37 in Table 2 and Process No. 52 in Table 3) are plotted with an ×. Similarly, FIG. 7 illustrates the influence of the relationship between the carbon monoxide partial pressure P CO and the nitrogen partial pressure P N2 at a treatment temperature T=800° C. on phosphorus removal and metal oxide reduction. In FIG. 7, Process Nos. 10-17 and 34 in Table 2 are plotted with an ◯, results in which the phosphorus removal rate is less than 30% (Process Nos. 46 and 47 in Table 3) are plotted with an ×. FIG. 8 shows the results of Process Nos. 18 to 25 and 38 to 41 in Table 2, and Process Nos. 48, 49, and 53 in Table 3. Here, the results where the phosphorus removal rate was 55% or more and the metallization rate (Δη M ) (%) was 60% or more (Process Nos. 18 to 25 in Table 2) were plotted with an ◯, the results where the phosphorus removal rate was less than 30% (Process Nos. 48 and 49 in Table 3) were plotted with a △, and the results where the metallization rate was less than 10% (Process Nos. 38 to 41 in Table 2 and Process No. 53 in Table 3) were plotted with an ×. FIG. 8 shows the relationship between the carbon monoxide partial pressure P CO and the nitrogen partial pressure P N2 at 1200° C. shown in Process Nos. 26 to 33 and 42 to 45 in Table 2, and Process Nos. 50, 51, and 54 in Table 3. Here, the results where the phosphorus removal rate was 55% or more and the metallization rate (Δη M ) (%) was 60% or more (Process Nos. 26 to 33 in Table 2) were plotted with an ◯, the results where the phosphorus removal rate was less than 30% (Process Nos. 50 and 51 in Table 3) were plotted with a △, and the results where the metallization rate was less than 10% (Process Nos. 42 to 45 in Table 2 and Process No. 54 in Table 3) were plotted with an ×.

この図6~8から明らかなように、下記(2)式を満たす時に高い金属化率が得られていることがわかる。
[式2]
(-2.35×10-7+3.88×10-4T+0.587)(1-PN2)≦PCO (2)
As is clear from FIGS. 6 to 8, a high metallization rate is obtained when the following formula (2) is satisfied.
[Formula 2]
(-2.35 x 10-7T2 +3.88 x 10-4T +0.587) (1- P N2 ) ≤ P CO (2)

次に、図9は、表4に示す水素分圧PH2と窒素分圧PN2の関係を図示したものである。ここで、リン除去率が55%以上かつ金属化率が60%以上の結果(処理No.55~62)を○で、リン除去率が30%未満の結果(処理No.63、64)を△で、金属化率が10%未満の結果(処理No.65~69)を×でプロットした。図10は、表5に示す水素分圧PH2と窒素分圧PN2の関係を図示したものである。ここで、リン除去率が55%以上かつ金属化率が60%以上の結果(処理No.70~77)を○で、リン除去率が30%未満の結果(処理No.78、79)を△で、金属化率が10%未満の結果(処理No.80~84)を×でプロットした。図11は、表6に示す水素分圧PH2と窒素分圧PN2の関係を図示したものである。ここで、リン除去率が55%以上かつ金属化率が60%以上の結果(処理No.85~92)を○で、リン除去率が30%未満の結果(処理No.93、94)を△で、金属化率が10%未満の結果(処理No.95~99)を×でプロットした。 Next, FIG. 9 illustrates the relationship between the hydrogen partial pressure P H2 and the nitrogen partial pressure P N2 shown in Table 4. Here, the results where the phosphorus removal rate is 55% or more and the metallization rate is 60% or more (treatment Nos. 55 to 62) are plotted with an ◯, the results where the phosphorus removal rate is less than 30% (treatment Nos. 63 and 64) are plotted with a △, and the results where the metallization rate is less than 10% (treatment Nos. 65 to 69) are plotted with an ×. FIG. 10 illustrates the relationship between the hydrogen partial pressure P H2 and the nitrogen partial pressure P N2 shown in Table 5. Here, the results where the phosphorus removal rate is 55% or more and the metallization rate is 60% or more (treatment Nos. 70 to 77) are plotted with an ◯, the results where the phosphorus removal rate is less than 30% (treatment Nos. 78 and 79) are plotted with a △, and the results where the metallization rate is less than 10% (treatment Nos. 80 to 84) are plotted with an ×. FIG. 11 illustrates the relationship between the hydrogen partial pressure P H2 and the nitrogen partial pressure P N2 shown in Table 6. Here, the results where the phosphorus removal rate was 55% or more and the metallization rate was 60% or more (treatment Nos. 85 to 92) were plotted with an ◯, the results where the phosphorus removal rate was less than 30% (treatment Nos. 93 and 94) were plotted with a △, and the results where the metallization rate was less than 10% (treatment Nos. 95 to 99) were plotted with an ×.

この図9~11から明らかなように、下記(3)式を満たす時に高い金属化率が得られていることがわかる。
[式3]
(-1.31×10-8-8.85×10-4T+0.777)(1-PN2)≦PH2 (3)
As is clear from FIGS. 9 to 11, a high metallization rate is obtained when the following formula (3) is satisfied.
[Formula 3]
(-1.31 x 10-8T2-8.85 x 10-4T + 0.777) (1-P N2 ) ≦ P H2 (3)

上記(3)式の条件を外した場合にリン除去率あるいは金属化率が低い原因としては、以下の理由が考えられる。比較例は、酸化鉄の還元に必要な酸素分圧PO2の低減を達成できなかったと考えられる。 The reasons why the phosphorus removal rate or metallization rate is low when the condition of the above formula (3) is not met are considered to be as follows: It is considered that the Comparative Example was unable to achieve a reduction in the oxygen partial pressure P O2 required for the reduction of iron oxide.

なお、同様の設備を用い、処理時間を変更した場合にも、処理温度T、窒素分圧PN2および酸素分圧PO2が上記の条件を満たす時に、高いリン除去率が得られることが確かめられている。 It has been confirmed that even when similar equipment is used and the treatment time is changed, a high phosphorus removal rate can be obtained when the treatment temperature T, the nitrogen partial pressure P N2 and the oxygen partial pressure P O2 satisfy the above conditions.

本発明の金属の製造方法は、短時間かつ低コストで効果的にリン濃度の低い金属を製造することができるので、特に鉄鋼製錬・精錬に適用して、炭酸ガス排出量抑制に寄与し、産業上有用である。
The metal production method of the present invention can effectively produce metals with low phosphorus concentrations in a short time and at low cost, and is therefore industrially useful, particularly when applied to steel smelting and refining, and contributes to the reduction of carbon dioxide emissions.

Claims (7)

金属製錬用または金属精錬用の主原料もしくは副原料として用いられるリンを含有する金属酸化物を、処理温度、酸素分圧および窒素分圧の調整下で窒素を含有する還元性ガスと反応させ、前記金属酸化物中のリンを気体として除去しつつ前記金属酸化物を還元する還元処理を行なって金属を生成する、金属の製造方法。 A method for producing metals in which a phosphorus-containing metal oxide used as a main or auxiliary raw material for metal smelting or refining is reacted with a nitrogen-containing reducing gas while adjusting the processing temperature, oxygen partial pressure, and nitrogen partial pressure, and a reduction process is performed to reduce the metal oxide while removing the phosphorus in the metal oxide as a gas, thereby producing a metal. 前記金属酸化物の融点をTm(℃)として、前記処理温度T(℃)を750℃以上0.95×Tm(℃)以下の範囲とし、前記還元性ガスの前記酸素分圧PO2(atm)を下記(1)式の条件を満たす範囲とし、前記還元性ガスの前記窒素分圧PN2(atm)を0.2atm以上0.9atm以下の範囲として、前記還元処理を行なう、請求項1に記載の金属の製造方法。
[式1]
logPO2≦-1.45×10-5+0.0479T-48.2 (1)
The method for producing a metal as described in claim 1, wherein the reduction treatment is performed at a melting point of the metal oxide, Tm (°C), a treatment temperature T (°C) in the range of 750°C or higher and 0.95 x Tm (°C) or lower, the oxygen partial pressure P O2 (atm) of the reducing gas in the range satisfying the condition of the following formula (1), and the nitrogen partial pressure P N2 (atm) of the reducing gas in the range of 0.2 atm or higher and 0.9 atm or lower.
[Formula 1]
logP O2 ≦−1.45×10 −5 T 2 +0.0479T−48.2 (1)
前記還元性ガスの前記酸素分圧PO2(atm)をCO分圧PCO(atm)とCO分圧PCO2(atm)との比PCO/PCO2により調整する、請求項1または2に記載の金属の製造方法。 3. The method for producing a metal according to claim 1, wherein the oxygen partial pressure P O2 (atm) of the reducing gas is adjusted by a ratio P CO /P CO2 of a CO partial pressure P CO (atm) to a CO2 partial pressure P CO2 (atm). 前記還元性ガスは、COを含み、
CO分圧PCO(atm)は前記窒素分圧PN2(atm)との関係で下記(2)式の条件を満たす、請求項3に記載の金属の製造方法。
[式2]
(-2.35×10-7+3.88×10-4T+0.587)(1-PN2)≦PCO (2)
The reducing gas includes CO,
The method for producing a metal according to claim 3 , wherein the CO partial pressure P CO (atm) satisfies the condition of the following formula (2) in relation to the nitrogen partial pressure P N2 (atm).
[Formula 2]
(-2.35 x 10-7T2 +3.88 x 10-4T +0.587) (1- P N2 ) ≤ P CO (2)
前記還元性ガスの前記酸素分圧PO2(atm)をH分圧PH2(atm)とHO分圧PH2O(atm)との比PH2/PH2Oにより調整する、請求項1または2に記載の金属の製造方法。 3. The method for producing a metal according to claim 1, wherein the oxygen partial pressure P O2 (atm) of the reducing gas is adjusted by a ratio P H2 / P H2O of an H2 partial pressure P H2 (atm) to an H 2 O partial pressure P H2O (atm). 前記還元性ガスは、Hを含み、
分圧PH2(atm)は前記窒素分圧PN2(atm)との関係で下記(3)式の条件を満たす、請求項5に記載の金属の製造方法。
[式3]
(-1.31×10-8-8.85×10-4T+0.777)(1-PN2)≦PH2 (3)
The reducing gas comprises H2 ;
The method for producing a metal according to claim 5 , wherein the H 2 partial pressure P H2 (atm) satisfies the condition of the following formula (3) in relation to the nitrogen partial pressure P N2 (atm).
[Formula 3]
(-1.31 x 10-8T2-8.85 x 10-4T + 0.777) (1-P N2 ) ≦ P H2 (3)
前記金属酸化物が鉄鉱石またはマンガン鉱石である、請求項1ないし6のいずれか1項に記載の金属の製造方法。
The method for producing a metal according to any one of claims 1 to 6, wherein the metal oxide is iron ore or manganese ore.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010189762A (en) 2009-01-23 2010-09-02 Kobe Steel Ltd Process for manufacturing granular iron
CN104451016A (en) 2014-11-25 2015-03-25 北京神雾环境能源科技集团股份有限公司 Method for separating metal iron from phosphorus containing iron ore
WO2019131128A1 (en) 2017-12-26 2019-07-04 Jfeスチール株式会社 Method for removing phosphorus from phosphorus-containing substance
WO2020261767A1 (en) 2019-06-25 2020-12-30 Jfeスチール株式会社 Method for removing phosphorus from phosphorus-containing substance, method for producing starting material for metal smelting or starting material for metal refining, and method for producing metal

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010189762A (en) 2009-01-23 2010-09-02 Kobe Steel Ltd Process for manufacturing granular iron
CN104451016A (en) 2014-11-25 2015-03-25 北京神雾环境能源科技集团股份有限公司 Method for separating metal iron from phosphorus containing iron ore
WO2019131128A1 (en) 2017-12-26 2019-07-04 Jfeスチール株式会社 Method for removing phosphorus from phosphorus-containing substance
WO2020261767A1 (en) 2019-06-25 2020-12-30 Jfeスチール株式会社 Method for removing phosphorus from phosphorus-containing substance, method for producing starting material for metal smelting or starting material for metal refining, and method for producing metal

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