JP2010189670A - Method for producing phosphate resource raw material - Google Patents
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本発明は、製鋼工程において発生する製鋼スラグ中の燐を回収・濃化して、燐含有量の高い燐酸資源原料を製造する方法に関し、詳しくは、燐を含有する製鋼スラグに還元処理を実施した際に得られる、高濃度の燐を含有する溶銑に脱燐処理を施し、この脱燐処理で生成される脱燐スラグの燐含有量を、燐酸資源原料として活用可能なレベルに安定して高める方法に関するものである。 The present invention relates to a method for producing a phosphoric acid resource raw material having a high phosphorus content by recovering and concentrating phosphorus in steelmaking slag generated in a steelmaking process, and more specifically, reducing treatment was performed on steelmaking slag containing phosphorus. The hot metal containing a high concentration of phosphorus is dephosphorized, and the phosphorus content of the dephosphorized slag produced by this dephosphorization is stably increased to a level that can be used as a phosphoric acid resource raw material. It is about the method.
燐鉱石の枯渇問題や、中国、米国などによる燐鉱石の囲い込みのため、燐資源が高騰しており、鉄鋼プロセスにおいて発生する製鋼スラグ中の燐が貴重な燐資源として見直されている。しかしながら、高炉から出銑される溶銑中の燐濃度は０．１質量％程度であるため、従来の一般的な溶銑の予備脱燐処理や溶銑の脱炭精錬で生成される製鋼スラグ中の燐酸（Ｐ2Ｏ5）濃度は高々５質量％程度であり、燐酸資源としての活用先はほとんどない。そのため、これらの製鋼スラグは、路盤材などの土木用材料として使用され、スラグ中の燐は回収されていない。尚、予備脱燐処理とは、溶銑を転炉などにて脱炭精錬する前に、予め溶銑中の燐を除去する処理のことである。 Due to the problem of depletion of phosphate ore and the inclusion of phosphate ore by China, the United States, etc., phosphorus resources have soared, and phosphorus in steelmaking slag generated in the steel process has been reviewed as a valuable phosphorus resource. However, since the phosphorus concentration in the hot metal discharged from the blast furnace is about 0.1% by mass, phosphoric acid in the steelmaking slag produced by the conventional general hot metal preliminary dephosphorization treatment or hot metal decarburization refining. The concentration of (P 2 O 5 ) is at most about 5% by mass, and there are few applications for phosphoric acid resources. Therefore, these steelmaking slags are used as civil engineering materials such as roadbed materials, and phosphorus in the slag is not recovered. The preliminary dephosphorization treatment is a treatment for removing phosphorus in the hot metal in advance before decarburizing and refining the hot metal in a converter or the like.
また、近年、環境対策及び省資源の観点から、製鋼スラグのリサイクル使用を含めて、製鋼スラグの発生量を削減することが急務となっている。例えば、製鋼スラグを、造滓剤用の石灰源として鉄鉱石の焼結工程にリサイクルする試みもあるが、製鋼スラグ中の燐が高炉で還元されて、高炉から出銑される溶銑の燐濃度が増加するという問題がある。そこで、製鋼スラグから燐を除去する方法、或いは製鋼スラグから燐を回収する方法が提案されている。 In recent years, from the viewpoints of environmental measures and resource saving, it has become an urgent task to reduce the amount of steelmaking slag generated, including the recycling of steelmaking slag. For example, there is an attempt to recycle steelmaking slag to the iron ore sintering process as a lime source for ironmaking agents, but the phosphorus concentration in the hot metal discharged from the blast furnace is reduced by phosphorus in the steelmaking slag. There is a problem that increases. Then, the method of removing phosphorus from steelmaking slag, or the method of collect | recovering phosphorus from steelmaking slag is proposed.
例えば、特許文献１には、燐酸化物を含有する溶融または半溶融状態の製錬スラグに炭材を添加し、次いで減圧下において、酸素を上吹きし、炭材を燃焼させて製錬スラグを昇温し、炭材中の炭素により製錬スラグ中の燐酸化物を還元しながら、還元された燐を気化脱燐することにより、製錬スラグ中の燐を除去する技術が開示されている。 For example, in Patent Document 1, carbon material is added to molten or semi-molten smelted slag containing phosphorous oxide, oxygen is then blown up under reduced pressure, and the carbon material is burned to produce smelted slag. A technique for removing phosphorus in the smelting slag by evaporating and dephosphorizing the reduced phosphorus while raising the temperature and reducing the phosphorus oxide in the smelting slag with carbon in the carbonaceous material is disclosed.
また、特許文献２には、予備脱燐処理を行った後に生成された予備脱燐スラグを容器に装入し、炭材を添加して前記予備脱燐スラグ中の燐酸化物を還元して除去する脱燐スラグの再生処理方法において、前記容器には加熱手段を設け、該容器内の処理温度を１４５０℃以上、１７００℃未満に保持して、前記予備脱燐スラグに対する前記炭材の重量比を０．０２〜０．３とし、予備脱燐スラグ中の燐を溶銑側に回収し、予備脱燐スラグを再生する技術が開示されている。 In Patent Document 2, the preliminary dephosphorization slag generated after the preliminary dephosphorization treatment is charged into a container, and a carbon material is added to reduce and remove the phosphor oxide in the preliminary dephosphorization slag. In the dephosphorization slag regeneration treatment method, the container is provided with heating means, the treatment temperature in the container is maintained at 1450 ° C. or more and less than 1700 ° C., and the weight ratio of the carbonaceous material to the preliminary dephosphorization slag is Is set to 0.02 to 0.3, and phosphorus in the preliminary dephosphorization slag is recovered on the hot metal side to regenerate the preliminary dephosphorization slag.
また更に、特許文献３には、アルカリ金属炭酸塩を主成分とする造滓剤を用いた、溶銑または溶鋼の脱燐処理で生成する脱燐スラグを、水及び炭酸ガスで処理してアルカリ金属リン酸塩を含む抽出液を得て、該抽出液にカルシウム化合物を添加して、燐を燐酸カルシウムとして析出させて分離回収する技術が開示されている。 Furthermore, Patent Document 3 discloses that a dephosphorization slag produced by dephosphorization of hot metal or molten steel using a fouling agent mainly composed of an alkali metal carbonate is treated with water and carbon dioxide gas to produce an alkali metal. A technique is disclosed in which an extract containing a phosphate is obtained, a calcium compound is added to the extract, and phosphorus is precipitated as calcium phosphate to be separated and recovered.
しかしながら、上記従来技術には以下の問題点がある。 However, the above prior art has the following problems.
即ち、特許文献１では、減圧処理が必要であり、設備費が高く、また、製錬スラグは、燐が気化脱燐により除去されてリサイクル可能となるが、気化脱燐した燐は回収されておらず、燐資源の確保という観点からは効果的なリサイクル方法とはいえない。 That is, in Patent Document 1, a decompression process is required, the equipment cost is high, and the smelting slag is recyclable by removing phosphorus by vaporization dephosphorization, but the vaporized and dephosphorized phosphorus is recovered. In terms of securing phosphorus resources, it is not an effective recycling method.
特許文献２は、予備脱燐スラグ中の燐を溶銑側に回収する工程までは開示しているものの、その後、溶銑中に回収・濃化した燐をどのように処理するかについては言及していない。 Patent Document 2 discloses a process up to recovering phosphorus in the preliminary dephosphorization slag to the hot metal side, but mentions how to treat the recovered and concentrated phosphorus in the hot metal thereafter. Absent.
また、特許文献３は、湿式処理であり、湿式処理の場合、処理に必要な薬品が高価であるのみならず、大掛かりな処理設備が必要であり、設備費及び運転費ともに高価となる。 Further, Patent Document 3 is a wet process, and in the case of a wet process, not only chemicals necessary for the process are expensive, but also a large-scale processing facility is required, and both the equipment cost and the operation cost are expensive.
本発明は上記事情に鑑みてなされたもので、その目的とするところは、予備脱燐スラグや脱炭精錬スラグなどの燐を含有する製鋼スラグ中の燐を回収・濃化して、燐含有量の高い燐酸資源原料を安価に且つ効率的に製造する方法を提供することである。 The present invention has been made in view of the above circumstances, and its object is to recover and concentrate phosphorus in steelmaking slag containing phosphorus, such as preliminary dephosphorization slag and decarburized refining slag. It is to provide a method for efficiently and efficiently producing a high-phosphoric acid resource raw material.
上記課題を解決するための第１の発明に係る燐酸資源原料の製造方法は、製鋼精錬プロセスにおいて発生した燐を含有する製鋼スラグを、炭素、珪素、アルミニウムのうちの１種以上を含有する還元剤を用いて還元することにより、前記製鋼スラグ中の鉄酸化物及び燐酸化物が還元されて得られる、燐を０．５質量％以上含有する燐含有溶銑に対し、供給する酸素源の４０体積％以上の酸素源を酸素ガスとして上吹きランスを介して溶銑に吹き付けて供給するとともに、供給する石灰源の純ＣａＯ換算の４０質量％以上を前記上吹きランスを介して搬送用ガスとともに溶銑に吹き付けて供給し、前記石灰源の滓化促進剤としてフッ素源を使用することなく、酸素源及び石灰源を供給して脱燐処理を施し、生成される脱燐スラグ中の燐酸濃度を１０質量％以上に濃縮させ、該脱燐スラグを回収して燐酸資源原料とすることを特徴とするものである。 The manufacturing method of the phosphoric acid resource raw material which concerns on 1st invention for solving the said subject is the reduction | restoration containing 1 or more types of carbon, silicon, and aluminum for the steelmaking slag containing the phosphorus which generate | occur | produced in the steelmaking refining process. 40 volume of oxygen source to be supplied to phosphorus-containing hot metal containing 0.5 mass% or more of phosphorus obtained by reducing iron oxide and phosphorous oxide in the steelmaking slag by reducing with an agent % Of oxygen source is supplied as oxygen gas by spraying on the hot metal via the top blowing lance, and 40% by mass or more of pure lime source of the supplied lime source is supplied to the hot metal together with the carrier gas via the upper blowing lance. Without supplying a fluorine source as a hatching accelerator for the lime source, the oxygen source and the lime source are supplied to perform the dephosphorization treatment, and the phosphoric acid concentration in the dephosphorization slag to be generated is reduced. 0 wt% concentrated above, it is characterized in that the phosphate resource material to recover the dehydration phosphorus slag.
第２の発明に係る燐酸資源原料の製造方法は、第１の発明において、前記製鋼スラグ中の鉄酸化物及び燐酸化物が還元されて得られる、燐を０．５質量％以上含有する燐含有溶銑と、高炉から出銑される高炉溶銑とを、混合後の溶銑の燐濃度が０．５質量％以上２．０質量％以下となるように調整して混合し、その後、混合した溶銑に前記脱燐処理を施すことを特徴とするものである。 The method for producing a phosphoric acid resource raw material according to the second invention is the phosphorus-containing material containing 0.5% by mass or more of phosphorus obtained by reducing iron oxide and phosphorus oxide in the steelmaking slag in the first invention. The hot metal and the blast furnace hot metal discharged from the blast furnace are mixed so that the phosphorus concentration in the hot metal after mixing is 0.5 mass% or more and 2.0 mass% or less, and then mixed into the mixed hot metal. The dephosphorization treatment is performed.
本発明によれば、予備脱燐スラグや脱炭精錬スラグのような、製鋼精錬プロセスにおいて発生した燐を含有する製鋼スラグを還元して得られる、燐を０．５質量％以上含有する燐含有溶銑に対して、供給する酸素源の４０体積％以上の酸素源を酸素ガスとして上吹きランスを介して溶銑に吹き付けて供給するとともに、供給する石灰源の純ＣａＯ換算の４０質量％以上を前記上吹きランスを介して溶銑に吹き付けて供給して脱燐処理を施すので、脱燐反応が促進され、この脱燐処理により生成される脱燐スラグの燐酸濃度は１０質量％以上に濃縮されて、この脱燐スラグを燐酸資源原料として有効活用することが可能となる。また、脱燐スラグにはフッ素が含有されないので、水溶性の燐酸が確保され、燐酸肥料としても有効活用することができる。また更に、製鉄所の既設の設備で対処できるので、安価に且つ効率的に燐酸資源原料を製造することが実現される。 According to the present invention, phosphorus containing 0.5% by mass or more of phosphorus obtained by reducing steelmaking slag containing phosphorus generated in a steelmaking refining process, such as preliminary dephosphorization slag and decarburization refining slag. With respect to the hot metal, oxygen source of 40 volume% or more of the oxygen source to be supplied is supplied as oxygen gas by spraying the hot metal via the top blowing lance, and 40 mass% or more of the supplied lime source in terms of pure CaO is supplied. Since the dephosphorization treatment is performed by spraying and supplying the hot metal via the top blowing lance, the dephosphorization reaction is promoted, and the phosphoric acid concentration of the dephosphorization slag produced by this dephosphorization treatment is concentrated to 10% by mass or more. The dephosphorized slag can be effectively used as a phosphoric acid resource raw material. Moreover, since the dephosphorization slag does not contain fluorine, water-soluble phosphoric acid is ensured and can be effectively used as a phosphate fertilizer. Furthermore, since it can be dealt with by the existing facilities of the steelworks, it is possible to produce the phosphoric acid resource raw material at low cost and efficiently.
以下、本発明を詳細に説明する。 Hereinafter, the present invention will be described in detail.
本発明者らは、溶銑の予備脱燐処理時に発生する予備脱燐スラグや、通常溶銑或いは予備脱燐処理されていても予備脱燐処理後の燐濃度が製品の燐濃度レベルに比較して高い脱燐溶銑を使用した転炉脱炭精錬時に発生する脱炭精錬スラグ（「転炉スラグ」ともいう）などの燐を含有する製鋼スラグ（以下「燐含有製鋼スラグ」とも記す）から燐を回収する方法について研究・検討した。その結果、先ず、燐含有製鋼スラグを還元して高濃度の燐を含有する鉄または溶銑を生成させ、次いで、この鉄または溶銑から燐を分離回収する方法を見出した。以下に、研究・検討結果を説明する。 The present inventors have compared the preliminary dephosphorization slag generated during the preliminary dephosphorization treatment of the hot metal, and the phosphorus concentration after the preliminary dephosphorization treatment compared with the phosphorus concentration level of the product even though the hot metal or the preliminary dephosphorization treatment is performed. Phosphorus is removed from steel-containing slag (hereinafter also referred to as “phosphorus-containing steelmaking slag”), such as decarburization and refining slag (also referred to as “converter slag”) generated during converter decarburization and refining using high dephosphorization hot metal We studied and examined the method of recovery. As a result, first, a method for reducing iron-containing hot metal containing high-concentration phosphorus by reducing phosphorus-containing steelmaking slag and then separating and recovering phosphorus from this iron or hot metal was found. The following describes the results of research and examination.
燐含有製鋼スラグには、燐（Ｐ）はＰ2Ｏ5なる酸化物で含有されており、また、一般的に製鋼スラグはＣａＯ及びＳｉＯ2を主成分としており、燐は、カルシウム（Ｃａ）及び珪素（Ｓｉ）に比較して酸素との親和力が弱いことから、燐含有製鋼スラグを、炭素、珪素、アルミニウムなどで還元すれば、燐含有製鋼スラグ中のＰ2Ｏ5は容易に還元されることが分かった。この場合、燐含有製鋼スラグには、鉄が、ＦｅＯやＦｅ2Ｏ3の形態（以下、まとめて「ＦｅxＯ」と記す）の酸化物で含有されており、これらの鉄酸化物は酸素との親和力が燐と同等であるので、燐含有製鋼スラグを、炭素、珪素、アルミニウムなどで還元すると、同時に製鋼スラグ中のＦｅxＯが還元されることが分かった。これらの還元剤のなかでも、安価であることから特に炭素を用いることが経済的にも好ましい。 The phosphorus-containing steel slag contains phosphorus (P) as an oxide P 2 O 5 , and generally steel slag is mainly composed of CaO and SiO 2 , and phosphorus is calcium (Ca). In addition, since the affinity for oxygen is weaker than that of silicon (Si), P 2 O 5 in phosphorus-containing steelmaking slag is easily reduced if phosphorus-containing steelmaking slag is reduced with carbon, silicon, aluminum, or the like. I found out. In this case, the phosphorus-containing steelmaking slag, iron in the form of FeO and Fe 2 O 3 (hereinafter, collectively referred to as "Fe x O") are contained in the oxides, these iron oxide oxygen It has been found that when phosphorus-containing steelmaking slag is reduced with carbon, silicon, aluminum, etc., Fe x O in the steelmaking slag is reduced at the same time. Among these reducing agents, it is economically preferable to use carbon because it is inexpensive.
還元処理における還元剤の添加量は、燐含有製鋼スラグ中の鉄酸化物、燐酸化物、マンガン酸化物を還元するために必要な化学量論以上あれば十分であること、つまり、還元当量が１以上であれば十分であることが分かった。還元剤添加量の上限としては、還元当量が３を超えてもスラグの還元率に大きな変化が見られなかったことから、還元当量の上限を３とすることが経済的にも望ましい。 The amount of addition of the reducing agent in the reduction treatment is sufficient if it exceeds the stoichiometry necessary for reducing the iron oxide, phosphorus oxide, and manganese oxide in the phosphorus-containing steelmaking slag, that is, the reduction equivalent is 1 This proved to be sufficient. As the upper limit of the reducing agent addition amount, even if the reduction equivalent exceeds 3, the reduction rate of slag did not change greatly, so it is economically desirable to set the upper limit of the reduction equivalent to 3.
製鋼プロセスで発生する燐含有製鋼スラグとしては、溶銑の予備脱燐処理時に発生する予備脱燐スラグと、溶銑の転炉脱炭精錬時に発生する脱炭精錬スラグとが大半を占める。この予備脱燐スラグと脱炭精錬スラグとを、各々単独で還元処理してもよく、また、これらを混合したものを還元処理しても構わない。各製鉄所における予備脱燐スラグの発生量と脱炭精錬スラグの発生量とを考慮し、最適な混合比率を選択することもできる。 As the phosphorus-containing steelmaking slag generated in the steelmaking process, the preliminarily dephosphorized slag generated during the hot metal preliminary dephosphorization treatment and the decarburized refining slag generated during the hot metal converter decarburization refining account for the majority. The preliminary dephosphorization slag and the decarburized refining slag may be reduced individually, or a mixture of these may be reduced. The optimum mixing ratio can be selected in consideration of the amount of preliminary dephosphorization slag and the amount of decarburized refining slag at each steelworks.
また還元処理においては、その処理温度が比較的重要な因子であることも分かった。製鋼スラグ中の鉄酸化物及び燐酸化物は処理温度が１２００℃以上であれば、固体状態でも還元反応が進行することが分かった。但し、製鋼スラグ中の鉄酸化物及び燐酸化物を完全に還元して回収することを図る場合には、製鋼スラグを溶融状態にすることが好ましい。例えば、最も高融点である脱炭精錬スラグの単独還元処理においては、製鋼スラグを溶融状態にするには１６５０℃程度を必要とする。即ち、還元温度として、１２００℃以上１６５０℃以下の範囲とすれば、問題なく還元処理ができることが分かった。 In the reduction treatment, the treatment temperature was found to be a relatively important factor. It has been found that the reduction reaction proceeds even in a solid state when the processing temperature of iron oxide and phosphorous oxide in steelmaking slag is 1200 ° C. or higher. However, when it is intended to completely reduce and recover the iron oxide and phosphorous oxide in the steelmaking slag, it is preferable that the steelmaking slag is in a molten state. For example, in the single reduction treatment of decarburized refining slag having the highest melting point, about 1650 ° C. is required to bring the steelmaking slag into a molten state. That is, it was found that if the reduction temperature is in the range of 1200 ° C. or higher and 1650 ° C. or lower, the reduction treatment can be performed without any problem.
更なる実験により、還元により生成した鉄が溶融状態であれば、溶融鉄とスラグとは容易に分離し、また、この溶融鉄に、生成した燐が溶解することで、燐の製鋼スラグからの分離も迅速化することが分かった。これは、燐は鉄中への溶解度が高く、還元により生成した燐は、還元により生成した鉄に迅速に溶解するからである。 Further experiments show that if the iron produced by reduction is in a molten state, the molten iron and slag are easily separated, and the produced phosphorus dissolves in this molten iron, so that It was found that separation was also accelerated. This is because phosphorus has high solubility in iron, and phosphorus produced by reduction dissolves rapidly in iron produced by reduction.
製鋼スラグ及び還元により生成する鉄を溶融状態とする場合には、溶融スラグと溶融鉄とは２相に分離するので、例えば、掻き出し機などを用いて溶融スラグを処理容器から排出することで、両者を分離することができる。一方、製鋼スラグ及び生成する鉄が固体状態または半溶融状態のときには、還元後、生成した鉄を内部に有する製鋼スラグを破砕し、その後、磁力選別を施すことで両者を分離することができる。還元処理後の製鋼スラグは、燐含有量が低いので、例えば、石灰源として焼結工程などにリサイクルすることは、経済的にも環境的にも非常に好ましいことである。 When making the iron produced by the steelmaking slag and reduction into a molten state, the molten slag and the molten iron are separated into two phases.For example, by discharging the molten slag from the processing container using a scraper or the like, Both can be separated. On the other hand, when the steelmaking slag and the iron to be produced are in a solid state or a semi-molten state, after reduction, the steelmaking slag having the produced iron inside is crushed, and then the two can be separated by performing magnetic force sorting. Since the steelmaking slag after the reduction treatment has a low phosphorus content, for example, recycling to the sintering step as a lime source is very preferable both economically and environmentally.
製鋼スラグ及び還元により生成する鉄を溶融状態とする場合には、生成される溶融鉄の融点が低いほど、溶融鉄とスラグとの分離が促進されることから、生成される溶融鉄に炭素を溶解させ、溶融鉄として溶銑を生成させることが好ましいことも分かった。具体的には、炭素濃度が３質量％以上になると、溶銑の液相線温度が１３００℃以下となることから、溶銑の炭素濃度を３質量％以上確保することが好ましいことが分かった。生成される溶融鉄に炭素を溶解させるには、炭素を還元剤として使用する、または、珪素やアルミニウムなどを還元剤とする場合には、炭素を製鋼スラグと共存させることにより、生成する溶融鉄は浸炭して自ずと燐を高濃度で含有する溶銑となる。尚、この燐を高濃度で含有する溶銑を、高炉から出銑される高炉溶銑と区別するために、以下、「高燐溶銑」と呼ぶ。 When iron produced by steelmaking slag and reduction is in a molten state, the lower the melting point of the molten iron produced, the more the separation of molten iron and slag is promoted, so carbon is added to the produced molten iron. It has also been found that it is preferable to melt and produce hot metal as molten iron. Specifically, when the carbon concentration is 3% by mass or more, the liquidus temperature of the hot metal becomes 1300 ° C. or less. Therefore, it was found that it is preferable to secure the carbon concentration of the hot metal at 3% by mass or more. In order to dissolve carbon in the produced molten iron, carbon is used as a reducing agent, or when silicon or aluminum is used as a reducing agent, the molten iron produced by coexisting carbon with steelmaking slag. Is carburized to become hot metal containing phosphorus in a high concentration. The hot metal containing phosphorus at a high concentration is hereinafter referred to as “high phosphorus hot metal” in order to distinguish it from the blast furnace hot metal discharged from the blast furnace.
還元処理を行うための処理容器としては、上述した処理温度での還元処理に耐えうるものであればどのようなものでも構わない。具体的には、ロータリーキルン内に製鋼スラグと還元剤とを装入し、バーナーで燃焼加熱して還元処理を行う方法や、アーク溶解炉内に製鋼スラグと還元剤とを装入し、アーク加熱して還元処理を行う方法や、或いは、転炉や溶銑鍋などの処理容器内に製鋼スラグと還元剤とを装入し、酸素ガスで燃焼加熱しながら還元処理を行う方法などが挙げられる。 Any processing container may be used as long as it can withstand the reduction process at the above-described processing temperature. Specifically, steel slag and reducing agent are charged into a rotary kiln and burned and heated by a burner for reduction treatment, or steel melting slag and reducing agent are charged into an arc melting furnace for arc heating. Then, a method of performing the reduction treatment, or a method of charging the steelmaking slag and the reducing agent in a processing vessel such as a converter or a hot metal ladle, and performing the reduction treatment while being heated by combustion with oxygen gas, may be mentioned.
また、予め高炉溶銑をアーク溶解炉や処理容器に装入し、高炉溶銑を燐含有製鋼スラグと共存させた状態で還元処理を行うことも可能である。この場合には、温度が高く溶融状態の溶銑が予め存在するので、燐の製鋼スラグからの分離が促進される。但し、高炉溶銑の装入量が多くなると、高燐溶銑の燐濃度が低くなるので、高燐溶銑の燐濃度が０．５質量％以上を確保できる範囲で、高炉溶銑を装入する必要がある。高燐溶銑の燐濃度が０．５質量％未満の場合は、後述するように、高燐溶銑の脱燐処理で生成される脱燐スラグの燐酸濃度が安定して１０質量％を確保できなくなり、燐酸資源原料として利用できなくなる恐れがある。 It is also possible to charge the blast furnace hot metal into an arc melting furnace or a processing vessel in advance and perform the reduction treatment in a state where the blast furnace hot metal coexists with the phosphorus-containing steel slag. In this case, since the hot metal in a molten state exists in advance, the separation of phosphorus from the steelmaking slag is promoted. However, if the amount of the blast furnace hot metal is increased, the phosphorus concentration of the high phosphorus hot metal becomes lower. Therefore, it is necessary to charge the blast furnace hot metal within a range in which the phosphorus concentration of the high phosphorus hot metal can be secured to 0.5% by mass or more. is there. When the phosphorus concentration of the high phosphorus hot metal is less than 0.5% by mass, as will be described later, the phosphoric acid concentration of the dephosphorization slag produced by the dephosphorization treatment of the high phosphorus hot metal cannot be stably secured to 10% by mass. , There is a risk that it cannot be used as a phosphoric acid resource raw material.
次いで、還元処理により得られた高燐溶銑からの燐の分離・回収について説明する。 Next, the separation and recovery of phosphorus from the high phosphorus hot metal obtained by the reduction treatment will be described.
前述した予備脱燐スラグや脱炭精錬スラグを還元処理した結果、還元後の高燐溶銑には、燐が０．５〜７．５質量％程度含有されることが分かった。これは、燐含有製鋼スラグ中の燐及び鉄の質量比（Ｐ／Ｆｅ）が０．００５〜０．０７５であることに基づく。 As a result of reducing the above-mentioned preliminary dephosphorization slag and decarburization refining slag, it was found that about 0.5 to 7.5% by mass of phosphorus was contained in the high phosphorus hot metal after the reduction. This is based on the mass ratio (P / Fe) of phosphorus and iron in the phosphorus-containing steelmaking slag being 0.005 to 0.075.
本発明者らは、この高燐溶銑に対して脱燐処理を施すことで、この脱燐処理で生成される脱燐スラグに燐が濃化され、得られる脱燐スラグを燐酸資源原料として活用できると考えた。このとき、脱燐スラグにフッ素が存在すると、フッ素が燐酸（Ｐ2Ｏ5）及び石灰（ＣａＯ）と結合して安定的なアパタイトを形成し、燐酸の水溶性が阻害され、脱燐スラグを燐酸肥料用原料として利用したとき、燐酸の十分な水溶性が確保できないことから好ましくなく、従って、不可避的に混入されるフッ素以外には、フッ素源を使用せずに、脱燐処理する必要のあることが分かった。また、脱燐スラグを燐酸肥料として使用する場合には、燐酸肥料（脱燐スラグ）からフッ素が溶出し、土壌環境基準に対してフッ素溶出値が問題となる恐れがあり、この観点からも、本発明においてはフッ素源を使用しないこととした。 The present inventors perform dephosphorization treatment on this high phosphorus hot metal so that phosphorus is concentrated in the dephosphorization slag produced by this dephosphorization treatment, and the resulting dephosphorization slag is utilized as a phosphoric acid resource raw material. I thought it was possible. At this time, if fluorine exists in the dephosphorization slag, the fluorine combines with phosphoric acid (P 2 O 5 ) and lime (CaO) to form a stable apatite, the water solubility of phosphoric acid is inhibited, and the dephosphorization slag is reduced. When used as a raw material for phosphoric acid fertilizer, it is not preferable because sufficient water solubility of phosphoric acid cannot be ensured. Therefore, it is necessary to perform a dephosphorization treatment without using a fluorine source other than unavoidably mixed fluorine. I found out. In addition, when using dephosphorized slag as a phosphate fertilizer, fluorine is eluted from the phosphate fertilizer (dephosphorized slag), and the fluorine elution value may become a problem with respect to soil environmental standards. In the present invention, no fluorine source is used.
そこで、現在、高炉溶銑の予備脱燐処理に使用されている脱燐処理設備を用い、高燐溶銑に対して脱燐処理を施した。先ず、上吹きランスから吹き付け供給する酸素ガス（「気体酸素源」という）及びホッパーから上置き添加する鉄鉱石などの酸化鉄（「固体酸素源」という）を酸素源とし、ホッパーから上置き添加する塊状の生石灰を石灰源として脱燐処理を施した。尚、現在の高炉溶銑の予備脱燐処理は、酸素ガスまたは鉄鉱石などの酸化鉄を酸素源とし、この酸素源で溶銑中の燐を酸化して燐酸となし、この燐酸を生石灰などの石灰源により形成される溶融状態の精錬剤（スラグ）が吸収することで進行する。燐を吸収した脱燐処理後の精錬剤が脱燐スラグであり、石灰源の滓化（溶融化）を促進させるために、ＣａＦ2などのフッ素源を添加することもある。この場合、酸素源を脱燐剤、石灰源を脱燐精錬剤と称することもある。 Therefore, dephosphorization treatment was performed on the high phosphorus hot metal using the dephosphorization equipment currently used for the preliminary dephosphorization treatment of the blast furnace hot metal. First, oxygen gas supplied from the top blowing lance (referred to as “gas oxygen source”) and iron oxide such as iron ore added from the hopper (referred to as “solid oxygen source”) is used as the oxygen source and added from the hopper. The dephosphorization treatment was performed using the lump of quick lime to be used as a lime source. In addition, the current preliminary dephosphorization treatment of blast furnace hot metal uses oxygen gas or iron oxide such as iron ore as an oxygen source, and this oxygen source oxidizes phosphorus in the hot metal to form phosphoric acid, which is converted into lime such as quick lime. It progresses by absorbing the molten refining agent (slag) formed by the source. The refining agent after phosphorus removal treatment that has absorbed phosphorus is dephosphorization slag, and a fluorine source such as CaF 2 may be added to promote hatching (melting) of the lime source. In this case, the oxygen source may be referred to as a dephosphorizing agent, and the lime source may be referred to as a dephosphorizing agent.
しかしながら、上記の脱燐方法では、十分な脱燐反応は得られず、脱燐処理により生成される脱燐スラグの燐酸濃度は１０質量％未満であった。処理容器上から、生成される脱燐スラグの様子を観察すると、生成する脱燐スラグはほとんど固体状態であった。 However, in the above dephosphorization method, a sufficient dephosphorization reaction was not obtained, and the phosphoric acid concentration of the dephosphorization slag produced by the dephosphorization treatment was less than 10% by mass. When the state of the generated dephosphorization slag was observed from above the processing vessel, the generated dephosphorization slag was almost in a solid state.
これについて、本発明者らは以下のように考えた。つまり、高燐溶銑を脱燐処理する場合には、生成される脱燐スラグの組成は、ほぼトリカルシウムフォスフェート（３ＣａＯ・Ｐ2Ｏ5）となる。このトリカルシウムフォスフェートは、１２５０〜１４００℃の溶銑の温度範囲においては固体であるため、脱燐スラグがほぼ固相となり、溶銑表面を覆ってしまい、脱燐反応が促進されず、停滞したものと考えられた。 The present inventors considered this as follows. That is, in the case of dephosphorizing high phosphorus molten iron, the composition of the dephosphorized slag to be produced is almost tricalcium phosphate (3CaO · P 2 O 5 ). Since this tricalcium phosphate is solid in the hot metal temperature range of 1250 to 1400 ° C., the dephosphorization slag becomes almost a solid phase and covers the hot metal surface, and the dephosphorization reaction is not promoted and stagnated. It was considered.
この結果を踏まえ、石灰源の滓化を促進させるべく、上吹きランスから酸素ガスを吹き付けるとともに、上吹きランスから石灰源を搬送用ガスとともに吹き付けて供給する脱燐処理試験を行った。種々の試験から、供給する全酸素量のうちの４０体積％以上を上吹きランスからの酸素ガスとし、且つ、供給する石灰源のうちの純ＣａＯ換算の４０質量％以上を、上吹きランスから噴射される酸素ガス噴流の溶銑浴面での衝突位置（この位置を「火点」という）に、搬送用ガスともに上吹きランスから溶銑に吹き付けることで、脱燐反応が停滞することなく進行し、生成する脱燐スラグの燐酸濃度が１０質量％以上になることを確認した。また、得られた燐酸濃度が１０質量％以上の脱燐スラグは農業用燐酸肥料や化学工業用燐酸の資源原料として利用可能なことを確認した。 Based on this result, in order to promote the hatching of the lime source, an oxygen gas was blown from the top blowing lance, and a dephosphorization treatment test was conducted in which the lime source was blown together with the carrier gas from the top blowing lance. From various tests, 40% by volume or more of the total amount of oxygen to be supplied is oxygen gas from the top blowing lance, and 40% by weight or more of the supplied lime source in terms of pure CaO is from the top blowing lance. The dephosphorization reaction proceeds without stagnation by spraying the carrier gas to the molten iron from the upper blowing lance at the collision position (this position is called “fire point”) of the injected oxygen gas jet on the molten metal bath surface. It was confirmed that the phosphoric acid concentration of the resulting dephosphorized slag was 10% by mass or more. In addition, it was confirmed that the obtained dephosphorized slag having a phosphoric acid concentration of 10% by mass or more can be used as a raw material for agricultural phosphate fertilizer and phosphoric acid for chemical industry.
ここで、「供給する全酸素量のうちの４０体積％以上を上吹きランスからの酸素ガスとする」とは、「供給する酸素源のうちの固体酸素源は酸素ガスに換算して全酸素量の体積を求め、そのうちの４０体積％以上を上吹きランスから酸素ガスとして供給する」という意味である。また、「供給する石灰源のうちの純ＣａＯ換算の４０質量％以上」とは、石灰源には生石灰、石灰石、ドロマイトなど種々の種類があり、「供給する石灰源をＣａＯ純分に換算し、ＣａＯ純分の４０質量％以上の石灰源」という意味である。 Here, “40% by volume or more of the total amount of oxygen to be supplied is oxygen gas from the top blowing lance” means that “the solid oxygen source in the oxygen source to be supplied is converted into oxygen gas in total oxygen. The volume of the quantity is obtained, and 40% by volume or more of the volume is supplied as oxygen gas from the top blowing lance. Moreover, “40% by mass or more of pure lime source of lime source to be supplied” means that there are various types of lime sources such as quick lime, limestone and dolomite. , A lime source of 40% by mass or more of pure CaO ”.
上記のようにして脱燐処理することで、脱燐反応が停滞することなく進行する理由は、上吹きランスから供給される酸素ガス及び石灰源の比率が高く、上吹きランスから供給される酸素ガスにより形成される、所謂「火点」の領域近傍で脱燐反応を起こすことができ、固相の脱燐スラグが溶銑表面を覆い尽くす現象が軽減されるためと考えられる。石灰源の搬送用ガスとしては、窒素ガス、アルゴンガスなどの非酸化性ガス、及び、空気や酸素ガスなどの酸化性ガスの双方を使用することができるが、設備の保守が容易であることから、一般的には、非酸化性ガスが用いられる。 The reason why the dephosphorization reaction proceeds without stagnation by performing the dephosphorization process as described above is that the ratio of oxygen gas and lime source supplied from the top blowing lance is high, and oxygen supplied from the top blowing lance This is presumably because the dephosphorization reaction can occur in the vicinity of the so-called “fire point” region formed by the gas, and the phenomenon that the solid-phase dephosphorization slag completely covers the hot metal surface is reduced. As the transport gas for the lime source, both non-oxidizing gas such as nitrogen gas and argon gas and oxidizing gas such as air and oxygen gas can be used, but the maintenance of the equipment is easy. Therefore, in general, a non-oxidizing gas is used.
脱燐処理前の高燐溶銑の燐濃度が高すぎる場合、具体的には２．０質量％を超える場合には、上記の脱燐処理を実施しても脱燐処理後の溶銑中燐濃度は高炉溶銑に比較して依然として高く、このままの状態では、低燐鋼種用の鉄源としての適用は困難であり、高燐鋼種用に限定されてしまう。従って、高燐溶銑の燐濃度が２．０質量％を超える場合には、高燐溶銑に高炉溶銑を混合し、混合後の溶銑（「混合溶銑」と定義する）の燐濃度を０．５〜２．０質量％の範囲に調整することが好ましい。 When the phosphorus concentration of the high phosphorus hot metal before the dephosphorization treatment is too high, specifically when it exceeds 2.0% by mass, the phosphorus concentration in the hot metal after the dephosphorization treatment is carried out even if the above dephosphorization treatment is carried out. Is still higher than blast furnace hot metal, and in this state, it is difficult to apply as an iron source for a low phosphorus steel type, and it is limited to a high phosphorus steel type. Therefore, when the phosphorus concentration of the high phosphorus hot metal exceeds 2.0 mass%, the blast furnace hot metal is mixed with the high phosphorus hot metal, and the phosphorus concentration of the hot metal after mixing (defined as “mixed hot metal”) is 0.5. It is preferable to adjust to the range of -2.0 mass%.
脱燐処理前の高燐溶銑或いは混合溶銑の燐濃度が０．５〜２．０質量％の範囲である場合には、脱燐処理後の溶銑中燐濃度は高炉溶銑と同等またはそれ以下であることを本発明者らは確認している。尚、燐濃度が０．５質量％未満の溶銑を脱燐処理した場合は、生成する脱燐スラグの燐酸濃度は安定して１０質量％を確保できなくなるので、この観点からも高燐溶銑の燐濃度は０．５質量％を確保する必要がある。 When the phosphorus concentration in the high-phosphorus or mixed iron before dephosphorization is in the range of 0.5 to 2.0 mass%, the phosphorus concentration in the hot metal after dephosphorization is equal to or less than that in the blast furnace hot metal. The present inventors have confirmed that this is the case. In addition, when hot metal having a phosphorus concentration of less than 0.5% by mass is dephosphorized, the phosphoric acid concentration of the resulting dephosphorized slag cannot be ensured to be 10% by mass stably. It is necessary to secure a phosphorus concentration of 0.5% by mass.
本発明は、上記検討結果に基づいてなされたものであり、本発明は、製鋼精錬プロセスにおいて発生した燐を含有する製鋼スラグを、炭素、珪素、アルミニウムのうちの１種以上を含有する還元剤を用いて還元することにより、前記製鋼スラグ中の鉄酸化物及び燐酸化物が還元されて得られる、燐を０．５質量％以上含有する燐含有溶銑に対し、供給する酸素源の４０体積％以上の酸素源を酸素ガスとして上吹きランスを介して溶銑に吹き付けて供給するとともに、供給する石灰源の純ＣａＯ換算の４０質量％以上を前記上吹きランスを介して搬送用ガスとともに溶銑に吹き付けて供給し、前記石灰源の滓化促進剤としてフッ素源を使用することなく、酸素源及び石灰源を供給して脱燐処理を施し、生成される脱燐スラグ中の燐酸濃度を１０質量％以上に濃縮させ、該脱燐スラグを回収して燐酸資源原料とすることを特徴とする。 The present invention has been made based on the above examination results, and the present invention relates to a steelmaking slag containing phosphorus generated in a steelmaking refining process, and a reducing agent containing at least one of carbon, silicon, and aluminum. 40% by volume of the oxygen source to be supplied with respect to the phosphorus-containing molten iron containing 0.5% by mass or more of phosphorus obtained by reducing iron oxide and phosphorous oxide in the steelmaking slag. The above oxygen source is supplied as oxygen gas by spraying it on the hot metal via the top blowing lance, and 40 mass% or more of the supplied lime source in terms of pure CaO is sprayed on the hot metal together with the carrier gas via the above upper blowing lance. Without using a fluorine source as a hatching accelerator for the lime source, an oxygen source and a lime source are supplied to perform dephosphorization treatment, and the phosphoric acid concentration in the resulting dephosphorization slag is 10 Concentrated above amount%, characterized by a phosphate resource material to recover the dehydration phosphorus slag.
上記構成の本発明によれば、溶銑の予備脱燐スラグや溶銑の脱炭精錬スラグのような、製鋼精錬プロセスにおいて発生した燐を含有する製鋼スラグを還元して得られる、燐を０．５質量％以上含有する高燐溶銑に対して酸素源及び石灰源を添加して脱燐処理を施すので、この脱燐処理後に生成される脱燐スラグの燐酸濃度は１０質量％以上に濃縮されて、この脱燐スラグを燐酸資源原料として有効活用することが可能となる。 According to the present invention having the above-described configuration, the phosphorus obtained by reducing steelmaking slag containing phosphorus generated in the steelmaking refining process, such as hot metal preliminary dephosphorization slag and hot metal decarburization refining slag, Since the dephosphorization treatment is performed by adding the oxygen source and the lime source to the high phosphorus hot metal containing mass% or more, the phosphoric acid concentration of the dephosphorization slag produced after the dephosphorization process is concentrated to 10 mass% or more. The dephosphorized slag can be effectively used as a phosphoric acid resource raw material.
予備脱燐スラグと脱炭精錬スラグとを３相交流式のアーク溶解炉に装入し、更に還元剤としてコークスを装入し、アークを発生させて、予備脱燐スラグ、脱炭精錬スラグ及びコークスを加熱し、これら製鋼スラグの還元処理を実施した。この還元処理により得られた１５０トンの高燐溶銑を溶銑鍋に装入し、この高燐溶銑に処理条件を変えて種々の脱燐処理を実施した。また、比較のために、高炉溶銑に対しても同様の脱燐処理を実施した。 Preliminary dephosphorization slag and decarburization refining slag are charged into a three-phase alternating current arc melting furnace, coke is further charged as a reducing agent, an arc is generated, and preliminary dephosphorization slag, decarburization refining slag and Coke was heated and reduction treatment of these steelmaking slags was carried out. 150 tons of high phosphorus hot metal obtained by this reduction treatment was charged into a hot metal ladle, and various dephosphorization treatments were carried out by changing the processing conditions to this high phosphorus hot metal. For comparison, the same dephosphorization treatment was also performed on the blast furnace hot metal.
使用した脱燐処理設備は、上吹きランスを有しており、この上吹きランスから、酸素ガスを供給できるとともに、窒素ガスなどを搬送用ガスとして生石灰粉を酸素ガスによる火点位置に吹き付けることができる装置である。また、鉄鉱石や焼結鉱粉などの固体酸素源及び塊状の生石灰を上置き添加するための、ホッパー、シュートなどからなる供給装置も備えている。また更に、溶銑を攪拌するためのインジェクションランスも備えており、このインジェクションランスから必要に応じて攪拌用ガスとともに生石灰粉などを吹き込むことも可能な設備である。 The dephosphorization equipment used has an upper blowing lance, and oxygen gas can be supplied from this upper blowing lance, and quick lime powder is blown to the fire point position by oxygen gas using nitrogen gas or the like as a carrier gas. It is a device that can. In addition, a supply device including a hopper, a chute and the like for adding a solid oxygen source such as iron ore or sintered ore and lump quicklime is also provided. Furthermore, an injection lance for stirring the hot metal is also provided, and the lime powder and the like can be blown from the injection lance together with a stirring gas as required.
脱燐処理前の高燐溶銑の炭素濃度は、３．０〜５．０質量％であり、脱燐処理後の溶銑温度は１２５０〜１４００℃に調整した。酸素源の使用原単位は、酸素ガス換算でおよそ１５Ｎｍ3／ｔ−溶銑であり、生石灰の原単位はＣａＯ純分でおよそ３５ｋｇ／ｔ−溶銑であった。但し、高炉溶銑の脱燐処理（比較例１）では、生石灰の原単位はＣａＯ純分で１５ｋｇ／ｔ−溶銑とした。表１に脱燐処理条件及び処理結果を示す。 The carbon concentration of the high phosphorus hot metal before the dephosphorization treatment was 3.0 to 5.0% by mass, and the hot metal temperature after the dephosphorization treatment was adjusted to 1250 to 1400 ° C. The basic unit of oxygen source used was about 15 Nm 3 / t-hot metal in terms of oxygen gas, and the basic unit of quick lime was about 35 kg / t-hot metal in terms of pure CaO. However, in the dephosphorization treatment of the blast furnace hot metal (Comparative Example 1), the basic unit of quick lime was 15 kg / t-hot metal with a pure CaO content. Table 1 shows the dephosphorization treatment conditions and treatment results.
高炉溶銑を使用した比較例１では、脱燐処理条件は本発明の範囲内であるものの、溶銑の含有する燐の絶対値が少なく、脱燐スラグの燐酸（Ｐ2Ｏ5）の濃度は１０質量％未満となった。 In Comparative Example 1 using blast furnace hot metal, although the dephosphorization treatment conditions are within the scope of the present invention, the absolute value of phosphorus contained in the hot metal is small, and the concentration of phosphoric acid (P 2 O 5 ) in the dephosphorization slag is 10 It became less than mass%.
また、脱燐処理条件が本発明の範囲外である比較例２〜１６では、燐を０．５質量％以上含有する高燐溶銑を脱燐処理したにも拘らず、脱燐スラグの燐酸濃度は１０質量％未満となった。比較例２〜１６においては、脱燐スラグがほぼ固体状態であり、溶銑浴面を覆ってしまい、脱燐反応が停滞した。 Further, in Comparative Examples 2 to 16 where the dephosphorization treatment conditions are outside the scope of the present invention, the phosphoric acid concentration of the dephosphorization slag was obtained despite the dephosphorization treatment of the high phosphorus hot metal containing 0.5 mass% or more of phosphorus. Was less than 10% by mass. In Comparative Examples 2 to 16, the dephosphorization slag was almost in a solid state, covering the hot metal bath surface, and the dephosphorization reaction stagnated.
これに対して、脱燐処理条件が本発明の範囲内である本発明例１〜１５では、脱燐反応は停滞することなく進行し、脱燐スラグの燐酸濃度は何れも１０質量％以上であった。これは、比較例２〜１６と異なり、上吹きランスから供給される酸素ガス及び生石灰が多く、上吹きランスからの酸素ガス噴流によって形成される溶銑浴面の火点近傍で脱燐反応を起こすことができ、固体状態の脱燐スラグが溶銑浴面を覆ってしまう現象を軽減できたためである。 In contrast, in Invention Examples 1 to 15 where the dephosphorization conditions are within the scope of the present invention, the dephosphorization reaction proceeds without stagnation, and the phosphoric acid concentration of the dephosphorization slag is 10% by mass or more. there were. Unlike Comparative Examples 2-16, this has much oxygen gas and quicklime supplied from an upper blowing lance, and raise | generates a dephosphorization reaction in the hot spot vicinity of the hot metal bath surface formed by the oxygen gas jet from an upper blowing lance. This is because the phenomenon that the dephosphorization slag in the solid state covers the hot metal bath surface can be reduced.
本発明例１〜１５で得られた脱燐スラグは、燐酸肥料や化学工業用燐酸の資源原料として使用可能であった。 The dephosphorized slag obtained in Invention Examples 1 to 15 could be used as a raw material for phosphoric acid fertilizer and chemical industrial phosphoric acid.
予備脱燐スラグと脱炭精錬スラグとを混合した製鋼スラグを３相交流式のアーク溶解炉にてコークスにより還元処理して得られた高燐溶銑に高炉溶銑を混合し、混合後の混合溶銑の燐濃度を０．５〜２．０質量％の範囲に調整した。その後、この燐濃度を調整した混合溶銑に、脱燐処理条件を本発明の範囲内として、脱燐処理を実施した（本発明例１６〜２３）。 Blast furnace hot metal is mixed with high phosphorus hot metal obtained by reducing steelmaking slag, which is a mixture of preliminary dephosphorization slag and decarburized refining slag, with coke in a three-phase alternating current arc melting furnace, and mixed hot metal after mixing. The phosphorus concentration of was adjusted to a range of 0.5 to 2.0 mass%. Thereafter, the phosphorus mixture was adjusted and the dephosphorization treatment conditions were set within the scope of the present invention (Examples 16 to 23 of the present invention).
混合前の高炉溶銑の炭素濃度は４〜５質量％、高燐溶銑の炭素濃度は３．０〜５．０質量％であり、脱燐処理後の溶銑温度は１２５０〜１４００℃に調整した。酸素源の使用原単位は、酸素ガス換算でおよそ１５Ｎｍ3／ｔ−溶銑であり、生石灰の原単位はＣａＯ純分でおよそ３５ｋｇ／ｔ−溶銑であった。表２に脱燐処理条件及び処理結果を示す。 The carbon concentration of the blast furnace hot metal before mixing was 4-5% by mass, the carbon concentration of the high phosphorus hot metal was 3.0-5.0% by mass, and the hot metal temperature after dephosphorization was adjusted to 1250-1400 ° C. The basic unit of oxygen source used was about 15 Nm 3 / t-hot metal in terms of oxygen gas, and the basic unit of quick lime was about 35 kg / t-hot metal in terms of pure CaO. Table 2 shows the dephosphorization treatment conditions and treatment results.
表２に示すように、還元処理により得られた高燐溶銑と、高炉溶銑とを混合した混合溶銑の燐濃度を０．５〜２．０質量％に調整し、この混合溶銑に本発明の範囲の脱燐処理を施すことで、脱燐処理後の溶銑中燐濃度は高炉溶銑と同程度或いはそれ以下に低減することが分かった。脱燐処理後の混合溶銑の隣濃度が高炉溶銑と同等になれば、脱燐処理後の混合溶銑は、製鋼工程において何ら問題なく低燐鋼種用の鉄源として適用可能である。 As shown in Table 2, the phosphorus concentration of the mixed hot metal mixture obtained by mixing the high phosphorus hot metal obtained by the reduction treatment and the blast furnace hot metal was adjusted to 0.5 to 2.0% by mass. It was found that by performing a range of dephosphorization treatment, the phosphorus concentration in the hot metal after the dephosphorization treatment was reduced to the same level or lower than that in the blast furnace hot metal. If the adjacent concentration of the mixed hot metal after the dephosphorization treatment becomes equivalent to that of the blast furnace hot metal, the mixed hot metal after the dephosphorization treatment can be applied as an iron source for the low phosphorus steel type without any problem in the steelmaking process.
また、本発明例１６〜２３においても、脱燐処理後の脱燐スラグは１０質量％以上の燐酸（Ｐ2Ｏ5）を含有しており、燐酸資源原料として問題なく活用可能であった。 Further, in Examples 16 to 23 of the present invention, the dephosphorized slag after the dephosphorization treatment contained 10% by mass or more of phosphoric acid (P 2 O 5 ) and could be used without any problem as a phosphoric acid resource raw material.
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| JP2011208277A (en) * | 2010-03-12 | 2011-10-20 | Jfe Steel Corp | Method for recovering iron and phosphorus from steelmaking slag and raw material for phosphatic fertilizer |
| JP2017125244A (en) * | 2016-01-15 | 2017-07-20 | 新日鐵住金株式会社 | Production method of dephosphorization slag |
| JP2019151535A (en) * | 2018-03-06 | 2019-09-12 | 日本製鉄株式会社 | Method of producing phosphate slag fertilizer |
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| JP2008223095A (en) * | 2007-03-13 | 2008-09-25 | Jfe Steel Kk | Method for producing high phosphorus slag |
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| JP2002069526A (en) * | 2000-08-28 | 2002-03-08 | Nippon Steel Corp | Method for regeneration treating of dephosphorized slag |
| JP2006274442A (en) * | 2005-03-02 | 2006-10-12 | Jfe Steel Kk | Method for dephosphorize-treating molten iron |
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| JP2011208277A (en) * | 2010-03-12 | 2011-10-20 | Jfe Steel Corp | Method for recovering iron and phosphorus from steelmaking slag and raw material for phosphatic fertilizer |
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