JP5510361B2 - Method for producing sintered ore - Google Patents
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Description
本発明は、ＮＯｘの発生を抑制可能な焼結鉱の製造方法に関する。 The present invention relates to a method for producing sintered ore that can suppress generation of NOx.
焼結鉱の製造においては、燃料として使用する炭材の燃焼により、排ガス中に窒素酸化物（ＮＯｘ）が発生する。このＮＯｘの低減は、大気汚染の改善において重要な課題である。
ＮＯｘを低減する手段としては、例えば、特許文献１に、ＣａＯ含有量が５〜５０質量％であるＣａＯ−ＦｅｘＯ系複合酸化物を主成分とする触媒によるＮＯｘの除去技術が開示されている。
しかし、上記したＣａＯ−ＦｅｘＯ系複合酸化物は、石灰系原料と鉄鉱石を溶融成形して製造されるため、通常の焼結で副原料として使用される石灰系原料に比べて高価だった。
In the production of sintered ore, nitrogen oxides (NOx) are generated in the exhaust gas due to combustion of carbonaceous materials used as fuel. This reduction of NOx is an important issue in improving air pollution.
As a means for reducing NOx, for example,
However, since the CaO-FexO-based composite oxide described above is manufactured by melt-molding a lime-based material and iron ore, it is more expensive than a lime-based material used as an auxiliary material in normal sintering.
そこで、上記のような高価な酸化物を用いることなく、通常の焼結副原料として用いられる石灰系原料を使用し、この石灰系原料とコークスを混合し造粒してコークスの表面を石灰系原料で覆い、炭材燃焼時のＮＯｘを低減させることが検討されている。
ここで、石灰系原料とコークスを造粒する方法としては、例えば、特許文献２に記載の技術が開示されている。具体的には、粒径０．３ｍｍ以下の含有量が５０質量％以上のコークスに、生石灰と消石灰の１種又は２種（以下、単に石灰という）を配合し、その後、造粒し養生する方法である。なお、配合する石灰の平均粒度は０．５〜３ｍｍである。
Therefore, without using an expensive oxide as described above, a lime-based raw material used as a normal sintering auxiliary material is used, and the lime-based raw material and coke are mixed and granulated to form a lime-based surface of the coke. Covering with raw materials to reduce NOx during combustion of carbonaceous materials has been studied.
Here, as a method of granulating the lime-based raw material and coke, for example, a technique described in
しかしながら、特許文献２に記載の技術は、コークスの粒径が石灰の粒径よりも小さいことから、これを造粒すると、石灰の周囲にコークスが付着することになる。このため、コークスが低温領域で燃焼してしまい、ＮＯｘが多量に発生してＮＯｘの低減が図れない。
However, in the technique described in
本発明はかかる事情に鑑みてなされたもので、低温領域でのＮＯｘの発生を経済的に抑制可能な焼結鉱の製造方法を提供することを目的とする。 This invention is made | formed in view of this situation, and it aims at providing the manufacturing method of the sintered ore which can suppress generation | occurrence | production of NOx in a low-temperature area | region economically.
上記の課題を解決するためになされた本発明の要旨は、以下の通りである。
（１）炭材表面に消石灰を、該炭材に対する質量％で２質量％以上３０質量％以下の割合で被覆した表面被覆炭材を用いる焼結鉱の製造方法であって、
前記表面被覆炭材の製品水分量が１２．０質量％以上１５．５質量％以下となるように、前記炭材及び前記消石灰に水分を添加して造粒し、該消石灰の被覆層厚が５μｍ以上５００μｍ以下である前記表面被覆炭材を製造することを特徴とする焼結鉱の製造方法。
The gist of the present invention made to solve the above problems is as follows.
(1) A method for producing a sintered ore using a surface-covered carbon material in which slaked lime is coated on the carbon material surface at a ratio of 2% by mass to 30% by mass with respect to the carbon material,
The carbon material and the slaked lime are granulated by adding moisture so that the product moisture content of the surface-coated carbon material is 12.0% by mass or more and 15.5% by mass or less, and the coating layer thickness of the slaked lime is A method for producing a sintered ore, comprising producing the surface-coated carbon material having a size of 5 μm or more and 500 μm or less .
（２）前記炭材の粒度は、粒径０．２５ｍｍ未満の累積質量が２０質量％以下であり、粒径０．２５ｍｍ以上３ｍｍ以下の累積質量が４０質量％以上であることを特徴とする（１）記載の焼結鉱の製造方法。
( 2 ) As for the particle size of the carbonaceous material, the cumulative mass with a particle size of less than 0.25 mm is 20% by mass or less, and the cumulative mass with a particle size of 0.25 mm to 3 mm is 40% by mass or more. (1) Symbol placement method for producing sintered ore of.
本発明に係る焼結鉱の製造方法は、炭材の表面に消石灰を、炭材に対する質量％で２〜３０質量％の割合で被覆した表面被覆炭材を用いるので、消石灰を使用でき経済的である。
この表面被覆炭材を、その製品水分量が１２．０〜１５．５質量％となるように、炭材及び消石灰に水分を添加し造粒して製造するので、消石灰の被覆層厚が適正厚みとなった表面被覆炭材の歩留を向上できる。
従って、低温領域でのＮＯｘの発生を経済的に抑制可能である。
The method for producing a sintered ore according to the present invention uses a surface-covered carbon material in which the surface of the carbon material is coated with slaked lime at a ratio of 2 to 30% by mass with respect to the carbon material. It is.
Since this surface-coated carbon material is manufactured by adding moisture to the carbon material and slaked lime so that the product moisture content is 12.0 to 15.5% by mass, the coating layer thickness of slaked lime is appropriate. The yield of the surface-coated carbon material having a thickness can be improved.
Therefore, it is possible to economically suppress the generation of NOx in the low temperature region.
続いて、添付した図面を参照しつつ、本発明を具体化した実施の形態につき説明し、本発明の理解に供する。
まず、本発明の焼結鉱の製造方法に想到した経緯について説明する。
炭材が燃焼する際に生成（発生）するＮＯｘは、炭材中の窒素が酸化したものであり、図１に示されるように、１１５０℃以下（Ｏ２：２１％、Ａｒ：７９％）の低温で多量に生成することが確認されている。この図１の縦軸のＮＯｘ転換率は、式（１）により算出したものである。
｛ＮＯｘ転換率（ｍｏｌ％）｝
＝１００×｛ＮＯｘ発生量（ｍｏｌ）｝／｛燃料窒素入量（ｍｏｌ）｝ ・・・（１）
従って、ＮＯｘ生成を抑制するためには、炭材を極力、高温燃焼させることが重要である。
Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
First, the background of the sinter ore production method of the present invention will be described.
NOx generated (generated) when the carbonaceous material burns is obtained by oxidizing nitrogen in the carbonaceous material, and as shown in FIG. 1, 1150 ° C. or lower (O 2 : 21%, Ar: 79%) It has been confirmed that it is produced in large quantities at low temperatures. The NOx conversion rate on the vertical axis in FIG. 1 is calculated by the equation (1).
{NOx conversion rate (mol%)}
= 100 × {NOx generation amount (mol)} / {Fuel nitrogen input amount (mol)} (1)
Therefore, in order to suppress NOx production, it is important to burn the carbonaceous material as high as possible.
また、炭材中の微粉は、燃焼速度が速く低温で燃焼が完了するため、ＮＯｘを増大させると考えられる。即ち、炭材から、粒径が０．２５ｍｍ未満の微粉を除去できれば、ＮＯｘ発生量を低減できると考えられる。
しかし、炭材から、例え０．２５ｍｍ未満の微粉を除去したとしても、ＮＯｘ発生を抑制するためには、炭材の低温燃焼を避け、高温燃焼させる必要がある。
ここで、炭材を高温燃焼させるには、炭材表面を高温領域で溶融する被覆層で覆い、低温領域で周囲の大気中の酸素を遮断できればよい。これにより、ＮＯｘ発生を抑制することができる。
Further, the fine powder in the carbonaceous material is considered to increase NOx because the combustion speed is high and combustion is completed at a low temperature. That is, if fine powder having a particle size of less than 0.25 mm can be removed from the carbonaceous material, it is considered that the amount of NOx generated can be reduced.
However, even if fine particles of less than 0.25 mm are removed from the carbon material, in order to suppress the generation of NOx, it is necessary to avoid the low temperature combustion of the carbon material and to perform high temperature combustion.
Here, in order to burn the carbonaceous material at a high temperature, it is only necessary to cover the surface of the carbonaceous material with a coating layer that melts in a high-temperature region and to block oxygen in the surrounding atmosphere in a low-temperature region. Thereby, NOx generation can be suppressed.
前記した特許文献１には、ＣａＯ含有量が５〜５０質量％のＣａＯ−ＦｅｘＯ系複合酸化物を表面に被覆した炭材を用いて、ＣａＯ−ＦｅｘＯ系複合酸化物の触媒作用により、炭材の燃焼時に生成するＮＯｘを還元又は分解し除去することが開示されている。このＣａＯ含有量を５０質量％以下に制限したＣａＯ−ＦｅｘＯ系複合酸化物は融点が低く、１２００℃以上の高温域で溶融するため、これを炭材の表面に被覆することで、ある程度のＮＯｘ低減効果は期待される。
しかしながら、ＣａＯ−ＦｅｘＯ系複合酸化物は、石灰系原料と鉄鉱石を溶融成形して製造されるため、通常の焼結で副原料として使用される石灰系原料に比べて高価である。
In the above-mentioned
However, the CaO-FexO-based composite oxide is manufactured by melt-molding a lime-based raw material and iron ore, and is therefore more expensive than a lime-based raw material used as an auxiliary material in normal sintering.
そこで、本発明者らは、上記した高価な酸化物を用いることなく、通常の焼結副原料として用いられる消石灰を炭材表面の被覆物（被覆層ともいう）として用いることにより、炭材燃焼時のＮＯｘ低減を可能とした。
図２に示すように、本発明の一実施の形態に係る焼結鉱の製造方法は、炭材の表面に消石灰を、炭材に対する質量％で２質量％以上３０質量％以下（以下、単に２〜３０質量％ともいう）の割合で被覆した表面被覆炭材を用いる焼結鉱の製造方法であり、表面被覆炭材の製品水分量が１２．０質量％以上１５．５質量％以下（以下、単に１２．０〜１５．５質量％ともいう）となるように、炭材及び消石灰に水分を添加して造粒し、表面被覆炭材を製造する方法である。以下、詳しく説明する。
Therefore, the present inventors have used the slaked lime used as a normal sintering auxiliary material as a coating on the carbon material surface (also referred to as a coating layer) without using the above-described expensive oxide, thereby burning the carbon material. NOx reduction at the time was made possible.
As shown in FIG. 2, the manufacturing method of the sintered ore which concerns on one embodiment of this invention is 2 mass% or more and 30 mass% or less (henceforth, simply hereafter) by the mass% with respect to a carbon material. 2-30% by mass) and a method for producing sintered ore using a surface-coated carbon material coated at a ratio of 12.0% by mass to 15.5% by mass Hereinafter, it is a method of producing a surface-coated carbon material by adding moisture to the carbon material and slaked lime so as to be simply 12.0 to 15.5% by mass. This will be described in detail below.
まず、表面被覆炭材の製造に用いられる原料を除いた焼結鉱の配合原料を、ドラムミキサーやその他の混合機を用いて混合し、更に造粒機により造粒する。ここで、配合原料とは、焼結機に装入される原料のうち、床敷鉱を除いたものをいう。
また、表面被覆炭材は、粒径０．２５ｍｍ未満の微粉炭材を２０質量％以下にした粗粒炭材を用いることが好ましく、これを核粒子とし、これに消石灰を混合し、水分を添加して造粒することで製造する。ここで、粗粒炭材と消石灰を混合し造粒するには、例えば、ドラムミキサーやパンペレタイザー等の転動造粒機、その他の混合造粒機等を使用できる。
First, the blended raw material of sintered ore excluding the raw material used for the production of the surface-coated carbon material is mixed using a drum mixer or other mixer, and further granulated by a granulator. Here, the blended raw material refers to a raw material charged in the sintering machine, excluding the bedding ore.
Further, as the surface covering carbon material, it is preferable to use a coarse carbon material in which a fine carbonaceous material having a particle size of less than 0.25 mm is 20% by mass or less, which is used as a core particle, mixed with slaked lime, It is manufactured by adding and granulating. Here, in order to mix and granulate the coarse carbonaceous material and slaked lime, for example, a rolling granulator such as a drum mixer or a pan pelletizer, other mixed granulators, or the like can be used.
これにより、粗粒炭材を核粒子として、消石灰が被覆された表面被覆炭材が形成される。
そして、前記した造粒途中又は造粒後の配合原料に、上記した表面被覆炭材を添加し混合する。これは、配合原料を混合し造粒する前に、表面被覆炭材を添加することで、配合原料の混合時や造粒時に、炭材表面の被覆層が崩壊し剥離してしまうことを避けるためである。
As a result, a surface-coated carbon material coated with slaked lime is formed using the coarse carbon material as core particles.
And the above-mentioned surface covering carbonaceous material is added and mixed with the compounding raw material in the above-mentioned granulation middle or after granulation. This is to prevent the coating layer on the surface of the carbonaceous material from collapsing and peeling during mixing or granulation of the blended raw material by adding the surface coating carbonaceous material before mixing and granulating the blended raw material. Because.
ここで、炭材には、例えば、コークス（粉コークス）、無煙炭、その他の焼結鉱製造に用いられる燃料を使用できる。
また、消石灰は、一般に、粒径０．１５ｍｍ以下を７０質量％以上（１００質量％でもよい）含むものであり、その大部分（例えば、７０質量％以上、好ましくは８０質量％以上）が炭材よりも細かいものである。なお、消石灰には、水酸化カルシウムのみならず、例えば、石灰乳（消石灰の懸濁液）等も使用できる。この消石灰は、バインダーとなって、炭材表面に密着した被覆物を形成するため、例えば、配合原料との混合時や、焼結機への原料装入までの搬送過程において、炭材表面の被覆物の脱離を抑制できる。
Here, as the carbon material, for example, coke (powder coke), anthracite, and other fuels used for manufacturing sintered ore can be used.
In addition, slaked lime generally contains 70% by mass or more (or 100% by mass) of particles having a particle size of 0.15 mm or less, and the majority (for example, 70% by mass or more, preferably 80% by mass or more) is charcoal. It is finer than the material. For slaked lime, not only calcium hydroxide but also lime milk (slaked lime suspension) can be used. This slaked lime becomes a binder and forms a coating that adheres to the surface of the carbonaceous material.For example, during mixing with the blended raw material or in the conveying process until the raw material is charged into the sintering machine, Desorption of the coating can be suppressed.
また、炭材表面の消石灰は、炭材に対する質量％で２質量％以上３０質量％以下の割合で被覆する必要がある。
消石灰の炭材に対する質量％が２質量％未満の場合は、炭材表面全体を包囲する十分な被覆層の形成が難しくなり、炭材表面の一部が露出したり、また被覆層厚が薄くなり過ぎて、低温域での大気中の酸素の遮断によるＮＯｘ低減効果が得られなくなる。一方、炭材表面の消石灰量が３０質量％を超える場合、被覆層厚が厚くなり過ぎ、燃焼性が悪くなって焼結の生産性が損なわれる。
このため、炭材表面の消石灰を、炭材に対する質量％で２〜３０質量％としたが、下限を５質量％とすることが望ましく、また上限を１５質量％とすることが望ましい。
Moreover, it is necessary to coat | cover the slaked lime on the surface of a carbonaceous material in the ratio of 2 mass% or more and 30 mass% or less with respect to the carbonaceous material.
When the mass% of the slaked lime with respect to the carbon material is less than 2 mass%, it becomes difficult to form a sufficient coating layer surrounding the entire carbon material surface, and a part of the carbon material surface is exposed or the coating layer thickness is thin. Thus, the NOx reduction effect due to the blocking of oxygen in the atmosphere at low temperatures cannot be obtained. On the other hand, when the amount of slaked lime on the surface of the carbonaceous material exceeds 30% by mass, the coating layer thickness becomes too thick, the combustibility is deteriorated, and the productivity of sintering is impaired.
For this reason, although the slaked lime on the surface of the carbonaceous material is 2 to 30% by mass with respect to the carbonaceous material, the lower limit is preferably 5% by mass, and the upper limit is preferably 15% by mass.
前記したように、焼結工程のＮＯｘ発生量を低減するため、炭材に、粒径０．２５ｍｍ未満の微粉炭材の累積質量を２０質量％以下にした粗粒炭材を使用したが、更には１１．０質量％以下が望ましい。一方、粒径０．２５ｍｍ未満の炭材の下限値は、上記した理由から特に規定していないが、篩網による篩分け限界を考慮すれば５質量％である。
更に、粒径０．２５ｍｍ以上３ｍｍ以下の炭材の累積質量は、４０質量％以上であることが望ましく、７０質量％以上であることが特に望ましい。粒径が３ｍｍを超える炭材は、ＮＯｘの低減効果が３ｍｍの炭材とほとんど同じであるが、燃焼速度が遅く、焼結の生産性が損なわれる。一方、粒径０．２５ｍｍ以上３ｍｍ以下の炭材の累積質量の上限値は、上記した理由から特に規定していないが、１００質量％であることが好ましい。
As described above, in order to reduce the amount of NOx generated in the sintering process, a coarse carbon material in which the cumulative mass of fine carbonaceous material having a particle size of less than 0.25 mm was 20% by mass or less was used as the carbonaceous material. Furthermore, 11.0 mass% or less is desirable. On the other hand, the lower limit value of the carbonaceous material having a particle size of less than 0.25 mm is not particularly defined for the above-described reason, but is 5% by mass in consideration of the sieving limit by the sieve mesh.
Furthermore, the cumulative mass of the carbonaceous material having a particle size of 0.25 mm or more and 3 mm or less is desirably 40 mass% or more, and particularly desirably 70 mass% or more. Carbonaceous material having a particle size exceeding 3 mm has almost the same NOx reduction effect as that of 3 mm, but the combustion rate is slow and the productivity of sintering is impaired. On the other hand, the upper limit value of the cumulative mass of the carbonaceous material having a particle size of 0.25 mm or more and 3 mm or less is not particularly defined for the reason described above, but is preferably 100% by mass.
上記した表面被覆炭材の製造にあっては、表面被覆炭材の製品水分量が１２．０質量％以上１５．５質量％以下となるように、炭材及び消石灰に水分を添加して造粒する。
ここで、製品水分量とは、最終的な製品（焼結機へ装入される前の造粒物である表面被覆炭材）の水分量であり、消石灰及び炭材の含有水分量と混合及び造粒時の添加水分量との合計量で現される。なお、製品水分量は、乾燥状態の表面被覆炭材（消石灰及び炭材）１００に対する割合（質量％：外掛け）である。
In the production of the above surface-coated carbon material, water is added to the carbon material and slaked lime so that the product moisture content of the surface-coated carbon material is 12.0 mass% or more and 15.5 mass% or less. Grain.
Here, the product moisture content is the moisture content of the final product (surface-coated carbon material that is a granulated product before being charged into the sintering machine), and is mixed with the moisture content of slaked lime and carbonaceous material. And the total amount of water added during granulation. The product water content is a ratio (mass%: outer coating) to the surface-coated carbon material (slaked lime and carbon material) 100 in a dry state.
図２に示すように、表面被覆炭材の製品水分量を１２．０質量％以上１５．５質量％以下とした場合に、消石灰の被覆層厚が適正厚み、即ち５μｍ以上５００μｍ以下（以下、単に５〜５００μｍともいう）となった表面被覆炭材の歩留を向上できた（６０質量％以上）。
なお、表面被覆炭材は、消石灰とコークス（炭材）を、レディゲミキサー（混練機）に供給して混練した後、この混練物をパンペレタイザーに供給すると共に水分を添加して造粒し、コークス表面に消石灰を付着させて製造した。このレディゲミキサーは、内容積が８ｍ３であり、混練時の回転羽根の回転数を１００ｒｐｍ（回／分）とし、混練時間を３分とした。また、パンペレタイザーは、直径が５ｍであり、回転数を８ｒｐｍとし、傾斜角度を５７度とした。
As shown in FIG. 2, when the product moisture content of the surface-coated carbon material is 12.0 mass% or more and 15.5 mass% or less, the coating layer thickness of slaked lime is an appropriate thickness, that is, 5 μm or more and 500 μm or less (hereinafter, It was possible to improve the yield of the surface-coated carbon material (also simply referred to as 5 to 500 μm) (60% by mass or more).
The surface-covered carbonaceous material is granulated by supplying slaked lime and coke (carbonaceous material) to a readyge mixer (kneading machine) and kneading, and then supplying the kneaded material to a pan pelletizer and adding moisture. It was manufactured by attaching slaked lime to the coke surface. This Redige mixer had an internal volume of 8 m 3 , the rotational speed of the rotating blades during kneading was 100 rpm (times / min), and the kneading time was 3 minutes. The pan pelletizer had a diameter of 5 m, a rotational speed of 8 rpm, and an inclination angle of 57 degrees.
そして、歩留の測定は、以下の方法で行った。
まず、ＪＩＳ Ｋ２１５１のコークス類−試験方法に準じて、試料をサンプリングした。次に、このサンプリングした粒径別の試料を樹脂に埋込みカッティングし、顕微鏡にて、カッティングした面におけるコークス表面の付着消石灰の厚みを５０箇所測定した。そして、この５０箇所の測定値の平均値を計算して歩留りを求めた。
And the measurement of the yield was performed by the following method.
First, a sample was sampled according to JIS K2151 coke-test method. Next, the sample by particle size sampled was embedded in the resin and cut, and the thickness of the attached slaked lime on the coke surface on the cut surface was measured with a microscope at 50 locations. And the average value of these 50 measured values was calculated to determine the yield.
ここで、表面被覆炭材の製品水分量が１２．０質量％未満の場合、製品水分量が少な過ぎて炭材表面に消石灰が付着し難くなり、部分的に付着しない箇所が発生したり、また被覆層厚が薄くなり、消石灰の被覆層厚が５〜５００μｍとなった表面被覆炭材の歩留が低く（６０質量％未満）なる。このため、炭材表面の消石灰によるＮＯｘ抑制効果が減少する。
一方、水分量が１５．５質量％を超える場合、水分量が多過ぎて消石灰がだんご状（塊状）になり、被覆層厚の非常に厚い部分（５００μｍ超）や非常に薄い部分（５μｍ未満）が発生する。また、更に水分が多くなると、消石灰が炭材表面から過剰水分と共に流れ落ち易くなる。このため、消石灰の被覆層厚が５〜５００μｍとなった表面被覆炭材の歩留が低く（６０質量％未満）なり、炭材表面の消石灰によるＮＯｘ抑制効果が小さくなる。
Here, when the product moisture content of the surface-coated carbon material is less than 12.0% by mass, the product moisture content is too small to make it difficult for slaked lime to adhere to the carbon material surface, Further, the coating layer thickness is reduced, and the yield of the surface-coated carbonaceous material in which the coating layer thickness of slaked lime is 5 to 500 μm is low (less than 60% by mass). For this reason, the NOx suppression effect by the slaked lime on the carbonaceous material surface decreases.
On the other hand, if the amount of water exceeds 15.5% by mass, the amount of water is too much and the slaked lime becomes dumped (lumped), and the coating layer is very thick (over 500 μm) or very thin (less than 5 μm). ) Occurs. Further, when the moisture further increases, slaked lime tends to flow off from the carbon material surface together with excess moisture. For this reason, the yield of the surface covering carbonaceous material in which the coating layer thickness of the slaked lime becomes 5 to 500 μm is low (less than 60% by mass), and the NOx suppressing effect by the slaked lime on the carbonaceous material surface becomes small.
以上のことから、表面被覆炭材の製品水分量を１２．０〜１５．５質量％とし、炭材表面の消石灰の被覆層厚を５〜５００μｍとした表面被覆炭材の歩留を向上させる（６０質量％以上）。なお、更に、ＮＯｘ抑制効果を高めるには、製品水分量の下限値を１３．５質量％とし、また製品水分量の上限値を１５．０質量％として、消石灰の被覆層厚が５〜５００μｍとなる表面被覆炭材の歩留を高める（８５質量％以上）ことが好ましい。また、消石灰の被覆層厚の上限は、上記した理由から５００μｍとしたが、２５０μｍを超えるとＮＯｘ抑制効果の上昇傾向が緩やかになるため、炭材に対する消石灰量を調整して（減少させて）、２５０μｍとすることが好ましい。
以上の方法で製造した表面被覆炭材を、焼結機（図示しない）に装入して焼結鉱を製造する。
From the above, the product moisture content of the surface-coated carbon material is 12.0 to 15.5% by mass, and the yield of the surface-coated carbon material in which the coating layer thickness of the slaked lime on the carbon material surface is 5 to 500 μm is improved. (60 mass% or more). Furthermore, in order to further enhance the NOx suppression effect, the lower limit value of the product moisture content is set to 13.5 mass%, the upper limit value of the product moisture content is set to 15.0 mass%, and the coating layer thickness of slaked lime is 5 to 500 μm. It is preferable to increase the yield of the surface-coated carbon material (85% by mass or more). Moreover, although the upper limit of the coating layer thickness of slaked lime was set to 500 μm for the above-described reason, if it exceeds 250 μm, the increasing tendency of the NOx suppression effect becomes moderate. 250 μm is preferable.
The surface-coated carbon material produced by the above method is charged into a sintering machine (not shown) to produce a sintered ore.
焼結で生成するＮＯｘは、前記したように、炭材の１１５０℃以下の低温燃焼で急激に生成される。従って、ＮＯｘ生成を抑制するためには、炭材の低温燃焼を抑制し、極力高温燃焼させることが必要である。
上記した表面被覆炭材は、炭材の燃焼初期である低温領域で、炭材表面が被覆層で覆われているため、被覆層内の炭材の燃焼を抑えてＮＯｘの発生を抑制する。
一方、１２００℃以上の高温領域に到達すると、被覆層中の消石灰は、周囲の鉱石と反応し、カルシウムフェライトとなって溶融し、溶け落ちる。これにより、炭材表面は、消石灰が消失して裸の状態になるが、裸の状態であっても、表面被覆炭材は１２００℃以上の高温領域で燃焼されるため、ＮＯｘ発生は少なく、しかも活発な燃焼によって生産性を損うこともない。
従って、本発明の焼結鉱の製造方法を使用することで、低温領域でのＮＯｘの発生を経済的に抑制できる。
As described above, NOx generated by sintering is rapidly generated by low temperature combustion of the carbonaceous material at 1150 ° C. or lower. Therefore, in order to suppress the generation of NOx, it is necessary to suppress the low temperature combustion of the carbonaceous material and to perform the high temperature combustion as much as possible.
Since the above-described surface covering carbon material has a carbon material surface covered with a coating layer in a low temperature region at the initial stage of combustion of the carbon material, combustion of the carbon material in the coating layer is suppressed and generation of NOx is suppressed.
On the other hand, when it reaches a high temperature region of 1200 ° C. or higher, the slaked lime in the coating layer reacts with the surrounding ore, melts as calcium ferrite, and melts down. Thereby, the slaked lime disappears and the surface of the carbonaceous material becomes naked, but even in the naked state, the surface-covered carbonaceous material is burned in a high temperature region of 1200 ° C. or higher, so NOx generation is small, Moreover, productivity is not impaired by vigorous combustion.
Therefore, generation of NOx in a low temperature region can be economically suppressed by using the method for producing a sintered ore of the present invention.
次に、本発明の作用効果を確認するために行った実施例について説明する。
準備した焼結鉱の配合原料は、鉱石、副原料（石灰石、生石灰、及びＭｇＯ源）、返鉱、及び粉コークスである。なお、鉱石は８３．２質量％、石灰石は１２．８質量％、生石灰は１質量％、ＭｇＯ源は３質量％であり、この合計量（１００）に対して、返鉱を２０質量％、粉コークスを４．２質量％、それぞれ添加する構成にしている（外掛け）。
ここで、表面被覆炭材を製造にするに際し、上記した配合原料の粉コークス４．２質量％のうちの４質量％分を使用し、新たな消石灰を準備した。なお、消石灰を新たに添加するため、この消石灰のＣａ成分相当量分だけ、上記した石灰石量を減らした（０．６質量％）。
Next, examples carried out for confirming the effects of the present invention will be described.
The prepared raw materials of sintered ore are ore, auxiliary materials (limestone, quicklime, and MgO sources), return ore, and fine coke. The ore is 83.2% by mass, limestone is 12.8% by mass, quicklime is 1% by mass, and the MgO source is 3% by mass. It is set as the structure which adds 4.2 mass% of powder coke, respectively (outer hook).
Here, when producing the surface-coated carbonaceous material, a new slaked lime was prepared by using 4% by mass of 4.2% by mass of the powdered coke of the above-described blended raw material. In addition, in order to add slaked lime newly, the above-mentioned amount of limestone was reduced by an amount corresponding to the Ca component of this slaked lime (0.6% by mass).
まず、表面被覆炭材の製造条件を、以下に示す。
表面被覆炭材は、上記した消石灰と粉コークス（炭材）を、レディゲミキサー（混練機）に供給して混練した後、この混練物をパンペレタイザーに供給すると共に水分を添加して造粒し、粉コークス表面に消石灰を付着させて製造した。なお、レディゲミキサーは、内容積が８ｍ３であり、混練時の回転羽根の回転数を１００ｒｐｍ（回／分）とし、混練時間を３分とした。また、パンペレタイザーは、直径が５ｍであり、回転数を８ｒｐｍとし、傾斜角度を５７度とした。
ここで、使用した２種類の粉コークスの粒度分布を表１、表２に、消石灰の粒度分布を表３に、それぞれ示す。
First, the manufacturing conditions of the surface-coated carbon material are shown below.
The surface-coated carbon material is prepared by supplying the above-mentioned slaked lime and powdered coke (carbon material) to a Redige mixer (kneading machine) and kneading, then supplying this kneaded material to a pan pelletizer and adding water to granulate And slaked lime was attached to the surface of the powder coke. The Redige mixer had an internal volume of 8 m 3 , the rotational speed of the rotating blades during kneading was 100 rpm (times / min), and the kneading time was 3 minutes. The pan pelletizer had a diameter of 5 m, a rotational speed of 8 rpm, and an inclination angle of 57 degrees.
Here, the particle size distributions of the two types of powder coke used are shown in Tables 1 and 2, and the particle size distribution of slaked lime is shown in Table 3, respectively.
また、上記した表面被覆炭材を除いた焼結鉱の配合原料は、ドラムミキサーを用いて混合し、更に造粒機により４分間造粒した。なお、造粒時の添加水分は、上記した配合原料量の６．３質量％である。
そして、この造粒後の配合原料に、上記した表面被覆炭材を添加し混合して、鍋試験の試料に使用した。なお、鍋試験においては、上記した混合原料の層厚を５００ｍｍ、下方からの吸引風量を１．２Ｎｍ３／分、焼結温度を１３００℃とした。
この鍋試験に際し、ＮＯｘの測定は、（株）島津製作所の常圧式化学発光方式の測定器を用いて行った。
Moreover, the compounding raw material of the sintered ore except the above-mentioned surface covering carbon material was mixed using the drum mixer, and also granulated for 4 minutes with the granulator. In addition, the addition water | moisture content at the time of granulation is 6.3 mass% of an above-described mixing | blending raw material amount.
And the above-mentioned surface covering carbon material was added and mixed with the compounding raw material after this granulation, and it used for the sample of the pan test. In the pot test, the layer thickness of the mixed raw material was 500 mm, the suction air volume from below was 1.2 Nm 3 / min, and the sintering temperature was 1300 ° C.
During the pan test, NOx was measured using a normal pressure chemiluminescence measuring instrument manufactured by Shimadzu Corporation.
上記した試験条件と試験結果を、表４に示す。なお、表４中の粉コークスの粒度に記載のＮｏ．１は表１の粉コークスに、Ｎｏ．２は表２の粉コークスに、それぞれ該当し、表４中の消石灰の粒度に記載のＮｏ．３は表３の消石灰に該当する。また、表４中の消石灰の配合割合に記載した括弧「（ ）」内の数値は、粉コークス１００に対する割合（質量％）を表している。そして、表４中の水分の欄に記載した持込み水分量、添加水分量、及び製品水分量は、それぞれ乾燥状態の表面被覆炭材（消石灰及び炭材）１００に対する割合（質量％：外掛け）で示している（（製品水分量）＝（持込み水分量）＋（添加水分量））。
Table 4 shows the test conditions and test results described above. In addition, No. described in the particle size of the powder coke in Table 4 No. 1 corresponds to No. 1 in the powder coke of Table 1. No. 2 corresponds to the powder coke in Table 2, and No. 2 described in the particle size of slaked lime in Table 4 respectively. 3 corresponds to the slaked lime in Table 3. Moreover, the numerical value in the parenthesis “()” described in the blending ratio of slaked lime in Table 4 represents the ratio (mass%) with respect to the
表４に示す実施例１〜実施例５は、被覆させる消石灰量を、粉コークスに対し２〜３０質量％の範囲内とし、かつ表面被覆炭材の製品水分量を１２．０〜１５．５質量％の範囲内とした結果である。これにより、消石灰の被覆層厚が５〜５００μｍとなる表面被覆炭材の歩留りを６０質量％以上にすることができ、その結果、発生するＮＯｘ量を５濃度％以上低下させることができた。
ここで、実施例１〜実施例３のように、表面被覆炭材の製品水分量を、より好ましい１３．５〜１５．０質量％の範囲内とすることで、消石灰の被覆層厚が５〜５００μｍとなる表面被覆炭材の歩留りを９０質量％以上にすることができ、発生するＮＯｘ量を１０濃度％低下させることができた。
In Examples 1 to 5 shown in Table 4, the amount of slaked lime to be coated is in the range of 2 to 30% by mass with respect to the powdered coke, and the product moisture content of the surface-coated carbon material is 12.0 to 15.5. It is the result made into the range of the mass%. As a result, the yield of the surface-coated carbonaceous material having a slaked lime coating layer thickness of 5 to 500 μm can be increased to 60% by mass or more, and as a result, the amount of NOx generated can be reduced by 5% by concentration or more.
Here, like Example 1- Example 3, the coating layer thickness of slaked lime is 5 by making the product moisture content of a surface covering carbon material into the more preferable range of 13.5-15.0 mass%. The yield of the surface-coated carbonaceous material having a thickness of ˜500 μm could be 90% by mass or more, and the amount of NOx generated could be reduced by 10 concentration%.
一方、比較例１、２は、表面被覆炭材の製品水分量を、１２．０〜１５．５質量％の範囲外（比較例１：１１．０質量％、比較例２：１６．０質量％）とした結果であるが、水分量が不足し又は過剰となり、被覆層が適正厚みとなる表面被覆炭材の歩留が低く、炭材表面の消石灰によるＮＯｘ抑制効果がほとんど得られなかった。
また、比較例３は、被覆させる消石灰量を、粉コークスに対し２〜３０質量％の範囲外である２質量％未満（１．５質量％）とした結果であるが、消石灰量が少な過ぎて粉コークス表面全体を包囲する十分な被覆層の形成が難しくなった。その結果、粉コークス表面の一部が露出し、低温域での大気中の酸素の遮断によるＮＯｘ低減効果が得られなかった。
更に、比較例４は、被覆させる消石灰量を、粉コークスに対し２〜３０質量％の範囲外である３０質量％超（３５．０質量％）とした結果であるが、消石灰量が多過ぎて被覆層厚が厚くなり過ぎ、燃焼性が悪くなって焼結の生産性が損なわれた。
On the other hand, in Comparative Examples 1 and 2, the product moisture content of the surface-coated carbonaceous material is outside the range of 12.0 to 15.5% by mass (Comparative Example 1: 11.0% by mass, Comparative Example 2: 16.0% by mass). %), But the moisture content was insufficient or excessive, the yield of the surface-coated carbon material with the coating layer having an appropriate thickness was low, and the NOx suppression effect by slaked lime on the carbon material surface was hardly obtained. .
Moreover, although the comparative example 3 is a result which made the amount of slaked lime to coat | cover less than 2 mass% (1.5 mass%) which is outside the range of 2-30 mass% with respect to powder coke, there is too little amount of slaked lime. Therefore, it is difficult to form a sufficient coating layer surrounding the entire surface of the powder coke. As a result, part of the surface of the powder coke was exposed, and the NOx reduction effect due to the blocking of atmospheric oxygen in a low temperature range could not be obtained.
Furthermore, although the comparative example 4 is a result which made the amount of slaked lime to coat | cover exceed 30 mass% (35.0 mass%) which is outside the range of 2-30 mass% with respect to powder coke, there is too much amount of slaked lime. As a result, the coating layer thickness became too thick, the flammability deteriorated, and the productivity of sintering was impaired.
なお、実施例２は、消石灰量を粉コークスに対し２．５質量％まで低減させた結果であるが、表面被覆炭材の歩留りと発生するＮＯｘ量を、消石灰量を粉コークスに対し１５．０質量％とした実施例３と、同程度にすることができた。これは、実施例２が、表１に記載の粒度を備える粉コークスＮｏ．１、即ち粒径０．２５ｍｍ未満の累積質量が２０質量％以下であり、粒径０．２５ｍｍ以上３ｍｍ以下の累積質量が４０質量％以上の粉コークスを使用し、実施例３と比較して、微粉コークスの混入量を低減したことによる。
以上のことから、本発明の焼結鉱の製造方法を使用することで、低温領域でのＮＯｘの発生を経済的に抑制できることを確認できた。
In addition, although Example 2 is a result of having reduced the amount of slaked lime to 2.5 mass% with respect to the powder coke, the yield of the surface-coated carbon material and the amount of NOx generated are 15. It was possible to achieve the same level as in Example 3 where the content was 0% by mass. This is because powder coke No. 2 in Example 2 having the particle sizes shown in Table 1 was obtained. 1, that is, the cumulative mass with a particle size of less than 0.25 mm is 20% by mass or less, and the coke with a particle size of 0.25 mm or more and 3 mm or less is 40% by mass or more, and compared with Example 3. This is because the amount of fine coke mixed is reduced.
From the above, it has been confirmed that the use of the sintered ore production method of the present invention can economically suppress the generation of NOx in a low temperature region.
以上、本発明を、実施の形態を参照して説明してきたが、本発明は何ら上記した実施の形態に記載の構成に限定されるものではなく、特許請求の範囲に記載されている事項の範囲内で考えられるその他の実施の形態や変形例も含むものである。例えば、前記したそれぞれの実施の形態や変形例の一部又は全部を組合せて本発明の焼結鉱の製造方法を構成する場合も本発明の権利範囲に含まれる。 As described above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and the matters described in the scope of claims. Other embodiments and modifications conceivable within the scope are also included. For example, the case where the sintered ore production method of the present invention is configured by combining a part or all of the above-described embodiments and modifications is also included in the scope of the right of the present invention.
Claims (2)
前記表面被覆炭材の製品水分量が１２．０質量％以上１５．５質量％以下となるように、前記炭材及び前記消石灰に水分を添加して造粒し、該消石灰の被覆層厚が５μｍ以上５００μｍ以下である前記表面被覆炭材を製造することを特徴とする焼結鉱の製造方法。 A method for producing a sintered ore using a surface-coated carbon material in which slaked lime is coated on the carbon material surface at a ratio of 2% by mass to 30% by mass with respect to the carbon material,
The carbon material and the slaked lime are granulated by adding moisture so that the product moisture content of the surface-coated carbon material is 12.0% by mass or more and 15.5% by mass or less, and the coating layer thickness of the slaked lime is A method for producing a sintered ore, comprising producing the surface-coated carbon material having a size of 5 μm or more and 500 μm or less .
Priority Applications (1)
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| JP6880951B2 (en) * | 2016-09-21 | 2021-06-02 | 日本製鉄株式会社 | Manufacturing method of coal-containing agglomerate and coal-containing agglomerate |
| KR102177527B1 (en) * | 2018-08-02 | 2020-11-11 | 주식회사 포스코 | Method for pretreating binding material for sintering, apparatus for pretreating binding material for sintering and manufacturing method of sintered ore |
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| JPS51114302A (en) * | 1975-04-02 | 1976-10-08 | Nippon Steel Corp | Method of pre-processing sintered material for louering nox |
| JPS5384801A (en) * | 1976-12-30 | 1978-07-26 | Nippon Steel Corp | Operating method for sintering in which generation of nitrogen oxides is suppressed |
| JPS55107739A (en) * | 1979-02-14 | 1980-08-19 | Kawasaki Steel Corp | Sintering method with decrease of nitrogen oxide |
| JPS5893794A (en) * | 1981-12-01 | 1983-06-03 | Nippon Steel Corp | Preparation of powder coke for sintering iron ore |
| JPS6256533A (en) * | 1985-09-06 | 1987-03-12 | Nippon Kokan Kk <Nkk> | Method for pelletizing mixed material for sintering |
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