JP4430835B2 - Manufacturing method of artificial lightweight aggregate - Google Patents

Manufacturing method of artificial lightweight aggregate Download PDF

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JP4430835B2
JP4430835B2 JP2001062769A JP2001062769A JP4430835B2 JP 4430835 B2 JP4430835 B2 JP 4430835B2 JP 2001062769 A JP2001062769 A JP 2001062769A JP 2001062769 A JP2001062769 A JP 2001062769A JP 4430835 B2 JP4430835 B2 JP 4430835B2
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aggregate
rotary kiln
artificial lightweight
lightweight aggregate
limestone
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JP2002265243A (en
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正光 南部
泰雄 井澤
秀樹 和知
淳一 寺崎
崇幸 鈴木
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Taiheiyo Cement Corp
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2/00—Lime, magnesia or dolomite
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B18/02—Agglomerated materials, e.g. artificial aggregates
    • C04B18/027—Lightweight materials
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
    • C04B20/02—Treatment
    • C04B20/04—Heat treatment
    • C04B20/06—Expanding clay, perlite, vermiculite or like granular materials
    • C04B20/061—Expanding clay, perlite, vermiculite or like granular materials in rotary kilns
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
    • C04B20/02—Treatment
    • C04B20/04—Heat treatment
    • C04B20/06—Expanding clay, perlite, vermiculite or like granular materials
    • C04B20/068—Selection of ingredients added before or during the thermal treatment, e.g. expansion promoting agents or particle-coating materials

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Civil Engineering (AREA)
  • Processing Of Solid Wastes (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、人工軽量骨材の製造方法に関し、特に、焼成装置としてロータリーキルンを用い、融着防止材を添加して人工軽量骨材を製造する方法に関する。
【０００２】
【従来の技術】
従来、人工軽量骨材の製造にあたっては、例えば、特公昭６２−２４３７０号公報、特開平１１−２６３６４８号公報等に記載のように、ロータリーキルンを使用することが多い。また、骨材の軽量化は、ロータリーキルン内で使用原料が軟化する温度付近で発泡することによるものであって、この温度は「発泡温度」と呼ばれる。
【０００３】
ロータリーキルンに投入される骨材粒子は、２種類に大別できる。一つは、膨張頁岩のような岩石を粉砕し、発泡後の大きさを考慮した上で、適正粒度に整粒した粒子であり、造粒工程を必要としない。もう一つの骨材粒子は、原料を粉砕した後、各種方法で造粒したものであり、造粒した粒子は、「ペレット」と呼ばれる。
【０００４】
上記骨材粒子がロータリーキルンに投入され、回転が加えられると、粒子同士の摩擦や、ロータリーキルンのシェルとの摩擦等によって粒子の表面が削られ、粉体が発生する。以下、この粉体を「微粉」と呼ぶ。そして、微粉の発生量は、特に、ペレットで顕著であり、実際の焼成では、投入したペレットの５〜２０％が微粉となる。
【０００５】
人工軽量骨材をロータリーキルンで焼成するにあたって、上記微粉は、発泡温度領域に到達し、この付近で軟化する。そのため、微粉は骨材同士やロータリーキルンのシェル面との融着作用を起こし、場合によっては、直径２ｍ以上の塊状物が発生することがある。また、粒子がシェル面に付着することもあるので、シェル面に凹凸が発生する。微粉がほとんど発生しない条件でも、発泡温度に達すると骨材が軟化するので、骨材同士や骨材とキルンシェル面との融着が起こり、上記と同様の現象が発生する場合が多い。そして、塊状物が発生したり、シェル面に凹凸が発生すると、骨材粒子の焼成が不可能となるため、焼成を中断して塊状物や付着物を除去しなければならず、焼成の中断によって生産性が低下するという問題があった。
【０００６】
上記問題を解決して連続運転を可能とするため、従来、高融点の粉体をキルン内に吹き込んだり、流し込んだりして、上記骨材同士の融着や、骨材とキルンのシェル面との融着を防止することが行われていた。この融着防止材には、一般的には、純度の高いシリカやアルミナ等の高融点の粉体が使用され、カオリンやタルク等の粘土鉱物や、その他高融点の廃棄物が使用されることもあった。これらの融着防止材の骨材重量に対する添加率は、粗骨材の場合には１〜５％、細骨材の場合には３〜１０％程度であった。
【発明が解決しようとする課題】
【０００７】
上述のように、融着防止材を使用すると、使用した融着防止材の一部は骨材とともに製品側に排出され、他の融着防止材は燃焼気流とともに排気側で捕集される。また、上述のように、キルン内で原料骨材のペレットがすり減って微粉が発生するが、この微粉分も融着防止材とともに製品側や排気系に排出されていた。
【０００８】
ここで、製品側に排出される融着防止材中には、３〜１０％程度の原料骨材の微粉分が混入しているため、再度融着防止材として利用しようとしても融着防止材としての効果が小さいため、再利用は不可能である。また、この粉体は、高融点であるため、製品側に排出される融着防止材を人工軽量骨材の原料として混合利用すると、骨材の吸水率が増加したり、強度が低下するため、人工軽量骨材の原料としても使用することができず、従来は廃棄されていた。
【０００９】
一方、排気系に捕集される粉体中には、融着防止材が５〜２０％程度含有される。この融着防止材含有率は、微粉の発生量と、融着防止材の粒度及び添加率とに依存するが、融着防止材の粒度が小さくなるほど、また、使用率が高いほど燃焼気流により排気側に運ばれる融着防止材の量が増加する。従って、排気系に捕集される粉体中の融着防止材の含有率が低い場合には、人工軽量骨材の原料に混合して再利用できるが、融着防止材の含有率が高い場合には再利用できない場合もある。
【００１０】
尚、人工軽量骨材の焼成プロセスを改善することにより、原料ペレットのすり減りに伴う微粉の発生量を減少させることが可能である。この場合には、製品側に排出される融着防止材の再利用は可能となるものと推定される。しかし、微粉量を皆無にすることは経済的に不可能と考えられるので、排気側に捕集される融着防止材の再利用は困難であった。
【００１１】
上述のように、従来、融着防止材は、ほとんど再利用されずに廃棄されているため、人工軽量骨材の製造コストが上昇するとともに、廃棄処理のためのコストがかかるという問題があった。特に、融着防止材に、純度の高いシリカやアルミナ等を使用した場合には、人工軽量骨材の製造コストの増加が顕著であった。
【００１２】
そこで、本発明は、上記従来の人工軽量骨材の製造方法における問題点に鑑みてなされたものであって、安価で、かつ、再利用可能な融着防止材を用いることにより、製造コストを低減し、融着防止材を含む微粉の廃棄処理が不要な人工軽量骨材の製造方法を提供することを目的とする。
【００１３】
【課題を解決するための手段】
上記目的を達成するため、請求項１に記載の発明は、ロータリーキルンを用いて人工軽量骨材を製造する方法において、原料骨材の微粉による骨材同士または骨材とロータリーキルンのシェル面との融着を防止するための融着防止材に石灰石を使用することを特徴とする。
【００１４】
そして、請求項１に記載の発明によれば、融着防止材として従来よりも安価な石灰石を利用することにより、人工軽量骨材の製造コストを低減することができる。また、石灰石を使用して、製品としての骨材の表面に付着した生石灰を回収するとともに、ロータリーキルンの排ガス中に含まれる生石灰を回収したり、排ガス中に原料骨材の微粉を比較的多く含む場合には、回収した粉体を土壌固化材や土壌改良材として利用することにより、従来のように使用後の融着防止材を廃棄する必要がなく、環境に配慮した循環型社会の形成に資することができる。
【００１５】
請求項２に記載の発明は、前記石灰石の添加量を０．５乃至１０重量％としたことを特徴とする。石灰石の添加量が０．５％より少ないと融着を防止できない。また、後述するように、１０％以上添加しないと融着を起こす場合もあるが、人工軽量骨材の製造コストが上昇するため、添加量は１０％以下とするのが好適である。
【００１６】
１０％以上の石灰石の添加量を必要とするのは、以下の原因によるものである。すなわち、焼成温度が高すぎるとペレットが極端に軟化するので、１０％以上融着防止材の添加が必要となる。さらに、ペレットの造粒が不適切な場合には、ペレットの強度が低下し、多量（２０％以上）の微粉が発生する。このような場合にも１０重量％以上の添加が必要となる。しかし、このような異常な焼成温度や造粒の不適切なケースを考えなければ、１０％以下の添加量で十分対応することができる。
【００１７】
請求項３に記載の発明は、上記方法において、前記ロータリーキルンによって焼成された骨材の表面に付着した生石灰を除去する工程を含むことを特徴とする。これによって、除去した生石灰を有効利用することができる。尚、生石灰を除去するには、篩やエアーブロー等を利用することができる。
【００１８】
請求項４に記載の発明は、上記方法において、前記ロータリーキルンに投入される前記石灰石の粒径の好ましい一例として５ｍｍ以下としたことを特徴とする。
【００１９】
請求項５に記載の発明は、ロータリーキルンを用いて人工軽量骨材を製造する方法において、原料骨材の微粉による骨材同士または骨材とロータリーキルンのシェル面との融着を防止するため、融着防止材をロータリーキルン内に吹き込み、吹き込んだ融着防止材から生じた固体状物質を該ロータリーキルンの排気系、または該ロータリーキルンから排出される骨材の表面から回収して再利用することを特徴とする。
【００２０】
請求項５記載の発明によれば、吹き込んだ融着防止材から生じた固体状物質をを回収するため、従来のように使用後の融着防止材を含む物質を廃棄する必要がなく、環境に配慮した循環型社会の形成に資することができる。尚、このような融着防止材には、石灰石を選定することができる。
【００２１】
【発明の実施の形態】
次に、本発明の実施の形態について図面を参照しながら説明する。
本発明では、ロータリーキルンを用いて人工軽量骨材を製造するにあたって、原料骨材の微粉による骨材同士または骨材とロータリーキルンのシェル面との融着を防止するための融着防止材に石灰石を使用することを特徴としている。
【００２２】
この石灰石は、後述するように、十分な融着防止効果を奏するとともに、従来使用されていた純度の高いシリカやアルミナ等に比較して安価であることと、融着防止材として利用した後生石灰を回収することにより、従来不可避であった融着防止材の廃棄処理を不要とすることができるために選定したものである。
【００２３】
以下、石灰石を融着防止材として使用した人工軽量骨材の製造装置の好適例について図１を参照しながら説明する。
【００２４】
この人工軽量骨材製造装置１は、ペレット（原料骨材）供給部３と、バーナー４と、骨材排出部５とを備えたロータリーキルン（以下「キルン」と略称する）２を主要構成要素とするものであって、骨材排出部５側には、融着防止材としての石灰石をキルン２内に吹き込むための融着防止材供給設備６が備えられる。
【００２５】
また、骨材排出部５側には、骨材排出部５から排出された骨材Ａの表面に付着した生石灰を分離するため、篩７ａを備えた骨材・生石灰分離装置７（以下「分離装置」と略称する）と、分離装置７で分離された生石灰Ｑを集塵機９に導くためのダクト１０と、気流中の生石灰Ｑ２を捕捉するためのフィルタを備えた集塵機９が設けられる。
【００２６】
一方、ペレット供給部３側には、キルン２からの排ガスを集塵機１１に導くためのダクト１０と、ダクト１０から導入された排ガス中の生石灰Ｑ１を捕捉するためのフィルタを備えた集塵機１１が設けられる。尚、上記フィルタを有する集塵機９、１１の他に、サイクロン、電気集塵機等を使用することも可能である。
【００２７】
次に、上記構成を有する人工軽量骨材製造装置１の動作について説明する。
ペレット供給部３からキルン２内にペレットＰが供給され、バーナー４の火炎によって熱せられたキルン２内において、ペレットＰは、乾燥領域、焼結領域、発泡領域、冷却領域を経て骨材排出部５から製品として排出される。
【００２８】
ここで、キルン２の回転に伴って発生した上記骨材粒子の微粉は、発泡温度領域に到達し、この付近で軟化して、骨材同士やキルンのシェル面との融着作用を起こす。この融着を防止するため、融着防止材供給設備６を介して融着防止材としての石灰石Ｌが吹き込まれる。そして、融着が回避されて製品としての骨材Ａが骨材排出部５から排出される。尚、キルン２に吹き込まれる石灰石Ｌの粒径は、５ｍｍ程度以下であれば良く、輸送系統、供給・噴霧装置で目詰まり等のトラブルを起こすことのない粒度であれば問題はない。
【００２９】
キルン２内に吹き込まれた石灰石Ｌは、生石灰（ＣａＯ）と炭酸ガス（ＣＯ2）に分解され、生石灰Ｑ１の一部は、キルン２内の燃焼気流とともにダクト１０を介して集塵機１１に導入され、集塵機１１によって回収され、排ガスＧ１は大気へ開放される。
【００３０】
一方、使用した石灰石Ｌから発生した生石灰の一部は、骨材Ａの表面に付着して骨材排出部５から製品側に排出される。骨材Ａに付着した生石灰Ｑ２は、篩７ａによって篩われ、気流に乗ってダクト７を介して集塵機９に導入され、集塵機９によって回収される。排ガスＧ２は大気へ開放される。
【００３１】
集塵機９及び集塵機１１で回収された生石灰Ｑ１、Ｑ２は、製品として有効利用できることになる。また、排気系で集塵機１１によって捕集された粉体は、ペレットＰの微粉が含まれているが、土壌固化材や土壌改良材として利用できる。また、ＣａＯ含有量が４０％以上であれば、凝集剤や固化剤として使用することができる。尚、原料骨材を起源とする微粉の発生量を減少させることにより、排気系側についても高品質の生石灰を副産できることになる。
【００３２】
尚、上述のように、石灰石Ｌから発生した生石灰の一部が骨材Ａの表面に付着して製品側に排出されるため、製品骨材の表面には、０．０１〜０．０５％程度の生石灰が残存する。そのため、この骨材をアルカリ条件を嫌う用途には使用することができないが、コンクリート用骨材としては問題なく使用することができる。
【００３３】
また、石灰石を融着防止材として使用すると、キルン内において、石灰石が熱解離して炭酸ガスと生石灰が生成され、その際、エネルギーを消費する。例えば、１トンの原料骨材に対して３％の石灰石を使用した場合には、理論的に約１２６００ｋｃａｌのエネルギーを消費するが、系全体のエネルギー消費量から比較すると問題にならない程度のものである。
【００３４】
さらに、上記反応によって発生した炭酸ガスを大気に放出すると、地球温暖化の原因となり、環境には好ましくないともいえるが、長期的には、生石灰は炭酸化されて、解離した量と等しい量の炭酸ガスを吸収するため、問題にならない。
【００３５】
【発明の効果】
以上説明したように、本発明によれば、安価で、かつ、再利用可能な融着防止材を用いることにより、製造コストを低減し、融着防止材の廃棄処理が不要な人工軽量骨材の製造方法を提供することが可能となる。
【図面の簡単な説明】
【図１】本発明にかかる人工軽量骨材の製造方法を実施するための装置の好適例を示す概略図である。
【符号の説明】
１ 人工軽量骨材製造装置
２ キルン
３ ペレット供給部
４ バーナー
５ 骨材排出部
６ 融着防止材供給設備
７ 分離装置
７ａ 篩
８ ダクト
９ 集塵機
１０ ダクト
１１ 集塵機[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an artificial lightweight aggregate, and more particularly to a method for manufacturing an artificial lightweight aggregate by using a rotary kiln as a firing device and adding an anti-fusing material.
[0002]
[Prior art]
Conventionally, in manufacturing an artificial lightweight aggregate, a rotary kiln is often used as described in, for example, Japanese Patent Publication No. 62-24370, Japanese Patent Application Laid-Open No. 11-263648, and the like. Further, the weight reduction of the aggregate is due to foaming around the temperature at which the raw material used softens in the rotary kiln, and this temperature is called the “foaming temperature”.
[0003]
Aggregate particles put into the rotary kiln can be roughly divided into two types. One is a particle that is obtained by pulverizing a rock such as expanded shale and taking into consideration the size after foaming, and sizing it to an appropriate particle size, and does not require a granulation step. Another aggregate particle is obtained by pulverizing a raw material and then granulating it by various methods. The granulated particle is called a “pellet”.
[0004]
When the aggregate particles are put into a rotary kiln and rotated, the surface of the particles is scraped by friction between the particles, friction with the shell of the rotary kiln, etc., and powder is generated. Hereinafter, this powder is referred to as “fine powder”. And the generation amount of a fine powder is remarkable especially in a pellet, and 5-20% of the input pellet turns into a fine powder in actual baking.
[0005]
In firing the artificial lightweight aggregate with a rotary kiln, the fine powder reaches the foaming temperature region and softens in the vicinity thereof. Therefore, the fine powder causes a fusion action between the aggregates and the shell surface of the rotary kiln, and in some cases, a lump with a diameter of 2 m or more may be generated. Moreover, since particles may adhere to the shell surface, irregularities are generated on the shell surface. Even under conditions in which fine powder is hardly generated, the aggregate softens when the foaming temperature is reached. Therefore, the aggregates or the aggregate and the kiln shell surface are fused, and the same phenomenon as described above often occurs. If aggregates are generated or irregularities are generated on the shell surface, the aggregate particles cannot be fired. Therefore, the firing must be interrupted to remove the aggregates and deposits. As a result, there is a problem that productivity is lowered.
[0006]
In order to solve the above problems and enable continuous operation, conventionally, a high melting point powder is blown into the kiln or poured into the kiln, the aggregates are fused together, and the shell surface of the aggregate and the kiln It has been done to prevent fusion. In general, high-melting-point powders such as high-purity silica and alumina are used for this anti-fusing material, clay minerals such as kaolin and talc, and other high-melting-point waste are used. There was also. The addition ratio of these anti-fusing materials to the aggregate weight was about 1 to 5% in the case of coarse aggregate and about 3 to 10% in the case of fine aggregate.
[Problems to be solved by the invention]
[0007]
As described above, when the anti-fusing material is used, a part of the used anti-fusing material is discharged to the product side together with the aggregate, and the other anti-fusing material is collected on the exhaust side together with the combustion airflow. Moreover, as described above, the pellets of the raw material aggregate are worn out in the kiln and fine powder is generated. This fine powder is also discharged to the product side and the exhaust system together with the anti-fusing material.
[0008]
Here, since the anti-fusing material discharged to the product side contains about 3 to 10% of the raw material aggregate fine powder, the anti-fusing material is used even if it is used again as the anti-fusing material. Because of its small effect, it cannot be reused. In addition, since this powder has a high melting point, if the anti-fusing material discharged to the product side is used as a raw material for artificial lightweight aggregate, the water absorption rate of the aggregate increases or the strength decreases. It cannot be used as a raw material for artificial lightweight aggregates and has been discarded.
[0009]
On the other hand, the powder collected in the exhaust system contains about 5 to 20% of an anti-fusing material. This anti-fusing material content depends on the amount of fine powder generated and the particle size and addition rate of the anti-fusing material, but the smaller the particle size of the anti-fusing material and the higher the usage rate, the more The amount of anti-fusing material carried to the exhaust side increases. Therefore, when the content of the anti-fusing material in the powder collected in the exhaust system is low, it can be reused by mixing with the raw material of the artificial lightweight aggregate, but the content of the anti-adhesive material is high In some cases, it cannot be reused.
[0010]
In addition, it is possible to reduce the generation amount of the fine powder accompanying the abrasion of the raw material pellets by improving the firing process of the artificial lightweight aggregate. In this case, it is presumed that the anti-fusing material discharged to the product side can be reused. However, since it is considered economically impossible to eliminate the amount of fine powder, it is difficult to reuse the anti-fusing material collected on the exhaust side.
[0011]
As described above, conventionally, since the anti-fusing material is discarded without being reused, there is a problem that the manufacturing cost of the artificial lightweight aggregate is increased and the cost for the disposal is increased. . In particular, when high-purity silica, alumina, or the like is used as the anti-fusing material, an increase in the manufacturing cost of the artificial lightweight aggregate is remarkable.
[0012]
Therefore, the present invention has been made in view of the problems in the above-described conventional method for manufacturing an artificial lightweight aggregate, and the manufacturing cost can be reduced by using an inexpensive and reusable anti-fusing material. An object of the present invention is to provide a method for producing an artificial lightweight aggregate that is reduced and does not require disposal of fine powder containing an anti-fusing material.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is a method for producing an artificial lightweight aggregate using a rotary kiln, and is a method of melting aggregates of aggregates of raw material aggregates or between the aggregate and the shell surface of the rotary kiln. Limestone is used as an anti-fusing material for preventing adhesion.
[0014]
And according to invention of Claim 1, the manufacturing cost of an artificial lightweight aggregate can be reduced by utilizing a limestone cheaper than before as a fusion preventing material. In addition, limestone is used to recover quick lime adhering to the surface of aggregate as a product, and quick lime contained in rotary kiln exhaust gas is recovered, and the exhaust gas contains a relatively large amount of raw material aggregate fine powder. In some cases, the collected powder can be used as a soil-solidifying material or soil-improving material, eliminating the need to dispose of the anti-fusing material after use as in the past, and creating an environmentally friendly recycling society. Can contribute.
[0015]
The invention according to claim 2 is characterized in that the amount of limestone added is 0.5 to 10% by weight. If the amount of limestone added is less than 0.5%, fusion cannot be prevented. Further, as will be described later, fusion may occur if not added in an amount of 10% or more, but the amount added is preferably 10% or less because the manufacturing cost of the artificial lightweight aggregate increases.
[0016]
The reason why an amount of limestone added of 10% or more is required is as follows. That is, if the firing temperature is too high, the pellets are extremely softened, so that it is necessary to add an anti-fusing material of 10% or more. Furthermore, when the pellet granulation is inappropriate, the strength of the pellet is reduced and a large amount (20% or more) of fine powder is generated. In such a case, addition of 10% by weight or more is necessary. However, if such an abnormal firing temperature and an inappropriate case of granulation are not considered, an addition amount of 10% or less can sufficiently cope with it.
[0017]
The invention described in claim 3 is characterized in that, in the above method, the method includes the step of removing quick lime adhering to the surface of the aggregate fired by the rotary kiln. Thereby, the removed quicklime can be used effectively. In addition, in order to remove quick lime, a sieve, an air blow, etc. can be utilized.
[0018]
The invention described in claim 4 is characterized in that, in the above method, as a preferred example of the particle size of the limestone charged into the rotary kiln, it is 5 mm or less.
[0019]
The invention according to claim 5 is a method for manufacturing an artificial lightweight aggregate using a rotary kiln, in order to prevent fusion between aggregates due to fine powder of raw material aggregate or between the aggregate and the shell surface of the rotary kiln. An anti-adhesion material is blown into a rotary kiln, and a solid substance generated from the blown anti-fusion material is recovered from the exhaust system of the rotary kiln or the surface of aggregate discharged from the rotary kiln and reused. To do.
[0020]
According to the invention described in claim 5, in order to recover the solid substance generated from the blown anti-fusing material, it is not necessary to discard the substance containing the anti-fusing material after use as in the prior art. Can contribute to the formation of a recycling-oriented society. Note that limestone can be selected as such an anti-fusing material.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
In the present invention, when manufacturing an artificial lightweight aggregate using a rotary kiln, limestone is used as an anti-fusing material for preventing fusion between aggregates of raw material aggregates or between the aggregate and the shell surface of the rotary kiln. It is characterized by use.
[0022]
As will be described later, this limestone has a sufficient anti-fusing effect, and is inexpensive compared to conventionally used high-purity silica, alumina, and the like, and post-lime used as an anti-fusing material. This is selected because the disposal of the anti-fusing material, which has been unavoidable in the past, can be made unnecessary by collecting the material.
[0023]
Hereinafter, a preferred example of an artificial lightweight aggregate manufacturing apparatus using limestone as an anti-fusing material will be described with reference to FIG.
[0024]
The artificial lightweight aggregate manufacturing apparatus 1 includes a rotary kiln (hereinafter abbreviated as “kiln”) 2 including a pellet (raw material aggregate) supply unit 3, a burner 4, and an aggregate discharge unit 5 as main components. Therefore, an anti-fusing material supply facility 6 for blowing limestone as an anti-fusing material into the kiln 2 is provided on the aggregate discharging unit 5 side.
[0025]
Moreover, in order to separate the quicklime adhering to the surface of the aggregate A discharged from the aggregate discharge section 5 on the aggregate discharge section 5 side, an aggregate / quick lime separation device 7 (hereinafter referred to as “separation” having a sieve 7a is separated. And a dust collector 9 provided with a duct 10 for guiding the quicklime Q separated by the separation device 7 to the dust collector 9 and a filter for capturing the quicklime Q2 in the airflow.
[0026]
On the other hand, on the pellet supply unit 3 side, a dust collector 11 having a duct 10 for guiding the exhaust gas from the kiln 2 to the dust collector 11 and a filter for capturing quicklime Q1 in the exhaust gas introduced from the duct 10 is provided. It is done. In addition to the dust collectors 9 and 11 having the filter, a cyclone, an electric dust collector, or the like can be used.
[0027]
Next, operation | movement of the artificial lightweight aggregate manufacturing apparatus 1 which has the said structure is demonstrated.
Pellet P is supplied from the pellet supply unit 3 into the kiln 2, and the pellet P passes through the drying region, the sintering region, the foaming region, and the cooling region in the kiln 2 heated by the flame of the burner 4. 5 is discharged as a product.
[0028]
Here, the fine particles of the aggregate particles generated along with the rotation of the kiln 2 reach the foaming temperature region and soften in the vicinity thereof to cause a fusion action between the aggregates and the shell surface of the kiln. In order to prevent this fusion, limestone L as a fusion prevention material is blown through the fusion prevention material supply facility 6. Then, fusion is avoided and the aggregate A as a product is discharged from the aggregate discharge portion 5. In addition, the particle size of the limestone L blown into the kiln 2 should just be about 5 mm or less, and if it is a particle size which does not cause troubles, such as clogging, in a transportation system and a supply / spray apparatus, there will be no problem.
[0029]
The limestone L blown into the kiln 2 is decomposed into quick lime (CaO) and carbon dioxide (CO 2 ), and a part of the quick lime Q 1 is introduced into the dust collector 11 through the duct 10 together with the combustion air flow in the kiln 2. The exhaust gas G1 is recovered by the dust collector 11 and released to the atmosphere.
[0030]
On the other hand, a part of quicklime generated from the used limestone L adheres to the surface of the aggregate A and is discharged from the aggregate discharge section 5 to the product side. The quicklime Q2 adhering to the aggregate A is sieved by the sieve 7 a, rides on the air current, is introduced into the dust collector 9 through the duct 7, and is collected by the dust collector 9. The exhaust gas G2 is released to the atmosphere.
[0031]
The quicklime Q1 and Q2 collected by the dust collector 9 and the dust collector 11 can be effectively used as a product. Moreover, although the powder collected by the dust collector 11 in the exhaust system contains fine powder of pellets P, it can be used as a soil solidifying material or a soil improving material. Moreover, if CaO content is 40% or more, it can be used as an aggregating agent or a solidifying agent. In addition, by reducing the generation amount of fine powder originating from the raw material aggregate, high-quality quicklime can be by-produced also on the exhaust system side.
[0032]
In addition, since a part of quicklime generated from the limestone L adheres to the surface of the aggregate A and is discharged to the product side as described above, the surface of the product aggregate has a content of 0.01 to 0.05%. A certain amount of quicklime remains. Therefore, although this aggregate cannot be used for the use which dislikes an alkaline condition, it can be used as a concrete aggregate without any problem.
[0033]
Further, when limestone is used as an anti-fusing material, the limestone is thermally dissociated in the kiln to generate carbon dioxide and quick lime, and energy is consumed at that time. For example, when 3% of limestone is used for 1 ton of raw material aggregate, energy of about 12600 kcal is theoretically consumed, but it is not a problem when compared with the energy consumption of the entire system. is there.
[0034]
Furthermore, if carbon dioxide gas generated by the above reaction is released to the atmosphere, it may cause global warming, which may be undesirable for the environment, but in the long term, quick lime is carbonated and is equivalent to the amount dissociated. Because carbon dioxide is absorbed, there is no problem.
[0035]
【The invention's effect】
As described above, according to the present invention, the use of an inexpensive and reusable anti-fusing material reduces the manufacturing cost and eliminates the need for disposal of the anti-fusing material. It is possible to provide a manufacturing method.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a preferred example of an apparatus for carrying out a method for producing an artificial lightweight aggregate according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Artificial lightweight aggregate manufacturing apparatus 2 Kiln 3 Pellet supply part 4 Burner 5 Aggregate discharge part 6 Fusion prevention material supply equipment 7 Separation apparatus 7a Sieve 8 Duct 9 Dust collector 10 Duct 11 Dust collector

Claims (5)

ロータリーキルンを用いて人工軽量骨材を製造する方法において、
原料骨材の微粉による骨材同士または骨材とロータリーキルンのシェル面との融着を防止するための融着防止材に石灰石を使用することを特徴とする人工軽量骨材の製造方法。In a method of manufacturing an artificial lightweight aggregate using a rotary kiln,
A method for producing an artificial lightweight aggregate, characterized in that limestone is used as an anti-fusing material for preventing fusion between aggregates of raw material aggregates or between the aggregate and the shell surface of the rotary kiln. 原料骨材に対する前記石灰石の添加量を０．５乃至１０重量％としたことを特徴とする請求項１記載の人工軽量骨材の製造方法。The method for producing an artificial lightweight aggregate according to claim 1, wherein the amount of the limestone added to the raw material aggregate is 0.5 to 10% by weight. 前記ロータリーキルンによって焼成された骨材の表面に付着した生石灰を除去する工程を含むことを特徴とする請求項１または２記載の人工軽量骨材の製造方法。The method for producing an artificial lightweight aggregate according to claim 1 or 2, further comprising a step of removing quick lime adhering to a surface of the aggregate fired by the rotary kiln. 前記ロータリーキルンに投入される前記石灰石の粒径を５ｍｍ以下としたことを特徴とする請求項１または２記載の人工軽量骨材の製造方法。The method for producing an artificial lightweight aggregate according to claim 1 or 2, wherein the limestone charged into the rotary kiln has a particle size of 5 mm or less. ロータリーキルンを用いて人工軽量骨材を製造する方法において、
原料骨材の微粉による骨材同士または骨材とロータリーキルンのシェル面との融着を防止するため、融着防止材をロータリーキルン内に吹き込み、吹き込んだ融着防止材から生じた固体状物質を該ロータリーキルンの排気系、または該ロータリーキルンから排出される骨材の表面から回収して再利用することを特徴とする人工軽量骨材の製造方法。In a method of manufacturing an artificial lightweight aggregate using a rotary kiln,
In order to prevent fusion between the aggregates by the fine powder of the raw material aggregate or between the aggregate and the shell surface of the rotary kiln, an anti-fusing material is blown into the rotary kiln, and the solid substance generated from the blown anti-fusing material is A method for producing an artificial lightweight aggregate, characterized in that it is recovered from the exhaust system of a rotary kiln or the surface of aggregate discharged from the rotary kiln and reused.
JP2001062769A 2001-03-07 2001-03-07 Manufacturing method of artificial lightweight aggregate Expired - Fee Related JP4430835B2 (en)

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