JP2012170867A - METHOD FOR SEPARATING AND RECOVERING SiC FROM USED REFRACTORY - Google Patents
METHOD FOR SEPARATING AND RECOVERING SiC FROM USED REFRACTORY Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 22
- 239000003945 anionic surfactant Substances 0.000 claims abstract description 24
- 239000007864 aqueous solution Substances 0.000 claims abstract description 17
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 63
- 238000005188 flotation Methods 0.000 claims description 24
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical group [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 claims description 9
- 239000002994 raw material Substances 0.000 abstract description 16
- 239000000047 product Substances 0.000 abstract description 8
- 239000002244 precipitate Substances 0.000 abstract description 6
- 239000000243 solution Substances 0.000 abstract description 2
- 239000002245 particle Substances 0.000 description 38
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 31
- 239000004088 foaming agent Substances 0.000 description 15
- 239000011819 refractory material Substances 0.000 description 15
- 241000628997 Flos Species 0.000 description 13
- 239000000463 material Substances 0.000 description 13
- 239000007787 solid Substances 0.000 description 11
- 239000002699 waste material Substances 0.000 description 11
- 239000003093 cationic surfactant Substances 0.000 description 10
- 238000000926 separation method Methods 0.000 description 10
- 238000011084 recovery Methods 0.000 description 9
- 239000002893 slag Substances 0.000 description 9
- YIWUKEYIRIRTPP-UHFFFAOYSA-N 2-ethylhexan-1-ol Chemical compound CCCCC(CC)CO YIWUKEYIRIRTPP-UHFFFAOYSA-N 0.000 description 8
- 230000002209 hydrophobic effect Effects 0.000 description 8
- 239000000126 substance Substances 0.000 description 8
- 239000004094 surface-active agent Substances 0.000 description 7
- 238000002474 experimental method Methods 0.000 description 6
- 239000000706 filtrate Substances 0.000 description 5
- 238000007667 floating Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 229960000686 benzalkonium chloride Drugs 0.000 description 3
- CADWTSSKOVRVJC-UHFFFAOYSA-N benzyl(dimethyl)azanium;chloride Chemical compound [Cl-].C[NH+](C)CC1=CC=CC=C1 CADWTSSKOVRVJC-UHFFFAOYSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 125000001165 hydrophobic group Chemical group 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000007935 neutral effect Effects 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- 239000000725 suspension Substances 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 230000005389 magnetism Effects 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 229910001018 Cast iron Inorganic materials 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 230000006399 behavior Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000011449 brick Substances 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 230000005660 hydrophilic surface Effects 0.000 description 1
- 230000005661 hydrophobic surface Effects 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 238000011002 quantification Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 125000000542 sulfonic acid group Chemical group 0.000 description 1
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Abstract
Description
本発明は、使用済みのＳｉＣ−Ａｌ２Ｏ３系耐火物からＳｉＣを分離回収する方法に関する。 The present invention relates to a method for separating and recovering SiC from a used SiC-Al 2 O 3 refractory.
鉄鋼製造プロセスでは、製銑工程や製鋼工程の設備で多くの耐火物が使用されている。使用される耐火物の約半分は、操業中に溶融スラグや溶融メタルと接触することで損耗する。残存した使用済みの耐火物は、新しい耐火物を施工する際に解体され、屑となる。この耐火物屑の一部は、耐火物原料としてリサイクル使用されているが、大部分の耐火物屑は、その組成に関わりなくセメント原料や路盤材、土木用材料などとして用いられている。 In the steel manufacturing process, many refractories are used in the iron making process and the steel making process. About half of the refractory used is worn by contact with molten slag and molten metal during operation. The remaining used refractory is dismantled when a new refractory is applied and becomes waste. A part of the refractory waste is recycled as a refractory raw material, but most of the refractory waste is used as a cement raw material, a roadbed material, a civil engineering material or the like regardless of its composition.
鉄鋼製造プロセスの諸設備で使用される耐火物としては、例えば、転炉に使用されるＭｇＯ−Ｃ系耐火物、タンディッシュや取鍋に使用されるHigh−Ａｌ２Ｏ３系耐火物、高炉用スラグライン材（高炉鋳床の溶銑樋）やトーピードカーに使用されるＳｉＣ−Ａｌ２Ｏ３系耐火物などがある。このなかでＳｉＣ−Ａｌ２Ｏ３系耐火物は、耐火物原料のなかで最も高価であるＳｉＣを８割程度含むことから、このＳｉＣを耐火物原料として再利用できれば、原料コストの大幅な削減が可能となる。
従来、使用済み耐火物のリサイクル技術に関しては、特許文献１〜５に示されるような種々の提案がなされているが、いずれも使用済み耐火物から付着スラグと変質層を除去し、破砕して耐火物原料にリサイクルする方法やリサイクル耐火物に関するものである。
Examples of refractories used in various steel manufacturing process facilities include, for example, MgO-C refractories used in converters, High-Al 2 O 3 refractories used in tundish and ladle, and blast furnaces. There are SiC slag line materials (molten blast furnace cast iron) and SiC-Al 2 O 3 refractories used for torpedo cars. Of these, SiC-Al 2 O 3 refractories contain about 80% of SiC, which is the most expensive refractory raw material, so if this SiC can be reused as a refractory raw material, the raw material cost will be greatly reduced. Is possible.
Conventionally, regarding the recycling technology of used refractories, various proposals such as those shown in
しかし、付着スラグと変質層を除去して破砕した耐火物屑は、元の耐火物と同じものであり、耐火物の原料である骨材や各成分の粉体に戻ったわけではない。したがって、耐火物原料としては品質が劣るため、耐火物屑を配合する量は制限される。また、原料の一部に耐火物屑を用いた耐火物は、新規原料から作る耐火物と比べ寿命が劣ってしまう。 However, the refractory debris that has been crushed by removing the attached slag and the altered layer is the same as the original refractory, and has not returned to the aggregate that is the raw material of the refractory or the powder of each component. Therefore, since quality is inferior as a refractory raw material, the quantity which mix | blends refractory waste is restrict | limited. In addition, a refractory using refractory waste as a part of the raw material has a shorter life than a refractory made from a new raw material.
したがって本発明の目的は、以上のような従来技術の課題を解決し、使用済みのＳｉＣ−Ａｌ２Ｏ３系耐火物から、耐火物原料として通常のＳｉＣ原料と同様に使用できるＳｉＣを高純度で分離回収することができる方法を提供することにある。 Therefore, an object of the present invention is to solve the prior art problems described above, the spent SiC-Al 2 O 3 based refractories, SiC of high purity which can be used like a normal SiC raw material as a refractory raw material It is to provide a method that can be separated and recovered by the above method.
上記課題を解決するための本発明の要旨は以下のとおりである。
［1］使用済みのＳｉＣ−Ａｌ２Ｏ３系耐火物を粉砕し、その粉砕物を陰イオン界面活性剤を添加した水溶液に投入して浮遊選鉱法によりＡｌ２Ｏ３を浮上分離させ、沈殿物のＳｉＣを分離回収することを特徴とする使用済み耐火物からのＳｉＣ分離回収方法。
［2］上記［1］の方法において、陰イオン界面活性剤がドデシル硫酸ナトリウムであることを特徴とする使用済み耐火物からのＳｉＣ分離回収方法。
The gist of the present invention for solving the above problems is as follows.
[1] Used SiC-Al 2 O 3 refractory is pulverized, and the pulverized product is put into an aqueous solution to which an anionic surfactant is added, and Al 2 O 3 is floated and separated by a flotation method, and then precipitated. A method for separating and recovering SiC from a used refractory, characterized by separating and recovering SiC of the product.
[2] A method for separating and recovering SiC from a used refractory, wherein the anionic surfactant is sodium dodecyl sulfate in the method of [1].
本発明によれば、使用済みのＳｉＣ−Ａｌ２Ｏ３系耐火物からＳｉＣを分離回収するに当たり、特定の水溶液を用いた浮遊選鉱法を利用して耐火物からＡｌ２Ｏ３を分離することで、ＳｉＣを高純度で分離回収することができる。このため回収したＳｉＣを耐火物原料にリサイクルすることで、耐火物の原料コストを大幅に削減することができ、また、耐火物屑の廃棄量や廃棄コストの削減も図ることができる。 According to the present invention, when separating and recovering SiC from a used SiC-Al 2 O 3 refractory, the Al 2 O 3 is separated from the refractory using a flotation method using a specific aqueous solution. Thus, SiC can be separated and recovered with high purity. Therefore, by recycling the collected SiC to the refractory raw material, the raw material cost of the refractory can be significantly reduced, and the amount of refractory waste discarded and the cost of disposal can be reduced.
本発明は、使用済みのＳｉＣ−Ａｌ２Ｏ３系耐火物（耐火物屑）を粉砕し、その粉砕物を陰イオン界面活性剤を添加した水溶液に投入して浮遊選鉱法によりＡｌ２Ｏ３を浮上分離させ、沈殿物のＳｉＣを分離回収するものである。上記浮遊選鉱では水槽内を上昇する気泡にＡｌ２Ｏ３を付着させて浮上させ、この浮上した泡にトラップされたＡｌ２Ｏ３を分離し、沈殿したＳｉＣを回収する。
ここで、ＳｉＣ−Ａｌ２Ｏ３系耐火物とは、ＳｉＣ、Ａｌ２Ｏ３を主原料とするレンガまたは不定形耐火物のことである。
In the present invention, a used SiC-Al 2 O 3 refractory (refractory waste) is pulverized, and the pulverized product is put into an aqueous solution to which an anionic surfactant is added, and Al 2 O 3 is added by a flotation method. Are floated and separated, and the SiC of the precipitate is separated and recovered. In the flotation floated by attaching Al 2 O 3 in bubbles rising through the water tank, the Al 2 O 3, which is trapped in the floating froth is separated and recovered precipitated SiC.
Here, the SiC—Al 2 O 3 -based refractory is a brick or an amorphous refractory made mainly of SiC and Al 2 O 3 .
上記のように本発明は、使用済みのＳｉＣ−Ａｌ２Ｏ３系耐火物の粉砕物を浮遊選鉱法を利用してＳｉＣとＡｌ２Ｏ３に分離するものである。分離対象であるＳｉＣとＡｌ２Ｏ３は比重差が０．９と小さく磁性を持たないため、比重や磁気による分離方法は適用できなかった。本発明は、ＳｉＣとＡｌ２Ｏ３の粒子表面の性状差を調べ、分離方法を確立したものである。
浮遊選鉱法は、親水性・疎水性という粒子表面の性質と気泡を利用した固々分離法である。図１に浮遊選鉱法による固々分離の原理を示す。まず、分離対象である微細な固体粒子を水中に投入し、撹拌翼で撹拌することにより水中に懸濁させ、そこに散気装置により気泡を導入する。すると、疎水性の表面をもつ固体粒子（以下、「疎水性粒子」という）だけが選択的に気泡表面に付着し、気泡の浮力により付着物として浮上する。このように疎水性粒子が付着した状態で浮上した泡をフロスという。通常、フロス形成を維持するための助剤として、気泡剤が添加される。一方、親水性の表面をもつ固体粒子（以下、「親水性粒子」という）は気泡に付着せず、自重により沈降（沈殿）する。これらを個別に回収することで、親水性粒子と疎水性粒子の分離が可能となる。
As described above, the present invention separates a used pulverized SiC-Al 2 O 3 refractory into SiC and Al 2 O 3 using a flotation method. Since SiC and Al 2 O 3 to be separated have a small specific gravity difference of 0.9 and do not have magnetism, separation methods based on specific gravity and magnetism cannot be applied. In the present invention, the property difference between the particle surfaces of SiC and Al 2 O 3 is examined, and a separation method is established.
The flotation method is a solid separation method that utilizes the properties of the particle surface, hydrophilic and hydrophobic, and bubbles. Fig. 1 shows the principle of solid separation by flotation. First, fine solid particles to be separated are put into water, stirred with a stirring blade to be suspended in water, and air bubbles are introduced therein by an air diffuser. Then, only solid particles having a hydrophobic surface (hereinafter referred to as “hydrophobic particles”) selectively adhere to the surface of the bubbles and float as adhering substances due to the buoyancy of the bubbles. The foam that floats in the state where the hydrophobic particles are attached is called floss. Usually, a foaming agent is added as an auxiliary agent for maintaining floss formation. On the other hand, solid particles having a hydrophilic surface (hereinafter referred to as “hydrophilic particles”) do not adhere to bubbles but settle (precipitate) by their own weight. By separately collecting these, hydrophilic particles and hydrophobic particles can be separated.
しかし、ＳｉＣとＡｌ２Ｏ３の場合、そのままではどちらの粒子も親水性であり、水中では気泡に付着して浮上することはない。
ＳｉＣとＡｌ２Ｏ３では、ゼータ電位が異なる挙動を示す。ゼータ電位は液体と固体の接する界面に発生している界面電荷を簡易的に定量化したものである。図２に、水溶液のｐＨとＳｉＣ粒子およびＡｌ２Ｏ３粒子のゼータ電位との関係を示す。界面電荷は液体のｐＨ環境により変化し、例えば、ｐＨが中性時のＳｉＣの界面電荷は負、Ａｌ２Ｏ３の界面電荷は正となる。このように固体粒子の表面電位の正負が異なる場合、溶液への界面活性剤の添加により、一方の固体粒子を疎水性にすることができる。
However, in the case of SiC and Al 2 O 3 , both particles are hydrophilic as they are and do not float by adhering to bubbles in water.
SiC and Al 2 O 3 exhibit different behaviors with different zeta potentials. The zeta potential is a simple quantification of the interfacial charge generated at the interface between the liquid and solid. FIG. 2 shows the relationship between the pH of the aqueous solution and the zeta potential of SiC particles and Al 2 O 3 particles. The interface charge changes depending on the pH environment of the liquid. For example, when the pH is neutral, the interface charge of SiC is negative and the interface charge of Al 2 O 3 is positive. When the positive and negative surface potentials of the solid particles are different as described above, one solid particle can be made hydrophobic by adding a surfactant to the solution.
界面活性剤は、炭化水素からなる疎水基、カルボキシル基やスルホン酸基などの親水基で構成されている。そして、水中で界面活性剤の親水基が陽イオンに解離するものを陽イオン界面活性剤、親水基が陰イオンに解離するものを陰イオン界面活性剤と呼ぶ。
図３は、水中で陰イオン界面活性剤がＡｌ２Ｏ３粒子に電気的に吸着してＡｌ２Ｏ３粒子が疎水化し、この疎水化したＡｌ２Ｏ３粒子が気泡に付着して浮上する原理（想定される原理）を示している。水溶液のｐＨが中性では、Ａｌ２Ｏ３粒子表面は正に帯電している。陰イオン界面活性剤が水中に溶解すると、解離して親水基は負に帯電する。すると、正に帯電したＡｌ２Ｏ３粒子表面に、負に帯電した陰イオン界面活性剤の親水基が吸着する。Ａｌ２Ｏ３粒子は陰イオン界面活性剤の疎水基で覆われ、表面が疎水化された状態になる。この結果、疎水化されたＡｌ２Ｏ３粒子は気泡に付着し、気泡とともに浮上する。以上が、陰イオン界面活性剤を用いた場合に想定されるＡｌ２Ｏ３粒子の浮上分離の原理である。
逆に、水溶液のｐＨが中性では、ＳｉＣ粒子表面は負に帯電している。陽イオン界面活性剤が水中に溶解すると、解離して親水基は正に帯電する。すると、負に帯電したＳｉＣ粒子表面に、正に帯電した陽イオン界面活性剤の親水基が吸着する。ＳｉＣ粒子は陽イオン界面活性剤の疎水基で覆われ、表面が疎水化された状態になる。この結果、疎水化されたＳｉＣ粒子は気泡に付着し、気泡とともに浮上する。以上が、陽イオン界面活性剤を用いた場合に想定されるＳｉＣ粒子の浮上分離の原理である。
The surfactant is composed of a hydrophobic group made of hydrocarbon, a hydrophilic group such as a carboxyl group or a sulfonic acid group. And what dissociates the hydrophilic group of a surfactant into a cation in water is called a cationic surfactant, and what dissociates a hydrophilic group into an anion is called an anionic surfactant.
3, the anionic surfactant in water electrically adsorbed to Al 2 O 3 particles are hydrophobized in Al 2 O 3 particles, the hydrophobized Al 2 O 3 particles floats attached to the bubble The principle (the assumed principle) is shown. When the pH of the aqueous solution is neutral, the surface of the Al 2 O 3 particles is positively charged. When the anionic surfactant dissolves in water, it dissociates and the hydrophilic group becomes negatively charged. Then, the hydrophilic group of the negatively charged anionic surfactant is adsorbed on the surface of the positively charged Al 2 O 3 particles. The Al 2 O 3 particles are covered with the hydrophobic group of the anionic surfactant, and the surface becomes hydrophobic. As a result, the hydrophobized Al 2 O 3 particles adhere to the bubbles and float with the bubbles. The above is the principle of floating separation of Al 2 O 3 particles assumed when an anionic surfactant is used.
Conversely, when the pH of the aqueous solution is neutral, the surface of the SiC particles is negatively charged. When the cationic surfactant is dissolved in water, it dissociates and the hydrophilic group becomes positively charged. Then, the hydrophilic group of the positively charged cationic surfactant is adsorbed on the surface of the negatively charged SiC particles. The SiC particles are covered with the hydrophobic group of the cationic surfactant, and the surface becomes hydrophobic. As a result, the hydrophobicized SiC particles adhere to the bubbles and float with the bubbles. The above is the principle of flotation separation of SiC particles assumed when a cationic surfactant is used.
浮遊選鉱法によりＳｉＣ−Ａｌ２Ｏ３系耐火物の粉砕物からＳｉＣを効率的に分離回収するための条件、具体的には、（i）Ａｌ２Ｏ３、ＳｉＣのいずれを浮上させて分離した方がよいのか、（ii）陽イオン界面活性剤と陰イオン界面活性剤のいずれがＳｉＣとＡｌ２Ｏ３の分離に適しているのか、（iii）浮遊選鉱する際の気泡剤の濃度、などについて、以下のような実験と検討を行った。
ＳｉＣとＡｌ２Ｏ３は不定形耐火物の原料となる粉状のものを用いた。界面活性剤には、安価で安全性が高く入手しやすいものとして、陰イオン界面活性剤はドデシル硫酸ナトリウムを、陽イオン界面活性剤は塩化ベンザルコニウムを、それぞれ用いた。また、フロス生成に必要な気泡剤としては２−エチルヘキサノールを用いた。水溶液の水はイオン交換水を用いた。
Conditions for efficiently separating and recovering SiC from pulverized SiC-Al 2 O 3 refractories by the flotation method, specifically (i) by separating either Al 2 O 3 or SiC (Ii) Which of cationic surfactant and anionic surfactant is suitable for separation of SiC and Al 2 O 3 , (iii) Concentration of foaming agent during flotation, The following experiments and examinations were conducted.
For SiC and Al 2 O 3, powdery materials used as raw materials for the amorphous refractory were used. As the surfactant, an anionic surfactant used was sodium dodecyl sulfate, and a cationic surfactant used was benzalkonium chloride as an inexpensive and highly available product. Moreover, 2-ethylhexanol was used as a foaming agent required for froth production. Ion exchange water was used as the water of the aqueous solution.
図４に浮遊選鉱実験に用いた装置の概略を示す。内径２００ｍｍφの円筒状水槽はアクリル製であり、その底部に散気装置としてステンレス鋼製の多孔板（孔径φ０．３ｍｍ、孔数３７個）を設けた。この散気装置には、コンプレッサから圧縮空気が供給され、この空気が多孔板から吹き出すことにより気泡が生成する。
水槽にイオン交換水４．５Ｌ（ｐＨ６．２〜８．２，水温１９．２〜２０．０℃）を入れ、気泡剤を添加した。水２００ｍｌを入れたビーカーに粒径７４μｍ以下のＳｉＣとＡｌ２Ｏ３の粉末各５０ｇと界面活性剤を添加し、マグネチックスターラーにて１００ｒｐｍ、１０分間撹拌した。この液を水槽に投入し、コンプレッサから散気装置へ所定のガス流量と圧力（０．２ＭＰａ）にて送風することで、所定時間浮遊選鉱を行った。その後、フロスを回収することで浮上物（固体粒子）を回収し、沈殿物は排水後水槽底部に残ったものを回収した。また、排水した液に残る懸濁物を回収し、沈殿物の一部として扱った。これら回収物は熱風乾燥機で乾燥させた後、秤量および化学分析を行った。
Fig. 4 shows the outline of the equipment used in the flotation experiment. The cylindrical water tank with an inner diameter of 200 mmφ is made of acrylic, and a stainless steel porous plate (hole diameter φ0.3 mm, number of holes 37) is provided at the bottom as a diffuser. The air diffuser is supplied with compressed air from a compressor, and air is blown out of the perforated plate to generate bubbles.
Ion-exchanged water 4.5 L (pH 6.2 to 8.2, water temperature 19.2 to 20.0 ° C.) was placed in a water tank, and a foaming agent was added. In a beaker containing 200 ml of water, 50 g of SiC and Al 2 O 3 powder each having a particle size of 74 μm or less and a surfactant were added, and the mixture was stirred with a magnetic stirrer at 100 rpm for 10 minutes. This liquid was put into a water tank and floated with a predetermined gas flow rate and pressure (0.2 MPa) from a compressor to a diffuser for a predetermined time. Thereafter, the floating material (solid particles) was recovered by recovering the floss, and the deposit was recovered from the bottom of the water tank after drainage. In addition, the suspension remaining in the drained liquid was collected and treated as part of the precipitate. These recovered materials were dried with a hot air dryer and then weighed and subjected to chemical analysis.
浮上物の回収率は下記（1）式から、分離したＳｉＣとＡｌ２Ｏ３の回収率は下記（2）、（3）式からそれぞれ算出した。回収物中の各成分の質量は、回収物の量、化学分析値から求めた。
［浮上物の回収率（％）］＝{［回収した浮上物質量（ｇ）］／[投入物質量（ｇ）]}×１００ …（1）
［ＳｉＣの回収率（％）］＝{［回収した浮上物（又はろ過物）中のＳｉＣ質量（ｇ）］／[投入したＳｉＣ質量（ｇ）]}×１００ …（2）
［Ａｌ２Ｏ３の回収率（％）］＝{［回収した浮上物（又はろ過物）中のＡｌ２Ｏ３質量（ｇ）］／[投入したＡｌ２Ｏ３質量（ｇ）]}×１００ …（3）
The recovery rate of the levitated matter was calculated from the following formula (1), and the recovery rates of the separated SiC and Al 2 O 3 were calculated from the following formulas (2) and (3), respectively. The mass of each component in the recovered material was determined from the amount of recovered material and the chemical analysis value.
[Recovery rate of levitated matter (%)] = {[Amount of collected levitated substance (g)] / [Amount of input substance (g)]} × 100 (1)
[SiC recovery rate (%)] = {[SiC mass (g) in recovered levitated matter (or filtrate)] / [SiC mass (g)]} × 100 (2)
[Al 2 O 3 recovery rate (%)] = {[Al 2 O 3 mass (g) in recovered levitated matter (or filtrate)] / [Al 2 O 3 mass (g) charged]} × 100 (3)
フロスの生成量と厚みは、浮上物の回収に重要であるので、フロスの厚さに及ぼす気泡剤濃度とガス流量の影響を調べた。その結果を図５に示す。この実験では、イオン交換水に気泡剤（２−エチルヘキサノール）のみを添加し、生成するフロスの厚みを測定した。気泡剤濃度を０ｐｐｍ（無添加）、２８ｐｐｍ、５５ｐｐｍ、１００ｐｐｍの４水準とした。図５によれば、気泡剤濃度が２８ｐｐｍ以上であればフロスが生成されること、また、フロスの厚さはガス流量で決まり、気泡剤濃度は影響しないことが判る。したがって、気泡剤濃度は２８ｐｐｍで十分である。 Since the amount and thickness of the floss are important for the recovery of the levitated matter, the effects of the foaming agent concentration and the gas flow rate on the floss thickness were investigated. The result is shown in FIG. In this experiment, only the foaming agent (2-ethylhexanol) was added to ion-exchanged water, and the thickness of the generated floss was measured. The foaming agent concentration was set to four levels of 0 ppm (no addition), 28 ppm, 55 ppm, and 100 ppm. According to FIG. 5, it can be seen that if the foaming agent concentration is 28 ppm or more, floss is generated, and the thickness of the floss is determined by the gas flow rate, and the foaming agent concentration has no effect. Therefore, 28 ppm is sufficient for the foaming agent concentration.
図６に、陽イオン界面活性剤（塩化ベンザルコニウム）を用いた場合と、陰イオン界面活性剤（ドデシル硫酸ナトリウム）を用いた場合について、浮上物中でのＳｉＣとＡｌ２Ｏ３の回収率を示す。各界面活性剤は、水槽内で濃度が５×１０−５mol／Ｌになるよう投入した。気泡剤の濃度は２８ｐｐｍとし、コンプレッサから散気装置へのガス流量を７．５Ｌ／minとし、２０分間連続的に浮遊選鉱を行った。ＳｉＣを疎水化して浮上、Ａｌ２Ｏ３を沈殿させて分離することを狙って、陽イオン界面活性剤である塩化ベンザルコニウムを添加した。しかし、ＳｉＣとＡｌ２Ｏ３が同時に浮上し、ＳｉＣとＡｌ２Ｏ３が分離できなかった。一方、陰イオン界面活性剤であるドデシル硫酸ナトリウムを使用した場合には、Ａｌ２Ｏ３は６３％浮上したのに対し、ＳｉＣは３％しか浮上しなかった。すなわち、陰イオン界面活性剤（ドデシル硫酸ナトリウム）を用いるとＡｌ２Ｏ３のみを選択的に浮上分離できることが判った。 FIG. 6 shows the recovery of SiC and Al 2 O 3 in the levitated matter using a cationic surfactant (benzalkonium chloride) and an anionic surfactant (sodium dodecyl sulfate). Indicates the rate. Each surfactant was added so as to have a concentration of 5 × 10 −5 mol / L in the water tank. The concentration of the foaming agent was 28 ppm, the gas flow rate from the compressor to the diffuser was 7.5 L / min, and flotation was continuously performed for 20 minutes. Benzalkonium chloride, which is a cationic surfactant, was added with the aim of hydrophobizing SiC to float and precipitating and separating Al 2 O 3 . However, SiC and Al 2 O 3 floated simultaneously, and SiC and Al 2 O 3 could not be separated. On the other hand, when sodium dodecyl sulfate as an anionic surfactant was used, Al 2 O 3 floated 63%, whereas SiC floated only 3%. That is, it was found that when an anionic surfactant (sodium dodecyl sulfate) is used, only Al 2 O 3 can be selectively levitated and separated.
以上の実験結果から、使用済みのＳｉＣ−Ａｌ２Ｏ３系耐火物からＳｉＣを分離回収するには、耐火物屑を粉砕し、その粉砕物を陰イオン界面活性剤を添加した水溶液に投入して浮遊選鉱法によりＡｌ２Ｏ３を浮上分離させ、沈殿物のＳｉＣを分離回収すればよいこと、また、陰イオン界面活性剤としては、特にドデシル硫酸ナトリウムが適していることを確認できた。 From the above experimental results, in order to separate and recover SiC from the used SiC-Al 2 O 3 refractory, refractory waste is pulverized and the pulverized product is put into an aqueous solution to which an anionic surfactant is added. Thus, it was confirmed that Al 2 O 3 was floated and separated by the flotation method, and the precipitated SiC was separated and recovered, and sodium dodecyl sulfate was particularly suitable as the anionic surfactant.
以下、本発明を実施する際の好ましい条件について説明する。
使用済みのＳｉＣ−Ａｌ２Ｏ３系耐火物を粉砕する場合、事前にスラグが付着した部分を除去して、粒径０．３ｍｍ以下に粉砕することが好ましい。浮遊選鉱法は気泡に付着させて分離するため、粒子径は小さいほうが浮上し易く、望ましくは粒径０．１５ｍｍ以下まで粉砕したほうがよい。
陰イオン界面活性剤は、分離性能、安全性、価格の点から、ドデシル硫酸ナトリウムが適している。また、水溶液中での陰イオン界面活性剤の濃度は５×１０−５mol／Ｌ以上が好ましい。
気泡剤としては、２−エチルヘキサノールなどが好ましく、水溶液中での濃度は２８ｐｐｍ以上が好ましい。
浮遊選鉱装置としては、後述する図８に示すように、水槽と、その底部に設置され、水槽内の水溶液に気泡を散気する散気装置と、水槽内の水溶液を撹拌する撹拌装置など備えたものを用いるのが好ましい。
Hereinafter, preferable conditions for carrying out the present invention will be described.
When grinding the spent SiC-Al 2 O 3 based refractories, to remove the pre-slug is attached to the portion, it is preferable to pulverize the following particle size 0.3 mm. Since the flotation method attaches to bubbles and separates them, the smaller the particle size, the easier it is to float, and it is better to pulverize to a particle size of 0.15 mm or less.
As the anionic surfactant, sodium dodecyl sulfate is suitable from the viewpoint of separation performance, safety and price. Further, the concentration of the anionic surfactant in the aqueous solution is preferably 5 × 10 −5 mol / L or more.
As the foaming agent, 2-ethylhexanol is preferable, and the concentration in the aqueous solution is preferably 28 ppm or more.
As shown in FIG. 8 to be described later, the flotation apparatus includes a water tank, an air diffuser installed at the bottom of the water tank to diffuse bubbles into the aqueous solution in the water tank, and a stirring device for stirring the aqueous solution in the water tank. Is preferably used.
使用済みのＳｉＣ−Ａｌ２Ｏ３系耐火物（高炉用スラグライン材の耐火物屑）を回収し、耐火物に付着したスラグと耐火物中にスラグが浸透した部分を取り除き、粉砕機で粒径０．３ｍｍ以下に粉砕した。この粉砕物の化学成分は、図７に示すようにＳｉＣ：７６質量％、Ａｌ２Ｏ３：２１質量％であった。
図８に使用した浮遊選鉱装置の概略を示す。この装置では、水槽に１５ｍ３の水を入れ、撹拌翼を２０ｒｐｍで回転させて水を撹拌しつつ、底部に設置された散気装置にコンプレッサから圧縮空気が供給され、その多孔板（孔径φ０．３ｍｍ、孔数３７００個）から空気が吹き出すことにより気泡が生成する。そして、この気泡に水溶液中の疎水性粒子が付着することでフロスが生成する。
陰イオン界面活性剤としてドデシル硫酸ナトリウムを、気泡剤として２−エチルヘキサノールをそれぞれ用い、水槽内での陰イオン界面活性剤の濃度は５×１０−５mol／Ｌとし、気泡剤の濃度は２８ｐｐｍとした。水溶液の温度は２１．０℃、ｐＨ６．８であった。コンプレッサから散気装置へのガス流量を１０００Ｌ／min、ガス圧力を０．２ＭＰａとして浮遊選鉱を行った。
Collect used SiC-Al 2 O 3 refractory (refractory waste from blast furnace slag line material), remove the slag adhering to the refractory and the part where the slag penetrated into the refractory, It grind | pulverized to the diameter of 0.3 mm or less. The chemical components of the pulverized product were SiC: 76% by mass and Al 2 O 3 : 21% by mass as shown in FIG.
FIG. 8 shows an outline of the flotation apparatus used. In this apparatus, 15 m 3 of water is put into a water tank, and the stirring blade is rotated at 20 rpm, and the water is stirred. Air bubbles are generated by blowing out air from 3 mm and 3700 holes). Then, floss is generated by attaching hydrophobic particles in the aqueous solution to the bubbles.
Using sodium dodecyl sulfate as the anionic surfactant and 2-ethylhexanol as the foaming agent, the concentration of the anionic surfactant in the water tank was 5 × 10 −5 mol / L, and the concentration of the foaming agent was 28 ppm. It was. The temperature of the aqueous solution was 21.0 ° C. and pH 6.8. Flotation was performed with a gas flow rate from the compressor to the diffuser of 1000 L / min and a gas pressure of 0.2 MPa.
水槽内に耐火物屑の粉砕物を２０ｋｇ／ｍｉｎの供給速度で連続的に供給し、生成したフロスを回収して浮上物を回収した。生成したフロスの厚みは１０ｃｍ程度であった。耐火物屑の粉砕物を５分間連続的に供給した後、供給を停止し、１分間フロスの回収のみを行うことを１時間繰り返した。水槽内の懸濁液を沈殿物とともに一旦排水し、ベルトフィルターでろ過後、水は水槽に戻した。ろ過物は回収後、乾燥した。
浮上物とろ過物（沈殿物＋懸濁液中の固形分）の回収量と化学成分を分析した結果を図９に示すが、浮上物はＡｌ２Ｏ３：７２質量％、ろ過物はＳｉＣ：９５質量％で回収できた。浮上物にはＳｉＣが２０質量％含まれるが、高純度のＳｉＣを回収するためには、粉砕後もＡｌ２Ｏ３と分離できないＳｉＣも浮上分離するほうがよい。
The ground material of the refractory waste was continuously supplied into the water tank at a supply rate of 20 kg / min, and the generated floss was recovered to recover the floating material. The thickness of the generated floss was about 10 cm. After continuously supplying pulverized refractory waste for 5 minutes, the supply was stopped and only the recovery of floss for 1 minute was repeated for 1 hour. The suspension in the water tank was once drained together with the precipitate, filtered with a belt filter, and the water was returned to the water tank. The filtrate was collected and dried.
FIG. 9 shows the results of analyzing the recovered amount and chemical components of the floated product and filtrate (precipitate + solid content in the suspension). The floated material is Al 2 O 3 : 72% by mass, and the filtrate is SiC. : 95% by mass was recovered. The levitated material contains 20% by mass of SiC. In order to recover high-purity SiC, it is better to levitate and separate SiC that cannot be separated from Al 2 O 3 even after pulverization.
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