JP4351744B2 - Refractory using aluminum dross residual ash processed product as raw material - Google Patents

Description

【００１１】
この結果によれば、プラズマ処理によって、残灰中の窒素、塩素及びＰｂ、Ｃｄ、Ｓｎ等の重金属は殆ど分離除去され、逆にアルミナ含有率は９０重量％以上に高められていることが分かる。実験によれば、高アルミナ化は約１８００℃以上の加熱によって促進される。処理残灰の高アルミナ化によって、耐火物原料としての利用に希望が持たれるようになった。
【００１２】
（耐火れんが）
試作した耐火れんがは、鉄鋼精錬用取鍋等に使用される不焼成ハイアルミナれんがで、その原料配合比率を表２に示す。
【００１３】
【表２】

【００１４】
比較品は上記種類のれんがの市販品と品質を類似させたものであり、試作品は、比較品における焼成ボーキサイトの配合比率９０重量％のうち３０重量％を処理残灰で置換したものである。表２に示す各原料を混練した後、油圧プレスによって７００ｋｇｆ／ｃｍ²で成形した。その後、１１０℃で１０時間乾燥した後、２℃／ｍｉｎで昇温し、５００℃で５時間保持後、炉冷して不焼成れんがの試験片とした。
【００１５】
この試験片の基本性状を把握する目的で実施した試験の項目、及び試験の結果として得られた一般物理的性質、圧縮強さ、残存線膨張収縮率を、それぞれ表３、表４に示す。
【００１６】
【表３】

【００１７】
【表４】

【００１８】
表４の一般物理的質、圧縮強さに関する試験の結果では、処理残灰３０％置換品は比較品とほぼ等しい値を示し、両者は同程度の特性を有することが分かった。残存線膨張収縮率では、両者で対照的な性質が見られるが、鉄鋼用途においては、１％程度の残存膨張性を必要とする場合が多く、この点では、処理残灰３０％置換品の方が優れている。
【００１９】
スラグ浸食試験については、溶融炉用スラグを用い、１３００℃、５０時間の条件で実施した結果、浸食は僅かで両者の間に差はみられず、特に処理残灰３０％置換品の方が変質層が少なく良好な結果が得られた。しかし、鉄鋼用スラグを用い、１５００℃、１０時間の条件で実施した結果は、処理残灰３０％置換品の方が浸食量が僅かに多いことが分かった。
【００２０】
（不定形耐火物）
試作した不定形耐火物は、各種窯炉向けの最高使用温度１７００℃の緻密質ハイアルミナキャスタブルで、その原料配合比率を表５に示す。
【００２１】
【表５】

【００２２】
比較品は上記種類のキャスタブルの市販品と品質を類似させたものであり、試作品は、比較品における焼成ボーキサイトの配合比率８１重量％のうち３０重量％を処理残灰で置換したものである。表５に示す各原料を試験用ミキサーで５分間混練し、ＪＩＳ標準軟度のキャスタブル混練物を得た。この混練物を所定形状の金型に鋳込み成形し、一昼夜養生後、ハイアルミナキャスタブルの試験片とした。
【００２３】
この試験片に対して実施した試験の項目、及びこれに対応して得られた線変化率、圧縮強さの結果を、それぞれ表６、図２、図３に示す。
【００２４】
【表６】

【００２５】
図２の線変化率においては、温度の上昇とともに両者はほぼ同様に推移している。図３の圧縮強さにおいては、処理残灰３０％置換品の方が高温になるほど僅かに低下している。
【００２６】
上記のとおり、耐火れんが、不定形耐火物それぞれについて、処理残灰３０％を焼成ボーキサイトと置換して配合したものは、市販品の許容レベルには達しており、処理残灰を耐火物原料として利用することは十分に可能であると考えられる。上記試験では、各耐火物とも、処理残灰と化学組成的に類似する焼成ボーキサイトの配合のうちの３０％を処理残灰で置換したが、処理残灰の品質によってはさらに配合比率を増加することもできる。また、処理残灰はアルミナ系耐火物に限らず、高アルミナという特性を活かして例えばシャモット系耐火物にも原料として配合可能である。上記から明らかなように、いずれの耐火物に対しても、その耐火性能及び配合比率の上で、処理残灰のアルミナ含有率は高いほどよいが、少なくとも９０重量％であることが望ましい。
【００２７】
さらに、処理残灰を繊維（ウール）状に加工して、アルミナウール、セラミックウールとした場合についても検討したところ、市販品と比較して遜色のない製品を作ることができることが分かった。また、ロックウール、グラスウールの代替えとしては、品質的には優れているが、価格の面から、耐火性が要求される用途への需要が見込まれる。
【図面の簡単な説明】
【図１】 残灰の処理に使用したアークプラズマ炉の概略縦断面図である。
【図２】 不定形耐火物の線変化率試験の結果を示すグラフである。
【図３】 不定形耐火物の圧縮強さ試験の結果を示すグラフである。
【符号の説明】
１…アークチャンバー、２…プラズマ発生用トーチ、３…投入装置、４…カーボンるつぼ、５…陽極、６…水冷陽極板、７…取鍋、８…耐火材、９…のぞき窓。[0001]
BACKGROUND OF THE INVENTION
The present invention uses as raw materials a product obtained by reusing aluminum dross ash generated when aluminum ingots and aluminum scrap are melted as a resource, particularly a processed product obtained by melting aluminum dross ash by arc plasma heating. It relates to refractories.
[0002]
[Prior art]
Aluminum dross residual ash (hereinafter referred to as residual ash) is the aluminum remaining in the slag generated during melting of aluminum bullion and aluminum scrap. Say the remnants. About 250,000 tons of this residual ash is generated annually, and a part of it is used as a flux during steel refining, but the rest is disposed of by managed landfill. However, the residual ash contains components that may adversely affect the environment, such as nitrogen compounds, chlorine compounds, and heavy metals.
[0003]
As a means for removing these harmful components from the residual ash and detoxifying them, the melting treatment by arc plasma heating has a remarkable effect compared with the conventional water treatment method and combustion method, as disclosed in JP-A-8-281239. It has been revealed.
[0004]
[Problems to be solved by the invention]
By the way, especially in recent years, the recycling of aluminum has expanded and the amount of generated residual ash has increased. On the other hand, the landfill site has been tightened and the processing cost has been increasing. Therefore, the present invention aims to recover the cost required for the detoxification treatment by reusing the detoxified residual ash not as a cheap cement raw material or aggregate but as a refractory raw material with higher added value. completed.
[0005]
[Means for Solving the Problems]
The inventors have conducted research on arc plasma treatment of residual ash, and as a result, if the residual ash is heated and melted by arc plasma and held at 1800 to 2000 ° C. for 2 to 4 hours, nitrogen compounds, chlorine compounds, and heavy metals can be obtained. It was found that almost all of them were separated and the alumina content reached 90% by weight or more. Based on this discovery, we succeeded in reusing the residual ash-treated product as a refractory raw material utilizing the characteristics of alumina. The present invention is a refractory formed by blending, as a raw material, a processed product obtained by melting aluminum dross residual ash by arc plasma heating (hereinafter referred to as processed residual ash), and the refractory is an alumina refractory, The raw material is obtained by melting the residual ash at a melting temperature of 1800 to 2000 ° C. for 2 to 4 hours. In the alumina refractory according to the present invention, a part of the calcined bauxite can be replaced with the raw material. In the case of constituting the alumina refractory according to the present invention, it is preferable to employ a raw material having an alumina content of at least 90% by weight.
[0006]
[Operation and effect of the invention]
By melting the residual ash by arc plasma heating, nitrogen compounds and heavy metals contained in the residual ash are separated and detoxified, in particular, chlorine compounds are removed and the content of alumina is increased. It is done. For this reason, the treated residual ash can be recycled as a refractory raw material with higher added value by utilizing the characteristic of containing high alumina, not the conventional cement raw material or aggregate .
[0007]
When the treated ash is used as a raw material for the alumina-based refractory, it is preferable to mix with the calcined bauxite similar in chemical composition to the treated ash. Moreover, it is desirable that the alumina content of the treated residual ash is at least 90% by weight regardless of the type of the refractory in terms of the fire resistance performance and the blending ratio of the target refractory.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
First, refractory bricks and amorphous refractories were made using the treated residual ash as an alternative to calcined bauxite produced by calcining natural bauxite.
[0009]
(Residual ash treatment)
The residual ash was processed in the arc plasma melting furnace shown in FIG. This furnace uses a DC transfer type argon plasma with a rated output of 60 kW. The inside of the arc chamber 1 was continuously charged with residual ash from the charging device 3 under an atmospheric condition of 1.015 × 10 ⁵ Pa and melted in a carbon crucible 4 installed at the bottom of the arc chamber 1. The treated residual ash was analyzed by EPMA, ICP-AES, atomic absorption analysis, and thermal conductivity method. Table 1 shows the components of the residual ash before and after the plasma treatment.
[0010]
[Table 1]

[0011]
According to this result, it can be seen that nitrogen, chlorine and heavy metals such as Pb, Cd and Sn in the residual ash are almost separated and removed by the plasma treatment, and conversely, the alumina content is increased to 90% by weight or more. . According to experiments, high aluminization is promoted by heating at about 1800 ° C. or higher. Due to the high-aluminaization of the treated residual ash, there is hope for its use as a refractory raw material.
[0012]
(Fireproof brick)
The prototype refractory brick is a non-fired high alumina brick used for a steel refining ladle or the like.
[0013]
[Table 2]

[0014]
The comparative product is similar in quality to the commercial products of the above-mentioned types of bricks, and the prototype is a product in which 30% by weight of the blended proportion of burned bauxite in the comparative product is replaced by treated residual ash. . Each material shown in Table 2 was kneaded and then molded at 700 kgf / cm ² by a hydraulic press. Then, after drying at 110 ° C. for 10 hours, the temperature was increased at 2 ° C./min, held at 500 ° C. for 5 hours, and then cooled in a furnace to obtain an unfired brick test piece.
[0015]
Tables 3 and 4 show the items of the test conducted for the purpose of grasping the basic properties of the test piece, and the general physical properties, compressive strength, and residual linear expansion / contraction rate obtained as a result of the test, respectively.
[0016]
[Table 3]

[0017]
[Table 4]

[0018]
As a result of the test on the general physical quality and compressive strength in Table 4, it was found that the treated residual ash 30% substituted product showed almost the same value as the comparative product, and both had the same characteristics. In the residual linear expansion / shrinkage ratio, a contrasting property is seen between the two, but in steel applications, a residual expansion of about 1% is often required. Is better.
[0019]
The slag erosion test was carried out using melting furnace slag under the conditions of 1300 ° C and 50 hours. As a result, erosion was slight and there was no difference between them. Good results were obtained with few altered layers. However, as a result of using steel slag under the conditions of 1500 ° C. and 10 hours, it was found that the treated ash 30% replacement product had a slightly larger amount of erosion.
[0020]
(Unshaped refractory)
The prototype refractory is a dense high-alumina castable with a maximum use temperature of 1700 ° C. for various kilns.
[0021]
[Table 5]

[0022]
The comparative product is similar in quality to the above-mentioned commercially available castable products, and the prototype product is obtained by replacing 30% by weight of the processed bashsite blending ratio of 81% by weight with the processed residual ash. . Each raw material shown in Table 5 was kneaded for 5 minutes with a test mixer to obtain a JIS standard soft castable kneaded product. This kneaded material was cast into a predetermined mold, and after curing for a whole day and night, a high alumina castable test piece was obtained.
[0023]
Table 6, FIG. 2, and FIG. 3 show the items of the test performed on the test piece, and the results of the linear change rate and the compressive strength obtained corresponding thereto.
[0024]
[Table 6]

[0025]
In the line change rate of FIG. 2, both of them change substantially in the same manner as the temperature increases. In the compressive strength of FIG. 3, the treatment residual ash 30% replacement product slightly decreases as the temperature rises.
[0026]
As mentioned above, for each of the refractory bricks that are irregular shaped refractories, 30% of the treated residual ash is replaced with calcined bauxite. It is considered possible to use it sufficiently. In the above test, in each refractory, 30% of the composition of the calcined bauxite similar in chemical composition to the treated residue ash was replaced with the treated residue ash, but the compounding ratio is further increased depending on the quality of the treated residue ash. You can also. Further, the treated residual ash is not limited to alumina refractories, and can be blended as a raw material in, for example, chamotte refractories utilizing the characteristics of high alumina. As is apparent from the above, for any refractory, the higher the alumina content of the treated residual ash, the better, in view of its fire resistance and blending ratio, but it is preferably at least 90% by weight.
[0027]
Furthermore, when processing residual ash was processed into a fiber (wool) shape to make alumina wool and ceramic wool, it was found that a product comparable to a commercial product could be made. Further, as an alternative to rock wool and glass wool, although it is excellent in quality, demand for applications requiring fire resistance is expected from the viewpoint of price.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view of an arc plasma furnace used for treating residual ash.
FIG. 2 is a graph showing the results of a line change rate test of an amorphous refractory.
FIG. 3 is a graph showing the results of a compressive strength test of an amorphous refractory.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Arc chamber, 2 ... Plasma generating torch, 3 ... Loading device, 4 ... Carbon crucible, 5 ... Anode, 6 ... Water-cooled anode plate, 7 ... Ladle, 8 ... Refractory material, 9 ... Peep window.

Claims (2)

Characterized in that the alumina content of the treated residual ash that aluminum dross residual ash and molten processed by arc plasma heating was regenerated by 2-4 hour hold molten processed at a melt temperature of 1800 to 2000 ° C. is blended with at least 90 wt% of the raw materials Alumina-based refractories. The alumina-based refractory according to claim 1, wherein the raw material is substituted into a part of the calcined bauxite.

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