JPS60105642A - Purification of acetone - Google Patents
Purification of acetoneInfo
- Publication number
- JPS60105642A JPS60105642A JP21324983A JP21324983A JPS60105642A JP S60105642 A JPS60105642 A JP S60105642A JP 21324983 A JP21324983 A JP 21324983A JP 21324983 A JP21324983 A JP 21324983A JP S60105642 A JPS60105642 A JP S60105642A
- Authority
- JP
- Japan
- Prior art keywords
- acetone
- aqueous solution
- acid
- solution
- water
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 title claims abstract description 144
- 238000000746 purification Methods 0.000 title claims 2
- 239000002253 acid Substances 0.000 claims abstract description 20
- 239000003513 alkali Substances 0.000 claims abstract description 10
- 239000012535 impurity Substances 0.000 claims abstract description 5
- 238000000034 method Methods 0.000 claims description 8
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 abstract description 45
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 25
- 239000007864 aqueous solution Substances 0.000 abstract description 24
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 abstract description 15
- 239000000243 solution Substances 0.000 abstract description 10
- 238000004519 manufacturing process Methods 0.000 abstract description 7
- 229920006221 acetate fiber Polymers 0.000 abstract description 2
- 239000006227 byproduct Substances 0.000 abstract 1
- 150000001875 compounds Chemical class 0.000 abstract 1
- 239000000126 substance Substances 0.000 abstract 1
- OZXIZRZFGJZWBF-UHFFFAOYSA-N 1,3,5-trimethyl-2-(2,4,6-trimethylphenoxy)benzene Chemical compound CC1=CC(C)=CC(C)=C1OC1=C(C)C=C(C)C=C1C OZXIZRZFGJZWBF-UHFFFAOYSA-N 0.000 description 9
- 238000004821 distillation Methods 0.000 description 9
- SHOJXDKTYKFBRD-UHFFFAOYSA-N mesityl oxide Natural products CC(C)=CC(C)=O SHOJXDKTYKFBRD-UHFFFAOYSA-N 0.000 description 9
- 238000010992 reflux Methods 0.000 description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 229920000742 Cotton Polymers 0.000 description 4
- SWXVUIWOUIDPGS-UHFFFAOYSA-N diacetone alcohol Chemical compound CC(=O)CC(C)(C)O SWXVUIWOUIDPGS-UHFFFAOYSA-N 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000009835 boiling Methods 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 238000006386 neutralization reaction Methods 0.000 description 3
- 238000009987 spinning Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- BWLBGMIXKSTLSX-UHFFFAOYSA-N 2-hydroxyisobutyric acid Chemical group CC(C)(O)C(O)=O BWLBGMIXKSTLSX-UHFFFAOYSA-N 0.000 description 1
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 235000019253 formic acid Nutrition 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- OVARTBFNCCXQKS-UHFFFAOYSA-N propan-2-one;hydrate Chemical compound O.CC(C)=O OVARTBFNCCXQKS-UHFFFAOYSA-N 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- SFKTYEXKZXBQRQ-UHFFFAOYSA-J thorium(4+);tetrahydroxide Chemical compound [OH-].[OH-].[OH-].[OH-].[Th+4] SFKTYEXKZXBQRQ-UHFFFAOYSA-J 0.000 description 1
- 210000004916 vomit Anatomy 0.000 description 1
- 230000008673 vomiting Effects 0.000 description 1
Landscapes
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
Description
【発明の詳細な説明】
本発明は、不純物として酸を含むアセトン水溶液をアル
カリで中和処理した後、精製する方法に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for purifying an acetone aqueous solution containing an acid as an impurity after neutralizing it with an alkali.
アセテ−１−繊本１１製に５は、酢酸綿を少量の水を含
むアセトンてｔｔ８解し”Ｃ紡糸している。紡糸工程で
は熱風によりアセトンを蒸発させ、アセトーンを含んだ
空気はアセ１ン回収工程に導かれる。Acete-1-Senbon 11-made 5 is made by dissolving acetic acid cotton in acetone containing a small amount of water and spinning it into "C" yarn.In the spinning process, the acetone is evaporated with hot air, and the air containing acetone is evaporated with acetone. is guided to the collection process.
アセ１−ン回収装置１′ｌとして一般的に使用されてい
る方法は、アセ１ンを含んだ空気を水と接触させ、アセ
トンを水に吸収させるか、或いは活性肖ｆｐシ゛θ）叫
１ｙγね１でアセトンを嘔着きせる方法である。A commonly used method for acetone recovery equipment is to bring air containing acetone into contact with water and allow the acetone to be absorbed into the water, or to absorb the acetone into the water. This is a method to make the acetone vomit with 1.
水で吸収させたアセトンは、そのまま蒸留工程（・こ送
られ、アセトンと水とに分離され、アセトンは再び溶剤
として循環使用される。活性炭。The acetone absorbed with water is directly sent to the distillation process (・) where it is separated into acetone and water, and the acetone is recycled and used again as a solvent.Activated carbon.
を使用してアセトンを吸着させる方法では、スチームな
どでアセトンの脱着を行ないアセトン水溶液として回収
するのが一般的である。その後の操作は水でアセトンを
吸着させた場合と同様である。In the method of adsorbing acetone using acetone, it is common to desorb the acetone using steam or the like and recover it as an acetone aqueous solution. The subsequent operations are similar to those for adsorbing acetone with water.
蒸留操作により塔頂から水分１〜ｌ０ＷＬ％を含むアセ
トンが回収されるが、このアセトン中には酢酸換算とし
て酸が数十〜数百１ｌｌＨｎ混入してくる。このような
アセトンを、酢酸綿の溶解溶剤として再使用すると、製
品であるアセテート繊維に酸臭が生じ問題トこなる。Through the distillation operation, acetone containing 1 to 10 WL% of water is recovered from the top of the column, but several tens to hundreds of liters of acid (in terms of acetic acid) are mixed into this acetone. If such acetone is reused as a dissolving solvent for acetic acid cotton, the product, acetate fiber, will develop an acid odor, causing problems.
この原因は、酢酸綿をアセトンと水の混合溶剤で溶解し
たり、紡糸工程で熱風によりアセトンを蒸発させる工程
で、酢酸綿が加水分解し酢酸が遊離して、それがアセト
ン回収工程に導かれるためである。その他には、アセト
ンを活性炭で吸着さ仕、スチームで脱着する工程で活性
炭が触媒として働き、アセトンの一部がギ酸や５酢酸な
どに変わることも原因として挙げられる一０以上の原因
により、アセトンと水の分離を行なう蒸留塔への仕込液
中に酸が酢酸として０８０１１）ｐ Ｉ１１含まれてく
る。The cause of this is that when acetic acid cotton is dissolved in a mixed solvent of acetone and water, or when acetone is evaporated with hot air during the spinning process, acetic acid cotton is hydrolyzed and acetic acid is liberated, which is then led to the acetone recovery process. It's for a reason. In addition, the activated carbon acts as a catalyst in the process of adsorbing acetone with activated carbon and desorbing it with steam, converting some of the acetone into formic acid and pentaacetic acid. Acid is contained in the form of acetic acid in the feed liquid to the distillation column that separates water and water.
したがって、一般に行なわれている対策は、蒸留塔への
ｆ１込液にアルカリを過剰に添加し、有機酸を塩に変え
、塔底液である水に溶解させ蒸留塔より↑１１出し、留
出液である回収アセトン側に留出しないようにすること
である。事実そうすることで、酸が回収アセ１ンに混入
することを十分防ぐことが０■能であるが、新たに別の
問題が生じてくる。仕込液であるアセトン水溶液に中和
処理するためにアルカリを添加すると、アセトンがアｌ
レドール縮合しジアセトンアルコールになり、加熱など
により脱水されメシチルオキシドが生成する。ジアセト
ンアルコール（沸点１６８℃）は水と比べてかなり沸点
差があるので分離は容易であるが、水とメシチルオ・キ
シド（沸点１３０℃）は最低共沸し、その共沸温度は９
２℃であり、留出液である回収アセトンにメシチルオキ
シドが水と共沸してメンチルオキシドが混入し易すく、
酸の場合と同様に臭いの問題が生じ、必ずメンチルオキ
シドが回収アセトン中に入らないように蒸留条件を選定
しなければならない。即ち、メシチルオキシドは水と共
沸するため留出液である回収アセトン中の水分を必要以
上に必なくし、回収アセトンの純度を上げなければなら
なく、そのためには還流比を非常に高める必要がある。Therefore, the commonly used countermeasure is to add an excessive amount of alkali to the f1 charge to the distillation column, convert the organic acid into a salt, dissolve it in water, which is the bottom liquid, and discharge it from the distillation column. The aim is to prevent it from distilling into the recovered acetone side, which is a liquid. In fact, by doing so, it is possible to sufficiently prevent acid from being mixed into the recovered acetone, but a new problem arises. When an alkali is added to the acetone aqueous solution that is the charging solution for neutralization, the acetone becomes alkaline.
Redol condenses to form diacetone alcohol, which is then dehydrated by heating to produce mesityl oxide. Diacetone alcohol (boiling point 168°C) has a considerable boiling point difference compared to water, so separation is easy, but water and mesityl oxide (boiling point 130°C) have the lowest azeotrope, and their azeotropic temperature is 9.
2°C, mesityl oxide azeotropes with water and menthyl oxide easily mixes into the recovered acetone, which is the distillate.
As with acids, odor problems arise, and distillation conditions must be selected to ensure that menthyl oxide does not enter the recovered acetone. In other words, since mesityl oxide azeotropes with water, it is necessary to eliminate more water than necessary in the recovered acetone, which is the distillate, to increase the purity of the recovered acetone, and for this purpose, the reflux ratio must be extremely high. There is.
しかし、そうすることは多大なエネルギーを消費し、経
済性が極端に悪くなる。However, doing so consumes a large amount of energy and is extremely uneconomical.
本発明者らは、このような問題点を解決する為、鋭意検
討した結果、アセトン水溶液に添加するアルカリ量によ
り、メンチルオキシドの生成量が大きく変わることをつ
きとめ、アセトン水溶液のｐＨをコントロールすること
で、極力メシチルオキシドの生成を押えることができる
という新しい知Ｑを見出し本発明に至ったのである。In order to solve these problems, the inventors of the present invention have conducted intensive studies and found that the amount of menthyl oxide produced varies greatly depending on the amount of alkali added to the acetone aqueous solution. Therefore, we discovered a new knowledge Q that can suppress the production of mesityl oxide as much as possible, leading to the present invention.
アセ１−ンと水の比率が４５ ： ５５ （ＷＬ％）に
なるようにアセトン水溶液を調整し、この水溶液に酸と
して酢酸をＱ、 ｌ ｗＬ％になるように添加した。ア
ルカリとして５ｗｔ％の水酸化ナトリウム水溶液を使用
し、アセトン水溶液を所定のＩ）Ｈにしたｔ＆、１ｅ丸
型フラスコにコンデンサーをセットした装置を用いてこ
のアセトン水溶液を全還流で２時間ｔ１］）騰加熱した
。加熱後、液相をガスクロ分４７１法でメンチルオキシ
ドの分析を行ない、図１に示した１１１１ とメンチル
オキシドの生成の関係を↑１）だ。An acetone aqueous solution was adjusted so that the ratio of acetone to water was 45:55 (WL%), and acetic acid was added as an acid to this aqueous solution so that the ratio was Q,1wL%. Using a 5 wt % aqueous sodium hydroxide solution as an alkali, the acetone aqueous solution was adjusted to the specified I)H, and the acetone aqueous solution was refluxed for 2 hours using a device in which a condenser was set in a 1e round flask. It was heated to a high temperature. After heating, the liquid phase was analyzed for menthyl oxide using the gas chromatography method, and the relationship between 1111 shown in Figure 1 and the formation of menthyl oxide was ↑1).
図１から明らかなように、メシチルオキシドの生成が最
も少なくなるｐＨは１０１τ１近であり、その鎮からｐ
Ｈが小さくなっても大きくなってもメシチルオキシドの
生成が大いに増加する。As is clear from Figure 1, the pH at which the production of mesityl oxide is the least is near 101τ1, and from that point
Whether H is decreased or increased, the production of mesityl oxide increases greatly.
即ち、不純物として酸を含むアセトン水溶液をアルカリ
で中和したｆ＆、精製処理するに際して、メンチルオキ
シドの生成を極力、少なくするためにはアセトン水溶液
のｐＨを実Ｊｌｌ白りに（より〜１１にすればよいとり
・う新しく１知見を得た。。In other words, when an acetone aqueous solution containing an acid as an impurity is neutralized with an alkali and purified, the pH of the acetone aqueous solution should be adjusted to a level of about 11% to minimize the production of menthyl oxide. I learned a new thing about the bird bird.
したがって、従来のようｔこメシチルオキシドが蒸留塔
の留出液である回収アセトンをこ混入することを防ぐた
めに、塔頂還流量をカーなＩ〕多くし、回収アセトン中
の水分を少なくシ、アセトン純度を必要以上に高くする
必要力；なくなった。Therefore, in order to prevent mesityl oxide from mixing with the recovered acetone, which is the distillate of the distillation column, the amount of reflux at the top of the column is increased to reduce the water content in the recovered acetone. , the need to increase acetone purity higher than necessary is eliminated.
つまり、従来より相当に還流量を少なくして水分１〜ｌ
Ｑ ｗｔ％を含む所定の純度をもつ回１又アセトン中
にもメンチルオキシド
流を減らした分だけ、省エネ！レギーをこな一フ経済性
が非常によくなった。In other words, the amount of reflux is considerably reduced compared to conventional methods, and water
Save energy by reducing the flow of menthyl oxide in acetone with a specified purity including Q wt%! The economy of playing leggies has become much better.
以下、本発明を実施例及び比較ｍｌ ｔこつり・て説明
するが、本発明はこれによって１吸定さＪするものでは
ない。Hereinafter, the present invention will be explained in detail using examples and comparative examples, but the present invention is not limited to these examples.
実施例 １
アセトンと水の比率が４５：５５（％ＶＬ％）になるよ
うにアセトン水溶液な＃ｌｌ ！１！し、この水溶液に
酸として酢酸を０． １ ｗＬ％ｔこなるように添加し
た。アルカリとして５ ｗｔ％の水酸化す１リウム水溶
液を使用し、アセトン水溶液のｐＨが９．９になるまで
中和処理した。Example 1 Prepare an acetone aqueous solution so that the ratio of acetone and water is 45:55 (%VL%)! 1! Then, 0.0% acetic acid was added to this aqueous solution as an acid. 1 wL%t was added. A 5 wt % sodium hydroxide aqueous solution was used as the alkali, and neutralization was performed until the pH of the acetone aqueous solution became 9.9.
この中＋１１処理済みのアセトン水ｍ液をガラス製４０
段オールダーショウ塔を用いて蒸留実験を行なった。操
作条件として還流比Ｒ／Ｄをα５にして蒸留すると留出
液の組成は、アセトンＷ外に水分２．１１ｖＬ％、メシ
チルオキシド３１）凹１、酸（酢酸として） １８ ｐ
ｐ＋ｎ、が含まれていた。缶出液中にはアセトンがｌ
Ｏｐｐ＋ｎであった。尚、この回収アセトンは循環使用
が可能であ〕た。Among these, +11 treated acetone water m solution was made of glass 40
Distillation experiments were carried out using a stage Oldershaw column. When distilled with a reflux ratio R/D of α5 as the operating condition, the composition of the distillate is: acetone W, water 2.11 vL%, mesityl oxide 31) 1, acid (as acetic acid) 18 p
p+n, was included. There is l of acetone in the bottom liquid.
It was Opp+n. Note that this recovered acetone could be recycled.
比較例 １
実施例１と同じ酢酸を含むアセトン水溶液及び水酸化す
トリウム水溶液を使用しｐＨが１２．９になる才で中和
処理した。Comparative Example 1 The same acetone aqueous solution containing acetic acid and thorium hydroxide aqueous solution as in Example 1 were used to neutralize the product until the pH reached 12.9.
この中イ１１処理済みのアセトン水溶液を実施例１と同
じ装置を使用し、還流比Ｒ／Ｄを０．８にし、他の条件
は実施例１と同じで蒸留を行なった。留出液の組成は、
アセトン以外ｔこ水分Ｌ６ｗｔ％、メンチルオキシド２
１ｐｐｍ酸（酢酸として） １６ ｐｐｎ＋が含まれて
いた。缶出液中ｔこはアセトンが１２ ｐｐｍであった
。尚、この回収アセトンはメンチルオキシドの臭いのた
め再使用できなかった。The acetone aqueous solution that had been treated with Naka-11 was distilled using the same apparatus as in Example 1, with the reflux ratio R/D being 0.8, and under the same conditions as in Example 1. The composition of the distillate is
Other than acetone, moisture L 6wt%, menthyl oxide 2
Contained 1 ppm acid (as acetic acid) 16 ppn+. The acetone content in the bottoms was 12 ppm. Note that this recovered acetone could not be reused due to the odor of menthyl oxide.
次に還流比Ｒ／Ｄを１０にして蒸留を行なった。留出液
の組成はアセトン以外に水分１．３ ｗｔ％、メンチル
オキシド２９ｐＨ１，酸（酢酸として） １３ ｐｐｍ
が含まれていた。缶出液中にはアセトンが１０ ｐｐｎ
＋であった。この回収アセトンは再使用が可能であった
が、実施例１と比較して還流比が２倍となり、エネルギ
ー消費もかなり多く経済性が悪くなる。Next, distillation was carried out at a reflux ratio R/D of 10. In addition to acetone, the composition of the distillate is 1.3 wt% water, 29 pH 1 menthyl oxide, and 13 ppm acid (as acetic acid).
was included. There is 10 ppn of acetone in the bottom liquor.
It was +. Although this recovered acetone could be reused, the reflux ratio was twice that of Example 1, and the energy consumption was considerably large, making it uneconomical.
比較例 ２
実施例１と同じ酢酸を含むアセトン水ｍ液を使用したが
、水酸化ナトリウム水溶液での中和処理は行なわなかっ
た。Comparative Example 2 The same acetone aqueous solution containing acetic acid as in Example 1 was used, but neutralization treatment with an aqueous sodium hydroxide solution was not performed.
この中和処理を全く行なわなかったアセトン水溶液を実
施例１と同じ装置を使用し、還流比Ｒ／Ｄを０．８にし
、他の条件は実施例１と同じで蒸留を行なった。留出液
の組成はアセトン以外に水分ｌ ５ ｗＬ％、メンチル
オキシド６Ｎ）１ｎ、酸（＾１酸として） １２２ ｐ
ｐｍが含まれていた。缶出液中にはアセトンガｌ ｌ
１ｌｌＩＩ１１であった。尚、この回収アセトンは酸臭
のため再使用できなかフた。This aqueous acetone solution, which had not been neutralized at all, was distilled using the same apparatus as in Example 1, with a reflux ratio R/D of 0.8, and other conditions being the same as in Example 1. The composition of the distillate is, in addition to acetone, water 1 5 wL%, menthyl oxide 6N) 1n, and acid (as ^1 acid) 122p.
PM was included. There is acetonate in the bottom liquor.
It was 1llII11. However, this recovered acetone could not be reused due to its acid odor.
第１図は、酸を含むアセトン水溶液を水酸化ナトリウム
水溶ｉ１Ｖで中和処理したとき、アセトン水溶液の１市
とメンチルオキシドの生成の関係を示したものである
。
窮１図
ＨFigure 1 shows the relationship between the concentration of the acetone aqueous solution and the production of menthyl oxide when the acetone aqueous solution containing an acid is neutralized with an aqueous solution of sodium hydroxide. 1st picture H
Claims (1)
してｐＨ９〜１１とした後、精製処理することを特徴と
するアセトンの精製方法。1. A method for purifying acetone, which comprises adding an alkali to an aqueous acetone solution containing an acid as an impurity to adjust the pH to 9 to 11, and then performing purification treatment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21324983A JPS60105642A (en) | 1983-11-15 | 1983-11-15 | Purification of acetone |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21324983A JPS60105642A (en) | 1983-11-15 | 1983-11-15 | Purification of acetone |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS60105642A true JPS60105642A (en) | 1985-06-11 |
Family
ID=16635972
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP21324983A Pending JPS60105642A (en) | 1983-11-15 | 1983-11-15 | Purification of acetone |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60105642A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04327347A (en) * | 1991-04-30 | 1992-11-16 | Kawasaki Steel Corp | Treatment of molten metal in tundish |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56158725A (en) * | 1980-05-12 | 1981-12-07 | Mitsui Toatsu Chem Inc | Purifying method of ketone |
-
1983
- 1983-11-15 JP JP21324983A patent/JPS60105642A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56158725A (en) * | 1980-05-12 | 1981-12-07 | Mitsui Toatsu Chem Inc | Purifying method of ketone |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04327347A (en) * | 1991-04-30 | 1992-11-16 | Kawasaki Steel Corp | Treatment of molten metal in tundish |
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