JPS61130430A - Cleaning method of molten al or al alloy refined by gaseous chlorine - Google Patents

Abstract

PURPOSE:To remove efficiently impurities from molten Al or Al alloy refined by gaseous chlorine and to clean the molten metal by filtering the molten metal by pulverous sodium chloride or potassium chloride as a filter aid. CONSTITUTION:The pulverous sodium chloride and/or potassium chloride is added at about 0.005-0.1wt% as the filter aid to the molten Al or Al alloy refined by gaseous chlorine and an inert gas is blown thereto to stir the molten metal and to disperse uniformly said sodium chloride and/or potassium chloride. The grain size of the sodium chloride, etc. is properly selected according to the pore size of a filter consisting of a porous refractory material, etc. The molten metal is preferably filtered after the filter is precoated by circulating the molten metal dispersed with the above-mentioned filter aid circulated in the initial stage of filtration. The fine impurities in the molten metal are thus effectively removed and the decrease in cleanliness is hardly obviated even if the slight chlorides mentioned above enter the molten metal subjected to the filtration.

Description

【発明の詳細な説明】 〔産業上の利用分舒〕 本発明は、塩素ガスで精錬されたＡｌ又はＡｌ合金（以
下Ａ工合金で代表する）溶湯中の不純物を効率良く除去
し清浄化する方法に関するものである。[Detailed Description of the Invention] [Industrial Application] The present invention efficiently removes and cleans impurities in molten Al or Al alloy (hereinafter referred to as A alloy) refined with chlorine gas. It is about the method.

〔従来の技術〕[Conventional technology]

Ａｌ合金溶湯には原料やＡｌ合金スクラップ等の溶製原
料から混入してくる不純物や溶製工程で混入及び新たに
発生する不純物がかなり含まれて詣り、これらの不純物
は様々の製品欠陥を生ずる原因となる。その為Ａｌ合金
の鋳造に当たっては、Ａｌ合金溶湯を塩素ガス或はフラ
ックスで精錬することによって不純物を除去し、更に微
細な不純物は多孔質耐火材からなるフィルターでＦ去し
清浄化した後鋳造工程へ送っている。Molten Al alloy contains a considerable amount of impurities that come from raw materials and molten raw materials such as Al alloy scrap, and impurities that are mixed in or newly generated during the smelting process, and these impurities cause various product defects. Cause. Therefore, when casting Al alloys, impurities are removed by refining the molten Al alloy with chlorine gas or flux, and fine impurities are cleaned by removing F with a filter made of porous refractory material before the casting process. I am sending it to

〔発明が解決しようとする問題点〕[Problem that the invention seeks to solve]

本発明者等もＡｌ合金の溶解−精錬−濾過−鋳造−２次
加工についてかねてより工業的に実施しているが、そこ
での経験から、同一のＰ材を使用し同一の濾過条件を設
定した場合でもＡｌ合金溶湯の精錬法によっては濾過後
の清浄度に顕著な違いが生じてくることがあるのを知っ
た。即ち同−濾過条件を設定した場合でも、フラックス
精錬を行ったＡｌ合金溶湯では高清浄度が得られるが、
塩素ガス精錬を行ったＡｌ合金溶湯では清浄度がかなり
低く、不純物に起因する製品欠陥が現われるのは殆んど
の場合前者（塩素ガス精錬を行ったもの）である。The present inventors have also been industrially conducting melting, refining, filtration, casting, and secondary processing of Al alloys for some time, and based on their experience, they used the same P material and set the same filtration conditions. I learned that even in some cases, there may be a noticeable difference in the cleanliness after filtration depending on the refining method of the molten Al alloy. That is, even when the same filtration conditions are set, high cleanliness can be obtained with flux-refined Al alloy molten metal.
The cleanliness of Al alloy molten metal that has been subjected to chlorine gas refining is quite low, and in most cases product defects due to impurities appear in the former (those that have been subjected to chlorine gas refining).

本発明はこうした状況のもとで、特に塩素ガス精錬を行
ったＡｌ合金溶湯を対象として、不純物を効果的に除去
し清浄度を高めることのできる技術を提供しようとする
ものである。Under these circumstances, the present invention aims to provide a technology that can effectively remove impurities and improve the cleanliness of molten Al alloys that have been subjected to chlorine gas refining.

〔問題点を解決する為の手段〕[Means for solving problems]

本発明は塩素ガスにより精錬されたＡｌ合金溶湯中の不
純物を除去するに当たり、微粉状の塩化ナトリウム及び
／又は塩化カリウムを濾過助剤としてＦ遇するところに
要旨が存在する。The gist of the present invention is to use finely powdered sodium chloride and/or potassium chloride as a filter aid when removing impurities from a molten Al alloy refined with chlorine gas.

〔作用〕[Effect]

前述の如く精錬法によって濾過挙動が著しく異なる理由
を追求した結果、次の様な事実が確認された。即ち精錬
後のＡｌ合金溶湯の濾過用炉材としては、例えば持分Ｅ
Ｂ８−２６８８６号、米国特許第８５３９６６７号、特
公昭５６−８５６２５号公報等に記載されている様な孔
径が２００〜３００μｍ程度の多孔質耐火材が使用され
るが、フラックス精錬を行ったＡｌ合金溶湯のＰ遍に当
たっては、フラックス成分の一部が溶湯中へ残留混入し
これが濾過助剤的に作用してフィルターの目詰りを促進
する為、本来のフィルターメツシュの期待されるものよ
り微細な不純物の除去効果はかなり向上する。しかし塩
素ガスで精錬されたＡｌ合金溶湯では上記の様な濾過助
剤的作用を発揮する物質の混入がない為、本来のフィル
ターメツシュ以下の微細な不純物の一部がフィルターを
通過し清浄度の向上を阻害していることが明らかとなっ
た。As a result of investigating the reason why the filtration behavior differs significantly depending on the refining method as described above, the following facts were confirmed. That is, as a furnace material for filtering molten Al alloy after refining, for example,
Porous refractory materials with a pore diameter of about 200 to 300 μm are used, such as those described in No. B8-26886, U.S. Patent No. 8539667, and Japanese Patent Publication No. 56-85625, etc., but Al alloys that have undergone flux refining are used. When pouring the molten metal, some of the flux components remain in the molten metal and act like a filter aid, accelerating filter clogging. The impurity removal effect is considerably improved. However, since molten Al alloy refined with chlorine gas does not contain substances that act as filter aids as mentioned above, some of the fine impurities that are smaller than the original filter mesh pass through the filter, resulting in improved cleanliness. It has become clear that this is hindering the improvement of

こうしたところから、塩素ガスで精錬されたＡｌ合金溶
湯の濾過効率を高めようとすれば、フィルターによる濾
過工程で濾過助剤を使用することが有効であろうと考え
られた。こうした予測を基に、色々な濾過助剤を用いた
場合の不純物除去効果を調べた。その結果、−過助剤と
して従来から汎用されているシリカ及び／又はアルミナ
系、窒化物系等は濾過助剤の機能自体は十分に発揮した
が、それらの一部がフィルターを通過してＡｌ合金溶湯
中へ混入し、かえって清浄度を低下させる場合もあった
。この為濾過助剤として優れた効果を示し且つＡｌ合金
溶湯に悪影響を及ぼすことのない物質を求めて実験を行
なった結果、塩化ナトリウム及び塩化カリウムの微粉末
がＡｌ合金溶湯の濾過助剤として優れた機能を発揮し得
ることが確認された。即ち塩化ナトリウム及び（又は）
塩化カリウムよりなる微粉末を濾過助剤として使用する
と、塩素ガス精錬では除去することができず且つその後
の一般的な濾過によっても除去しきれない微細な不純物
を可及的に除去することができ、しかもこれらの塩化物
が溶湯中に混入して清浄度を低下させることは殆んどな
く、フラックス精錬後に濾過処理して得られるＡｌ合金
溶湯に比べて何ら遜色のない清浄度を得ることができる
。From this point of view, it was thought that in order to increase the filtration efficiency of molten Al alloy refined with chlorine gas, it would be effective to use a filter aid in the filtration process using a filter. Based on these predictions, we investigated the impurity removal effects when using various filter aids. As a result, although silica and/or alumina-based, nitride-based, etc., which have traditionally been widely used as filter aids, functioned well as filter aids, some of them passed through the filter and formed aluminum. In some cases, it got mixed into the molten alloy, reducing the cleanliness. For this reason, we conducted experiments to find a substance that has excellent effects as a filter aid and does not have a negative effect on molten aluminum alloys.As a result, fine powders of sodium chloride and potassium chloride were found to be excellent as filter aids for molten aluminum alloys. It was confirmed that it can perform the functions described above. i.e. sodium chloride and/or
When fine powder made of potassium chloride is used as a filter aid, it is possible to remove as much as possible the fine impurities that cannot be removed by chlorine gas refining and cannot be removed by subsequent general filtration. Moreover, these chlorides are hardly mixed into the molten metal and reduce the cleanliness, and it is possible to obtain a cleanliness that is comparable to that of the Al alloy molten metal obtained by filtration treatment after flux refining. can.

尚塩化ナトリウムや塩化カリウムの濾過助剤としての使
用態様は特に限定されないが、最も一般的なのは■上記
微粉体を不活性ガスによってＡｌ合金溶湯中へ吹き込む
方法、或は■該粉粒体をＡｌ合金溶湯上に投入し不活性
ガスによるバブリング等により撹拌して溶勘内へ分散さ
せる方法である。There are no particular restrictions on how sodium chloride or potassium chloride is used as a filter aid, but the most common methods are: (1) blowing the above-mentioned fine powder into a molten Al alloy using an inert gas; This is a method in which it is poured onto a molten alloy, stirred by bubbling with an inert gas, and dispersed into the melt.

これらの方法を実施する場合、濾過工程の初期段階では
、塩化物によるフィルターの目詰りがまだ十分進んでお
らず、清浄度が十分に上がらないこともある。この様な
場合は濾過の初期段階でＷ！湯をしばらく循環させるこ
とによりフィルターの目詰りを生じさせて詔き（所謂プ
レコート処理を施しておき）、しかる後に本格的な濾過
を行なうのがよい。また多孔質耐火材製のフィルターを
製造する最終段階から濾過処理に至るまでの適当な段階
で、上記プレコート処理に準する条件でフィルターに塩
化物の微粉体を付着させてもよく、この方法であれば、
−適時に初ける塩化物微粉体の吹込み乃至混合を省略す
ることもできる。尚上記微粉体をＡｌ合金溶湯内へ混入
させる場合における該微粉体の好適添加量は溶湯重量に
対して０．００５〜０．１＊であり、これ未満では濾過
助剤としての機能が十分に発揮されず、一方０．１９６
を超えるとフィルターが過度に目詰りを起こして濾過速
度が遅くなる傾向が現われてくる。When implementing these methods, in the initial stage of the filtration process, the filter may not be sufficiently clogged with chloride, and the cleanliness may not be sufficiently improved. In such a case, W! at the initial stage of filtration! It is a good idea to cause the filter to become clogged by circulating hot water for a while (perform a so-called pre-coat treatment), and then perform full-scale filtration. In addition, fine powder of chloride may be attached to the filter at an appropriate stage from the final stage of manufacturing a filter made of porous refractory material to the filtration treatment under conditions similar to the pre-coating treatment described above. if there is,
- It is also possible to omit the timely introduction or mixing of fine chloride powder. In addition, when the above-mentioned fine powder is mixed into the Al alloy molten metal, the preferred amount of the fine powder added is 0.005 to 0.1* based on the weight of the molten metal, and if it is less than this, the function as a filter aid is insufficient. Not demonstrated, while 0.196
If it exceeds this, the filter tends to become excessively clogged and the filtration speed tends to slow down.

本発明で使用するフィルターとしては、先に示した様な
種々の多孔質耐火材を使用することができるが、上記微
粉体の粒度構成は該多孔質耐火材の孔径に応じて最善の
濾過効率が得られる様に適宜選定するのがよい。As the filter used in the present invention, various porous refractory materials such as those shown above can be used, but the particle size structure of the fine powder is determined to achieve the best filtration efficiency depending on the pore size of the porous refractory material. It is preferable to select it appropriately so that the following can be obtained.

尚本発明では濾過助剤として、アルカリ金属塩化物中の
塩化ナトリウム及び塩化カリウムだけを選定しているが
、その理由は次の通りである。即ち塩化リチウムは塩化
ナトリウム等に比べて融点が低く、通常のＡｌ合金溶製
温度で溶融してしまう為に濾過助剤としての機能を発揮
し得ず、また塩化ルビジウム、塩化セシウム、塩化フラ
ンシウム等は極めて高価であって実用性を欠くからであ
る。In the present invention, only sodium chloride and potassium chloride among alkali metal chlorides are selected as filter aids for the following reasons. In other words, lithium chloride has a lower melting point than sodium chloride, etc., and it melts at the normal Al alloy melting temperature, so it cannot function as a filter aid, and it also cannot function as a filter aid. This is because it is extremely expensive and lacks practicality.

〔実施例〕〔Example〕

実施例１ 塩素精錬を行ったＪＩＳ　　５０５６系Ａｌ合金溶湯（
ｌｏｏＯＫｆ）に、市販の工業用塩化カリウム（平均粒
径：１００μｍ、５０１ｊ）を窒素ガスと共に吹込み、
東京高級炉材社製のチューブラ−フィルター（グレード
　ＨＢ）を用いて濾過した。この溶湯を用いて半連続鋳
造法により２００調φのビレットを製造し、Ｒ＝２５で
中実棒状に押出加工（ｎ＝１０　）　した後、該中実棒
表面の線状欠陥（溶湯中の不純物による）発生状況を調
べた。また比較の為塩化カリウムの吹込みを省略した他
は上記と同様にして中実棒表面の線状欠陥発生状況を調
べた。Example 1 JIS 5056 series Al alloy molten metal (
commercially available industrial potassium chloride (average particle size: 100 μm, 501j) was blown into the solution (looOKf) along with nitrogen gas,
It was filtered using a tubular filter (grade HB) manufactured by Tokyo Kyokuryokurozai Co., Ltd. Using this molten metal, a billet with a diameter of 200 mm was manufactured by a semi-continuous casting method, extruded into a solid rod shape at R = 25 (n = 10 mm), and linear defects on the surface of the solid rod (n = 10 mm) were formed using a semi-continuous casting method. The occurrence status (due to impurities) was investigated. For comparison, the occurrence of linear defects on the surface of the solid rod was investigated in the same manner as above, except that the injection of potassium chloride was omitted.

その結果、前者（塩化カリウム添加）については線状欠
陥が全く認められなかったが、後者（塩化カリウム無添
加）の場合は１０本の中実棒に対し１本に線状欠陥が発
生していた。尚フィルターの寿命については有意差を認
めることはできなかった。As a result, no linear defects were observed in the former case (potassium chloride added), but in the latter case (no potassium chloride added), one out of 10 solid rods had a linear defect. Ta. It should be noted that no significant difference could be observed regarding the lifespan of the filters.

実施例２ 塩化カリウムに代えて市販の工業用塩化ナトリウム（平
均粒径８０μｍ）を使用した他は実施例１と同様にして
デ過処理−半連続鋳造一中実棒押出しを行ない、表面の
線状欠陥発生状況を観察したところ、１０本の中実棒の
いずれにも線状欠陥は認められなかった。Example 2 Defiltration treatment, semi-continuous casting and solid bar extrusion were carried out in the same manner as in Example 1 except that commercially available industrial sodium chloride (average particle size 80 μm) was used in place of potassium chloride. When the occurrence of linear defects was observed, no linear defects were observed in any of the 10 solid rods.

また塩化カリウムと塩化ナトリウムを夫々半量づつ併用
して同様の実験を行ったところ、やはり線状欠陥は全く
認められなかった。When a similar experiment was conducted using half of each of potassium chloride and sodium chloride, no linear defects were observed.

〔発明の効果〕〔Effect of the invention〕

本発明は以上の様に構成されているので、塩素ガス精錬
を受けたＡｌ合金溶湯からでもフラックス精錬を受けた
ものと同等の清浄度を得ることができ、微細不純物に起
因する線状欠陥の発生を可及的に防止することができる
。Since the present invention is configured as described above, it is possible to obtain the same cleanliness even from molten Al alloy that has undergone chlorine gas refining as that of molten aluminum that has undergone flux refining, and eliminates linear defects caused by fine impurities. This can be prevented as much as possible.

Claims (1)

【特許請求の範囲】[Claims] 塩素ガスにより精錬されたＡｌ又はＡｌ合金溶湯中の不
純物を除去するに当たり、微粉状の塩化ナトリウム及び
／又は塩化カリウムを濾過助剤として濾過することを特
徴とするＡｌ又はＡｌ合金溶湯の清浄化方法。A method for cleaning molten Al or Al alloy, which comprises filtering the molten Al or Al alloy using finely powdered sodium chloride and/or potassium chloride as a filter aid when removing impurities from the molten Al or Al alloy refined with chlorine gas. .