JP3928818B2 - Induction furnace - Google Patents

Description

【０００１】
【発明の属する技術分野】
本発明は銅及び銅合金を溶解、精錬をするために用いる誘導炉に関するものである。
【０００２】
【従来の技術】
従来は銅および銅合金を溶解、精錬する場合、黒鉛ルツボを内装した誘導炉またはルツボ炉が用いられている。
最近では溶解、精錬がより簡便でかつ省力化、溶湯の品質調整が容易で、しかも作業環境が良い等の点から、
１．溶解効率の高い
２．溶解炉の保全が容易である
３．操炉が簡便で且つ省力化の計れる
４．公害問題の少ない
５．成分、温度の調整が容易に出来る
６．品質の安定度が高く均質性の高い溶湯が容易に得られる
等の諸利点を有している誘導炉の普及が急速に進んできている。特に５００ｋｇ以上の大型誘導炉は外周部に電気誘導コイルを配設し、このコイルの内側に必要ならばコイル保護用のコイルセメントにより被覆層を備えさせ、その内側に湯モレセンサー、絶縁材、断熱材等々を配設しその最内側に１層の耐火材壁（内張材）を構築して使用されている。この内張耐火壁の構築方法は一般には炉体の内側に所定の壁厚さを持たせるように設計された鋼製の内型枠（以下フォーマーと称する）を炉本体内に配設し、このフォーマーと炉本体との間隙部に乾粉状の不定形耐火物を投入した後、フォーマーの内側より振動を与えながら投入された不定形耐火物を加振充填させて施工する。この乾粉不定形耐火物の施工の良否が内張材の耐用を大きく左右し炉の寿命が決る。施工時の充填度が低く且つ充填度にバラツキが有ると異状損傷を来たしその耐用は短命に終る。この予定外の短命寿命の場合や大きな異状損傷は内張材にとどまらず、炉本体の損傷にもつながる重大事となり鋳造工場の稼動停止にもつながり大きな影響をもたらす。安定した操炉を行うためにはより確実なる施工を行うことが必要である。それには高い熟練度が必要とされる。このように施工の良否と共に長寿命化をはかり施工の省力化、工場の稼動率を高めるためこれに用いられる耐火材は特に吟味されたハイアルミナ質材，アルミナ質材，マグネシア質材，およびスピネル質材や、これらの材料に炭化けい素質材を５〜２０重量％添加された、炭化けい素質の耐火物に必要ならば無水硼酸等の焼結助材を添加した乾式不定形耐火物が使用に供されているが、炉の操業中に生成する銅の酸化物を主な成分とするノロの付着および組織内へのノロの選択的浸透により異成分組織の形成や過焼結により操業中において加熱冷却が繰り返されることにより内張材に亀裂が発生し、この亀裂部に地金が侵入し全体的には炉壁の残存厚を多く残しながらも耐用に耐えられなくなり内張材の寿命を短くしている。この間付着ノロの除去作業は高温中に行なわないと除去が困難となるため非常な高熱作業が要求される。このため炉壁保全の機会が多くなり炉操業率を低下させる。炉の保全費がかさむことや解体、施工と云う極度に作業環境の悪い３Ｋの代表的な作業をよぎなくされる。これらの諸問題を解決し安定した操炉が出来て、操業率が高くランニングコストが低く、良い環境での作業ができ、炉壁材の解体、施工と云う３Ｋ作業の頻度が少なく且つ簡便な作業となるよう強く望まれているのが現状である。
【０００３】
【発明が解決しようとする課題】
前述の如く、炉の稼働中に炉の内張材の稼働面に多く付着する銅の酸化物を主成分とするノロが付着する高熱場所でのノロ除去作業や亀裂の発生による地金差し等による突発的な損傷により炉の操業率の低下をまねき、ひいては鋳造工場の操業面にも支障をきたす。このための炉の保全費、チョコ停によるロスが非常に高くなることや炉の解体、打施工と云う代表的な３Ｋ作業の機会が多くなり操業面、炉の費用面、および３Ｋ作業面等々の多くの問題をかかえている。これらの諸問題を解決して工場の稼動率面、コスト面、および作業面の改善することの出来る誘導炉の内張用耐火物を提供することを技術的な課題とする。
【０００４】
【課題を解決するための手段】
本発明者等はこのような現状に鑑み炉が安定して操業ができ、且つ、ノロ取り等の高熱下での作業頻度を少なくし３Ｋ作業の軽減が計られ、突発的な内張材の解体、打施工作業をなくし、より高い安全、安定操業が維持できるために内張用耐火物の材料構成を溶融石英材５〜３０重量％、炭化けい素質材５〜４０重量％、Ａｌ_２Ｏ_３含有量が５５％以上のアルミナ質材３０〜９０重量％で、この３者の合量が９０％以上である耐火材料に必要ならば適宜の焼結助材を添加した乾粉状の不定形耐火物とすることにより解決の途を見い出したものである。即ち５５％以上のＡｌ_２Ｏ_３を含有するアルミナ質材により高耐食性を維持し、これに炭化けい素質材を加えて耐食性、スラグの組織内への耐浸透性を高めるとともに高熱伝導性がはかられる。尚溶融石英材の添加は全体の熱間線膨張率を小さくするとともに耐火物組織内に大きく異る低膨張性材料を複合化させることにより耐熱衝撃性を高める効率を生み出すことができるとともに、使用中は溶湯よりの受熱や大気との接触等により炭化けい素質材は一部酸化現象を生じクリストバライト等の酸化物を生成することや、溶融石英は粒の外層部より一部結晶化を生ずる。この酸化現象、結晶化現象による体積が膨張して耐火物素材が焼結による体積収縮をおこし、これにともなう亀裂の発生が抑制される等々の好成績を修めることができることにより溶損が少なく、割れ、亀裂が小さく、ノロの付着が少なくなることにより現在の諸問題を大きく改善することができて、安全且つ安定した操業が出来、チョコ停を改善した高能率な作業ができることおよび高熱下でのノロ除去作業も大巾に軽減することができる誘導炉を提供するものである。
【０００５】
（限定理由）
１．炭化けい素質材の添加量５〜４０重量％
ａ ５重量％以下ではノロの付着性、ノロの浸透性および耐食性の改善効果が小さい。
ｂ ４０重量％以上であると、導電材であるためエネルギー効率がちいさくなること、 耐食性および耐熱衝撃性の改善効果が認められないことおよび原料コストが高くな るためである。
２．溶融石英材の添加量５〜３０重量％
ａ ５重量％以下となると、溶融石英の諸特性を引き出すことができない。
ｂ ３０重量％以上となると耐熱衝撃性の面で強化にはなるが耐食性がより低下してく る。
３．Ａｌ_２Ｏ_３含有量５５％以上のアルミナ質材３０〜９０重量％
ａ Ａｌ_２Ｏ_３含有量５５％以下となると耐食性が低くなる。
ｂ ３０重量％以下の場合は耐食性が低くなる。
【０００６】
【実施例】
以下本発明の実施例について詳記する。
実施例に用いる耐火材料の化学成分値を表１に示し、基本粒度構成を表２に示す。
【０００７】
【表１】

【０００８】
【表２】

【０００９】
▲１▼一次基礎試験
Ａｌ₂Ｏ₃−ＳiＯ₂系材料および溶融石英材について、一次基礎試験の配合比率および試験結果を表３に示す。
【００１０】
【表３】

【００１１】
試験体は表１、２に示す定められた材料を用いて表３に示された
配合比率に調整して、焼結助材として無硼酸１重量％添加し、ミキサーにて乾式混合を行ない供試材とした。
成形方法としては乾式振動充填による成形を行なった。即ち振動台（振動数 １８００回／分のユーラスモーターを設置する）上に２５０×４０×６５ｍｍ鋼製枠内に１ｍｍ厚のステンレス製メタルケースを挿入した型を固定し、静圧にて５分間加振充填を行ない、この成形体を保形させるために８００℃で１０時間加熱した後、ステンレス製メタルケースより取り出して、試験体とした。
この試験体を用いて、品質特性値試験及び高周波誘導炉を用いて、側壁張り分け法での侵食試験を行なう。
品質特性値は１０００℃ １０時間過熱処理を行なった試験体で行った。
侵食試験の条件
溶解物 銅
溶湯温度 １３００℃
保持時間 ７２時間
この基礎試験の結果よりＡｌ_２Ｏ_３−ＳｉＯ_２系材料でＡｌ_２Ｏ_３５０％含有材は溶損が大きい。尚溶融石英材は稼動層の焼結が進み、溶損量はアルミナ材に比べ大きな差はなく異成分の浸透も非常に少ない状態である。
２．二次基礎試験
炭化けい素の適正添加量を求めるため二次基礎試験を行なった。
その配合比率と試験結果を表４に示す。
【００１２】
【表４】

【００１３】
一次基礎試験のＮｏ３およびＮｏ４を基として、アルミナ質材３０重量％、ムライト質材７０重量％を基準材とし、ムライト質材と炭化けい素質材を置換して、炭化けい素質材の適正配合量を求めた。
試験体は一次基礎試験と同様の方法で製出し、品質特性値試験および浸食試験を行ない検討した。
この二次基礎試験の結果より炭化けい素質材の添加量は５重量％より異成分の浸透深さおよび耐溶損、耐スラグ性の効果が認められ、添加量の増量にともない３５重量％まではその改善効果が高くなるが４０重量％以上ではほぼ同じ位の平行値で推移する。
▲３▼三次基礎試験
二次基礎試験をもとに溶融石英材の適正配合比率をきめるため三次基礎試験を行った。その結果を表５に示す。
二次基礎試験の試験材▲３▼，▲４▼を基に炭化けい素質材１５重量％，アルミナ質材３０重量％，ムライト質材５０重量％を基準材とし、ムライト質材と溶融石英材を置換して溶融石英材の適正配合比率を求めた。耐熱スポーリング試験結果を表６に示す。
試験体は一次基礎試験と同様の方法で製出し、品質特性値試験浸食試験および弾性率の変化率による耐熱スポーリング性試験を行なった。
【００１４】
【表５】

【００１５】
【表６】

【００１６】
溶融石英材の添加量は５重量％で耐スポーリング性の向上が認められるが３０重量％以上ではその効果はほぼ同様である。
▲４▼実炉使用試験
基礎試験の結果にもとづいて本発明品の実炉試験を行なった。実用結果を比較例とともに表７に示す。
【００１７】
【表７】

【００１８】
本発明品の実用実施品として三次基礎試験のＮｏ２およびＮｏ４の本発明品を用いた。比較例としてＮｏ１、Ｎｏ６を用いた。
いずれも基礎試験の製造方法と同様に焼結助材として、無水硼酸１重量％添加し、ミキサーにて乾式混合を行ない、乾式不定形材として試験材を製造し、各試験材は誘導炉本体の底部に投設し底部を築造後、フォーマーを配設し、炉本体とフォーマーとの間（所定の炉側壁ライニング厚み）にこの乾式不定形材を投入して、フォーマーの内側より打撃振動を加えながら加振充填して築造し、フォーマーごと使用、開始時の初回は低温度焼結させ、銅および銅合金の溶解、精錬の通常温度よりも１００℃高い１３５０℃で２時間保持し、高温焼結を行なった後、通常の１２５０℃で溶解、精錬作業を繰返して使用した。
実炉試験に用いた誘導炉の使用条件を下記に示す。
炉の大きさ ２Ｔ
溶解物 銅
溶湯温度 １２５０℃
【００１９】
【発明の効果】
以上の結果に示されるように現在一般に用いられている表７の実用実施例比較品Ｎｏ６のアルミナ・ムライト：炭化けい素質系のハイアルミナ−炭化けい素質材は使用中に亀裂の発生が多く、かつ溝状の異状損傷へと発達し、この溝に地金が差し込み使用に耐えられなくなるが本発明品は亀裂の発生もきわめて少なく、また小さく有害な異状損傷迄に発達することなく安全で安定して使用ができる。尚総１ｃｈ当りの損傷量比は本発明品のＮｏ２とＮｏ４は比較品Ｎｏ１に対してはそれぞれ３３％，３６％、比較品Ｎｏ６に対してはそれぞれ６３％，６７％にとどまり大巾な耐用寿命の向上が見込まれ異状損傷がごく小さくなることにより耐用寿命の向上と、操業の安定性にも絶大なる効果が修められるものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an induction furnace used for melting and refining copper and copper alloys.
[0002]
[Prior art]
Conventionally, when melting and refining copper and copper alloys, induction furnaces or crucible furnaces equipped with graphite crucibles are used.
Recently, melting and refining are easier and labor-saving, the quality adjustment of the molten metal is easy, and the working environment is good.
1. 1. High dissolution efficiency 2. Maintenance of melting furnace is easy. 3. Easy operation and labor saving. There are few pollution problems. 5. Easy adjustment of ingredients and temperature. Induction furnaces having various advantages such as easy to obtain molten metal with high quality stability and high homogeneity are rapidly spreading. In particular, a large induction furnace of 500 kg or more is provided with an electric induction coil on the outer periphery, and if necessary, a coating layer is provided with coil cement for coil protection inside the coil, and a hot water sensor, insulating material, A heat-insulating material or the like is provided, and one layer of a refractory material wall (lining material) is constructed and used on the innermost side. This lining fire wall is generally constructed by disposing a steel inner mold frame (hereinafter referred to as a former) designed to give a predetermined wall thickness inside the furnace body in the furnace body, After pouring dry powder-shaped amorphous refractory into the gap between the former and the furnace body, the loaded amorphous refractory is vibrated from the inside of the former while being vibrated and filled. The quality of the construction of the dry powder amorphous refractory greatly affects the durability of the lining material and determines the life of the furnace. If the filling level at the time of construction is low and there is a variation in the filling level, abnormal damage will occur and its durability will be short-lived. In the case of this unscheduled short-lived life or a large abnormal damage, not only the lining material, but also a serious problem that leads to damage to the furnace body, it also causes the operation of the foundry to be shut down and has a great impact. In order to perform stable operation, it is necessary to perform more reliable construction. This requires a high level of skill. In this way, in order to increase the service life as well as the quality of construction, save labor in construction, and increase the operating rate of the factory, the refractory materials used for this are particularly examined high alumina materials, alumina materials, magnesia materials, and spinel. Dry amorphous refractories with 5-20% by weight of silicon carbide added to these materials and silicon carbide refractories with sintering aids such as anhydrous boric acid added if necessary. However, it is in operation due to the formation of heterogeneous structures and oversintering due to adhesion of noro mainly composed of copper oxide generated during furnace operation and selective penetration of noro into the structure. Cracking occurs in the lining material due to repeated heating and cooling in this, and the metal enters the cracked part, and overall the remaining thickness of the furnace wall remains, but the life of the lining material cannot be withstood. Is shortened. During this time, the removal of the adhesion stick is difficult unless it is performed at a high temperature, and therefore, a very high heat operation is required. For this reason, the furnace wall maintenance opportunities increase and the furnace operation rate decreases. 3K typical work with extremely poor work environment such as high furnace maintenance costs, dismantling and construction is obstructed. These problems can be solved and a stable furnace can be operated, the operation rate is high, the running cost is low, the work can be performed in a good environment, the frequency of 3K work such as dismantling and construction of the furnace wall material is low and simple. It is the present situation that there is a strong demand for work.
[0003]
[Problems to be solved by the invention]
As mentioned above, during the operation of the furnace, the removal process in the high-temperature place where the main oxide of copper oxide that adheres a lot to the working surface of the furnace lining material adheres, and the bullion insertion due to the occurrence of cracks, etc. Sudden damage caused by this will lead to a decrease in the furnace operation rate, which in turn will hinder the operation of the foundry. For this purpose, the maintenance cost of the furnace, the loss due to the chocolate stop becomes very high, the opportunity of typical 3K work such as the dismantling of the furnace, the hammering work increases, the operation side, the cost of the furnace, the 3K work side, etc. Have many problems. It is a technical problem to provide a refractory for an induction furnace lining that can solve these various problems and improve the operating rate, cost, and work of the factory.
[0004]
[Means for Solving the Problems]
In view of such a current situation, the present inventors have been able to operate the furnace stably, reduce the frequency of work under high heat, such as cutting off, and reduce 3K work. In order to eliminate dismantling and striking work and maintain higher safety and stable operation, the material composition of the refractory for lining is 5-30% by weight of fused quartz material, 5-40% by weight of silicon carbide material, Al ₂ O _{3 If the} content is 30 to 90% by weight of alumina material with a content of 55% or more and the total amount of these three materials is 90% or more, if necessary, a dry powder-like non-adhesive material added with an appropriate sintering aid The solution was found by making it a standard refractory. In other words, high corrosion resistance is maintained by an alumina material containing 55% or more of Al ₂ O ₃ , and a silicon carbide material is added to this to improve corrosion resistance and penetration of slag into the structure and high thermal conductivity. I can be taken. The addition of fused quartz material can reduce the overall hot linear expansion coefficient and create a high thermal shock resistance efficiency by compounding low-expansion materials that differ greatly in the refractory structure. Inside, the silicon carbide material undergoes a partial oxidation phenomenon due to heat received from the molten metal, contact with the atmosphere, and the like to generate oxides such as cristobalite, and the fused quartz partially crystallizes from the outer layer of the grains. This oxidation phenomenon, the volume due to the crystallization phenomenon expands and the refractory material undergoes volume shrinkage due to sintering, and the good results such as the suppression of cracking associated with this can be corrected, resulting in less erosion damage and less cracking. The cracks are small and the adhesion of noro can greatly improve the current problems, safe and stable operation, high efficiency work with improved chocolate stop and high heat. An induction furnace capable of greatly reducing the removal operation is provided.
[0005]
(Reason for limitation)
1. Addition amount of silicon carbide material 5 to 40% by weight
a When the content is 5% by weight or less, the effect of improving adhesion of Noro, penetration of Noro and corrosion resistance is small.
b When the content is 40% by weight or more, it is a conductive material, so that energy efficiency is small, corrosion resistance and thermal shock resistance are not improved, and raw material costs are increased.
2. Addition amount of fused quartz material 5-30% by weight
a If it is 5% by weight or less, various characteristics of fused silica cannot be obtained.
b When it is 30% by weight or more, although it is strengthened in terms of thermal shock resistance, the corrosion resistance is further lowered.
3. 30 to 90% by weight of alumina material with an Al ₂ O ₃ content of 55% or more
a When the Al ₂ O ₃ content is 55% or less, the corrosion resistance is lowered.
b When it is 30% by weight or less, the corrosion resistance is low.
[0006]
【Example】
Examples of the present invention will be described in detail below.
The chemical component values of the refractory materials used in the examples are shown in Table 1, and the basic particle size constitution is shown in Table 2.
[0007]
[Table 1]

[0008]
[Table 2]

[0009]
(1) Primary basic test Table 3 shows the mixing ratio and test results of the primary basic test for the Al ₂ O ₃ —SiO ₂ -based material and the fused quartz material.
[0010]
[Table 3]

[0011]
The test specimens were adjusted to the blending ratios shown in Table 3 using the materials shown in Tables 1 and 2, and 1% by weight of boric acid free as a sintering aid was added, followed by dry mixing with a mixer. Samples were used.
As a molding method, molding by dry vibration filling was performed. In other words, a mold in which a 1 mm thick stainless steel metal case is inserted into a 250 x 40 x 65 mm steel frame is fixed on a shaking table (with a Eurus motor at a frequency of 1800 times / min), and static pressure is applied for 5 minutes. After performing vibration filling, the molded body was heated at 800 ° C. for 10 hours to retain the shape, and then taken out from a stainless steel metal case to obtain a test body.
Using this specimen, an erosion test by a side wall extending method is performed using a quality characteristic value test and a high frequency induction furnace.
The quality characteristic value was measured on a specimen subjected to overheat treatment at 1000 ° C. for 10 hours.
Conditions for erosion test Melt Copper Molten metal temperature 1300 ° C
Holding time 72 hours From the results of this basic test, the Al ₂ O ₃ —SiO ₂ based material containing 50% Al ₂ O ₃ has a large melting loss. Note that the fused quartz material has been sintered in the working layer, and the amount of erosion is not significantly different from that of the alumina material, and the penetration of different components is very small.
2. Secondary basic test A secondary basic test was conducted to determine the appropriate amount of silicon carbide added.
The blending ratios and test results are shown in Table 4.
[0012]
[Table 4]

[0013]
Based on No. 3 and No. 4 of the primary basic test, the proper blending amount of silicon carbide material by replacing 30% by weight of alumina material and 70% by weight of mullite material and replacing mullite material and silicon carbide material Asked.
Test specimens were manufactured by the same method as the primary basic test, and the quality characteristic value test and the erosion test were conducted and examined.
From the results of this secondary basic test, the amount of silicon carbide material added is 5% by weight, and the effects of penetration depth of different components and resistance to erosion and slag resistance are recognized. Up to 35% by weight as the amount added is increased. Although the improvement effect becomes high, when it is 40% by weight or more, the parallel value is almost the same.
(3) Tertiary basic test Based on the secondary basic test, a tertiary basic test was conducted to determine the proper blending ratio of the fused quartz material. The results are shown in Table 5.
Based on the secondary basic test materials (3) and (4), 15% by weight of silicon carbide material, 30% by weight of alumina material and 50% by weight of mullite material, and mullite material and fused quartz material. And the proper blending ratio of the fused quartz material was determined. The heat spalling test results are shown in Table 6.
Test specimens were produced in the same manner as the primary basic test, and subjected to a quality characteristic value test erosion test and a heat resistance spalling test based on the rate of change in elastic modulus.
[0014]
[Table 5]

[0015]
[Table 6]

[0016]
The amount of the fused quartz material added is 5% by weight, and an improvement in the spalling resistance is recognized, but the effect is almost the same when it is 30% by weight or more.
(4) An actual furnace test of the product of the present invention was performed based on the result of the basic test of the actual furnace use test. Practical results are shown in Table 7 together with comparative examples.
[0017]
[Table 7]

[0018]
No. 2 and No. 4 invention products of the tertiary basic test were used as practical implementation products of the invention products. No1 and No6 were used as comparative examples.
In each case, 1% by weight of boric anhydride is added as a sintering aid in the same way as in the basic test manufacturing method, dry mixing is performed with a mixer, and test materials are manufactured as dry amorphous materials. After placing the bottom part and building the bottom part, the former is arranged, and this dry amorphous material is introduced between the furnace body and the former (predetermined furnace side wall lining thickness), and impact vibration is applied from the inside of the former. Add and vibrate while building, use with each former, first low temperature sintering at the beginning, hold copper and copper alloy at 1350 ° C for 2 hours, 100 ° C higher than the normal temperature of melting and refining, high temperature After sintering, melting and refining operations were repeated at a normal 1250 ° C. for use.
The operating conditions of the induction furnace used in the actual furnace test are shown below.
Furnace size 2T
Melt copper temperature 1250 ° C
[0019]
【The invention's effect】
As shown in the above results, the practical example comparative product No. 6 in Table 7, which is currently used in general, is a high-alumina-silicon carbide material of alumina mullite: silicon carbide based silicon carbide-based material. In addition, it develops into a groove-like abnormal damage, and the metal is inserted into this groove and can not be used, but the product of the present invention has very few cracks, and it is safe and stable without developing until a small harmful abnormal damage. Can be used. The ratio of damage per total channel is 33% and 36% for the No. 2 and No. 4 products of the present invention, and 63% and 67% for the No. 6 comparison product, respectively. The improvement of the service life is expected and the abnormal damage is reduced, so that the improvement of the service life and the stability of the operation can be greatly improved.

Claims (1)

銅および銅合金を溶解、精錬する誘導炉に於いて炉の最内側壁部又は側壁部と底部を溶融石英材５〜３０重量％、炭化けい素質材５〜４０重量％、Ａｌ_２Ｏ_３−ＳｉＯ_２系材料でＡｌ_２Ｏ_３含有量が５５％以上のアルミナ質材３０〜９０重量％で、この３者の合量が９０重量％以上である耐火材料に適宜の焼結助材を添加して製造したことを特徴とする誘導炉。In an induction furnace for melting and refining copper and copper alloys, the innermost side wall part or the side wall part and the bottom part of the furnace are 5 to 30% by weight of fused silica material, 5 to 40% by weight of silicon carbide material, Al ₂ O ₃ − An appropriate sintering aid is added to a refractory material in which the total amount of these three members is 30 to 90% by weight with a SiO ₂ material and an Al ₂ O ₃ content of 55 to 90% by weight. An induction furnace manufactured by