JP3683374B2

JP3683374B2 - Induction furnace lining material

Info

Publication number: JP3683374B2
Application number: JP09018397A
Authority: JP
Inventors: 喜久雄有賀
Original assignee: TYK Corp
Current assignee: TYK Corp
Priority date: 1997-03-24
Filing date: 1997-03-24
Publication date: 2005-08-17
Anticipated expiration: 2017-03-24
Also published as: JPH10267553A

Description

【０００１】
【発明の属する技術分野】
本発明は銅および銅合金の溶解や精錬を行う誘導炉の誘導炉用内張り材に関するものである。
【０００２】
【従来の技術】
従来は、銅および銅合金等の金属の溶解、精錬を行う場合は主に黒鉛質のルツボを内装したルツボ炉が用いられているが最近では多量の溶解や精錬が容易にできる作業効率が良く、品質の均一性や作業性が高い上作業環境が良い等の優位性を持つ誘導炉が品質管理上、作業効率上および作業環境上の諸問題より導入され、特に大型炉が急速に普及してきている。
【０００３】
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、断熱材等を配設しその最内側に１層の耐火材壁（内張り材）を構築して使用されている。この内張り耐火壁の構築方法は小型炉では黒鉛ルツボを内装して炉本体とルツボとの間隙に乾式不定形耐火物（以下バック材と称する）を充填し施工されている。また大型炉では一般的には炉本体の内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して使用に供されている。この内張りされた底部や側壁の損傷が高いとか稼働面の汚れは炉の保全作業が多くなり炉の稼働率の低下が生じ工場全体の操業にも支障をきたし大きな影響をもたらす。このため炉の長寿命化をはかるためここに用いられる耐火物は特に吟味された耐火材を用いて製造された耐火物が使用されている。
【０００４】
現在一般にはＳｉＣ５〜２０重量％、ＳｉＯ₂２〜２０重量％、Ａｌ₂Ｏ₃６０〜９５重量％の高アルミナ−炭化珪素質耐火物に必要ならば無水硼酸等の適宜の焼結助材を添加した乾式不定形耐火物が使用されているが使用回数が進むにつれて内張り材の稼働面に操炉中に生成するスラグが徐々に付着、堆積し、特に炉底部にその傾向は高く炉底が高くなり炉有効容積が減少し時にはその減少率は容量で３０容量％にも達する。このため付着スラグ落し作業を余儀なくされている。このスラグ落し作業は付着スラグが銅の酸化物と金属銅が混在することにより高熱下でないと落しずらいことより極度な３Ｋ作業となると共に炉の稼働率も低下することとなる。このような現状下でも作業効率、省力化や大型製品の需要増等により炉容が大型化へと進みこの現象が更に増大し、ますますその作業は過酷の度を増し更に保全作業頻度を多くしている。
【０００５】
これらの諸問題を解決し安定した操炉ができて操業率が高く、ランニングコストが低く、良い環境下での作業を目指すため炉の内張り材の補修や解体、新規施工と云う３Ｋ作業の頻度が少なく且つ簡便で快適な作業となることが強く望まれているのが現状である。
【０００６】
【発明が解決しようとする課題】
本発明者等はこのような現状に鑑み高温下でのスラグ落し作業と云う悪環境下での３Ｋ作業の軽減ができ、炉が正常で操炉ができ能力を十分発揮出来得る状態が維持でき、効率良く生産することが可能な誘導炉の内張り方法とその耐火物を提供することを技術的な課題とする。
【０００７】
【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、高熱下で炉の上部より覗きこむような状態で行なわれる３Ｋ作業であるスラグ等の付着物の除去作業をより軽減にでき、炉が正常で安定した操業ができ炉本来の能力を十分発揮でき得る状態が維持できる方策を見い出すためにスラグ等の付着物の付着、堆積の過程を種々の角度より調整を行った。その結果は以下の順序で進行している。
【０００８】
▲１▼操炉中に生成するスラグは出湯時に上部より下部へ、さらに炉底部へと付着して行く。
▲２▼繰返し繰返しされるため付着したスラグの成分が内張り材の組織中に浸入して表層に異質層（以下変質層と称する）を形成する。
▲３▼変質層はスラグとのなじみが良く付着し易すくなり付着度が増し堆積して行く、特に炉底部の内張り材の稼働面は湯温がやや低いため付着度合が高くなる。
▲４▼付着物とスラグ等となじみが良いので繰り返し層状付着が進む。この付着物は銅の酸化物を主成分とし、更には金属銅と混在することとなり冷却すると展性の高い性状を有してくる。
▲５▼付着したスラグの除去作業は高熱下で行うが、より厚い堆積状況となった場合は炉を冷却させて行う。
【０００９】
このようにスラグの付着はまづスラグが内張り材の組織内へ浸入し稼働層に変質層が形成される。この生成された変質層はスラグや金属銅等とのなじみが良く容易に付着現象が発生し、付着速度が早くなる。以後ほぼ同質のスラグが毎回接する。この両者はなじみ易く、この現象は繰返して層状堆積へと継がって行く、この付着堆積物中には銅の酸化物を主体とし金属銅が混在するため冷却させると銅の特性である展性が働き除去作業は非常に困難となり手間がかかる過酷な作業となるため除去が容易である高熱下での除去作業となり代表的な高熱下での３Ｋ作業がしいられる。
【００１０】
このような作業を続けるうちにも付着、堆積が進み炉容量が少なくなると共に溶解効率も大きく低下し電気エネルギーの浪費、生産性の低下により、ついには炉内張り材の取替えを余儀なくされ、その頻度が高くなっている等の現状を知見し得た。
【００１１】
以上の如くスラグの付着、堆積は操業上、生産効率上大きな問題を生じている。現在最も多く一般に用いられている耐火物の成分組成はＳｉＯ₂１５重量％、ＳｉＣ１５重量％、Ａｌ₂Ｏ₃７０重量％の乾式不定形耐火物である。この耐火物により炉の底部および側壁部共に施工されている。本発明者等は使用耐火材の特性を検討してさらに研究試験を重ねた結果、高シリカ−高炭化珪素質材とすることによりスラグの浸透、付着を大きく改善することを見い出し、炉の内張り材の材料構成を、炭化珪素質材２５〜５５重量％，ムライト質材１０〜５５重量％，溶融石英質材５〜３５重量％，天然珪石質材１０〜３０重量％を含みこの４者の合量を９０重量％以上で構成され、必要ならば無水硼酸等の焼結助剤を添加した乾式不定形耐火物とすることにより材質面で大きな改善を見い出すことができ、この乾式不定形耐火物を用いて炉の底部の厚みで３０ｍｍ以上で底部厚みの５０％迄を施工することにより現在の問題点を解決することができ正常で安全な操業を行うことのできうる方法をここに提供するものである。
【００１２】
（限定理由）
▲１▼炭化珪素質材２５〜５５重量％
２５重量％以下ではスラグの耐浸入性や対付着効果が少ない。
５５重量％以下では５５重量％を越えてもその効果が大きく改善されることもなく材料コストが高くなる。
▲２▼ムライト質材１０〜５５重量％
炭化珪素質材と混在材質となることにより組織の強化がはかられ、物性的にも秀ぐれた特性を出すが１０重量％以下ではその効果が少なく５５重量％以上となると緻密度が低下してスラグの浸透や表層での付着度が高くなる傾向を示す。
▲３▼溶融石英質材５〜３５重量％
溶融石英質材は耐熱スポーリング性と焼結力を高める効果があるが５重量％以下では効率が小さく３５重量％を越えると耐食性が劣化する。
▲４▼天然珪石質材１０〜３０重量％
天然珪石質材は熱間での残存膨張性を高める。耐火材の使用中の受熱による焼結収縮を改善し、亀裂の発生を防止するが１０重量％以下では効果が少なく、３０重量％を越えると使用中内張り材の組織の脆弱化が進むためである。 ▲５▼炭化珪素材、ムライト質材、溶融石英質材、および天然珪石質材の合量が９０％重量以上この４者の合量が９０重量％以下となると本発明による内張り材の特質がそこなわれるためである。
▲６▼炉の底部に本発明による内張り材を厚み３０ｍｍ以上で底部厚みの５０％迄の厚さに施工する。炉底部材の厚みが３０ｍｍ以下であると炉底部材の溶損が進むと一部浮きあがり現象を含めて損傷が大きくなる。又炉底部厚みの５０％以上の厚みまでは損傷には至らないためである。
【００１３】
【実施例】
実施例に用いた原料の化学成分値を表１に示す。
【表１】

実施例材の粒度構成値を表２に示す。
【表２】

実施例に用いた本発明材と比較例としての一般材の配合比率を表３に示す。
【表３】

【００１４】
本発明の実施例を以下に説明する。
本発明の試験体は表１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で表２に示される粒度構成に調整して、焼結助剤として無水硼酸１重量％添加し、ミキサーにて乾式混合を行ない供試材とした。
【００１５】
成形方法として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の鋼製枠内に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。
この試験結果を表４に示す。
【表４】

【００１６】
本発明の実用実施例には表３に示された本発明の実施例材を表３▲１▼の材質に比較材は表３▲２▼の材質にそれぞれ無水硼酸を１重量％添加し、ミキサーにて乾式混合を行いそれぞれ乾式不定形耐火物を製造して用いる。
【００１７】
まず炉底の最低部に厚みの５０％の厚みを比較材の表３▲２▼で打設した後、その上部に本発明材表３▲１▼を残りの５０％厚みに打設し、この上に鋼製のフォーマーを配設し炉本体とフォーマーとの間（所定の炉側壁厚み）に比較材である現用品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側壁部と加振充填して築造し、スターティングブロックを入れフォーマー共に通電し加熱させながら徐々に昇温し低温域での焼結硬化をさせながら通常溶解時の温度より１０００℃高い１３５０℃迄昇温し２時間保持し高温焼結を初回使用時にのみ行った後は正規の溶解温度１２５０℃に調整し出湯する通常の使用とする。
【００１８】
尚本発明実用実施例として内張り用耐火物の構成を図１に示す。
【００１９】
実用実施例に用いた誘導炉の使用条件を下に記す。
炉の大きさ１０Ｔ炉
溶解材銅
溶湯温度１２５０℃
【表５】

【００２０】
【発明の効果】
表５に示されるように実用試験の結果では比較例に比べ本発明の態様（内張り材のライニング法）では底部でのスラグの付着開始時がおそく、かつ付着量が少ないことより付着したスラグの除去作業も比較例と比べほぼ同じ使用回数時では５回が３回と少なくなり、炉の冷却回数も３回と少なくなったことより炉の加熱、冷却頻度の減少により炉壁の亀裂の発生発達が軽減し、地差しによる炉の寿命終了もなく良好なる効果が得れらた。今回の試験結果では本発明の耐火物および内張り材の構成であれば更に耐用寿命の延長が見込まれる。尚本発明の一番の課題であるスラグ付着の軽減と炉壁材の損傷を小さくし安全な操業、３Ｋ作業の改善については付着したスラグの除去作業、補修作業の頻度減少により１ｃｈ当りの作業頻度数が０．０３４１ｃｈ／回が０．０１３４ｃｈ／回となりその頻度比率は１００％が４１．３％となり、更に耐用寿命が１５４ｃｈが１９８ｃｈとなり１２８％の耐用向上につながって溶損効率の改善となり、生産コストの引き下げにも大きな貢献をすることができ、その効果が絶大なるものである。
【図面の簡単な説明】
【図１】本発明の誘導炉用内張り材の実施態様を示す断面図である。
【図２】本発明の誘導炉用内張り材の他の実施態様を示す断面図である。
【図３】従来の誘導炉用内張り材の実施態様を示す断面図である。
【符号の説明】
１従来の乾式不定形耐火物
２本発明による不定形耐火物
３側壁部用乾式不定形耐火物[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an induction furnace lining material for induction furnaces for melting and refining copper and copper alloys.
[0002]
[Prior art]
Conventionally, when melting and refining metals such as copper and copper alloys, a crucible furnace equipped with a graphite crucible has been mainly used. Recently, however, a large amount of melting and refining is easy and work efficiency is high. Induction furnaces with superior quality uniformity, workability and good work environment have been introduced due to quality control, work efficiency and work environment problems, especially large furnaces have been rapidly spreading. ing.
[0003]
In the induction furnace, an electric induction coil is arranged on the outer periphery, and if necessary, a coating layer is provided with coil cement for protecting the coil inside the coil, and a hot water sensor, insulating material, heat insulating material, etc. are arranged inside the coil. It is installed and constructed with a refractory material wall (lining material) on the innermost side. In the construction method of the lining refractory wall, in a small furnace, a graphite crucible is provided and a gap between the furnace main body and the crucible is filled with a dry amorphous refractory (hereinafter referred to as a back material). In a large furnace, generally, a steel inner mold (hereinafter referred to as a former) designed to have a predetermined wall thickness is disposed in the furnace body. After throwing dry powder-shaped amorphous refractory into the gap with the furnace body, it is used for use by oscillating and filling the loaded amorphous refractory while applying vibration from the inside of the former . The damage to the bottom and side walls, which are lined up, and the contamination of the operation surface, increase the maintenance work of the furnace, lower the operation rate of the furnace, hinder the operation of the whole factory and have a great influence. For this reason, in order to prolong the life of the furnace, the refractory used here is a refractory manufactured using a refractory material examined in particular.
[0004]
Now commonly SiC5~20 wt%, SiO ₂ 2 to 20 wt%, Al ₂ O ₃ 60~95% by weight of high alumina - an appropriate sintering aids of boric anhydride, if necessary in the silicon carbide refractories The added dry amorphous refractory is used, but as the number of uses increases, the slag generated during the operation of the lining material gradually adheres and accumulates on the operating surface of the lining material. It becomes higher and the effective volume of the furnace decreases, and sometimes the reduction rate reaches 30% by volume. For this reason, adhesion slag dropping work is forced. This slag dropping operation is an extreme 3K operation because the adhering slag is difficult to drop unless it is under high heat due to a mixture of copper oxide and metallic copper, and the operating rate of the furnace is also reduced. Even under such circumstances, the furnace capacity has increased due to work efficiency, labor savings, and increased demand for large products, and this phenomenon has further increased. The work has become more severe and more frequent. doing.
[0005]
The frequency of 3K work such as repairing and dismantling of furnace lining materials and new construction in order to solve these problems and achieve stable operation, high operation rate, low running cost, and work in good environment At present, there is a strong demand for a simple and comfortable work with a small amount of work.
[0006]
[Problems to be solved by the invention]
In view of such a current situation, the present inventors can reduce 3K work in a bad environment such as slag dropping work at high temperature, maintain a state in which the furnace is normal, the furnace can be operated, and the capacity can be fully exhibited. It is a technical problem to provide a method for lining an induction furnace and its refractory that can be efficiently produced.
[0007]
[Means for Solving the Problems]
In view of the current situation, the present inventors can further reduce the removal work of deposits such as slag, which is a 3K work performed in a state of looking into the top of the furnace under high heat, and the furnace is normal and stable. In order to find a measure that can maintain the state that can be fully operated and can fully demonstrate the original capacity of the furnace, the process of depositing and depositing slag and other deposits was adjusted from various angles. The results are in the following order:
[0008]
(1) Slag generated during the operation of the furnace adheres from the upper part to the lower part and further to the furnace bottom part when the hot water is discharged.
{Circle around (2)} Since it is repeated repeatedly, the adhering slag component penetrates into the structure of the lining material and forms a heterogeneous layer (hereinafter referred to as an altered layer) on the surface layer.
(3) The altered layer has a good fit with the slag, becomes easy to adhere and increases in the degree of adhesion, and accumulates.
{Circle around (4)} Since the adhesion with the deposit and slag is good, the layered adhesion repeatedly proceeds. This deposit is composed mainly of a copper oxide and further mixed with metallic copper, and has a highly malleable property when cooled.
(5) The work to remove the adhering slag is performed under high heat, but if the deposition becomes thicker, the furnace is cooled.
[0009]
In this way, the slag adheres first, and the slag penetrates into the structure of the lining material, and an altered layer is formed in the working layer. The generated deteriorated layer is well-suited to slag, metallic copper, etc., and the adhesion phenomenon easily occurs, and the adhesion speed increases. Since then, slag of almost the same quality will contact each time. Both of these are easy to adapt, and this phenomenon is repeatedly transferred to layered deposition. The adhesion deposit is mainly composed of copper oxide and contains metallic copper. However, since the removal work becomes very difficult and laborious, the removal work is performed under high heat which is easy to remove, and typical 3K work under high heat is performed.
[0010]
As the work continues, adhesion and deposition progress, the furnace capacity decreases, melting efficiency also decreases greatly, waste of electrical energy, and productivity drop, eventually requiring replacement of the furnace liner. I was able to find out the current situation such as
[0011]
As described above, the adhesion and accumulation of slag cause a big problem in operation and production efficiency. Component composition of the refractory used in the currently most commonly SiO ₂ 15 wt%, SiC15 wt%, Al ₂ O ₃ 70 wt% of the dry monolithic refractory. Both the bottom and side walls of the furnace are constructed by this refractory. As a result of investigating the characteristics of the refractory material used and conducting further research tests, the present inventors have found that the use of a high silica-high silicon carbide material greatly improves the penetration and adhesion of slag, and the lining of the furnace The material composition includes 25 to 55% by weight of silicon carbide material, 10 to 55% by weight of mullite material, 5 to 35% by weight of fused silica material, and 10 to 30% by weight of natural siliceous material. It is possible to find a great improvement in terms of material by using a dry amorphous refractory with a total amount of 90% by weight or more and adding a sintering aid such as boric anhydride if necessary. We provide a method that can solve the current problems by constructing up to 50% of the thickness of the bottom of the furnace with a thickness of 30 mm or more using an object. To do.
[0012]
(Reason for limitation)
(1) Silicon carbide material 25-55% by weight
If it is 25% by weight or less, the penetration resistance and anti-adhesion effect of the slag are small.
If it is 55% by weight or less, even if it exceeds 55% by weight, the effect is not greatly improved, and the material cost is increased.
(2) Mullite material 10-55% by weight
Strengthening of the structure can be achieved by using silicon carbide and mixed materials, and excellent physical properties can be obtained. However, the effect is less at 10% by weight or less, and the density decreases at 55% by weight or more. The tendency of slag penetration and surface adhesion is high.
(3) Fused quartz material 5 to 35% by weight
The fused quartz material has the effect of enhancing the heat spalling resistance and sintering power, but the efficiency is small at 5% by weight or less, and the corrosion resistance deteriorates when it exceeds 35% by weight.
(4) 10-30% by weight of natural siliceous material
Natural siliceous material enhances the residual expansibility in the hot. Sintering shrinkage due to heat reception during use of refractory material is improved and cracking is prevented, but the effect is less at 10% by weight or less, and when it exceeds 30% by weight, the structure of the lining material in use becomes more brittle. is there. (5) The characteristics of the lining material according to the present invention when the total amount of silicon carbide material, mullite material, fused quartz material, and natural siliceous material is 90% by weight or more and the total amount of these four members is 90% by weight or less. This is because there is a failure.
(6) The lining material according to the present invention is applied to the bottom of the furnace to a thickness of 30 mm or more and up to 50% of the thickness of the bottom. When the thickness of the furnace bottom member is 30 mm or less, the damage including the partially floating phenomenon increases as the melting of the furnace bottom member proceeds. Moreover, it is because damage is not caused to the thickness of 50% or more of the furnace bottom thickness.
[0013]
【Example】
Table 1 shows the chemical component values of the raw materials used in the examples.
[Table 1]

Table 2 shows the particle size composition values of the example materials.
[Table 2]

Table 3 shows the blending ratios of the present invention material used in the examples and the general material as a comparative example.
[Table 3]

[0014]
Examples of the present invention will be described below.
The specimen of the present invention was adjusted to the particle size composition shown in Table 2 at the blending ratio shown in Table 3 using the specified materials shown in Table 1, and 1% by weight of boric anhydride was added as a sintering aid. Then, dry mixing was performed with a mixer to obtain a test material.
[0015]
As a molding method, molding by dry vibration filling was performed. That is, a mold in which a 1 mm thick stainless steel metal case is inserted into a 250 × 40 × 65 mm steel frame is fixed on a vibration table (installing a Eurus motor with a frequency of 1800 times / minute), and 5 by static pressure. After shaking and filling for minutes, 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.
The test results are shown in Table 4.
[Table 4]

[0016]
In the practical examples of the present invention, the materials of the examples of the present invention shown in Table 3 were added to the materials shown in Table 3 (1), and the comparative materials were added to the materials shown in Table 3 (2) by 1% by weight of boric anhydride. Dry-mixing is performed with a mixer to produce dry-type amorphous refractories.
[0017]
First, 50% of the thickness was cast in the lowest part of the furnace bottom according to Table 3 (2) of the comparative material, and then the present invention material table (3) (1) was cast on the upper part to the remaining 50%. On top of this, a steel former is placed, and the dry-type indeterminate material of the current product, which is a comparative material, is inserted between the furnace body and the former (predetermined furnace side wall thickness) while applying impact vibration from the inside of the former. It is built by exciting and filling the side wall, and a starting block is inserted. The former is energized and heated, and the temperature is gradually raised while heating and hardening in a low temperature range up to 1000 ° C., which is 1000 ° C. higher than the normal melting temperature. After the temperature is raised and held for 2 hours and high-temperature sintering is performed only at the first use, the normal melting temperature is adjusted to 1250 ° C. and the hot water is discharged.
[0018]
In addition, the structure of the refractory material for lining as a practical example of this invention is shown in FIG.
[0019]
The operating conditions of the induction furnace used in the practical examples are described below.
Furnace size 10T furnace melting material Copper melt temperature 1250 ° C
[Table 5]

[0020]
【The invention's effect】
As shown in Table 5, in the results of the practical test, in the aspect of the present invention (lining material lining method) compared to the comparative example, the start of slag adhesion at the bottom is slow, and the amount of adhering slag is less. In comparison with the comparative example, the number of times of removal is almost the same as the number of times of use, 5 times is reduced to 3 times, and the number of cooling times of the furnace is reduced to 3 times. The development was reduced, and a good effect was obtained without ending the life of the furnace due to the ground. In this test result, the service life is expected to be further extended if the refractory and the lining material of the present invention are configured. The most important issue of the present invention is the reduction of slag adhesion and the safe operation by reducing damage to the furnace wall material. The improvement of 3K work is achieved by reducing the frequency of removal of slag and repair work. The frequency number is 0.0341 ch / time is 0.0134 ch / time, and the frequency ratio is 100% to 41.3%, and the service life is 154 ch to 198 ch. It can also make a significant contribution to lowering production costs, and the effect is enormous.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an embodiment of an induction furnace lining material according to the present invention.
FIG. 2 is a cross-sectional view showing another embodiment of the induction furnace lining material of the present invention.
FIG. 3 is a cross-sectional view showing an embodiment of a conventional lining material for an induction furnace.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Conventional dry-type refractory 2 Unshaped refractory according to the present invention 3 Dry-type refractory for side walls

Claims

Silicon carbide material 25-55 wt%, mullite material 10-55 wt%, fused quartz material 5-35 wt%, natural siliceous material 10-30 wt%, the total amount of these four is over 90 wt% If necessary for the refractory material composed of the above, the working layer at the bottom of the furnace is constructed with an amorphous refractory with an appropriate sintering aid added to a thickness of 30 mm or more and up to 50% of the bottom thickness, and other parts are generally used. A lining material for an induction furnace, characterized in that it has a bottom multi-layer structure constructed by using a dry amorphous refractory material of alumina-mullite-silicon carbide.