JP4198439B2 - Consumable carbon anode for smelting titanium metal - Google Patents

Description

【００４６】
【表２】

【００４７】
次に、上記で得られた各試料片について、CO₂酸化消耗速度、CO₂全酸化消耗量（あわせて「CO₂酸化消耗試験」とする）の測定を以下のようにして行った。
先ず、試験装置内の上皿天秤に試料片を載せ、この試験装置内が窒素ガス雰囲気になるようにして９８０℃に保持した後、ガスを切替えCO₂ガス１.７５リットル/minを送入した。その後、試料片の重量減量分が6.0ｇになったところで、送入するガスを再びCO₂ガスから窒素ガスに切替え、窒素ガス雰囲気中で冷却した。そして、取り出した各試料片に衝撃を加え、ルーズカーボンを強制的に脱落させ、脱落カーボン量及び残りのカーボン量、更に試験装置内に自然に脱落したカーボン量を秤量し、次式によってCO₂酸化消耗速度とCO₂全酸化消耗量を求めた。結果を表２に示す。
CO₂酸化消耗速度(g/hr)＝ ガス化量／反応時間
CO₂全酸化消耗量(%)＝ 100 + (強制脱落量+自然脱落量)／ガス化量×100
ガス化量＝ 試験前試料片重量 − (強制脱落量 + 自然脱落量+残留量)
【００４８】
また、上記で得られた各試料片を陽極として４Ｎ−ＮａＯＨ水溶液を電解液とする水溶液電気分解による電解消耗試験を以下のようにして行った。
先ず、各試料片の中央部にネジ加工をして真鍮製導電棒をネジ止めして陽極とした。この陽極を、予めSUS製円筒管を陰極として内部に固定した1000mlビーカーに取り付け、高さを調整して固定した。その後、ビーカー内に４Ｎ−ＮａＯＨ水溶液を試料片の一定の高さになるまで注ぎ、０.５Ａ／ｃｍ²の直流電流を通じて電気分解を行った。総電流量が２００Ａに達したところで電流を止め、上記陽極を真鍮製導電棒から取り外して水洗した後、乾燥させて秤量した。また、脱落カーボンを含んでいる電解液はフィルターで濾過し、脱落カーボンを乾燥して秤量し、次式によって全消耗速度と選択酸化度を求めた。得られた結果を表２に示す。尚、理論ガス化量は、上記電気分解における通電量からガス化反応する量を理論的な計算により求めたものである。
全消耗速度(g/A hr)＝(理論ガス化量+脱落カーボン量)/総電流量×(経過時間)
選択酸化度(%)＝ 脱落カーボン量/理論ガス化量 × 100
【００４９】
上記結果を示した表２から分かるように、電極材としての基本特性試験、CO₂酸化消耗試験及び電解試験については試料番号３〜７の場合に好ましい結果であることが分かった。尚、表２中の嵩比重、電気比抵抗、曲げ強度についてはｎ＝６の平均値であり、CO₂酸化消耗試験及び電解試験についてはｎ＝２の平均値で示してある。
【００５０】
次に、表１に示す粒度分布に調整したか焼温度１３００℃の石炭系コークスを用い、脱灰処理した石炭系ピッチからなるバインダーピッチと混捏して、温度１５０℃、圧力２００kgfで１分間型込成形したブロックを形成し、９８０℃で焼成した後、内径１２０mmφ、高さ２００mm（内寸）のルツボ型炭素陽極試料を作製し、塩化カルシウム（CaCl₂）と酸化カルシウム（CaO）からなる無機溶融塩の電気分解を行って電流値の経時測定を行った。
上記ルツボ壁にはSUS製丸棒を接続して後に陽極として通電できるように加工しておき、このルツボはSiC抵抗体を組んだ電気炉に置いて乾燥した。その後、予め配合したCaCl₂＋２mol%CaOからなる混合塩をこのルツボ内に入れ、Arガスを通じながら９００℃まで昇温した。昇温の途中で、混合塩の溶解に伴う体積減少を見計らって順次混合塩を追加し、最終的に３.５kgの混合溶融塩を作成した。全量溶解後、ルツボ中央の位置にSUS陰極を配置・固定して溶融塩に入れ、炭素陽極とSUS陰極との間に２.８Vの定電圧を印加して電気分解を行った。約４時間後、電気分解を停止し、SUS陰極を電解浴の上部まで引き上げてから電気炉の電源を止め、Ar雰囲気中で溶融塩、ルツボ型炭素陽極、SUS陰極を冷却した。一例として、試料番号５及び試料番号９の電流値測定結果を図１のグラフに示す。
【００５１】
上記電気分解での電流値の経時測定では、電気分解の開始と共にルツボ型炭素陽極の表面から炭酸ガスの気泡が発生し、電流が流れ始めた。この電流を流している媒体として酸素イオン等が考えられ、時間の経過と共に酸素イオンが炭酸ガスとして消費されて系外に出されることで、定電圧下では電流値が低下していく。しかし、図１に示したように試料番号９では電気分解開始１５０分を経過したあたりから、電流値は上昇した。これは、ルツボ型炭素陽極とSUS陰極との間にルツボ型炭素陽極から発生した浮遊炭素が顕著に堆積し、両電極が短絡して迂回電流が発生したためと考えられる。この電流値が上昇する傾向は、試料番号１、２、８〜１１で顕著であり、試料番号３〜７ではこの上昇傾向が小さく抑えられた。
【００５２】
この試験例１より、骨材コークスの粒度分布を制御することで、骨材コークス粒子の充填密度の制御が可能となり、一次焼成炭素材を消耗性炭素陽極とする場合でも、強度特性、電気的特性、酸化消耗の均一性などの熱間反応安定性に優れ、さらに電気分解中の遊離炭素を低減することができることが分かる。
【００５３】
〔試験例２〕
骨材コークスのか焼温度の違いによって、炭素陽極の基本特性試験、CO₂酸化消耗試験、電解試験の結果に与える影響について調べるため、以下のような測定を行った。
表３に示すようにか焼温度を変えた骨材コークスの試料を用意した（試料番号１２〜１７）。この骨材コークスは、上記試験例１の結果より、粒子径０.０７４mm以下が１８重量％、粒子径３.０mm以上が３０重量％である粒度分布を有し、上記試験例１と同様な試料片を作製した。尚、試料番号１７については、参考例とするためにか焼温度１３００℃の骨材コークスを用いて９８０℃で一次焼成したものを、更に２５００℃で二次焼成して得たグラファイト成形材からなる試料片とした。
上記試料片について、上記試験例１と同様の方法により基本特性試験、CO₂酸化消耗試験及び電解試験を行った。その結果を表４に示す。
【００５４】
【表３】

【００５５】
【表４】

【００５６】
上記表４に示した結果より、か焼温度が低い骨材コークスを使用して得た試料片の選択酸化度が小さく、特に、か焼温度が１２００℃以下の試料片（試料番号１４〜１６）では、比較例とするためにグラファイト成形材から得た試料片（試料番号１７）に近い値となった。
【００５７】
この試験例２より、骨材コークスのか焼温度を制御することで、バインダーコークスの選択酸化による骨材コークスの脱落現象を防止し、遊離炭素量を低減可能であることが分かる。
【００５８】
〔試験例３〕
骨材コークスの材質の違いから形成した炭素陽極を用いて金属チタンの製錬を行った場合に、得られる金属チタンへの汚染による影響を調べるために、以下のような試験を行った。
先ず、か焼温度がそれぞれ１０００℃である石油系コークス、石炭系コークス及び脱灰処理した石炭系コークスであって、それぞれ、粒子径０.０７４mm以下が１８重量％、粒子径３.０mm以上が３０重量％の粒度分布を有する試料を用意し（試料番号１８〜２０）、脱灰処理した石炭系ピッチからなるバインダーピッチと混捏した後ブロックを形成し、９８０℃で焼成した後、内径φ１２０mm、高さ２００mm（内寸）のルツボ型炭素陽極を作製した。また、か焼温度１３００℃の骨材コークスを用いて９８０℃で一次焼成したものを、更に２５００℃で二次焼成して得たグラファイト成形材を用いて上記と同様なルツボ型炭素陽極についても用意した（試料番号２１）。
【００５９】
このルツボ型炭素陽極の壁にはSUS製丸棒を接続し、後に陽極として通電できるように加工した。このルツボ型炭素陽極は、SiC抵抗体を組んだ電気炉に配置して乾燥した後、予め配合したCaCl₂＋２mol%CaOからなる混合塩をこのルツボ内に入れ、Arガスを通じながら９００℃まで昇温した。昇温の途中で、混合塩の溶解に伴う体積減少を見計らって順次混合塩を追加し、最終的に３.５kgの混合溶融塩を調製した。全量溶解後、SUS製陰極を溶融塩に入れ、１.０Ｖの定電圧を印加して、水分及び初期に溶融塩中に存在する不純物である鉄（Fe）、バナジウム（V）、及び硫黄（S）のうち予め除去が可能なものを除去するための予備電解を実施した。
【００６０】
予備電解実施後、SUS製陰極を引き出し、ルツボ内に溶融塩電気分解用のチタン製陰極を挿入した。このチタン製陰極は、チタンネットを内径８mmφ、高さ１４０mmの円筒状に丸めて底部を８mmφチタン丸棒で封じ、チタンネット容器としたもので、更に、この内部に酸化チタン４gを入れて上部を同じく８mmφチタン丸棒で蓋をし、電気分解用電源へ接続できるように加工したものである。ルツボ中央の位置で、かつ酸化チタンが全て溶融塩に浸漬する深さにチタン陰極を配置・固定し、炭素陽極とチタン陰極との間に２.８Ｖの定電圧を印加して、溶融塩の電気分解を行った。約４時間経過した後、電気分解を停止し、チタン陰極を電解浴の上部まで引き上げてから電気炉の電源を止め、Ar雰囲気中でチタン陰極及び溶融塩を冷却した。
【００６１】
室温まで除冷した後、チタン陰極を電気炉から引き上げ氷水で水洗して内部のチタン（投入時は酸化チタン）を回収した。回収したチタンは温調デシケーター中で乾燥した後、蛍光Ｘ線分析及び赤外吸収法により分析した。これらの分析結果から、回収されたチタンは全量金属チタンに還元されていることが分かった。上記の内容を各試料から得た炭素陽極について実施し、それぞれ回収された金属チタンに含まれる不純物の濃度について表５に示す。
【００６２】
【表５】

【００６３】
上記表５より、鉄、硫黄、バナジウムの濃度については、石油系コークスを骨材コークスとした場合が最も高く、次いで、石炭系コークス、脱灰処理した石炭系コークス、グラファイト成形材の順であった。一方、金属チタン中の炭素濃度については、グラファイト成形材とその他の骨材コークスの値はほぼ同等であった。
【００６４】
この試験例３より、骨材コークスの材質を石炭系コークス、脱灰処理した石炭系コークスとすることで、より安価な一次焼成炭素材であっても二次焼成を行うグラファイト成形材と同程度に溶融塩中への不純物の移行を低減することができ、高純度な金属チタンが製造できることが分かる。
【００６５】
〔試験例４〕
電気分解によって、炭素陽極から発生する気体が溶融塩中を浮上する際の気体の浮上領域を制限するために、以下のような試験を行った。
視覚的に理解しやすくするため、水モデルによる電気分解を実施した場合の様子を写真にした図２及び３で説明する。反応槽である電解槽に見立てて、幅８５０mm×奥行８５０mm×高さ１０００mmのアクリル板製の水槽１に水を入れたものを用意し、この水槽内には消耗性炭素陽極に見立てた中空鉄板２であって、この中空鉄板２の側面２aにフィルター３を貼り合せたものが浸漬されている。この中空鉄板２の上面２bの中央から、実際の溶融塩の電気分解で発生すると考えられるガス量を計算して圧縮エアーを吹き込み、上記側面２aに貼り合せたフィルター３から気体が噴出され、中空鉄板２の側面２aを上昇する気体の様子を観察した。図２では、中空鉄板２の側面２aが、鉛直方向に対して角度０度の場合であり、図３はこの側面２aを鉛直方向に対して角度１２度でオーバーハング状に傾斜した案内傾斜面とした場合を示している。図２、３から明らかなように、オーバーハング状に傾斜を付した場合の方が、水面１aに浮上する気泡浮上領域の幅（Ｌ）を小さく制限できることが分かる。
【００６６】
この試験例４より、炭素陽極の側面にオーバーハング状に傾斜した案内傾斜面を設けることで、この炭素陽極で発生する気体の浮上領域を制御することが可能であることが分かる。
【００６７】
〔試験例５〕
図４に示した消耗性炭素陽極８を用いて、図５のような金属チタン製錬装置４による金属チタンの製錬を行った。
マグネシアルツボ５に酸化カルシウムを含有する塩化カルシウムの混合塩を入れ、９００℃で保持して混合溶融塩６とし、予め、脱水・不純物除去のための予備電解を実施した。次いで、マグネシアルツボ５の底面に対し５度傾斜するようにチタンプレート製の陰極板７を配置し、この陰極板７の上方には、か焼温度１０００℃であって粒子径０.０７４mm以下が１８重量％、粒子径３.０mm以上が３０重量％の粒度分布を有する石炭系骨材コークスと、脱灰処理した石炭系ピッチからなるバインダーピッチとを混捏して、９８０℃で焼成して得た消耗性炭素陽極８を配置した（試料番号２２）。この消耗性炭素陽極８は、混合溶融塩６に浸漬する消耗性炭素陽極の底面８aが鉛直方向に対して８５度の角度で傾斜するように加工してあり、この底面８aは上記陰極板７と平行に相対面すると共にこの底面８aと陰極板７との間の距離Ｘは３０ｍｍとなるようにした。また、上記消耗性炭素陽極８には、チタン導電棒９が取り付けられて、図示外の直流電源のプラス端子と接続されており、また、陰極板７の端部にはチタン導電棒１０が取り付けられて、図示外の直流電源のマイナス端子と接続されている。尚、上記陰極板７以外で混合溶融塩６に浸漬している部分については、マグネシア保護管１１で被ってある。
【００６８】
このような状況の下、上記陰極板７上に１０ｇの酸化チタン１２を沈めて、両電極間に２０Ａの電流を流して定電流による電気分解を行った。この電気分解において、消耗性炭素陽極８の底面８aで発生する炭酸ガス（CO₂）等の気体は、この底面８aに付された傾斜によって一定方向に案内されて上昇するため、この底面８aが案内傾斜面として働き、気体の浮上領域を制限した。
【００６９】
また、図６に示した消耗性炭素陽極１７を用いて、図７のような金属チタン製錬装置１３による金属チタンの製錬を行った。
マグネシアルツボ１４に酸化カルシウムを含有する塩化カルシウムの混合塩を入れ、９００℃で保持して混合溶融塩１５とし、予め、脱水・不純物除去のための予備電解を実施した。次いで、この混合溶融塩１５には、鉛直方向に対して１５度の傾斜を有した金属チタンプレート製の陰極板１６を配置し、また、か焼温度１０００℃であって粒子径０.０７４mm以下が１８重量％、粒子径３.０mm以上が３０重量％の粒度分布を有する石炭系骨材コークスと脱灰処理した石炭系ピッチからなるバインダーピッチとを混捏して、９８０℃で焼成して得た消耗性炭素陽極１７を配置した（試料番号２３）。この消耗性炭素陽極１７は、混合溶融塩１６に浸漬するその側面１７aが鉛直方向に対して１５度の角度でオーバーハング状に傾斜するように加工してあり、この側面１７aは上記陰極板１６と平行に相対面すると共にこの側面１７aと陰極板１６との間の距離Ｙが２５ｍｍとなるようにした。また、マグネシアルツボ１４の内壁面と上記陰極板１６との間になる位置に、チタン製のネットで作製した箱型容器１８を配置して混合溶融塩１５に浸漬するようにした。上記消耗性炭素陽極１７には、チタン導電棒１９が取り付けられており、図示外の直流電源のプラス端子と接続され、また、陰極板１６の端部にはチタン導電棒２０が取り付けられて、図示外の直流電源のマイナス端子と接続されている。
【００７０】
このような状況の下、上記箱型容器１８に１０ｇの酸化チタン２１を入れ、両電極間に２０Ａの電流を流して定電流による電気分解を行った。この電気分解において、消耗性炭素陽極１７の側面１７aで発生する炭酸ガス（CO₂）等の気体は、この底面１７aに付された傾斜によって一定方向に案内されて上昇するため、この底面１７aが案内傾斜面として働き、気体の浮上領域を制限した。
【００７１】
尚、上記試料番号２２と試料番号２２における両電極間の距離の差（５mm）は、試料番号２２では、炭素陽極と陰極との間に酸化チタンを沈めているため、この酸化チタンの初期の厚み（５mm）を考慮したものである。また、上記金属チタン製錬装置１３において、陰極板を鉛直方向に対して平行に配置すると共に炭素陽極の側面が鉛直方向に対して平行とした案内傾斜面を有さない消耗性炭素陽極（試料番号２４）の場合について、その他の条件を上記と同様にして電気分解を行った。
【００７２】
この試験例５において、上記酸化チタンが効率１００％で全量金属チタンに還元されるのに必要な理論電気量の１.５倍の電気量をそれぞれ流したところで電気分解を終了し、消耗性炭素陽極を引き出してアルゴン雰囲気下で室温まで冷却した。また、沈めた酸化チタンについては、マグネシアルツボごと水洗及び希塩酸で洗浄した後、粉末の状態で回収した。回収した物質は温調デシケーター中で乾燥した後、Ｘ線回折分析、蛍光Ｘ線分析及び赤外吸収法により分析を行った。それぞれの分析結果を表６に示す。
【００７３】
【表６】

【００７４】
消耗性炭素陽極が案内傾斜面を有する試料番号２２及び２３では、回収した物質の全量が金属チタンに還元されていることが分かった。一方、消耗性炭素陽極が案内傾斜面を有さない試料番号２４では、金属チタン以外に金属チタンが炭素によって汚染されたことを示すチタンカーバイド（TiC）が混在することが分かり、得られた金属チタンの品質が不十分であった。
【００７５】
【発明の効果】
本発明によれば、二次焼成を行ったグラファイト成形材と比較して安価である骨材コークスの一次焼成炭素材で形成された炭素陽極を金属チタン製錬の消耗性炭素陽極に用いることで工業的に有利に金属チタンを製造することができ、得られる金属チタンについても汚染されることがなく、二次焼成を行ったグラファイト成形材を消耗性炭素陽極とした場合と比べて品質面でも遜色がない。
【図面の簡単な説明】
【図１】 図１は、無機溶融塩中の電気分解における電流値の経時変化を示すグラフである。
【図２】 図２は、電気分解中の消耗性炭素陽極から発生する気体の様子を表すためのモデルであって、消耗性炭素陽極に見立てた中空鉄板を水槽に沈めて圧縮ガスを送り込んだ様子の写真である（炭素陽極の側面が傾斜していない場合）。
【図３】 図３は、電気分解中の消耗性炭素陽極から発生する気体の様子を表すためのモデルであって、消耗性炭素陽極に見立てた中空鉄板を水槽に沈めて圧縮ガスを送り込んだ様子の写真である（炭素陽極の側面が傾斜している場合）。
【図４】 図４は、本発明の試験例５に係る消耗性炭素陽極を示す斜視説明図である。
【図５】 図５は、本発明の試験例５に係る金属チタン製錬装置を示す断面説明図である。
【図６】 図６は、本発明の試験例５に係る別の消耗性炭素陽極を示す斜視説明図である。
【図７】 図７は、本発明の試験例５に係る別の金属チタン製錬装置を示す断面説明図である。
【符号説明】
１…水槽、１a・・・水面、２…中空鉄板、２a…中空鉄板の側面、２b…中空鉄板の上面、３…フィルター、４、１３…金属チタン製錬装置、５、１４…マグネシアルツボ、６、１５…混合溶融塩、７、１６…陰極板、８…消耗性炭素陽極、８a…消耗性炭素陽極の底面、９、１０、１９、２０…チタン導電棒、１１…マグネシア保護管、１２、２１…酸化チタン、１７…消耗性炭素陽極、１７a…消耗性炭素陽極の側面、１８…箱型容器。[0001]
BACKGROUND OF THE INVENTION
In the present invention, titanium oxide (TiO 2) is obtained by electrolysis using an inorganic molten salt as an electrolytic bath. ₂ The present invention relates to a consumable carbon anode for metal titanium smelting that can be industrially advantageously mass-produced by reducing metal) to metal titanium (Ti).
[0002]
[Prior art]
[Patent Document 1]
WO99 / 64638 pamphlet
[Non-Patent Document 1]
Sei Takeuchi and Osamu Watanabe, The Japan Institute of Metals, 1964, 28, 9, 549-554
[0003]
Titanium metal has been revealed for its excellent properties one after another, and in recent years it has been used not only in the field of aerospace, but also in the field of consumer products such as cameras, glasses, watches and golf clubs. Furthermore, the demand is expected also in the field of building materials and automobiles. And about the manufacturing method of this metal titanium, the method currently industrially used is only what is called a crawl method except the electrolytic method which refines titanium on a very small scale in order to manufacture high purity titanium for semiconductors. It has become.
[0004]
However, in the smelting of titanium metal by such a crawl method, although titanium oxide is used as a raw material for production, the production process is long because the titanium oxide is reduced to titanium tetrachloride having a low boiling point. In addition, vacuum separation under high temperature and reduced pressure is indispensable in the production process of sponge-like titanium metal. Further, since the produced sponge-like metal titanium is obtained as one large lump, when producing a product titanium ingot, Crushing and crushing of this sponge-like metal titanium is indispensable. Moreover, since the concentration of dissolved oxygen in the sponge-like metal titanium differs greatly between its center and outer skin, depending on the application of the product titanium ingot, In the pulverization process, the material from the center and the material from the outer skin must be separated. It has become the cost of production on to the big factors that extremely high.
[0005]
Therefore, in the past, several metal titanium smelting methods have been proposed in place of the crawl method, reflecting the increasing demand for metal titanium. Typically, electrolysis of inorganic molten salt is carried out in the reaction vessel. A method is known in which a bath is formed and titanium oxide is reduced to titanium metal using an electrolysis method.
[0006]
For example, Sakae Takeuchi and Osamu Watanabe, The Japan Institute of Metals, Vol. 28 (1964) No. 9, pp. 549-554, a graphite crucible is used as the anode and a molybdenum electrode is used as the cathode in the center. As an inorganic molten salt that forms an electrolytic bath, calcium chloride (CaCl ₂ ), Calcium oxide (CaO) and titanium oxide (TiO ₂ The mixed molten salt at 900 to 1100 ° C. is added, and titanium oxide is electrolyzed in an electrolytic bath in an atmosphere of argon (Ar) as an inert gas. ⁴⁺ ) Is deposited on the surface of a molybdenum electrode to produce titanium metal.
[0007]
Further, WO 99/64638 uses a titanium crucible as a reaction vessel, and calcium chloride (CaCl) as an inorganic molten salt forming an electrolytic bath in the crucible. ₂ In this electrolytic bath, a graphite electrode is disposed as an anode and a titanium oxide electrode is disposed as a cathode. Between the graphite electrode and the titanium oxide electrode in the electrolytic bath, A voltage is applied to the cathode to form oxygen ions (O ^2- ), And the extracted oxygen ions are converted into carbon dioxide (CO ₂ ) And / or oxygen gas (O ₂ ) To reduce the titanium oxide electrode itself and convert it to titanium metal.
[0008]
Furthermore, in the present inventors, titanium oxide (TiO ₂ ) Smelting method of titanium metal to produce titanium metal (Ti), which is calcium chloride (CaCl ₂ ) And calcium oxide (CaO) and / or mixed molten salt composed of calcium (Ca), and an electrolytic bath for electrolyzing calcium oxide and / or calcium chloride in the mixed molten salt and oxidation It is divided into a reduction zone for reducing titanium, and in the above electrolysis zone, calcium oxide and / or calcium chloride in the mixed molten salt is electrolyzed and calcium (Ca) and monovalent calcium ions (Ca) which are reductive decomposition products. ⁺ In the reduction zone, the titanium oxide introduced into the reduction zone is reduced by the calcium and monovalent calcium ions generated in the electrolysis zone, and the sponge metal obtained by reduction of the titanium oxide. A titanium metal smelting method and smelting apparatus that deoxygenate titanium (Ti) has been proposed (Japanese Patent Application No. 2002-210,537).
[0009]
The common point in the above three methods is that oxygen ions (O) dissolved in the inorganic molten salt are electrolyzed in the inorganic molten salt. ^2- ) Is captured by the carbon anode, and the carbon anode and oxygen ions (O ^2- ) And the carbon anode itself is oxidized and consumed, so that oxygen ions (O ^2- ) Carbon dioxide (CO ₂ ), Carbon monoxide gas (CO), oxygen gas (O ₂ ) To be discharged out of the system as a mixed gas consisting of all or part of the above. Therefore, the carbon anode used in these methods is generally called a consumable carbon anode.
[0010]
However, in metal titanium smelting using a consumable carbon anode, there is a problem caused by the consumable carbon anode. For example, in the method described in Takeuchi / Watanabe's paper, oxygen ions (O ^2- ) And the graphite crucible that is the anode ₂ ) And carbon monoxide gas (CO), and the titanium metal deposited on the molybdenum electrode surrounded by the graphite crucible is continuously exposed to these carbon dioxide gases and the like. Carbon dioxide or the like generates carbon by reaction with calcium (Ca) contained in the molten salt, and the deposited titanium metal is exposed to this carbon. When the deposited metal titanium comes into contact with carbon dioxide gas or the like or carbon, it immediately becomes titanium carbide or titanium oxide due to good reactivity at high temperature, or causes solid solution carbon or solid solution oxygen of metal titanium.
Such a problem can also occur in the method described in WO 99/64638 and the method proposed by the present inventors. That is, when carbon dioxide gas generated on the surface of the consumable carbon anode comes into contact with the reduced metal titanium in the molten salt, it immediately reacts with titanium carbide, titanium oxide, solid solution carbon, solid solution due to good reactivity at high temperatures. There exists a possibility of producing dissolved oxygen and deteriorating the quality of the metal titanium obtained. Furthermore, the generated carbon is suspended in the molten salt so that it is in physical contact with the reduced metallic titanium, causing contamination of the metallic titanium with carbon, and in some cases, these carbons are melted. There is also a risk of floating in the salt and hindering the operation of titanium metal smelting.
[0011]
On the other hand, when the consumable carbon anode contains ash such as iron, sulfur, vanadium as impurities, these impurities migrate into the inorganic molten salt due to the reaction and consumption of the consumable carbon anode, and as a result In addition, when titanium oxide is reduced in the vicinity of the cathode, there is a problem that these impurities are taken into the metal titanium and the quality of the obtained metal titanium is deteriorated.
[0012]
For this reason, as a countermeasure against impurities, a consumable carbon anode that is actually used is generally a graphite molding material that has been subjected to secondary firing. In order to obtain the graphite molded material that has been subjected to the secondary firing, first, a material in which a binder pitch enters the voids formed between the aggregate coke grains and the aggregate coke is bonded is primarily fired at about 1300 to 1400 ° C. To produce a primary calcined carbon material. In this primary calcined carbon material, the binder pitch is calcined to be coked to become binder coke. Next, the primary calcined carbon material is further calcined at a high temperature of 2400 ° C. or higher to graphitize the aggregate coke and the binder coke, thereby obtaining the above graphite molding material. Since this graphite molding is fired at a high temperature, the aggregate coke and binder coke are fired at almost the same temperature to exhibit relatively uniform characteristics, and the ash contained in the aggregate coke and binder coke is gas. Therefore, even when used as a consumable carbon anode, the migration of contaminants into the inorganic molten salt can be suppressed.
[0013]
However, for this secondary firing, since the primary firing carbon material needs to be further fired, the number of steps for processing increases, and a large amount of thermal energy for high temperature firing is required. Compared to the manufacturing cost. Therefore, when metal titanium smelting is carried out industrially, there is a problem in terms of cost with respect to the use of the graphite molding material subjected to such secondary firing as a consumable.
[0014]
[Problems to be solved by the invention]
Therefore, the present inventors reduced the cost in the smelting of metallic titanium by forming an electrolytic bath of an inorganic molten salt in the reaction tank and reducing the titanium oxide using an electrolysis method to produce metallic titanium. As a result of earnest study on consumable carbon anodes for metal titanium smelting that can mass-produce titanium metal in an industrially advantageous manner, it was found that the primary calcined carbon material of aggregate coke with limited particle size distribution, calcination temperature, and material By forming a carbon anode, even when a primary calcined carbon material that is advantageous in terms of cost is used, the contamination of the resulting titanium metal by carbon and other impurities is reduced, and the quality of the resulting titanium metal is lowered. It has also been found that operational problems in metal smelting can be avoided. In addition, the inventors have found that the shape of the carbon anode can be limited to the floating region of the gas generated at the carbon anode, so that contamination of the deposited titanium metal can be prevented as much as possible, and the present invention has been completed.
[0015]
Accordingly, an object of the present invention is to provide a consumable carbon anode for metal titanium smelting that can smelt metal titanium advantageously industrially.
Another object of the present invention is to provide a consumable carbon anode for metal titanium smelting that does not contaminate metal titanium due to impurities, free carbon, etc. generated from the consumable carbon anode. .
[0016]
[Means for Solving the Problems]
That is, the present invention is a consumable carbon anode for metal titanium smelting used in the smelting of metal titanium in which an electrolytic bath of an inorganic molten salt is formed in a reaction vessel and titanium oxide is reduced using an electrolysis method. And the carbon anode has a particle size distribution in which a particle size of 0.074 mm or less is 15 wt% or more and 25 wt% or less and a particle size of 3.0 mm or more is 22 wt% or more and 37 wt% or less. A consumable carbon anode for smelting titanium metal, characterized in that it is formed of a calcined carbon material.
[0018]
Furthermore, the present invention provides a consumable carbon anode for metal titanium smelting used in the smelting of metal titanium in which an electrolytic bath of an inorganic molten salt is formed in a reaction vessel and titanium oxide is reduced using an electrolysis method. The carbon anode has a guide slope inclined in an overhanging manner at an angle of 1 to 45 degrees with respect to the vertical direction on the side face facing at least parallel to the cathode used in electrolysis and immersed in the inorganic molten salt. It is a consumable carbon anode for smelting of titanium metal, characterized in that it has a surface and guides the gas generated from the carbon anode and rising by the guide inclined surface along the inclined guide surface.
[0019]
Furthermore, the present invention provides a consumable carbon anode for metal titanium smelting used in the smelting of metal titanium in which an electrolytic bath of an inorganic molten salt is formed in a reaction tank and titanium oxide is reduced using an electrolysis method. The carbon anode has a guide inclined surface at an angle of 80 to 90 degrees with respect to the vertical direction on the bottom surface that is at least parallel to the cathode used in electrolysis and immersed in the inorganic molten salt. A consumable carbon anode for smelting of titanium metal, characterized in that the gas generated from the carbon anode and rising by the guide inclined surface is guided along the guide inclined surface.
[0020]
In the present invention, for metal titanium smelting using the consumable carbon anode of the present invention, an electrolytic bath of an inorganic molten salt is formed in a reaction tank, and titanium oxide is reduced to metal titanium using an electrolysis method. The method is not particularly limited as long as the metal titanium is smelted to produce metal titanium, and as a specific example, the method proposed by the present inventors in the previous application (Japanese Patent Application) No. 2002-210537).
[0021]
In the present invention, the consumable carbon anode for metal titanium smelting used in the smelting of titanium metal has a particle size of 0.074 mm or less of 15 wt% or more and 25 wt% or less, and a particle size of 3.0 mm or more is 22 wt%. % To 37% by weight, preferably an aggregate having a particle size distribution in which a particle size of 0.074 mm or less is 17% to 22% by weight and a particle size of 3.0 mm or more is 25% to 35% by weight. A consumable carbon anode made of coke primary calcined carbon material is preferred. Controlling the particle size distribution of the aggregate coke affects the filling characteristics of the powder, and thus directly relates to the performance of the obtained primary calcined carbon material, such as bulk specific gravity, strength, electrical characteristics, and thermal characteristics. That is, by setting the particle size distribution of the aggregate coke in the above range, the bulk specific gravity of the obtained primary calcined carbon material is increased, and the bending strength as a consumable carbon anode is improved. When used as a consumable carbon anode, it is advantageous in terms of strength performance as a structure and electrical performance as an electrode.
[0022]
In addition, when the particle size distribution of the aggregate coke is within the above range, the selective oxidation degree indicating the ratio when the aggregate coke and the binder coke are consumed by electrolysis decreases, and excellent performance is exhibited. .
[0023]
This electrolytic test selective oxidation degree is calculated by calculating the consumption weight of the consumable carbon anode due to the generation of carbon dioxide from the amount of electricity used for the actual electrolysis after performing electrolysis of water in an aqueous solution added with caustic soda (NaOH). The amount of dropout from the consumable carbon anode is calculated by comparing the weight with the actual weight after drying, and the degree of selective oxidation is measured. Although there is a difference in temperature between hot and cold compared to electrolysis in molten salt, both tend to match in that the carbon of the electrically consumable carbon anode is consumed by electrolysis. Therefore, it is possible to compare test results in the same aqueous solution system. If the degree of selective oxidation is small, it means that the oxidation reaction of the carbon anode is uniformly performed during the electrolysis of the molten salt. If the degree of selective oxidation is large, the aggregate coke and binder coke are consumed by electrolysis. This means that the binder coke is preferentially oxidized and consumed. When this selective consumption oxidation occurs, the unconsumed carbon portion that is not consumed gradually becomes loosely bonded to other carbon anode portions, and eventually falls off to become free carbon or floating carbon. Therefore, by exhibiting excellent performance with a small degree of selective oxidation, binder coke is not selectively oxidized and consumed, so that generation of free carbon and floating carbon due to dropping of aggregate coke can be prevented. It is possible to prevent as much as possible the contamination of the titanium metal produced by carbon.
[0024]
Further, when the particle size distribution of the aggregate coke is in the above range as in the present invention, CO indicating the degree of carbon oxidation by carbon dioxide gas. ₂ Oxidation consumption rate and CO ₂ Excellent performance with low oxidation total consumption. This CO ₂ Oxidation consumption rate and CO ₂ By exhibiting excellent performance with a small amount of total oxidation consumption, there is a low possibility that the carbon anode surface will be oxidized and consumed again when the carbon dioxide gas generated in the electrolysis on the carbon anode surface rises along the surface. This is advantageous. This is advantageous in terms of reducing the carbon contamination of the titanium metal due to secondary free carbon and the like, and reducing the cost of the carbon anode.
[0025]
Therefore, in the present invention, regarding the particle size distribution of the aggregate coke, the particle size distribution in which the particle size of 0.074 mm or less is 15 wt% or more and 25 wt% or less and the particle diameter of 3.0 mm or more is 22 wt% or more and 37 wt% or less. When a consumable carbon anode formed of primary calcined carbon material with an aggregate of coke is used as a consumable carbon anode for metal titanium smelting, free carbon generated in the molten salt due to electrolysis of inorganic molten salt and floating Generation | occurrence | production of carbon can be suppressed as much as possible, and contamination by carbon of the metal titanium obtained can be prevented. Moreover, the problem that free carbon etc. short-circuit between a carbon anode and a cathode and obstruct | occlude the operation of metal titanium smelting can be avoided. For the above range, an aggregate coke having a particle size distribution in which a particle size of 0.074 mm or less is 17 wt% or more and 22 wt% or less and a particle size of 3.0 mm or more is 25 wt% or more and 35 wt% or less, Selective oxidation degree, bulk specific gravity, bending strength, electrical resistivity, CO of the primary calcined carbon material obtained without being affected by the calcining temperature of the aggregate coke described below ₂ Oxidation consumption rate and CO ₂ It can be excellent in performance such as total consumption of oxidation, and when used as a consumable carbon anode for metal titanium smelting, the resulting titanium metal reduces contamination by free carbon as much as possible. Thus, titanium metal can be produced industrially advantageously.
[0026]
Moreover, the calcination temperature of the aggregate coke in the present invention is 800 ° C. or more and 1200 ° C. or less, preferably 950 ° C. or more and 1100 ° C. or less. If the calcining temperature of the aggregate coke increases, the bulk specific gravity and bending strength increase, on the contrary, the electrical resistivity, CO ₂ Oxidation consumption rate, CO ₂ The total oxidation consumption is reduced. This is thought to be because the aggregate coke becomes denser and its properties change by changing the calcining temperature of the aggregate coke. Even if the aggregate coke has the same particle size distribution, the primary calcined carbon material This is considered to be due to the change in the overall characteristics of the film. Further, if the calcining temperature of the aggregate coke is lowered, the difference in oxidation resistance between the aggregate coke and the binder coke is reduced, so that the selective oxidation degree of the electrolytic test is small and excellent performance is exhibited. In the consumable carbon anode formed from the primary calcined carbon material of such an aggregate coke, as described above, the binder coke is not selectively oxidized, so that the aggregate coke can be prevented from falling off. Further, contamination of titanium metal with free carbon or the like can be reduced as much as possible.
[0027]
Therefore, if the calcining temperature of the aggregate coke is lower than 800 ° C, the consumable carbon anode formed from the primary calcined carbon material of this aggregate coke is insufficient in terms of strength, and conversely the calcining temperature is higher than 1200 ° C. If it is high, the degree of selective oxidation becomes too large, and the amount of free carbon and floating carbon generated in the molten salt increases, which causes a problem of contamination of the resulting titanium metal. If the calcining temperature of the aggregate coke is not less than 950 ° C. and not more than 1100 ° C., the degree of selective oxidation, bulk specific gravity, bending strength, and electrical resistivity of the obtained primary calcined carbon material are not affected by the particle size distribution of the aggregate coke. , CO ₂ Oxidation consumption rate and CO ₂ It can be excellent in performance such as total consumption of oxidation, and when used as a consumable carbon anode for metal titanium smelting, the metal titanium obtained should reduce contamination by free carbon as much as possible. Thus, titanium metal can be produced industrially advantageously. As for the calcination temperature, the closer to the firing temperature in the primary firing step, the closer the properties of the aggregate coke and the properties of the binder coke after the primary firing, the overall quality becomes uniform, and the above performance is excellent respectively. This is more advantageous in that
[0028]
Further, the aggregate coke in the present invention is preferably coal-based coke. Petroleum coke, which is widely used in general industry, contains components such as iron, sulfur, and vanadium because it uses petroleum as a raw material, but coal-based coke has fewer of these components than petroleum-based coke, and aggregate. In the consumable carbon anode of the present invention formed from primary calcined carbon material of coke, the aggregate coke may be coal-based coke.
[0029]
The coal-based coke is preferably deashed. The deashing process is, for example, a method for producing coke in which impurities are removed at the pitch stage using an organic solvent extraction method or the like that dissolves pitch in an organic solvent to remove or concentrate the impurity element. If there is, the method is not particularly limited, but specifically, the refinement process has been advanced until the impurity content in the coal-based coke obtained as a product is 50 ppm or less of iron, 100 ppm or less of silicon, and 20 ppm or less of zinc. It is good. In the case of coal-based coke that has been deashed, the impurity components can be further reduced as compared with coal-based coke that is not subjected to deashing treatment. Compared to the conventional method, the required amount of thermal energy is remarkably small, so that an increase in the manufacturing cost of the consumable carbon anode can be suppressed.
[0030]
In the present invention, the primary calcined carbon material may be a primary calcined carbon material obtained by using a deashed pitch as a binder pitch. As such a binder pitch, specifically, using the organic solvent extraction method described above, etc., the product pitch has been refined to an impurity content of 50 ppm or less, silicon 100 ppm or less, and zinc 20 ppm or less. It is good to be. The primary calcined carbon material obtained using such a binder pitch can reduce impurities contained, and if it is a consumable carbon anode for metal titanium smelting, it can prevent contamination of the resulting metal titanium. it can.
[0031]
About the consumable carbon anode in the present invention, when it is used for the smelting of metallic titanium by forming it with the primary calcined carbon material of the aggregate coke obtained by combining the control of the particle size distribution and the control of the calcination temperature. Thus, the effect of reducing the contamination of titanium metal obtained is improved. In addition, such aggregate coke is coal-based coke, and further, this coal-based coke is deashed, and the primary calcined carbon material binder is obtained using a deashed pitch. By combining this, it is possible to further improve the effect of reducing the contamination of titanium metal in the smelting of the above titanium metal, even if it is a consumable carbon anode formed of a primary calcined carbon material advantageous in cost, Titanium metal can be produced industrially advantageously without deteriorating the quality of the metal titanium obtained.
[0032]
Regarding the shape of the consumable carbon anode used for titanium metal smelting in the present invention, this consumable carbon anode is perpendicular to at least the side face parallel to the cathode used for electrolysis and immersed in the inorganic molten salt. It has a guide inclined surface inclined in an overhang shape at an angle of 1 to 45 degrees, preferably 5 to 30 degrees, and the gas generated from the carbon anode by the guide inclined surface rises along the guide inclined surface. It is good to guide you. For example, when the cathode in the electrolytic bath is disposed in the longitudinal direction of the electrolytic bath, the consumable carbon anode in the present invention faces the side parallel to the cathode and the side has the above angle. It should be a guide slope.
[0033]
As described above, in the electrolysis of the inorganic molten salt, a gas such as carbon dioxide gas is generated on the surface of the consumable carbon anode. This gas such as carbon dioxide gas does not have a force in the direction perpendicular to the surface of the carbon anode in the early stage of generation, but only a vertical force that attempts to float due to the difference in specific gravity from the molten salt. is there. Therefore, by raising the gas along the surface of the consumable carbon anode, the gas such as carbon dioxide gas generated on the surface of the carbon anode material rises along the guide inclined surface inclined in the overhang shape, and the gas Can be limited. As a result, gas such as carbon dioxide gas can be discharged out of the system without unnecessarily diffusing in the molten salt, so that contamination of the deposited titanium metal can be prevented as much as possible. The gas generated on the surface of the carbon anode spreads in a bloom shape due to gas-liquid friction, liquid viscosity, convection, and other forces when it floats in the molten salt, so the inclination angle that inclines into this overhang is large. However, if the tilt angle exceeds 45 degrees, the volume effect of the gas always exists as a region where the gas floats, and the tilt effect is not recognized. The shape of the consumable carbon anode in the present invention is not particularly limited except that it has the guide inclined surface, and may be a flat plate shape, a conical shape, a quadrangular pyramid shape, or the like. .
[0034]
Further, with respect to the guide inclined surface of the consumable carbon anode, for example, a part of the inorganic molten salt forming the electrolytic bath is electrolyzed to generate a reductive decomposition product, and the generated reductive decomposition product causes titanium oxide to be generated. Metal titanium smelting to produce metal titanium by thermal reduction of the inorganic molten salt, calcium chloride (CaCl ₂ ) And calcium oxide (CaO) and / or calcium (Ca), and an electrolytic bath formed by the mixed molten salt is used in the mixed molten salt by the cathode used for the electrolysis. And / or an electrolysis zone for electrolyzing calcium chloride, calcium (Ca) and monovalent calcium ions (Ca generated in the electrolysis zone) ⁺ ) To produce titanium metal by dividing into a reduction zone for reducing titanium oxide, the consumable carbon anode in the present invention faces at least parallel to the cathode in the electrolysis zone and is in the mixed molten salt. On the side surface to be immersed, there is a guide inclined surface inclined in an overhang shape at an angle of 1 to 45 degrees, preferably 5 to 30 degrees with respect to the vertical direction, and the guide inclined surface generates and rises from the carbon anode. The gas is preferably guided along the guide inclined surface.
[0035]
Regarding the reaction in the electrolytic bath in the above electrolysis, titanium oxide (TiO 2 in the electrolytic bath) ₂ ) Is calcium (Ca) and monovalent calcium ion (Ca ⁺ ), And the resulting solid metal titanium (Ti) precipitates as a heterogeneous phase. In addition, calcium oxide (CaO) produced by the reaction is dissolved in the mixed molten salt as it is, and the activity is lowered and the driving force of the reaction is increased.
TiO ₂ + 2Ca ⁺ + 2e = Ti + 2Ca ²⁺ + 2O ^2- ...... (1)
[O] _Ti + Ca ⁺ + E = Ca ²⁺ + O ^2- ……………… (2)
Ca ⁺ , E, Ca ²⁺ , And O ^2- Represents ions and electrons present in the mixed molten salt, respectively [O] _Ti Indicates solid solution oxygen in the produced titanium metal. Formula (1) shows a reduction reaction of titanium oxide, and Formula (2) shows a deoxidation reaction in which solid solution oxygen in the metal titanium that proceeds continuously after the formation of metal titanium in Formula (1) is deoxygenated. Show.
[0036]
The calcium oxide (CaO) generated above reduces the divalent calcium of the calcium oxide to monovalent at the cathode to generate monovalent Ca ions. In addition, oxygen ions (O ^2- ) Moves to the carbon anode side, and this oxygen ion (O ^2- ) Reacts with the captured carbon anode, CO ₂ -CO gas is generated.
Anode: C + O ^2- = CO + 2e …………………………… (3)
C + 2O ^2- = CO ₂ + 4e ………………………… (4)
Cathode: Ca ²⁺ + E = Ca ⁺ ………………………………… (Five)
[0037]
Thus, oxygen ions (O ^2- In the reaction surface of the carbon anode that captured), carbon dioxide gas is generated as described above. This carbon dioxide gas causes contamination of the deposited titanium metal as described above. In the above example, The physical contact with calcium (Ca), which is a reducing substance of titanium oxide, causes a reaction unrelated to the reduction, consumes substances such as calcium, and reduces the current efficiency of electrolysis, and the above reduction Carbon or the like generated from a reaction unrelated to the short circuit between the carbon anode and the cathode causes a problem of inhibiting the operation of titanium metal smelting itself. Therefore, by making the side surface of the consumable carbon anode into the guide inclined surface having the above-mentioned inclination angle, the generated carbon dioxide gas or the like is restricted to a specific region, and the carbon dioxide gas or the like is floated in the molten salt. Unnecessary diffusion can be prevented and contact with titanium metal can be limited.
[0038]
Further, the carbon anode in the present invention is at least an angle of 80 to 90 degrees, preferably 80 to 85 degrees with respect to the vertical direction on the bottom surface which is parallel to at least the cathode used in electrolysis and immersed in the inorganic molten salt. It is also possible to guide the gas generated from the carbon anode and rising along the guide inclined surface. For example, when the cathode in the electrolytic bath is disposed in a position (parallel to the electrolytic bath) that is substantially parallel to the bottom surface of the reaction vessel, the consumable carbon anode in the present invention is parallel to the cathode on the bottom surface. It is preferable that the bottom face is a guide inclined face having the above-mentioned angle.
[0039]
When the consumable carbon anode and the cathode are arranged in the above-described positional relationship in the electrolytic bath, the consumable carbon anode is positioned above the cathode, so that oxygen ions (O ^2- ) Floats and is captured at the bottom surface of the carbon anode. As described above, gas such as carbon dioxide gas is generated on the bottom surface of the carbon anode, but if the bottom surface of the carbon anode is a guide inclined surface having the above angle, the gas rises along the guide inclined surface, By limiting the gas floating region, carbon dioxide and the like can be removed out of the system without unnecessarily diffusing in the molten salt. The shape of the consumable carbon anode in the present invention is not particularly limited except that it has the guide inclined surface, and may be a flat plate shape, a conical shape, a quadrangular pyramid shape, or the like. .
[0040]
Further, on the guide inclined surface of the consumable carbon anode, a part of the inorganic molten salt forming the electrolytic bath is electrolyzed to produce a reductive decomposition product, and the generated reductive decomposition product heats titanium oxide. Metal titanium smelting to produce metal titanium by reduction, wherein the inorganic molten salt is calcium chloride (CaCl ₂ ) And calcium oxide (CaO) and / or calcium (Ca), and in the mixed molten salt, a cathode positioned substantially parallel to the bottom of the reaction vessel and a position above the cathode And an electrolysis of calcium oxide and / or calcium chloride in the mixed molten salt between the electrodes, and calcium (Ca) and monovalent calcium ions ( Ca ⁺ In the case of metal titanium smelting in which titanium oxide is reduced by reducing titanium oxide according to the present invention, the consumable carbon anode in the present invention is perpendicular to at least the bottom surface facing in parallel with the cathode and immersed in the mixed molten salt. It has a guide inclined surface having an angle of 80 to 90 degrees, preferably 80 to 85 degrees with respect to the direction, and the rising gas generated from the carbon anode is guided along the guide inclined surface by the guide inclined surface. Good.
[0041]
As described above, when the consumable carbon anode and the cathode are arranged one above the other in the electrolytic bath, and titanium oxide is located between these two electrodes to smelt metal titanium, the reduction produced at the cathode Since the oxidative decomposition product floats in the electrolytic bath due to the difference in specific gravity with the mixed molten salt, titanium oxide can be reduced efficiently, and the gas such as carbon dioxide generated at the carbon anode is along the inclined guide surface. Since the gas floating region is limited, the deposited titanium metal can be prevented from being contaminated by carbon dioxide gas, and the titanium metal can be efficiently produced without causing a reaction unrelated to the reduction.
[0042]
In the present invention, the consumable carbon anode having the shape having the guide inclined surface as described above is formed of the aggregated coke primary calcined carbon material obtained by combining the control of the particle size distribution and the calcining temperature described above. It was obtained by using such an aggregate coke as a coal-based coke, and further using this coal-based coke as deashed, or using a pitch obtained by deashing a binder of the primary calcined carbon material. Combining what is meant can further improve the anti-contamination effect of titanium metal obtained when used as a consumable carbon anode for metal titanium smelting.
[0043]
【Example】
Hereinafter, the present invention will be described more specifically based on test examples and examples.
[0044]
[Test Example 1]
In order to investigate the influence of the difference in the particle size distribution of the aggregate coke on the fired bulk specific gravity, electrical resistivity, and bending strength of the carbon anode, the following measurements were performed.
First, coal-based coke (sample numbers 1 to 11) adjusted to the particle size distribution shown in Table 1 and binder pitch composed of deashed coal-based pitch are mixed, and the temperature is 150 ° C. and the pressure is 200 kgf / cm. ² 6 pieces each having a diameter of 40 mm and a height of 120 mm prepared by mold-molding for 1 minute were prepared and fired at 980 ° C. Each fired sample is processed into a diameter of 36 mm x height 116 mm to prepare a sample piece to be used as a test carbon anode. Thereafter, bulk specific gravity and bending strength are measured according to JIS R7212, and four terminals using a Kelvin double bridge are used. The electrical resistivity was measured by the potential drop method (also referred to as “basic characteristic test”). These results are shown in Table 2.
[0045]
[Table 1]

[0046]
[Table 2]

[0047]
Next, for each sample piece obtained above, CO ₂ Oxidation consumption rate, CO ₂ Total oxidation consumption (also called “CO ₂ The measurement of “Oxidation consumption test” was performed as follows.
First, a sample piece is placed on the pan balance in the test apparatus, and is kept at 980 ° C. so that the inside of the test apparatus is in a nitrogen gas atmosphere. ₂ A gas of 1.75 liters / min was fed. After that, when the weight loss of the sample piece reaches 6.0 g, the gas to be fed is changed to CO again. ₂ The gas was switched from nitrogen gas to cooling in a nitrogen gas atmosphere. Then, an impact is applied to each sample piece taken out, the loose carbon is forcibly dropped, the amount of dropped carbon and the remaining carbon, and the amount of carbon that has naturally dropped into the test apparatus are weighed, and CO ₂ Oxidation consumption rate and CO ₂ The total oxidation consumption was determined. The results are shown in Table 2.
CO ₂ Oxidation consumption rate (g / hr) = amount of gasification / reaction time
CO ₂ Total oxidation consumption (%) = 100 + (forced dropout amount + natural dropout amount) / gasification amount x 100
Gasification amount = specimen weight before test-(forced dropout amount + natural dropout amount + residual amount)
[0048]
Moreover, the electrolytic consumption test by the aqueous solution electrolysis which used each sample piece obtained above as an anode and made 4N-NaOH aqueous solution into electrolyte was conducted as follows.
First, the center part of each sample piece was threaded and a brass conductive rod was screwed to form an anode. The anode was attached to a 1000 ml beaker in which a SUS cylindrical tube was previously fixed as a cathode, and the height was adjusted and fixed. Then, 4N-NaOH aqueous solution was poured into the beaker until the sample piece reached a certain height, and 0.5 A / cm. ² The electrolysis was performed through the direct current. When the total current reached 200 A, the current was stopped, the anode was removed from the brass conductive rod, washed with water, dried and weighed. Further, the electrolytic solution containing the dropping carbon was filtered through a filter, the dropping carbon was dried and weighed, and the total consumption rate and the selective oxidation degree were determined by the following equations. The obtained results are shown in Table 2. The theoretical gasification amount is obtained by theoretical calculation of the amount of gasification reaction from the energization amount in the electrolysis.
Total consumption rate (g / A hr) = (theoretical gasification amount + falling carbon amount) / total current amount × (elapsed time)
Selective oxidation degree (%) = amount of dropped carbon / theoretical gasification amount x 100
[0049]
As can be seen from Table 2 showing the above results, basic characteristic tests as electrode materials, CO ₂ As for the oxidation consumption test and the electrolytic test, it was found that favorable results were obtained in the case of sample numbers 3 to 7. In Table 2, the bulk specific gravity, electrical resistivity, and bending strength are average values of n = 6, and CO 2 ₂ The oxidation consumption test and the electrolytic test are shown as an average value of n = 2.
[0050]
Next, using coal-based coke with a calcining temperature of 1300 ° C adjusted to the particle size distribution shown in Table 1, mixed with binder pitch made of decalcified coal-based pitch, mold for 1 minute at a temperature of 150 ° C and a pressure of 200 kgf. After forming a block which was molded and fired at 980 ° C., a crucible type carbon anode sample having an inner diameter of 120 mmφ and a height of 200 mm (inner dimensions) was prepared, and calcium chloride (CaCl ₂ ) And calcium oxide (CaO) were electrolyzed, and the current value was measured over time.
A SUS round bar was connected to the crucible wall so that it could be energized later as an anode, and this crucible was placed in an electric furnace assembled with a SiC resistor and dried. Then pre-mixed CaCl ₂ A mixed salt composed of +2 mol% CaO was put in this crucible, and the temperature was raised to 900 ° C. while passing Ar gas. In the middle of the temperature increase, the amount of mixed salt was added sequentially in anticipation of the volume reduction accompanying dissolution of the mixed salt, and finally 3.5 kg of mixed molten salt was prepared. After the entire amount was dissolved, an SUS cathode was placed and fixed at the center of the crucible and placed in the molten salt, and electrolysis was performed by applying a constant voltage of 2.8 V between the carbon anode and the SUS cathode. After about 4 hours, the electrolysis was stopped, the SUS cathode was pulled up to the top of the electrolytic bath, the electric furnace was turned off, and the molten salt, crucible type carbon anode, and SUS cathode were cooled in an Ar atmosphere. As an example, the current value measurement results of Sample No. 5 and Sample No. 9 are shown in the graph of FIG.
[0051]
In the time measurement of the current value in the electrolysis, bubbles of carbon dioxide gas were generated from the surface of the crucible-type carbon anode with the start of electrolysis, and current began to flow. Oxygen ions or the like can be considered as a medium through which this current flows, and as time passes, oxygen ions are consumed as carbon dioxide gas and discharged out of the system, so that the current value decreases at a constant voltage. However, as shown in FIG. 1, in Sample No. 9, the current value increased after 150 minutes from the start of electrolysis. This is presumably because floating carbon generated from the crucible type carbon anode was significantly deposited between the crucible type carbon anode and the SUS cathode, and both electrodes were short-circuited to generate a detour current. This tendency for the current value to increase is remarkable for sample numbers 1, 2, and 8 to 11, and for sample numbers 3 to 7, this increase trend was suppressed to a small level.
[0052]
From Test Example 1, it is possible to control the packing density of the aggregate coke particles by controlling the particle size distribution of the aggregate coke. Even when the primary calcined carbon material is a consumable carbon anode, the strength characteristics, electrical It can be seen that the hot reaction stability such as characteristics and uniformity of oxidation consumption is excellent, and that free carbon during electrolysis can be reduced.
[0053]
[Test Example 2]
Depending on the calcining temperature of aggregate coke, basic characteristics test of carbon anode, CO ₂ In order to investigate the influence on the results of the oxidation consumption test and the electrolytic test, the following measurements were performed.
As shown in Table 3, aggregate coke samples having different calcination temperatures were prepared (sample numbers 12 to 17). This aggregate coke has a particle size distribution in which the particle size of 0.074 mm or less is 18% by weight and the particle size of 3.0 mm or more is 30% by weight based on the results of Test Example 1, and the same as in Test Example 1 above. A sample piece was prepared. Sample No. 17 was obtained from a graphite molded material obtained by performing secondary firing at 2500 ° C. after performing primary firing at 980 ° C. using aggregate coke having a calcining temperature of 1300 ° C. for reference purposes. A sample piece was obtained.
For the sample piece, the basic characteristic test, CO ₂ An oxidation consumption test and an electrolytic test were performed. The results are shown in Table 4.
[0054]
[Table 3]

[0055]
[Table 4]

[0056]
From the results shown in Table 4 above, the sample pieces obtained using aggregate coke having a low calcination temperature have a low degree of selective oxidation, and in particular, sample pieces having a calcination temperature of 1200 ° C. or less (sample numbers 14 to 16). ), A value close to that of the sample piece (sample number 17) obtained from the graphite molding material was used for the comparative example.
[0057]
From Test Example 2, it can be seen that by controlling the calcining temperature of the aggregate coke, it is possible to prevent the aggregate coke from falling off due to the selective oxidation of the binder coke and to reduce the amount of free carbon.
[0058]
[Test Example 3]
In order to investigate the influence of contamination on the metal titanium obtained when the metal titanium was smelted using the carbon anode formed from the difference in the material of the aggregate coke, the following test was conducted.
First, petroleum-based coke, coal-based coke and decalcified coal-based coke having a calcination temperature of 1000 ° C., each having a particle size of 0.074 mm or less and 18% by weight, and a particle size of 3.0 mm or more. A sample having a particle size distribution of 30% by weight was prepared (sample numbers 18 to 20), mixed with a binder pitch composed of decalcified coal-based pitch, formed into a block, fired at 980 ° C, an inner diameter of 120 mm, A crucible type carbon anode having a height of 200 mm (inner dimensions) was produced. Also, a crucible-type carbon anode similar to the above using a graphite molding material obtained by first firing at 980 ° C. using aggregate coke having a calcining temperature of 1300 ° C. and further firing at 2500 ° C. Prepared (Sample No. 21).
[0059]
A SUS round bar was connected to the wall of the crucible-type carbon anode and processed so that it could be energized later as an anode. This crucible-type carbon anode is placed in an electric furnace with a SiC resistor and dried, and then pre-mixed CaCl ₂ A mixed salt composed of +2 mol% CaO was put in this crucible, and the temperature was raised to 900 ° C. while passing Ar gas. In the middle of the temperature increase, the amount of mixed salt was added sequentially in anticipation of the volume decrease accompanying dissolution of the mixed salt, and finally 3.5 kg of mixed molten salt was prepared. After the entire amount is dissolved, a SUS cathode is put in the molten salt, a constant voltage of 1.0 V is applied, and moisture and impurities that are initially present in the molten salt are iron (Fe), vanadium (V), and sulfur ( Pre-electrolysis was performed to remove those that could be removed in advance.
[0060]
After the preliminary electrolysis, the SUS cathode was pulled out, and a titanium cathode for molten salt electrolysis was inserted into the crucible. This titanium cathode is made by rolling a titanium net into a cylindrical shape with an inner diameter of 8 mmφ and a height of 140 mm and sealing the bottom with an 8 mmφ titanium round bar to form a titanium net container. Is covered with an 8mmφ titanium round bar so that it can be connected to a power source for electrolysis. The titanium cathode is placed and fixed at the center of the crucible and at a depth where all the titanium oxide is immersed in the molten salt, and a constant voltage of 2.8 V is applied between the carbon anode and the titanium cathode to Electrolysis was performed. After about 4 hours, the electrolysis was stopped, the titanium cathode was pulled up to the top of the electrolytic bath, the electric furnace was turned off, and the titanium cathode and the molten salt were cooled in an Ar atmosphere.
[0061]
After cooling to room temperature, the titanium cathode was lifted from the electric furnace and washed with ice water to recover internal titanium (titanium oxide at the time of charging). The recovered titanium was dried in a temperature-controlled desiccator and then analyzed by fluorescent X-ray analysis and infrared absorption method. From these analysis results, it was found that the total amount of recovered titanium was reduced to metallic titanium. The above contents were carried out for the carbon anode obtained from each sample, and the concentration of impurities contained in the recovered metal titanium is shown in Table 5.
[0062]
[Table 5]

[0063]
From Table 5 above, the concentration of iron, sulfur, and vanadium is highest when petroleum coke is aggregate coke, followed by coal-based coke, deashed coal-based coke, and graphite molding. It was. On the other hand, regarding the carbon concentration in the titanium metal, the values of the graphite molding material and the other aggregate coke were almost equal.
[0064]
From this Test Example 3, the aggregate coke is made of coal-based coke and decalcified coal-based coke, so that it is almost the same as the graphite molding material that performs secondary firing even for a cheaper primary fired carbon material. It can be seen that the migration of impurities into the molten salt can be reduced and that high-purity titanium metal can be produced.
[0065]
[Test Example 4]
In order to limit the gas floating region when the gas generated from the carbon anode floats in the molten salt by electrolysis, the following test was performed.
In order to facilitate visual understanding, FIGS. 2 and 3 are photographs showing the state of electrolysis using a water model. A water tank 1 made of an acrylic plate with a width of 850 mm x depth of 850 mm x height of 1000 mm is prepared as if it were an electrolytic cell, which is a reaction tank. 2 in which the filter 3 is bonded to the side surface 2 a of the hollow iron plate 2. From the center of the upper surface 2b of the hollow iron plate 2, the amount of gas considered to be generated by the actual electrolysis of the molten salt is calculated, compressed air is blown, and gas is blown out from the filter 3 bonded to the side surface 2a. The state of the gas rising on the side surface 2a of the iron plate 2 was observed. 2 shows a case where the side surface 2a of the hollow iron plate 2 is at an angle of 0 degrees with respect to the vertical direction, and FIG. 3 shows a guide inclined surface in which the side surface 2a is inclined in an overhanging manner at an angle of 12 degrees with respect to the vertical direction. It shows the case. As is apparent from FIGS. 2 and 3, it can be seen that the width (L) of the bubble floating region floating on the water surface 1a can be limited to be smaller when the overhang is inclined.
[0066]
From Test Example 4, it can be seen that by providing a guide inclined surface inclined in an overhang shape on the side surface of the carbon anode, it is possible to control the floating region of the gas generated at the carbon anode.
[0067]
[Test Example 5]
Using the consumable carbon anode 8 shown in FIG. 4, metal titanium was smelted by the metal titanium smelting apparatus 4 as shown in FIG.
A mixed salt of calcium chloride containing calcium oxide was put in the magnetic crucible 5 and held at 900 ° C. to obtain a mixed molten salt 6, and preliminary electrolysis for dehydration and impurity removal was performed in advance. Next, a cathode plate 7 made of a titanium plate is disposed so as to be inclined at 5 degrees with respect to the bottom surface of the magnetic crucible 5. Above the cathode plate 7, the calcining temperature is 1000 ° C. and the particle diameter is 0.074 mm or less. It is obtained by mixing coal-based aggregate coke having a particle size distribution of 18% by weight and particle size of 3.0 mm or more and 30% by weight with binder pitch composed of deashed coal-based pitch and calcining at 980 ° C. A consumable carbon anode 8 was placed (Sample No. 22). The consumable carbon anode 8 is processed so that the bottom surface 8a of the consumable carbon anode immersed in the mixed molten salt 6 is inclined at an angle of 85 degrees with respect to the vertical direction. And a distance X between the bottom surface 8a and the cathode plate 7 was set to 30 mm. Further, a titanium conductive rod 9 is attached to the consumable carbon anode 8 and connected to a positive terminal of a DC power source (not shown), and a titanium conductive rod 10 is attached to the end of the cathode plate 7. And connected to a negative terminal of a DC power supply (not shown). The portion immersed in the mixed molten salt 6 other than the cathode plate 7 is covered with a magnesia protective tube 11.
[0068]
Under such circumstances, 10 g of titanium oxide 12 was submerged on the cathode plate 7, and a current of 20 A was passed between the electrodes to conduct electrolysis with a constant current. In this electrolysis, carbon dioxide gas (CO generated in the bottom surface 8a of the consumable carbon anode 8 is used. ₂ Since the gas such as) is guided and rises in a certain direction due to the inclination applied to the bottom surface 8a, the bottom surface 8a functions as a guide inclined surface and restricts the gas floating region.
[0069]
Further, metal titanium was smelted by the metal titanium smelting apparatus 13 as shown in FIG. 7 using the consumable carbon anode 17 shown in FIG.
A mixed salt of calcium chloride containing calcium oxide was put in the magnetic crucible 14 and held at 900 ° C. to obtain a mixed molten salt 15, which was previously subjected to preliminary electrolysis for dehydration and impurity removal. Next, the mixed molten salt 15 is provided with a cathode plate 16 made of a metal titanium plate having an inclination of 15 degrees with respect to the vertical direction, and has a calcination temperature of 1000 ° C. and a particle size of 0.074 mm or less. Is obtained by mixing coal-based aggregate coke having a particle size distribution of 18% by weight with a particle size of 3.0 mm or more and 30% by weight and a binder pitch composed of deashed coal-based pitch and firing at 980 ° C. A consumable carbon anode 17 was placed (Sample No. 23). The consumable carbon anode 17 is processed so that a side surface 17a immersed in the mixed molten salt 16 is inclined in an overhanging manner at an angle of 15 degrees with respect to the vertical direction. The distance Y between the side surface 17a and the cathode plate 16 is set to 25 mm. Further, a box-shaped container 18 made of a titanium net is disposed at a position between the inner wall surface of the magnetic crucible 14 and the cathode plate 16 so as to be immersed in the mixed molten salt 15. A titanium conductive rod 19 is attached to the consumable carbon anode 17 and connected to a positive terminal of a DC power source (not shown), and a titanium conductive rod 20 is attached to the end of the cathode plate 16. It is connected to the negative terminal of a DC power supply not shown.
[0070]
Under such circumstances, 10 g of titanium oxide 21 was placed in the box-shaped container 18, and a current of 20 A was passed between both electrodes to conduct electrolysis with a constant current. In this electrolysis, carbon dioxide (CO 2) generated on the side surface 17a of the consumable carbon anode 17 ₂ Since the gas such as) is guided and rises in a certain direction by the inclination attached to the bottom surface 17a, the bottom surface 17a functions as a guide inclined surface, and restricts the gas floating region.
[0071]
Note that the difference (5 mm) in the distance between the electrodes in Sample No. 22 and Sample No. 22 is that titanium oxide is submerged between the carbon anode and the cathode in Sample No. 22, so The thickness (5 mm) is taken into consideration. Further, in the titanium metal smelting apparatus 13, a consumable carbon anode (sample) in which the cathode plate is arranged parallel to the vertical direction and the side surface of the carbon anode is not parallel to the vertical direction. In the case of No. 24), electrolysis was performed in the same manner as above except for the other conditions.
[0072]
In Test Example 5, the electrolysis was terminated when an amount of electricity 1.5 times the theoretical amount of electricity necessary to reduce the total amount of titanium oxide to metallic titanium with an efficiency of 100% was passed. The anode was pulled out and cooled to room temperature under an argon atmosphere. Further, the submerged titanium oxide was recovered in a powder state after being washed with water and diluted hydrochloric acid together with the magnetic crucible. The collected substance was dried in a temperature-controlled desiccator and then analyzed by X-ray diffraction analysis, fluorescent X-ray analysis, and infrared absorption method. The respective analysis results are shown in Table 6.
[0073]
[Table 6]

[0074]
In Sample Nos. 22 and 23 in which the consumable carbon anode has a guide inclined surface, it was found that the entire amount of the recovered substance was reduced to titanium metal. On the other hand, in sample number 24 in which the consumable carbon anode does not have a guide inclined surface, it was found that titanium carbide (TiC) indicating that metal titanium was contaminated by carbon was mixed in addition to metal titanium. The quality of titanium was insufficient.
[0075]
【The invention's effect】
According to the present invention, by using a carbon anode formed of a primary calcined carbon material of aggregate coke, which is cheaper than a graphite molded material subjected to secondary firing, as a consumable carbon anode for metal titanium smelting, Titanium metal can be produced in an industrially advantageous manner, and the obtained titanium metal is not contaminated. Compared to the case where the graphite molded material subjected to secondary firing is used as a consumable carbon anode, the quality is also improved. There is no dark blue.
[Brief description of the drawings]
FIG. 1 is a graph showing a change in current value over time in electrolysis in an inorganic molten salt.
FIG. 2 is a model for expressing the state of gas generated from a consumable carbon anode during electrolysis, in which a compressed iron gas is sent by submerging a hollow iron plate that is regarded as a consumable carbon anode into a water tank. It is a picture of the state (when the side surface of the carbon anode is not inclined).
FIG. 3 is a model for representing the state of gas generated from a consumable carbon anode during electrolysis, in which a compressed iron gas is fed by submerging a hollow iron plate that looks like a consumable carbon anode into a water tank. It is a picture of the state (when the side of the carbon anode is inclined).
FIG. 4 is a perspective explanatory view showing a consumable carbon anode according to Test Example 5 of the present invention.
FIG. 5 is an explanatory cross-sectional view showing a titanium metal smelting apparatus according to Test Example 5 of the present invention.
FIG. 6 is a perspective explanatory view showing another consumable carbon anode according to Test Example 5 of the present invention.
FIG. 7 is a cross-sectional explanatory view showing another metal titanium smelting apparatus according to Test Example 5 of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Water tank, 1a ... Water surface, 2 ... Hollow iron plate, 2a ... Side surface of hollow iron plate, 2b ... Upper surface of hollow iron plate, 3 ... Filter, 4, 13 ... Metal titanium smelting device, 5, 14 ... Magnetic crucible, 6, 15 ... Mixed molten salt, 7, 16 ... Cathode plate, 8 ... Consumable carbon anode, 8a ... Bottom surface of consumable carbon anode, 9, 10, 19, 20 ... Titanium conductive rod, 11 ... Magnesia protective tube, 12 , 21 ... titanium oxide, 17 ... consumable carbon anode, 17a ... side of the consumable carbon anode, 18 ... box-type container.

Claims (8)

It is a consumable carbon anode for smelting metal titanium used for smelting metal titanium that forms an electrolytic bath of an inorganic molten salt in a reaction tank and reduces titanium oxide using an electrolysis method,
Aggregate coke primary calcined carbon having a particle size distribution in which the carbon anode has a particle size of 0.074 mm or less and 15 wt% or more and 25 wt% or less and a particle size of 3.0 mm or more and 22 wt% or more and 37 wt% or less. A consumable carbon anode for metal titanium smelting, characterized by being made of a material. The consumable carbon anode for metal titanium smelting according to claim 1, wherein the aggregate coke used for the primary calcined carbon material is coal-based coke . The consumable carbon anode for titanium metal smelting according to claim 2 , wherein the coal-based coke is deashed. The consumable carbon anode for smelting of titanium metal according to any one of claims 1 to 3, wherein the primary calcined carbon material uses a deashed pitch as a binder . It is a consumable carbon anode for smelting metal titanium used for smelting metal titanium that forms an electrolytic bath of an inorganic molten salt in a reaction tank and reduces titanium oxide using an electrolysis method,
The carbon anode has a guide inclined surface inclined in an overhang at an angle of 1 to 45 degrees with respect to a vertical direction on a side surface facing at least parallel to the cathode used in electrolysis and immersed in the inorganic molten salt. A consumable carbon anode for smelting of titanium metal , characterized in that the gas generated from the carbon anode and rising by the guide inclined surface is guided along the guide inclined surface . In the metal titanium smelting process, a part of the inorganic molten salt forming the electrolytic bath is electrolyzed to produce a reductive decomposition product, and titanium oxide is produced by thermally reducing titanium oxide with the generated reductive decomposition product. There,
The inorganic molten salt is a mixed molten salt composed of calcium chloride ( CaCl ₂ ) and calcium oxide ( CaO ) and / or calcium ( Ca ), and an electrolytic bath formed by the mixed molten salt is used for the electrolysis. An electrolysis zone for electrolyzing calcium oxide and / or calcium chloride in the mixed molten salt depending on the cathode used, and a reduction zone for reducing titanium oxide by calcium ( Ca ) and monovalent calcium ions ( Ca ⁺ ) generated in the electrolysis zone It is a consumable carbon anode for metal titanium smelting used for metal titanium smelting to produce metal titanium divided into
The guide slope in which the carbon anode is inclined in an overhanging manner at an angle of 1 to 45 degrees with respect to the vertical direction on the side face facing at least parallel to the cathode in the electrolytic zone and immersed in the mixed molten salt 6. A consumable carbon anode for smelting of titanium metal according to claim 5, which has a surface and guides the gas generated and raised from the carbon anode by the guide inclined surface along the guide inclined surface . It is a consumable carbon anode for smelting metal titanium used for smelting metal titanium that forms an electrolytic bath of an inorganic molten salt in a reaction tank and reduces titanium oxide using an electrolysis method,
The carbon anode has a guide inclined surface with an angle of 80 to 90 degrees with respect to the vertical direction on the bottom surface that is at least parallel to the cathode used in electrolysis and immersed in the inorganic molten salt. A consumable carbon anode for metal titanium smelting characterized by guiding a gas generated from a carbon anode by a surface and rising along a guide inclined surface . In the metal titanium smelting process, a part of the inorganic molten salt forming the electrolytic bath is electrolyzed to produce a reductive decomposition product, and titanium oxide is produced by thermally reducing titanium oxide with the generated reductive decomposition product. There,
The inorganic molten salt is a mixed molten salt composed of calcium chloride ( CaCl ₂ ) and calcium oxide ( CaO ) and / or calcium ( Ca ), and is substantially parallel to the bottom surface of the reaction vessel in the mixed molten salt. A cathode located above and a consumable carbon anode located above the cathode are disposed, and the calcium oxide and / or calcium chloride in the mixed molten salt is electrolyzed between the electrodes and produced by this electrolysis. A consumable carbon anode for metal titanium smelting used in metal titanium smelting to produce titanium metal by reducing titanium oxide with calcium ( Ca ) and monovalent calcium ions ( Ca ⁺ ),
The carbon anode, at least on the bottom immersion in molten salt mixture with the cathodic parallel to phase face has an inclined guide surface 80 to 90 degree angle with respect to the vertical direction, more to the guide inclined surfaces The consumable carbon anode for smelting of titanium metal according to claim 7, wherein the gas generated from the carbon anode and rising is guided along the guide inclined surface .

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