JPS6235966B2 - - Google Patents
Info
- Publication number
- JPS6235966B2 JPS6235966B2 JP11867980A JP11867980A JPS6235966B2 JP S6235966 B2 JPS6235966 B2 JP S6235966B2 JP 11867980 A JP11867980 A JP 11867980A JP 11867980 A JP11867980 A JP 11867980A JP S6235966 B2 JPS6235966 B2 JP S6235966B2
- Authority
- JP
- Japan
- Prior art keywords
- liquid
- slag
- extract
- extraction tank
- extraction
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000000605 extraction Methods 0.000 claims description 68
- 239000007788 liquid Substances 0.000 claims description 59
- 239000002893 slag Substances 0.000 claims description 45
- 238000000034 method Methods 0.000 claims description 26
- 229910052783 alkali metal Inorganic materials 0.000 claims description 20
- 150000001340 alkali metals Chemical class 0.000 claims description 20
- 230000005484 gravity Effects 0.000 claims description 16
- 150000001339 alkali metal compounds Chemical class 0.000 claims description 13
- 229910052751 metal Inorganic materials 0.000 claims description 12
- 239000002184 metal Substances 0.000 claims description 12
- 238000010992 reflux Methods 0.000 claims description 11
- 238000007670 refining Methods 0.000 claims description 10
- 239000002562 thickening agent Substances 0.000 claims description 10
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 6
- 229920006395 saturated elastomer Polymers 0.000 claims description 4
- 238000007664 blowing Methods 0.000 claims description 3
- 239000001569 carbon dioxide Substances 0.000 claims description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 3
- 239000006228 supernatant Substances 0.000 claims description 2
- 239000011734 sodium Substances 0.000 description 54
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 21
- 238000003756 stirring Methods 0.000 description 14
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 12
- 239000012530 fluid Substances 0.000 description 11
- 239000003795 chemical substances by application Substances 0.000 description 8
- 238000011084 recovery Methods 0.000 description 8
- 238000002425 crystallisation Methods 0.000 description 7
- 230000008025 crystallization Effects 0.000 description 7
- 230000007423 decrease Effects 0.000 description 7
- 239000007789 gas Substances 0.000 description 7
- 239000011555 saturated liquid Substances 0.000 description 7
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical group [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 238000010586 diagram Methods 0.000 description 6
- 229910052698 phosphorus Inorganic materials 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- 229910052717 sulfur Inorganic materials 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 235000017550 sodium carbonate Nutrition 0.000 description 5
- 229910000029 sodium carbonate Inorganic materials 0.000 description 5
- 238000003723 Smelting Methods 0.000 description 4
- 238000006477 desulfuration reaction Methods 0.000 description 4
- 230000023556 desulfurization Effects 0.000 description 4
- 238000001704 evaporation Methods 0.000 description 4
- 230000008020 evaporation Effects 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 3
- 229910004298 SiO 2 Inorganic materials 0.000 description 3
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 3
- 239000000292 calcium oxide Substances 0.000 description 3
- 235000012255 calcium oxide Nutrition 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000011574 phosphorus Substances 0.000 description 3
- 239000011593 sulfur Substances 0.000 description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 description 2
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000010828 elution Methods 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000010979 pH adjustment Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 239000012047 saturated solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
- WCTAGTRAWPDFQO-UHFFFAOYSA-K trisodium;hydrogen carbonate;carbonate Chemical compound [Na+].[Na+].[Na+].OC([O-])=O.[O-]C([O-])=O WCTAGTRAWPDFQO-UHFFFAOYSA-K 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Description
この発明は、溶銑を、アルカリ金属化合物を使
用して脱硫および／あるいは脱燐精錬を行なう際
に生成するスラグより、アルカリ金属を回収す
る、アルカリ金属化合物を含有する精錬スラグの
処理方法に関するものである。
溶銑は、一般にその成分として、Ｃ：3.5〜4.8
％、Si：0.2〜1.0％、Ｓ：0.02〜0.05％、Ｐ：0.1
〜0.18％程度を含有しているが、近年、鋼材の使
用条件の苛酷化に伴なつて、高級鋼の精錬比率が
増加し、その成分中に含有するＳ、Ｐ等の不純物
を可及的に低くすることが要求されている。
通常、酸素製鋼法による精錬に当つて、溶銑の
脱硫、脱燐処理のためには、生石灰を主成分とす
る造滓剤が使用されているが、この生石灰を主成
分とする造滓剤では上記要求を満すことができな
い。そのため酸素製鋼法による精錬の前に、炭酸
ナトリウムあるいはカーバイドを使用し、溶銑を
炉外で予備脱硫処理をすることも行なわれている
が、このような予備脱硫処理を行なつても、前記
した要求を満すには十分とは云えない。
上記した溶銑の脱硫、脱燐効果を高めるため
に、生石灰に比べ、燐および硫黄との結合力が強
い造滓剤として、アルカリ金属化合物例えば炭酸
ナトリウム（ソーダ灰）を使用し精錬を行なう方
法が、米国特許第2147205号、英国特許第782192
号等により知られている。この方法によれば、溶
銑中の燐および硫黄をほぼ所望通りに低減せしめ
ることができる。
しかし、この方法は、炭酸ナトリウムの価格が
高く、生石灰の約４倍にもなり、その原単位が大
となる等、工業的に実用化する上で多くの問題が
あつた。
上記問題を解決する手段として、最近、アルカ
リ金属化合物を主成分とする造滓剤を使用して溶
銑の予備精錬を行ない、燐、硫黄等の不純物を除
去するとともに、この精錬により発生したスラグ
から、アルカリ金属を炭酸含有塩として回収し、
これを再び精錬の際の造滓剤として循環使用する
方法が研究開発され、特開昭52−122214号、特開
昭53−102213号ほか多くの特許が出願されてい
る。
この方法は、アルカリ金属化合物を主成分とす
る造滓剤を使用して溶銑の予備精錬を行なう際に
生成するスラグが、例えば、Na：10〜60％、
Si：１〜15％、Ｐ：0.5〜22％、Ｓ：0.1〜２％の
如き成分組成を有し、かつ水溶性であることか
ら、このスラグをスラグ重量の２〜20倍の水ある
いは水を主成分とする溶液に溶解させ、この水溶
液に化学処理を施してNa2Oを抽出し、これを回
収するものである。
しかるに、この方法でスラグを水に溶解する
と、スラグ中に含まれているFe、Mn、Si等の酸
化物を主成分とした不溶解残渣が、元のスラグ重
量に対する割合（以下、「不溶解残渣率」とい
う）で、30〜50％も生じ、スラグの成分組成によ
つては、60％以上にもなる場合がある。
このように不溶解残渣率の大きいスラグ溶液
は、その水−スラグ比（以下、「水比」という）
が約５以上の比較的大きい場合には、通常の円筒
型撹拌槽を使用し抽出作業を行なうことができる
が、後工程のNa炭酸含有塩の晶析工程における
作業を効率よく行なうためには、前記晶析工程の
前段階において、Naの濃度を増すための蒸発濃
縮工程を必要とし、ソーダの回収コストが高価と
なる問題があつた。一方、前記水比が４以下に小
さい場合には、抽出液中のNa2O濃度が高くなる
から、前記蒸発濃縮工程は必要でなく、ソーダ回
収コストが高価となることはないが、その反面、
抽出液の不溶解渣濃度および粘度が高くなる結果
抽出工程における撹拌が困難となり、抽出槽の撹
拌操作性が悪化する問題があつた。
また、上記水比を1.5〜3.5となし、スパイラル
羽根送り型抽出装置により抽出を行なう方法（例
えば特開昭54−100999号）も知られているが、こ
の方法では、抽出性能を向上させるために不可欠
な撹拌作業が不十分であり、この結果、抽出装置
を複数基直列に設定して行なう多段抽出が必要と
なつて、設備コストの増加、設備面積の増大等を
招いていた。
更に、従来の方法では、スラグを単に水で溶解
しているので、スラグ中のNa2Oは、水にNaOH
の形で抽出される。NaOHは１モル40ｇであるか
ら、１の水にスラグを40ｇ溶解（即ちNa2Oと
して約３％）すればPH14.4ｇ溶解（即ちNa2Oと
して約0.3％）すればPH13となる。逆に言えば、
PH13〜14で抽出しても、Na2Oは0.3〜３％となる
だけである。そして、このようにPHが13〜14とな
るため、溶液中にNa2Oと共に不純物であるSiO2
が約30〜50％も溶出する。この結果、溶液の粘度
が高くなり、不溶解残渣の過性が極めて悪化す
る問題があつた。
また、スラグ中のNa2O含有率は一定ではな
く、例えば25％〜45％内で変動する。その結果、
溶液中のNa2O濃度に変動が生ずるが、従来はこ
のようなNa2O濃度の変動に対する管理が行なわ
れていないため、Na2Oの回収歩留が悪く、プロ
セスの操業上からも種々の悪影響が生じていた。
この発明は、上述のような観点から、アルカリ
金属化合物を主成分とする造滓剤を使用して、溶
銑の精錬を行なう際に生成するスラグより、アル
カリ金属を抽出するに当り、晶析工程の前段階に
おける抽出液の蒸発濃縮工程を不要にし、しかも
抽出工程における撹拌操作性を良好にし、また抽
出液中の不溶解残渣濃度を低め、かつ抽出液のア
ルカリ金属濃度を一定範囲に保持することによ
り、アルカリ金属の回収歩留を高め、これらによ
つて効率的にアルカリ金属の抽出を行なうことが
できる、アルカリ金属化合物を含有する精錬スラ
グの処理方法を提供するもので、溶銑をアルカリ
金属化合物を使用して精錬する際に生成するスラ
グを、抽出槽において、Na2O−CO2−H2O系の
循環液と還流液の混合液からなる被抽出液中に溶
解させて得た抽出液からアルカリ金属を回収する
アルカリ金属化合物を含有する精錬スラグの処理
方法において、前記抽出槽における、前記循環液
のスラグに対する比を小にした上、前記抽出槽中
に、前記抽出液のシツクナーにおける上登液、お
よび／あるいは、前記抽出液の不溶解残渣分離
液の一部を還流液として還流して、前記抽出槽に
おける前記抽出液のスラグに対する比を４以上に
なすと共に、前記抽出液の比重を飽和比重未満に
制御し、且つ、前記抽出槽中への炭酸ガスの吹込
みによりPHを制御することにより、前記抽出液中
のアルカリ金属濃度を一定値に保持することに特
徴を有するものである。
次に、この発明を図面と共に説明する。
第１図には、この発明方法の一例が系統図によ
り示されている。図面において、１は通常の円筒
型撹拌槽からなる抽出槽、２は抽出槽１内に設け
られた気液接触装置、３は抽出槽１の出側に設け
られたポンプ、４はシツクナー、５は分離機であ
る。アルカリ金属化合物を主成分とする造滓剤を
使用して溶銑の処理を行なつたときに生成したス
ラグは、抽出作業性を高めるため予め、通常の粉
砕機を使用して、20mmφ以下、望ましくは10mmφ
以下に粉砕して整粒した後、テーブルフイーダ、
ロータリーフイーダ等の通常の粉体供給装置（図
示せず）により、抽出槽１に供給する。
抽出槽１におけるスラグ中の含有成分を抽出す
るための被抽出液としては、後工程の晶析工程に
おいて、Naを重炭酸塩として60℃以下の比較的
低温により晶析回収する分離液である、Na2O
−CO2−H2O系飽和液の循環液（以下、「循環
液」という）ａと、シツクナー４および／あるい
は分離機５から抽出槽１へ還流される還流液ｂの
混合液を使用する。
一般に、スラグ中のNaを重炭酸塩として晶析
し回収するためには、晶析槽における過液のPH
を9.5以下、望ましくは９以下に管理することが
必要となる。そのため、抽出槽１内に送られる前
記循環液ａのPHも当然9.5以下、あるいは９以下
となる。
そこで、本発明者等は、Na2O−CO2−H2Oの
系飽和液のPHと、前記液中のNa2O溶解度との関
係について調べたところ、第２図の如き関係のあ
ることがわかつた。即ち、第２図はNa2O−CO2
−H2O−系飽和液のPHとの関係におけるNa2Oの
溶解度曲線を示す一般図である。図面において、
白丸印は液の温度が60℃の場合、黒丸印は液の温
度が35℃の場合である。図面に示す如く、液のPH
が9.5以下の場合は、液中のNa2Oの溶解度は４〜
5.5％であるのに対し、液のPHが10.5以上になる
と、液中のNa2Oの溶解度は15〜19％に上る。な
お前記溶解度は液の抽出能力のことであり、飽和
まで抽出するということではない。そこで、抽出
槽１内における抽出液のPHを10.5〜11.5に制御
し、これによつて循環液ａのNa2O溶解度を15〜
19％に高めることが出来る。即ち、循環液ａの溶
解力としては、PH10.5〜11.5におけるNa2O溶解度
と、PH9.5以下におけるNa2O溶解度との差に相当
する量になる。つまり
（15〜19％）−（４〜5.5％）
となり、約10〜15％のNa2O溶解能力を有するこ
とになり、従来の0.3〜３％に比べて高くなるの
である。このような循環液ａ中へのNa2Oの溶解
は、第１図に示すように気液接触装置２を用い、
ガス供給管２′から炭酸ガスを吹き込みながら行
なわれるので、抽出槽１内の抽出液は、Na2O−
CO2−H2O系更に具体的にはNa2CO3−NaHCO3
−H2O系を形成する。従つて、PH10.5〜11.5で、
Na2Oの溶解度が15〜19％に高められるのであ
る。
従つて、抽出槽１内における水比即ち循環液／
スラグ比は、スラグ中のNa2O含有率が25〜45％
であることから、約1.5〜４でよく、このように
小さい水比により、十分に抽出を行なうことがで
きる。このように、抽出槽１における抽出液のPH
を10.5〜11.5に管理することによつて、Na2Oの溶
解度は大となり、かつ過性を悪化させるSiO2
の溶出も抑制される。
上記した抽出槽１内における抽出液のPH制御
は、抽出槽１内にCO2を含むガスを供給すること
により行なわれる。このようなCO2を含むガスの
供給は、抽出槽１の内底部付近に上向きに開口し
たガス供給管２′を設けると共に、液中で垂直軸
と共に回転する下面に複数の撹拌体が同心円上に
取付けられた、優れた気液接触効率と撹拌効果を
もつ気液接触装置２（例えば特許第960646号）を
使用することが好ましい。
上述したように、抽出槽１中でスラグを水比15
〜４により循環液ａ中に抽出溶解させるときは、
スラグは前述の如く不溶解残渣率が60％以上もあ
るから、抽出槽１における溶出液の不溶解残渣濃
度は約15〜30％になる。従つて、抽出槽１が通常
の円筒型撹拌槽では、抽出液の撹拌が困難とな
り、抽出作業性が悪化することになる。
そこでこの発明においては、第１図に示す如
く、シツクナー４における抽出液の上澄液を管路
６で、および／あるいは、分離機５における不溶
解残渣分離液の一部を管路７で、夫々還流液ｂ
として抽出槽１に還流させる。上記においてシツ
クナー４は、シツクナー４における抽出液の分離
機５にかかる負荷を低減する機能を有するが、必
ずしもシツクナー４によつて清澄液を得る必要は
なく、抽出液を大体固液分離の上、その上澄液を
抽出槽１に還流させ、併せて分離機にかかる負荷
の低減を図るものである。
上記により、シツクナー４および／あるいは分
離機５から抽出槽１へ環流される環流液ｂは、循
環液ａとは異つて、Na2Oが飽和した抽出能力の
殆んどない液であるから、この液が抽出槽１内に
環流されても、抽出作用は起らず、単に不溶解残
渣の濃度を下げる作用しか生じない。従つて、抽
出槽１内における水比は、見掛上、（循環液＋還
流液）／スラグ（以下、「見掛水比」と称する）
となり、この見掛水比を大に設定する程、不溶解
残渣濃度は小となつて、抽出槽１内における抽出
液の撹拌操作を円滑に行なうことが可能となる。
上記した見掛水比は、４未満では不溶解残渣濃
度を小となして抽出液の撹拌操作を円滑に行なう
効果が生じない。従つて４以上とすることが必要
である。しかし、余りに見掛水比が大になると、
抽出槽１の容積を必要以上に大きくしなければな
らないため、実用的には見掛水比は５〜６で操業
することが望ましい。
第３図には、Na2O−CO2−H2O系飽和液のPH
と比重との関係を示す一般図である。図面におい
て白丸印は液の温度が60℃の場合、黒丸印は35℃
の場合で、この第３図から明らかなように、飽和
液の比重は、そのPHを前記した10.5〜11.5に制御
するときには、約1.28〜1.35になり、このような
飽和液の比重は、Na2Oの濃度を低下と共に小さ
くなる。
従つて、この発明においては、抽出槽１内にお
ける抽出液の比重を、一定範囲に制御することに
より、抽出液のNa2O濃度を制御範囲内に保持す
るようにした。抽出液の比重制御管値を設定する
に当つては、その設定値を飽和液の比重に近ずけ
すぎると、Na抽出率の低下を招くおそれがあ
り、逆にその設定値が小さすぎると、スラグ処理
能力の低下および後工程の晶析操作の際に、Na
晶出率の低下を招くおそれが生ずる。
なお、抽出率は飽和点まで抽出した方が高いよ
うに考えられるが、飽和点では、もはやそれ以上
の抽出能力はないので、不溶解Na2Oが存在して
も、前記Na2Oは抽出されることなく不溶解残渣
中に入り、かえつてNa抽出率は低下する。従つ
て、工業的には上記のようなおそれのある飽和点
で制御すること不適当である。従つて、抽出液の
比重は1.25±0.02に管理し、この範囲に入るよう
に制御することが望ましい。アルカリ金属の回収
歩留を高めるためには、上述のように、該PHにお
ける制御比重値を飽和比重未満とすることが必要
である。
このような抽出液の比重を制御する手段として
は、抽出槽１内へ供給するスラグの供給量、ある
いは、循環液ａ（比重約1.06〜1.1）の量を制御
することにより行なうことができる。なお循環液
ａの量で制御する方法は、その操作性に優れてい
ることから望ましい手段である。
上述したように、この発明方法によれば、被抽
出液の見掛水比が高いことによつて、抽出槽にお
ける不溶解残渣濃度は低減され、通常の円筒型撹
拌槽でも円滑な撹拌操作が可能となり、かつ実際
に抽出能力をもつ循環液の水比は低いことによつ
て、晶析工程の前段階における蒸発濃縮工程を必
要とせず、抽出液のアルカリ金属濃度は常に一定
値に保持されているから、アルカリ金属の回収率
は高められ、これらによつて、効率的なアルカリ
金属の抽出を行なうことができる。
上記のように、アルカリ金属の回収率が高めら
れる理由は、次の通りである。即ち、抽出液の
Na2O濃度を飽和点までもつていくと、前述した
ようにスラグ中に不溶解Na2Oが残存していても
前記Na2Oは抽出されないためにかえつてNa2Oの
回収歩留は低下する。従つて、PH10.5〜11.5に対
応するNa2O飽和液の比重1.28〜1.35よりも低い
1.25±0.02に管理すれば、循環液の抽出能力が常
に残された状態となるので、上述したスラグ中に
残存するNa2Oを抽出することができ、従つて、
Na2Oの回収歩留が高まるのである。
次に実施例について説明する。
第１図に示したスラグ処理能力が約５Kg／Hr
の連続抽出物試験装置により、下記第１表に示す
成分組成のスラグを用いて抽出試験を行なつた。
なお、抽出槽には通常の円筒型撹拌槽（有効容量
30）に特許第960646号に基づく気液接触装置を
設けたものを使用した。
The present invention relates to a method for treating refining slag containing an alkali metal compound, in which alkali metals are recovered from slag produced when hot metal is subjected to desulfurization and/or dephosphorization refining using an alkali metal compound. be. Hot metal generally has a C:3.5 to 4.8 as its component.
%, Si: 0.2-1.0%, S: 0.02-0.05%, P: 0.1
However, in recent years, as the usage conditions for steel materials have become more severe, the refining ratio of high-grade steel has increased, and impurities such as S and P contained in the components have been removed as much as possible. is required to be lower than that. Normally, during refining using the oxygen steelmaking method, a slag-forming agent whose main component is quicklime is used to desulfurize and dephosphorize hot metal. The above requirements cannot be met. Therefore, before refining using the oxygen steelmaking process, hot metal is subjected to preliminary desulfurization treatment outside the furnace using sodium carbonate or carbide, but even with such preliminary desulfurization treatment, the above-mentioned It cannot be said that it is sufficient to meet the requirements. In order to enhance the desulfurization and dephosphorization effects of the hot metal mentioned above, there is a method of smelting using an alkali metal compound, such as sodium carbonate (soda ash), as a slag-forming agent that has a stronger binding force with phosphorus and sulfur than quicklime. , US Patent No. 2147205, UK Patent No. 782192
It is known by the number etc. According to this method, phosphorus and sulfur in hot metal can be reduced almost as desired. However, this method has had many problems in practical application industrially, such as the high cost of sodium carbonate, which is about four times as expensive as quicklime, and the consumption rate is large. As a means to solve the above problem, recently, hot metal is pre-smelted using a slag-forming agent mainly composed of alkali metal compounds, and impurities such as phosphorus and sulfur are removed, and the slag generated by this smelting is removed. , recovering alkali metals as carbonate-containing salts,
A method of reusing this as a slag-forming agent during refining has been researched and developed, and many patents including JP-A-52-122214 and JP-A-53-102213 have been filed. In this method, the slag produced when pre-smelting hot metal using a slag-forming agent containing an alkali metal compound as a main component, for example, contains Na: 10 to 60%,
It has a composition of Si: 1 to 15%, P: 0.5 to 22%, and S: 0.1 to 2%, and is water-soluble. The method involves dissolving Na 2 O in a solution containing Na 2 O as the main component, applying chemical treatment to this aqueous solution to extract Na 2 O, and recovering it. However, when slag is dissolved in water using this method, the undissolved residue mainly composed of oxides such as Fe, Mn, and Si contained in the slag is The residual ratio (referred to as "residue ratio") can be as high as 30 to 50%, and depending on the composition of the slag, it can be as high as 60% or more. A slag solution with a large proportion of undissolved residue has a high water-slag ratio (hereinafter referred to as "water ratio").
If it is relatively large (approximately 5 or more), an ordinary cylindrical stirring tank can be used for extraction, but in order to efficiently perform the subsequent crystallization process of sodium carbonate-containing salts, However, in the pre-stage of the crystallization process, an evaporation and concentration process is required to increase the concentration of Na, which poses a problem in that the cost of recovering soda becomes high. On the other hand, when the water ratio is as small as 4 or less, the concentration of Na 2 O in the extract becomes high, so the evaporation concentration step is not necessary and the soda recovery cost does not become high. ,
As a result of the increased concentration of undissolved residue and viscosity of the extract, stirring in the extraction process became difficult, resulting in a problem that the stirring operability of the extraction tank deteriorated. Additionally, a method is known in which the water ratio is set to 1.5 to 3.5 and extraction is performed using a spiral blade feeding type extraction device (for example, Japanese Patent Application Laid-open No. 100999/1983). As a result, it becomes necessary to carry out multi-stage extraction by setting up multiple extraction devices in series, leading to an increase in equipment cost and equipment area. Furthermore, in the conventional method, slag is simply dissolved in water, so Na 2 O in slag is dissolved by NaOH in water.
It is extracted in the form of Since 1 mol of NaOH is 40 g, if 40 g of slag is dissolved in 1 water (that is, about 3% as Na 2 O), the pH will be 14.4 g (that is, about 0.3% as Na 2 O), and the pH will be 13. Conversely,
Even if extracted at pH 13-14, Na 2 O will only be 0.3-3%. Since the pH is 13 to 14 in this way, the impurity SiO 2 is present in the solution together with Na 2 O.
About 30-50% of the amount is eluted. As a result, there was a problem that the viscosity of the solution increased and the transient nature of the undissolved residue deteriorated significantly. Further, the Na 2 O content in the slag is not constant, and varies, for example, within 25% to 45%. the result,
Fluctuations occur in the Na 2 O concentration in the solution, but because such fluctuations in Na 2 O concentration have not been managed in the past, the recovery yield of Na 2 O is poor and various problems arise from the operational perspective of the process. There were negative effects. From the above-mentioned viewpoint, the present invention provides a method for extracting alkali metals from slag produced during smelting of hot metal using a slag-forming agent containing an alkali metal compound as a main component. Eliminates the need for the evaporation concentration step of the extract in the preceding stage, improves stirring operability in the extraction process, lowers the concentration of undissolved residue in the extract, and maintains the alkali metal concentration of the extract within a certain range. The present invention provides a method for treating slag containing alkali metal compounds, which increases the recovery yield of alkali metals and enables efficient extraction of alkali metals. Slag produced during refining using a compound is dissolved in an extracted liquid consisting of a mixture of Na 2 O - CO 2 - H 2 O system circulating liquid and reflux liquid in an extraction tank. In a method for treating refining slag containing an alkali metal compound in which alkali metals are recovered from an extract, the ratio of the circulating liquid to the slag in the extraction tank is reduced, and a thickener for the extract is added to the extraction tank. The upper liquid and/or a part of the undissolved residue separated liquid of the extract is refluxed as a reflux liquid so that the ratio of the extract to the slag in the extraction tank is 4 or more, and the extract is The alkali metal concentration in the extract is maintained at a constant value by controlling the specific gravity to be less than the saturated specific gravity and controlling the pH by blowing carbon dioxide into the extraction tank. It is something. Next, this invention will be explained with reference to the drawings. FIG. 1 shows a system diagram of an example of the method of the invention. In the drawing, 1 is an extraction tank consisting of a normal cylindrical stirring tank, 2 is a gas-liquid contact device provided in the extraction tank 1, 3 is a pump provided on the outlet side of the extraction tank 1, 4 is a thickener, and 5 is a thickener. is a separator. The slag produced when hot metal is treated using a slag-forming agent containing an alkali metal compound as its main component is crushed in advance to a diameter of 20 mm or less using an ordinary crusher in order to improve extraction workability. is 10mmφ
After pulverizing and grading as follows, table feeder,
The powder is supplied to the extraction tank 1 using a conventional powder supply device (not shown) such as a rotary feeder. The liquid to be extracted for extracting the components contained in the slag in extraction tank 1 is a separated liquid that is recovered by crystallizing Na as bicarbonate at a relatively low temperature of 60°C or less in the subsequent crystallization process. , Na2O
- A mixed liquid of a circulating liquid (hereinafter referred to as "circulating liquid") a of a -CO 2 - H 2 O-based saturated liquid and a reflux liquid b that is refluxed from the thickener 4 and/or the separator 5 to the extraction tank 1 is used. . Generally, in order to crystallize and recover Na in slag as bicarbonate, it is necessary to
It is necessary to control it to 9.5 or less, preferably 9 or less. Therefore, the pH of the circulating liquid a sent into the extraction tank 1 is naturally 9.5 or less, or 9 or less. Therefore, the present inventors investigated the relationship between the pH of the Na 2 O-CO 2 -H 2 O system saturated solution and the Na 2 O solubility in the solution, and found that there is a relationship as shown in Figure 2. I found out. That is, Fig. 2 shows Na 2 O−CO 2
FIG. 2 is a general diagram showing a solubility curve of Na 2 O in relation to the pH of a -H 2 O--based saturated liquid. In the drawing,
White circles indicate when the liquid temperature is 60°C, and black circles indicate when the liquid temperature is 35°C. As shown in the drawing, the pH of the liquid
is less than 9.5, the solubility of Na 2 O in the liquid is 4~
5.5%, whereas when the pH of the liquid is 10.5 or higher, the solubility of Na 2 O in the liquid increases to 15-19%. Note that the above-mentioned solubility refers to the extraction ability of the liquid, and does not mean that the liquid can be extracted to saturation. Therefore, the pH of the extract in the extraction tank 1 is controlled to 10.5 to 11.5, thereby increasing the Na 2 O solubility of the circulating fluid a to 15 to 11.5.
It can be increased to 19%. That is, the dissolving power of the circulating fluid a corresponds to the difference between the solubility of Na 2 O at pH 10.5 to 11.5 and the solubility of Na 2 O at pH 9.5 or lower. In other words, it is (15-19%) - (4-5.5%), and has a Na 2 O dissolving ability of about 10-15%, which is higher than the conventional 0.3-3%. Such dissolution of Na 2 O into the circulating liquid a is carried out using a gas-liquid contact device 2 as shown in FIG.
Since the extraction is carried out while blowing carbon dioxide gas through the gas supply pipe 2', the extraction liquid in the extraction tank 1 is Na 2 O-
CO 2 −H 2 O system More specifically, Na 2 CO 3 −NaHCO 3
−H 2 O system is formed. Therefore, at PH10.5-11.5,
The solubility of Na 2 O is increased to 15-19%. Therefore, the water ratio in the extraction tank 1, that is, the circulating liquid/
Slag ratio is Na2O content in slag 25-45%
Therefore, the water ratio may be approximately 1.5 to 4, and sufficient extraction can be achieved with such a small water ratio. In this way, the pH of the extract in extraction tank 1 is
By controlling the solubility of Na 2 O to 10.5 to 11.5, the solubility of Na 2 O increases and SiO 2
The elution of is also suppressed. The pH control of the extract in the extraction tank 1 described above is performed by supplying gas containing CO 2 into the extraction tank 1. In order to supply such a gas containing CO 2 , a gas supply pipe 2' that opens upward is provided near the inner bottom of the extraction tank 1, and a plurality of agitators are arranged concentrically on the lower surface of the liquid that rotates with a vertical axis. It is preferable to use a gas-liquid contact device 2 (for example, Patent No. 960646), which is attached to a gas-liquid contact device 2 and has excellent gas-liquid contact efficiency and stirring effect. As mentioned above, in the extraction tank 1, the slag to water ratio was 15
When extracting and dissolving in the circulating fluid a by 4.
Since the slag has an undissolved residue rate of 60% or more as described above, the undissolved residue concentration of the eluate in the extraction tank 1 is about 15 to 30%. Therefore, if the extraction tank 1 is a normal cylindrical stirring tank, it will be difficult to stir the extract, and the extraction workability will deteriorate. Therefore, in the present invention, as shown in FIG. Reflux liquid b
It is refluxed to extraction tank 1 as In the above, the thickener 4 has a function of reducing the load on the extract liquid separator 5 in the thickener 4, but it is not necessarily necessary to obtain a clear liquid by the thickener 4. The supernatant liquid is refluxed to the extraction tank 1, thereby reducing the load on the separator. Due to the above, the reflux liquid b that is recycled from the thickener 4 and/or the separator 5 to the extraction tank 1 is a liquid that is saturated with Na 2 O and has almost no extraction ability, unlike the circulating liquid a. Even if this liquid is refluxed into the extraction tank 1, no extraction action occurs, and only the action of lowering the concentration of undissolved residue occurs. Therefore, the apparent water ratio in the extraction tank 1 is (circulating liquid + reflux liquid)/slag (hereinafter referred to as "apparent water ratio").
Therefore, the higher the apparent water ratio is set, the lower the undissolved residue concentration becomes, and the smoother the stirring operation of the extract in the extraction tank 1 becomes. If the above-mentioned apparent water ratio is less than 4, the effect of reducing the concentration of undissolved residue and smoothly performing the stirring operation of the extract will not be produced. Therefore, it is necessary to set it to 4 or more. However, if the apparent water ratio becomes too large,
Since the volume of the extraction tank 1 must be made larger than necessary, it is practically desirable to operate with an apparent water ratio of 5 to 6. Figure 3 shows the pH of the Na 2 O−CO 2 −H 2 O system saturated liquid.
It is a general diagram showing the relationship between and specific gravity. In the drawing, the white circle indicates that the liquid temperature is 60℃, and the black circle indicates that the temperature is 35℃.
In the case of 2 It decreases as the O concentration decreases. Therefore, in the present invention, the specific gravity of the extract in the extraction tank 1 is controlled within a certain range, thereby maintaining the Na 2 O concentration of the extract within the controlled range. When setting the specific gravity control tube value for the extract liquid, if the set value is too close to the specific gravity of the saturated liquid, the Na extraction rate may decrease, and conversely, if the set value is too small, , a decrease in slag processing capacity and during crystallization operations in the post-process.
This may lead to a decrease in crystallization rate. It is thought that the extraction rate is higher when extracted up to the saturation point, but at the saturation point there is no longer any extraction ability, so even if insoluble Na 2 O is present, the Na 2 O cannot be extracted. It enters the undissolved residue without being absorbed, and the Na extraction rate decreases on the contrary. Therefore, industrially, it is inappropriate to control at the saturation point where there is a risk of the above. Therefore, it is desirable to control the specific gravity of the extract to 1.25±0.02 and to keep it within this range. In order to increase the recovery yield of alkali metals, as mentioned above, it is necessary to set the control specific gravity value at the PH to less than the saturated specific gravity. The specific gravity of the extract can be controlled by controlling the amount of slag supplied into the extraction tank 1 or the amount of circulating liquid a (specific gravity of about 1.06 to 1.1). Note that the method of controlling by the amount of circulating fluid a is a desirable method because of its excellent operability. As described above, according to the method of the present invention, the concentration of undissolved residue in the extraction tank is reduced due to the high apparent water ratio of the liquid to be extracted, and smooth stirring operation can be achieved even in a normal cylindrical stirring tank. Because the water ratio of the circulating fluid that actually has the extraction ability is low, there is no need for an evaporative concentration step before the crystallization step, and the alkali metal concentration of the extract is always maintained at a constant value. Therefore, the recovery rate of the alkali metal is increased, and the alkali metal can be extracted efficiently. The reason why the alkali metal recovery rate is increased as described above is as follows. That is, the extract
When the Na 2 O concentration is brought to the saturation point, as mentioned above, even if undissolved Na 2 O remains in the slag, the Na 2 O is not extracted, so the recovery yield of Na 2 O decreases. descend. Therefore, the specific gravity of the Na 2 O saturated liquid, which corresponds to PH 10.5-11.5, is lower than 1.28-1.35.
If it is controlled at 1.25±0.02, the extraction capacity of the circulating fluid will always remain, so the Na 2 O remaining in the slag described above can be extracted, and therefore,
This increases the recovery yield of Na 2 O. Next, an example will be described. The slag processing capacity shown in Figure 1 is approximately 5Kg/Hr.
An extraction test was conducted using a continuous extract test device using slag having the composition shown in Table 1 below.
The extraction tank is a regular cylindrical stirring tank (effective capacity
30) equipped with a gas-liquid contact device based on Patent No. 960646 was used.
【表】
抽出条件
スラグ供給量 ５Kg／Hr
スラグ粒度 ３mm
水比（循環液／スラグ） ３（循環液量15
Kg／Hr）
見掛水比〔（循環液＋還流液）／スラグ〕
５（還流液量10Kg／Hr）
循環液PH ９
PH調整ガス CO2：20％、O2：８％、N2：
72％の合成ガス
抽出液温度 50±50℃
抽出液比重 1.25±0.02
抽出液PH 10.5〜11.5
抽出槽滞留時間 60分
上記条件により試験を行なつた結果、抽出液の
Na2O濃度を、常に14±１％に管理することがで
きた。このときスラグの供給量は、５±0.5Kg／
Hrであり、スラグのNa2O含有率に変動があつて
も抽出液のNa2O濃度を常に一定範囲内に管理す
ることができた。次に、この試験結果を示す。
Na2O抽出率 94％
不純物溶出率SiO2 4.7％、P2O5 89％、Ｓ
65％
不溶解残渣の過特性値 25.1Wet Cake
Kg／m2・Hr
以上述べたように、この発明によれば、アルカ
リ金属化合物を主成分とする造滓剤を使用して溶
銑の予備精錬を行なう際に生成するスラグよりア
ルカリ金属を抽出するに当り、晶析工程の前段階
における抽出液の蒸発濃縮工程を不要にし、しか
も抽出工程における撹拌操作性を良好となし、抽
出液中の不溶解残渣濃度を低め、スラグ中のアル
カリ金属含有率に変動があつても抽出液のアルカ
リ金属濃度は常に一定値に保持され、これらによ
つて効率的なアルカリ金属の抽出を行なうことが
できる等、工業上優れた効果がもたらされる。[Table] Extraction conditions Slag supply amount 5Kg/Hr Slag particle size 3mm Water ratio (circulating fluid/slag) 3 (circulating fluid amount 15
Kg/Hr) Apparent water ratio [(circulating fluid + reflux fluid)/slag]
5 (reflux liquid amount 10Kg/Hr) Circulating fluid PH 9 PH adjustment gas CO 2 : 20%, O 2 : 8%, N 2 :
72% synthesis gas Extract temperature 50±50℃ Extract specific gravity 1.25±0.02 Extract PH 10.5-11.5 Residence time in extraction tank 60 minutes As a result of testing under the above conditions,
The Na 2 O concentration could always be controlled at 14±1%. At this time, the amount of slag supplied is 5±0.5Kg/
Hr, and even if the Na 2 O content of the slag varied, the Na 2 O concentration of the extract could always be controlled within a certain range. Next, the test results are shown. Na 2 O extraction rate 94% Impurity elution rate SiO 2 4.7%, P 2 O 5 89%, S
65% Overcharacteristic value of undissolved residue 25.1Wet Cake
Kg/m 2・Hr As described above, according to the present invention, alkali metals are extracted from the slag produced when hot metal is pre-smelted using a slag-forming agent whose main component is an alkali metal compound. This eliminates the need for the evaporation concentration step of the extract in the pre-crystallization step, improves stirring operability in the extraction step, lowers the concentration of undissolved residue in the extract, and reduces the alkali metal content in the slag. The alkali metal concentration of the extract is always maintained at a constant value even if there are fluctuations in the alkali metal concentration, and this brings about excellent industrial effects such as efficient alkali metal extraction.
第１図はこの発明方法の一例を示す系統図、第
２図はNa2O−CO2−H2O系飽和液のPHとの関係
におけるNa2O溶解度曲線を示す一般図、第３図
はNa2O−CO2−H2O系飽和液のPHとの比重との
関係を示す一般図である。
図面において、１……抽出槽、２……気液接触
装置、３……ポンプ、４……シツクナー、５……
分離機、６，７……管路。
Fig. 1 is a system diagram showing an example of the method of this invention, Fig. 2 is a general diagram showing the Na 2 O solubility curve in relation to the pH of a Na 2 O - CO 2 - H 2 O system saturated liquid, and Fig. 3 is a general diagram showing the relationship between the pH and specific gravity of a Na 2 O-CO 2 -H 2 O-based saturated liquid. In the drawings, 1... extraction tank, 2... gas-liquid contact device, 3... pump, 4... thickener, 5...
Separator, 6, 7...pipe line.
Claims (1)
る際に生成するスラグを、抽出槽において、
Na2O−CO2−H2O系の循環液と還流液の混合液
からなる被抽出液中に溶解させて得た抽出液から
アルカリ金属を回収するアルカリ金属化合物を含
有する精錬スラグの処理方法において、 前記抽出槽における、前記循環液のスラグに対
する比を小にした上、前記抽出槽中に、前記抽出
液のシツクナーにおける上澄液、および／あるい
は、前記抽出液の不溶解残渣分離液の一部を還
流液として還流して、前記抽出槽における前記抽
出液のスラグに対する比を４以上になすと共に、
前記抽出液の比重を飽和比重未満に制御し、且
つ、前記抽出槽中への炭酸ガスの吹込みによりPH
を制御することにより、前記抽出液中のアルカリ
金属濃度を一定値に保持することを特徴とするア
ルカリ金属化合物を含有する精錬スラグの処理方
法。[Claims] 1. Slag produced when hot metal is refined using an alkali metal compound, in an extraction tank,
Processing of refining slag containing alkali metal compounds, in which alkali metals are recovered from the extracted liquid obtained by dissolving them in a liquid to be extracted consisting of a mixed liquid of circulating liquid and reflux liquid in the Na 2 O－CO 2 -H 2 O system. In the method, the ratio of the circulating liquid to slag in the extraction tank is reduced, and a supernatant liquid of the extract in a thickener and/or a separated liquid of undissolved residue of the extract is added to the extraction tank. Refluxing a part of the liquid as a reflux liquid to make the ratio of the extract liquid to slag in the extraction tank 4 or more,
The specific gravity of the extract is controlled to be less than the saturated specific gravity, and the pH is lowered by blowing carbon dioxide into the extraction tank.
A method for treating refining slag containing an alkali metal compound, characterized in that the alkali metal concentration in the extract is maintained at a constant value by controlling.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11867980A JPS5742530A (en) | 1980-08-28 | 1980-08-28 | Treatment of smelting slag containing alkali metal compound |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11867980A JPS5742530A (en) | 1980-08-28 | 1980-08-28 | Treatment of smelting slag containing alkali metal compound |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5742530A JPS5742530A (en) | 1982-03-10 |
| JPS6235966B2 true JPS6235966B2 (en) | 1987-08-05 |
Family
ID=14742514
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11867980A Granted JPS5742530A (en) | 1980-08-28 | 1980-08-28 | Treatment of smelting slag containing alkali metal compound |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5742530A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0437133U (en) * | 1990-07-27 | 1992-03-27 |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104498722A (en) * | 2014-12-16 | 2015-04-08 | 贵州重力科技环保有限公司 | Method for comprehensively recovering mercury and selenium from metallurgical slag |
-
1980
- 1980-08-28 JP JP11867980A patent/JPS5742530A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0437133U (en) * | 1990-07-27 | 1992-03-27 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5742530A (en) | 1982-03-10 |
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