JP5667374B2 - Method for recovering phosphoric acid from steelmaking slag - Google Patents
Method for recovering phosphoric acid from steelmaking slag Download PDFInfo
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- JP5667374B2 JP5667374B2 JP2010084919A JP2010084919A JP5667374B2 JP 5667374 B2 JP5667374 B2 JP 5667374B2 JP 2010084919 A JP2010084919 A JP 2010084919A JP 2010084919 A JP2010084919 A JP 2010084919A JP 5667374 B2 JP5667374 B2 JP 5667374B2
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- steelmaking slag
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- sulfuric acid
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- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 title claims description 154
- 229910000147 aluminium phosphate Inorganic materials 0.000 title claims description 77
- 239000002893 slag Substances 0.000 title claims description 75
- 238000009628 steelmaking Methods 0.000 title claims description 62
- 238000000034 method Methods 0.000 title claims description 24
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 86
- 239000011574 phosphorus Substances 0.000 claims description 46
- 229910052698 phosphorus Inorganic materials 0.000 claims description 46
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 45
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 24
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 19
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 16
- 238000000605 extraction Methods 0.000 claims description 14
- 238000011084 recovery Methods 0.000 claims description 9
- 238000010828 elution Methods 0.000 claims description 8
- 229910052742 iron Inorganic materials 0.000 claims description 8
- 238000001704 evaporation Methods 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- 239000003960 organic solvent Substances 0.000 description 23
- 229910019142 PO4 Inorganic materials 0.000 description 15
- 239000010452 phosphate Substances 0.000 description 15
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 15
- 239000002253 acid Substances 0.000 description 10
- 239000002904 solvent Substances 0.000 description 9
- 239000000047 product Substances 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 7
- 239000011575 calcium Substances 0.000 description 7
- 229910052791 calcium Inorganic materials 0.000 description 7
- 229910052500 inorganic mineral Inorganic materials 0.000 description 7
- 239000011707 mineral Substances 0.000 description 7
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 6
- 239000007788 liquid Substances 0.000 description 6
- 239000003795 chemical substances by application Substances 0.000 description 5
- 239000003337 fertilizer Substances 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 4
- 238000004821 distillation Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- LWIHDJKSTIGBAC-UHFFFAOYSA-K tripotassium phosphate Chemical compound [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 description 4
- 229910001341 Crude steel Inorganic materials 0.000 description 3
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 241000287828 Gallus gallus Species 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 229910000805 Pig iron Inorganic materials 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 2
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 description 2
- 238000006477 desulfuration reaction Methods 0.000 description 2
- 230000023556 desulfurization Effects 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 239000010436 fluorite Substances 0.000 description 2
- BHEPBYXIRTUNPN-UHFFFAOYSA-N hydridophosphorus(.) (triplet) Chemical compound [PH] BHEPBYXIRTUNPN-UHFFFAOYSA-N 0.000 description 2
- ZXEKIIBDNHEJCQ-UHFFFAOYSA-N isobutanol Chemical compound CC(C)CO ZXEKIIBDNHEJCQ-UHFFFAOYSA-N 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 229910001392 phosphorus oxide Inorganic materials 0.000 description 2
- 229910000160 potassium phosphate Inorganic materials 0.000 description 2
- 235000011009 potassium phosphates Nutrition 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 150000003138 primary alcohols Chemical class 0.000 description 2
- -1 sulfuric acid Chemical class 0.000 description 2
- VSAISIQCTGDGPU-UHFFFAOYSA-N tetraphosphorus hexaoxide Chemical compound O1P(O2)OP3OP1OP2O3 VSAISIQCTGDGPU-UHFFFAOYSA-N 0.000 description 2
- 230000008016 vaporization Effects 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 239000004480 active ingredient Substances 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004993 emission spectroscopy Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 210000003608 fece Anatomy 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000010871 livestock manure Substances 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- IZGYIFFQBZWOLJ-CKAACLRMSA-N phaseic acid Chemical compound C1C(=O)C[C@@]2(C)OC[C@]1(C)[C@@]2(O)C=CC(/C)=C\C(O)=O IZGYIFFQBZWOLJ-CKAACLRMSA-N 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 150000003112 potassium compounds Chemical class 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000000935 solvent evaporation Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000007738 vacuum evaporation Methods 0.000 description 1
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- Processing Of Solid Wastes (AREA)
Description
本発明は、製鉄所等で発生する溶銑予備処理スラグ、転炉スラグ等の製鋼スラグに含まれるリン成分を、効率よく遊離リン酸として回収する方法に関する。 The present invention relates to a method for efficiently recovering phosphorus components contained in steelmaking slag such as hot metal pretreatment slag and converter slag generated at steelworks and the like as free phosphoric acid.
高炉で製造された溶銑やスクラップから、靱性及び 加工性のある鋼にするのが製鋼工程であり、製鋼炉には転炉、電気炉がある。製銑工程では、鉄鉱石にコークスや造滓剤を加えて高炉で加熱し、銑鉄を生産する。銑鉄は、溶銑予備処理として造滓剤を加えて加熱され、脱リン及び脱硫された後、さらに造滓剤を加えて転炉で加熱され、粗鋼へと変化する。 The steelmaking process is to make tough and workable steel from hot metal and scrap produced in a blast furnace, and there are converters and electric furnaces. In the iron making process, iron ore is added with coke and iron making agent and heated in a blast furnace to produce pig iron. Pig iron is heated by adding a iron making agent as a hot metal pretreatment, and after dephosphorization and desulfurization, it is further heated by a converter with the addition of a iron making agent and converted into crude steel.
溶銑予備処理及び転炉からは、脱リン・脱硫スラグ及び転炉スラグが生成されるが、これらは製鋼スラグと呼ばれる。一般的には、粗鋼1ｔ当たり約110kgの製鋼スラグが生成するといわれている。 From the hot metal pretreatment and the converter, dephosphorization / desulfurization slag and converter slag are produced, which are called steelmaking slag. Generally, it is said that about 110 kg of steelmaking slag is produced per ton of crude steel.
製鋼スラグは、粗鋼の生産において大量に発生するため、その有効利用に注目されている。例えば、製鋼スラグを冷却した後に、磁力により磁着物と非磁着物とに分離して回収し、次いで、該非磁着物に還元剤を混合し、混合した後に加熱処理して、非磁着物に含有されるリン酸化物を還元して気化除去し、リン酸化物を気化除去した後の非磁着物及び前記磁着物を、製銑工程又は製鋼工程にリサイクルする方法が、特許文献１に開示されている。 Since steelmaking slag is generated in large quantities in the production of crude steel, attention is paid to its effective use. For example, after steelmaking slag is cooled, it is separated and collected into a magnetic product and a non-magnetic product by magnetic force, then a reducing agent is mixed in the non-magnetic product, mixed and then heat-treated, and contained in the non-magnetic product. Patent Document 1 discloses a method for reducing and vaporizing and removing the phosphorus oxide, and recycling the non-magnetized product and the magnetized product after vaporizing and removing the phosphorus oxide to a steelmaking process or a steelmaking process. Yes.
また、低リン転炉スラグを脱リン炉において造滓剤として再利用するに当り、ホタル石の使用量及び遺失量の減少を図るために、前記転炉から排滓される転炉スラグを滓鍋で受滓する際、予め前記滓鍋中に少なくともホタル石等の副材を装入した状態で前記転炉スラグを受滓し、前記副材を転炉スラグ中に溶融・混合した後、脱リン炉又は取鍋における脱リン処理に供することが、特許文献２に開示されている。 In order to reduce the amount of fluorite used and lost when reusing low-phosphorus converter slag as a shaping agent in a dephosphorization furnace, the converter slag discharged from the converter is reduced. When receiving in a pot, after receiving the converter slag in a state where at least a secondary material such as fluorite is charged in advance in the pot, after melting and mixing the secondary material in the converter slag, It is disclosed in Patent Document 2 to be subjected to a dephosphorization process in a dephosphorization furnace or a ladle.
また、溶融鉄の精錬に再利用するに際し、復リンが生じない転炉スラグの利用方法として、転炉スラグのリン濃度を溶銑や溶鋼のリン濃度などから予め推定し、該推定値に応じて転炉スラグを分別回収し、溶鋼のリン濃度に適合するリン濃度の分別回収物を、造滓剤として選択使用する転炉滓の利用方法が、特許文献３に開示されている。 In addition, as a method of using converter slag that does not cause recovery phosphorus when reusing it for refining molten iron, the phosphorus concentration in the converter slag is estimated in advance from the hot metal, the phosphorus concentration in the molten steel, etc., and according to the estimated value Patent Document 3 discloses a method for using a converter slag that collects and recovers converter slag and selectively uses a phosphorus concentration fraction recovered that matches the phosphorus concentration of the molten steel as a slagging agent.
製鋼スラグから回収されるリンを肥料として有効利用することにも注目されている。例えば、鶏糞焼却灰に対し、塩基性カリウム化合物粉末又は高炉水砕スラグ粉末より選ばれる１種以上を混合し、これに鉱酸を添加し、反応させて得られる新規リン酸カリ複合肥料であって、前記鶏糞焼却灰に含まれる難溶性リン酸塩が実質的に有効成分に変換されているとともにカリウム及び／又はケイ酸を多く含むことを特徴とする新規リン酸カリ複合肥料が、特許文献４に開示されている。 Attention has also been paid to the effective use of phosphorus recovered from steelmaking slag as fertilizer. For example, it is a novel potassium phosphate complex fertilizer obtained by mixing one or more selected from basic potassium compound powder or ground granulated blast furnace slag powder with chicken acid incineration ash, adding mineral acid to this, and reacting. A novel potassium phosphate complex fertilizer characterized in that the hardly soluble phosphate contained in the chicken manure incineration ash is substantially converted into an active ingredient and contains a large amount of potassium and / or silicic acid. 4.
一方、遊離リン酸の工業的生産方法としては、図２に示すように、リン鉱石と硫酸とを反応させ、リン鉱石から遊離リン酸を抽出する湿式リン酸法が知られている（非特許文献１）。 On the other hand, as an industrial production method of free phosphoric acid, as shown in FIG. 2, a wet phosphoric acid method is known in which phosphorus ore and sulfuric acid are reacted to extract free phosphoric acid from the phosphate ore (non-patent). Reference 1).
非特許文献１に記載されている遊離リン酸製造方法を製鋼スラグに適用することが考えられるが、製鋼スラグと硫酸等の鉱酸を反応させる際に、鉱酸濃度が低いとリン成分の抽出効率が低い。 It is conceivable to apply the free phosphoric acid production method described in Non-Patent Document 1 to steelmaking slag, but when reacting steelmaking slag with mineral acids such as sulfuric acid, if the mineral acid concentration is low, extraction of phosphorus components Low efficiency.
製鋼スラグと高濃度の鉱酸とを反応させ、その後鉱酸に水を添加することにより、リン成分の抽出効率を向上させることも可能であるが、回収液中のリン酸濃度が低くなるため、濃縮にコストがかかることになる。また、リン成分を付加価値の低いリン酸塩としてしか回収できないという制限も存在する。
また、非特許文献１に開示されている遊離リン酸製造方法は、リン鉱石中のリン含有量が 5〜40重量％であるのに対し、製鋼スラグのリン含有量が3〜5重量％と低いため、そのまま製鋼スラグに適用しても、抽出される遊離リン酸量が少ないため、リン成分を抽出した製鋼スラグと、抽出した遊離リン酸とを固液分離することも困難である。
It is possible to improve the extraction efficiency of the phosphorus component by reacting steelmaking slag with a high concentration of mineral acid and then adding water to the mineral acid, but the concentration of phosphoric acid in the recovered liquid will be low Concentration will be costly. There is also a limitation that the phosphorus component can only be recovered as a phosphate with low added value.
Further, in the method for producing free phosphoric acid disclosed in Non-Patent Document 1, the phosphorus content in the phosphate ore is 5 to 40% by weight, whereas the phosphorus content in the steelmaking slag is 3 to 5% by weight. Even if it is applied to steelmaking slag as it is, it is difficult to solid-liquid separate the steelmaking slag from which the phosphorus component is extracted and the extracted free phosphoric acid because the amount of free phosphoric acid extracted is small.
さらに、製鋼スラグから回収したリン成分を肥料とする場合であっても、リン成分含有量が低いためにリン肥料規格を満たさない場合もあった。製鋼スラグからのリン成分の回収を工業的に行う場合、処理コストよりも付加価値の高いリン製品として回収することが重要となる。そのためにはリン成分をリン酸塩ではなく、遊離リン酸として回収することが好ましい。 Furthermore, even when the phosphorus component recovered from the steelmaking slag is used as a fertilizer, the phosphorus fertilizer standard may not be satisfied because the phosphorus component content is low. When industrially recovering the phosphorus component from the steelmaking slag, it is important to recover it as a phosphorus product having a higher added value than the processing cost. For this purpose, it is preferable to recover the phosphorus component as free phosphoric acid instead of phosphate.
本発明は、リン鉱石と比較してリン含有量の少ない製鋼スラグから、効率よく遊離リン酸を回収するための方法の提供を目的とする。 An object of the present invention is to provide a method for efficiently recovering free phosphoric acid from a steelmaking slag having a low phosphorus content compared to phosphorus ore.
本発明者は、製鋼スラグと硫酸とを反応させ、遊離リン酸を溶出させた後、有機溶媒を用いて遊離リン酸を抽出すれば、製鋼スラグと遊離リン酸との固液分離が容易となり、遊離リン酸の濃度を低下させることなく回収可能であることを見出し、本発明を完成させるに至った。 The inventor makes steelmaking slag and sulfuric acid react to elute free phosphoric acid, and then the free phosphoric acid is extracted using an organic solvent, which facilitates solid-liquid separation of the steelmaking slag and free phosphoric acid. The present inventors have found that it can be recovered without reducing the concentration of free phosphoric acid, and have completed the present invention.
具体的に、本発明は、
製鋼スラグと硫酸とを反応させ、製鋼スラグに含まれるリン成分を遊離リン酸として溶出させる溶出工程と、
溶出工程後の製鋼スラグ及び硫酸の混合物から、メタノール又はエタノールを用いて遊離リン酸を抽出する抽出工程と、
メタノール又はエタノールを蒸発させ、遊離リン酸を回収する遊離リン酸回収工程と、
を有し、
硫酸の濃度が5mol/l以上であり、
前記溶出工程において、製鋼スラグ1kgに対して硫酸10mol以上15mol以下を反応させる、製鋼スラグからのリン酸回収方法に関する。
Specifically, the present invention
An elution step of reacting steelmaking slag with sulfuric acid to elute the phosphorus component contained in the steelmaking slag as free phosphoric acid;
From the steelmaking slag and sulfuric acid mixture after the elution step, an extraction step for extracting free phosphoric acid using methanol or ethanol ,
Free phosphoric acid recovery step of evaporating methanol or ethanol and recovering free phosphoric acid;
I have a,
The concentration of sulfuric acid is 5 mol / l or more,
The present invention relates to a method for recovering phosphoric acid from steelmaking slag , wherein 10 mol or more and 15 mol or less of sulfuric acid are reacted with 1 kg of steelmaking slag in the elution step .
製鋼スラグと硫酸とを混合して反応させると、製鋼スラグに含まれるリン酸塩が遊離リン酸として表面に溶出する。これに水を加えると製鋼スラグ表面に付着している遊離リン酸を回収することができるが、リン酸が水に溶解して希薄水溶液となるため、後段の濃縮工程の負荷が大きくなる。また、製鋼スラグからはカルシウム塩等も溶出するため、水を加えるとこれら塩等も溶解し、回収する遊離リン酸の純度が低下しやすい。 When steelmaking slag and sulfuric acid are mixed and reacted, the phosphate contained in the steelmaking slag is eluted on the surface as free phosphoric acid. When water is added to this, free phosphoric acid adhering to the steelmaking slag surface can be recovered, but phosphoric acid dissolves in water to form a dilute aqueous solution, which increases the load of the subsequent concentration step. Further, since calcium salts and the like are also eluted from the steelmaking slag, when water is added, these salts and the like are dissolved, and the purity of the recovered free phosphoric acid tends to be lowered.
そこで、本発明では、水ではなく有機溶媒を加えて製鋼スラグ表面の遊離リン酸を溶解させ、回収する。この場合、遊離リン酸はリン酸塩にはならず、リン酸塩以外の塩等も混入しにくいという利点がある。また、蒸留等の操作によって有機溶媒を蒸発させれば、遊離リン酸と分離することも容易である。 Therefore, in the present invention, an organic solvent, not water, is added to dissolve and recover free phosphoric acid on the steelmaking slag surface. In this case, free phosphoric acid does not become a phosphate, and there is an advantage that a salt other than the phosphate is hardly mixed. Further, if the organic solvent is evaporated by an operation such as distillation, it can be easily separated from free phosphoric acid.
なお、硫酸以外の鉱酸、例えば、硝酸又は塩酸を用いても製鋼スラグから遊離リン酸を溶出させることは可能である。このとき、硝酸カルシウム又は塩化カルシウムも同時に抽出されるが、これら塩類は遊離リン酸に対する溶解度も大きいため、回収させる遊離リン酸の純度が低下しやすい。 In addition, it is possible to elute free phosphoric acid from steelmaking slag also using mineral acids other than sulfuric acid, for example, nitric acid or hydrochloric acid. At this time, calcium nitrate or calcium chloride is also extracted at the same time, but since these salts have a high solubility in free phosphoric acid, the purity of the free phosphoric acid to be recovered tends to decrease.
しかし、本発明では硫酸を使用するため、溶解度の低い硫酸カルシウムしか生成されず、回収される遊離リン酸の純度が低下しにくい。 However, since sulfuric acid is used in the present invention, only calcium sulfate with low solubility is produced, and the purity of the recovered free phosphoric acid is unlikely to decrease.
硫酸の濃度は、5mol/l（10N）以上である。 The concentration of sulfuric acid is 5 mol / l (10N) or more .
硫酸濃度が5mol/l(10N)以下（38wt%以下）では、製鋼スラグから遊離リン酸を抽出する効果が低いためである。 This is because when the sulfuric acid concentration is 5 mol / l (10 N) or less (38 wt% or less), the effect of extracting free phosphoric acid from steelmaking slag is low.
前記溶出工程においては、製鋼スラグ1kgに対して硫酸10mol以上15mol以下を反応させる。 In the elution step, 10 mol or more and 15 mol or less of sulfuric acid are reacted with 1 kg of steelmaking slag .
製鋼スラグ1kgと反応させる硫酸が10mol未満では、製鋼スラグから遊離リン酸を溶出させることが困難である。一方、製鋼スラグ1kgと反応させる硫酸が15molを超えると、遊離リン酸に過剰の硫酸が溶解し、純度を下げることになる。 If the sulfuric acid reacted with 1 kg of steelmaking slag is less than 10 mol, it is difficult to elute free phosphoric acid from the steelmaking slag. On the other hand, when the sulfuric acid reacted with 1 kg of steelmaking slag exceeds 15 mol, excess sulfuric acid is dissolved in free phosphoric acid, and the purity is lowered.
また、15molを超える硫酸と反応させても、過剰の硫酸が有機溶媒と共に後の工程まで残存することになるため、得られる遊離リン酸の純度が低くなるおそれがある。製鋼スラグはカルシウム分を多く含有しており、添加した硫酸の内、リン酸の抽出に利用されない硫酸は全てカルシウム分と反応すると考えられていたが、実際には製鋼スラグの表面でのみカルシウム分と反応し、カルシウム分と反応しない過剰の硫酸は、そのまま残存することが判明した。 Moreover, even if it reacts with sulfuric acid exceeding 15 mol, excess sulfuric acid will remain | survive with an organic solvent until a subsequent process, and there exists a possibility that the purity of the free phosphoric acid obtained may become low. Steelmaking slag contains a large amount of calcium. Of the added sulfuric acid, it was thought that all sulfuric acid that was not used for the extraction of phosphoric acid would react with calcium, but in reality, only the surface of steelmaking slag contained calcium. It was found that excess sulfuric acid that reacts with the calcium component and does not react with the calcium content remains as it is.
本発明で使用するメタノール又はエタノールは、遊離リン酸を溶解させやすく、蒸発させることによって溶解させた遊離リン酸を容易に分離できる。 Methanol or ethanol used in the present invention is easily dissolved free phosphoric acid, Ru can be easily separated free phosphoric acid dissolved by evaporation.
前記製鋼スラグは、鉄濃縮相とリン濃縮相に分離した後のリン濃縮相のスラグであることが好ましい。 The steelmaking slag is preferably a slag of a phosphorus-enriched phase after being separated into an iron-enriched phase and a phosphorus-enriched phase.
本発明のリン回収方法は、リン濃度がより高いリン濃縮相のスラグに適用することが、リン回収効率の点からは好ましいためである。 This is because the phosphorus recovery method of the present invention is preferably applied to a slag of a phosphorus-enriched phase having a higher phosphorus concentration from the viewpoint of phosphorus recovery efficiency.
本発明の製鋼スラグからのリン回収方法は、鉱酸を用いてリン成分をリン酸塩として回収する従来技術とは異なり、リン成分を遊離リン酸として回収することが可能である。 The method for recovering phosphorus from steelmaking slag according to the present invention is capable of recovering a phosphorus component as free phosphoric acid, unlike the conventional technique of recovering a phosphorus component as a phosphate using a mineral acid.
以下、本発明の実施の形態について、適宜図面を参酌しながら説明する。なお、本発明は以下の記載に限定されない。 Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. In addition, this invention is not limited to the following description.
本発明の製鋼スラグからのリン回収方法におけるプロセスフロー図の一例を、図１に示す。製鋼スラグは、まず、ジョークラッシャーやボールミル等によって最大粒子径が10〜100μm程度の大きさに粉砕される。 An example of a process flow diagram in the method for recovering phosphorus from steelmaking slag of the present invention is shown in FIG. The steelmaking slag is first pulverized by a jaw crusher or a ball mill to a maximum particle size of about 10 to 100 μm.
（溶出工程）
次に、リン濃縮相に、５mol/l（10N）以上の硫酸を加えて混合する。このとき、製鋼スラグに対する硫酸の混合比率は、製鋼スラグ1kgに対して硫酸10mol以上15mol以下とする。硫酸はリン濃縮相表面を濡らす程度とし、リン濃縮相が硫酸に浸漬するほどには混合しない。
(Elution process)
Next, 5 mol / l (10N) or more of sulfuric acid is added to the phosphorus-concentrated phase and mixed. At this time, the mixing ratio of sulfuric acid to steelmaking slag is 10 mol or more and 15 mol or less of sulfuric acid per 1 kg of steelmaking slag. Sulfuric acid wets the surface of the phosphorus-enriched phase and does not mix so much that the phosphorus-enriched phase is immersed in sulfuric acid.
リン濃縮相と強酸である硫酸とを反応させることにより、リン濃縮相に含有されるリン酸塩から弱酸であるリン酸（遊離リン酸）が溶出する。溶出したリン酸は、スラグ表面に付着した状態であり、そのままでは固液分離することができない。 By reacting the phosphorous concentrated phase with sulfuric acid that is a strong acid, phosphoric acid that is a weak acid (free phosphoric acid) is eluted from the phosphate contained in the phosphorous concentrated phase. The eluted phosphoric acid is attached to the surface of the slag and cannot be solid-liquid separated as it is.
（抽出工程）
そこで、リン濃縮相と硫酸との混合物に有機溶媒を加え、リン濃縮相表面に付着している遊離リン酸を有機溶媒に溶解させることにより、遊離リン酸を抽出する。有機溶媒として好ましい具体例は、メタノール、エタノール、1-ブタノール等の１級アルコールである。なお、後述する遊離リン酸回収工程で蒸発分離（減圧蒸発を含む）を行う際のエネルギーを低くする観点から、蒸発させる際の熱量の小さい有機溶媒であることが好ましい。このため、１級アルコールの中でも、メタノール又はエタノールが最も実用的である。
(Extraction process)
Therefore, the free phosphoric acid is extracted by adding an organic solvent to the mixture of the phosphorus concentrated phase and sulfuric acid and dissolving the free phosphoric acid adhering to the surface of the phosphorus concentrated phase in the organic solvent. Preferable specific examples of the organic solvent are primary alcohols such as methanol, ethanol and 1-butanol. In addition, it is preferable that it is an organic solvent with a small calorie | heat amount at the time of evaporating from a viewpoint of making low the energy at the time of performing evaporative separation (a vacuum evaporation is included) at the free phosphoric acid recovery process mentioned later. For this reason, methanol or ethanol is the most practical among primary alcohols.
本発明では、水ではなく有機溶媒を用いて遊離リン酸を溶解させるため、遊離リン酸がリン酸塩とならない。また、硫酸と混合することによって発生する水和熱も小さく、安全性が高い。遊離リン酸を充分に有機溶媒へ溶解させるためには、撹拌操作を行うことが好ましい。 In the present invention, since free phosphoric acid is dissolved using an organic solvent instead of water, the free phosphoric acid does not become a phosphate. Moreover, the heat of hydration generated by mixing with sulfuric acid is small, and safety is high. In order to sufficiently dissolve free phosphoric acid in an organic solvent, it is preferable to perform a stirring operation.
なお、添加する有機溶媒の量は特に限定されない。また、後段の濾過工程でも、洗浄もかねて同じ有機溶媒を添加することが好ましい。 Note that the amount of the organic solvent to be added is not particularly limited. In the subsequent filtration step, it is preferable to add the same organic solvent while washing.
有機溶媒に遊離リン酸を溶解させた後、ろ過操作や沈殿操作によって固液分離し、固形分は脱リンスラグとして回収される。遊離リン酸を溶解させた有機溶媒は、遊離リン酸回収工程に付される。このとき、リン濃縮相に含まれるカルシウム分と反応した残存硫酸は硫酸カルシウムとなっており、固液分離によって遊離リン酸を溶解させた有機溶媒と分離される。 After free phosphoric acid is dissolved in an organic solvent, solid-liquid separation is performed by filtration or precipitation, and the solid content is recovered as dephosphorization slag. The organic solvent in which free phosphoric acid is dissolved is subjected to a free phosphoric acid recovery step. At this time, the residual sulfuric acid that has reacted with the calcium content contained in the phosphorus-concentrated phase is calcium sulfate, which is separated from the organic solvent in which free phosphoric acid is dissolved by solid-liquid separation.
（遊離リン酸回収工程）
次に、遊離リン酸を溶解させた有機溶媒から、有機溶媒だけを蒸発させる。有機溶媒の蒸発は、蒸留装置を用いて蒸留することによって行いうる。蒸留装置の熱源としては、製鋼工程で発生する排熱を利用することが好ましい。有機溶媒の蒸留は、減圧蒸留としてもよい。蒸発させた有機溶媒は、凝集させることによって回収され、再利用される。有機溶媒が蒸発することにより、遊離リン酸だけを回収することができる。なお、回収された遊離リン酸は、必要に応じて公知の手段によって精製することもできる。
(Free phosphoric acid recovery process)
Next, only the organic solvent is evaporated from the organic solvent in which the free phosphoric acid is dissolved. The evaporation of the organic solvent can be performed by distillation using a distillation apparatus. As a heat source for the distillation apparatus, it is preferable to use exhaust heat generated in the steel making process. The organic solvent may be distilled under reduced pressure. The evaporated organic solvent is recovered by agglomeration and reused. As the organic solvent evaporates, only free phosphoric acid can be recovered. The recovered free phosphoric acid can be purified by known means if necessary.
本発明では、有機溶媒を使用して遊離リン酸の抽出を行うため、水を用いて遊離リン酸の抽出を行う場合と比較すると、溶媒蒸発に要するエネルギーが少ない。また、有機溶媒中では、水中と異なり遊離リン酸は電離しないため、リン酸塩が形成されにくく、純度の高い遊離リン酸を得ることが可能である。 In the present invention, since extraction of free phosphoric acid is performed using an organic solvent, less energy is required for solvent evaporation than when free phosphoric acid is extracted using water. In addition, unlike in water, free phosphoric acid is not ionized in an organic solvent, so that a phosphate is difficult to be formed, and high-purity free phosphoric acid can be obtained.
＜リン酸抽出実験＞
製鋼スラグ10g (粒子径 90μｍ以下）と、5mol/l〜15mol/lの硫酸とを混合した。混合する硫酸の量は、製鋼スラグ1kg当たりに換算して7.5mol〜15molとした。約5分間撹拌し、製鋼スラグと硫酸とを反応させた。その後、各種溶媒を約50mL加え、反応生成物を分散させ、同じ溶媒を用いてろ過及び洗浄した。
<Phosphate extraction experiment>
10 g of steelmaking slag (particle diameter of 90 μm or less) and 5 mol / l to 15 mol / l sulfuric acid were mixed. The amount of sulfuric acid to be mixed was 7.5 mol to 15 mol in terms of 1 kg of steelmaking slag. The mixture was stirred for about 5 minutes to react steelmaking slag with sulfuric acid. Thereafter, about 50 mL of various solvents were added to disperse the reaction product, followed by filtration and washing using the same solvent.
溶媒によって抽出した遊離リン酸量は、ＩＣＰ発光分析法で溶媒中のリン量を定量し、リン定量値に基づいて算出した。このとき、リン酸塩を形成するカルシウム分が存在しないことを確認した上で、リン定量値から遊離リン酸量を算出した。表１は、その結果を示す。 The amount of free phosphoric acid extracted with the solvent was calculated based on the quantitative value of phosphorus by quantifying the amount of phosphorus in the solvent by ICP emission spectrometry. At this time, after confirming that there was no calcium component forming phosphate, the amount of free phosphoric acid was calculated from the phosphorus quantitative value. Table 1 shows the results.
硫酸濃度10mol、製鋼スラグ1kg当たりの硫酸添加量を15molとした場合、溶媒がメタノール又はエタノールであれば、リン酸抽出率は90％以上となった。また、溶媒がイソブタノール又は1-ブタノールであってもリン酸抽出率は50％以上となった。しかし、溶媒がジエチルエーテルの場合には、リン酸抽出率がわずか3％に過ぎなかった。 When the sulfuric acid concentration was 10 mol and the amount of sulfuric acid added per 1 kg of steelmaking slag was 15 mol, the phosphoric acid extraction rate was 90% or more when the solvent was methanol or ethanol. Further, even when the solvent was isobutanol or 1-butanol, the phosphoric acid extraction rate was 50% or more. However, when the solvent was diethyl ether, the phosphoric acid extraction rate was only 3%.
また、エタノールを溶媒として用いる場合であっても、製鋼スラグ1kg当たりの硫酸添加量を7.5molとした場合、硫酸濃度が15mol/lであってもリン酸抽出率は26％に過ぎず、硫酸濃度が5mol/lであれば、リン酸抽出率は0に近かった。このように、製鋼スラグと反応させる硫酸濃度、硫酸量及び溶媒種類によって、リン酸抽出率は大きく変動することが確認された。 Even when ethanol is used as a solvent, when the amount of sulfuric acid added per 1 kg of steelmaking slag is 7.5 mol, even if the sulfuric acid concentration is 15 mol / l, the phosphoric acid extraction rate is only 26%, When the concentration was 5 mol / l, the phosphate extraction rate was close to 0. Thus, it was confirmed that the phosphoric acid extraction rate fluctuates greatly depending on the sulfuric acid concentration, the amount of sulfuric acid and the type of solvent to be reacted with steelmaking slag.
本発明の製鋼スラグからのリン回収方法は、製鉄分野、化学工業分野において、付加価値の高い遊離リン酸を回収する方法として有用である。 The method for recovering phosphorus from steelmaking slag according to the present invention is useful as a method for recovering free phosphoric acid having a high added value in the steelmaking field and the chemical industry field.
Claims (2)
溶出工程後の製鋼スラグ及び硫酸の混合物から、メタノール又はエタノールを用いて遊離リン酸を抽出する抽出工程と、
メタノール又はエタノールを蒸発させ、遊離リン酸を回収する遊離リン酸回収工程と、
を有し、
硫酸の濃度が5mol/l以上であり、
前記溶出工程において、製鋼スラグ1kgに対して硫酸10mol以上15mol以下を反応させる、製鋼スラグからのリン酸回収方法。 An elution step of reacting steelmaking slag with sulfuric acid to elute the phosphorus component contained in the steelmaking slag as free phosphoric acid;
From the steelmaking slag and sulfuric acid mixture after the elution step, an extraction step for extracting free phosphoric acid using methanol or ethanol ,
Free phosphoric acid recovery step of evaporating methanol or ethanol and recovering free phosphoric acid;
I have a,
The concentration of sulfuric acid is 5 mol / l or more,
A method for recovering phosphoric acid from steelmaking slag , wherein in the elution step, 10 kg or more and 15 mol or less of sulfuric acid are reacted with 1 kg of steelmaking slag.
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