JP5496122B2 - Method for producing high purity silica - Google Patents
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- JP5496122B2 JP5496122B2 JP2011018223A JP2011018223A JP5496122B2 JP 5496122 B2 JP5496122 B2 JP 5496122B2 JP 2011018223 A JP2011018223 A JP 2011018223A JP 2011018223 A JP2011018223 A JP 2011018223A JP 5496122 B2 JP5496122 B2 JP 5496122B2
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 title claims description 399
- 239000000377 silicon dioxide Substances 0.000 title claims description 188
- 238000004519 manufacturing process Methods 0.000 title claims description 37
- 239000007788 liquid Substances 0.000 claims description 107
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 87
- 239000007787 solid Substances 0.000 claims description 73
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 70
- 239000011707 mineral Substances 0.000 claims description 70
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 68
- 239000002253 acid Substances 0.000 claims description 64
- 239000012535 impurity Substances 0.000 claims description 60
- 239000007864 aqueous solution Substances 0.000 claims description 54
- 229910052910 alkali metal silicate Inorganic materials 0.000 claims description 45
- 238000000034 method Methods 0.000 claims description 44
- 238000000926 separation method Methods 0.000 claims description 41
- 239000002002 slurry Substances 0.000 claims description 40
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 36
- 239000000243 solution Substances 0.000 claims description 28
- 238000011084 recovery Methods 0.000 claims description 25
- 238000002156 mixing Methods 0.000 claims description 24
- 238000005406 washing Methods 0.000 claims description 20
- 239000002994 raw material Substances 0.000 claims description 14
- 230000002378 acidificating effect Effects 0.000 claims description 12
- 239000003513 alkali Substances 0.000 claims description 9
- 239000005416 organic matter Substances 0.000 claims description 8
- 238000010304 firing Methods 0.000 claims description 7
- RPAJSBKBKSSMLJ-DFWYDOINSA-N (2s)-2-aminopentanedioic acid;hydrochloride Chemical class Cl.OC(=O)[C@@H](N)CCC(O)=O RPAJSBKBKSSMLJ-DFWYDOINSA-N 0.000 claims description 6
- 238000001556 precipitation Methods 0.000 claims description 6
- 238000004090 dissolution Methods 0.000 claims description 4
- -1 In the step (B) Substances 0.000 claims description 3
- 239000004927 clay Substances 0.000 claims description 3
- 238000004140 cleaning Methods 0.000 claims description 3
- 238000000151 deposition Methods 0.000 claims description 2
- 238000001514 detection method Methods 0.000 description 68
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 66
- 239000010936 titanium Substances 0.000 description 55
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 34
- 239000011734 sodium Substances 0.000 description 30
- 235000019353 potassium silicate Nutrition 0.000 description 26
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 26
- 229910052719 titanium Inorganic materials 0.000 description 25
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 23
- 239000011575 calcium Substances 0.000 description 20
- 238000001035 drying Methods 0.000 description 19
- 239000011022 opal Substances 0.000 description 16
- 230000001376 precipitating effect Effects 0.000 description 15
- 229910052782 aluminium Inorganic materials 0.000 description 14
- 229910052742 iron Inorganic materials 0.000 description 12
- 235000012239 silicon dioxide Nutrition 0.000 description 12
- 229910052708 sodium Inorganic materials 0.000 description 11
- 239000000203 mixture Substances 0.000 description 10
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- 229910052710 silicon Inorganic materials 0.000 description 9
- 239000010703 silicon Substances 0.000 description 9
- 239000012153 distilled water Substances 0.000 description 8
- 238000005342 ion exchange Methods 0.000 description 8
- 235000010724 Wisteria floribunda Nutrition 0.000 description 7
- 239000010453 quartz Substances 0.000 description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 6
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 6
- 229910052796 boron Inorganic materials 0.000 description 6
- 229910052698 phosphorus Inorganic materials 0.000 description 6
- 239000000843 powder Substances 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 230000007423 decrease Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 3
- 239000005909 Kieselgur Substances 0.000 description 3
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 239000013522 chelant Substances 0.000 description 3
- QOSATHPSBFQAML-UHFFFAOYSA-N hydrogen peroxide;hydrate Chemical compound O.OO QOSATHPSBFQAML-UHFFFAOYSA-N 0.000 description 3
- 239000003456 ion exchange resin Substances 0.000 description 3
- 229920003303 ion-exchange polymer Polymers 0.000 description 3
- 238000010979 pH adjustment Methods 0.000 description 3
- 239000011574 phosphorus Substances 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- 229910052717 sulfur Inorganic materials 0.000 description 3
- 241000206761 Bacillariophyta Species 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 235000006408 oxalic acid Nutrition 0.000 description 2
- 238000000634 powder X-ray diffraction Methods 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- WSSDGZWSPMAECX-UHFFFAOYSA-N C1C2NCCC12 Chemical compound C1C2NCCC12 WSSDGZWSPMAECX-UHFFFAOYSA-N 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- GPATXKGIPSPFHV-UHFFFAOYSA-N Cl[SiH](Cl)Cl.Cl[Si](Cl)(Cl)Cl Chemical compound Cl[SiH](Cl)Cl.Cl[Si](Cl)(Cl)Cl GPATXKGIPSPFHV-UHFFFAOYSA-N 0.000 description 1
- 229910017488 Cu K Inorganic materials 0.000 description 1
- 229910017541 Cu-K Inorganic materials 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- MBBZMMPHUWSWHV-BDVNFPICSA-N N-methylglucamine Chemical group CNC[C@H](O)[C@@H](O)[C@H](O)[C@H](O)CO MBBZMMPHUWSWHV-BDVNFPICSA-N 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
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 229910002026 crystalline silica Inorganic materials 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 210000000805 cytoplasm Anatomy 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 229910052602 gypsum Inorganic materials 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000005502 peroxidation Methods 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
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Description
本発明は、高純度シリカの製造方法に関する。 The present invention relates to a method for producing high-purity silica.
高純度シリコンは、半導体デバイス、触媒担体等に用いられている。
高純度シリコンの製造方法として、例えば、金属シリコンから製造された高純度のシリコン塩化物（トリクロロシラン）を原料として用いる方法が提案されている（特許文献１）。
特許文献１に記載の方法によると、非常に高純度のシリコンを得ることができる。しかし、この方法は、工程が煩雑でかつ高コストであるという問題がある。このような事情下において、高純度のシリコンを、低コストかつ大量に製造することのできる技術が望まれている。
これを解決すべく、二酸化ケイ素を含有しかつ多孔質で微細構造を有する原料を精製して高純度シリカを製造し、次いで、この高純度シリカを原料としてシリコンを生成し、得られたシリコンにレーザを照射することなどによって、高純度シリコンを製造する方法が提案されている（特許文献２）。
High purity silicon is used for semiconductor devices, catalyst carriers and the like.
As a method for producing high-purity silicon, for example, a method using high-purity silicon chloride (trichlorosilane) produced from metal silicon as a raw material has been proposed (Patent Document 1).
According to the method described in Patent Document 1, very high-purity silicon can be obtained. However, this method has a problem that the process is complicated and expensive. Under such circumstances, a technique capable of manufacturing high-purity silicon at a low cost and in large quantities is desired.
In order to solve this, a raw material containing silicon dioxide and having a porous and fine structure is purified to produce high-purity silica, and then silicon is produced using this high-purity silica as a raw material. A method for producing high-purity silicon by irradiating a laser has been proposed (Patent Document 2).
特許文献２に記載の方法によると、従来技術に比して、低コストでかつ簡易に、高純度のシリコンを得ることができる。シリコンの原料となる高純度シリカを、より低コストでかつ簡易に得ることができれば、好都合である。
そこで、本発明は、高純度シリカを、簡易にかつ低コストで製造することのできる方法を提供することを目的とする。
According to the method described in Patent Document 2, high-purity silicon can be obtained at a lower cost and more easily than in the prior art. It would be advantageous if high-purity silica as a raw material for silicon could be obtained at a lower cost and more easily.
Then, an object of this invention is to provide the method which can manufacture high purity silica simply and at low cost.
本発明者は、上記課題を解決するために鋭意検討した結果、ケイ酸アルカリ水溶液と鉱酸を混合して、非ゲル状の沈降性シリカとして析出するとともに、製造工程において原料と過酸化水素を混合することによって、前記の目的を達成することができることを見出し、本発明を完成した。 As a result of diligent studies to solve the above problems, the present inventor mixed an alkali silicate aqueous solution and a mineral acid to precipitate as non-gelled precipitated silica, and the raw material and hydrogen peroxide in the production process. The inventors have found that the above object can be achieved by mixing, and completed the present invention.
すなわち、本発明は、以下の［１］〜［１２］を提供するものである。
［１］（Ｂ）液分中のＳｉ濃度が１０．０質量％以上のケイ酸アルカリ水溶液と１０．０体積％以上の濃度の鉱酸を混合して、液分中のＳｉを非ゲル状の沈降性シリカとして析出させた後、固液分離を行い、ＳｉＯ２を含む固形分と、不純物を含む液分を得るシリカ回収工程、を含み、前記工程（Ｂ）において、ケイ酸アルカリ水溶液、及び鉱酸の少なくともいずれか一方と過酸化水素を混合することを特徴とする高純度シリカの製造方法。
［２］（Ｃ）工程（Ｂ）で得られたＳｉＯ２を含む固形分と鉱酸を混合して、ｐＨが３．０未満の酸性スラリーを調製し、上記固形分中に残存する不純物を溶解させた後、上記酸性スラリーを固液分離して、ＳｉＯ２を含む固形分と、不純物を含む液分を得る酸洗浄工程、を含む前記［１］に記載の高純度シリカの製造方法。
［３］（Ｂ）液分中のＳｉ濃度が１０．０質量％以上のケイ酸アルカリ水溶液と１０．０体積％以上の濃度の鉱酸を混合して、液分中のＳｉを非ゲル状の沈降性シリカとして析出させた後、固液分離を行い、ＳｉＯ２を含む固形分と、不純物を含む液分を得るシリカ回収工程と、（Ｃ）工程（Ｂ）で得られたＳｉＯ２を含む固形分と鉱酸を混合して、ｐＨが３．０未満の酸性スラリーを調製し、上記固形分中に残存する不純物を溶解させた後、上記酸性スラリーを固液分離して、ＳｉＯ２を含む固形分と、不純物を含む液分を得る酸洗浄工程、を含み、前記工程（Ｃ）において、鉱酸と過酸化水素を混合することを特徴とする高純度シリカの製造方法。
［４］工程（Ｂ）において、ケイ酸アルカリ水溶液と鉱酸の混合が、ケイ酸アルカリ水溶液を鉱酸に添加することによって行われる、前記［１］〜［３］のいずれかに記載の高純度シリカの製造方法。
［５］工程（Ｂ）において、ケイ酸アルカリ水溶液と鉱酸を、ｐＨ１．０以下に保ちながら混合する、前記［１］〜［４］のいずれかに記載の高純度シリカの製造方法。
［６］工程（Ｂ）において、ケイ酸アルカリ水溶液のＳｉ濃度が１０．０〜２０．０質量％である、前記［１］〜［５］のいずれかに記載の高純度シリカの製造方法。
［７］過酸化水素の添加量が、シリカ（ＳｉＯ２）１００質量％に対して、０．１〜１５．０質量％である前記［１］〜［６］のいずれかに記載の高純度シリカの製造方法。
［８］工程（Ｂ）の前に、（Ａ）シリカ含有鉱物とアルカリ水溶液を混合して、ｐＨが１１．５以上のアルカリ性スラリーを調製し、液分中のＳｉ濃度が１０．０質量％以上となるように、上記シリカ含有鉱物中のＳｉを液分中に溶解させた後、上記アルカリ性スラリーを固液分離して、Ｓｉを含むケイ酸アルカリ水溶液と、固形分を得るアルカリ溶解工程を含む、前記［１］〜［７］のいずれかに記載の高純度シリカの製造方法。
［９］工程（Ａ）と工程（Ｂ）の間に、（Ｂ１）工程（Ａ）で得られたケイ酸アルカリ水溶液と酸を混合して、ｐＨを１０．３を超え、１１．５未満に調整し、液分中の不純物を析出させた後、固液分離を行い、ケイ酸アルカリ水溶液と、固形分を得る不純物回収工程、を含む、前記［８］に記載の高純度シリカの製造方法。
［１０］工程（Ａ）の前に、（Ａ１）シリカ含有鉱物を水洗して、粘土分及び有機物を除去する原料水洗工程、を含む前記［８］または［９］に記載の高純度シリカの製造方法。
［１１］工程（Ａ）の前に、（Ａ２）シリカ含有鉱物を３００〜１０００℃で０．５〜２時間焼成して、有機物を除去する原料焼成工程、を含む前記［８］〜［１０］のいずれかに記載の高純度シリカの製造方法。
［１２］（Ｄ）前工程で得られたＳｉＯ２を含む固形分と水を混合して、上記固形分中に残存する不純物を溶解させた後、上記スラリーを固液分離して、ＳｉＯ２を含む固形分と、不純物を含む液分を得る水洗浄工程、を含む前記［１］〜［１１］のいずれかに記載の高純度シリカの製造方法。
That is, the present invention provides the following [1] to [12].
[1] (B) An alkali silicate aqueous solution having a Si concentration of 10.0% by mass or more and a mineral acid having a concentration of 10.0% by volume or more are mixed, and the Si in the liquid is non-gelled In the step (B), an aqueous solution of alkali silicate, and a silica recovery step for obtaining a solid content containing SiO 2 and a liquid content containing impurities are performed. And a method for producing high purity silica, wherein hydrogen peroxide is mixed with at least one of mineral acids.
[2] (C) The solid content containing SiO 2 obtained in step (B) and mineral acid are mixed to prepare an acidic slurry having a pH of less than 3.0, and impurities remaining in the solid content are removed. After dissolving, the acidic slurry is subjected to solid-liquid separation, and the method for producing high-purity silica according to the above [1], comprising an acid washing step for obtaining a solid content containing SiO 2 and a liquid content containing impurities.
[3] (B) An alkali silicate aqueous solution having a Si concentration of 10.0% by mass or more and a mineral acid having a concentration of 10.0% by volume or more are mixed, and the Si in the liquid is non-gelled. The silica is recovered as a precipitated silica, and then subjected to solid-liquid separation to obtain a solid content including SiO 2 and a liquid content including impurities, and (C) SiO 2 obtained in the step (B). The solid content and mineral acid included are mixed to prepare an acidic slurry having a pH of less than 3.0. After the impurities remaining in the solid content are dissolved, the acidic slurry is subjected to solid-liquid separation, and SiO 2 A method for producing high-purity silica, comprising: mixing a solid content containing an acid; and an acid washing step for obtaining a liquid containing an impurity, wherein the mineral acid and hydrogen peroxide are mixed in the step (C).
[4] In the step (B), the mixing of the alkali silicate aqueous solution and the mineral acid is performed by adding the alkali silicate aqueous solution to the mineral acid, according to any one of the above [1] to [3]. A method for producing pure silica.
[5] The method for producing high-purity silica according to any one of [1] to [4], wherein in the step (B), the alkali silicate aqueous solution and the mineral acid are mixed while being kept at pH 1.0 or lower.
[6] The method for producing high-purity silica according to any one of [1] to [5], wherein in the step (B), the Si concentration of the alkali silicate aqueous solution is 10.0 to 20.0 mass%.
[7] The addition amount of hydrogen peroxide, silica (SiO 2) with respect to 100 wt%, high purity according to any one of the is 0.1 to 15.0 wt% [1] - [6] A method for producing silica.
[8] Before step (B), (A) silica-containing mineral and alkaline aqueous solution are mixed to prepare an alkaline slurry having a pH of 11.5 or more, and the Si concentration in the liquid is 10.0% by mass. As described above, after dissolving Si in the silica-containing mineral in the liquid, the alkaline slurry is subjected to solid-liquid separation, and an alkali silicate aqueous solution containing Si and an alkali dissolution step for obtaining a solid content. The manufacturing method of the high purity silica in any one of said [1]-[7] containing.
[9] Between step (A) and step (B), (B1) alkaline silicate aqueous solution obtained in step (A) and an acid are mixed, and the pH exceeds 10.3 and less than 11.5 The high-purity silica according to [8], which includes an alkali silicate aqueous solution and an impurity recovery step for obtaining a solid content by performing solid-liquid separation after the impurities in the liquid are precipitated. Method.
[10] Before the step (A), (A1) The raw material water washing step of washing the silica-containing mineral with water to remove the clay and the organic matter, and the high-purity silica according to [8] or [9] Production method.
[11] Prior to step (A), (A2) a raw material firing step for removing the organic matter by firing the silica-containing mineral at 300 to 1000 ° C. for 0.5 to 2 hours. ] The manufacturing method of the high purity silica in any one of.
[12] (D) After mixing the solid content containing SiO 2 obtained in the previous step and water to dissolve impurities remaining in the solid content, the slurry is subjected to solid-liquid separation to obtain SiO 2. The manufacturing method of the high purity silica in any one of said [1]-[11] including the water washing process which obtains the solid content containing an impurity, and the liquid component containing an impurity.
本発明の高純度シリカの製造方法によると、操作が簡易であり、処理効率が高いことなどに起因して、従来技術に比して低い製造コストで高純度シリカを得ることができる。
さらに、本発明の製造方法により得られる高純度シリカは、シリカの含有率が高く、またアルミニウム（Ａｌ）、鉄（Ｆｅ）、チタン（Ｔｉ）、ホウ素（Ｂ）、リン（Ｐ）、有機物（Ｃ）などの不純物、特にチタン（Ｔｉ）の含有率が低いという特長がある。
According to the method for producing high-purity silica of the present invention, high-purity silica can be obtained at a production cost lower than that of the prior art due to simple operation and high processing efficiency.
Furthermore, the high-purity silica obtained by the production method of the present invention has a high silica content, and aluminum (Al), iron (Fe), titanium (Ti), boron (B), phosphorus (P), organic matter ( It has a feature that the content of impurities such as C), particularly titanium (Ti), is low.
以下、本発明の高純度シリカの製造方法を詳しく説明する。
なお、以下の工程（Ａ１）〜工程（Ｄ）中、工程（Ｂ）は、本発明において必須の工程であるが、工程（Ａ）は、シリカ含有鉱物を原料としてケイ酸アルカリ水溶液を調製する場合に追加される工程であり、工程（Ａ１）、（Ａ２）、（Ｂ１）、（Ｃ）及び（Ｄ）は、本発明において必須ではなく、任意で追加可能な工程である。
［工程（Ａ１）；原料水洗工程］
工程（Ａ１）は、シリカ含有鉱物（岩石状又は粉末状）を水洗して、粘土分及び有機物を除去する工程である。水洗後のシリカ含有鉱物は、通常、フィルタープレス等を用いて、さらに脱水させる。
シリカ含有鉱物としては、珪藻土、珪質頁岩等が挙げられる。シリカ含有鉱物は、アルカリに対する溶解性が高いことが望ましい。
ここで、珪藻土とは、珪藻が海底や湖底に沈積し、長い年月の間に体内の原形質その他の有機物が分解し、非晶質シリカを主体とした珪藻殻が集積して堆積したものである。
珪質頁岩とは、珪質の生物遺骸等に由来する頁岩である。すなわち、海域には、珪質の殻を有する珪藻などのプランクトンが生息するが、このプランクトンの死骸が海底中に堆積すると、死骸中の有機物の部分は徐々に分解され、珪質（ＳｉＯ２；シリカ）の殻のみが残る。この珪質の殻（珪質堆積物）が、時間の経過や温度・圧力の変化などに伴い、続成作用により変質して、硬岩化することにより珪質頁岩となる。なお、珪質堆積物中のシリカは、続成作用によって、非晶質シリカから、結晶化してクリストバライト、トリデイマイトへ、さらに石英へと変化する。
Hereinafter, the manufacturing method of the high purity silica of this invention is demonstrated in detail.
In the following steps (A1) to (D), step (B) is an essential step in the present invention. In step (A), an alkali silicate aqueous solution is prepared using a silica-containing mineral as a raw material. Steps (A1), (A2), (B1), (C), and (D) are not essential in the present invention, and can be arbitrarily added.
[Step (A1); Raw material washing step]
The step (A1) is a step of washing the silica-containing mineral (rock or powder) with water to remove clay and organic matter. The silica-containing mineral after washing is usually further dehydrated using a filter press or the like.
Examples of the silica-containing mineral include diatomaceous earth and siliceous shale. The silica-containing mineral is desirably highly soluble in alkali.
Here, diatomaceous earth is a deposit of diatom shells mainly composed of amorphous silica, where diatoms are deposited on the sea floor and lake bottom, and protoplasms and other organic substances in the body decompose over a long period of time. It is.
Siliceous shale is shale derived from siliceous biological remains. That is, planktons such as diatoms with siliceous shells inhabit the sea area, but when the dead bodies of plankton are deposited in the seabed, the organic matter part in the dead bodies is gradually decomposed and siliceous (SiO 2 ; Only the silica shell remains. This siliceous shell (siliceous deposit) becomes siliceous shale when it changes in quality due to diagenesis and hardens as time passes and temperature and pressure change. Silica in the siliceous deposit is crystallized from crystallization to cristobalite, tridayite, and further to quartz by diagenesis.
珪藻土は、主に非晶質シリカであるオパールＡからなる。珪質頁岩は、オパールＡより結晶化が進んだオパールＣＴまたはオパールＣを主に含む。オパールＣＴとは、クリストバライト構造とトリディマイト構造からなるシリカ鉱物である。オパールＣとは、クリストバライト構造からなるシリカ鉱物である。このうち、本発明では、オパールＣＴを主とする珪質頁岩が好ましく用いられる。
さらに、Ｃｕ−Ｋα線による粉末Ｘ線回折において、石英の２θ＝２６．６ｄｅｇのピーク頂部の回折強度に対するオパールＣＴの２θ＝２１．５〜２１．９ｄｅｇの回折強度は、石英を１とした場合の比率で０．２〜２．０の範囲が好ましく、０．４〜１．８の範囲がより好ましく、０．５〜１．５の範囲が特に好ましい。該値が０．２に満たない場合には、反応性に富むオパールＣＴの量が少ないため、シリカの収量が低下する。一方、該値が２．０を超える場合には、オパールＣＴの量が石英よりはるかに多くなり、このような珪質頁岩は資源的に少なく、経済性に劣る。
なお、石英に対するオパールＣＴの回折強度の比率は、以下の式で求める。
石英に対するオパールＣＴの回折強度の比率＝（２１．５〜２１．９ｄｅｇのピーク頂部の回折強度）／（２６．６ｄｅｇのピーク頂部の回折強度）
また、珪質頁岩のＣｕ−Ｋα線による粉末Ｘ線回折において、オパールＣＴの２θ＝２１．５〜２１．９ｄｅｇの間に存在するピークの半値幅は０．５°以上が好ましく、０．７５°以上がより好ましく、１．０°以上がさらに好ましい。該値が０．５°未満では、オパールＣＴの結晶の結合力が増大し、アルカリとの反応性が低下して、シリカの収量が減少する。ここで、半値幅とは、ピーク頂部の回折強度の１／２に位置する回折線の幅をいう。
本発明で用いる珪質頁岩は、シリカ含有率が７０質量％以上であることが好ましく、７５質量％以上であることがより好ましい。このような珪質頁岩を用いることにより、より高純度のシリカを低コストで製造することができる。
シリカ含有鉱物は、例えば、珪質頁岩等のシリカ含有鉱物を粉砕装置（例えば、ジョークラッシャー、トップグラインダーミル、クロスビーターミル、ボールミル等）で粉砕することによって得ることができる。
［工程（Ａ２）；原料焼成工程］
工程（Ａ２）は、シリカ含有鉱物を３００〜１０００℃で０．５〜２時間焼成し、有機物を除去する工程である。
なお、工程（Ａ１）と工程（Ａ２）の双方を実施する場合、その順序は特に限定されないが、有機物の除去効率の観点から工程（Ａ１）を先に行うことが好ましい。
Diatomaceous earth is mainly composed of opal A, which is amorphous silica. The siliceous shale mainly contains opal CT or opal C which has been crystallized more than opal A. Opal CT is a silica mineral having a cristobalite structure and a tridymite structure. Opal C is a silica mineral having a cristobalite structure. Of these, siliceous shale mainly composed of opal CT is preferably used in the present invention.
Further, in the powder X-ray diffraction by Cu-Kα ray, the diffraction intensity of 2θ = 21.5 to 21.9 deg of opal CT with respect to the diffraction intensity of 2θ = 26.6 deg peak of quartz is 1 when quartz is 1. The ratio of 0.2 to 2.0 is preferable, the range of 0.4 to 1.8 is more preferable, and the range of 0.5 to 1.5 is particularly preferable. When the value is less than 0.2, the amount of opal CT rich in reactivity is small, and the yield of silica is reduced. On the other hand, when the value exceeds 2.0, the amount of opal CT is much larger than that of quartz, and such siliceous shale is less resource and less economical.
In addition, the ratio of the diffraction intensity of opal CT with respect to quartz is calculated | required with the following formula | equation.
Ratio of diffraction intensity of opal CT to quartz = (diffraction intensity at peak top of 21.5 to 21.9 deg) / (diffraction intensity at peak top of 26.6 deg)
Moreover, in the powder X-ray diffraction of the siliceous shale by Cu—Kα ray, the half width of the peak existing between 2θ = 21.5 to 21.9 deg of the opal CT is preferably 0.5 ° or more, and 0.75 More preferably, the angle is more than 1.0 °, and more preferably more than 1.0 °. If the value is less than 0.5 °, the bonding strength of the opal CT crystals increases, the reactivity with alkali decreases, and the yield of silica decreases. Here, the half-value width means the width of a diffraction line located at half the diffraction intensity at the peak top.
The siliceous shale used in the present invention preferably has a silica content of 70% by mass or more, and more preferably 75% by mass or more. By using such siliceous shale, higher purity silica can be produced at low cost.
The silica-containing mineral can be obtained, for example, by pulverizing a silica-containing mineral such as siliceous shale with a pulverizer (eg, jaw crusher, top grinder mill, cross beater mill, ball mill, etc.).
[Step (A2); raw material firing step]
The step (A2) is a step of removing the organic matter by baking the silica-containing mineral at 300 to 1000 ° C. for 0.5 to 2 hours.
In addition, when implementing both a process (A1) and a process (A2), the order is not specifically limited, However, It is preferable to perform a process (A1) previously from a viewpoint of the removal efficiency of organic substance.
［工程（Ａ）；アルカリ溶解工程］
工程（Ａ）は、シリカ含有鉱物とアルカリ水溶液を混合して、ｐＨが１１．５以上のアルカリ性スラリーを調製し、液分中のＳｉ濃度が１０．０質量％以上となるように、上記シリカ含有鉱物中のＳｉを液分中に溶解させた後、上記アルカリ性スラリーを固液分離して、Ｓｉを含むケイ酸アルカリ水溶液と、固形分を得るアルカリ溶解工程である。
ここで、ケイ酸アルカリ水溶液とは、化学式中にケイ酸（ＳｉＯ２）を含む物質を含有するアルカリ性の水溶液をいう。
シリカ含有鉱物とアルカリ水溶液を混合してなるアルカリ性スラリーのｐＨは、１１．５以上、好ましくは１２．５以上、より好ましくは１３．０以上となるように調整される。該ｐＨが１１．５未満であると、シリカを十分に溶解させることができず、シリカが固形分中に残存してしまうため、得られるシリカの収量が減少する。
ｐＨを上記数値範囲内に調整するためのアルカリ水溶液としては、水酸化ナトリウム水溶液、水酸化カリウム水溶液等が用いられる。
スラリーの固液比（アルカリ水溶液１リットルに対するシリカ含有鉱物の質量）は、好ましくは１００〜５００ｇ／リットル、より好ましくは２００〜４００ｇ／リットルである。該固液比が１００ｇ／リットル未満では、スラリーの固液分離に要する時間が増大するなど、処理効率が低下する。該固液比が４００ｇ／リットルを超えると、シリカ等を十分に溶出させることができないことがある。
スラリーは、通常、所定時間（例えば、３０〜９０分間）攪拌される。
攪拌後のスラリーは、フィルタープレス等の固液分離手段を用いて、固形分と液分に分離される。液分は、Ｓｉ及び他の成分（Ａｌ、Ｆｅ等の不純物）を含むケイ酸アルカリ水溶液であり、次の工程（Ｂ１）または工程（Ｂ）で処理される。液分中に含まれるＳｉの濃度は、１０．０質量％以上、好ましくは１０．０〜２０．０質量％、より好ましくは１２．０〜１８．０質量％、特に好ましくは１３．０〜１６．０質量％である。Ｓｉ濃度が１０．０質量％未満であると、後述する工程（Ｂ）においてシリカがゲル状で析出する場合があり、固液分離に時間がかかるとともに、得られるシリカの量が低下する。
なお、本工程においてアルカリ性スラリーを得る際の液温は、エネルギーコストの観点から、５〜１００℃に保持されることが好ましく、１０〜８０℃に保持されることがより好ましく、１０〜４０℃に保持されることが特に好ましい。液温を上記範囲内とすることにより、処理効率を高めることができる。
[Step (A); alkali dissolution step]
In the step (A), the silica-containing mineral and the aqueous alkali solution are mixed to prepare an alkaline slurry having a pH of 11.5 or higher, and the silica concentration is set to 10.0% by mass or higher. This is an alkali dissolution step in which Si in the contained mineral is dissolved in the liquid, and then the alkaline slurry is subjected to solid-liquid separation to obtain an alkali silicate aqueous solution containing Si and a solid.
Here, the alkali silicate aqueous solution refers to an alkaline aqueous solution containing a substance containing silicic acid (SiO 2 ) in the chemical formula.
The pH of the alkaline slurry formed by mixing the silica-containing mineral and the alkaline aqueous solution is adjusted to be 11.5 or higher, preferably 12.5 or higher, more preferably 13.0 or higher. When the pH is less than 11.5, the silica cannot be sufficiently dissolved, and the silica remains in the solid content, so that the yield of the resulting silica is reduced.
Examples of the alkaline aqueous solution for adjusting the pH within the above numerical range include a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution.
The solid-liquid ratio of the slurry (the mass of the silica-containing mineral with respect to 1 liter of the aqueous alkali solution) is preferably 100 to 500 g / liter, more preferably 200 to 400 g / liter. When the solid-liquid ratio is less than 100 g / liter, the processing efficiency decreases, for example, the time required for solid-liquid separation of the slurry increases. If the solid-liquid ratio exceeds 400 g / liter, silica or the like may not be sufficiently eluted.
The slurry is usually stirred for a predetermined time (for example, 30 to 90 minutes).
The slurry after stirring is separated into a solid content and a liquid content using a solid-liquid separation means such as a filter press. The liquid component is an alkali silicate aqueous solution containing Si and other components (impurities such as Al and Fe), and is treated in the next step (B1) or step (B). The concentration of Si contained in the liquid component is 10.0% by mass or more, preferably 10.0 to 20.0% by mass, more preferably 12.0 to 18.0% by mass, and particularly preferably 13.0 to 16.0% by mass. When the Si concentration is less than 10.0% by mass, silica may precipitate in a gel form in the step (B) described later, and it takes time for solid-liquid separation, and the amount of silica obtained is reduced.
In addition, it is preferable that the liquid temperature at the time of obtaining an alkaline slurry in this process is 5-100 degreeC from a viewpoint of energy cost, It is more preferable to hold | maintain at 10-80 degreeC, 10-40 degreeC It is particularly preferable that the By setting the liquid temperature within the above range, the processing efficiency can be increased.
［工程（Ｂ１）；不純物回収工程］
本工程は、工程（Ａ）で得られたケイ酸アルカリ水溶液と酸を混合して、ｐＨを１０．３を超え、１１．５未満に調整し、液分中のＳｉ以外の不純物（例えば、Ａｌ及びＦｅ）を析出させた後、固液分離を行い、Ｓｉを含むケイ酸アルカリ水溶液と、固形分を得る工程である。
なお、本工程で回収されずに液分中に残存する不純物は、工程（Ｂ）以降の工程で回収される。
本工程において、酸との混合後の液分のｐＨは、１０．３を超え、１１．５未満、好ましくは１０．４以上、１１．０以下、特に好ましくは１０．５以上、１０．８以下である。該ｐＨが１０．３以下であると、不純物（例えば、Ａｌ及びＦｅ）と共にＳｉも析出してしまう。一方、該ｐＨが１１．５以上では、十分に析出せずに液分中に残存する不純物（例えば、Ａｌ及びＦｅ）の量が多くなる。
ｐＨを上記数値範囲内に調整するための酸としては、硫酸、塩酸、シュウ酸等が用いられる。
ｐＨ調整後、フィルタープレス等の固液分離手段を用いて、固形分と液分に分離する。
このうち、固形分（ケーキ）は、不純物（例えば、Ａｌ及びＦｅ）を含むものである。
液分は、Ｓｉを含むものであり、次の工程（Ｂ）で処理される。
なお、本工程においてｐＨ調整を行う際の液温は、エネルギーコストの観点から、５
〜１００℃に保持されることが好ましく、１０〜８０℃に保持されることがより好ましく、１０〜４０℃に保持されることが特に好ましい。液温を上記範囲内とすることにより、処理効率を高めることができる。
[Step (B1); impurity recovery step]
In this step, the alkali silicate aqueous solution obtained in step (A) and an acid are mixed to adjust the pH to more than 10.3 and less than 11.5, and impurities other than Si in the liquid (for example, After Al and Fe) are precipitated, solid-liquid separation is performed to obtain an alkali silicate aqueous solution containing Si and a solid content.
Impurities remaining in the liquid without being recovered in this step are recovered in the steps after the step (B).
In this step, the pH of the liquid after mixing with the acid is more than 10.3 and less than 11.5, preferably 10.4 or more, 11.0 or less, particularly preferably 10.5 or more, 10.8. It is as follows. When the pH is 10.3 or less, Si is also precipitated together with impurities (for example, Al and Fe). On the other hand, when the pH is 11.5 or more, the amount of impurities (for example, Al and Fe) remaining in the liquid without being sufficiently precipitated increases.
As the acid for adjusting the pH within the above numerical range, sulfuric acid, hydrochloric acid, oxalic acid and the like are used.
After the pH adjustment, the solid and liquid components are separated using a solid-liquid separation means such as a filter press.
Among these, solid content (cake) contains impurities (for example, Al and Fe).
The liquid component contains Si and is processed in the next step (B).
In addition, the liquid temperature at the time of pH adjustment in this step is 5 from the viewpoint of energy cost.
It is preferable to hold | maintain at -100 degreeC, It is more preferable to hold | maintain at 10-80 degreeC, It is especially preferable to hold | maintain at 10-40 degreeC. By setting the liquid temperature within the above range, the processing efficiency can be increased.
［工程（Ｂ）；シリカ回収工程］
本工程は、液分中のＳｉ濃度が１０．０質量％以上のケイ酸アルカリ水溶液と１０．０体積％以上の濃度の鉱酸を混合して、液分中のＳｉを非ゲル状の沈降性シリカとして析出させた後、固液分離を行い、ＳｉＯ２を含む固形分と、不純物を含む液分を得る工程である。
なお、沈降性シリカは、ケイ酸アルカリ水溶液と鉱酸との混合と同時に生成する。
本工程において用いられるケイ酸アルカリ水溶液は、特に限定されないが、具体的には前工程（工程（Ａ）または工程（Ｂ１））で得られたケイ酸アルカリ水溶液、及び水ガラス等が挙げられる。
本発明で用いられる水ガラスは、市販のものを使用することができ、ＪＩＳ規格により規定される１号、２号、３号の他に各水ガラスメーカーで製造販売されているＪＩＳ規格外の製品も使用することができる。
ケイ酸アルカリ水溶液中に含まれるＳｉの濃度は、１０．０質量％以上、好ましくは
１０．０〜２０．０質量％、より好ましくは１２．０〜１８．０質量％、特に好ましくは１３．０〜１６．０質量％である。Ｓｉ濃度が１０．０質量％未満であると、シリカがゲル状で析出する場合があり、固液分離に時間がかかるとともに、得られるシリカの量が低下する。
Ｓｉ濃度が２０質量％を超えると、ケイ酸アルカリ水溶液のハンドリング（輸送等）が悪化するとともに、不純物の除去が不十分となる場合がある。
本工程において用いられる鉱酸は、例えば硫酸、塩酸、硝酸等が挙げられ、硫酸を用いることが薬剤コスト低減の理由で好ましい。
鉱酸の濃度は、１０．０体積％以上、より好ましくは１０．０〜２０．０体積％、特に好ましくは１０．０〜１５．０体積％である。鉱酸の濃度が、１０．０体積％未満の場合には、沈降性シリカが生成しない、あるいは沈降性シリカとゲル状シリカの両方が生成するおそれがある。このゲル状シリカが生成すると、最終シリカ生成物中の不純物濃度が高くなる。２０．０体積％を超えるとコストの面から好ましくない。
ケイ酸アルカリ水溶液と鉱酸の混合方法は、特に限定されるものではないが、沈降性シリカのみを生成させる観点から、ケイ酸アルカリ水溶液を鉱酸に添加する方法が好ましい。具体的には、ケイ酸アルカリ水溶液を鉱酸に滴下する方法や、ケイ酸アルカリ水溶液を、１．０ｍｍφ以上、好ましくは４．０ｍｍφ以上のチューブ等から、鉱酸中に直接押し出す方法等が挙げられる。
また、混合する際のｐＨは好ましくは１．０以下、より好ましくは０．９以下に保つことが望ましい。ｐＨが１．０を超えるとシリカがゲル状で析出する場合があり、固液分離に時間がかかるとともに、得られるシリカの量が低下する。
また、ケイ酸アルカリ水溶液の鉱酸中への流出速度は限定されないが、混合する際にｐＨが１．０を超え、かつ流出速度が大きい場合には、沈降性シリカが生成しない、あるいは沈降性シリカとゲル状シリカの両方が生成するおそれがある。
本工程において、ケイ酸アルカリ水溶液と鉱酸を混合する際の沈降性シリカの析出温度は、特に限定されるものではないが、好ましくは１０〜８０℃、より好ましくは１５〜４０℃、特に好ましくは２０〜３０℃であり、通常、常温（例えば１０〜４０℃）である。８０℃を超えると、エネルギーコストが上昇するとともに、設備の腐食が生じ易くなる。
上記ケイ酸アルカリ水溶液中のＳｉを沈降性シリカとして析出させた後、フィルタープレス等の固液分離手段を用いて、ＳｉＯ２を含む固形分と、不純物を含む液分に分離する。得られた沈降性シリカはゲル状ではなく、粒子状であるため、固液分離に要する時間を短くすることができる。
[Step (B); silica recovery step]
In this step, an alkali silicate aqueous solution having a Si concentration of 10.0% by mass or more and a mineral acid having a concentration of 10.0% by volume or more are mixed to precipitate Si in the liquid in a non-gelled state. This is a step of performing solid-liquid separation after depositing as crystalline silica to obtain a solid content containing SiO 2 and a liquid content containing impurities.
Precipitated silica is produced simultaneously with the mixing of the alkali silicate aqueous solution and the mineral acid.
Although the alkali silicate aqueous solution used in this step is not particularly limited, specifically, the alkali silicate aqueous solution obtained in the previous step (step (A) or step (B1)), water glass and the like can be mentioned.
As the water glass used in the present invention, commercially available ones can be used. In addition to Nos. 1, 2, and 3 defined by the JIS standard, the water glass is manufactured and sold by each water glass manufacturer. Products can also be used.
The concentration of Si contained in the alkali silicate aqueous solution is 10.0% by mass or more, preferably 10.0 to 20.0% by mass, more preferably 12.0 to 18.0% by mass, and particularly preferably 13. It is 0-16.0 mass%. When the Si concentration is less than 10.0% by mass, silica may precipitate in a gel state, and it takes time for solid-liquid separation, and the amount of silica to be obtained decreases.
When the Si concentration exceeds 20% by mass, handling (transportation, etc.) of the alkali silicate aqueous solution deteriorates, and removal of impurities may be insufficient.
Examples of the mineral acid used in this step include sulfuric acid, hydrochloric acid, nitric acid and the like, and it is preferable to use sulfuric acid for the reason of reducing the chemical cost.
The concentration of the mineral acid is 10.0% by volume or more, more preferably 10.0 to 20.0% by volume, and particularly preferably 10.0 to 15.0% by volume. When the concentration of the mineral acid is less than 10.0% by volume, the precipitated silica may not be generated, or both precipitated silica and gel silica may be generated. When this gel silica is generated, the impurity concentration in the final silica product is increased. When it exceeds 20.0 volume%, it is not preferable from the surface of cost.
The method for mixing the alkali silicate aqueous solution and the mineral acid is not particularly limited, but a method of adding the alkali silicate aqueous solution to the mineral acid is preferable from the viewpoint of producing only precipitated silica. Specifically, a method of dropping an alkali silicate aqueous solution onto a mineral acid, a method of directly extruding an alkali silicate aqueous solution into a mineral acid from a tube of 1.0 mmφ or more, preferably 4.0 mmφ or more, etc. It is done.
Further, the pH during mixing is preferably 1.0 or less, and more preferably 0.9 or less. If the pH exceeds 1.0, silica may precipitate in a gel form, and it takes time for solid-liquid separation, and the amount of silica to be obtained decreases.
Moreover, the outflow rate of the aqueous alkali silicate solution into the mineral acid is not limited. However, when the pH exceeds 1.0 and the outflow rate is high when mixing, no precipitated silica is formed or the settling property is increased. Both silica and gel silica may be generated.
In this step, the precipitation temperature of the precipitated silica when mixing the alkali silicate aqueous solution and the mineral acid is not particularly limited, but is preferably 10 to 80 ° C, more preferably 15 to 40 ° C, and particularly preferably. Is 20-30 degreeC and is normal temperature (for example, 10-40 degreeC) normally. When the temperature exceeds 80 ° C., the energy cost increases and the equipment is easily corroded.
After precipitating Si in the alkali silicate aqueous solution as precipitated silica, it is separated into a solid content containing SiO 2 and a liquid content containing impurities using a solid-liquid separation means such as a filter press. Since the obtained precipitated silica is not in a gel form but in a particulate form, the time required for solid-liquid separation can be shortened.
本発明では、工程（Ｂ）において、ケイ酸アルカリ水溶液、及び鉱酸の少なくともいずれか一方と過酸化水素を混合することで、不純物（特にＴｉ）が低減された高純度シリカを得ることができる。
混合方法は特に限定されるものではなく、（１）ケイ酸アルカリ水溶液と過酸化水素を混合し、次いで得られた混合物と鉱酸を混合する方法、（２）鉱酸と過酸化水素を混合し、次いで得られた混合物とケイ酸アルカリ水溶液を混合する方法、（３）ケイ酸アルカリ水溶液と鉱酸を混合し、次いで得られた混合物と過酸化水素を混合する方法、（４）ケイ酸アルカリ水溶液と、鉱酸と、過酸化水素を同時に混合する方法が挙げられる。中でも、工程の上流側で不純物（特にＴｉ）の低減を図るという観点から（１）が好ましい。
過酸化水素の添加量は、シリカ（ＳｉＯ２）の質量（１００質量％）に対して、好ましくは０．１〜１５．０質量％、より好ましくは０．１〜１０．０質量％、特に好ましくは０．１〜５．０質量％である。過酸化水素の添加量が０．１質量％未満では、不純物（例えばＴｉ）の低減効果が十分ではなく、１５．０質量％を超えると、不純物（例えばＴｉ）の低減効果が飽和状態となる。
In the present invention, high purity silica with reduced impurities (particularly Ti) can be obtained by mixing hydrogen peroxide with at least one of an alkali silicate aqueous solution and a mineral acid in step (B). .
The mixing method is not particularly limited. (1) A method in which an alkali silicate aqueous solution and hydrogen peroxide are mixed, and then the resulting mixture and mineral acid are mixed. (2) A mineral acid and hydrogen peroxide are mixed. Next, a method of mixing the obtained mixture and an alkali silicate aqueous solution, (3) a method of mixing an alkali silicate aqueous solution and mineral acid, and then mixing the resulting mixture and hydrogen peroxide, (4) silicic acid A method of simultaneously mixing an alkaline aqueous solution, a mineral acid, and hydrogen peroxide is mentioned. Among these, (1) is preferable from the viewpoint of reducing impurities (particularly Ti) on the upstream side of the process.
The amount of hydrogen peroxide added is preferably 0.1 to 15.0% by mass, more preferably 0.1 to 10.0% by mass, and particularly preferably 0.1% to 10.0% by mass with respect to the mass (100% by mass) of silica (SiO 2 ). Preferably it is 0.1-5.0 mass%. If the amount of hydrogen peroxide added is less than 0.1% by mass, the effect of reducing impurities (eg, Ti) is not sufficient, and if it exceeds 15.0% by mass, the effect of reducing impurities (eg, Ti) becomes saturated. .
工程（Ｂ）において用いられる鉱酸が硫酸である場合、工程（Ｂ）で得られた不純物を含む液分を中和処理することで、液分中の不純物を石膏として析出し、セメントの原料として再利用してもよい。 When the mineral acid used in the step (B) is sulfuric acid, by neutralizing the liquid containing the impurities obtained in the step (B), the impurities in the liquid are precipitated as gypsum, and the raw material for cement May be reused as
［工程（Ｃ）；酸洗浄工程］
工程（Ｂ）で得られたＳｉＯ２を含む固形分は、Ａｌ、Ｆｅ、Ｔｉ、Ｂ、Ｐ等の不純物が低減された高純度シリカである。
工程（Ｂ）で得られたＳｉＯ２を含む固形分に対して、適宜、工程（Ｃ）（酸洗浄工程）を行うことができる。酸洗浄工程を行うことにより、より高純度のシリカを得ることができる。
工程（Ｃ）は、工程（Ｂ）で得られたＳｉＯ２を含む固形分と鉱酸を混合して、ｐＨが３．０未満の酸性スラリーを調製し、上記固形分中に残存する不純物（例えば、Ａｌ、Ｆｅ）を溶解させた後、上記酸性スラリーを固液分離して、ＳｉＯ２を含む固形分と、不純物（例えば、Ａｌ、Ｆｅ）を含む液分を得る工程である。
本工程における酸性スラリーのｐＨは、３．０未満、好ましくは２．０以下である。酸性スラリーのｐＨを上記範囲内に調整して酸洗浄を行うことにより、工程（Ｂ）で得られた固形分にわずかに残存するアルミニウム分、鉄分等の不純物を溶解して液分中へ移行させることができ、固形分中のシリカ含有率を上昇させることができるため、さらに高純度のシリカを得ることができる。
ｐＨを上記数値範囲内に調整するための鉱酸としては、硫酸、塩酸、シュウ酸等が用いられる。
ｐＨ調整後、フィルタープレス等の固液分離手段を用いて、固形分と液分に分離する。
なお、本工程においてｐＨ調整を行う際の液温は、特に限定されるものではないが、エネルギーコストの観点から、好ましくは１０〜８０℃、より好ましくは１５〜４０℃、特に好ましくは２０℃〜３０℃であり、通常、常温（例えば１０〜４０℃）である。液温を上記範囲内とすることにより、処理効率を高めることができる。
また、酸洗浄工程後の液分を回収し、工程（Ｂ）に用いられる鉱酸、および工程（Ｃ）に用いられる鉱酸として再利用してもよい。
[Step (C); acid washing step]
The solid content containing SiO 2 obtained in the step (B) is high-purity silica in which impurities such as Al, Fe, Ti, B, and P are reduced.
The step (C) (acid cleaning step) can be appropriately performed on the solid content containing SiO 2 obtained in the step (B). By performing the acid washing step, higher purity silica can be obtained.
In step (C), the solid content containing SiO 2 obtained in step (B) and mineral acid are mixed to prepare an acidic slurry having a pH of less than 3.0, and impurities remaining in the solid content ( For example, after dissolving Al, Fe), the acidic slurry is subjected to solid-liquid separation to obtain a solid content containing SiO 2 and a liquid content containing impurities (for example, Al, Fe).
The pH of the acidic slurry in this step is less than 3.0, preferably 2.0 or less. By adjusting the pH of the acidic slurry to the above range and performing acid cleaning, impurities such as aluminum and iron remaining slightly in the solid content obtained in step (B) are dissolved and transferred into the liquid. Since the silica content in the solid content can be increased, silica with higher purity can be obtained.
As the mineral acid for adjusting the pH within the above numerical range, sulfuric acid, hydrochloric acid, oxalic acid and the like are used.
After the pH adjustment, the solid and liquid components are separated using a solid-liquid separation means such as a filter press.
In addition, although the liquid temperature at the time of adjusting pH in this process is not specifically limited, From a viewpoint of energy cost, Preferably it is 10-80 degreeC, More preferably, it is 15-40 degreeC, Most preferably, it is 20 degreeC. It is -30 degreeC and is normal temperature (for example, 10-40 degreeC) normally. By setting the liquid temperature within the above range, the processing efficiency can be increased.
Moreover, you may collect | recover the liquid components after an acid washing process, and may reuse as a mineral acid used for a process (B), and a mineral acid used for a process (C).
本発明では、工程（Ｂ）における過酸化水素の使用に代えて、または、工程（Ｂ）における過酸化水素の使用とともに、工程（Ｃ）において、鉱酸と過酸化水素を混合することで、不純物（特にＴｉ）が低減された高純度シリカを得ることができる。
混合方法は特に限定されるものではなく、（１）工程（Ｂ）で得られたＳｉＯ２を含む固形分と過酸化水素を混合し、次いで得られた混合物と鉱酸を混合する方法、（２）鉱酸と過酸化水素を混合し、次いで得られた混合物と工程（Ｂ）で得られたＳｉＯ２を含む固形分を混合する方法、（３）工程（Ｂ）で得られたＳｉＯ２を含む固形分と鉱酸を混合し、次いで得られた混合物と過酸化水素を混合する方法、（４）工程（Ｂ）で得られたＳｉＯ２を含む固形分と、鉱酸と、過酸化水素を同時に混合する方法が挙げられる。中でも、工程の上流側で不純物（特にＴｉ）の低減を図るという観点から（１）が好ましい。
過酸化水素の添加量は、シリカ（ＳｉＯ２）の質量（１００質量％）に対して、好ましくは０．１〜１５．０質量％、より好ましくは０．１〜１０．０質量％、特に好ましくは０．１〜５．０質量％である。過酸化水素の添加量が０．１質量％未満では不純物（例えばＴｉ）の低減効果が十分ではなく、１５．０質量％を超えると、不純物（例えばＴｉ）低減効果が飽和状態となる。
本発明においては、本明細書の段落００１４、及び、段落００１７に記載された方法に従い、工程（Ｂ）及び工程（Ｃ）の少なくともいずれか一方において過酸化水素を混合することで、本発明の効果を得ることができる。
In the present invention, in place of the use of hydrogen peroxide in the step (B) or together with the use of hydrogen peroxide in the step (B), in the step (C), the mineral acid and hydrogen peroxide are mixed, High purity silica with reduced impurities (particularly Ti) can be obtained.
The mixing method is not particularly limited, and (1) a method in which the solid content containing SiO 2 obtained in step (B) and hydrogen peroxide are mixed, and then the resulting mixture and mineral acid are mixed. 2) A method of mixing mineral acid and hydrogen peroxide, and then mixing the resulting mixture with the solid content containing SiO 2 obtained in step (B), (3) SiO 2 obtained in step (B). A method of mixing a solid content containing mineral and a mineral acid, and then mixing the resulting mixture and hydrogen peroxide, (4) a solid content containing SiO 2 obtained in step (B), a mineral acid, and peroxidation The method of mixing hydrogen simultaneously is mentioned. Among these, (1) is preferable from the viewpoint of reducing impurities (particularly Ti) on the upstream side of the process.
The amount of hydrogen peroxide added is preferably 0.1 to 15.0% by mass, more preferably 0.1 to 10.0% by mass, and particularly preferably 0.1% to 10.0% by mass with respect to the mass (100% by mass) of silica (SiO 2 ). Preferably it is 0.1-5.0 mass%. If the amount of hydrogen peroxide added is less than 0.1% by mass, the effect of reducing impurities (eg, Ti) is not sufficient, and if it exceeds 15.0% by mass, the effect of reducing impurities (eg, Ti) becomes saturated.
In the present invention, hydrogen peroxide is mixed in at least one of the step (B) and the step (C) according to the method described in paragraphs 0014 and 0017 of the present specification. An effect can be obtained.
［工程（Ｄ）；水洗浄工程］
本工程は、前工程（工程（Ｂ）または工程（Ｃ））で得られたＳｉＯ２を含む固形分に対して、適宜、水洗浄を行うことにより、より高純度のシリカを得る工程である。水洗浄を行うことにより、前工程で得られた固形分にわずかに残存するナトリウム、硫黄等の不純物を溶解して液分中へ移行させることができ、固形分中のシリカ含有率を上昇させることができるため、さらに高純度のシリカを得ることができる。
水洗浄後、フィルタープレス等の固液分離手段を用いて、固形分と液分に分離する。
また、水洗浄工程後の液分を回収し、工程（Ａ１）、工程（Ａ）、工程（Ｂ）、工程（Ｃ）、及び工程（Ｄ）に用いられる水として再利用してもよい。
[Step (D); water washing step]
This step is a step of obtaining higher-purity silica by appropriately washing the solid content containing SiO 2 obtained in the previous step (step (B) or step (C)). . By washing with water, impurities such as sodium and sulfur remaining slightly in the solid content obtained in the previous step can be dissolved and transferred into the liquid content, and the silica content in the solid content is increased. Therefore, silica with higher purity can be obtained.
After washing with water, the solid and liquid components are separated using a solid-liquid separation means such as a filter press.
Moreover, you may collect | recover the liquid components after a water washing process, and may reuse as water used for a process (A1), a process (A), a process (B), a process (C), and a process (D).
さらに、工程（Ａ）と工程（Ｂ）の間で、適宜、イオン交換処理及び／又は活性炭処理を行うことができる。
イオン交換処理及び／又は活性炭処理で回収される不純物は、ホウ素（Ｂ）、リン（Ｐ）、アルミニウム(Ａｌ)、鉄（Ｆｅ）、ナトリウム（Ｎａ）、チタン（Ｔｉ）、カルシウム（Ｃａ）、カリウム（Ｋ）、マグネシウム（Ｍｇ）、及び有機物（Ｃ）からなる群より選ばれる一種以上である。
イオン交換処理は、キレート樹脂、イオン交換樹脂等のイオン交換媒体を用いて行なうことができる。
イオン交換媒体の種類は、除去対象元素に対する選択性を考慮して、適宜定めればよい。例えば、ホウ素を除去する場合、グルカミン基を有するキレート樹脂や、Ｎ−メチルグルカミン基を有するイオン交換樹脂等を用いることができる。
イオン交換媒体の形態は、特に限定されるものではなく、ビーズ状、繊維状、クロス状等が挙げられる。イオン交換媒体への液分の通液方法もなんら限定されるものではなく、例えばカラムにキレート樹脂またはイオン交換樹脂を充填して連続的に通液する方法などを用いることができる。
イオン交換処理及び／又は活性炭処理を行う際の液温は、各処理に用いる材料の耐用温度以下であれば、特に限定されない。
Furthermore, an ion exchange treatment and / or an activated carbon treatment can be appropriately performed between the step (A) and the step (B).
Impurities recovered by ion exchange treatment and / or activated carbon treatment are boron (B), phosphorus (P), aluminum (Al), iron (Fe), sodium (Na), titanium (Ti), calcium (Ca), It is 1 or more types chosen from the group which consists of potassium (K), magnesium (Mg), and organic substance (C).
The ion exchange treatment can be performed using an ion exchange medium such as a chelate resin or an ion exchange resin.
The type of ion exchange medium may be appropriately determined in consideration of the selectivity with respect to the element to be removed. For example, when removing boron, a chelate resin having a glucamine group, an ion exchange resin having an N-methylglucamine group, or the like can be used.
The form of the ion exchange medium is not particularly limited, and examples thereof include beads, fibers, and cloths. The method for passing the liquid through the ion exchange medium is not limited at all, and for example, a method in which a column is filled with a chelate resin or an ion exchange resin and continuously passed can be used.
The liquid temperature at the time of performing an ion exchange process and / or activated carbon process will not be specifically limited if it is below the durable temperature of the material used for each process.
本発明の製造方法によって最終的に得られたシリカを含む固形分は、適宜、乾燥処理及び／又は焼成処理を行うことができる。乾燥処理及び／又は焼成処理の条件は、例えば、１００〜１０００℃で１〜５時間である。
また、最終的に得られたシリカを含む固形分をアルカリ溶液（例えば水酸化ナトリウム）に溶解させ、工程（Ｂ）のケイ酸アルカリ水溶液として用い、工程（Ｂ）から工程（Ｄ）を複数回繰り返すことによって、より高純度のシリカを得ることができる。
The solid content containing silica finally obtained by the production method of the present invention can be appropriately subjected to a drying treatment and / or a firing treatment. The conditions for the drying treatment and / or the firing treatment are, for example, 100 to 1000 ° C. and 1 to 5 hours.
Moreover, the solid content containing silica finally obtained is dissolved in an alkali solution (for example, sodium hydroxide) and used as the alkali silicate aqueous solution in the step (B), and the steps (B) to (D) are performed a plurality of times. By repeating, higher purity silica can be obtained.
本発明の製造方法で得られるシリカは、シリカの含有率が高く、またアルミニウム（Ａｌ）、鉄（Ｆｅ）、チタン（Ｔｉ）、ホウ素（Ｂ）、リン（Ｐ）等の不純物の含有量が低いものである。
本発明の製造方法で得られる高純度シリカ中のＳｉＯ２の含有率は、好ましくは９９．０質量％以上である。また、高純度シリカ中のＮａ、Ｓ、Ａｌ、Ｆｅ、Ｃａ、Ｂ、Ｐ、Ｔｉの含有率は、各々、好ましくは５．０ｐｐｍ以下、５．０ｐｐｍ以下、１．０ｐｐｍ以下、１．０ｐｐｍ以下、１．０ｐｐｍ以下、０．１ｐｐｍ以下、１.０ｐｐｍ以下、１．０ｐｐｍ以下である。
Silica obtained by the production method of the present invention has a high silica content, and also contains impurities such as aluminum (Al), iron (Fe), titanium (Ti), boron (B), and phosphorus (P). It is low.
The content of SiO 2 in the high-purity silica obtained by the production method of the present invention is preferably 99.0% by mass or more. Further, the content of Na, S, Al, Fe, Ca, B, P, and Ti in the high purity silica is preferably 5.0 ppm or less, 5.0 ppm or less, 1.0 ppm or less, 1.0 ppm or less, respectively. 1.0 ppm or less, 0.1 ppm or less, 1.0 ppm or less, or 1.0 ppm or less.
以下、本発明を実施例により具体的に説明するが、本発明はこれら実施例に限定されるものではない。
［実施例１］
水ガラス溶液（富士化学（株）製：ＳｉＯ２／Ｎａ２Ｏ（モル比）＝３．２０）１４０ｇに、水３５ｇを加えて混合し、次いで３５質量％の過酸化水素水４．７ｍｌを添加することによって、過酸化水素が添加されたＳｉ濃度１０．０質量％の水ガラス溶液を得た。
得られた水ガラス水溶液６６．２ｇを硫酸濃度１０．７体積％（水１６５．６ｍｌに濃硫酸２０ｍｌを混合したもの）の硫酸２００ｇ中に滴下し、常温（２５℃）下で沈降性シリカを析出させた後、減圧下でブフナー漏斗を用いて固液分離し、ＳｉＯ２を含む固形分（沈降性シリカ）１９．４ｇと、不純物を含む液分２４６．８ｇを得た。なお、ｐＨは滴下終了時まで１．０以下に保った。
得られたＳｉＯ２を含む固形分（沈降性シリカ）に対して、常温（２５℃）下で硫酸濃度１０．７体積％の硫酸を２００ｇ添加してｐＨが３．０未満のスラリーとした。このスラリーを固液分離した後に、得られた固形分を蒸留水を用いて水洗した。その後、１０５℃で１日乾燥させ、精製シリカ９．７ｇを得た。
得られた精製シリカ中のチタン（Ｔｉ）の濃度を測定した。その結果を表１に示す。
なお、表１中、「過酸化水素の添加量」は、ＳｉＯ２の質量（１００質量％）に対する過酸化水素水中の過酸化水素（Ｈ２Ｏ２）の量（質量％）を示す。
得られた精製シリカは、乾燥後に、ＳｉＯ２：９９．９９９質量％、Ｎａ：２．１ｐｐｍ、Ｓ：検出限界未満（３．３ｐｐｍ未満）、Ａｌ：検出限界未満（０．５ｐｐｍ未満）、Ｆｅ：０．７ｐｐｍ、Ｃａ：検出限界未満（０．５ｐｐｍ未満）、Ｂ：検出限界未満（０．０５ｐｐｍ未満）、Ｐ：検出限界未満（１．０ｐｐｍ未満）の成分組成を有していた。また、Ｓｉの回収率は６５％であった。
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
[Example 1]
To 140 g of a water glass solution (Fuji Chemical Co., Ltd .: SiO 2 / Na 2 O (molar ratio) = 3.20), 35 g of water was added and mixed, and then 4.7 ml of 35 mass% hydrogen peroxide water was added. By adding, a water glass solution having a Si concentration of 10.0% by mass to which hydrogen peroxide was added was obtained.
66.2 g of the aqueous water glass solution thus obtained was dropped into 200 g of sulfuric acid having a sulfuric acid concentration of 10.7% by volume (165.6 ml of water mixed with 20 ml of concentrated sulfuric acid), and precipitated silica was added at room temperature (25 ° C.). After precipitation, solid-liquid separation was performed using a Buchner funnel under reduced pressure to obtain 19.4 g of a solid content (precipitating silica) containing SiO 2 and 246.8 g of a liquid content containing impurities. The pH was kept at 1.0 or less until the end of dropping.
200 g of sulfuric acid having a sulfuric acid concentration of 10.7 vol% was added to the solid content (precipitating silica) containing SiO 2 at room temperature (25 ° C.) to obtain a slurry having a pH of less than 3.0. The slurry was subjected to solid-liquid separation, and the obtained solid content was washed with distilled water. Thereafter, it was dried at 105 ° C. for 1 day to obtain 9.7 g of purified silica.
The concentration of titanium (Ti) in the obtained purified silica was measured. The results are shown in Table 1.
In Table 1, “amount of hydrogen peroxide added” indicates the amount (mass%) of hydrogen peroxide (H 2 O 2 ) in the hydrogen peroxide water with respect to the mass of SiO 2 (100 mass%).
The obtained purified silica is, after drying, SiO 2 : 99.999% by mass, Na: 2.1 ppm, S: less than detection limit (less than 3.3 ppm), Al: less than detection limit (less than 0.5 ppm), Fe : 0.7 ppm, Ca: less than detection limit (less than 0.5 ppm), B: less than detection limit (less than 0.05 ppm), P: less than detection limit (less than 1.0 ppm). Moreover, the recovery rate of Si was 65%.
［実施例２］
３５質量％の過酸化水素水の添加量を４．７ｍｌから３．４ｍｌに変更する以外は実施例１と同様にして精製シリカ１０．０ｇを得た。
得られた精製シリカ中のチタン（Ｔｉ）の濃度を測定した。その結果を表１に示す。
得られた精製シリカは、乾燥後に、ＳｉＯ２：９９．９９９質量％、Ｎａ：３．６ｐｐｍ、Ｓ：検出限界未満（３．３ｐｐｍ未満）、Ａｌ：検出限界未満（０．５ｐｐｍ未満）、Ｆｅ：０．６ｐｐｍ、Ｃａ：検出限界未満（０．５ｐｐｍ未満）、Ｂ：検出限界未満（０．０５ｐｐｍ未満）、Ｐ：検出限界未満（１．０ｐｐｍ未満）の成分組成を有していた。また、Ｓｉの回収率は６７％であった。
[Example 2]
10.0 g of purified silica was obtained in the same manner as in Example 1 except that the addition amount of the 35 mass% hydrogen peroxide solution was changed from 4.7 ml to 3.4 ml.
The concentration of titanium (Ti) in the obtained purified silica was measured. The results are shown in Table 1.
The obtained purified silica is, after drying, SiO 2 : 99.999% by mass, Na: 3.6 ppm, S: less than detection limit (less than 3.3 ppm), Al: less than detection limit (less than 0.5 ppm), Fe : 0.6 ppm, Ca: less than detection limit (less than 0.5 ppm), B: less than detection limit (less than 0.05 ppm), P: less than detection limit (less than 1.0 ppm). Moreover, the recovery rate of Si was 67%.
［実施例３］
３５質量％の過酸化水素水の添加量を４．７ｍｌから２．１ｍｌに変更する以外は実施例１と同様にして精製シリカ１０．０ｇを得た。
得られた精製シリカ中のチタン（Ｔｉ）の濃度を測定した。その結果を表１に示す。
得られた精製シリカは、乾燥後に、ＳｉＯ２：９９．９９９質量％、Ｎａ：３．９ｐｐｍ、Ｓ：検出限界未満（３．３ｐｐｍ未満）、Ａｌ：検出限界未満（０．５ｐｐｍ未満）、Ｆｅ：０．８ｐｐｍ、Ｃａ：０．６ｐｐｍ、Ｂ：検出限界未満（０．０５ｐｐｍ未満）、Ｐ：検出限界未満（１．０ｐｐｍ未満）の成分組成を有していた。また、Ｓｉの回収率は６７％であった。
[Example 3]
10.0 g of purified silica was obtained in the same manner as in Example 1 except that the addition amount of 35% by mass of hydrogen peroxide was changed from 4.7 ml to 2.1 ml.
The concentration of titanium (Ti) in the obtained purified silica was measured. The results are shown in Table 1.
The obtained purified silica is, after drying, SiO 2 : 99.999 mass%, Na: 3.9 ppm, S: less than detection limit (less than 3.3 ppm), Al: less than detection limit (less than 0.5 ppm), Fe : 0.8 ppm, Ca: 0.6 ppm, B: Less than detection limit (less than 0.05 ppm), P: Less than detection limit (less than 1.0 ppm). Moreover, the recovery rate of Si was 67%.
［実施例４］
３５質量％の過酸化水素水の添加量を４．７ｍｌから１．１ｍｌに変更する以外は実施例１と同様にして精製シリカ９．９ｇを得た。
得られた精製シリカ中のチタン（Ｔｉ）の濃度を測定した。その結果を表１に示す。
得られた精製シリカは、乾燥後に、ＳｉＯ２：９９．９９９質量％、Ｎａ：２．０ｐｐｍ、Ｓ：検出限界未満（３．３ｐｐｍ未満）、Ａｌ：検出限界未満（０．５ｐｐｍ未満）、Ｆｅ：０．９ｐｐｍ、Ｃａ：検出限界未満（０．５ｐｐｍ未満）、Ｂ：検出限界未満（０．０５ｐｐｍ未満）、Ｐ：検出限界未満（１．０ｐｐｍ未満）の成分組成を有していた。また、Ｓｉの回収率は６７％であった。
[Example 4]
9.9 g of purified silica was obtained in the same manner as in Example 1 except that the addition amount of 35% by mass hydrogen peroxide was changed from 4.7 ml to 1.1 ml.
The concentration of titanium (Ti) in the obtained purified silica was measured. The results are shown in Table 1.
The obtained purified silica is, after drying, SiO 2 : 99.999% by mass, Na: 2.0 ppm, S: less than detection limit (less than 3.3 ppm), Al: less than detection limit (less than 0.5 ppm), Fe : 0.9 ppm, Ca: less than detection limit (less than 0.5 ppm), B: less than detection limit (less than 0.05 ppm), P: less than detection limit (less than 1.0 ppm). Moreover, the recovery rate of Si was 67%.
［実施例５］
３５質量％の過酸化水素水の添加量を４．７ｍｌから０．２ｍｌに変更する以外は実施例１と同様にして精製シリカ１０．０ｇを得た。
得られた精製シリカ中のチタン（Ｔｉ）の濃度を測定した。その結果を表１に示す。
得られた精製シリカは、乾燥後に、ＳｉＯ２：９９．９９９質量％、Ｎａ：１．５ｐｐｍ、Ｓ：検出限界未満（３．３ｐｐｍ未満）、Ａｌ：検出限界未満（０．５ｐｐｍ未満）、Ｆｅ：０．５ｐｐｍ、Ｃａ：検出限界未満（０．５ｐｐｍ未満）、Ｂ：検出限界未満（０．０５ｐｐｍ未満）、Ｐ：検出限界未満（１．０ｐｐｍ未満）の成分組成を有していた。また、Ｓｉの回収率は６７％であった。
[Example 5]
10.0 g of purified silica was obtained in the same manner as in Example 1 except that the addition amount of 35% by mass of hydrogen peroxide was changed from 4.7 ml to 0.2 ml.
The concentration of titanium (Ti) in the obtained purified silica was measured. The results are shown in Table 1.
The obtained purified silica is, after drying, SiO 2 : 99.999 mass%, Na: 1.5 ppm, S: less than detection limit (less than 3.3 ppm), Al: less than detection limit (less than 0.5 ppm), Fe : 0.5 ppm, Ca: less than detection limit (less than 0.5 ppm), B: less than detection limit (less than 0.05 ppm), P: less than detection limit (less than 1.0 ppm). Moreover, the recovery rate of Si was 67%.
［実施例６］
水ガラス溶液（富士化学（株）製：ＳｉＯ２／Ｎａ２Ｏ（モル比）＝３．２０）１４０ｇに水３５ｇを加えて、Ｓｉ濃度１０．０質量％の水ガラス溶液を得た。
一方、水１６５．６ｍｌに濃硫酸２０ｍｌを加えて混合し、次いで３５質量％の過酸化水素水１．０ｍｌを添加することによって、過酸化水素が添加された硫酸濃度１０．７体積％の鉱酸を得た。
前記Ｓｉ濃度１０．０質量％の水ガラス溶液６６．２ｇを前記鉱酸に滴下し、常温（２５℃）下で沈降性シリカを析出させた後、減圧下でブフナー漏斗を用いて固液分離し、ＳｉＯ２を含む固形分（沈降性シリカ）１９．９ｇと、不純物を含む液分２４６．３ｇを得た。なお、ｐＨは滴下終了時まで１．０以下に保った。
得られたＳｉＯ２を含む固形分（沈降性シリカ）に対して、常温（２５℃）下で硫酸濃度１０．７体積％の硫酸を２００ｇ添加してｐＨが３．０未満のスラリーとした。このスラリーを固液分離した後に、得られた固形分を、蒸留水を用いて水洗した。その後、１０５℃で１日乾燥させ、精製シリカ９．９ｇを得た。
得られた精製シリカ中のチタン（Ｔｉ）の濃度を測定した。その結果を表１に示す。
得られた精製シリカは、乾燥後に、ＳｉＯ２：９９．９９９質量％、Ｎａ：１．７ｐｐｍ、Ｓ：検出限界未満（３．３ｐｐｍ未満）、Ａｌ：検出限界未満（０．５ｐｐｍ未満）、Ｆｅ：０．９ｐｐｍ、Ｃａ：検出限界未満（０．５ｐｐｍ未満）、Ｂ：検出限界未満（０．０５ｐｐｍ未満）、Ｐ：検出限界未満（１．０ｐｐｍ未満）の成分組成を有していた。また、Ｓｉの回収率は６６％であった。
[Example 6]
35 g of water was added to 140 g of a water glass solution (Fuji Chemical Co., Ltd. product: SiO 2 / Na 2 O (molar ratio) = 3.20) to obtain a water glass solution having a Si concentration of 10.0% by mass.
On the other hand, 20 ml of concentrated sulfuric acid was added to 165.6 ml of water and mixed, and then 1.0 ml of 35% by weight hydrogen peroxide solution was added, so that a mineral having a sulfuric acid concentration of 10.7% by volume added with hydrogen peroxide was added. The acid was obtained.
66.2 g of a water glass solution having a Si concentration of 10.0% by mass was dropped into the mineral acid, and precipitated silica was precipitated at room temperature (25 ° C.), followed by solid-liquid separation using a Buchner funnel under reduced pressure. As a result, 19.9 g of a solid content containing SiO 2 (precipitating silica) and 246.3 g of a liquid content containing impurities were obtained. The pH was kept at 1.0 or less until the end of dropping.
200 g of sulfuric acid having a sulfuric acid concentration of 10.7 vol% was added to the solid content (precipitating silica) containing SiO 2 at room temperature (25 ° C.) to obtain a slurry having a pH of less than 3.0. After this slurry was subjected to solid-liquid separation, the obtained solid content was washed with distilled water. Then, it was dried at 105 ° C. for 1 day to obtain 9.9 g of purified silica.
The concentration of titanium (Ti) in the obtained purified silica was measured. The results are shown in Table 1.
The obtained purified silica is, after drying, SiO 2 : 99.999% by mass, Na: 1.7 ppm, S: less than detection limit (less than 3.3 ppm), Al: less than detection limit (less than 0.5 ppm), Fe : 0.9 ppm, Ca: less than detection limit (less than 0.5 ppm), B: less than detection limit (less than 0.05 ppm), P: less than detection limit (less than 1.0 ppm). Further, the recovery rate of Si was 66%.
［実施例７］
水の量を１６５．６ｍｌから１６６．１ｍｌに変更し、かつ、３５質量％の過酸化水素水の添加量を１．０ｍｌから０．５ｍｌに変更する以外は実施例６と同様にして精製シリカ１０．０ｇを得た。
得られた精製シリカ中のチタン（Ｔｉ）の濃度を測定した。その結果を表１に示す。
得られた精製シリカは、乾燥後に、ＳｉＯ２：９９．９９９質量％、Ｎａ：２．５ｐｐｍ、Ｓ：検出限界未満（３．３ｐｐｍ未満）、Ａｌ：検出限界未満（０．５ｐｐｍ未満）、Ｆｅ：０．８ｐｐｍ、Ｃａ：検出限界未満（０．５ｐｐｍ未満）、Ｂ：検出限界未満（０．０５ｐｐｍ未満）、Ｐ：検出限界未満（１．０ｐｐｍ未満）の成分組成を有していた。また、Ｓｉの回収率は６７％であった。
[Example 7]
Purified silica in the same manner as in Example 6 except that the amount of water was changed from 165.6 ml to 166.1 ml, and the addition amount of 35% by mass hydrogen peroxide was changed from 1.0 ml to 0.5 ml. 10.0 g was obtained.
The concentration of titanium (Ti) in the obtained purified silica was measured. The results are shown in Table 1.
The obtained purified silica is, after drying, SiO 2 : 99.999% by mass, Na: 2.5 ppm, S: less than detection limit (less than 3.3 ppm), Al: less than detection limit (less than 0.5 ppm), Fe : 0.8 ppm, Ca: less than detection limit (less than 0.5 ppm), B: less than detection limit (less than 0.05 ppm), P: less than detection limit (less than 1.0 ppm). Moreover, the recovery rate of Si was 67%.
［実施例８］
水の量を１６５．６ｍｌから１６６．５ｍｌに変更し、かつ、３５質量％の過酸化水素水の添加量を１．０ｍｌから０．１ｍｌに変更する以外は実施例６と同様にして精製シリカ１０．０ｇを得た。
得られた精製シリカ中のチタン（Ｔｉ）の濃度を測定した。その結果を表１に示す。
得られた精製シリカは、乾燥後に、ＳｉＯ２：９９．９９９質量％、Ｎａ：２．４ｐｐｍ、Ｓ：検出限界未満（３．３ｐｐｍ未満）、Ａｌ：検出限界未満（０．５ｐｐｍ未満）、Ｆｅ：０．７ｐｐｍ、Ｃａ：検出限界未満（０．５ｐｐｍ未満）、Ｂ：検出限界未満（０．０５ｐｐｍ未満）、Ｐ：検出限界未満（１．０ｐｐｍ未満）の成分組成を有していた。また、Ｓｉの回収率は６７％であった。
[Example 8]
Purified silica in the same manner as in Example 6 except that the amount of water was changed from 165.6 ml to 166.5 ml, and the addition amount of 35% by mass hydrogen peroxide was changed from 1.0 ml to 0.1 ml. 10.0 g was obtained.
The concentration of titanium (Ti) in the obtained purified silica was measured. The results are shown in Table 1.
The obtained purified silica is, after drying, SiO 2 : 99.999% by mass, Na: 2.4 ppm, S: less than detection limit (less than 3.3 ppm), Al: less than detection limit (less than 0.5 ppm), Fe : 0.7 ppm, Ca: less than detection limit (less than 0.5 ppm), B: less than detection limit (less than 0.05 ppm), P: less than detection limit (less than 1.0 ppm). Moreover, the recovery rate of Si was 67%.
［実施例９］
水ガラス溶液（富士化学（株）製：ＳｉＯ２／Ｎａ２Ｏ（モル比）＝３．２０）１４０ｇに水３５ｇを加えて、Ｓｉ濃度１０．０質量％の水ガラス溶液を得た。
得られた水ガラス水溶液６６．２ｇを硫酸濃度１０．７体積％の硫酸２００ｇ中に滴下し、常温（２５℃）下で沈降性シリカを析出させた後、減圧下でブフナー漏斗を用いて固液分離し、ＳｉＯ２を含む固形分（沈降性シリカ）１９．４ｇと、不純物を含む液分２４６．８ｇを得た。なお、ｐＨは滴下終了時まで１．０以下に保った。
一方、水１６５．６ｍｌに濃硫酸２０ｍｌを加えて混合し、次いで３５質量％の過酸化水素水１．０ｍｌを添加することによって硫酸濃度１０．７体積％の鉱酸を得た。この鉱酸を常温（２５℃）下で前記の固形分（沈降性シリカ）に対して、２００ｇ添加してｐＨが３．０未満のスラリーとした。このスラリーを固液分離した後に、得られた固形分を、蒸留水を用いて水洗した。その後、１０５℃で１日乾燥させ、精製シリカ９．７ｇを得た。
得られた精製シリカ中のチタン（Ｔｉ）の濃度を測定した。その結果を表１に示す。
得られた精製シリカは、乾燥後に、ＳｉＯ２：９９．９９９質量％、Ｎａ：２．０ｐｐｍ、Ｓ：検出限界未満（３．３ｐｐｍ未満）、Ａｌ：０．５ｐｐｍ、Ｆｅ：０．８ｐｐｍ、Ｃａ：０．５ｐｐｍ、Ｂ：検出限界未満（０．０５ｐｐｍ未満）、Ｐ：検出限界未満（１．０ｐｐｍ未満）の成分組成を有していた。また、Ｓｉの回収率は６５％であった。
[Example 9]
35 g of water was added to 140 g of a water glass solution (Fuji Chemical Co., Ltd. product: SiO 2 / Na 2 O (molar ratio) = 3.20) to obtain a water glass solution having a Si concentration of 10.0% by mass.
66.2 g of the aqueous water glass solution thus obtained was dropped into 200 g of sulfuric acid having a sulfuric acid concentration of 10.7% by volume, and precipitated silica was precipitated at room temperature (25 ° C.), and then solidified using a Buchner funnel under reduced pressure. Liquid separation was performed to obtain 19.4 g of a solid content (precipitating silica) containing SiO 2 and 246.8 g of a liquid content containing impurities. The pH was kept at 1.0 or less until the end of dropping.
On the other hand, 20 ml of concentrated sulfuric acid was added to 165.6 ml of water and mixed, and then 1.0 ml of 35% by mass hydrogen peroxide solution was added to obtain a mineral acid having a sulfuric acid concentration of 10.7% by volume. 200 g of this mineral acid was added to the solid content (precipitating silica) at room temperature (25 ° C.) to obtain a slurry having a pH of less than 3.0. After this slurry was subjected to solid-liquid separation, the obtained solid content was washed with distilled water. Thereafter, it was dried at 105 ° C. for 1 day to obtain 9.7 g of purified silica.
The concentration of titanium (Ti) in the obtained purified silica was measured. The results are shown in Table 1.
The obtained purified silica is, after drying, SiO 2 : 99.999 mass%, Na: 2.0 ppm, S: less than detection limit (less than 3.3 ppm), Al: 0.5 ppm, Fe: 0.8 ppm, Ca : 0.5 ppm, B: less than detection limit (less than 0.05 ppm), P: less than detection limit (less than 1.0 ppm). Moreover, the recovery rate of Si was 65%.
［実施例１０］
水の量を１６５．６ｍｌから１６６．１ｍｌに変更し、かつ、３５質量％の過酸化水素水の添加量を１．０ｍｌから０．５ｍｌに変更する以外は実施例９と同様にして精製シリカ１０．０ｇを得た。
得られた精製シリカ中のチタン（Ｔｉ）の濃度を測定した。その結果を表１に示す。
得られた精製シリカは、乾燥後に、ＳｉＯ２：９９．９９９質量％、Ｎａ：１．９ｐｐｍ、Ｓ：検出限界未満（３．３ｐｐｍ未満）、Ａｌ：検出限界未満（０．５ｐｐｍ未満）、Ｆｅ：０．９ｐｐｍ、Ｃａ：検出限界未満（０．５ｐｐｍ未満）、Ｂ：検出限界未満（０．０５ｐｐｍ未満）、Ｐ：検出限界未満（１．０ｐｐｍ未満）の成分組成を有していた。また、Ｓｉの回収率は６７％であった。
[Example 10]
Purified silica in the same manner as in Example 9 except that the amount of water was changed from 165.6 ml to 166.1 ml, and the addition amount of 35% by mass hydrogen peroxide was changed from 1.0 ml to 0.5 ml. 10.0 g was obtained.
The concentration of titanium (Ti) in the obtained purified silica was measured. The results are shown in Table 1.
The obtained purified silica is, after drying, SiO 2 : 99.999 mass%, Na: 1.9 ppm, S: less than detection limit (less than 3.3 ppm), Al: less than detection limit (less than 0.5 ppm), Fe : 0.9 ppm, Ca: less than detection limit (less than 0.5 ppm), B: less than detection limit (less than 0.05 ppm), P: less than detection limit (less than 1.0 ppm). Moreover, the recovery rate of Si was 67%.
［実施例１１］
水の量を１６５．６ｍｌから１６６．５ｍｌに変更し、かつ、３５質量％の過酸化水素水の添加量を１．０ｍｌから０．１ｍｌに変更する以外は実施例９と同様にして精製シリカ１０．０ｇを得た。
得られた精製シリカ中のチタン（Ｔｉ）の濃度を測定した。その結果を表１に示す。
得られた精製シリカは、乾燥後に、ＳｉＯ２：９９．９９９質量％、Ｎａ：１．８ｐｐｍ、Ｓ：検出限界未満（３．３ｐｐｍ未満）、Ａｌ：検出限界未満（０．５ｐｐｍ未満）、Ｆｅ：１．０ｐｐｍ、Ｃａ：検出限界未満（０．５ｐｐｍ未満）、Ｂ：検出限界未満（０．０５ｐｐｍ未満）、Ｐ：検出限界未満（１．０ｐｐｍ未満）の成分組成を有していた。また、Ｓｉの回収率は６７％であった。
[Example 11]
Purified silica in the same manner as in Example 9 except that the amount of water was changed from 165.6 ml to 166.5 ml and the addition amount of 35% by mass hydrogen peroxide was changed from 1.0 ml to 0.1 ml. 10.0 g was obtained.
The concentration of titanium (Ti) in the obtained purified silica was measured. The results are shown in Table 1.
The obtained purified silica is, after drying, SiO 2 : 99.999 mass%, Na: 1.8 ppm, S: less than detection limit (less than 3.3 ppm), Al: less than detection limit (less than 0.5 ppm), Fe : 1.0 ppm, Ca: less than detection limit (less than 0.5 ppm), B: less than detection limit (less than 0.05 ppm), P: less than detection limit (less than 1.0 ppm). Moreover, the recovery rate of Si was 67%.
［実施例１２］
３５質量％の過酸化水素水の添加量を４．７ｍｌから１．１ｍｌに変更し、かつ、蒸留水を用いた水洗を行わない以外は実施例１と同様にして精製シリカ９．８ｇを得た。
得られた精製シリカ中のチタン（Ｔｉ）の濃度を測定した。その結果を表１に示す。
得られた精製シリカは、乾燥後に、Ｎａ：３１０ｐｐｍ、Ｓ：４２５ｐｐｍ、Ａｌ：０．９ｐｐｍ、Ｆｅ：０．９ｐｐｍ、Ｃａ：１．０ｐｐｍ、Ｂ：検出限界未満（０．０５ｐｐｍ未満）、Ｐ：検出限界未満（１．０ｐｐｍ未満）の成分組成を有していた。また、Ｓｉの回収率は６６％であった。
[Example 12]
9.8 g of purified silica was obtained in the same manner as in Example 1 except that the addition amount of 35% by mass of hydrogen peroxide was changed from 4.7 ml to 1.1 ml and no washing with distilled water was performed. It was.
The concentration of titanium (Ti) in the obtained purified silica was measured. The results are shown in Table 1.
The obtained purified silica, after drying , Na: 310 ppm, S: 425 ppm, Al: 0.9 ppm, Fe: 0.9 ppm, Ca: 1.0 ppm, B: less than detection limit (less than 0.05 ppm), P: It had a component composition below the detection limit (less than 1.0 ppm). Further, the recovery rate of Si was 66%.
［実施例１３］
水ガラス溶液（富士化学（株）製：ＳｉＯ２／Ｎａ２Ｏ（モル比）＝３．２０）１４０ｇに、水３５ｇを加えて混合し、次いで３５質量％の過酸化水素水１．１ｍｌを添加することによって、過酸化水素が添加されたＳｉ濃度１０．０質量％の水ガラス溶液を得た。
得られた水ガラス水溶液６６．２ｇを硫酸濃度１０．７体積％（水１６５．６ｍｌに濃硫酸２０ｍｌを混合したもの）の硫酸２００ｇ中に滴下し、常温（２５℃）下で沈降性シリカを析出させた後、減圧下でブフナー漏斗を用いて固液分離し、ＳｉＯ２を含む固形分（沈降性シリカ）１９．５ｇと、不純物を含む液分２４６．７ｇを得た。なお、ｐＨは滴下終了時まで１．０以下に保った。
得られたＳｉＯ２を含む固形分（沈降性シリカ）を蒸留水を用いて水洗した。その後、１０５℃で１日乾燥させ、精製シリカ９．７ｇを得た。
得られた精製シリカ中のチタン（Ｔｉ）の濃度を測定した。その結果を表１に示す。
得られた精製シリカは、乾燥後に、ＳｉＯ２：９９．９９９質量％、Ｎａ：２．０ｐｐｍ、Ｓ：検出限界未満（３．３ｐｐｍ未満）、Ａｌ：３．９ｐｐｍ、Ｆｅ：４．０ｐｐｍ、Ｃａ：１．１ｐｐｍ、Ｂ：０．１ｐｐｍ、Ｐ：１．２ｐｐｍの成分組成を有していた。また、Ｓｉの回収率は６５％であった。
[Example 13]
To 140 g of a water glass solution (Fuji Chemical Co., Ltd .: SiO 2 / Na 2 O (molar ratio) = 3.20) 35 g of water was added and mixed, and then 1.1 ml of 35% by mass hydrogen peroxide was added. By adding, a water glass solution having a Si concentration of 10.0% by mass to which hydrogen peroxide was added was obtained.
66.2 g of the aqueous water glass solution thus obtained was dropped into 200 g of sulfuric acid having a sulfuric acid concentration of 10.7% by volume (165.6 ml of water mixed with 20 ml of concentrated sulfuric acid), and precipitated silica was added at room temperature (25 ° C.). After precipitation, solid-liquid separation was performed using a Buchner funnel under reduced pressure to obtain 19.5 g of a solid content (precipitating silica) containing SiO 2 and 246.7 g of a liquid content containing impurities. The pH was kept at 1.0 or less until the end of dropping.
The obtained solid content (precipitating silica) containing SiO 2 was washed with distilled water. Thereafter, it was dried at 105 ° C. for 1 day to obtain 9.7 g of purified silica.
The concentration of titanium (Ti) in the obtained purified silica was measured. The results are shown in Table 1.
The obtained purified silica is, after drying, SiO 2 : 99.999 mass%, Na: 2.0 ppm, S: less than detection limit (less than 3.3 ppm), Al: 3.9 ppm, Fe: 4.0 ppm, Ca : 1.1 ppm, B: 0.1 ppm, P: 1.2 ppm. Moreover, the recovery rate of Si was 65%.
［実施例１４］
水ガラス溶液（富士化学（株）製：ＳｉＯ２／Ｎａ２Ｏ（モル比）＝３．２０）１４０ｇに、水３５ｇを加えて混合し、次いで３５質量％の過酸化水素水１．１ｍｌを添加することによって、過酸化水素が添加されたＳｉ濃度１０．０質量％の水ガラス溶液を得た。
得られた水ガラス水溶液６６．２ｇを硫酸濃度１０．７体積％の硫酸２００ｇ中に滴下し、常温（２５℃）下で沈降性シリカを析出させた後、減圧下でブフナー漏斗を用いて固液分離し、ＳｉＯ２を含む固形分（沈降性シリカ）１９．４ｇと、不純物を含む液分２４６．８ｇを得た。なお、ｐＨは滴下終了時まで１．０以下に保った。その後、１０５℃で１日乾燥させ、精製シリカ９．７ｇを得た。
得られた精製シリカ中のチタン（Ｔｉ）の濃度を測定した。その結果を表１に示す。
得られた精製シリカは、乾燥後に、Ｎａ：２４６ｐｐｍ、Ｓ：３０８ｐｐｍ、Ａｌ：９．５ｐｐｍ、Ｆｅ：８．２ｐｐｍ、Ｃａ：２．６ｐｐｍ、Ｂ：０．５ｐｐｍ、Ｐ：１．３ｐｐｍの成分組成を有していた。また、Ｓｉの回収率は６５％であった。
[Example 14]
To 140 g of a water glass solution (Fuji Chemical Co., Ltd .: SiO 2 / Na 2 O (molar ratio) = 3.20) 35 g of water was added and mixed, and then 1.1 ml of 35% by mass hydrogen peroxide was added. By adding, a water glass solution having a Si concentration of 10.0% by mass to which hydrogen peroxide was added was obtained.
66.2 g of the aqueous water glass solution thus obtained was dropped into 200 g of sulfuric acid having a sulfuric acid concentration of 10.7% by volume, and precipitated silica was precipitated at room temperature (25 ° C.), and then solidified using a Buchner funnel under reduced pressure. Liquid separation was performed to obtain 19.4 g of a solid content (precipitating silica) containing SiO 2 and 246.8 g of a liquid content containing impurities. The pH was kept at 1.0 or less until the end of dropping. Thereafter, it was dried at 105 ° C. for 1 day to obtain 9.7 g of purified silica.
The concentration of titanium (Ti) in the obtained purified silica was measured. The results are shown in Table 1.
The obtained purified silica was dried, and Na: 246 ppm, S: 308 ppm, Al: 9.5 ppm, Fe: 8.2 ppm, Ca: 2.6 ppm, B: 0.5 ppm, P: 1.3 ppm Had. Moreover, the recovery rate of Si was 65%.
［実施例１５］
水ガラス溶液（富士化学（株）製：ＳｉＯ２／Ｎａ２Ｏ（モル比）＝３．２０）１００ｇに含まれる水分を乾燥機にて蒸発させて、Ｓｉ濃度１６．４質量％に調製した水ガラス溶液８０．５ｇを得た。次いで３５質量％の過酸化水素水０．８ｍｌを添加することによって、過酸化水素が添加されたＳｉ濃度１６．４質量％の水ガラス溶液を得た。
得られた水ガラス水溶液６６．２ｇを硫酸濃度１０．７体積％の硫酸２００ｇ中に滴下し、常温（２５℃）下で沈降性シリカを析出させた後、減圧下でブフナー漏斗を用いて固液分離し、ＳｉＯ２を含む固形分（沈降性シリカ）４７ｇと、不純物を含む液分２１９ｇを得た。なお、ｐＨは滴下終了時まで１．０以下に保った。
得られたＳｉＯ２を含む固形分（沈降性シリカ）に対して、常温（２５℃）下で硫酸濃度１０．７体積％の硫酸を２００ｇ添加してｐＨが３．０未満のスラリーとした。このスラリーを固液分離した後に、得られた固形分を蒸留水を用いて水洗した。その後、１０５℃で１日乾燥させ、精製シリカ２３．２ｇを得た。
得られた精製シリカ中のチタン（Ｔｉ）の濃度を測定した。その結果を表１に示す。
得られた精製シリカは、乾燥後に、ＳｉＯ２：９９．９質量％、Ｎａ：２０５ｐｐｍ、Ｓ：３５４ｐｐｍ、Ａｌ：１．８ｐｐｍ、Ｆｅ：２．２ｐｐｍ、Ｃａ：１．３ｐｐｍ、Ｂ：０．６ｐｐｍ、Ｐ：１．２ｐｐｍの成分組成を有していた。また、Ｓｉの回収率は６５％であった。
[Example 15]
Water contained in 100 g of a water glass solution (Fuji Chemical Co., Ltd .: SiO 2 / Na 2 O (molar ratio) = 3.20) was evaporated in a dryer to prepare a Si concentration of 16.4% by mass. 80.5 g of a water glass solution was obtained. Subsequently, 0.8 ml of 35 mass% hydrogen peroxide water was added to obtain a water glass solution having a Si concentration of 16.4 mass% to which hydrogen peroxide was added.
66.2 g of the aqueous water glass solution thus obtained was dropped into 200 g of sulfuric acid having a sulfuric acid concentration of 10.7% by volume, and precipitated silica was precipitated at room temperature (25 ° C.), and then solidified using a Buchner funnel under reduced pressure. Liquid separation was performed to obtain 47 g of a solid content (precipitating silica) containing SiO 2 and 219 g of a liquid content containing impurities. The pH was kept at 1.0 or less until the end of dropping.
200 g of sulfuric acid having a sulfuric acid concentration of 10.7 vol% was added to the solid content (precipitating silica) containing SiO 2 at room temperature (25 ° C.) to obtain a slurry having a pH of less than 3.0. The slurry was subjected to solid-liquid separation, and the obtained solid content was washed with distilled water. Then, it was dried at 105 ° C. for 1 day to obtain 23.2 g of purified silica.
The concentration of titanium (Ti) in the obtained purified silica was measured. The results are shown in Table 1.
The obtained purified silica is, after drying, SiO 2 : 99.9% by mass, Na: 205 ppm, S: 354 ppm, Al: 1.8 ppm, Fe: 2.2 ppm, Ca: 1.3 ppm, B: 0.6 ppm , P: It had a component composition of 1.2 ppm. Moreover, the recovery rate of Si was 65%.
［実施例１６］
３５質量％の過酸化水素水の添加量を４．７ｍｌから１．１ｍｌに変更し、かつ、ｐＨを滴下終了時まで２．０に保った以外は実施例１と同様にして精製シリカ９．８ｇを得た。
得られた精製シリカ中のチタン（Ｔｉ）の濃度を測定した。その結果を表１に示す。
得られた精製シリカは、乾燥後に、Ｎａ：６２ｐｐｍ、Ｓ：９１ｐｐｍ、Ａｌ：検出限界未満（０．５ｐｐｍ未満）、Ｆｅ：０．９ｐｐｍ、Ｃａ：検出限界未満（０．５ｐｐｍ未満）、Ｂ：検出限界未満（０．０５ｐｐｍ未満）、Ｐ：検出限界未満（１．０ｐｐｍ未満）の成分組成を有していた。また、Ｓｉの回収率は６６％であった。
[Example 16]
Purified silica in the same manner as in Example 1 except that the addition amount of 35% by mass of hydrogen peroxide was changed from 4.7 ml to 1.1 ml and the pH was kept at 2.0 until the end of dropping. 8 g was obtained.
The concentration of titanium (Ti) in the obtained purified silica was measured. The results are shown in Table 1.
The obtained purified silica, after drying , Na: 62 ppm, S: 91 ppm, Al: less than detection limit (less than 0.5 ppm), Fe: 0.9 ppm, Ca: less than detection limit (less than 0.5 ppm), B: The component composition was less than the detection limit (less than 0.05 ppm) and P: less than the detection limit (less than 1.0 ppm). Further, the recovery rate of Si was 66%.
［実施例１７］
珪質頁岩（成分組成；ＳｉＯ２：８０質量％、Ａｌ２Ｏ３：１０質量％、Ｆｅ２Ｏ３：５質量％、Ｂ：１５０ｐｐｍ、Ｐ：３３０ｐｐｍ）を、ボールミルを用いて粉砕し、珪質頁岩粉末（最大粒径：０．５ｍｍ）を得た。
原料として使用した珪質頁岩について、Ｃｕ−Ｋα線による粉末Ｘ線の回折強度、オパールＣＴの半値幅を、粉末Ｘ線回折装置（株式会社リガク製、ＲＩＮＴ２０００）を用いて測定した。回折強度を図２に、半値幅を図３にそれぞれ示す。使用した珪質頁岩は、石英の２θ＝２６．６ｄｅｇのピーク頂部の回折強度に対するオパールＣＴの２θ＝２１．５〜２１．９ｄｅｇのピーク頂部の回折強度の比率が、０．６８であった。また、オパールＣＴの半値幅は、１．４°であった。
次いで、得られた珪質頁岩粉末２５０ｇと、２．５Ｎ水酸化ナトリウム水溶液１０００ｇを混合して、７０℃に加温した後に、６０分間混合撹拌し、ｐＨが１３．５であるスラリーを得た。
このスラリーを減圧下でブフナー漏斗で固液分離し、Ｓｉの濃度が１０．０質量％の液分７００ｇを得た。
[Example 17]
Siliceous shale (component composition; SiO 2 : 80 mass%, Al 2 O 3 : 10 mass%, Fe 2 O 3 : 5 mass%, B: 150 ppm, P: 330 ppm) is pulverized using a ball mill, A quality shale powder (maximum particle size: 0.5 mm) was obtained.
About the siliceous shale used as a raw material, the diffraction intensity of powder X-rays by Cu-Kα ray and the half width of opal CT were measured using a powder X-ray diffractometer (RINT2000, manufactured by Rigaku Corporation). The diffraction intensity is shown in FIG. 2, and the half width is shown in FIG. The siliceous shale used had a ratio of the diffraction intensity at the peak top of 2θ = 21.5 to 21.9 deg of opal CT to the diffraction intensity at the peak top of 2θ = 26.6 deg of quartz of 0.68. The half width of the opal CT was 1.4 °.
Next, 250 g of the obtained siliceous shale powder and 1000 g of 2.5N sodium hydroxide aqueous solution were mixed and heated to 70 ° C., and then mixed and stirred for 60 minutes to obtain a slurry having a pH of 13.5. .
This slurry was subjected to solid-liquid separation with a Buchner funnel under reduced pressure to obtain 700 g of a liquid having a Si concentration of 10.0% by mass.
得られた液分（ケイ酸アルカリ水溶液）に３５質量％の過酸化水素水４．４ｍｌを添加し、次いで、過酸化水素が添加されたケイ酸アルカリ水溶液６６．２ｇを硫酸濃度１０．７体積％の硫酸２００ｇ中に滴下し、析出温度を２０℃に保ちながら沈降性シリカを析出させた後、減圧下でブフナー漏斗を用いて固液分離し、ＳｉＯ２を含む固形分（沈降性シリカ）１４．６ｇと、不純物を含む液分２５１．６ｇを得た。なお、ｐＨは滴下終了まで１．０以下に保った。
得られたＳｉＯ２を含む固形分（沈降性シリカ）に対して、常温（２５℃）下で硫酸濃度１０．７体積％の硫酸を２００ｇ添加してｐＨが３．０未満のスラリーとした。このスラリーを固液分離した後に、得られた固形分を蒸留水を用いて水洗した。その後、１０５℃で１日乾燥させ、精製シリカ７．３ｇを得た。
得られた精製シリカ中のチタン（Ｔｉ）の濃度を測定した。その結果を表１に示す。
得られた精製シリカは、乾燥後に、ＳｉＯ２：９９．９９９質量％、Ｎａ：１．２ｐｐｍ、Ｓ：２．４ｐｐｍ、Ａｌ：検出限界未満（０．５ｐｐｍ未満）、Ｆｅ：０．４ｐｐｍ、Ｃａ：検出限界未満（０．５ｐｐｍ未満）、Ｂ：検出限界未満（０．０５ｐｐｍ未満）、Ｐ：検出限界未満（１．０ｐｐｍ未満）の成分組成を有していた。また、Ｓｉの回収率は４９％であった。
To the obtained liquid (alkaline silicate aqueous solution) was added 4.4 ml of 35% by mass hydrogen peroxide solution, and then 66.2 g of the alkali silicate aqueous solution to which hydrogen peroxide was added was added to 10.7 volumes of sulfuric acid. The solution was added dropwise to 200 g of 1% sulfuric acid, and precipitated silica was precipitated while maintaining the precipitation temperature at 20 ° C., and then solid-liquid separation was performed using a Buchner funnel under reduced pressure to obtain a solid content containing SiO 2 (precipitated silica). 14.6 g and 251.6 g of a liquid containing impurities were obtained. The pH was kept at 1.0 or lower until the end of dropping.
200 g of sulfuric acid having a sulfuric acid concentration of 10.7 vol% was added to the solid content (precipitating silica) containing SiO 2 at room temperature (25 ° C.) to obtain a slurry having a pH of less than 3.0. The slurry was subjected to solid-liquid separation, and the obtained solid content was washed with distilled water. Then, it was dried at 105 ° C. for 1 day to obtain 7.3 g of purified silica.
The concentration of titanium (Ti) in the obtained purified silica was measured. The results are shown in Table 1.
The obtained purified silica is, after drying, SiO 2 : 99.999 mass%, Na: 1.2 ppm, S: 2.4 ppm, Al: less than detection limit (less than 0.5 ppm), Fe: 0.4 ppm, Ca : Less than detection limit (less than 0.5 ppm), B: Less than detection limit (less than 0.05 ppm), P: Less than detection limit (less than 1.0 ppm). Moreover, the recovery rate of Si was 49%.
［比較例１］
水ガラス溶液（富士化学（株）製：ＳｉＯ２／Ｎａ２Ｏ（モル比）＝３．２０）１４０ｇに水３５ｇを加えて、Ｓｉ濃度１０．０質量％の水ガラス溶液を得た。
得られた水ガラス水溶液６６．２ｇを硫酸濃度１０．７体積％の硫酸２００ｇ中に滴下し、常温（２５℃）下で沈降性シリカを析出させた後、減圧下でブフナー漏斗を用いて固液分離し、ＳｉＯ２を含む固形分（沈降性シリカ）１９．４ｇと、不純物を含む液分２４６．８ｇを得た。なお、ｐＨは滴下終了時まで１．０以下に保った。
得られたＳｉＯ２を含む固形分（沈降性シリカ）に対して、常温（２５℃）下で硫酸濃度１０．７体積％の硫酸を２００ｇ添加してｐＨが３．０未満のスラリーとした。このスラリーを固液分離した後に、得られた固形分を、蒸留水を用いて水洗した。その後、１０５℃で１日乾燥させ、精製シリカ９．７ｇを得た。
得られた精製シリカ中のチタン（Ｔｉ）の濃度を測定した。その結果を表１に示す。
得られた精製シリカは、乾燥後に、ＳｉＯ２：９９．９９質量％、Ｎａ：１．８ｐｐｍ、Ｓ：検出限界未満（３．３ｐｐｍ未満）、Ａｌ：検出限界未満（０．５ｐｐｍ未満）、Ｆｅ：０．９ｐｐｍ、Ｃａ：検出限界未満（０．５ｐｐｍ未満）、Ｂ：検出限界未満（０．０５ｐｐｍ未満）、Ｐ：検出限界未満（１．０ｐｐｍ未満）の成分組成を有していた。また、Ｓｉの回収率は６５％であった。
[Comparative Example 1]
35 g of water was added to 140 g of a water glass solution (Fuji Chemical Co., Ltd. product: SiO 2 / Na 2 O (molar ratio) = 3.20) to obtain a water glass solution having a Si concentration of 10.0% by mass.
66.2 g of the aqueous water glass solution thus obtained was dropped into 200 g of sulfuric acid having a sulfuric acid concentration of 10.7% by volume, and precipitated silica was precipitated at room temperature (25 ° C.), and then solidified using a Buchner funnel under reduced pressure. Liquid separation was performed to obtain 19.4 g of a solid content (precipitating silica) containing SiO 2 and 246.8 g of a liquid content containing impurities. The pH was kept at 1.0 or less until the end of dropping.
200 g of sulfuric acid having a sulfuric acid concentration of 10.7 vol% was added to the solid content (precipitating silica) containing SiO 2 at room temperature (25 ° C.) to obtain a slurry having a pH of less than 3.0. After this slurry was subjected to solid-liquid separation, the obtained solid content was washed with distilled water. Thereafter, it was dried at 105 ° C. for 1 day to obtain 9.7 g of purified silica.
The concentration of titanium (Ti) in the obtained purified silica was measured. The results are shown in Table 1.
The obtained purified silica is, after drying, SiO 2 : 99.99% by mass, Na: 1.8 ppm, S: less than detection limit (less than 3.3 ppm), Al: less than detection limit (less than 0.5 ppm), Fe : 0.9 ppm, Ca: less than detection limit (less than 0.5 ppm), B: less than detection limit (less than 0.05 ppm), P: less than detection limit (less than 1.0 ppm). Moreover, the recovery rate of Si was 65%.
実施例１〜１７の結果から、本発明の製造方法により得られたシリカは、シリカの含有率が高いと共に、比較例１に比べて、不純物の一つであるチタンの含有率が少ない。また、他の不純物（Ｎａ、Ｓ、Ａｌ、Ｆｅ、Ｃａ、Ｂ、Ｐ）の含有率も少ないことがわかる。 From the results of Examples 1 to 17, the silica obtained by the production method of the present invention has a high silica content and a lower content of titanium, which is one of the impurities, than Comparative Example 1. Moreover, it turns out that the content rate of other impurities (Na, S, Al, Fe, Ca, B, P) is also small.
Claims (12)
前記工程（Ｂ）において、ケイ酸アルカリ水溶液、及び鉱酸の少なくともいずれか一方と過酸化水素を混合することを特徴とする高純度シリカの製造方法。 (B) An alkali silicate aqueous solution having a Si concentration in the liquid of 10.0% by mass or more and a mineral acid having a concentration of 10.0% by volume or more are mixed so that the Si in the liquid is non-gelled. After precipitation as silica, solid-liquid separation is performed, and includes a silica recovery step of obtaining a solid content containing SiO 2 and a liquid content containing impurities,
In the step (B), hydrogen peroxide is mixed with at least one of an alkali silicate aqueous solution and a mineral acid, and a method for producing high purity silica.
（Ｃ）工程（Ｂ）で得られたＳｉＯ２を含む固形分と鉱酸を混合して、ｐＨが３．０未満の酸性スラリーを調製し、上記固形分中に残存する不純物を溶解させた後、上記酸性スラリーを固液分離して、ＳｉＯ２を含む固形分と、不純物を含む液分を得る酸洗浄工程、を含み、
前記工程（Ｃ）において、鉱酸と過酸化水素を混合することを特徴とする高純度シリカの製造方法。 (B) An alkali silicate aqueous solution having a Si concentration in the liquid of 10.0% by mass or more and a mineral acid having a concentration of 10.0% by volume or more are mixed so that the Si in the liquid is non-gelled. After precipitation as silica, solid-liquid separation is performed, and a silica recovery step for obtaining a solid content containing SiO 2 and a liquid content containing impurities,
(C) The solid content containing SiO 2 obtained in the step (B) and the mineral acid were mixed to prepare an acidic slurry having a pH of less than 3.0, and the impurities remaining in the solid content were dissolved. Thereafter, the acidic slurry is subjected to solid-liquid separation to obtain a solid content containing SiO 2 and an acid cleaning step of obtaining a liquid content containing impurities.
In the step (C), a mineral acid and hydrogen peroxide are mixed.
を含む請求項１〜１１のいずれか１項に記載の高純度シリカの製造方法。 (D) The solid content containing SiO 2 obtained in the previous step and water are mixed to dissolve impurities remaining in the solid content, and then the slurry is solid-liquid separated to obtain a solid containing SiO 2 And a water washing step for obtaining a liquid containing impurities.
The manufacturing method of the high purity silica of any one of Claims 1-11 containing these.
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