JP6870232B2 - Manufacturing method of nickel oxide fine powder - Google Patents
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本発明は、酸化ニッケル微粉末の製造方法に関し、特に、硫黄品位が制御されており且つ塩素やナトリウム等の不純物品位が低く、電子部品や固体酸化物形燃料電池の電極に用いられる材料として好適な微細な酸化ニッケル微粉末の製造方法に関する。 The present invention relates to a method for producing fine nickel oxide powder, and is particularly suitable as a material used for an electronic component or an electrode of a solid oxide fuel cell because the sulfur grade is controlled and the impurity grade such as chlorine and sodium is low. The present invention relates to a method for producing fine nickel oxide fine powder.
一般に、酸化ニッケル微粉末は、硫酸ニッケル、硝酸ニッケル、炭酸ニッケル、水酸化ニッケル等のニッケル塩類又はニッケルメタル粉を、酸化性雰囲気下で焼成することによって製造される。これらの酸化ニッケル微粉末は、電子部品用材料や固体酸化物形燃料電池の電極用材料等の多様な用途に用いられている。例えば、電子部品材料としての用途では、酸化ニッケル微粉末を酸化鉄や酸化亜鉛等の他の材料と混合した後、焼結することにより作製されるフェライト部品等が広く用いられている。 Generally, nickel oxide fine powder is produced by firing nickel salts such as nickel sulfate, nickel nitrate, nickel carbonate, nickel hydroxide, or nickel metal powder in an oxidizing atmosphere. These nickel oxide fine powders are used in various applications such as materials for electronic parts and materials for electrodes of solid oxide fuel cells. For example, in applications as electronic component materials, ferrite components produced by mixing fine nickel oxide powder with other materials such as iron oxide and zinc oxide and then sintering them are widely used.
上記フェライト部品のように、複数の材料を混合して焼成することにより、これらを反応させて複合金属酸化物を製造する場合には、生成反応は固相の拡散反応で律速されるので、使用する原料としては一般に微細なものが好適に用いられている。これにより、他材料との接触確率が高くなると共に粒子の活性が高くなるため、低温度且つ短時間の処理で反応を均一に進ませることができる。従って、このような複合金属酸化物を製造する方法においては、原料となる粉体の粒径を小さくすることが効率向上の重要な要素となる。 When a plurality of materials are mixed and fired to produce a composite metal oxide as in the case of the above-mentioned ferrite parts, the production reaction is rate-determined by the diffusion reaction of the solid phase, so that it is used. Generally, fine raw materials are preferably used. As a result, the probability of contact with other materials increases and the activity of the particles increases, so that the reaction can proceed uniformly at a low temperature and in a short time. Therefore, in the method for producing such a composite metal oxide, reducing the particle size of the powder as a raw material is an important factor for improving efficiency.
また、環境及びエネルギーの両面から新しい発電システムとして期待されている固体酸化物形燃料電池では、その電極材料として酸化ニッケル微粉末が用いられている。一般に、固体酸化物形燃料電池のセルスタックは、空気極、固体電解質及び燃料極からなる単セルが複数セル積層された構造を有している。この燃料極としては、例えばニッケル又は酸化ニッケルと、安定化ジルコニアからなる固体電解質とを混合したものが通常用いられている。燃料極は、発電時に水素や炭化水素等の燃料ガスにより還元されてニッケルメタルとなり、ニッケルと固体電解質と空隙からなる三相界面が燃料ガスと酸素の反応場となるため、フェライト部品として用いる場合と同様に原料となる粉体の粒径を小さくして微細にすることが発電効率向上の重要な要素となる。 Further, in a solid oxide fuel cell which is expected as a new power generation system from both aspects of environment and energy, nickel oxide fine powder is used as an electrode material thereof. Generally, a cell stack of a solid oxide fuel cell has a structure in which a plurality of single cells including an air electrode, a solid electrolyte, and a fuel electrode are stacked. As the fuel electrode, for example, a mixture of nickel or nickel oxide and a solid electrolyte made of stabilized zirconia is usually used. The fuel electrode is reduced to nickel metal by fuel gas such as hydrogen or hydrocarbon during power generation, and the three-phase interface consisting of nickel, solid electrolyte, and voids serves as a reaction field for fuel gas and oxygen. Similarly, reducing the particle size of the raw material powder to make it finer is an important factor for improving power generation efficiency.
ところで、粉体が微細であることを測る指標としては、比表面積を用いることがある。また、粒径と比表面積には、下記の計算式１の関係があることが知られている。下記計算式１の関係は粒子が真球状であると仮定して導き出されたものであるため、計算式１から得られる粒径と実際の粒径との間にはいくらかの誤差を含むことになるが、比表面積が大きいほど粒径が小さくなることが分る。 By the way, the specific surface area may be used as an index for measuring the fineness of the powder. Further, it is known that the particle size and the specific surface area have a relationship of the following formula 1. Since the relationship of the following formula 1 is derived on the assumption that the particles are spherical, some error is included between the particle size obtained from the formula 1 and the actual particle size. However, it can be seen that the larger the specific surface area, the smaller the particle size.
［計算式１］
粒径＝６／（密度×比表面積）
[Calculation formula 1]
Particle size = 6 / (density x specific surface area)
近年、フェライト部品はますます高機能化する傾向にあり、また酸化ニッケル微粉末の用途はフェライト部品以外の電子部品等に広がっている。これに伴い、酸化ニッケル微粉末に含有される不純物元素の品位を低減することが求められている。不純物元素の中でも特に塩素や硫黄は、電極に利用されている銀と反応して電極劣化を生じさせたり、焼成炉を腐食させたりすることがあるため、できるだけ低減することが望ましい。 In recent years, ferrite parts have become more and more sophisticated, and the use of nickel oxide fine powder has expanded to electronic parts other than ferrite parts. Along with this, it is required to reduce the grade of impurity elements contained in the nickel oxide fine powder. Among the impurity elements, chlorine and sulfur may react with silver used for the electrode to cause electrode deterioration and corrode the firing furnace, so it is desirable to reduce them as much as possible.
例えば特許文献１には、原料段階におけるフェライト粉の硫黄成分の含有量がＳ換算で３００〜９００ｐｐｍ且つ塩素成分の含有量がＣｌ換算で１００ｐｐｍであり、焼成後のフェライト焼結体の硫黄成分の含有量がＳ換算で１００ｐｐｍ以下且つ塩素成分の含有量がＣｌ換算で２５ｐｐｍ以下のフェライト材料が開示されている。このフェライト材料は、低温焼成においても添加物を用いることなく高密度化を図ることができ、これにより作製されたフェライト磁心及び積層チップ部品は、耐湿性と温度特性に優れていると記載されている。 For example, in Patent Document 1, the content of the sulfur component of the ferrite powder at the raw material stage is 300 to 900 ppm in terms of S and the content of the chlorine component is 100 ppm in terms of Cl. A ferrite material having a content of 100 ppm or less in terms of S and a content of chlorine component of 25 ppm or less in terms of Cl is disclosed. It is stated that this ferrite material can be densified without using additives even in low-temperature firing, and that the ferrite core and laminated chip parts produced by this are excellent in moisture resistance and temperature characteristics. There is.
また、原料に硫酸ニッケルを用い、これを焙焼することで酸化ニッケル微粉末を製造する方法も提案されている。例えば、特許文献２には、原料としての硫酸ニッケルを、キルンなどを用いて酸化雰囲気中で９５０〜１０００℃で焙焼する第１段焙焼と、１０００〜１２００℃で焙焼する第２段焙焼とを行って酸化ニッケル粉末を製造する方法が提案されている。この製造方法によれば、平均粒径が制御され、且つ硫黄品位が５０質量ｐｐｍ以下である酸化ニッケル微粉末が得られると記載されている。 In addition, a method of producing nickel oxide fine powder by using nickel sulfate as a raw material and roasting it has also been proposed. For example, Patent Document 2 describes a first-stage roasting in which nickel sulfate as a raw material is roasted at 950 to 1000 ° C. in an oxidizing atmosphere using a kiln or the like, and a second-stage roasting in which the nickel sulfate is roasted at 1000 to 1200 ° C. A method of producing nickel oxide powder by roasting has been proposed. According to this production method, it is described that nickel oxide fine powder having an average particle size controlled and a sulfur grade of 50 mass ppm or less can be obtained.
また、特許文献３には、４５０〜６００℃の仮焼による原料の硫酸ニッケルの脱水工程と、１０００〜１２００℃の焙焼による硫酸ニッケルの分解工程とを明確に分離した酸化ニッケル粉末の製造方法が提案されている。この製造方法によれば、硫黄品位が低く且つ平均粒径が小さい酸化ニッケル粉末を安定して製造できると記載されている。 Further, Patent Document 3 describes a method for producing nickel oxide powder in which a step of dehydrating nickel sulfate as a raw material by calcining at 450 to 600 ° C. and a step of decomposing nickel sulfate by roasting at 1000 to 1200 ° C. are clearly separated. Has been proposed. According to this production method, it is described that nickel oxide powder having a low sulfur grade and a small average particle size can be stably produced.
更に、特許文献４には、横型回転式製造炉を用いて、強制的に空気を導入しながら、最高温度を９００〜１２５０℃として硫酸ニッケルを焙焼する方法が提案されている。この製造方法によっても、不純物が少なく、硫黄品位が５００質量ｐｐｍ以下の酸化ニッケル粉末が得られると記載されている。 Further, Patent Document 4 proposes a method of roasting nickel sulfate at a maximum temperature of 900 to 1250 ° C. while forcibly introducing air using a horizontal rotary manufacturing furnace. It is described that nickel oxide powder having a small amount of impurities and a sulfur grade of 500 mass ppm or less can be obtained by this production method as well.
上記の特許文献２や特許文献３の方法によれば不純物品位の低い酸化ニッケル微粉末が得られるが、熱処理を２回行うため生産コストが高くなってしまう。また、上記特許文献２〜４のいずれの方法においても、硫黄品位を低減するために焙焼温度を高くすると粒径が粗大になり、逆に粒子を微細にするために焙焼温度を下げると硫黄品位が高くなるため、粒径と硫黄品位を共に最適値に制御することは困難である。更に、加熱する際にＳＯｘを含むガスが大量に発生し、これを除害処理するために高価な設備が必要になるという問題を抱えている。 According to the methods of Patent Document 2 and Patent Document 3 described above, nickel oxide fine powder having a low impurity grade can be obtained, but the production cost is high because the heat treatment is performed twice. Further, in any of the methods of Patent Documents 2 to 4, when the roasting temperature is raised in order to reduce the sulfur grade, the particle size becomes coarse, and conversely, when the roasting temperature is lowered in order to make the particles finer. Since the sulfur grade is high, it is difficult to control both the particle size and the sulfur grade to the optimum values. Further, there is a problem that a large amount of gas containing SOx is generated during heating, and expensive equipment is required for detoxifying the gas.
酸化ニッケル微粉末を合成する方法として、硫酸ニッケルや塩化ニッケル等のニッケル塩を含む水溶液を、水酸化ナトリウム水溶液等のアルカリで中和して水酸化ニッケル粒子を晶析させ、これを焙焼する方法も提案されている。このように、水酸化ニッケル粒子を焙焼する場合は、陰イオン成分由来のガスの発生が少ないため、排ガス処理が不要となるか若しくは簡易な設備でよく、生産コストを抑えることが可能になると考えられる。 As a method for synthesizing nickel oxide fine powder, an aqueous solution containing a nickel salt such as nickel sulfate or nickel chloride is neutralized with an alkali such as an aqueous solution of sodium hydroxide to crystallize nickel hydroxide particles, which are then roasted. A method has also been proposed. In this way, when roasting nickel hydroxide particles, the generation of gas derived from anionic components is small, so exhaust gas treatment is not required or simple equipment is sufficient, and production costs can be suppressed. Conceivable.
例えば、特許文献５には、塩化ニッケル水溶液をアルカリで中和し、得られた水酸化ニッケル粒子を５００〜８００℃の温度で熱処理して酸化ニッケル粉末を生成し、得られた酸化ニッケル粉末に水を加えてスラリー化した後、湿式ジェットミルを用いて解砕すると同時に洗浄することにより、硫黄品位及び塩素品位が低く、且つ微細な酸化ニッケル微粉末を得る方法が提案されている。 For example, in Patent Document 5, the nickel chloride aqueous solution is neutralized with alkali, and the obtained nickel hydroxide particles are heat-treated at a temperature of 500 to 800 ° C. to produce nickel oxide powder, and the obtained nickel oxide powder is obtained. A method has been proposed in which water is added to form a slurry, which is then crushed using a wet jet mill and simultaneously washed to obtain fine nickel oxide fine powder having low sulfur and chlorine grades.
上記の特許文献５の酸化ニッケル微粉末の製造方法は、原料に塩化ニッケルを用いているので硫黄の低減は可能であるが、硫黄品位を所定の範囲内に制御することは困難であった。また、湿式解砕を要件としているため、この湿式解砕後の乾燥時に粒子同士が凝集するおそれがある上、乾燥に要するエネルギーがコスト的に不利になることがあった。 In the method for producing nickel oxide fine powder of Patent Document 5 above, since nickel chloride is used as a raw material, sulfur can be reduced, but it is difficult to control the sulfur grade within a predetermined range. Further, since wet crushing is a requirement, particles may agglomerate during drying after the wet crushing, and the energy required for drying may be disadvantageous in terms of cost.
本発明は、上記した従来の問題点に鑑みてなされたものであり、含有量が制御された微量の硫黄を含み、不純物品位、特に塩素品位が低く、電子部品材料や固体酸化物形燃料電池の電極材料として好適な微細な酸化ニッケル微粉末の製造方法を提供することを目的とする。 The present invention has been made in view of the above-mentioned conventional problems, contains a trace amount of sulfur whose content is controlled, has a low impurity grade, particularly chlorine grade, and is used as an electronic component material or a solid oxide fuel cell. It is an object of the present invention to provide a method for producing a fine nickel oxide fine powder suitable as an electrode material of the above.
上記目的を達成するため、本発明者らは熱処理時に除害を要するガスが大量に発生するのを避けるため、ニッケル塩水溶液を中和することで生成される水酸化ニッケルを焙焼して酸化ニッケル微粉末を製造する方法に着目して鋭意研究を重ねた結果、硫酸ニッケル水溶液をアルカリで中和することで生成される水酸化ニッケルを所定の条件で熱処理することで、硫黄品位が制御され、不純物品位、特に塩素品位が低い微細な酸化ニッケル微粉末を生成できることを見出し、本発明を完成するに至った。 In order to achieve the above object, the present inventors roast and oxidize nickel hydroxide produced by neutralizing an aqueous nickel salt solution in order to avoid generating a large amount of gas requiring detoxification during heat treatment. As a result of intensive research focusing on the method of producing nickel fine powder, the sulfur grade is controlled by heat-treating nickel hydroxide produced by neutralizing the nickel sulfate aqueous solution with alkali under predetermined conditions. , It has been found that fine nickel oxide fine powder having a low impurity grade, particularly a chlorine grade, can be produced, and the present invention has been completed.
すなわち、本発明の酸化ニッケル微粉末の製造方法は、硫酸ニッケル水溶液をアルカリで中和することで硫黄を含有し且つレーザー散乱法で測定したＤ９０が５〜６０μｍの水酸化ニッケル粒子を生成した後、該水酸化ニッケル粒子の硫黄品位を１.０〜３.０質量％（１.０質量％を除く）となるように水による洗浄を行う中和工程と、前記中和工程で得た水酸化ニッケル粒子を非還元性雰囲気中において８５０℃を超え１０５０℃未満の温度で熱処理して酸化ニッケル粉末を生成する熱処理工程とを含む酸化ニッケル微粉末の製造方法であって、前記熱処理工程において前記水酸化ニッケル粒子を流動させながら該水酸化ニッケル粒子１ｇに対して５〜１５０ＮＬの範囲内において非還元性ガスの通気量を調整することによって該酸化ニッケル粉末の硫黄品位を５０質量ｐｐｍ以下に制御することを特徴としている。 That is, the manufacturing method of the nickel oxide fine powder of the present invention, after D90 measured by and laser scattering method contains sulfur by neutralizing the aqueous nickel sulfate solution with alkali to produce nickel hydroxide particles 5~60μm , A neutralization step of washing with water so that the sulfur grade of the nickel hydroxide particles is 1.0 to 3.0% by mass (excluding 1.0% by mass), and water obtained in the neutralization step. A method for producing fine nickel oxide powder, which comprises a heat treatment step of heat-treating nickel oxide particles in a non-reducing atmosphere at a temperature of more than 850 ° C. and lower than 1050 ° C. to produce nickel oxide powder. control of sulfur grade nickel oxide powder in 50 mass ppm or less by adjusting the aeration of the non-reducing gas in the range of 5 ～150NL with respect aqueous nickel oxide particles 1g in flowing nickel hydroxide particles It is characterized in that.
本発明によれば、フェライト部品などの電子部品材料や固体酸化物形燃料電池の電極材料として好適な不純物品位が低くて微細な酸化ニッケル微粉末を塩素やＳＯｘガスを大量に発生させることなく容易に作製することができる。 According to the present invention, it is easy to produce fine nickel oxide fine powder having a low impurity grade, which is suitable as an electronic component material such as a ferrite component or an electrode material for a solid oxide fuel cell, without generating a large amount of chlorine or SOx gas. Can be made into.
以下、本発明の酸化ニッケル微粉末の製造方法の一具体例について説明する。この本発明の一具体例の酸化ニッケル微粉末の製造方法は、原料としての硫酸ニッケル水溶液をアルカリで中和することで硫黄を含有する水酸化ニッケル粒子を生成する中和工程と、該中和工程で得た水酸化ニッケル粒子を非還元性雰囲気中において非還元性ガスを通気しながら８５０℃を超え１０５０℃未満の温度で熱処理して酸化ニッケル粉末を生成する熱処理工程と、該熱処理により得た酸化ニッケル粉末に対して必要に応じて解砕処理を施す解砕工程とを有している。 Hereinafter, a specific example of the method for producing the nickel oxide fine powder of the present invention will be described. The method for producing fine nickel oxide powder as a specific example of the present invention includes a neutralization step of producing nickel hydroxide particles containing sulfur by neutralizing an aqueous solution of nickel sulfate as a raw material with alkali, and the neutralization. The nickel hydroxide particles obtained in the step are heat-treated at a temperature of more than 850 ° C. and lower than 1050 ° C. while aerating a non-reducing gas in a non-reducing atmosphere to produce nickel oxide powder, and the heat treatment is carried out. It has a crushing step in which the nickel oxide powder is crushed as needed.
このように、本発明の一具体例の製造方法においては、原料のニッケル塩水溶液に硫酸ニッケルを使用することが重要である。すなわち、硫酸ニッケルを使用することによって、従来のニッケル塩を用いた場合と比べ、後段の熱処理工程の温度を高温に設定しても微細な酸化ニッケル微粉末を得ることが可能になる。よって、電子部品材料としての用途、特にフェライト部品の原料として用いる場合に好適な微細でかつ硫黄品位が制御された酸化ニッケル微粉末を得ることができる。 As described above, in the production method of one specific example of the present invention, it is important to use nickel sulfate as the raw material nickel salt aqueous solution. That is, by using nickel sulfate, it becomes possible to obtain fine nickel oxide fine powder even if the temperature of the heat treatment step in the subsequent stage is set to a high temperature, as compared with the case where a conventional nickel salt is used. Therefore, it is possible to obtain fine nickel oxide fine powder having a controlled sulfur grade, which is suitable for use as a material for electronic parts, particularly as a raw material for ferrite parts.
本発明者らは、硫黄の含有量を単に低減するのではなく、硫黄の含有量を所定の範囲内に厳密に制御することで当該硫黄成分の働きにより酸化ニッケル微粉末の粒径に及ぼす熱処理温度の影響を抑え得るとの知見を得、これに基づき熱処理温度を特定の範囲で制御したところ微細な粒径を維持したまま酸化ニッケル微粉末の硫黄品位を制御できることを見出した。しかも、この方法は塩化ニッケルを用いないため塩素が混入するおそれがなく、よって、原料に不可避的に含まれる不純物由来のもの以外は実質的に塩素を含有しない酸化ニッケル微粉末を得ることができる。 The present inventors do not simply reduce the sulfur content, but heat-treat the particle size of the nickel oxide fine powder by the action of the sulfur component by strictly controlling the sulfur content within a predetermined range. Based on the finding that the influence of temperature can be suppressed, it was found that when the heat treatment temperature was controlled in a specific range, the sulfur grade of the nickel oxide fine powder could be controlled while maintaining the fine particle size. Moreover, since this method does not use nickel chloride, there is no risk of chlorine being mixed in, so that nickel oxide fine powder that does not substantially contain chlorine except for those derived from impurities inevitably contained in the raw material can be obtained. ..
上記方法で微細な粒径の酸化ニッケル微粉末が得られる明確な理由は不明であるが、硫酸ニッケルの分解温度は８４８℃と高温であるため、中和により晶析した水酸化ニッケル粒子の表面や界面に硫酸塩として巻きこまれた硫黄成分が酸化ニッケル粉末の焼結を高温まで抑制していると考えられる。この場合、硫酸ニッケルの分解温度より高温で熱処理すれば硫黄成分は揮発されるため、熱処理後の酸化ニッケル微粉末の硫黄品位を低減することができる。 The clear reason why fine nickel oxide powder having a fine particle size can be obtained by the above method is unknown, but since the decomposition temperature of nickel sulfate is as high as 848 ° C., the surface of nickel hydroxide particles crystallized by neutralization. It is considered that the sulfur component caught as a sulfate at the interface suppresses the sintering of nickel oxide powder to a high temperature. In this case, if the heat treatment is performed at a temperature higher than the decomposition temperature of nickel sulfate, the sulfur component is volatilized, so that the sulfur grade of the nickel oxide fine powder after the heat treatment can be reduced.
即ち、水酸化ニッケル粒子内の水酸基の脱離により酸化ニッケル微粉末の生成が行われる上記熱処理工程では、熱処理温度を適切に設定することによって、粒径の微細化と硫黄品位の制御が可能である。具体的には、水酸化ニッケルの熱処理温度を、８５０℃を超え１０５０℃未満の温度範囲、好ましくは８６０以上１０００℃以下の温度範囲とすることで、酸化ニッケル微粉末の硫黄品位を５０質量ｐｐｍ以下に制御すると共に、比表面積を３ｍ２／ｇ以上４ｍ２／ｇ未満にすることができる。以下、かかる本発明の一具体例の酸化ニッケルの製造方法を工程毎に詳細に説明する。 That is, in the above heat treatment step in which the nickel oxide fine powder is generated by the desorption of the hydroxyl group in the nickel hydroxide particles, the particle size can be made finer and the sulfur grade can be controlled by appropriately setting the heat treatment temperature. is there. Specifically, by setting the heat treatment temperature of nickel hydroxide in the temperature range of more than 850 ° C. and lower than 1050 ° C., preferably in the temperature range of 860 or more and 1000 ° C. or less, the sulfur grade of the nickel oxide fine powder is 50% by mass ppm. While controlling as follows, the specific surface area can be 3 m 2 / g or more and less than 4 m 2 / g. Hereinafter, a method for producing nickel oxide, which is a specific example of the present invention, will be described in detail for each step.
［中和工程］
先ず中和工程において、原料としての硫酸ニッケル水溶液をアルカリ成分で中和することで水酸化ニッケル粒子の析出を行う。原料として用いる硫酸ニッケルは、特に限定するものではないが、最終的に作製される酸化ニッケル微粉末が電子部品材料用や固体酸化物形燃料電池の電極用として用いられることから、腐食を防止するため、原料中に含まれる不純物が１００質量ｐｐｍ未満であることが望ましい。
[Neutralization process]
First, in the neutralization step, nickel hydroxide particles are precipitated by neutralizing an aqueous solution of nickel sulfate as a raw material with an alkaline component. The nickel sulfate used as a raw material is not particularly limited, but since the nickel oxide fine powder finally produced is used for an electronic component material or an electrode of a solid oxide fuel cell, corrosion is prevented. Therefore, it is desirable that the impurities contained in the raw material are less than 100 mass ppm.
また、硫酸ニッケル水溶液中のニッケルの濃度は、特に限定するものではないが、生産性を考慮するとニッケル濃度で５０〜１５０ｇ／Ｌが好ましい。この濃度が５０ｇ／Ｌ未満では生産性が低下するおそれがある。逆に１５０ｇ／Ｌを超えると水溶液中の陰イオン濃度が高くなりすぎ、生成した水酸化ニッケル中の硫黄品位が高くなるため、最終的に得られる酸化ニッケル微粉末中の不純物品位が十分に低くならない場合がある。 The concentration of nickel in the nickel sulfate aqueous solution is not particularly limited, but the nickel concentration is preferably 50 to 150 g / L in consideration of productivity. If this concentration is less than 50 g / L, productivity may decrease. On the contrary, if it exceeds 150 g / L, the anion concentration in the aqueous solution becomes too high and the sulfur grade in the produced nickel hydroxide becomes high, so that the impurity grade in the finally obtained nickel oxide fine powder is sufficiently low. It may not be.
中和に用いるアルカリ成分としては、特に限定するものではないが、反応液中に残留するニッケルの量を考慮するとアルカリ金属の水酸化物が好ましい。特に、水酸化ナトリウムや水酸化カリウムがより好ましく、コストを考慮すると水酸化ナトリウムが最も好ましい。上記アルカリ成分は固体又は液体のいずれの形態で硫酸ニッケル水溶液に添加してもよいが、取扱いの容易さから水溶液の形態で添加することが好ましい。 The alkali component used for neutralization is not particularly limited, but an alkali metal hydroxide is preferable in consideration of the amount of nickel remaining in the reaction solution. In particular, sodium hydroxide and potassium hydroxide are more preferable, and sodium hydroxide is most preferable in consideration of cost. The alkaline component may be added to the nickel sulfate aqueous solution in either solid or liquid form, but it is preferably added in the form of an aqueous solution for ease of handling.
均一な特性の水酸化ニッケル粒子を効率よく生産するためには、反応槽内において十分に撹拌されている液に、予め調製しておいたニッケル塩水溶液である硫酸ニッケル水溶液とアルカリ水溶液とをいわゆるダブルジェット方式で添加する連続晶析法が有効である。即ち、反応槽内に予め準備したニッケル塩水溶液又はアルカリ水溶液のうちのいずれか一方に対して、もう一方を添加することで中和するのではなく、反応槽内において十分に攪拌されている乱流状態の液中に、好適には該攪拌を継続しながらニッケル塩水溶液とアルカリ水溶液とを同時並行的に且つ連続的に添加することで混合して反応液とする方式が有効である。その際、反応槽内に予め入れておく液は、純水に上記アルカリ成分を添加して所定のｐＨに調整したものが好ましい。 In order to efficiently produce nickel hydroxide particles having uniform characteristics, a nickel sulfate aqueous solution and an alkaline aqueous solution, which are nickel salt aqueous solutions prepared in advance, are added to a liquid that is sufficiently stirred in the reaction vessel. The continuous crystallization method in which the particles are added by the double jet method is effective. That is, it is not neutralized by adding the other to either one of the nickel salt aqueous solution or the alkaline aqueous solution prepared in advance in the reaction vessel, but the disturbance is sufficiently stirred in the reaction vessel. It is preferable to add a nickel salt aqueous solution and an alkaline aqueous solution to the liquid in a flowing state in parallel and continuously while continuing the stirring to mix them to obtain a reaction liquid. At that time, the liquid to be put in the reaction vessel in advance is preferably one in which the above-mentioned alkaline component is added to pure water to adjust the pH to a predetermined value.
上記の中和反応時は、反応液のｐＨを８.３〜９.０の範囲内に設定することが好ましく、特にこの範囲内でｐＨをほぼ一定に保つことが好ましい。このｐＨが８.３より低いと、水酸化ニッケル粒子中に残存する硫酸イオン等の陰イオン成分の濃度が増大し、これらが後段の熱処理工程の際に大量のＳＯｘ等となって炉体を傷めるおそれがある。逆にこのｐＨが９.０より高くなると、析出する水酸化ニッケル粒子が微細になりすぎ、この水酸化ニッケル粒子を含むスラリーを例えば濾過装置で固液分離する際に濾過性が低下することがある。更に、後段の熱処理工程で焼結が進みすぎて、微細な酸化ニッケル微粉末を得ることが困難になることがある。 During the above neutralization reaction, the pH of the reaction solution is preferably set within the range of 8.3 to 9.0, and particularly preferably the pH is kept substantially constant within this range. When this pH is lower than 8.3, the concentration of anionic components such as sulfate ions remaining in the nickel hydroxide particles increases, and these become a large amount of SOx or the like during the subsequent heat treatment step to form the furnace body. There is a risk of damage. On the contrary, when the pH is higher than 9.0, the precipitated nickel hydroxide particles become too fine, and the filterability may be lowered when the slurry containing the nickel hydroxide particles is solid-liquid separated by, for example, a filtration device. is there. Further, in the heat treatment step in the subsequent stage, sintering proceeds too much, and it may be difficult to obtain fine nickel oxide fine powder.
上記した好適な中和条件であるｐＨ９.０以下では反応後の水溶液中に僅かにニッケル成分が残存することがあるが、この場合は、上記の中和工程による晶析がほぼ完了した後にｐＨを１０程度まで上げることによって、上記の濾過により得られる濾液中のニッケル成分を低減させることができる。中和反応時のｐＨは、その変動幅が設定値を中心として絶対値で０.２以内となるように一定に制御することが好ましい。ｐＨの変動幅がこれより大きくなると、不純物が増大したり酸化ニッケル微粉末の比表面積が低下したりするおそれがある。 At pH 9.0 or lower, which is the above-mentioned suitable neutralization condition, a small amount of nickel component may remain in the aqueous solution after the reaction. In this case, the pH is almost completed after the crystallization by the above-mentioned neutralization step is almost completed. The nickel component in the filtrate obtained by the above filtration can be reduced by increasing the pH to about 10. The pH at the time of the neutralization reaction is preferably controlled to be constant so that the fluctuation range is within 0.2 in absolute value around the set value. If the pH fluctuation range is larger than this, impurities may increase or the specific surface area of the nickel oxide fine powder may decrease.
上記の中和反応時の反応液の温度には特に制約がなく、室温で行うことも可能であるが、水酸化ニッケル粒子を十分に成長させるためには５０〜７０℃の範囲内が好ましい。水酸化ニッケル粒子を十分に成長させることで、水酸化ニッケル粒子中への硫黄の過度の含有を防止することができる。また、水酸化ニッケル粒子中へのナトリウムなどの不純物の巻き込みを抑制し、最終的に得られる酸化ニッケル微粉末の不純物を低減することができる。 The temperature of the reaction solution during the above neutralization reaction is not particularly limited and can be carried out at room temperature, but it is preferably in the range of 50 to 70 ° C. in order to sufficiently grow the nickel hydroxide particles. By sufficiently growing the nickel hydroxide particles, it is possible to prevent excessive inclusion of sulfur in the nickel hydroxide particles. In addition, it is possible to suppress the entrainment of impurities such as sodium in the nickel hydroxide particles and reduce the impurities of the nickel oxide fine powder finally obtained.
この液温が５０℃未満では水酸化ニッケル粒子の成長が不十分になって、水酸化ニッケル中への硫黄等の不純物の巻き込みが多くなるおそれがある。逆に液温が７０℃を超えると水の蒸発量が増加し、水溶液中の硫黄等の不純物濃度が高くなるため、生成した水酸化ニッケル粒子中の硫黄等の不純物品位が高くなるおそれがある。上記中和反応により晶析した水酸化ニッケル粒子は、レーザー散乱法で測定したＤ９０（粒度分布曲線における粒子量の体積積算９０％での粒径）が５〜６０μｍになる。粒径がこの範囲内であれば、後段の熱処理工程において、水酸化ニッケル粒子の流動性が良好となる。 If the liquid temperature is less than 50 ° C., the growth of nickel hydroxide particles will be insufficient, and impurities such as sulfur may be more involved in nickel hydroxide. On the contrary, when the liquid temperature exceeds 70 ° C., the amount of evaporation of water increases and the concentration of impurities such as sulfur in the aqueous solution increases, so that the grade of impurities such as sulfur in the generated nickel hydroxide particles may increase. .. The nickel hydroxide particles crystallized by the neutralization reaction have a D90 (particle size at 90% volume integration of the particle size in the particle size distribution curve) measured by the laser scattering method of 5 to 60 μm. When the particle size is within this range, the fluidity of the nickel hydroxide particles becomes good in the subsequent heat treatment step.
上記中和反応の終了後は、析出した水酸化ニッケル粒子を含むスラリーを濾過等の固液分離手段により固液分離して該水酸化ニッケル粒子を固形分の形態で回収する。例えば濾過装置により回収される湿潤状態の濾過ケーキは、次の熱処理工程で処理する前に洗浄することが好ましい。洗浄はレパルプ洗浄とすることが好ましく、その場合に用いる洗浄液としては水が好ましく、純水がより好ましい。 After the completion of the neutralization reaction, the slurry containing the precipitated nickel hydroxide particles is solid-liquid separated by a solid-liquid separation means such as filtration, and the nickel hydroxide particles are recovered in the form of solid content. For example, the wet filter cake recovered by the filtration device is preferably washed before being treated in the next heat treatment step. The cleaning is preferably repulp cleaning, and water is preferable as the cleaning liquid used in that case, and pure water is more preferable.
洗浄時の水酸化ニッケルと水との混合割合は特に限定がないが、水酸化ニッケルに含まれるナトリウム等のアルカリ金属成分が十分に除去できる混合割合が好ましい。具体的には、残留するアルカリ金属等の不純物が十分に低減でき且つ水酸化ニッケル粒子を良好に分散させるため、５０〜１５０ｇの水酸化ニッケルに対して１Ｌの洗浄液を混合することが好ましく、１００ｇ程度の水酸化ニッケルに対して１Ｌの洗浄液を混合するのがより好ましい。 The mixing ratio of nickel hydroxide and water at the time of washing is not particularly limited, but a mixing ratio that can sufficiently remove alkali metal components such as sodium contained in nickel hydroxide is preferable. Specifically, in order to sufficiently reduce residual impurities such as alkali metals and to disperse nickel hydroxide particles satisfactorily, it is preferable to mix 1 L of the cleaning liquid with 50 to 150 g of nickel hydroxide, preferably 100 g. It is more preferable to mix 1 L of the cleaning solution with respect to the degree of nickel hydroxide.
尚、洗浄時間については、上記の洗浄液の量や温度などの洗浄条件に応じて適宜定めることができ、残留不純物が十分に低減可能な時間とすればよい。また、１回の洗浄でアルカリ金属等の不純物が十分に低減されない場合は、複数回繰り返して洗浄することが好ましい。特に、ナトリウム等のアルカリ金属は次工程の熱処理によっても除去できないため、この洗浄によって十分に除去することが好ましい。例えば洗浄液に純水を用いる場合は、洗浄後の洗浄液の導電率を測定して所定の導電率以下となるまで洗浄を繰り返すことで、不純物を十分に除去することができる。これにより、所望の硫黄品位を有する水酸化ニッケル粒子を得ることができる。尚、水酸化ニッケル粒子の硫黄品位は０.５〜３.０質量％が好ましく、１.０〜２.０質量％がより好ましい。 The cleaning time can be appropriately determined according to the cleaning conditions such as the amount and temperature of the cleaning liquid, and may be a time during which residual impurities can be sufficiently reduced. Further, when impurities such as alkali metal are not sufficiently reduced by one cleaning, it is preferable to repeat the cleaning a plurality of times. In particular, since alkali metals such as sodium cannot be removed by the heat treatment in the next step, it is preferable to sufficiently remove them by this cleaning. For example, when pure water is used as the cleaning liquid, impurities can be sufficiently removed by measuring the conductivity of the cleaning liquid after cleaning and repeating the cleaning until the conductivity becomes equal to or less than a predetermined conductivity. Thereby, nickel hydroxide particles having a desired sulfur grade can be obtained. The sulfur grade of the nickel hydroxide particles is preferably 0.5 to 3.0% by mass, more preferably 1.0 to 2.0% by mass.
［熱処理工程］
上記中和工程で生成した硫黄を含有する水酸化ニッケル粒子は、次に熱処理工程において熱処理を施して酸化ニッケル粉末を生成させる。この熱処理は、非還元性雰囲気中において、水酸化ニッケル粒子を流動させながら、８５０℃を超え１０５０℃未満の温度範囲で行う。この熱処理温度が１０５０℃以上では、硫黄成分の分解が進行して上記焼結の抑制効果が不十分になる。その結果、熱処理によって生成される酸化ニッケル微粉末同士の焼結が顕著になり、その結合力も増大するので、後段の解砕工程での酸化ニッケル微粉末の焼結体の解砕が困難になり、解砕できたとしても比表面積が広い微細な酸化ニッケル微粉末が得られにくくなる。逆に、上記水酸化ニッケル粒子の熱処理温度が８５０℃以下の場合は、硫酸塩等の硫黄成分の分解による硫黄成分の揮発が不十分となり、水酸化ニッケル中に硫黄成分が残留するため、酸化ニッケル微粉末の硫黄品位が５０質量ｐｐｍを超えるおそれがある。
[Heat treatment process]
The sulfur-containing nickel hydroxide particles produced in the neutralization step are then heat-treated in the heat treatment step to produce nickel oxide powder. This heat treatment is performed in a temperature range of more than 850 ° C and less than 1050 ° C while flowing nickel hydroxide particles in a non-reducing atmosphere. When the heat treatment temperature is 1050 ° C. or higher, the decomposition of the sulfur component proceeds and the effect of suppressing the sintering becomes insufficient. As a result, the sintering of the nickel oxide fine powders produced by the heat treatment becomes remarkable, and the bonding force thereof also increases, so that it becomes difficult to crush the sintered body of the nickel oxide fine powders in the subsequent crushing step. Even if it can be crushed, it becomes difficult to obtain fine nickel oxide fine powder having a large specific surface area. On the contrary, when the heat treatment temperature of the nickel hydroxide particles is 850 ° C. or lower, the sulfur component volatilizes insufficiently due to the decomposition of the sulfur component such as sulfate, and the sulfur component remains in the nickel hydroxide, so that oxidation occurs. The sulfur grade of nickel fine powder may exceed 50% by mass ppm.
上記熱処理時の雰囲気は、非還元性雰囲気であれば特に限定はないが、経済性を考慮すると大気雰囲気とすることが好ましい。また、熱処理の際に水酸基の脱離により発生する水蒸気や上記の揮発した硫黄成分を効率よく排出するため、この熱処理工程では水酸化ニッケル粒子の処理量に応じて非還元性ガス、好ましくは空気の通気量の調整を行っている。 The atmosphere at the time of the heat treatment is not particularly limited as long as it is a non-reducing atmosphere, but it is preferably an air atmosphere in consideration of economy. Further, in order to efficiently discharge the water vapor generated by the desorption of hydroxyl groups and the above-mentioned volatilized sulfur component during the heat treatment, a non-reducing gas, preferably air, is used in this heat treatment step depending on the amount of nickel hydroxide particles to be treated. The air volume is being adjusted.
具体的には、単位時間に処理される水酸化ニッケル粒子１ｇ当たり、非還元性ガスの単位時間の通気量を５〜１５０ＮＬに調整している。ここで単位ＮＬは、０℃、１気圧の標準状態に換算した体積である。上記の非還元性ガスの通気量／水酸化ニッケル粒子の処理量（以降、単に通気量／処理量と表す）の値は１５〜５０ＮＬ／ｇが好ましく、１５〜３０ＮＬ／ｇがより好ましい。尚、非還元性ガスの通気量は、例えば体積流量計を用いて設定することができる。 Specifically, the aeration amount of the non-reducing gas per unit time is adjusted to 5 to 150 NL per 1 g of nickel hydroxide particles treated per unit time. Here, the unit NL is a volume converted to a standard state of 0 ° C. and 1 atm. The value of the aeration amount of the non-reducing gas / the treatment amount of the nickel hydroxide particles (hereinafter, simply referred to as the aeration amount / treatment amount) is preferably 15 to 50 NL / g, and more preferably 15 to 30 NL / g. The aeration amount of the non-reducing gas can be set by using, for example, a volume flow meter.
この通気量／処理量の値は、大きくなるほど水酸化ニッケル粒子に含有する硫黄成分の揮発が促進され、酸化ニッケル微粉末の硫黄品位が低下する。通気量／処理量の値が５ＮＬ／ｇ未満では、酸化ニッケル微粉末の硫黄品位が５０質量ｐｐｍを超えることがある。通気量／処理量の値が３０ＮＬ／ｇ程度以上になると酸化ニッケル微粉末の更なる硫黄品位の低下は望めなくなり、その一方で熱処理温度を維持するために供給する非還元性ガスを予備加熱する等のコストが顕著になる。通気量／処理量の値が１５０ＮＬ／ｇを超えると、この供給する非還元性ガスの予備加熱のための設備コストやランニングコストが膨大になるので好ましくない。 The larger the aeration amount / treatment amount value, the more the volatilization of the sulfur component contained in the nickel hydroxide particles is promoted, and the sulfur grade of the nickel oxide fine powder is lowered. If the aeration rate / treatment volume value is less than 5 NL / g, the sulfur grade of the nickel oxide fine powder may exceed 50 mass ppm. When the value of the aeration amount / treatment amount becomes about 30 NL / g or more, further deterioration of the sulfur quality of the nickel oxide fine powder cannot be expected, while the non-reducing gas supplied to maintain the heat treatment temperature is preheated. Etc. will be noticeable. If the value of the aeration amount / treatment amount exceeds 150 NL / g, the equipment cost and running cost for preheating the non-reducing gas to be supplied become enormous, which is not preferable.
上記の通気量／処理量を所定の値に維持して通気を行いながら熱処理を行っても、気流にさらされている水酸化ニッケル粒子と気流にさらされていない水酸化ニッケル粒子が存在すると、熱処理により発生する水蒸気や硫黄成分の排出が不十分になり、想定した硫黄品位が得られにくくなることがある。特に硫黄成分の代表例である硫酸ニッケルは前述したように分解温度が８４８℃と高いため、十分に通気を行ったとしても熱処理後の酸化ニッケル粉末の硫黄品位が高くなってしまうことがある。 Even if the heat treatment is performed while maintaining the above air flow rate / treatment amount at a predetermined value and performing heat treatment, if there are nickel hydroxide particles exposed to the air flow and nickel hydroxide particles not exposed to the air flow, Insufficient discharge of water vapor and sulfur components generated by heat treatment may make it difficult to obtain the expected sulfur grade. In particular, nickel sulfate, which is a typical example of the sulfur component, has a high decomposition temperature of 848 ° C. as described above, so that the sulfur grade of nickel oxide powder after heat treatment may be high even if sufficient aeration is performed.
そこで、本発明の一具体例の製造方法では、水酸化ニッケル粒子を流動させながら熱処理を行っている。これにより、熱処理中の水酸化ニッケル粒子群で構成される流動体は、直接気流にさらされる表面側部分が絶えず内側部分と入れ替わるので、水酸化ニッケル粒子群に対して均一に熱処理を施すことが可能になる。このように熱処理中の水酸化ニッケル粒子群が良好な流動状態を維持するには、水酸化ニッケル粒子群のＤ９０が５〜６０μｍの範囲内にあることが好ましい。水酸化ニッケル粒子群のＤ９０がこの範囲内にあることで、上記説明した硫黄成分の働きとの相乗効果により、熱処理により得られる酸化ニッケル微粉末の焼結による流動性の低下が抑えられ、熱処理中の良好な流動性が維持される。 Therefore, in the production method of a specific example of the present invention, heat treatment is performed while flowing nickel hydroxide particles. As a result, in the fluid composed of the nickel hydroxide particle group during the heat treatment, the surface side portion exposed to the direct air flow is constantly replaced with the inner portion, so that the nickel hydroxide particle group can be uniformly heat-treated. It will be possible. In order to maintain a good flow state of the nickel hydroxide particle group during the heat treatment, it is preferable that the D90 of the nickel hydroxide particle group is in the range of 5 to 60 μm. When the D90 of the nickel hydroxide particle group is within this range, the synergistic effect with the action of the sulfur component described above suppresses the decrease in fluidity due to the sintering of the nickel oxide fine powder obtained by the heat treatment, and the heat treatment is performed. Good fluidity inside is maintained.
上記の熱処理を行う装置は熱処理中の水酸化ニッケル粒子群を良好に流動させることができるのであれば特に限定はなく、例えば水酸化ニッケル粒子の処理量が少ない場合は、上記した非還元性ガスの気流により水酸化ニッケル粒子群を流動させるような装置でもよい。一方、水酸化ニッケル粒子の処理量が多い場合には、例えば流動焙焼炉や転動炉を用いることが好ましい。 The apparatus for performing the heat treatment is not particularly limited as long as the nickel hydroxide particles during the heat treatment can be satisfactorily flowed. For example, when the amount of nickel hydroxide particles to be treated is small, the non-reducing gas described above is used. The device may be such that the nickel hydroxide particle group is made to flow by the air flow of the above. On the other hand, when the amount of nickel hydroxide particles to be processed is large, it is preferable to use, for example, a fluidized roasting furnace or a rolling mill.
転動炉を用いる場合は、中心軸を中心として回転する円筒状のいわゆるレトルトの内壁部に、レトルトの回転に伴って処理対象物である流動体をある程度の高さまで持ち上げて落下させることで撹拌を行う羽根等の突起物を設けるのが好ましい。この突起物がないと、処理対象物が十分に流動しない場合があり、酸化ニッケル微粒子の品質にばらつきが生じるおそれがある。 When using a rolling furnace, the fluid that is the object to be processed is lifted to a certain height and dropped onto the inner wall of a cylindrical so-called retort that rotates around the central axis to stir. It is preferable to provide a protrusion such as a blade for performing the above. Without these protrusions, the object to be treated may not flow sufficiently, and the quality of the nickel oxide fine particles may vary.
熱処理時間は、熱処理温度や処理量等の熱処理条件に応じて適宜設定することができ、例えば熱処理後の酸化ニッケル微粉末の比表面積が所望の範囲となるように設定すればよい。前述したように、水酸化ニッケルに含有される硫黄成分の働きにより、熱処理により生成される酸化ニッケルは微細となり、焼結体が含まれる場合であってもその結合力は比較的弱いので容易に解砕することができる。 The heat treatment time can be appropriately set according to the heat treatment conditions such as the heat treatment temperature and the treatment amount. For example, the specific surface area of the nickel oxide fine powder after the heat treatment may be set within a desired range. As described above, nickel oxide produced by heat treatment becomes fine due to the action of the sulfur component contained in nickel hydroxide, and even if a sintered body is contained, the bonding force is relatively weak, so that it is easy. Can be crushed.
この焼結体の粉砕では、解砕後に得られる酸化ニッケル微粉末の比表面積は、解砕前の酸化ニッケル粉末の比表面積に対して約１.５〜２.５ｍ２／ｇ程度増加するだけである。従って、熱処理後の酸化ニッケル粉末の比表面積に基づいて熱処理条件を設定することができる。すなわち、上記したように熱処理温度と通気量／処理量を適宜設定することにより、酸化ニッケル微粉末の硫黄品位と比表面積を容易に制御できる。 In the crushing of this sintered body, the specific surface area of the nickel oxide fine powder obtained after crushing is only increased by about 1.5 to 2.5 m 2 / g with respect to the specific surface area of the nickel oxide powder before crushing. Is. Therefore, the heat treatment conditions can be set based on the specific surface area of the nickel oxide powder after the heat treatment. That is, the sulfur grade and the specific surface area of the nickel oxide fine powder can be easily controlled by appropriately setting the heat treatment temperature and the aeration amount / treatment amount as described above.
［解砕工程］
上記熱処理工程で生成された酸化ニッケル微粉末は必要に応じて解砕工程で処理され、これにより熱処理の際に形成され得る酸化ニッケル微粉末の焼結体を解砕することができる。上記熱処理工程では水酸化ニッケル粒子中の水酸基が離脱して酸化ニッケル粉末が形成されるが、その際、粒径の微細化が起こると共に、硫酸成分により抑制されてはいるものの、熱処理温度や熱処理時間によっては酸化ニッケル微粉末同士の焼結がある程度進行する。熱処理後の酸化ニッケル粉末に対して解砕処理を行うことで、この焼結体が破壊されるため、極めて微細な酸化ニッケル微粉末が得られる。
[Crushing process]
The nickel oxide fine powder produced in the heat treatment step is treated in a crushing step if necessary, whereby the sintered body of the nickel oxide fine powder that can be formed during the heat treatment can be crushed. In the above heat treatment step, the hydroxyl groups in the nickel hydroxide particles are separated to form nickel oxide powder. At that time, the particle size is refined and the heat treatment is suppressed by the sulfuric acid component, but the heat treatment temperature and heat treatment are performed. Depending on the time, the sintering of the nickel oxide fine powders progresses to some extent. By crushing the nickel oxide powder after the heat treatment, the sintered body is destroyed, so that extremely fine nickel oxide fine powder can be obtained.
解砕方法としては、一般的にビーズミルやボールミル等の解砕メディアを用いる解砕法、又はジェットミル等の解砕メディアを用いない流体エネルギーによる解砕法があるが、上記の熱処理後の酸化ニッケル粉末の解砕処理においては、後者の解砕メディアを用いない流体エネルギーによる解砕法を採用することが好ましい。なぜなら、解砕メディアを用いると解砕自体は容易となるものの、ジルコニア等の解砕メディアを構成している成分が不純物として混入するおそれがあるからである。特に、電子部品用として酸化ニッケル微粉を用いる場合には、解砕メディアを用いない解砕方法を採用することが好ましい。 As a crushing method, there are generally a crushing method using a crushing medium such as a bead mill or a ball mill, or a crushing method using fluid energy without using a crushing medium such as a jet mill. In the crushing process of the above, it is preferable to adopt the latter crushing method using fluid energy without using a crushing medium. This is because, although crushing itself is facilitated by using crushing media, components constituting the crushing media such as zirconia may be mixed as impurities. In particular, when nickel oxide fine powder is used for electronic parts, it is preferable to adopt a crushing method that does not use a crushing medium.
低減すべき不純物がジルコニウムのみであるならば、解砕メディアにジルコニア等のジルコニウムを含有しないものを用いて解砕することが考えられるが、この場合であっても解砕メディアを構成する他の不純物が混入し得るので、結果的に低不純物品位の酸化ニッケル微粉末を得るのが困難になる。更に、解砕メディアがイットリア安定化ジルコニアに代表されるジルコニウムを含有しない場合は、強度や耐摩耗性が不十分になるため、この観点からも解砕メディアを用いない解砕法が望ましい。 If the only impurity to be reduced is zirconium, it is conceivable to use a crushing medium that does not contain zirconium, such as zirconia, for crushing, but even in this case, other crushing media constituting the crushing media may be used. Since impurities can be mixed in, it becomes difficult to obtain nickel oxide fine powder having a low impurity grade as a result. Further, when the crushing media does not contain zirconium typified by yttria-stabilized zirconia, the strength and wear resistance become insufficient. Therefore, from this viewpoint as well, a crushing method without using the crushing media is desirable.
解砕メディアを用いない解砕法としては、ガス（気体）や溶媒（液体）を用い、それら流体により粉体の粒子同士を衝突させる方法や、液体などの溶媒により粉体にせん断力をかける方法、溶媒のキャビテーションによる衝撃力を用いる方法等がある。粉体の粒子同士を衝突させる解砕法を適用した装置としては、例えば、乾式ジェットミルや湿式ジェットミルがあり、具体的には前者にはナノグラインディングミル（登録商標）や、クロスジェットミル（登録商標）、後者にはアルティマイザー（登録商標）、スターバースト（登録商標）等がある。また、溶媒によりせん断力を与える解砕法を適用した装置としては、例えば、ナノマイザー（登録商標）等があり、溶媒のキャビテーションによる衝撃力を用いた解砕法を適用した装置としては、例えば、ナノメーカー（登録商標）等がある。 As a crushing method that does not use a crushing medium, a method of using a gas (gas) or a solvent (liquid) and causing the powder particles to collide with each other by the fluid, or a method of applying a shearing force to the powder with a solvent such as a liquid. , There is a method of using the impact force due to the cavitation of the solvent. Devices to which the crushing method of colliding powder particles collide with each other include, for example, a dry jet mill and a wet jet mill. Specifically, the former includes a nano grinding mill (registered trademark) and a cross jet mill (registered trademark). (Registered trademark), the latter includes Ultimater (registered trademark), Starburst (registered trademark), etc. Further, as an apparatus to which a crushing method applying a shearing force by a solvent is applied, for example, there is a nanomizer (registered trademark), and as an apparatus to which an impact force by cavitation of a solvent is applied, for example, a nanomaker (Registered trademark), etc.
上記解砕法のうち、粉体の粒子同士を衝突させる方法が、不純物混入のおそれが少なく、比較的大きな解砕力が得られることから好ましく、乾式によるものが特に好ましい。乾式が好ましい理由は、湿式解砕では解砕後に行う乾燥処理の際に酸化ニッケル微粉末が再凝集するおそれがあるが、乾式解砕ではこのような再凝集の問題が生じにくいからである。尚、本発明の一具体例の製造方法では、硫酸ニッケルを原料とするため、塩素除去のために洗浄を行う必要が特にない。従って乾燥工程の不要な乾式解砕を採用することができるため、製造コストを抑えることができる。上記の解砕条件には特に限定がなく、通常の条件の範囲内での調整により目的とする粒度分布の酸化ニッケル微粉末を容易に得ることができる。これにより、フェライト部品などの電子部品材料として好適な分散性に優れた微細な酸化ニッケル微粉末を得ることができる。 Of the above crushing methods, the method of colliding powder particles with each other is preferable because there is little risk of impurities being mixed in and a relatively large crushing force can be obtained, and the dry method is particularly preferable. The reason why the dry method is preferable is that the nickel oxide fine powder may reaggregate during the drying treatment performed after the crushing in the wet crushing method, but the problem of such reaggregation does not easily occur in the dry crushing method. In addition, in the production method of one specific example of the present invention, since nickel sulfate is used as a raw material, it is not particularly necessary to perform cleaning for removing chlorine. Therefore, since dry crushing that does not require a drying step can be adopted, the manufacturing cost can be suppressed. The above-mentioned crushing conditions are not particularly limited, and nickel oxide fine powder having a target particle size distribution can be easily obtained by adjusting within the range of normal conditions. As a result, it is possible to obtain fine nickel oxide fine powder having excellent dispersibility, which is suitable as a material for electronic parts such as ferrite parts.
［酸化ニッケル微粉末の物性］
以上説明した本発明の一具体例の酸化ニッケル微粉末の製造方法により製造される酸化ニッケル微粉末は、原料から不可避不純物として混入する以外に塩素が混入する工程を含まないので、塩素品位が極めて低い。加えて、硫黄品位が制御されると共に、ナトリウム等のアルカリ金属の品位が低く、比表面積が大きい。具体的には、硫黄品位が５０質量ｐｐｍ以下、塩素品位が５０質量ｐｐｍ以下、総アルカリ金属の品位が１００質量ｐｐｍ以下である。従って、電子部品用、特にフェライト部品用の材料や固体酸化物形燃料電池の電極用材料として好適である。尚、固体酸化物形燃料電池の電極用材料としては、硫黄品位が１００質量ｐｐｍ以下であることが好ましいとされている。
[Physical characteristics of nickel oxide fine powder]
The nickel oxide fine powder produced by the method for producing nickel oxide fine powder of one specific example of the present invention described above does not include a step of mixing chlorine other than being mixed as an unavoidable impurity from the raw material, so that the chlorine grade is extremely high. Low. In addition, the sulfur grade is controlled, the grade of the alkali metal such as sodium is low, and the specific surface area is large. Specifically, the sulfur grade is 50 mass ppm or less, the chlorine grade is 50 mass ppm or less, and the total alkali metal grade is 100 mass ppm or less. Therefore, it is suitable as a material for electronic parts, particularly for ferrite parts, and as a material for electrodes of solid oxide fuel cells. As a material for electrodes of solid oxide fuel cells, it is said that the sulfur grade is preferably 100 mass ppm or less.
また、上記した本発明の一具体例の酸化ニッケル微粉末の製造方法においては、マグネシウム等の第２族元素を添加する工程を含まないので、これらの元素が不純物として含まれることは実質的にない。更に、解砕メディアを使用せずに解砕する場合はジルコニアも含まれなくなるので、ジルコニア品位及び第２族元素品位を３０質量ｐｐｍ以下にすることができる。 Further, since the method for producing the nickel oxide fine powder of one specific example of the present invention does not include the step of adding a Group 2 element such as magnesium, it is substantially possible that these elements are contained as impurities. Absent. Further, when crushing without using a crushing medium, zirconia is not contained, so that the zirconia grade and the Group 2 element grade can be reduced to 30 mass ppm or less.
上記した本発明の一具体例の酸化ニッケル微粉末の製造方法で作製した酸化ニッケル微粉末は、レーザー散乱法で測定したＤ９０（粒度分布曲線における粒子量の体積積算９０％での粒径）が２μｍ以下であることが好ましく、０.２〜１.０μｍがより好ましく、０.４〜０.６μｍが最も好ましい。尚、酸化ニッケル微粉末は電子部品等の製造工程において、他の材料と混合されるときに解砕されて小さくなることがあり、レーザー散乱法で測定したＤ９０も小さくなるが、この解砕によって比表面積が大きくなる可能性は低いため、酸化ニッケル微粉末の比表面積で評価を行う方がより確実である。更に、本発明の実施形態の酸化ニッケル微粉末の製造方法においては、湿式法により製造した水酸化ニッケルを熱処理するため、有害なＳＯｘが大量に発生することがない。従って、これを除害処理するための高価な設備が不要である。更に熱処理回数も１回で済むので、製造コストを低く抑えることができる。 The nickel oxide fine powder produced by the method for producing the nickel oxide fine powder of one specific example of the present invention has a D90 (particle size at a volume integration of 90% of the particle amount in the particle size distribution curve) measured by the laser scattering method. It is preferably 2 μm or less, more preferably 0.2 to 1.0 μm, and most preferably 0.4 to 0.6 μm. Nickel oxide fine powder may be crushed and reduced when mixed with other materials in the manufacturing process of electronic parts, etc., and D90 measured by the laser scattering method is also reduced. Since it is unlikely that the specific surface area will increase, it is more reliable to evaluate by the specific surface area of the nickel oxide fine powder. Further, in the method for producing fine nickel oxide powder according to the embodiment of the present invention, since the nickel hydroxide produced by the wet method is heat-treated, a large amount of harmful SOx is not generated. Therefore, expensive equipment for detoxifying this is not required. Further, since the number of heat treatments is only one, the manufacturing cost can be kept low.
次に、実施例及び比較例を挙げて本発明を説明するが、本発明はこれらの実施例等によってなんら限定されるものではない。尚、以下の実施例及び比較例の塩素品位の分析は、分析対象物を塩素の揮発を抑制できる密閉容器内にてマイクロ波照射下で硝酸に溶解し、硝酸銀を加えて塩化銀を沈殿させ、得られた沈殿物中の塩素を蛍光Ｘ線定量分析装置（ＰＡＮａｌｙｔｉｃａｌ社製 Ｍａｇｉｘ）を用いて検量線法で評価することによって行った。硫黄品位の分析は、分析対象物を硝酸に溶解した後、ＩＣＰ発光分光分析装置（セイコー社製 ＳＰＳ−３０００）によって行った。ナトリウム品位の分析は、分析対象物を硝酸に溶解した後、原子吸光装置（日立ハイテク社製 Ｚ−２３００）により評価することによって行った。水酸化ニッケル粒子及び酸化ニッケル微粉末の粒径は、レーザー散乱法により測定し、その粒度分布から体積積算９０％での粒径Ｄ９０を求めた。比表面積の分析は、窒素ガス吸着によるＢＥＴ法により求めた。
［実施例１］
邪魔板とオーバーフロー口を有する撹拌機構付きの容量２Ｌの反応槽において、純水と水酸化ナトリウムとからなるｐＨ８.５に調整した水酸化ナトリウム水溶液２Ｌを調製し、十分に攪拌した。次に、硫酸ニッケルを純水に溶解してニッケル濃度１２０ｇ／Ｌのニッケル水溶液を調製した。また、添加用水酸化ナトリウム水溶液として１２.５質量％の水酸化ナトリウム水溶液を用意した。これらニッケル水溶液と添加用水酸化ナトリウム水溶液とを上記反応槽内の水酸化ナトリウム水溶液に同時並行的且つ連続的に添加して混合した。
Next, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples and the like. In the chlorine grade analysis of the following examples and comparative examples, the object to be analyzed is dissolved in nitric acid under microwave irradiation in a closed container capable of suppressing the volatilization of chlorine, and silver nitrate is added to precipitate silver chloride. , Chlorine in the obtained precipitate was evaluated by a calibration curve method using a fluorescent X-ray quantitative analyzer (Magic manufactured by PANalytical Co., Ltd.). The sulfur grade was analyzed by dissolving the analysis object in nitric acid and then using an ICP emission spectrophotometer (SPS-3000 manufactured by Seiko Corporation). The sodium grade analysis was performed by dissolving the analysis object in nitric acid and then evaluating it with an atomic absorption spectrophotometer (Z-2300 manufactured by Hitachi High-Tech). The particle size of the nickel hydroxide particles and the nickel oxide fine powder was measured by a laser scattering method, and the particle size D90 at a volume integration of 90% was determined from the particle size distribution. The specific surface area was analyzed by the BET method by adsorbing nitrogen gas.
[Example 1]
In a reaction vessel having a capacity of 2 L and having a baffle plate and an overflow port and having a stirring mechanism, 2 L of a sodium hydroxide aqueous solution composed of pure water and sodium hydroxide adjusted to pH 8.5 was prepared and sufficiently stirred. Next, nickel sulfate was dissolved in pure water to prepare a nickel aqueous solution having a nickel concentration of 120 g / L. Further, a 12.5% by mass sodium hydroxide aqueous solution was prepared as the sodium hydroxide aqueous solution for addition. These nickel aqueous solutions and the sodium hydroxide aqueous solution for addition were added simultaneously and continuously to the sodium hydroxide aqueous solution in the reaction vessel and mixed.
その際、反応槽内のｐＨを８.５を中心としてその変動幅が絶対値で０.２以内となるように水酸化ナトリウム水溶液の流量で調整した。また、ニッケル水溶液は５ｍＬ／分の流量で添加することによって、水酸化ニッケル粒子の滞留時間を約３時間に調整した。この時、ニッケル水溶液と添加用水酸化ナトリウム水溶液が各々反応槽内の液と混合する部分では乱流状態になっていた。この中和反応中は、反応槽内の液温を６０℃に調整し、攪拌翼を７００ｒｐｍで回転させて撹拌した。この連続晶析法により水酸化ニッケル粒子の沈殿物を晶析させ、この沈殿物をオーバーフローにより回収した。 At that time, the pH in the reaction vessel was adjusted by the flow rate of the sodium hydroxide aqueous solution so that the fluctuation range was within 0.2 in absolute value around 8.5. The residence time of the nickel hydroxide particles was adjusted to about 3 hours by adding the nickel aqueous solution at a flow rate of 5 mL / min. At this time, the portion where the nickel aqueous solution and the sodium hydroxide aqueous solution for addition were mixed with the liquid in the reaction vessel was in a turbulent state. During this neutralization reaction, the liquid temperature in the reaction vessel was adjusted to 60 ° C., and the stirring blade was rotated at 700 rpm for stirring. A precipitate of nickel hydroxide particles was crystallized by this continuous crystallization method, and the precipitate was recovered by overflow.
上記のオーバーフローにより回収した水酸化ニッケル粒子を含むスラリーに対してヌッチェによる濾過と保持時間３０分の純水レパルプを１０回繰り返して、水酸化ニッケル粒子を含む濾過ケーキを得た。この濾過ケーキを、送風乾燥機を用いて１１０℃の大気中にて２４時間乾燥したところ、そのＤ９０は４６μｍであり、硫黄（Ｓ）品位は１.４質量％であった。 The slurry containing nickel hydroxide particles recovered by the above overflow was filtered by Nutche and pure water repulp having a holding time of 30 minutes was repeated 10 times to obtain a filtered cake containing nickel hydroxide particles. When this filtered cake was dried in the air at 110 ° C. for 24 hours using a blower dryer, its D90 was 46 μm and the sulfur (S) grade was 1.4% by mass.
得られた水酸化ニッケル粒子２００ｇを転動炉に供給し、９４０℃の大気雰囲気下で５時間熱処理して酸化ニッケル微粉末の焼結体を得た（熱処理工程）。転動炉には、内壁部に突起が付設された円筒状のレトルト（内径１２０ｍｍ、長さ１５０ｍｍ）を用い、このレトルトを１ｒｐｍで回転させることで、熱処理対象物である水酸化ニッケル粒子を流動させながら熱処理した。その際、コンプレッサーにより空気を２００ＮＬ／ｈの流量でレトルト内にその一端部から導入し、他端部から排ガスを排出させることでレトルト内に空気を通気した。この時、単位時間当たりの水酸化ニッケル粒子の処理量は２００／５＝４０ｇ／ｈとなるので、通気量（ＮＬ）／処理量（ｇ）の値は２００／４０＝５になる。 200 g of the obtained nickel hydroxide particles were supplied to a rolling mill and heat-treated in an air atmosphere at 940 ° C. for 5 hours to obtain a sintered body of nickel oxide fine powder (heat treatment step). A cylindrical retort pouch (inner diameter 120 mm, length 150 mm) with protrusions on the inner wall is used for the rolling furnace, and by rotating this retort at 1 rpm, nickel hydroxide particles, which are the objects to be heat-treated, flow. The heat treatment was carried out. At that time, air was introduced into the retort at a flow rate of 200 NL / h by a compressor from one end thereof, and exhaust gas was discharged from the other end to ventilate the air into the retort. At this time, since the processing amount of the nickel hydroxide particles per unit time is 200/5 = 40 g / h, the value of the aeration amount (NL) / processing amount (g) is 200/40 = 5.
このようにして熱処理された酸化ニッケル微粉末から任意に分取した１５０ｇをナノグラインディングミル（登録商標、徳寿工作所製）にてプッシャーノズル圧力１.０ＭＰａ、グラインディング圧力０.９ＭＰａにて粉砕した（解砕工程）。このようにして作製した酸化ニッケル微粉末は、硫黄（Ｓ）品位が４０質量ｐｐｍ、塩素（Ｃｌ）品位が５０質量ｐｐｍ未満、ナトリウム（Ｎａ）品位が１００質量ｐｐｍ未満であった。また、比表面積は３.６ｍ２／ｇ、Ｄ９０は０.４４μｍであった。 150 g of the nickel oxide fine powder heat-treated in this manner is pulverized with a nano grinding mill (registered trademark, manufactured by Tokuju Kosakusho) at a pusher nozzle pressure of 1.0 MPa and a grinding pressure of 0.9 MPa. (Crushing process). The nickel oxide fine powder thus produced had a sulfur (S) grade of less than 40 mass ppm, a chlorine (Cl) grade of less than 50 mass ppm, and a sodium (Na) grade of less than 100 mass ppm. The specific surface area was 3.6 m 2 / g, and D90 was 0.44 μm.
［実施例２］
６００ＮＬ／ｈの空気をレトルト内に導入して通気量（ＮＬ）／処理量（ｇ）が１５となるようにした以外は実施例１と同様にして酸化ニッケル微粉末を作製した。得られた酸化ニッケル微粉末は、硫黄品位が２０質量ｐｐｍ、塩素品位が５０質量ｐｐｍ未満、ナトリウム品位が１００質量ｐｐｍ未満であった。また、比表面積は３.４ｍ２／ｇ、Ｄ９０は０.４６μｍであった。
[Example 2]
Nickel oxide fine powder was prepared in the same manner as in Example 1 except that 600 NL / h of air was introduced into the retort so that the aeration amount (NL) / treatment amount (g) was 15. The obtained nickel oxide fine powder had a sulfur grade of 20 mass ppm, a chlorine grade of less than 50 mass ppm, and a sodium grade of less than 100 mass ppm. The specific surface area was 3.4 m 2 / g, and D90 was 0.46 μm.
［実施例３］
１２００ＮＬ／ｈの空気をレトルト内に導入して通気量（ＮＬ）／処理量（ｇ）が３０となるようにした以外は実施例１と同様にして酸化ニッケル微粉末を作製した。得られた酸化ニッケル微粉末は、硫黄品位が１０質量ｐｐｍ、塩素品位が５０質量ｐｐｍ未満、ナトリウム品位が１００質量ｐｐｍ未満であった。また、比表面積は３.２ｍ２／ｇ、Ｄ９０は０.５０μｍであった。
[Example 3]
Nickel oxide fine powder was prepared in the same manner as in Example 1 except that 1200 NL / h of air was introduced into the retort so that the aeration amount (NL) / treatment amount (g) was 30. The obtained nickel oxide fine powder had a sulfur grade of less than 10 mass ppm, a chlorine grade of less than 50 mass ppm, and a sodium grade of less than 100 mass ppm. The specific surface area was 3.2 m 2 / g, and D90 was 0.50 μm.
［実施例４］
６０００ＮＬ／ｈの空気をレトルト内に導入して通気量（ＮＬ）／処理量（ｇ）が１５０となるようにした以外は実施例１と同様にして酸化ニッケル微粉末を作製した。得られた酸化ニッケル微粉末は、硫黄品位が１０質量ｐｐｍ、塩素品位が５０質量ｐｐｍ未満、ナトリウム品位が１００質量ｐｐｍ未満であった。また、比表面積は３.１ｍ２／ｇ、Ｄ９０は０.５５μｍであった。
[Example 4]
Nickel oxide fine powder was prepared in the same manner as in Example 1 except that 6000 NL / h of air was introduced into the retort so that the aeration amount (NL) / treatment amount (g) was 150. The obtained nickel oxide fine powder had a sulfur grade of less than 10 mass ppm, a chlorine grade of less than 50 mass ppm, and a sodium grade of less than 100 mass ppm. The specific surface area was 3.1 m 2 / g, and D90 was 0.55 μm.
［実施例５］
熱処理温度を８６０℃とした以外は実施例３と同様にして酸化ニッケル微粉末を作製した。得られた酸化ニッケル微粉末は、硫黄品位が５０質量ｐｐｍ、塩素品位が５０質量ｐｐｍ未満、ナトリウム品位が１００質量ｐｐｍ未満であった。また比表面積は３.９ｍ２／ｇ、Ｄ９０は０.４０μｍであった。
[Example 5]
Nickel oxide fine powder was prepared in the same manner as in Example 3 except that the heat treatment temperature was set to 860 ° C. The obtained nickel oxide fine powder had a sulfur grade of less than 50 mass ppm, a chlorine grade of less than 50 mass ppm, and a sodium grade of less than 100 mass ppm. The specific surface area was 3.9 m 2 / g, and D90 was 0.40 μm.
［実施例６］
熱処理温度を１０４０℃とした以外は実施例３と同様にして酸化ニッケル微粉末を作製した。得られた酸化ニッケル微粉末は、硫黄品位が１０質量ｐｐｍ未満、塩素品位が５０質量ｐｐｍ未満、ナトリウム品位が１００質量ｐｐｍ未満であった。また比表面積は３.０ｍ２／ｇ、Ｄ９０は０.６０μｍであった。
[Example 6]
Nickel oxide fine powder was prepared in the same manner as in Example 3 except that the heat treatment temperature was set to 1040 ° C. The obtained nickel oxide fine powder had a sulfur grade of less than 10 mass ppm, a chlorine grade of less than 50 mass ppm, and a sodium grade of less than 100 mass ppm. The specific surface area was 3.0 m 2 / g, and D90 was 0.60 μm.
［実施例７］
実施例１の中和工程と同様にして得た水酸化ニッケル粒子１０ｇを、石英管を垂直（開口部が上下方向）に配した管状炉の中央部に設置したハニカム皿に積載し、９００℃の大気雰囲気下で３時間熱処理して酸化ニッケル微粉末の焼結体を得た（熱処理工程）。その際、送風機を用いて空気を２４ＮＬ／ｈの流量で下側開口部から導入し、上側開口部から排ガスを排出させることで管状炉内に空気を通気した。この時、単位時間当たりの水酸化ニッケル粒子の処理量は１０／３＝３.３３ｇ／ｈとなるので、通気量（ＮＬ）／処理量（ｇ）の値は２４／３.３３＝７.２になる。尚、通気の際は水酸化ニッケル粒子がハニカム皿上で流動していた。
[Example 7]
10 g of nickel hydroxide particles obtained in the same manner as in the neutralization step of Example 1 was loaded on a honeycomb dish installed in the center of a tubular furnace in which quartz tubes were arranged vertically (openings are in the vertical direction), and the temperature was 900 ° C. Heat treatment was performed for 3 hours in the air atmosphere of the above to obtain a sintered body of fine nickel oxide powder (heat treatment step). At that time, air was introduced from the lower opening at a flow rate of 24 NL / h using a blower, and exhaust gas was discharged from the upper opening to ventilate the air into the tube furnace. At this time, the treated amount of nickel hydroxide particles per unit time is 10/3 = 3.33 g / h, so the value of the aeration amount (NL) / treated amount (g) is 24 / 3.33 = 7. It becomes 2. At the time of ventilation, nickel hydroxide particles were flowing on the honeycomb dish.
得られた酸化ニッケル微粉末の焼結体を乳鉢により解砕した。解砕した酸化ニッケル微粉末は、硫黄品位が４０質量ｐｐｍ、塩素品位が５０質量ｐｐｍ未満、ナトリウム品位が１００質量ｐｐｍ未満であった。また、比表面積は３.６ｍ２／ｇ、Ｄ９０は０.５６μｍであった。 The obtained sintered body of nickel oxide fine powder was crushed in a mortar. The crushed nickel oxide fine powder had a sulfur grade of 40 mass ppm, a chlorine grade of less than 50 mass ppm, and a sodium grade of less than 100 mass ppm. The specific surface area was 3.6 m 2 / g, and D90 was 0.56 μm.
［比較例１］
空気を通気しない以外は実施例１と同様にして酸化ニッケル微粉末を作製した。この場合、通気量（ＮＬ）／処理量（ｇ）はゼロとなる。得られた酸化ニッケル微粉末は、硫黄品位が８０質量ｐｐｍ、塩素品位が５０質量ｐｐｍ未満、ナトリウム品位が１００質量ｐｐｍ未満であった。また、比表面積は３.６ｍ２／ｇ、Ｄ９０は０.４５μｍであった。
[Comparative Example 1]
Nickel oxide fine powder was prepared in the same manner as in Example 1 except that air was not aerated. In this case, the aeration amount (NL) / treatment amount (g) becomes zero. The obtained nickel oxide fine powder had a sulfur grade of 80 mass ppm, a chlorine grade of less than 50 mass ppm, and a sodium grade of less than 100 mass ppm. The specific surface area was 3.6 m 2 / g, and D90 was 0.45 μm.
［比較例２］
実施例１の中和工程と同様にして得た水酸化ニッケル粒子２００ｇを、内径１２０ｍｍ、長さ１５０ｍｍのアルミナ管に充填し、このアルミナ管を水平（開口部が左右方向）に配した石英管を備えた横型管状炉内に載置した。そして、９４０℃の大気雰囲気下で５時間熱処理して酸化ニッケル微粉末の焼結体を得た（熱処理工程）。その際、送風機を用いて空気を２００ＮＬ／ｈの流量で一方の開口部から導入し、他方の開口部から排ガスを排出させることで管状炉内に空気を通気した。この時、単位時間当たりの水酸化ニッケル粒子の処理量は２００／５＝４０ｇ／ｈとなるので、通気量（ＮＬ）／処理量（ｇ）の値は２００／４０＝５になる。尚、通気の際はアルミナ管内に充填された水酸化ニッケル粒子の流動は観察されなかった。
[Comparative Example 2]
200 g of nickel hydroxide particles obtained in the same manner as in the neutralization step of Example 1 was filled in an alumina tube having an inner diameter of 120 mm and a length of 150 mm, and the alumina tube was arranged horizontally (the opening is in the left-right direction). It was placed in a horizontal tube furnace equipped with. Then, it was heat-treated in an air atmosphere of 940 ° C. for 5 hours to obtain a sintered body of nickel oxide fine powder (heat treatment step). At that time, air was introduced into the tube furnace at a flow rate of 200 NL / h using a blower, and exhaust gas was discharged from the other opening to ventilate the air into the tube furnace. At this time, since the processing amount of the nickel hydroxide particles per unit time is 200/5 = 40 g / h, the value of the aeration amount (NL) / processing amount (g) is 200/40 = 5. During aeration, no flow of nickel hydroxide particles filled in the alumina tube was observed.
以降は実施例１と同様にして解砕して分析を行った。得られた酸化ニッケル微粉末は、硫黄品位が１２０質量ｐｐｍ、塩素品位が５０質量ｐｐｍ未満、ナトリウム品位が１００質量ｐｐｍ未満であった。また、比表面積は３.５ｍ２／ｇ、Ｄ９０は０.５４μｍであった。 After that, it was crushed and analyzed in the same manner as in Example 1. The obtained nickel oxide fine powder had a sulfur grade of 120 mass ppm, a chlorine grade of less than 50 mass ppm, and a sodium grade of less than 100 mass ppm. The specific surface area was 3.5 m 2 / g, and D90 was 0.54 μm.
［比較例３］
熱処理温度を８４０℃とした以外は実施例３と同様にして酸化ニッケル微粉末を作製した。得られた酸化ニッケル微粉末は、硫黄品位が３４０質量ｐｐｍ、塩素品位が５０質量ｐｐｍ未満、ナトリウム品位が１００質量ｐｐｍ未満であった。また比表面積は４.２ｍ２／ｇ、Ｄ９０は０.３８μｍであった。
[Comparative Example 3]
Nickel oxide fine powder was prepared in the same manner as in Example 3 except that the heat treatment temperature was set to 840 ° C. The obtained nickel oxide fine powder had a sulfur grade of 340 mass ppm, a chlorine grade of less than 50 mass ppm, and a sodium grade of less than 100 mass ppm. The specific surface area was 4.2 m 2 / g, and D90 was 0.38 μm.
［比較例４］
熱処理温度を１０６０℃とした以外は実施例３と同様にして酸化ニッケル微粉末を作製した。得られた酸化ニッケル微粉末は、硫黄品位が１０質量ｐｐｍ未満、塩素品位が５０質量ｐｐｍ未満、ナトリウム品位が１００質量ｐｐｍ未満であった。また比表面積は２.３ｍ２／ｇ、Ｄ９０は１.１μｍであった。
[Comparative Example 4]
Nickel oxide fine powder was prepared in the same manner as in Example 3 except that the heat treatment temperature was set to 1060 ° C. The obtained nickel oxide fine powder had a sulfur grade of less than 10 mass ppm, a chlorine grade of less than 50 mass ppm, and a sodium grade of less than 100 mass ppm. The specific surface area was 2.3 m 2 / g, and D90 was 1.1 μm.
上記実施例１〜７及び比較例１〜４について、熱処理条件（温度、時間、及び通気量／処理量）と、得られた酸化ニッケル微粉末の硫黄（Ｓ）品位、塩素（Ｃｌ）品位、ナトリウム（Ｎａ）品位、Ｄ９０、及び比表面積を下記の表１にまとめて示す。 Regarding Examples 1 to 7 and Comparative Examples 1 to 4, the heat treatment conditions (temperature, time, and aeration amount / treatment amount), the sulfur (S) grade, and the chlorine (Cl) grade of the obtained nickel oxide fine powder, The sodium (Na) grade, D90, and specific surface area are summarized in Table 1 below.
上記表１の結果から分るように、実施例１〜７の全てにおいて、硫黄品位が５０質量ｐｐｍ以下に制御されている上、塩素品位が５０質量ｐｐｍ未満、ナトリウム品位が１００質量ｐｐｍ未満となっている。また、比表面積が３.０ｍ２／ｇ以上、４.０ｍ２／ｇ未満、Ｄ９０が０.６０μｍ以下であり、微細な酸化ニッケル微粉末が得られていることが分る。 As can be seen from the results in Table 1 above, in all of Examples 1 to 7, the sulfur grade is controlled to 50 mass ppm or less, the chlorine grade is less than 50 mass ppm, and the sodium grade is less than 100 mass ppm. It has become. Further, the specific surface area is 3.0 m 2 / g or more and less than 4.0 m 2 / g, and the D90 is 0.60 μm or less, and it can be seen that fine nickel oxide fine powder is obtained.
これに対して、比較例１では、通気量（ＮＬ）／処理量（ｇ）が本発明の要件から外れているため硫黄品位が高く、電子部品材料として好適な範囲内となっていない。また、比較例２では水酸化ニッケル粒子を静止させた状態で熱処理を行ったため硫黄品位が高く、比較例３では熱処理の温度が本発明の要件より低温側に外れているため硫黄品位が高く、比較例４では熱処理の温度が本発明の要件より高温側に外れているためＤ９０が大きく、いずれも電子部品材料として好適な範囲内となっていない。
On the other hand, in Comparative Example 1, since the aeration amount (NL) / treatment amount (g) does not meet the requirements of the present invention, the sulfur grade is high and it is not within a suitable range as an electronic component material. Further, in Comparative Example 2, the heat treatment was performed with the nickel hydroxide particles stationary, so that the sulfur grade was high, and in Comparative Example 3, the sulfur grade was high because the heat treatment temperature was lower than the requirement of the present invention. In Comparative Example 4, since the heat treatment temperature deviates from the requirement of the present invention on the high temperature side, D90 is large, and none of them is within a suitable range as an electronic component material.
Claims (9)
前記熱処理工程において前記水酸化ニッケル粒子を流動させながら該水酸化ニッケル粒子１ｇに対して５〜１５０ＮＬの範囲内において非還元性ガスの通気量を調整することによって該酸化ニッケル粉末の硫黄品位を５０質量ｐｐｍ以下に制御することを特徴とする酸化ニッケル微粉末の製造方法。 After neutralizing the nickel sulfate aqueous solution with alkali to generate nickel hydroxide particles containing sulfur and having a D90 of 5 to 60 μm measured by the laser scattering method, the sulfur grade of the nickel hydroxide particles is 1.0 to 0. The neutralization step of washing with water so as to be 3.0% by mass (excluding 1.0% by mass) and the nickel hydroxide particles obtained in the neutralization step exceed 850 ° C. in a non-reducing atmosphere. A method for producing fine nickel oxide powder, which comprises a heat treatment step of producing nickel oxide powder by heat treatment at a temperature of less than 1050 ° C.
50 sulfur grade nickel oxide powder by adjusting the aeration of the non-reducing gas in the range of 5 ～150NL with respect aqueous nickel oxide particles 1g in flowing the nickel hydroxide particles in the heat treatment step A method for producing fine nickel oxide powder, which comprises controlling the mass to ppm or less.
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