JP5170450B2 - Method for producing nickel powder - Google Patents
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- JP5170450B2 JP5170450B2 JP2009042540A JP2009042540A JP5170450B2 JP 5170450 B2 JP5170450 B2 JP 5170450B2 JP 2009042540 A JP2009042540 A JP 2009042540A JP 2009042540 A JP2009042540 A JP 2009042540A JP 5170450 B2 JP5170450 B2 JP 5170450B2
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- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 title claims description 160
- 238000004519 manufacturing process Methods 0.000 title claims description 37
- 239000000843 powder Substances 0.000 claims description 205
- BFDHFSHZJLFAMC-UHFFFAOYSA-L nickel(ii) hydroxide Chemical compound [OH-].[OH-].[Ni+2] BFDHFSHZJLFAMC-UHFFFAOYSA-L 0.000 claims description 122
- 239000002245 particle Substances 0.000 claims description 104
- 229910000480 nickel oxide Inorganic materials 0.000 claims description 76
- GNRSAWUEBMWBQH-UHFFFAOYSA-N oxonickel Chemical compound [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 claims description 76
- 230000009467 reduction Effects 0.000 claims description 62
- 239000007789 gas Substances 0.000 claims description 52
- 238000000034 method Methods 0.000 claims description 46
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 27
- 239000011777 magnesium Substances 0.000 claims description 23
- 239000001257 hydrogen Substances 0.000 claims description 21
- 229910052739 hydrogen Inorganic materials 0.000 claims description 21
- 230000008569 process Effects 0.000 claims description 20
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 14
- 150000001342 alkaline earth metals Chemical class 0.000 claims description 14
- 239000007864 aqueous solution Substances 0.000 claims description 9
- 150000002815 nickel Chemical class 0.000 claims description 7
- 230000003472 neutralizing effect Effects 0.000 claims description 4
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 3
- 229910052749 magnesium Inorganic materials 0.000 claims description 3
- 238000006722 reduction reaction Methods 0.000 description 62
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 20
- 230000000052 comparative effect Effects 0.000 description 19
- 238000005259 measurement Methods 0.000 description 19
- 229910052759 nickel Inorganic materials 0.000 description 16
- 230000003647 oxidation Effects 0.000 description 13
- 238000007254 oxidation reaction Methods 0.000 description 13
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 10
- 238000005245 sintering Methods 0.000 description 9
- 230000002776 aggregation Effects 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 8
- 230000001590 oxidative effect Effects 0.000 description 8
- 229910021586 Nickel(II) chloride Inorganic materials 0.000 description 7
- 238000004220 aggregation Methods 0.000 description 7
- 239000011362 coarse particle Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- QMMRZOWCJAIUJA-UHFFFAOYSA-L nickel dichloride Chemical compound Cl[Ni]Cl QMMRZOWCJAIUJA-UHFFFAOYSA-L 0.000 description 7
- 239000011230 binding agent Substances 0.000 description 6
- 229910001873 dinitrogen Inorganic materials 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 239000000919 ceramic Substances 0.000 description 5
- 238000009826 distribution Methods 0.000 description 5
- 238000002425 crystallisation Methods 0.000 description 4
- 230000006866 deterioration Effects 0.000 description 4
- 238000010304 firing Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 239000011261 inert gas Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000003153 chemical reaction reagent Substances 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 239000013067 intermediate product Substances 0.000 description 3
- 229910044991 metal oxide Inorganic materials 0.000 description 3
- 150000004706 metal oxides Chemical class 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 2
- 239000003985 ceramic capacitor Substances 0.000 description 2
- 238000011109 contamination Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229940050906 magnesium chloride hexahydrate Drugs 0.000 description 2
- DHRRIBDTHFBPNG-UHFFFAOYSA-L magnesium dichloride hexahydrate Chemical compound O.O.O.O.O.O.[Mg+2].[Cl-].[Cl-] DHRRIBDTHFBPNG-UHFFFAOYSA-L 0.000 description 2
- 229940091250 magnesium supplement Drugs 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- LAIZPRYFQUWUBN-UHFFFAOYSA-L nickel chloride hexahydrate Chemical compound O.O.O.O.O.O.[Cl-].[Cl-].[Ni+2] LAIZPRYFQUWUBN-UHFFFAOYSA-L 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 239000011164 primary particle Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 238000011946 reduction process Methods 0.000 description 2
- 239000003870 refractory metal Substances 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 239000012808 vapor phase Substances 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 239000001856 Ethyl cellulose Substances 0.000 description 1
- ZZSNKZQZMQGXPY-UHFFFAOYSA-N Ethyl cellulose Chemical compound CCOCC1OC(OC)C(OCC)C(OCC)C1OC1C(O)C(O)C(OC)C(CO)O1 ZZSNKZQZMQGXPY-UHFFFAOYSA-N 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- YZCKVEUIGOORGS-IGMARMGPSA-N Protium Chemical compound [1H] YZCKVEUIGOORGS-IGMARMGPSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 description 1
- 229910002113 barium titanate Inorganic materials 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 229920001249 ethyl cellulose Polymers 0.000 description 1
- 235000019325 ethyl cellulose Nutrition 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 238000004898 kneading Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 150000002816 nickel compounds Chemical class 0.000 description 1
- LGQLOGILCSXPEA-UHFFFAOYSA-L nickel sulfate Chemical compound [Ni+2].[O-]S([O-])(=O)=O LGQLOGILCSXPEA-UHFFFAOYSA-L 0.000 description 1
- 229910000363 nickel(II) sulfate Inorganic materials 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
Landscapes
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
- Powder Metallurgy (AREA)
Description
本発明は、ニッケル粉の製造方法に係り、より詳しくは積層セラミックコンデンサーの内部電極形成用として好適なニッケル粉の製造方法に関するものである。 The present invention relates to a method for producing nickel powder, and more particularly to a method for producing nickel powder suitable for forming an internal electrode of a multilayer ceramic capacitor.
積層セラミックコンデンサー（以下、ＭＬＣＣと称す）は、誘電体層と内部電極を交互に積層させた構造を有し、小型高容量の優れたコンデンサーである。そこに使用される誘電体層には、チタン酸バリウムに代表されるセラミックス系材料が用いられている。一方、内部電極には、従来貴金属系材料が用いられていたが、低コスト化の要求に伴い、近年ニッケル系材料が用いられてきている。 A multilayer ceramic capacitor (hereinafter referred to as MLCC) has a structure in which dielectric layers and internal electrodes are alternately stacked, and is an excellent capacitor having a small size and a high capacity. A ceramic material typified by barium titanate is used for the dielectric layer used there. On the other hand, a noble metal-based material has been conventionally used for the internal electrode, but in recent years, a nickel-based material has been used in accordance with a demand for cost reduction.
この内部電極にニッケル系材料であるニッケル粉を用いたＭＬＣＣは、以下のような製造工程によって作られている。
先ず、誘電体層となるグリーンシートに、ニッケル粉と有機溶剤を種々の添加剤とともに混練して作製したニッケルペーストを印刷し、乾燥させて内部電極を形成する。次いで、これを所望数積層し、熱圧着した後にチップ形状に切断する。切断後、３００℃程度の温度でグリーンシート及びニッケルペースト中のバインダーを除去する脱バインダー工程を施し、次に千数百度の温度で焼結し、外部電極を形成する。
The MLCC using nickel powder, which is a nickel-based material, for the internal electrode is manufactured by the following manufacturing process.
First, a nickel paste prepared by kneading nickel powder and an organic solvent together with various additives is printed on a green sheet serving as a dielectric layer, and dried to form an internal electrode. Next, the desired number of layers are stacked, and after thermocompression bonding, they are cut into chips. After cutting, a debinding step is performed to remove the binder in the green sheet and nickel paste at a temperature of about 300 ° C., and then sintering is performed at a temperature of several thousand degrees to form an external electrode.
この脱バインダー工程は、酸化雰囲気下の熱処理によりバインダーを燃焼させる方法が一般に行われている。バインダー材料としては、誘電体層を形成するグリーンシートでは、ポリビニルアルコール系の物質が用いられることが多く、内部電極形成用のニッケルペーストのバインダーにはエチルセルロース系の物質が用いられることが多い。これら両者の燃焼タイミング、発生ガス量を制御する形で、脱バインダー工程での雰囲気、温度が調整されている。 In this debinding process, a method of burning the binder by heat treatment under an oxidizing atmosphere is generally performed. As a binder material, a polyvinyl alcohol-based substance is often used for a green sheet forming a dielectric layer, and an ethyl cellulose-based substance is often used for a binder of a nickel paste for forming an internal electrode. The atmosphere and temperature in the debinding process are adjusted so as to control the combustion timing and the amount of generated gas.
使用するニッケル粉には、このＭＬＣＣの製造工程において意図しないガス発生を生じさせたり、酸化による顕著な体積変化が生じたりしないようにすることが求められ、その製造工程にて純度を厳密に制御され、表面状態が調整されている。また、誘電体層はセラミックであり、内部電極は金属であることから、一般的に、焼結時の収縮量は内部電極の方が大きく、一方、融点は金属の方が低いことから、焼結開始温度は内部電極の方が低い。したがって、ニッケルペーストにはセラミック粉末などを混合して焼結現象を遅延させたり、また、ニッケル粉そのものに他の元素を微量に添加したりすることで同効果を得ることがなされている。 The nickel powder to be used is required not to cause unintentional gas generation in the MLCC manufacturing process or to cause a significant volume change due to oxidation. The purity is strictly controlled in the manufacturing process. The surface condition is adjusted. In addition, since the dielectric layer is ceramic and the internal electrode is a metal, generally the shrinkage during sintering is larger for the internal electrode, while the melting point is lower for the metal. The starting temperature of the internal electrode is lower. Therefore, the same effect can be obtained by mixing ceramic powder or the like in the nickel paste to delay the sintering phenomenon, or adding a small amount of other elements to the nickel powder itself.
このような製造工程でＭＬＣＣは製造されているが、近年要求されるＭＬＣＣの更なる小型化、高容量化により、内部電極および誘電体層の厚みの薄層化、高積層化が進められている。
薄層化された内部電極では、ニッケル粉の粒径が大きいと電極厚み方向に存在する粒子数が少なく、また、粒子間の空隙も大きくなることから、焼結後の電極に穴開きや途切れが発生して電極として機能しなくなる。このため、内部電極に用いられるニッケル粉においてもさらに微細な粒径のものが求められている。また、薄層化されたＭＬＣＣにおいては、粗大なニッケル粉が混入していると電極間のショートが発生するため、粗大粒子が含まれないことも要求されている。さらに、平均粒径より大幅に細かい粒子が存在すると脱バインダー工程での酸化、焼結工程での焼結開始温度の低温化が生じるため、極端に粒径の細かい粒子も含まれないことも重要である。
Although MLCCs are manufactured in such a manufacturing process, the internal electrodes and dielectric layers have been made thinner and higher in number due to further miniaturization and higher capacity of MLCCs required in recent years. Yes.
In the thinned internal electrode, if the particle size of the nickel powder is large, the number of particles existing in the electrode thickness direction is small, and the voids between the particles are also large. Occurs and does not function as an electrode. For this reason, the nickel powder used for the internal electrode is also required to have a finer particle size. In addition, in the MLCC having a thin layer, when coarse nickel powder is mixed, a short circuit between the electrodes occurs, and it is also required that coarse particles are not included. In addition, if there are particles that are significantly finer than the average particle size, oxidation in the binder removal process and lowering of the sintering start temperature in the sintering process occur, so it is also important that particles with extremely small particle diameters are not included. It is.
以上のように、内部電極用のニッケル粉に対しては、脱バインダー工程でガスを発生し難いこと、誘電体の焼結収縮特性に近いことなども求められているが、微細で均一な粒径であることが最も重要な要求特性となっている。 As described above, nickel powder for internal electrodes is also required to be less likely to generate gas in the binder removal process and close to the sintering shrinkage characteristics of the dielectric. The diameter is the most important required characteristic.
上記問題を解決するため、種々の方法で製造された微細で粗大粒子を含まないニッケル粉が提案されている。
例えば、特許文献１では、塩化ニッケル蒸気の気相水素還元法による平均粒径が０．２〜０．６μｍであり、かつ平均粒径の２．５倍以上の粒径をもつ粗粒子の存在率が個数基準で０．１％以下としたニッケル粉が提案されている。
In order to solve the above problems, nickel powders produced by various methods and containing no coarse particles have been proposed.
For example, in Patent Document 1, the presence of coarse particles having an average particle size of 0.2 to 0.6 μm by vapor phase hydrogen reduction of nickel chloride vapor and having a particle size of 2.5 times or more the average particle size Nickel powder with a rate of 0.1% or less on the number basis has been proposed.
また、特許文献２においては、平均粒径が０．１〜１．０μｍのニッケル粉であって、粒径２μｍ以上のニッケル粉の含有率が個数基準で７００／１００万以下であるニッケル粉が、塩化ニッケル蒸気の気相水素還元法等で得たニッケル粉を液体サイクロン等で分級することで得られることが開示されている。 Moreover, in patent document 2, it is nickel powder with an average particle diameter of 0.1-1.0 micrometer, Comprising: The nickel powder whose content rate of nickel powder with a particle diameter of 2 micrometers or more is 700/1 million or less on a number basis. It is disclosed that nickel powder obtained by vapor phase hydrogen reduction of nickel chloride vapor can be obtained by classification with a liquid cyclone or the like.
さらに、特許文献３においては、レーザ回折散乱式粒度分布測定による平均粒径の１．５倍以上の粒子径を持つ粒子個数が全粒子個数の２０％以下であり、平均粒子径の０．５倍以下の粒子径を持つ粒子個数が全粒子個数の５％以下であり、ＳＥＭ観察による平均一次粒子径が０．１〜２μｍであるニッケル粉が提案されている。このニッケル粉は、ニッケル塩を原料として水溶液中で還元処理する湿式法等により得られた凝集体を含むニッケル粉を原粉として用いて解粒処理によって得られるものである。 Further, in Patent Document 3, the number of particles having a particle size of 1.5 times or more of the average particle size measured by laser diffraction scattering type particle size distribution measurement is 20% or less of the total particle number, and the average particle size is 0.5%. Nickel powder has been proposed in which the number of particles having a particle size of twice or less is 5% or less of the total number of particles, and the average primary particle size by SEM observation is 0.1 to 2 μm. This nickel powder is obtained by a pulverization treatment using a nickel powder containing an aggregate obtained by a wet process in which a nickel salt is used as a raw material in an aqueous solution and the like as a raw powder.
一方、低コストが期待されるニッケル粉としては、水酸化ニッケルの加熱還元によって得られるニッケル粉が挙げられる。例えば、特許文献４には、反応槽内のスラリーに、含ニッケル溶液を連続的に添加しつつ、アルカリ溶液を添加して水酸化ニッケルを生成させ、該スラリーを濾過し、水洗し、乾燥して水酸化ニッケルを得、これを還元剤として水素を用い、還元温度を４００〜５５０℃として加熱還元することによりニッケル粉を得る製造方法が開示されている。 On the other hand, nickel powder that is expected to be low in cost includes nickel powder obtained by heat reduction of nickel hydroxide. For example, in Patent Document 4, while adding a nickel-containing solution continuously to a slurry in a reaction vessel, an alkaline solution is added to form nickel hydroxide, and the slurry is filtered, washed with water, and dried. Thus, there is disclosed a production method for obtaining nickel powder by obtaining nickel hydroxide, using hydrogen as a reducing agent, and heating and reducing at a reduction temperature of 400 to 550 ° C.
また、均一な金属粉またはセラミック粉の製造方法に、原料を垂直炉中を落下させながら焼成あるいは還元する方法が提案されている。
例えば、特許文献５には、垂直管形炉を反応容器として用い、耐熱金属酸化物または弁金属酸化物を連続的供給物として供給し、反応容器中で還元し、連続的還元反応により粉末を製造する方法が提案され、具体例として、垂直管形炉上部から耐熱金属酸化物粉末を供給し、反応物質を流動させ、炉下部で還元生成物を回収することが開示されている。また、垂直に設置された炉チューブと、被焼成材料を前記炉チューブ内に落下させる投入装置と、前記炉チューブの下端部に加熱保持する加熱炉を有する垂直焼成炉を用い、炉内の雰囲気ガスの流量調整によって焼成時間を調整する焼成方法も特許文献６に提案されている。
Further, as a method for producing uniform metal powder or ceramic powder, a method of firing or reducing raw materials while dropping in a vertical furnace has been proposed.
For example, in Patent Document 5, a vertical tube furnace is used as a reaction vessel, refractory metal oxide or valve metal oxide is supplied as a continuous feed, reduced in the reaction vessel, and powder is obtained by continuous reduction reaction. A manufacturing method has been proposed. As a specific example, it is disclosed that refractory metal oxide powder is supplied from the upper part of a vertical tube furnace, the reactants are flowed, and the reduction product is recovered at the lower part of the furnace. Also, using a vertical firing furnace having a vertically installed furnace tube, a charging device for dropping the material to be fired into the furnace tube, and a heating furnace heated and held at the lower end of the furnace tube, the atmosphere in the furnace Patent Document 6 also proposes a firing method in which the firing time is adjusted by adjusting the gas flow rate.
しかしながら、特許文献１から特許文献３に提案されているニッケル粉は、いずれもコストが高くなるという問題がある。即ち、気相水素還元法で得られるニッケル粉は結晶性もよく特性面で優れているが生産性が低く、この気相水素還元法で得たニッケル粉の粒径を均一にしようとして分級することは、その歩留を悪化させることに他ならず、より高コストとなってしまう。
また、湿式法により得られた凝集体を解粒処理しても、解粒前の一次粒子径が均一でなければ分級する必要があり、歩留悪化による高コスト化は避けられない。湿式法では粒子径が比較的均一なニッケル粉が得られるが、生産性は低く、コスト高となる問題も解決されない。
However, all of the nickel powders proposed in Patent Document 1 to Patent Document 3 have a problem of high cost. That is, the nickel powder obtained by the gas phase hydrogen reduction method has good crystallinity and excellent characteristics, but the productivity is low, and the nickel powder obtained by the gas phase hydrogen reduction method is classified in order to make the particle size uniform. That is nothing but worsening the yield, and the cost becomes higher.
Moreover, even if the agglomerates obtained by the wet method are pulverized, if the primary particle diameter before pulverization is not uniform, it is necessary to classify, and an increase in cost due to yield deterioration is inevitable. In the wet method, nickel powder having a relatively uniform particle size can be obtained, but the productivity is low and the problem of high cost cannot be solved.
一方、特許文献４に提案される水酸化ニッケルの加熱還元によって得られるニッケル粉は、その大量生産が可能で低コストであるが、微細で均一な粒径のニッケル粉が得難いという問題点がある。 On the other hand, the nickel powder obtained by heat reduction of nickel hydroxide proposed in Patent Document 4 can be mass-produced and is low-cost, but there is a problem that it is difficult to obtain nickel powder having a fine and uniform particle size. .
また、原料を垂直炉中を落下させながら焼成あるいは還元する特許文献５、６で提案されている製造方法では、原料からの金属粉またはセラミック粉の製造を垂直炉による工程のみで行っているため、ニッケル粉の製造のような中間生成物を介して、その中間生成物をさらに還元する製造方法においては、その中間生成物の特性が最終的に得られる粉末の特性に影響を及ぼすために、特許文献５、６で提案されるような製造方法の適用が可能であるか不明である。 Further, in the manufacturing methods proposed in Patent Documents 5 and 6 in which the raw material is fired or reduced while being dropped in a vertical furnace, metal powder or ceramic powder from the raw material is manufactured only by the process using the vertical furnace. In a production method in which the intermediate product is further reduced through an intermediate product such as the production of nickel powder, since the properties of the intermediate product affect the properties of the finally obtained powder, It is unclear whether the manufacturing method proposed in Patent Documents 5 and 6 can be applied.
このように微細で均一な粒径のニッケル粉を大量に低コストで製造する方法は、未だ開発されていないのが実状であり、このような状況を鑑み本発明はなされたもので、微細で均一な粒径を持ったニッケル粉を大量に高効率で製造が可能な低コストなニッケル粉の製造方法の提供を目的とするものである。 Thus, a method for producing a large amount of nickel powder having a uniform and uniform particle size at a low cost in large quantities has not been developed yet, and the present invention has been made in view of such a situation. An object of the present invention is to provide a low-cost nickel powder production method capable of producing a large amount of nickel powder having a uniform particle size with high efficiency.
本発明者らは、従来のニッケル粉における問題点を解決するため、水酸化ニッケルを焙焼処理し、次いで加熱還元を施すことによりニッケル粉を得る方法について鋭意研究を進め、雰囲気ガス中に分散させて水酸化ニッケル粉の焙焼処理を行うことで酸化ニッケル粉を得ること、焙焼処理中の雰囲気ガスの影響が最終的に得られるニッケル粉の特性に大きな影響を及ぼすこと、さらに、得られた酸化ニッケル粉を特定条件で加熱還元することにより、微細で均一な粒径のニッケル粉が高効率で得られることの知見を得て、本発明の完成に至ったものである。 In order to solve the problems in conventional nickel powders, the present inventors have conducted earnest research on a method of obtaining nickel powder by roasting nickel hydroxide and then subjecting it to heat reduction, and dispersed in atmospheric gas. The nickel hydroxide powder is roasted to obtain nickel oxide powder, and the influence of the atmospheric gas during the roasting process has a great influence on the properties of the nickel powder finally obtained. The inventors have obtained the knowledge that a nickel powder having a fine and uniform particle size can be obtained with high efficiency by heating and reducing the obtained nickel oxide powder under specific conditions, and the present invention has been completed.
すなわち、本発明の第１の発明は、アルカリ土類金属を含む水酸化ニッケル粉を焙焼処理して酸化ニッケル粉とし、得られた酸化ニッケル粉を還元処理してニッケル粉とするニッケル粉の製造方法において、
工程Ａ：ニッケル塩を含む水溶液を中和晶析してアルカリ土類金属を０．００２〜１質量％含む水酸化ニッケル粉の形成工程、
工程Ｂ：工程Ａで形成した水酸化ニッケル粉から平均粒径１〜１００μｍの水酸化ニッケル粉群を構成し、この水酸化ニッケル粉群を非還元性ガス中に上方から落下させ、２．１ｇ／ｃｍ２・ｓｅｃ以下の装入量により３００〜１０００℃の該非還元性ガス中に分散せしめた状態で酸化ニッケル粉へと焙焼処理すると共に、前記非還元性ガスおよび前記酸化ニッケル粉の焙焼処理により生じる水蒸気を水酸化ニッケル粉１ｇに対して排気温度０〜５０℃の状態で０．２リットル／分以上の速度で排気する水酸化ニッケル粉の酸化ニッケル粉への焙焼工程、
工程Ｃ：工程Ｂで作製した酸化ニッケル粉を３００〜５００℃の温度で還元してニッケル粉を得る還元工程、
を含むニッケル粉の製造方法である。
That is, according to the first aspect of the present invention, nickel hydroxide powder containing an alkaline earth metal is roasted to obtain nickel oxide powder, and the obtained nickel oxide powder is reduced to nickel powder. In the manufacturing method,
Step A: Step of forming nickel hydroxide powder containing 0.002 to 1% by mass of alkaline earth metal by neutralizing and crystallization of an aqueous solution containing nickel salt,
Step B: A nickel hydroxide powder group having an average particle diameter of 1 to 100 μm is formed from the nickel hydroxide powder formed in Step A, and this nickel hydroxide powder group is dropped into the non-reducing gas from above, 2.1 g / cm while roasting and by 2 · sec or less in charging amount to 300 to 1000 ° C. of the non-reducing gas nickel oxide powder in a state of dispersed in, the non-reducing gas and the nickel oxide powder A process of roasting nickel hydroxide powder into nickel oxide powder that exhausts water vapor generated by the roasting treatment at a rate of 0.2 liters / minute or more at an exhaust temperature of 0 to 50 ° C. with respect to 1 g of nickel hydroxide powder;
Step C: A reduction step of reducing the nickel oxide powder produced in Step B at a temperature of 300 to 500 ° C. to obtain nickel powder,
It is a manufacturing method of the nickel powder containing this.
本発明の第２の発明は、第１の発明における工程Ｂの水酸化ニッケル粉を３００〜１０００℃の非還元性ガス中における保持時間が、３〜１０秒間であるニッケル粉の製造方法である。 The second aspect of the present invention, the retention time of nickel hydroxide powder from Step B of those of the first inventions in the non-reducing gas 300 to 1000 ° C. The method for producing a nickel powder is 3 to 10 seconds It is.
本発明の第３の発明は、第１の発明または第２の発明における工程Ｂの非還元性ガスが、空気であるニッケル粉の製造方法である。 3rd invention of this invention is a manufacturing method of the nickel powder whose nonreducing gas of the process B in 1st invention or 2nd invention is air.
本発明の第４の発明は、第１の発明から第３の発明のいずれかにおける工程Ｂの水酸化ニッケル粉の酸化ニッケル粉への焙焼工程が、大気圧下で行われるニッケル粉の製造方法である。 The fourth invention of the present invention is the production of nickel powder, wherein the roasting step of the nickel hydroxide powder of step B in any one of the first to third inventions to nickel oxide powder is performed under atmospheric pressure. Is the method.
本発明の第５の発明は、第１の発明から第４の発明のいずれかにおける工程Ｃの酸化ニッケル粉の還元処理が、酸化ニッケル粉１ｇに対して０．０１〜０．２リットル／分の水素流量における水素濃度を示す水素雰囲気下で行われるニッケル粉の製造方法である。 According to a fifth aspect of the present invention, the reduction treatment of the nickel oxide powder in the step C in any one of the first to fourth aspects is performed at 0.01 to 0.2 liter / min with respect to 1 g of the nickel oxide powder. It is the manufacturing method of the nickel powder performed in the hydrogen atmosphere which shows the hydrogen concentration in the hydrogen flow rate.
本発明の第６の発明は、アルカリ土類金属が、マグネシウムである第１の発明から第５の発明のいずれかに記載のニッケル粉の製造方法である。 A sixth invention of the present invention is the nickel powder manufacturing method according to any one of the first to fifth inventions, wherein the alkaline earth metal is magnesium.
本発明の第７の発明は、ニッケル粉の平均粒径が、０．２〜０．５μｍである第１の発明から第６の発明のいずれかに記載のニッケル粉の製造方法である。 Seventh aspect of the present invention has an average particle size of the nickel powder, a method for producing a nickel powder according to any one of the sixth aspect of the first invention is 0.2 to 0.5 [mu] m.
本発明は、水酸化ニッケル粉を酸化焙焼して酸化ニッケル粉を形成した後、この酸化ニッケル粉を加熱還元することで、微細で均一な粒径のニッケル粉を大量に高効率で製造することができるという優れた効果を有するものである。 In the present invention, after nickel hydroxide powder is oxidized and roasted to form nickel oxide powder, the nickel oxide powder is heated and reduced to produce a large amount of nickel powder having a fine and uniform particle size with high efficiency. Ru der having an excellent effect that it is possible.
特に、焙焼時間を短縮して大幅に効率を向上させることにより低コスト化を実現することが可能であり、本発明により得られるニッケル粉は、特に小型化、高容量化が進むＭＬＣＣ内部電極形成用として好適なものであり、極めて大きな工業的価値を奏するものである。 In particular, by greatly improve efficiency by reducing the roasting time it is possible to realize cost reduction, the nickel powder obtained by the present invention, MLCC internal particularly compact, high capacity proceeds It is suitable for forming an electrode and exhibits extremely great industrial value.
本発明の製造方法は、アルカリ土類金属を含む水酸化ニッケル粉を焙焼して酸化ニッケル粉を作製し、この酸化ニッケル粉を還元することでニッケル粉を形成するニッケル粉の製造方法において、工程Ａ：ニッケル塩を含む水溶液を中和晶析してアルカリ土類金属を０．００２〜１質量％含む水酸化ニッケル粉の形成工程と、工程Ｂ：工程Ａで得られた水酸化ニッケル粉から平均粒径１〜１００μｍの水酸化ニッケル粉群を構成し、この水酸化ニッケル粉群を３００〜１０００℃の非還元性ガス中に、２．１ｇ／ｃｍ２・ｓｅｃ以下の装入量により分散せしめた状態で酸化ニッケル粉に焙焼処理すると共に、非還元性ガスおよび酸化ニッケル粉の生成により生じる水蒸気を水酸化ニッケル粉１ｇに対して排気温度０〜５０℃の状態で０．２リットル／分以上の速度で排気する水酸化ニッケル粉の酸化ニッケル粉への焙焼工程と、工程Ｃ：得られた酸化ニッケル粉を３００〜５００℃の温度で還元処理してニッケル粉を得る還元工程を含む製造方法である。 In the manufacturing method of the present invention, the nickel hydroxide powder containing alkaline earth metal is roasted to produce nickel oxide powder, and the nickel oxide powder is reduced to form nickel powder. Step A: Neutral crystallization of aqueous solution containing nickel salt to form nickel hydroxide powder containing 0.002 to 1% by mass of alkaline earth metal; Step B: Nickel hydroxide powder obtained in step A Is composed of a nickel hydroxide powder group having an average particle diameter of 1 to 100 μm, and the nickel hydroxide powder group is charged in a non-reducing gas at 300 to 1000 ° C. with a charging amount of 2.1 g / cm 2 · sec or less. The nickel oxide powder is roasted in the dispersed state, and the water vapor generated by the generation of the non-reducing gas and the nickel oxide powder is reduced by 0.2 liters at an exhaust temperature of 0 to 50 ° C. with respect to 1 g of the nickel hydroxide powder. Roasting step of nickel hydroxide powder exhausted at a rate of at least torr / min to nickel oxide powder, and step C: reduction to obtain nickel powder by reducing the obtained nickel oxide powder at a temperature of 300 to 500 ° C. It is a manufacturing method including a process.
即ち、本発明における要点は、水酸化ニッケル粉を雰囲気ガス中で分散状態にし、特定の焙焼条件における酸化ニッケル粉への焙焼処理を行うことにある。
一般に、ニッケル化合物を還元処理してニッケル粉を得る場合、生産性や不純物等の混入を考慮して、中和晶析法等の湿式法で得られた水酸化ニッケル粉を酸化焙焼して、酸化ニッケル粉とし還元処理する方法が用いられる。ここで、酸化ニッケル粉を経由してニッケル粉とするのは、水酸化ニッケル粉を直接還元すると水酸化ニッケル粉から多量に発生する水蒸気が、ニッケル粉の凝集を促進し、得られるニッケル粉の分散性の劣化を防止するためである。したがって、還元処理する酸化ニッケル粉は、十分に酸化焙焼され残留する水酸化ニッケル粉が含まれる量を可能な限り低減することが必要である。
That is, the main point in the present invention is that nickel hydroxide powder is dispersed in an atmospheric gas, and is subjected to roasting treatment to nickel oxide powder under specific roasting conditions.
Generally, when nickel powder is obtained by reduction treatment of nickel compound, nickel hydroxide powder obtained by wet method such as neutralization crystallization method is oxidized and roasted in consideration of productivity and contamination of impurities. A method of reducing nickel oxide powder is used. Here, the nickel powder is converted into nickel powder via nickel oxide powder. When nickel hydroxide powder is directly reduced, water vapor generated in a large amount from nickel hydroxide powder promotes the aggregation of nickel powder, and the resulting nickel powder This is to prevent deterioration of dispersibility. Therefore, it is necessary for the nickel oxide powder to be reduced to reduce as much as possible the amount of nickel hydroxide powder that is sufficiently oxidized and roasted and remains.
この水酸化ニッケル粉の酸化焙焼の焙焼処理は、通常、静置した水酸化ニッケル粉を非還元雰囲気中で過熱する静置方式により行われる。しかしながら、静置した状態で水酸化ニッケル粉を酸化焙焼すると、内部で発生した水蒸気が系外に完全に排出さず、水酸化ニッケル粉が残存する可能性が高く、このような状態を防止するためには、流動床方式等により酸化焙焼することが考えられるが、焙焼処理により生成した酸化ニッケル粉と未焙焼の水酸化ニッケル粉が混在するため、水酸化ニッケル粉が残留する可能性が残る。 This roasting treatment for the oxidation roasting of nickel hydroxide powder is usually performed by a standing method in which the standing nickel hydroxide powder is heated in a non-reducing atmosphere. However, if nickel hydroxide powder is oxidized and roasted in a stationary state, the water vapor generated inside is not completely discharged out of the system, and there is a high possibility that nickel hydroxide powder remains, preventing such a state. In order to do this, it is conceivable to oxidize and roast using a fluidized bed method or the like, but nickel hydroxide powder produced by roasting treatment and unroasted nickel hydroxide powder are mixed, so that nickel hydroxide powder remains. The possibility remains.
また、静置方式により酸化焙焼する場合、焙焼時間を長くする、あるいは高温化することが考えられるが、いずれの場合も十分な対策とは言えない。すなわち、焙焼時間を長くしても必ずしも内部まで十分に酸化ニッケル粉に転換されないばかりか、酸化ニッケル粉の凝集、生産性の低下によるコスト増などの問題が生じる。さらに、酸化焙焼温度を高温化すると、酸化ニッケル粉の凝集・粒成長が起こる。この酸化ニッケル粉の凝集・粒成長が起こると、還元して得られるニッケル粉の分散性が悪化するため、酸化ニッケル粉の粉体特性および形状を適度な状態に維持することも重要な要素となる。 In addition, in the case of oxidative roasting by a stationary method, it is conceivable that the roasting time is lengthened or the temperature is raised, but neither case is a sufficient measure. That is, even if the roasting time is lengthened, not only the inside is not sufficiently converted into nickel oxide powder, but also problems such as aggregation of nickel oxide powder and increased cost due to a decrease in productivity arise. Furthermore, when the oxidation roasting temperature is increased, the nickel oxide powder aggregates and grows. When the aggregation and grain growth of this nickel oxide powder occur, the dispersibility of the nickel powder obtained by reduction deteriorates, so maintaining the powder characteristics and shape of the nickel oxide powder in an appropriate state is also an important factor. Become.
そこで、本発明では雰囲気ガス中に水酸化ニッケル粉を分散した状態で酸化焙焼することにより、これらの問題が解決され、以降の還元工程により良好なニッケル粉となる酸化ニッケル粉が得られるものである。
この水酸化ニッケル粉を雰囲気ガス中に分散した状態にすることは、水酸化ニッケル粉の酸化ニッケル粉への転換時に発生する水蒸気を系外に排出する作用を生み、従って水酸化ニッケル粉を十分に、実質的に全てを酸化ニッケル粉に転換することができる。また、酸化ニッケル粉の凝集も防止することができる。
Accordingly, in the present invention, these problems are solved by oxidizing and roasting in a state in which nickel hydroxide powder is dispersed in an atmospheric gas, and nickel oxide powder that becomes good nickel powder is obtained by the subsequent reduction process. It is.
Dispersing the nickel hydroxide powder in the atmosphere gas has the effect of discharging the water vapor generated during the conversion of the nickel hydroxide powder into nickel oxide powder out of the system, and therefore the nickel hydroxide powder is sufficient. In addition, substantially all can be converted to nickel oxide powder. Moreover, aggregation of nickel oxide powder can also be prevented.
雰囲気ガス中に水酸化ニッケル粉が分散した状態で酸化焙焼する方法としては、焙焼領域に、雰囲気ガスとともに水酸化ニッケル粉を噴出し、酸化焙焼して落下する酸化ニッケル粉を回収する方法が考えられるが、この方法ではノズル等を用いて水酸化ニッケル粉を噴出させ、高温域を通過させて酸化焙焼した後、回収する方法であるために、装置が複雑になる上、多量に雰囲気ガスが必要になるなどの問題がある。
そこで、装置の簡易性、酸化ニッケル粉への未焙焼の水酸化ニッケル粉の混入防止を考慮すると、水酸化ニッケル粉を雰囲気ガス中に上方から落下させることにより分散させる方法が好ましい。
As a method of oxidizing and roasting in a state where nickel hydroxide powder is dispersed in the atmosphere gas, nickel hydroxide powder is jetted together with the atmosphere gas into the roasting region, and nickel oxide powder falling by oxidation roasting is recovered. A method is conceivable, but this method involves jetting nickel hydroxide powder using a nozzle, etc., passing it through a high temperature region, and then recovering it after oxidation. There are problems such as the need for atmospheric gas.
In view of the simplicity of the apparatus and the prevention of mixing of unbaked nickel hydroxide powder into the nickel oxide powder, a method of dispersing the nickel hydroxide powder by dropping it into the atmosphere gas from the upper side is preferable.
すなわち、焙焼温度まで加熱した焙焼領域の上方から水酸化ニッケル粉を落下させ、焙焼領域を通過させて焙焼処理した後、下部で回収する方法である。例えば、焙焼温度まで加熱した炉の上部から水酸化ニッケル粉を炉内に満たされた雰囲気ガス（本発明では非還元性ガス）中で分散するように投入、落下させ、炉の下部で回収することで水酸化ニッケル粉を酸化焙焼して酸化ニッケル粉を得る方法である。 That is, the nickel hydroxide powder is dropped from above the roasting area heated to the roasting temperature, passed through the roasting area and roasted, and then recovered at the lower part. For example, nickel hydroxide powder is thrown from the top of the furnace heated to the roasting temperature so as to be dispersed in the atmosphere gas filled in the furnace (in the present invention, non-reducing gas), dropped, and recovered at the bottom of the furnace This is a method for obtaining nickel oxide powder by oxidizing and baking nickel hydroxide powder.
この場合、水酸化ニッケル粉が雰囲気ガス中に効率良く分散するような投入方法を採用すると良い。一例として、炉の投入口に水酸化ニッケル粉の粒径よりは、やや大きめのメッシュを持つ篩を設置し、この篩を加振しながら水酸化ニッケル粉を炉内に投入する方法、或いは雰囲気ガスを炉内で螺旋流となるように流すことで投入される水酸化ニッケル粉を分散せしめる方法などを用いることができるが、本発明ではこれらの方法には拘束されることはなく、水酸化ニッケル粉を分散状態で焙焼領域を通過できる方法であるならどのような方法であっても良い。 In this case, it is preferable to adopt a charging method in which nickel hydroxide powder is efficiently dispersed in the atmospheric gas. As an example, a method in which a sieve having a slightly larger mesh than the particle size of nickel hydroxide powder is installed at the furnace inlet, and nickel hydroxide powder is introduced into the furnace while vibrating this sieve, or atmosphere Although it is possible to use a method of dispersing nickel hydroxide powder introduced by flowing a gas in a spiral flow in a furnace, the present invention is not restricted by these methods. Any method may be used as long as the nickel powder can be passed through the roasting region in a dispersed state.
本発明において、非還元性ガス中で水酸化ニッケル粉を分散状態とするには、非還元性ガス中への水酸化ニッケル粉の装入量を、２．１ｇ／ｃｍ２・ｓｅｃ以下の範囲とする。この水酸化ニッケル粉の装入量が多い場合には、水酸化ニッケル粉は非還元性ガス中で塊となりやすく、望む分散状態を形成することが困難となる。装入量が少ない場合には、分散状態を作り易いが、酸化ニッケル粉の生成効率が悪くなるため、０．１ｇ／ｃｍ２・ｓｅｃ以上とすることが好ましい。 In the present invention, in order to make the nickel hydroxide powder dispersed in the non-reducing gas, the amount of the nickel hydroxide powder charged into the non-reducing gas is within a range of 2.1 g / cm 2 · sec or less. And When the amount of the nickel hydroxide powder is large, the nickel hydroxide powder tends to be agglomerated in the non-reducing gas and it is difficult to form a desired dispersion state. When the charging amount is small, it is easy to make a dispersed state, but since the production efficiency of nickel oxide powder is deteriorated, it is preferably 0.1 g / cm 2 · sec or more.
焙焼処理に用いる炉としては、上方から下方に水酸化ニッケル粉を通過させることが可能であれば特に限定されるものでなく、温度制御および転換後の酸化ニッケル粉の回収が容易なことから、炉芯を垂直方向に設置した管状炉（垂直型管状炉）を用いることが好ましい。また、この管状炉の断面形状は、特に限定されるものではなく、落下時に水酸化ニッケル粉が炉壁に付着しない断面積を有すればよい。 The furnace used for the roasting treatment is not particularly limited as long as the nickel hydroxide powder can be passed from the upper side to the lower side, and it is easy to control the temperature and recover the nickel oxide powder after the conversion. It is preferable to use a tubular furnace (vertical tubular furnace) in which the furnace core is installed in the vertical direction. In addition, the cross-sectional shape of the tubular furnace is not particularly limited as long as it has a cross-sectional area in which nickel hydroxide powder does not adhere to the furnace wall when dropped.
水酸化ニッケル粉を分散させる雰囲気ガスは、非還元性ガスであれば、酸化性ガス、不活性ガスのいずれでもよいが、酸化ニッケル粉への転換を十分に行うためには、酸化性ガスが好ましく、コスト面を考慮すると空気を用いることが好ましい。 The atmosphere gas for dispersing the nickel hydroxide powder may be either an oxidizing gas or an inert gas as long as it is a non-reducing gas. However, in order to sufficiently convert to nickel oxide powder, an oxidizing gas is used. Preferably, air is preferably used in consideration of cost.
次に、十分に水酸化ニッケル粉を酸化ニッケル粉へと転換させるには、発生する水蒸気を系外に排出する必要がある。このため、系内から非還元性ガスおよび酸化ニッケル粉の形成に伴い生成した水蒸気を、その合計で水酸化ニッケル粉１ｇに対して０．２リットル／分以上の排気速度で排気を行う。この速度以上で排気することで、非還元性ガスと共に発生した水蒸気を系外に排出することができ、水酸化ニッケル粉は十分に酸化ニッケル粉へ転換される。 Next, in order to sufficiently convert the nickel hydroxide powder into nickel oxide powder, it is necessary to discharge the generated water vapor out of the system. For this reason, the water vapor | steam produced | generated with the formation of non-reducing gas and nickel oxide powder from the inside of the system is exhausted at a pumping speed of 0.2 liter / min or more with respect to 1 g of nickel hydroxide powder in total. By exhausting at this speed or higher, water vapor generated together with the non-reducing gas can be discharged out of the system, and the nickel hydroxide powder is sufficiently converted to nickel oxide powder.
この排気速度は、水酸化ニッケル粉１ｇに対して排気温度０〜５０℃の状態で０．２から２リットル／分とすることが好ましい。排気速度が水酸化ニッケル粉１ｇに対して０．２リットル／分未満では、系内に存在する水蒸気が多くなり、十分に酸化ニッケル粉に転換することができない。一方、排気する速度を速くすることで、均一微細なニッケル粉を得る効果は得られるが、過度に速くしてもその効果に更なる改善はなく、コスト増となるのみであるばかりか、微細な酸化ニッケル粉が系外に飛散して歩留も低下することがある。このため、用いる炉の形状、大きさによるが、排気速度は水酸化ニッケル粉１ｇに対して２リットル／分以下とすることが好ましい。 The exhaust speed is preferably 0.2 to 2 liters / minute in an exhaust temperature of 0 to 50 ° C. with respect to 1 g of nickel hydroxide powder. If the exhaust speed is less than 0.2 liter / min with respect to 1 g of nickel hydroxide powder, the amount of water vapor present in the system increases and cannot be sufficiently converted to nickel oxide powder. On the other hand, by increasing the exhaust speed, the effect of obtaining uniform fine nickel powder can be obtained, but even if it is excessively fast, there is no further improvement in the effect, which not only increases the cost but also increases the fineness. Nickel oxide powder may be scattered outside the system and yield may be reduced. For this reason, although depending on the shape and size of the furnace to be used, the exhaust speed is preferably 2 liters / minute or less with respect to 1 g of nickel hydroxide powder.
また、系内から排気を行うと減圧雰囲気となるため、非還元性ガスを系内に吸気させることで系内の圧力を大気圧に調整しても良い。このとき、酸化ニッケル粉が効率よく得られるように、圧力を加圧もしくは減圧して調整することもできる。非還元性ガスとして空気を用い、かつ大気圧に調整する場合は、吸気口を大気に開放することで容易な調整を可能とする。 Further, since exhausting from the system creates a reduced pressure atmosphere, the pressure in the system may be adjusted to atmospheric pressure by sucking non-reducing gas into the system. At this time, the pressure can be adjusted by increasing or decreasing the pressure so that the nickel oxide powder can be obtained efficiently. When air is used as the non-reducing gas and the pressure is adjusted to atmospheric pressure, easy adjustment is possible by opening the air inlet to the atmosphere.
以下、工程ごとに詳細に説明する。
［工程Ａ］
工程Ａは、ニッケル塩を含む水溶液を中和晶析してアルカリ土類金属を０．００２〜１質量％含む水酸化ニッケル粉の形成工程である。
本発明に係るニッケル粉の製造方法において用いられる水酸化ニッケル粉は、通常の公知の方法により得ることができる。例えば、塩化ニッケルや硫酸ニッケルなどの水溶性ニッケル塩の水溶液をｐＨ制御して中和沈殿させることで得られる水酸化ニッケル粉を用いることができる。水酸化ニッケル粉に含有されるアルカリ土類金属は、水溶性塩などの水溶性物質としてニッケル塩水溶液に混合しておき、水酸化ニッケル粉の生成時に共沈させてやればよい。水酸化ニッケル粉を製造する反応設備に特に制限はなく、通常用いられる設備でよく、例えば、攪拌機を有する貯槽でｐＨ管理が行なえるものであればよい。
Hereinafter, each process will be described in detail.
[Step A]
Step A is a step of forming nickel hydroxide powder containing 0.002 to 1% by mass of an alkaline earth metal by neutralizing and crystallization of an aqueous solution containing a nickel salt.
The nickel hydroxide powder used in the method for producing nickel powder according to the present invention can be obtained by an ordinary known method. For example, nickel hydroxide powder obtained by neutralizing and precipitating an aqueous solution of a water-soluble nickel salt such as nickel chloride or nickel sulfate by pH control can be used. The alkaline earth metal contained in the nickel hydroxide powder may be mixed with a nickel salt aqueous solution as a water-soluble substance such as a water-soluble salt and coprecipitated when the nickel hydroxide powder is produced. There is no particular limitation on the reaction equipment for producing the nickel hydroxide powder, and any equipment that is normally used may be used, for example, as long as the pH can be controlled in a storage tank having a stirrer.
この水酸化ニッケル粉に含有されるアルカリ土類金属は、還元時におけるニッケル粒子生成時の粒子の微細化および球状化、さらには粒子表面の平滑性改善に効果がある。そのため水酸化ニッケル粉中のアルカリ土類金属の含有量は、０．００２〜１質量％が望ましい。アルカリ土類金属が０．００２質量％未満の場合には、微細化および平滑性改善の効果が見られず、アルカリ土類金属が１質量％を超えた場合には、得られるニッケル粉のニッケル品位の低下により、ＭＬＣＣ内部電極として用いられた場合に、電極の電気抵抗値が大きくなり過ぎ、コンデンサーの損失係数の悪化を招いてしまうことから限定するものである。 The alkaline earth metal contained in the nickel hydroxide powder is effective in making the particles finer and spheroidized when nickel particles are produced during reduction, and further improving the smoothness of the particle surface. Therefore, the content of alkaline earth metal in the nickel hydroxide powder is preferably 0.002 to 1% by mass. When the alkaline earth metal content is less than 0.002% by mass, the effect of refinement and smoothness improvement is not observed, and when the alkaline earth metal content exceeds 1% by mass, the resulting nickel powder is nickel. When used as an MLCC internal electrode due to the deterioration of quality, the electrical resistance value of the electrode becomes too large, which leads to deterioration of the loss factor of the capacitor.
［工程Ｂ］
工程Ｂは、工程Ａで得られた水酸化ニッケル粉から平均粒径１〜１００μｍの水酸化ニッケル粉群を構成し、この水酸化ニッケル粉群を２．１ｇ／ｃｍ２・ｓｅｃ以下の装入量で、３００〜１０００℃の非還元性ガス中に分散せしめた状態にして、酸化ニッケル粉への焙焼処理を行うと共に、非還元性ガスおよび酸化ニッケル粉の形成に伴い生成する水蒸気を、水酸化ニッケル１ｇに対して排気温度０〜５０℃の状態で０．２リットル／分以上の速度で排気する水酸化ニッケル粉の酸化ニッケル粉への焙焼工程である。
[Step B]
Step B constitutes a nickel hydroxide powder group having an average particle diameter of 1 to 100 μm from the nickel hydroxide powder obtained in Step A, and the nickel hydroxide powder group is charged at 2.1 g / cm 2 · sec or less. In a state where it is dispersed in a non-reducing gas at 300 to 1000 ° C. in an amount, it is subjected to roasting treatment to nickel oxide powder, and water vapor generated with the formation of the non-reducing gas and nickel oxide powder, This is a roasting step of nickel hydroxide powder to nickel oxide powder that is exhausted at a rate of 0.2 liters / minute or more at an exhaust temperature of 0 to 50 ° C. with respect to 1 g of nickel hydroxide.
工程Ｂにおいては、水酸化ニッケル粉を非還元性ガス中に分散した状態で酸化焙焼を行うが、その焙焼温度は３００〜１０００℃であることが好ましい。この温度範囲で酸化焙焼することにより、非還元性ガス中に分散している短時間においても十分に酸化ニッケル粉に還元することができ、３００℃未満の温度で酸化焙焼すると、転換が十分でなく水酸化ニッケル粉が残留する。
また、１０００℃を超える温度で酸化焙焼すると、焙焼処理中に焼結が進み粗大な酸化ニッケル粉となってしまう。このようにして得られた酸化ニッケル粉は、結晶が成長しているか粗大な粒径となっているため、還元するには高温で、かつ長時間還元させる必要が生じてしまう。高温、かつ長時間の還元を行った場合には、ニッケル粉の粒成長が進み、粗大で粒径が不均一なものとなる。
In step B, oxidation roasting is performed in a state where nickel hydroxide powder is dispersed in a non-reducing gas, and the roasting temperature is preferably 300 to 1000 ° C. By oxidative roasting in this temperature range, it can be sufficiently reduced to nickel oxide powder even in a short time dispersed in the non-reducing gas. Insufficient nickel hydroxide powder remains.
Moreover, if it oxidizes and roasts at the temperature exceeding 1000 degreeC, sintering will advance during a roasting process and will become coarse nickel oxide powder. Since the nickel oxide powder obtained in this way has grown crystals or has a coarse particle size, it needs to be reduced at a high temperature for a long time for reduction. When reduction is performed at a high temperature for a long time, the grain growth of nickel powder proceeds, resulting in a coarse and non-uniform particle size.
焙焼処理の時間は、十分に酸化ニッケル粉に転換され、酸化ニッケル粉の凝集あるいは粒成長が進行しない範囲に設定すればよいが、本発明の焙焼温度の範囲においては、４〜８秒とすることが好ましい。焙焼時間が４秒未満であると、酸化ニッケル粉への転換が十分でない場合がある。また、焙焼時間が８秒を越えると、酸化ニッケル粉の凝集あるいは粒成長が進行し、最終的に得られるニッケル粉の粒径が不均一になる場合がある。焙焼処理の時間、すなわち、水酸化ニッケル粉が焙焼温度領域を通過する時間は、焙焼温度領域の大きさ、排気速度により制御でき、温度領域が小さく、排気速度が大きい場合には、焙焼時間が短時間となり、温度領域が大きく、排気速度が小さい場合には、焙焼時間は長くなる。 The time for the roasting treatment may be set in a range in which the nickel oxide powder is sufficiently converted to nickel oxide powder and the aggregation or grain growth of the nickel oxide powder does not proceed. It is preferable that If the roasting time is less than 4 seconds, the conversion to nickel oxide powder may not be sufficient. Further, when the roasting time exceeds 8 seconds, the aggregation or grain growth of the nickel oxide powder proceeds, and the particle diameter of the finally obtained nickel powder may become non-uniform. The time for the roasting treatment, that is, the time for the nickel hydroxide powder to pass through the roasting temperature region can be controlled by the size of the roasting temperature region, the exhaust speed, and when the temperature region is small and the exhaust speed is large, When the roasting time is short, the temperature range is large, and the exhaust speed is small, the roasting time is long.
なお、酸化焙焼の焙焼処理を安定して行うためには、工程Ａで得られた水酸化ニッケル粉から、選択若しくは解砕などの加工を施して構成する平均粒径１〜１００μｍの水酸化ニッケル粉群を用いる。このような粒度を有する水酸化ニッケル粉を用いることで、非還元性ガス中での水酸化ニッケル粉の分散が良好となり、焙焼時の反応が安定するとともに、酸化焙焼時間を安定させることができる。粒度分布は、均一な酸化焙焼を行うために狭い方が好ましいが、特に粗大粒子を含まないことが好ましい。２００μｍを越えるような粗大粒子は、酸化焙焼が十分行われないことがあり、好ましくない。また、０．１μｍ未満の粒子も酸化焙焼時間が長くなることがあり、好ましくない。 In addition, in order to stably perform the roasting process of oxidation roasting, water having an average particle diameter of 1 to 100 μm constituted by processing such as selection or crushing from the nickel hydroxide powder obtained in step A is used. Nickel oxide powder group is used. By using nickel hydroxide powder having such a particle size, the dispersion of nickel hydroxide powder in non-reducing gas is improved, the reaction during roasting is stabilized, and the oxidation roasting time is stabilized. Can do. The particle size distribution is preferably narrow in order to perform uniform oxidation roasting, but it is particularly preferable that coarse particles are not included. Coarse particles exceeding 200 μm are not preferable because oxidation roasting may not be performed sufficiently. Also, particles having a size of less than 0.1 μm are not preferable because the oxidation roasting time may be increased.
［工程Ｃ］
工程Ｃは、工程Ｂで得られた酸化ニッケル粉を３００〜５００℃の温度で還元してニッケル粉を得る還元工程である。
その還元温度が５００℃を超えると、還元されたニッケル粉が還元中に焼結し、結果として粗大なニッケル粉が生成し、結果として所望の粒径のニッケル粉を精度良く得ることができない。他方、３００℃未満の温度では、酸化ニッケル粉からニッケル粉への還元が進みにくく、還元に長時間が必要となりニッケル粉の凝集が進んでしまう。還元温度を３００〜５００℃とすることで、均一で微細なニッケル粉が得られる。以上より、還元温度は、３００〜５００℃であることが好ましい。
[Step C]
Step C is a reduction step in which nickel oxide powder obtained in step B is reduced at a temperature of 300 to 500 ° C. to obtain nickel powder.
When the reduction temperature exceeds 500 ° C., the reduced nickel powder is sintered during the reduction, and as a result, coarse nickel powder is generated, and as a result, nickel powder having a desired particle diameter cannot be obtained with high accuracy. On the other hand, at a temperature lower than 300 ° C., the reduction from nickel oxide powder to nickel powder does not proceed easily, and a long time is required for the reduction, and the aggregation of nickel powder proceeds. By setting the reduction temperature to 300 to 500 ° C., uniform and fine nickel powder can be obtained. As mentioned above, it is preferable that reduction temperature is 300-500 degreeC.
使用する還元雰囲気の種類は、還元雰囲気であれば特に限定されるものではないが、不純物混入を防止するため、水素雰囲気とすることが好ましく、酸化ニッケル１ｇに対して０．０１〜０．２リットル／分の流量の水素が存在する水素濃度の水素雰囲気が好ましい。還元時に存在する水素量が酸化ニッケル１ｇに対して０．０１リットル／分未満の流量の場合には、還元が徐々に進むためにニッケル粉の粒成長が起こり、所望の粒径で均一なニッケル粉が得られず、他方、水素量が酸化ニッケル１ｇに対して０．２リットル／分を超えても、微細で均一な粒径のニッケル粉を得るために必要である還元を短時間化する効果の改善がなく、無駄な水素が増えコスト増となるのみである。 The type of reducing atmosphere to be used is not particularly limited as long as it is a reducing atmosphere. However, in order to prevent contamination with impurities, a hydrogen atmosphere is preferable, and 0.01 to 0.2 with respect to 1 g of nickel oxide. A hydrogen atmosphere with a hydrogen concentration in which hydrogen is present at a flow rate of liters / minute is preferred. When the amount of hydrogen present at the time of reduction is less than 0.01 liter / min with respect to 1 g of nickel oxide, the reduction proceeds gradually, so that nickel powder grain growth occurs, and uniform nickel with a desired particle diameter On the other hand, even if the amount of hydrogen exceeds 0.2 liter / min with respect to 1 g of nickel oxide, the reduction required for obtaining nickel powder having a fine and uniform particle size is shortened. There is no improvement in the effect, only wasteful hydrogen increases and costs increase.
なお、このとき水素ガスのみを流してもよいが、水素ガスと窒素、アルゴンなどの不活性ガスとの混合ガスを流すことは、より好ましい。
窒素などの不活性ガスとの混合ガスを用いることで、還元反応で発生する水蒸気を効率よく系外に排出させることができる。この場合、水素と混合する不活性ガスは、窒素のガスの場合、その容量比で水素１に対して０．５〜２とすることがコスト面を考慮すると好ましく、水素流量を考慮して系内で十分なガス流量が得られるようにすればよい。
At this time, only hydrogen gas may be flowed, but it is more preferable to flow a mixed gas of hydrogen gas and an inert gas such as nitrogen or argon.
By using a mixed gas with an inert gas such as nitrogen, water vapor generated by the reduction reaction can be efficiently discharged out of the system. In this case, when the inert gas mixed with hydrogen is a nitrogen gas, the volume ratio is preferably 0.5 to 2 with respect to hydrogen 1 in view of cost, and the system is considered in consideration of the hydrogen flow rate. In this case, a sufficient gas flow rate may be obtained.
還元時間は、特に限定されるものではなく、還元時に流す水素量、還元温度、投入する酸化ニッケル粉の量により、全ての酸化ニッケル粉がニッケル粉に還元されるのに必要な時間とすればよく、所望の粒径が得られるように時間を制御することが好ましい。また、還元に用いる設備は、雰囲気を制御できれば特に制限はなく、例えば、バッチ式雰囲気炉、バッチ式ロータリーキルン、連続式ローラーハースキルン、連続式プッシャー炉、連続式ロータリーキルンなどを用いることができる。 The reduction time is not particularly limited, and it may be a time required for all the nickel oxide powder to be reduced to nickel powder depending on the amount of hydrogen flowing during reduction, the reduction temperature, and the amount of nickel oxide powder to be added. It is preferable to control the time so that the desired particle size is obtained. The equipment used for the reduction is not particularly limited as long as the atmosphere can be controlled. For example, a batch type atmosphere furnace, a batch type rotary kiln, a continuous roller hearth kiln, a continuous pusher furnace, a continuous rotary kiln, or the like can be used.
この還元工程によって得られたニッケル粉は、粒径が微細でかつ均一であり粒子間の凝集も非常に少ないものであるが、工程中に生成した凝集粉の解砕あるいは工程中に混入した異物を除去する目的から、乾式または湿式による遠心力やフィルターを用いた解砕や分級を行ってもよい。用いられる装置は特に限定されるものではなく、通常のニッケル粉の製造に用いられるジェットミルやサイクロン形式の装置を使用する。 The nickel powder obtained by this reduction process has a fine and uniform particle size and very little agglomeration between the particles. However, the agglomerated powder produced during the process is crushed or foreign matter mixed during the process. For the purpose of removing water, crushing or classification using a dry or wet centrifugal force or a filter may be performed. The apparatus to be used is not particularly limited, and a jet mill or a cyclone type apparatus that is used for producing ordinary nickel powder is used.
以上、説明した本発明のニッケル粉の製造方法で得られるニッケル粉は、平均粒径が０．２〜０．４μｍであることが好ましい。すなわち、平均粒径が０．２μｍ未満であると、ＭＬＣＣ内部電極用ペーストとして用いたとき、ニッケル粉の焼結温度が低いため、誘電体セラミックスとの焼結挙動の差が大きく、電極の途切れや剥離が起こることがあり、他方、平均粒径が０．４μｍを超えると、薄層化された内部電極では、焼結後の電極に穴開きや途切れが発生することがあり好ましくないためである。平均粒径は、水酸化ニッケルに添加するマグネシウム量、還元温度等で容易に調製することができる。 As mentioned above, it is preferable that the nickel powder obtained by the manufacturing method of the nickel powder of this invention demonstrated that the average particle diameter is 0.2-0.4 micrometer. That is, when the average particle size is less than 0.2 μm, when used as a paste for MLCC internal electrodes, the sintering temperature of nickel powder is low, so the difference in sintering behavior with dielectric ceramics is large, and the electrodes are interrupted. On the other hand, if the average particle diameter exceeds 0.4 μm, the thinned internal electrode may cause holes or breaks in the sintered electrode, which is not preferable. is there. The average particle diameter can be easily prepared by the amount of magnesium added to nickel hydroxide, the reduction temperature, and the like.
以下に、本発明の実施例を用いて詳細に説明するが、本発明は、これらの実施例によって何ら限定されるものではない。
作製したニッケル粉の粒径の評価は以下のようにして行った。
走査型電子顕微鏡（ＪＳＭ−５５１０、日本電子製）で１００００倍の写真を撮影し、写真一視野で確認できる全ての粒子の粒径を測定し、統計処理を施して評価した。その評価項目は、粒子数基準で篩下１０％相当径（Ｄ１０）、篩下５０％相当径（Ｄ５０：平均粒径）、篩下９０％相当径（Ｄ９０）とした。
Hereinafter, the present invention will be described in detail using examples, but the present invention is not limited to these examples.
The particle diameter of the produced nickel powder was evaluated as follows.
A 10,000 times photograph was taken with a scanning electron microscope (JSM-5510, manufactured by JEOL Ltd.), and the particle diameters of all particles that could be confirmed in one field of view of the photograph were measured and subjected to statistical processing for evaluation. The evaluation items were 10% equivalent diameter under sieve (D10), 50% equivalent diameter under sieve (D50: average particle diameter), and 90% equivalent diameter under sieve (D90).
水酸化ニッケル粉の粒度分布は、レーザ光回折散乱式粒度分析計で測定して求め、体積積算５０％の粒径を平均粒径とし、測定された粒径の最大値を最大粒径とした。 The particle size distribution of the nickel hydroxide powder is determined by measuring with a laser light diffraction / scattering particle size analyzer, and the average particle size is 50% of the volume integral, and the maximum value of the measured particle size is the maximum particle size. .
１００ｇの塩化ニッケル６水和物（試薬１級、和光純薬製）と塩化マグネシウム６水和物（試薬１級、和光純薬製）０．２ｇ（水酸化ニッケル粉中のＭｇ含有量０．０６質量％相当）を純水２５０ｍｌに溶解して塩化ニッケル水溶液を調製した。次いで、水酸化ナトリウム（試薬１級、和光純薬製）３５．５ｇを純水２５０ｍｌに溶解した溶液を前記塩化ニッケル水溶液に添加し、生成した水酸化物をろ過した。さらに、これを１ｌの純水で水洗し、再びろ過した（以下、本操作を「ろ過水洗」と呼ぶ）。同様にろ過水洗を４回繰り返した後に、箱型大気乾燥機（ＤＸ６０１、ヤマト科学製）で１５０℃、４８時間の乾燥を行い、水酸化ニッケル粉を得た。 100 g of nickel chloride hexahydrate (reagent grade 1, manufactured by Wako Pure Chemical Industries) and magnesium chloride hexahydrate (reagent grade 1, manufactured by Wako Pure Chemical Industries) 0.2 g (Mg content in nickel hydroxide powder of 0. 06 mass%) was dissolved in 250 ml of pure water to prepare an aqueous nickel chloride solution. Next, a solution prepared by dissolving 35.5 g of sodium hydroxide (reagent grade 1, manufactured by Wako Pure Chemical Industries) in 250 ml of pure water was added to the nickel chloride aqueous solution, and the produced hydroxide was filtered. Further, this was washed with 1 l of pure water and filtered again (hereinafter, this operation is referred to as “filtered water washing”). Similarly, after washing with filtered water four times, drying was performed at 150 ° C. for 48 hours with a box-type atmospheric dryer (DX601, manufactured by Yamato Kagaku) to obtain nickel hydroxide powder.
得られた水酸化ニッケル粉を解砕し、平均粒径１６μｍ、最大粒径１００μｍの水酸化ニッケル粉群を構成した後、垂直型管状炉（均熱帯長５ｍ、管内径７ｃｍ径、東海高熱製タワーキルン）を用いて、この水酸化ニッケル粉を０．５２ｇ／ｃｍ２・分（２０ｇ／分を単位時間・単位面積当たりの装入量に換算致しました。（２０ｇ／（３．５ｃｍ×３．５ｃｍ×３．１４）））の割合で炉上部から落下させ、炉出口での空気と水蒸気からなる炉内ガスの排気量を水酸化ニッケル粉１ｇあたり０．３リットル／分とし、７００℃で焙焼して酸化ニッケル粉を得た。均熱帯を通過する時間を焙焼時間とし、焙焼時間は６秒であった。なお、２．０８ｇ／ｃｍ２・分の割合まで炉上部から落下させる水酸化ニッケル粉を増加させたが、酸化焙焼が十分に行われていることが確認された。 The obtained nickel hydroxide powder was crushed to form a nickel hydroxide powder group having an average particle diameter of 16 μm and a maximum particle diameter of 100 μm, and then a vertical tubular furnace (soaking zone 5 m, pipe inner diameter 7 cm, manufactured by Tokai Koyo Using a tower kiln, this nickel hydroxide powder was converted to 0.52 g / cm 2 · min (20 g / min was converted into a charge per unit time and unit area. (20 g / (3.5 cm × 3 0.5 cm × 3.14))), dropped from the top of the furnace, and the exhaust amount of the furnace gas consisting of air and water vapor at the outlet of the furnace was set at 0.3 liter / min per 1 g of nickel hydroxide powder, and 700 ° C. To obtain nickel oxide powder. The time to pass through the soaking zone was the roasting time, and the roasting time was 6 seconds. In addition, although nickel hydroxide powder dropped from the furnace upper part was increased to a rate of 2.08 g / cm 2 · min, it was confirmed that oxidation roasting was sufficiently performed.
次に、形成した酸化ニッケル粉１２ｇを、酸化ニッケル粉１ｇあたり０．１リットル／分の水素ガスと同量の窒素ガスを混合した混合ガス流したバッチ式雰囲気炉中に４５０℃で１時間保持して還元処理を施してニッケル粉を作製した。このニッケル粉を１００メッシュの篩にかけ、そのニッケル粉の粒径を走査型電子顕微鏡（以下、ＳＥＭ）により測定して、評価した。
水酸化ニッケル粉中のＭｇ添加量、焙焼条件および還元条件、ニッケル粉の粒径測定結果をまとめて表１に示す。
Next, 12 g of the formed nickel oxide powder is held at 450 ° C. for 1 hour in a batch-type atmosphere furnace in which a mixed gas of 0.1 liter / min of hydrogen gas and nitrogen gas mixed with the same amount of nitrogen gas flows. Then, reduction treatment was performed to produce nickel powder. The nickel powder was passed through a 100-mesh sieve, and the particle size of the nickel powder was measured by a scanning electron microscope (hereinafter, SEM) and evaluated.
Table 1 summarizes the amount of Mg added in the nickel hydroxide powder, roasting conditions and reduction conditions, and the particle size measurement results of the nickel powder.
塩化ニッケル水溶液に添加する塩化マグネシウム６水和物を０．１ｇ（水酸化ニッケル粉中のＭｇ含有量０．０２質量％相当）とした以外は、実施例１と同様にしてニッケル粉を得て、その粒径を測定した。
本実施例における水酸化ニッケル粉中のＭｇ含有量、焙焼条件および還元条件、ニッケル粉の粒径測定結果を表１に併せて示す。
Nickel powder was obtained in the same manner as in Example 1 except that 0.1 g of magnesium chloride hexahydrate added to the nickel chloride aqueous solution was changed to 0.1 g (equivalent to 0.02 mass% of Mg content in nickel hydroxide powder). The particle size was measured.
Table 1 also shows the Mg content in the nickel hydroxide powder, roasting conditions and reduction conditions, and the particle size measurement results of the nickel powder in this example.
焙焼温度を３００℃とした以外は、実施例１と同様にしてニッケル粉を得て、その粒径を測定した。
本実施例における水酸化ニッケル粉中のＭｇ含有量、焙焼条件および還元条件、ニッケル粉の粒径測定結果を表１に併せて示す。
Nickel powder was obtained in the same manner as in Example 1 except that the roasting temperature was 300 ° C., and the particle size was measured.
Table 1 also shows the Mg content in the nickel hydroxide powder, roasting conditions and reduction conditions, and the particle size measurement results of the nickel powder in this example.
焙焼温度を９００℃とした以外は、実施例１と同様にしてニッケル粉を得て、その粒径を測定した。
本実施例における水酸化ニッケル粉中のＭｇ含有量、焙焼条件および還元条件、ニッケル粉の粒径測定結果を表１に併せて示す。
Nickel powder was obtained in the same manner as in Example 1 except that the roasting temperature was 900 ° C., and the particle size was measured.
Table 1 also shows the Mg content in the nickel hydroxide powder, roasting conditions and reduction conditions, and the particle size measurement results of the nickel powder in this example.
焙焼時の前記排気量を０．２リットル／分とした以外は、実施例１と同様にしてニッケル粉を得て、その粒径を測定した。なお、焙焼時間は８秒であった。
本実施例における水酸化ニッケル粉中のＭｇ含有量、焙焼条件および還元条件、ニッケル粉の粒径測定結果を表１に併せて示す。
Nickel powder was obtained in the same manner as in Example 1 except that the exhaust amount at the time of roasting was 0.2 liter / min, and the particle size was measured. The roasting time was 8 seconds.
Table 1 also shows the Mg content in the nickel hydroxide powder, roasting conditions and reduction conditions, and the particle size measurement results of the nickel powder in this example.
焙焼時の前記排気量を２リットル/ 分とした以外は、実施例１と同様にしてニッケル粉を得て、その粒径を測定した。なお、焙焼時間は４秒であった。
本実施例における水酸化ニッケル粉中のＭｇ含有量、焙焼条件および還元条件、ニッケル粉の粒径測定結果を表１に併せて示す。
Nickel powder was obtained in the same manner as in Example 1 except that the amount of exhaust during roasting was 2 liters / minute, and the particle size was measured. The roasting time was 4 seconds.
Table 1 also shows the Mg content in the nickel hydroxide powder, roasting conditions and reduction conditions, and the particle size measurement results of the nickel powder in this example.
還元温度を３００℃で３時間とした以外は、実施例１と同様にしてニッケル粉を得て、その粒径を測定した。
本実施例における水酸化ニッケル粉中のＭｇ含有量、焙焼条件および還元条件、ニッケル粉の粒径測定結果を表１に併せて示す。
Nickel powder was obtained in the same manner as in Example 1 except that the reduction temperature was 300 ° C. for 3 hours, and the particle size was measured.
Table 1 also shows the Mg content in the nickel hydroxide powder, roasting conditions and reduction conditions, and the particle size measurement results of the nickel powder in this example.
還元温度を５００℃で０．５時間とした以外は、実施例１と同様にしてニッケル粉を得て、その粒径を測定した。
本実施例における水酸化ニッケル粉中のＭｇ含有量、焙焼条件および還元条件、ニッケル粉の粒径測定結果を表１に併せて示す。
Nickel powder was obtained in the same manner as in Example 1 except that the reduction temperature was 500 ° C. for 0.5 hour, and the particle size was measured.
Table 1 also shows the Mg content in the nickel hydroxide powder, roasting conditions and reduction conditions, and the particle size measurement results of the nickel powder in this example.
還元時に流す水素ガス流量を０．０１リットル／分として同量の窒素ガスと混合して流し、還元時間を３時間とした以外は、実施例１と同様にしてニッケル粉を得て、その粒径を測定した。
本実施例における水酸化ニッケル粉中のＭｇ含有量、焙焼条件および還元条件、ニッケル粉の粒径測定結果を表１に併せて示す。
Nickel powder was obtained in the same manner as in Example 1 except that the hydrogen gas flow rate at the time of reduction was 0.01 liters / minute and mixed with the same amount of nitrogen gas, and the reduction time was 3 hours. The diameter was measured.
Table 1 also shows the Mg content in the nickel hydroxide powder, roasting conditions and reduction conditions, and the particle size measurement results of the nickel powder in this example.
還元時に流す水素ガス流量を０．２リットル／分とし、同量の窒素ガスと混合して流した以外は、実施例１と同様にしてニッケル粉を得て、その粒径を測定した。
本実施例における水酸化ニッケル粉中のＭｇ含有量、焙焼条件および還元条件、ニッケル粉の粒径測定結果を表１に併せて示す。
Nickel powder was obtained in the same manner as in Example 1 except that the flow rate of hydrogen gas flowing at the time of reduction was 0.2 liters / minute and the mixture was mixed and flowed with the same amount of nitrogen gas, and the particle size was measured.
Table 1 also shows the Mg content in the nickel hydroxide powder, roasting conditions and reduction conditions, and the particle size measurement results of the nickel powder in this example.
［比較例１］
塩化ニッケル水溶液を塩化ニッケル６水和のみで調整した以外は、実施例１と同様にしてニッケル粉を得て、その粒径を測定した。
本比較例における水酸化ニッケル粉中のＭｇ含有量、焙焼条件および還元条件、ニッケル粉の粒径測定結果を表１に併せて示す。
[Comparative Example 1]
Nickel powder was obtained in the same manner as in Example 1 except that the aqueous nickel chloride solution was adjusted only with nickel chloride hexahydrate, and the particle size was measured.
Table 1 also shows the Mg content in the nickel hydroxide powder, roasting conditions and reduction conditions, and the particle size measurement results of the nickel powder in this comparative example.
［比較例２］
焙焼時の前記排気量を０．１リットル／分とした以外は、実施例１と同様にしてニッケル粉を得て、その粒径を測定した。
本比較例における水酸化ニッケル粉中のＭｇ含有量、焙焼条件および還元条件、ニッケル粉の粒径測定結果を表１に併せて示す。
[Comparative Example 2]
Nickel powder was obtained in the same manner as in Example 1 except that the exhaust amount at the time of roasting was 0.1 liter / min, and the particle size was measured.
Table 1 also shows the Mg content in the nickel hydroxide powder, roasting conditions and reduction conditions, and the particle size measurement results of the nickel powder in this comparative example.
［比較例３］
焙焼温度を２５０℃とした以外は、実施例１と同様にしてニッケル粉を得て、その粒径を測定した。
本比較例における水酸化ニッケル粉中のＭｇ含有量、焙焼条件および還元条件、ニッケル粉の粒径測定結果を表１に併せて示す。
[Comparative Example 3]
Nickel powder was obtained in the same manner as in Example 1 except that the roasting temperature was 250 ° C., and the particle size was measured.
Table 1 also shows the Mg content in the nickel hydroxide powder, roasting conditions and reduction conditions, and the particle size measurement results of the nickel powder in this comparative example.
［比較例４］
焙焼温度を１１００℃とした以外は、実施例１と同様にしてニッケル粉を得て、その粒径を測定した。
本比較例における水酸化ニッケル粉中のＭｇ含有量、焙焼条件および還元条件、ニッケル粉の粒径測定結果を表１に併せて示す。
[Comparative Example 4]
Nickel powder was obtained in the same manner as in Example 1 except that the roasting temperature was 1100 ° C., and the particle size was measured.
Table 1 also shows the Mg content in the nickel hydroxide powder, roasting conditions and reduction conditions, and the particle size measurement results of the nickel powder in this comparative example.
［比較例５］
還元時に流す水素ガス流量を０．００５リットル／分として同量の窒素ガスと混合して流した以外は、実施例１と同様にしてニッケル粉を得て、その粒径を測定した。
本比較例における水酸化ニッケル粉中のＭｇ含有量、焙焼条件および還元条件、ニッケル粉の粒径測定結果を表１に併せて示す。
[Comparative Example 5]
Nickel powder was obtained in the same manner as in Example 1 except that the flow rate of hydrogen gas flowing at the time of reduction was 0.005 liters / minute and mixed with the same amount of nitrogen gas, and the particle size was measured.
Table 1 also shows the Mg content in the nickel hydroxide powder, roasting conditions and reduction conditions, and the particle size measurement results of the nickel powder in this comparative example.
［比較例６］
還元条件を２５０℃で３時間とした以外は、実施例１と同様にしてニッケル粉を得て、その粒径を測定した。
本比較例における水酸化ニッケル粉中のＭｇ含有量、焙焼条件および還元条件、ニッケル粉の粒径測定結果を表１に併せて示す。
[Comparative Example 6]
Nickel powder was obtained in the same manner as in Example 1 except that the reduction condition was 250 ° C. for 3 hours, and the particle size was measured.
Table 1 also shows the Mg content in the nickel hydroxide powder, roasting conditions and reduction conditions, and the particle size measurement results of the nickel powder in this comparative example.
［比較例７］
還元条件を６００℃で０．５時間とした以外は、実施例１と同様にしてニッケル粉を得て、その粒径を測定した。
本比較例における水酸化ニッケル粉中のＭｇ含有量、焙焼条件および還元条件、ニッケル粉の粒径測定結果を表１に併せて示す。
[Comparative Example 7]
Nickel powder was obtained in the same manner as in Example 1 except that the reducing condition was changed to 600 ° C. for 0.5 hour, and the particle size was measured.
Table 1 also shows the Mg content in the nickel hydroxide powder, roasting conditions and reduction conditions, and the particle size measurement results of the nickel powder in this comparative example.
［比較例８］
焙焼時に用いる炉をバッチ式雰囲気炉（管状炉、入江製作所製）とし、乾燥水酸化ニッケル粉１５ｇを水酸化ニッケル粉１ｇあたり空気流量を０．２リットル／分とし、４５０℃で６時間保持して焙焼して酸化ニッケル粉を得た以外は実施例１と同様にしてニッケル粉を得て、その粒径を測定した。
本比較例における水酸化ニッケル粉中のＭｇ含有量、焙焼条件および還元条件、ニッケル粉の粒径測定結果を表１に併せて示す。
[Comparative Example 8]
The furnace used for roasting is a batch-type atmosphere furnace (tubular furnace, manufactured by Irie Seisakusho), 15 g of dried nickel hydroxide powder is 0.2 liter / min per 1 g of nickel hydroxide powder, and held at 450 ° C. for 6 hours. Then, nickel powder was obtained in the same manner as in Example 1 except that nickel oxide powder was obtained by baking, and the particle size was measured.
Table 1 also shows the Mg content in the nickel hydroxide powder, roasting conditions and reduction conditions, and the particle size measurement results of the nickel powder in this comparative example.
表１からも明らかなように、本発明に係る製造方法で得られた実施例１から１０のニッケル粉は、平均粒径（Ｄ５０）が０．３〜０．５μｍでシャープな粒度分布が得られている。これに対して、比較例１から７のニッケル粉では、Ｄ９０が実施例よりも大きく粗大なニッケル粉が含まれていることがわかる。 As is clear from Table 1, the nickel powders of Examples 1 to 10 obtained by the production method according to the present invention have a mean particle size (D50) of 0.3 to 0.5 μm and a sharp particle size distribution. It has been. On the other hand, it can be seen that the nickel powders of Comparative Examples 1 to 7 contain nickel powder having a larger D90 than the examples and coarser.
したがって、比較例１から７のニッケル粉は、粗大粒子が含まれることからＭＬＣＣ内部電極用ニッケル粉として好ましくないことがわかる。また、従来のバッチ式による焙焼を採用した比較例８では、実施例と同様の粒度分布を持つニッケル粉が得られているものの、焙焼時間が６時間と極めて長く、生産性が極度に低下しており、本実施例での低コストに対する優位性が明確である。 Therefore, it can be seen that the nickel powders of Comparative Examples 1 to 7 are not preferable as the nickel powder for MLCC internal electrodes because coarse particles are included. Further, in Comparative Example 8 employing conventional batch-type roasting, although nickel powder having the same particle size distribution as in the example was obtained, the roasting time was extremely long as 6 hours, and the productivity was extremely high. It is lowered and the superiority to the low cost in this embodiment is clear.
Claims (7)
工程Ａとして、
ニッケル塩を含む水溶液を中和晶析してアルカリ土類金属を０．００２〜１質量％含む水酸化ニッケル粉の形成工程と、
工程Ｂとして、
前記水酸化ニッケル粉から平均粒径１〜１００μｍの水酸化ニッケル粉群を構成し、前記水酸化ニッケル粉群を非還元性ガス中に上方から落下させ、２．１ｇ／ｃｍ２・ｓｅｃ以下の装入量により３００〜１０００℃の該非還元性ガス中に分散せしめた状態で酸化ニッケル粉へと焙焼処理すると共に、前記非還元性ガスおよび前記酸化ニッケル粉の焙焼処理により生じる水蒸気を水酸化ニッケル粉１ｇに対して排気温度０〜５０℃の状態で０．２リットル／分以上の速度で排気する水酸化ニッケル粉の酸化ニッケル粉への焙焼工程と、
工程Ｃとして、
前記酸化ニッケル粉を、３００〜５００℃の温度で還元処理してニッケル粉を形成する還元工程と
を含むことを特徴とするニッケル粉の製造方法。 In the nickel powder production method of roasting nickel hydroxide powder containing alkaline earth metal to nickel oxide powder, reducing the nickel oxide powder to nickel powder,
As process A,
A step of forming nickel hydroxide powder containing 0.002 to 1% by mass of an alkaline earth metal by neutralizing and crystallizing an aqueous solution containing a nickel salt;
As process B,
A nickel hydroxide powder group having an average particle diameter of 1 to 100 μm is constituted from the nickel hydroxide powder, and the nickel hydroxide powder group is dropped into the non-reducing gas from above, and is 2.1 g / cm 2 · sec or less the charged amount with roasting process to nickel oxide powder in a state of dispersed in said non-reducing gas 300 to 1000 ° C., the steam generated by the roasting of the non-reducing gas and the nickel oxide powder Roasting of nickel hydroxide powder into nickel oxide powder exhausted at a rate of 0.2 liters / minute or more at a temperature of 0 to 50 ° C. with respect to 1 g of nickel hydroxide powder;
As process C,
The nickel oxide powder includes a reduction step of reducing the nickel oxide powder at a temperature of 300 to 500 ° C. to form nickel powder.
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| JP2004315273A (en) * | 2003-04-15 | 2004-11-11 | Sumitomo Metal Mining Co Ltd | Nickel oxide powder with high specific surface area and excellent sintering property and its manufacturing method |
| JP4063151B2 (en) * | 2003-06-11 | 2008-03-19 | 住友金属鉱山株式会社 | Porous spherical nickel powder and method for producing the same |
| CN101163937A (en) * | 2005-06-16 | 2008-04-16 | 东海高热工业株式会社 | Vertical firing furnace and firing method using it |
| JP5176222B2 (en) * | 2006-12-07 | 2013-04-03 | 東海高熱工業株式会社 | Vertical firing furnace and firing method using the same |
| JP4978785B2 (en) * | 2007-07-17 | 2012-07-18 | 住友金属鉱山株式会社 | Method for producing nickel powder |
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2009
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