JP2011225395A - Nickel oxide fine powder, and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nickel oxide fine powder which has a controlled sulfur grade, a low chlorine grade and is minute and suitable as an electronic component material, and to provide an industrially stable method for producing the nickel oxide fine powder.SOLUTION: An aqueous nickel sulfate solution is neutralized with an alkali, the resulting nickel hydroxide is heat-treated at a temperature of >850 to <1,200°C in a nonreducing atmosphere to form nickel oxide particles, and sintered bodies of nickel oxide particles which may be formed in the heat treatment are crushed preferably by collision of the particles with each other. The resulting nickel oxide fine powder has a sulfur grade of ≤400 mass ppm, a chlorine grade of ≤50 mass ppm, a sodium grade of ≤100 mass ppm and a specific surface area of 2-7 m/g.

Description

  TECHNICAL FIELD The present invention relates to nickel oxide fine powder and a method for producing the same, and more particularly, sulfur grade is controlled, impurity grade, particularly chlorine grade and sodium grade are low and fine, and electronic components and solid oxide fuels. The present invention relates to a nickel oxide fine powder suitable as a material used for a battery electrode and a method for producing the same.

  In general, nickel oxide powder is made of nickel salts such as nickel sulfate, nickel nitrate, nickel carbonate, nickel hydroxide, or nickel metal powder. It is manufactured by firing in an oxidizing atmosphere using a simple batch furnace. These nickel oxide powders are used in various applications as materials used for electronic parts, electrodes of solid oxide fuel cells, and the like.

  For example, in applications as electronic component materials, they are widely used as ferrite components by being mixed with other materials such as iron oxide and zinc oxide and then sintered. In the case of producing a composite metal oxide by mixing and firing a plurality of materials as in the above ferrite parts, the production reaction is limited by a solid phase diffusion reaction. A fine material is suitably used as the raw material to be used. This increases the probability of contact with other materials and increases the activity of the particles, so that it is known that the reaction proceeds uniformly at a low temperature for a short time. Therefore, in such a method for producing a composite metal oxide, it is an important factor for improving efficiency to reduce the particle size of the raw material powder to be fine.

  A solid oxide fuel cell is expected as a new power generation system from both environmental and energy viewpoints, and nickel oxide powder is used as the electrode material. In general, a cell stack of a solid oxide fuel cell has a structure in which single cells each having an air electrode, a solid electrolyte, and a fuel electrode are sequentially stacked. Usually, as the fuel electrode, for example, a mixture of nickel or nickel oxide and a solid electrolyte made of stabilized zirconia is used. The fuel electrode is reduced by fuel gas such as hydrogen or hydrocarbon during power generation to become nickel metal, and the three-phase interface consisting of nickel, solid electrolyte and voids becomes the reaction field of fuel gas and oxygen. Similarly, reducing the particle size of the raw material powder to make it fine is an important factor for improving power generation efficiency.

  By the way, a specific surface area may be used as an index for measuring that the powder is fine. Further, it is known that there is a relationship of the following calculation formula 1 between the particle size and the specific surface area. Since the relationship of the following calculation formula 1 is derived on the assumption that the particles are spherical, there is some error between the particle size obtained from calculation formula 1 and the actual particle size. However, the larger the specific surface area, the smaller the particle size.

[Calculation Formula 1]
Particle size = 6 / (density × specific surface area)

  In recent years, reduction in impurity elements contained in nickel oxide powder has been demanded as ferrite parts have higher functionality and use of nickel oxide powder for electronic parts other than ferrite parts has been increasing. Among the impurity elements, especially chlorine and sulfur react with silver used for the electrode, which may cause electrode deterioration or corrode the firing furnace. .

  On the other hand, JP-A-2002-198213 (Patent Document 1) discloses a ferrite material in which the content of the sulfur component of the ferrite powder in the raw material stage is 300 ppm to 900 ppm in terms of S and the content of the chlorine component is 100 ppm in terms of Cl. Proposed. This ferrite material can be densified without using additives even in low-temperature firing, and the ferrite core and multilayer chip component formed thereby should have excellent moisture resistance and temperature characteristics. It is stated that it can be done.

  As described above, nickel oxide powder is required to reduce the content of chlorine and sulfur. Furthermore, in the case of nickel oxide powder used as an electronic component material, particularly as a raw material for ferrite components, not only the sulfur content is reduced, but also the sulfur content is strictly controlled within a predetermined range. That is also required. As described above, in the nickel oxide powder used as the electronic component material, it is necessary to refine the particle size, reduce impurities, and strictly control the sulfur content.

  Conventionally, as a method for producing such characteristic nickel oxide powder, a method of using nickel sulfate as a raw material and baking it has been proposed. For example, Japanese Patent Laid-Open No. 2001-32002 (Patent Document 2) discloses a first stage roasting in which nickel sulfate as a raw material is roasted at a roasting temperature of less than 950 to 1000 ° C. in an oxidizing atmosphere using a kiln or the like. And the method of performing the 2nd stage roasting roasted at the roasting temperature 1000-1200 degreeC, and manufacturing the nickel oxide powder is proposed. According to this manufacturing method, it is described that a nickel oxide fine powder having an average particle size controlled and a sulfur quality of 50 mass ppm or less can be obtained.

  JP 2004-123488 A (Patent Document 3) discloses nickel oxide in which a dehydration process by calcining at 450 to 600 ° C. and a decomposition process of nickel sulfate by roasting at 1000 to 1200 ° C. are clearly separated. A method for producing a powder has been proposed. According to this production method, it is described that nickel oxide powder having a low sulfur quality and a small average particle diameter can be produced stably.

  Furthermore, Japanese Patent Laid-Open No. 2004-189530 (Patent Document 4) proposes a method of roasting at a maximum temperature of 900 to 1250 ° C. while forcibly introducing air using a horizontal rotary manufacturing furnace. ing. It is described that nickel oxide powder with few impurities and a sulfur quality of 500 mass ppm or less can be obtained by this manufacturing method.

  However, in any of the methods of Patent Documents 2 to 4, when the roasting temperature is increased to reduce the sulfur quality, the particle size becomes coarse, and when the roasting temperature is decreased to make the particles finer, sulfur There is a drawback that the quality becomes high, and it is difficult to simultaneously control the particle size and sulfur quality to the optimum values. Furthermore, there is a problem in that a gas containing a large amount of SOx is generated during heating, and expensive equipment is required to remove the gas.

  As a method of synthesizing fine nickel oxide powder, an aqueous solution containing nickel salts such as nickel sulfate and nickel chloride is neutralized with an alkali such as an aqueous sodium hydroxide solution to crystallize nickel hydroxide and roasted. Is also possible. When nickel hydroxide is roasted by such a method, it is considered that exhaust gas treatment is unnecessary or simple equipment can be manufactured at low cost because there is little generation of anion component-derived gas. .

  For example, JP 2009-196870 A (Patent Document 5) discloses neutralization in a state where a small amount of a Group 2 element such as magnesium is added to nickel chloride in order to suppress the coarsening of nickel oxide. Nickel is heat-treated at a specific temperature to obtain nickel oxide, and the obtained nickel oxide is wet-ground with a pulverization medium and washed with an organic acid-containing aqueous solution, so that the sulfur quality and chlorine quality are low and fine. A method for obtaining a nickel oxide powder having a particle size has been proposed.

JP 2002-198213 A Japanese Patent Laid-Open No. 2001-032002 JP 2004-123488 A JP 2004-189530 A JP 2009-196870 A

  However, in the method for producing the nickel oxide powder of Patent Document 5, sulfur can be reduced because nickel chloride is used as a raw material, but it was difficult to control the sulfur quality within a predetermined range. Moreover, since wet grinding is performed with a crushing media in order to obtain a fine particle size, there is a possibility that impurities are mixed from the crushing media. Thus, the nickel oxide powder obtained by the conventional technology is not sufficient as a nickel oxide powder having a fine particle size, low chlorine quality and controlled sulfur quality, and further improvement is desired. It was rare.

  In view of the above-described problems, the present invention contains a small amount of sulfur with a controlled content, has low impurity quality, particularly chlorine quality, and has a fine particle size, and is an electronic component material or solid oxide fuel. An object of the present invention is to provide a nickel oxide fine powder suitable as an electrode material for a battery and a method for producing the same.

  In order to achieve the above object, the present inventors produce nickel oxide fine powder by roasting nickel hydroxide obtained by neutralizing an aqueous nickel salt solution in a method in which a large amount of harmful gas is not generated during heat treatment. As a result of earnest research focusing on the method, the sulfuric acid quality was controlled by neutralizing the nickel sulfate aqueous solution with alkali and heat-treating the obtained nickel hydroxide under the specified conditions, and the impurity quality, especially the chlorine quality The inventors have found that a fine nickel oxide powder having a low particle size can be obtained, and have completed the present invention.

  That is, the method for producing a nickel oxide fine powder provided by the present invention comprises a step A in which an aqueous nickel sulfate solution is neutralized with an alkali to obtain nickel hydroxide, and the obtained nickel hydroxide is 850 ° C. in a non-reducing atmosphere. And a step B of forming nickel oxide particles by heat treatment at a temperature of more than 1200 ° C. and a step C of crushing a sintered body of nickel oxide particles that can be formed during the heat treatment. Is.

  The nickel concentration in the nickel sulfate aqueous solution in the step A is preferably 50 to 180 g / L, and the crushing in the step C is preferably performed by causing nickel oxide particles to collide with each other.

Moreover, the nickel oxide fine powder provided by the present invention is a nickel oxide fine powder obtained by the above-described method for producing a nickel oxide fine powder, having a specific surface area of ² to 7 m ² / g and a sulfur quality of 400 mass ppm or less. The chlorine quality is 50 mass ppm or less and the sodium quality is 100 mass ppm or less. The nickel oxide fine powder of the present invention preferably has a D90 measured by a laser scattering method of 3 μm or less.

  According to the present invention, sulfur quality is controlled at 400 mass ppm or less, chlorine quality is 50 mass ppm or less, sodium quality is less than 100 mass ppm, impurity quality is low, and fine nickel oxide fine powder can be easily obtained. Can do. Furthermore, the nickel oxide fine powder of the present invention is fine without substantially containing zirconium and Group 2 elements as impurities, and is suitable as an electronic component material such as a ferrite component or an electrode material of a solid oxide fuel cell. It is. Moreover, the manufacturing method is also easy without generating a large amount of chlorine or SOx gas, and its industrial value is extremely large.

  The nickel oxide fine powder production method of the present invention comprises a step A in which a nickel sulfate aqueous solution is neutralized with an alkali to obtain nickel hydroxide, and the obtained nickel hydroxide is heated to a temperature exceeding 850 ° C. and 1200 ° C. in a non-reducing atmosphere. A step B in which nickel oxide particles are formed by heat treatment at a temperature below, and a step C in which a sintered body of nickel oxide particles that can be formed during the heat treatment is crushed.

  In the production method of the present invention, it is particularly important to use nickel sulfate as a raw material in Step A. By using nickel sulfate in the nickel salt aqueous solution, it becomes possible to obtain fine nickel oxide powder even when the heat treatment temperature is increased, compared with the case of using other nickel salts, and therefore, the fine and sulfur quality can be obtained. Controlled nickel oxide fine powder is obtained. That is, the present inventors have found that the effect of the heat treatment temperature on the particle size can be suppressed by the effect of the sulfur component, and as a result, the sulfur quality of nickel oxide can be controlled by the heat treatment temperature while maintaining a fine particle size. It was. Furthermore, since this method does not use nickel chloride, there is no possibility that chlorine will be mixed in, and it is possible to obtain nickel oxide fine powder that substantially does not contain chlorine except for impurities inevitably contained in the raw material.

  The clear reason why a fine nickel oxide powder having a fine particle diameter can be obtained by the above method is unknown, but since the decomposition temperature of nickel sulfate is as high as 848 ° C., as a sulfate on the surface and interface in nickel hydroxide. It is considered that a sulfur component is entrained and this suppresses the sintering of the nickel oxide particles to a high temperature.

By the heat treatment, the hydroxyl group in the nickel hydroxide crystal is desorbed and nickel oxide particles are formed. At this time, by appropriately setting the heat treatment temperature, it is possible to refine the particle size and control the sulfur quality. is there. Specifically, by setting the heat treatment temperature of nickel hydroxide to more than 850 ° C. and less than 1200 ° C., the sulfur quality of the nickel oxide fine powder is controlled to 400 mass ppm or less, and the specific surface area is ² to 7 m ² / g. can do. In particular, when the sulfur quality is controlled to less than 100 ppm by mass, the temperature is preferably 910 ° C. or higher. In either case, the desired sulfur quality can be obtained by appropriately adjusting the heat treatment temperature within the above temperature range.

  When the heat treatment temperature is 1200 ° C. or higher, the decomposition of the sulfur component proceeds, and the effect of suppressing the sintering becomes insufficient, and the acceleration of sintering due to temperature becomes remarkable. As a result, the sintering of the nickel oxide particles obtained by the heat treatment in the process B becomes remarkable, and it becomes difficult to crush the sintered body of the nickel oxide particles in the process C. Nickel oxide fine powder having a specific surface area cannot be obtained. On the other hand, when the heat treatment temperature of the nickel hydroxide is 850 ° C. or lower, the volatilization of the sulfur component due to the decomposition of the sulfur component such as sulfate is insufficient, and the sulfur component remains in the nickel hydroxide. The sulfur grade of powder exceeds 400 mass ppm.

  Next, the method for producing nickel oxide of the present invention will be described in detail for each step. First, Step A is a step of obtaining nickel hydroxide by neutralizing an aqueous nickel sulfate solution with an alkali, and known techniques can be applied to the concentration and neutralization conditions. Nickel sulfate used as a raw material is not particularly limited, but since the obtained nickel oxide fine powder is used for electronic parts or for electrodes of solid oxide fuel cells, the raw material is used to prevent corrosion. It is desirable that the impurities contained therein are less than 100 mass ppm.

  The alkali used for neutralization is not particularly limited, but sodium hydroxide, potassium hydroxide and the like are preferable in consideration of the amount of nickel remaining in the reaction solution. Particularly preferred. The alkali may be added to the nickel salt aqueous solution in a solid or liquid state, but it is preferable to use an aqueous solution for ease of handling.

  In order to obtain nickel hydroxide having uniform characteristics, a nickel salt aqueous solution and an alkaline aqueous solution are added to a sufficiently stirred liquid in the reaction tank by a double jet method, that is, the nickel salt aqueous solution or Prepare one of the aqueous alkali solutions and neutralize it by adding the other aqueous alkali salt solution or nickel salt aqueous solution, but in the solution sufficiently stirred in the reaction vessel, the nickel salt aqueous solution and the alkaline aqueous solution It is effective to adopt a method in which and are continuously added. In that case, it is preferable that the liquid previously put in the reaction tank is adjusted to a predetermined pH by adding alkali to pure water.

  During the neutralization reaction, the pH of the reaction solution is preferably set in the range of 8.3 to 9.0, and it is particularly preferable to keep the pH substantially constant within this range. When this pH is lower than 8.3, anion components such as sulfate ions remaining in nickel hydroxide increase, and when firing in the process B, they become a large amount of hydrochloric acid and SOx and damage the furnace body. Therefore, it is not preferable. On the other hand, if the pH is higher than 9.0, the resulting nickel hydroxide may become too fine, and subsequent filtration may be difficult. Moreover, sintering may progress too much at the process B performed later, and it may become difficult to obtain fine nickel oxide fine powder.

  At a pH of 9.0 or less, which is a suitable neutralization condition, a slight amount of nickel component may remain in the aqueous solution. In this case, the nickel in the filtrate is increased by raising the pH to about 10 after neutralization crystallization. Can be reduced. The pH during the neutralization reaction is preferably controlled to be constant so that the fluctuation range is within an absolute value of 0.2 around the set value. If the fluctuation range of the pH is larger than this, there is a risk of increasing impurities and reducing the specific surface area of the nickel oxide fine powder.

  Further, the concentration of nickel in the aqueous nickel sulfate solution prepared in step A is not particularly limited, but considering productivity, the nickel concentration is preferably 50 to 180 g / L. If this concentration is less than 50 g / L, the productivity will deteriorate. On the other hand, if it exceeds 180 g / L, the anion concentration in the aqueous solution becomes too high and the sulfur quality in the produced nickel hydroxide becomes high, so the impurity quality in the finally obtained nickel oxide fine powder is sufficiently low. It may not be possible.

  The liquid temperature during the neutralization reaction can be carried out at room temperature under normal conditions without any particular problem, but is preferably 50 to 70 ° C. in order to sufficiently grow nickel hydroxide particles. By sufficiently growing the nickel hydroxide particles, it is possible to prevent excessive inclusion of sulfur in the nickel hydroxide. Further, it is possible to suppress the inclusion of impurities such as sodium into the nickel hydroxide, and finally reduce the impurities of the nickel oxide fine powder.

  When the liquid temperature is less than 50 ° C., the nickel hydroxide particles are not sufficiently grown, and the inclusion of sulfur and impurities in the nickel hydroxide increases. On the other hand, if the liquid temperature exceeds 70 ° C., the evaporation of water becomes vigorous and the concentration of sulfur and impurities in the aqueous solution increases, so that the sulfur quality and impurity quality in the produced nickel hydroxide may increase.

  After completion of the neutralization reaction, the precipitated nickel hydroxide is collected by filtration. The recovered filter cake is preferably washed before moving to the next step B. The washing is preferably repulp washing, and the washing liquid used for washing is preferably water, and particularly preferably pure water. The mixing ratio of nickel hydroxide and water at the time of washing is not particularly limited, and may be a mixing ratio that can sufficiently remove anions, particularly sulfate ions and sodium components contained in the nickel salt. In addition, when anion and a sodium component are not fully reduced by one washing | cleaning, it is preferable to wash | clean repeatedly several times. In particular, since sodium cannot be removed by the heat treatment in the next step B, it is preferable to remove it sufficiently by washing.

  The specific amount of the cleaning solution for nickel hydroxide is 50 to 150 g of nickel hydroxide so that impurities such as residual anions and sodium components can be sufficiently reduced and nickel hydroxide is well dispersed. It is preferable to mix 1 L, and it is more preferable to mix 1 L of cleaning liquid with respect to about 100 g of nickel hydroxide. The cleaning time can be appropriately determined according to the processing conditions, and may be a time during which residual impurities are sufficiently reduced.

  Next, the process B is a process for obtaining nickel oxide by heat-treating the nickel hydroxide obtained in the process A. This heat treatment is performed in a non-reducing atmosphere in a temperature range higher than 850 ° C. and lower than 1200 ° C. The atmosphere 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. Moreover, in order to discharge efficiently the water vapor | steam which generate | occur | produces by the detachment | desorption of a hydroxyl group at the time of heat processing, it is preferable to carry out in the airflow with sufficient flow velocity. In addition, a general roasting furnace can be used for the apparatus which performs heat processing.

The heat treatment time can be appropriately set according to the processing conditions such as the processing temperature and the processing amount, but if the specific surface area of the finally obtained nickel oxide fine powder is set to ² to 7 m ² / g. Good. Since the specific surface area of the nickel oxide fine powder finally obtained by pulverization is about 1 m ² / g higher than the specific surface area of the nickel oxide after the heat treatment, the specific surface area of the nickel oxide after the heat treatment is judged. And processing conditions can be set.

  Next, Step C is a step of crushing a sintered body of nickel oxide particles that can be formed during the heat treatment in Step B. In Step B, the hydroxyl group in the nickel hydroxide crystal is released to form nickel oxide particles. At that time, the particle size is reduced and the sulfuric acid component suppresses the effect, but the effect of high temperature. The sintering of nickel oxide particles proceeds to some extent. In order to destroy the sintered body, in step C, the nickel oxide after the heat treatment is crushed to obtain nickel oxide fine powder.

  General crushing methods include those using crushing media such as bead mills and ball mills, and those that do not use crushing media such as jet mills. In the production method of the present invention, the latter crushing media are used. It is preferable to employ a crushing method that does not use s. This is because, when the crushing media is used, crushing itself is easy, but components constituting the crushing media such as zirconia may be mixed as impurities. In particular, when using nickel oxide fine powder for electronic parts, it is preferable to employ a crushing method that does not use crushing media.

  If the impurity to be reduced is only zirconium, it can be dealt with by crushing using a crushed media that does not contain zirconium, such as zirconia. As a result, low-impurity nickel oxide fine powder cannot be obtained. In addition, crushed media containing no zirconium, for example, crushed media containing no yttria-stabilized zirconia is not sufficient in strength and wear resistance, and from this point of view, there is a method of crushing without using a crushed media. desirable.

  As a method of crushing without using a crushing media, there are a method of colliding powder particles, a method of applying a shearing force to a powder with a solvent such as a liquid, a method of using an impact force due to cavitation of a solvent, etc. is there. Examples of the crushing device that collides particles of powder include 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). The latter includes Optimizer (registered trademark), Starburst (registered trademark), and the like. In addition, as a crushing device that applies a shearing force by a solvent, for example, there is Nanomizer (registered trademark), and as a crushing device that uses an impact force by cavitation of a solvent, for example, a nano manufacturer (registered trademark) or the like Can be mentioned.

  Among the above-mentioned pulverization methods, a method of causing powder particles to collide with each other is particularly preferable because there is little possibility of mixing impurities and a relatively large pulverization force can be obtained. Thus, by performing crushing without using a crushing medium, it is possible to obtain a fine nickel oxide fine powder that is substantially free of impurities from the crushing medium, particularly zirconium.

  Crushing conditions are not particularly limited, and fine nickel oxide powder having a desired particle size distribution can be easily obtained by adjustment within the range of normal conditions. Thereby, the fine nickel oxide fine powder excellent in the dispersibility suitable as electronic component materials, such as a ferrite component, can be obtained.

The nickel oxide fine powder of the present invention produced by the above method does not include a step of mixing chlorine in addition to mixing as impurities from the raw material, so that the chlorine quality is extremely low. In addition, the sulfur quality is controlled, the sodium quality is low, and the specific surface area is large. Specifically, the sulfur quality is 400 mass ppm or less, the chlorine quality is 50 mass ppm or less, and the sodium quality is 100 mass ppm or less. The specific surface area is ² to 7 m ² / g. 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. The electrode material for the solid oxide fuel cell preferably has a sulfur quality of 100 mass ppm or less.

  Moreover, in the manufacturing method of the nickel oxide fine powder of this invention, since the process of adding Group 2 elements, such as magnesium, is not included, these elements are not substantially contained as an impurity. Furthermore, when crushing without using a crushing media, zirconia is not included, so that the zirconia quality and the Group 2 element quality can be reduced to 30 ppm by mass or less.

  Furthermore, the nickel oxide fine powder of the present invention preferably has a D90 (particle diameter at a volume integration of 90% of the particle amount in the particle size distribution curve) measured by a laser scattering method of 3 μm or less. D90 measured by the laser scattering method is crushed and reduced when mixed with other materials in the production of electronic parts and the like, but it is unlikely that the specific surface area will increase due to this crushing. It is more important that the nickel oxide fine powder itself has a large specific surface area.

  Furthermore, in the method for producing nickel oxide fine powder according to the present invention, since nickel hydroxide produced by a wet method is heat-treated, a large amount of harmful SOx is not generated. Therefore, since expensive equipment for removing this is unnecessary, the manufacturing cost can be kept low.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by these Examples. In addition, the analysis of chlorine quality in Examples and Comparative Examples was performed by dissolving nickel oxide fine powder in nitric acid under microwave irradiation in a sealed container capable of suppressing the volatilization of chlorine, adding silver nitrate to precipitate silver chloride, Chlorine in the resulting precipitate was evaluated by a calibration curve method using a fluorescent X-ray quantitative analyzer (Magnix manufactured by PANalytical). In addition, the analysis of sulfur quality was performed with an ICP emission spectroscopic analyzer (SEP SPS-3000) after dissolving in nitric acid. The analysis of sodium quality was performed by dissolving in nitric acid and then evaluating with an atomic absorption device (Z-2300 manufactured by Hitachi High-Tech).

  The particle size of the nickel oxide fine powder was measured by a laser scattering method, and the particle size D90 with a volume integration of 90% was determined from the particle size distribution. The specific surface area was analyzed by the BET method using nitrogen gas adsorption.

[Example 1]
First, 2 L of sodium hydroxide aqueous solution adjusted to pH 8.5 consisting of pure water and sodium hydroxide was prepared in a 2 L reaction tank having a baffle plate and an overflow port. Next, a nickel aqueous solution prepared by dissolving nickel sulfate in pure water to have a nickel concentration of 120 g / L was prepared. Moreover, 12.5 mass% sodium hydroxide aqueous solution was prepared. These nickel aqueous solution and sodium hydroxide aqueous solution are continuously added to the sodium hydroxide aqueous solution in the above-mentioned reaction tank while adjusting the fluctuation range to be within 0.2 in terms of absolute value around pH 8.5. Mixed.

  In this way, a nickel hydroxide precipitate was continuously produced and recovered by overflow. The nickel aqueous solution was added at a rate of 5 mL / min, and the residence time of nickel hydroxide was adjusted to about 3 hours. Moreover, liquid temperature was 60 degreeC and it stirred at 700 rpm with the stirring blade.

  Filtration and 30-minute pure water repulping were repeated 10 times for the slurry recovered by overflow to obtain a nickel hydroxide filter cake. This filter cake was dried in the air at 110 ° C. for 24 hours using a blow dryer to obtain nickel hydroxide (step A). The obtained nickel hydroxide (500 g) was supplied to an atmospheric baking furnace and heat-treated at 865 ° C. for 2 hours to obtain nickel oxide (step B). Next, 300 g fractioned from the obtained nickel oxide was pulverized with a nano grinding mill (manufactured by Deoksugaku Kosakusho) at a pusher nozzle pressure of 1.0 MPa and a grinding pressure of 0.9 MPa (step C).

The obtained nickel oxide fine powder had a sulfur quality of 370 mass ppm, a chlorine quality of less than 50 mass ppm, and a sodium quality of less than 100 mass ppm. The specific surface area was 6.3 m ² / g, and D90 was 0.28 μm.

[Example 2]
Nickel oxide fine powder was obtained and analyzed in the same manner as in Example 1 except that the heat treatment temperature in Step B was 875 ° C.

The obtained nickel oxide fine powder had a sulfur quality of 250 mass ppm, a chlorine quality of less than 50 mass ppm, and a sodium quality of less than 100 mass ppm. The specific surface area was 5.1 m ² / g, and D90 was 0.42 μm.

[Example 3]
A nickel oxide fine powder was obtained and analyzed in the same manner as in Example 1 except that the heat treatment temperature in Step B was 900 ° C.

The obtained nickel oxide fine powder had a sulfur quality of 140 mass ppm, a chlorine quality of less than 50 mass ppm, and a sodium quality of less than 100 mass ppm. The specific surface area was 4.3 m ² / g, and D90 was 0.42 μm.

[Example 4]
A nickel oxide fine powder was obtained and analyzed in the same manner as in Example 1 except that the heat treatment temperature in Step B was 910 ° C.

The obtained nickel oxide fine powder had a sulfur quality of 99 mass ppm, a chlorine quality of less than 50 mass ppm, and a sodium quality of less than 100 mass ppm. The specific surface area was 4.1 m ² / g, and D90 was 0.58 μm.

[Example 5]
A nickel oxide fine powder was obtained and analyzed in the same manner as in Example 1 except that the heat treatment temperature in Step B was 920 ° C.

The obtained nickel oxide fine powder had a sulfur quality of less than 71 mass ppm, a chlorine quality of less than 50 mass ppm, and a sodium quality of less than 100 mass ppm. The specific surface area was 3.8 m ² / g, and D90 was 0.60 μm.

[Example 6]
A nickel oxide fine powder was obtained and analyzed in the same manner as in Example 1 except that the heat treatment temperature in Step B was 950 ° C.

The obtained nickel oxide fine powder had a sulfur quality of 42 mass ppm, a chlorine quality of less than 50 mass ppm, and a sodium quality of less than 100 mass ppm. The specific surface area was 3.2 m ² / g, and D90 was 0.85 μm.

[Example 7]
A nickel oxide fine powder was obtained and analyzed in the same manner as in Example 1 except that the heat treatment temperature in Step B was 1000 ° C.

The obtained nickel oxide fine powder had a sulfur quality of less than 50 mass ppm, a chlorine quality of less than 50 mass ppm, and a sodium quality of less than 100 mass ppm. The specific surface area was 3.4 m ² / g, and D90 was 0.95 μm.

[Example 8]
A nickel oxide fine powder was obtained and analyzed in the same manner as in Example 1 except that the heat treatment temperature in Step B was 1000 ° C. and the heat treatment time was 6 hours.

The obtained nickel oxide fine powder had a sulfur quality of less than 50 mass ppm, a chlorine quality of less than 50 mass ppm, and a sodium quality of less than 100 mass ppm. The specific surface area was 4.3 m ² / g, and D90 was 1.34 μm.

[Example 9]
A nickel oxide fine powder was obtained and analyzed in the same manner as in Example 1 except that the heat treatment temperature in Step B was 1050 ° C.

The obtained nickel oxide fine powder had a sulfur quality of less than 50 mass ppm, a chlorine quality of less than 50 mass ppm, and a sodium quality of less than 100 mass ppm. The specific surface area was 2.5 m ² / g, and D90 was 1.51 μm.

[Comparative Example 1]
A nickel oxide fine powder was obtained and analyzed in the same manner as in Example 1 except that the heat treatment temperature in Step B was 850 ° C.

The obtained nickel oxide fine powder had a sulfur quality of 670 mass ppm, a chlorine quality of less than 50 mass ppm, and a sodium quality of less than 100 mass ppm. The specific surface area was 7.0 m ² / g and D90 was 0.37 μm.

[Comparative Example 2]
A nickel oxide fine powder was obtained and analyzed in the same manner as in Example 1 except that the heat treatment temperature in Step B was 1200 ° C.

The obtained nickel oxide fine powder had a sulfur quality of less than 50 mass ppm, a chlorine quality of less than 50 mass ppm, and a sodium quality of less than 100 mass ppm. The specific surface area was 1.8 m ² / g, and D90 was 3.10 μm.

[Comparative Example 3]
A nickel oxide fine powder was obtained and analyzed in the same manner as in Example 1 except that nickel chloride was used in place of nickel sulfate in step A and the heat treatment temperature in step B was 750 ° C.

The obtained nickel oxide fine powder had a sulfur quality of less than 50 mass ppm, a chlorine quality of 240 mass ppm, and a sodium quality of less than 100 mass ppm. The specific surface area was 3.3 m ² / g, and D90 was 0.72 μm.

[Comparative Example 4]
A nickel oxide fine powder was obtained and analyzed in the same manner as in Example 1 except that nickel chloride was used instead of nickel sulfate in step A and the heat treatment temperature in step B was 900 ° C.

The obtained nickel oxide fine powder had a sulfur quality of less than 50 mass ppm, a chlorine quality of 120 mass ppm, and a sodium quality of less than 100 mass ppm. The specific surface area was 2.2 m ² / g, and D90 was 1.00 μm.

[Comparative Example 5]
A nickel oxide fine powder was obtained and analyzed in the same manner as in Example 1 except that nickel chloride was used in place of nickel sulfate in step A and the heat treatment temperature in step B was 950 ° C.

The obtained nickel oxide fine powder had a sulfur quality of less than 50 mass ppm, a chlorine quality of less than 50 mass ppm, and a sodium quality of less than 100 mass ppm. The specific surface area was 1.7 m ² / g, and D90 was 1.98 μm.

About the said Examples 1-9 and Comparative Examples 1-5, a raw material, heat processing conditions (roasting temperature and roasting time), sulfur quality of the obtained nickel oxide fine powder, chlorine quality, sodium quality, specific surface area, and D90 Are summarized in Table 1 below.

As can be seen from the results in Table 1 above, in all examples, the sulfur quality is controlled to 400 mass ppm or less, the chlorine quality is less than 50 mass ppm, and the sodium quality is less than 100 mass ppm. . Moreover, the specific surface area is as large as 2.0 m ² / g or more, and it can be seen that fine nickel oxide fine powder is obtained.

  On the other hand, in Comparative Examples 1 to 5, the heat treatment temperature deviates from the requirements of the present invention, or nickel chloride was used as the raw material nickel salt, so any of sulfur grade, chlorine grade, specific surface area value, or D90 However, it is not within a range suitable as an electronic component material.

Claims (5)

  Step A to obtain nickel hydroxide by neutralizing an aqueous nickel sulfate solution with alkali, and heat treating the obtained nickel hydroxide in a non-reducing atmosphere at a temperature higher than 850 ° C. and lower than 1200 ° C. to form nickel oxide particles And a step C of crushing a sintered body of nickel oxide particles that can be formed during the heat treatment.   2. The method for producing fine nickel oxide powder according to claim 1, wherein the nickel concentration in the nickel sulfate aqueous solution in the step A is 50 to 180 g / L.   The method for producing fine nickel oxide powder according to claim 1 or 2, wherein the crushing in the step C is performed by causing the nickel oxide particles to collide with each other. Nickel oxide fine powder obtained by the production method according to claim 1, having a specific surface area of ² to 7 m ² / g, a sulfur quality of 400 mass ppm or less, a chlorine quality of 50 mass ppm or less, sodium Nickel oxide fine powder characterized by having a quality of 100 mass ppm or less.   The nickel oxide fine powder according to claim 4, wherein D90 measured by a laser scattering method is 3 μm or less.