JP2013040067A - Nickel oxide powder, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fine nickel oxide powder suitable as an electronic part material and having a low chlorine concentration, and an industrially stable method for manufacturing the same.SOLUTION: A nickel hydroxide is heat treated which contains 100 to 3,000 ppm of an oxo-acid (formula: EO(OH)) type anion different from an anion forming a nickel salt used to obtain the nickel hydroxide by neutralization, in a ratio of a center element (E) to the total of nickel in the nickel hydroxide in terms of nickel oxide and the center element (E). The chlorine concentration is ≤100 mass ppm; the content of the center element (E) is 100 to 3,000 mass ppm; and the specific surface area is ≥5.5 m/g.

Description

  The present invention relates to nickel oxide powder and a method for producing the same, and more specifically, impurity grade, in particular, chlorine grade is low, contains element (E) derived from oxo acid in a certain range, is fine, The present invention relates to a nickel oxide powder suitable as a component material 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, like a rotary furnace such as a rotary kiln, a continuous furnace such as a pusher furnace, or a burner furnace. It is manufactured by firing in an oxidizing atmosphere using a simple batch furnace. These nickel oxide powders are used in a variety of applications. For example, in applications as electronic component materials, they are mixed with other materials such as iron oxide and zinc oxide, and then sintered to form ferrite components. Is widely used.

  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 specific surface area may be used as an index for measuring that the powder is fine. 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-11-144934 (Patent Document 1) proposes a ferrite material containing 100 to 1000 ppm of chlorine component converted to Cl and / or 750 to 2000 ppm of sulfuric acid component converted to S in the raw material stage. Has been. This ferrite material is said to lower the calcining temperature, and as a result, ferrite powder can be produced economically.

  As described above, the nickel oxide powder used as an electronic component material, particularly as a raw material for ferrite components, not only reduces the content of impurities such as chlorine and sulfur, but also keeps the content of impurities within a predetermined range. Strict control is required.

  Conventionally, as a method for producing 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.

  However, the nickel oxide powder production method of Patent Document 5 suppresses coarsening, that is, magnesium, which is an element that inhibits sinterability, is mixed in the nickel oxide powder. Sinterability may not be obtained, and it was not necessarily suitable for electronic component materials. 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.

  As described above, the nickel oxide powder obtained by the conventional technique has a fine particle diameter, that is, a nickel oxide powder having a larger specific surface area and having impurities such as chlorine and sulfur controlled within a predetermined range. Was not enough, and further improvement was desired.

JP-A-11-144934 Japanese Patent Laid-Open No. 2001-032002 JP 2004-123488 A JP 2004-189530 A JP 2009-196870 A

  In view of the above problems, the present invention has a low impurity content, particularly a chlorine content, contains an oxoacid-derived element (E) in a certain range, and has a fine particle size, that is, a high specific surface area. An object of the present invention is to provide a nickel oxide powder suitable as an electronic component material and a method for producing the same.

In order to achieve the above object, the present inventor has focused on a method for producing nickel oxide fine powder by roasting nickel hydroxide obtained by neutralizing an aqueous nickel salt solution that does not generate a large amount of harmful gas during heat treatment. As a result of extensive research, the nickel hydroxide obtained by neutralization with alkali contains a predetermined amount of an anion of oxo acid (general formula: EO _m (OH) _n ) type, and is heat-treated. The inventors have found that a fine nickel oxide powder whose impurity content is controlled within a predetermined range can be obtained, and has completed the present invention.

That is, the method for producing nickel oxide fine powder provided by the present invention comprises a crystallization step of obtaining nickel hydroxide by neutralizing an aqueous nickel salt solution to pH 8.3 to 9.0 with an alkali, and the obtained nickel hydroxide. And a heat treatment step of obtaining nickel oxide by heat-treating the washed nickel hydroxide at a temperature exceeding 700 ° C. and less than 950 ° C. in a non-reducing atmosphere. There,
In the heat treatment step, an oxo acid (general formula: EO _m (OH) _n ) type anion different from the anion forming the nickel salt is converted into a mass and a center obtained by converting nickel in nickel hydroxide into nickel oxide. Nickel hydroxide containing 100 to 3000 mass ppm in a ratio of the central element (E) to the total of the elements (E) is heat-treated.

In the crystallization step, an oxo acid (general formula: EO _m (OH) _n ) different from the anion forming the nickel salt contained in the reaction solution is added to the oxo acid (general formula: EO _m). (OH) _n ) is preferably added in an amount of 100 to 3000 ppm by mass in terms of the ratio of the central element (E) to the total of the central element (E) and the mass of nickel in the reaction solution converted to nickel oxide.

In the washing step, oxo acid (general formula: EO _m (OH) _n ) different from the anion forming the nickel salt used in the crystallization step is oxidized with nickel in the nickel hydroxide to be washed. It is preferable to wash with a cleaning liquid containing 100 to 3000 ppm by mass in terms of the ratio of the central element (E) to the total of the mass converted to nickel and the central element (E).

  The oxo acid is preferably at least one selected from carbonic acid, silicic acid, nitric acid, and phosphoric acid.

  Furthermore, the nickel concentration of the nickel chloride aqueous solution is preferably 50 to 130 g / L, and the alkali used in the crystallization step is preferably sodium hydroxide and / or potassium hydroxide.

The nickel oxide fine powder provided by the present invention has a specific surface area of 5.5 m ² / g or more, a D90 measured by a laser scattering method of 1 μm or less, a chlorine content of 100 mass ppm or less, an oxoacid (general The content of the central element (E) forming the formula: EO _m (OH) _n ) is 100 to 3000 ppm by mass.

  According to the present invention, a nickel oxide powder that has a small content of impurities such as chlorine and sulfur, contains a predetermined amount of an element (E) derived from oxo acid, is fine, and is suitable as an electronic component material such as a ferrite component. Can be obtained. In addition, the manufacturing method does not generate a large amount of chlorine or SOx gas, is easy and has high productivity, and can be industrially mass-produced stably. Therefore, its industrial value is extremely large.

In the method for producing nickel oxide powder of the present invention, an anion of an oxo acid (general formula: EO _m (OH) _n ) type different from the anion forming the nickel salt used in the crystallization step is converted into nickel hydroxide. It is important to heat-treat nickel hydroxide containing 100 to 3000 mass ppm in terms of the ratio of the central element (E) to the total of the central element (E) and the mass converted from nickel to nickel oxide.

  The nickel hydroxide contains the oxoacid-type anions as residual ions, which controls the direction of crystal growth by sintering the nickel oxide particles produced in the subsequent heat treatment step, resulting in a fine and high ratio. A nickel oxide powder having a surface area can be obtained.

  Although the detailed reason why the oxo acid type anion controls the crystal growth is unknown, the coordination of the oxo acid type anion to nickel hydroxide (complex) is bonded as a cis structure and oxidized in the heat treatment step. It is considered that the crystal growth direction is controlled by inhibiting the coarsening of the crystal in the C-axis direction of nickel. By suppressing the coarsening of the nickel oxide particles in such heat treatment, it is possible to obtain a nickel oxide powder that is fine as a result and suitable for an electronic material having a high specific surface area without impairing other characteristics.

  On the other hand, for example, nickel hydroxide crystallized from nickel chloride tends to produce fine, low-chlorine nickel oxide from a relatively low temperature in the heat treatment step, so that the heat treatment temperature can be increased by containing an oxo acid type anion. Thus, chlorine can be sufficiently reduced. In addition, when sodium hydroxide is used as the alkali, readily water-soluble NaCl is produced by neutralization, so that the residual Na compound that inhibits sintering in nickel hydroxide can be reduced.

  Thus, by including an oxo acid type anion in the nickel hydroxide in the crystallization step, it is possible to suppress the coarsening of the nickel oxide particles during the heat treatment, and at the same time, the impurities in the resulting nickel oxide The content can be reduced.

  When the central element (E) derived from the oxo acid is less than 100 ppm by mass with respect to the total of the mass obtained by converting nickel in nickel hydroxide into nickel oxide and the central element (E), the crystal growth direction in the heat treatment step is sufficiently I can't control it. On the other hand, even if added in excess of 3000 ppm by mass, the effect of refining nickel oxide does not increase. On the other hand, when the obtained nickel oxide is used as a material for an electronic component, the characteristics of the electronic component may be impaired.

The oxo acid is represented by the structure of the general formula: EO _m (OH) _n ), and may be either inorganic or organic, and the central element (E) may be a metal or a nonmetal. Furthermore, any form such as a salt obtained by neutralization with sodium hydroxide and / or potassium hydroxide may be used. Examples of oxo acids include boric acid (BO3), carbonic acid (CO3), carboxylic acid (COOH), silicic acid (SiO3), nitrous acid (NO2), nitric acid (NO3), phosphorous acid (PO3), phosphoric acid (PO4), It is preferably at least one selected from sulfurous acid (SO3), sulfuric acid (SO4), sulfonic acid, sulfinic acid, chromic acid, dichromic acid, and permanganic acid. Carbonic acid (CO3), silicic acid (SiO3), nitric acid More preferably, it is at least one selected from (NO3) and phosphoric acid (PO4). Particularly preferred are oxo acids containing silicic acid (SiO 3).

  As a method for adding oxo acid to the nickel hydroxide, a predetermined amount of oxo acid is used in the reaction solution in the crystallization step, in the washing solution in the washing step, or both using an oxo acid such as silicic acid. What is necessary is just to add an acid.

The method of adding an oxo acid to the reaction solution is a method of adding an oxo acid (general formula: EO _m (OH) _n ) different from the anion forming the nickel salt contained in the reaction solution to the nickel in the reaction solution. 100 to 3000 mass ppm is added in the ratio of the central element (E) to the total of the mass converted to nickel oxide and the central element (E).

In the addition of oxo acid to the reaction solution, neutralization reaction with alkali yields an oxo acid salt (general formula: EO _m (OM) _n ), almost all of which co-precipitates with nickel hydroxide, together with nickel hydroxide. Crystallized and precipitated. Here, when sodium hydroxide and / or potassium hydroxide is used as the alkali, M = Na and / or K.

  Therefore, in addition of oxo acid to the reaction solution, nickel hydroxide can contain a predetermined amount of an oxo acid type anion by adding 100 to 3000 mass ppm to the reaction solution. Depending on the crystallization conditions, the amount of oxoacid anion contained in nickel hydroxide may be slightly less than the amount added, but the amount of decrease can be determined by preliminary tests, etc. The content of can be easily controlled. Although the central element (E) depends on the element, the amount of decrease due to volatilization in the subsequent heat treatment step is small, and the content of the central element (E) in the nickel oxide powder is similarly determined by a preliminary test or the like. It is possible to control. In order to include a predetermined amount of the central element (E) in the final nickel oxide powder only by adding the oxo acid to the reaction solution, the addition of the oxo acid to the reaction solution is carried out at a ratio of 200 to It is preferable to add 3000 ppm by mass.

On the other hand, the method of adding oxo acid to the washing liquid in the washing step is different from the anion forming the nickel salt used in the crystallization step after washing the nickel hydroxide recovered from the crystallization step with water or the like. Oxonic acid (general formula: EO _m (OH) _n ) 100 to 3000 in terms of the ratio of the central element (E) to the total of the central element (E) and the total mass of the central element (E) when nickel in the nickel hydroxide to be added is converted to nickel oxide The cleaning is performed with a cleaning solution containing ppm of oxo acid (general formula: EO _m (OH) _n ).

  As the cleaning solution, water to which oxo acid is added can be used, but it is preferable that an alkali be present in the cleaning solution. By coexisting with an alkali, the oxo acid salt is formed and adheres to the surface of the nickel hydroxide particles, so that the oxo acid type anion can be efficiently added. The amount of oxo acid anion adhering to the surface of nickel hydroxide particles at the time of washing tends to decrease more than the method added at the time of crystallization. Thus, the content of the oxo acid type anion can be easily controlled. In order to contain a predetermined amount of the central element (E) in the final nickel oxide powder only by adding the oxo acid to the cleaning liquid, the addition of the oxo acid to the cleaning liquid is 300 to 3000 mass in the above ratio. It is preferable to add ppm.

  Further, by coexisting alkali, a chlorine cleaning effect of re-dissolving chlorine from nickel hydroxide can be expected. Further, the cleaning effect can be further enhanced by heating the cleaning liquid. Although the clear reason why the chlorine cleaning effect is enhanced by heating is unknown, the water of crystallization in nickel hydroxide is released during the heating treatment in an alkaline aqueous solution, so that the crystal structure is involved when the crystal structure changes. It is thought to release chlorine. When heating, it is preferable to heat to 30 ° C. or higher, preferably 40 to 60 ° C.

  As the alkali, sodium hydroxide, potassium hydroxide and the like are preferable in consideration of impurities remaining in nickel, and sodium hydroxide is more preferable in consideration of cost.

  The concentration of the alkali in the cleaning solution is not particularly limited, but is preferably in the range of 0.01 to 0.5 mol in order to sufficiently discharge the impurities due to the re-dissolution of the chlorine and the phase change of the nickel hydroxide. A range of 0.05 to 0.2 mol is more preferable. For example, when the concentration of the sodium hydroxide aqueous solution is 0.01 mol, the above effect may not be obtained sufficiently. is there.

  After washing or heating with the above washing solution, washing with water is preferable for reducing impurities.

Next, the method for producing nickel oxide of the present invention will be described in detail for each step.
The crystallization step is a step of obtaining nickel hydroxide by neutralizing an aqueous nickel salt solution to pH 8.3 to 9.0 with an alkali. Although the nickel salt used as a raw material is not specifically limited, Since the obtained nickel oxide fine powder is used for electronic components, it is desirable that the impurity contained in the raw material is less than 100 mass ppm.

  In addition, at least one selected from the above-mentioned nickel salts, nickel chloride, and nickel sulfate can be used. To facilitate control of the oxo acid content in nickel hydroxide, nickel chloride that does not contain oxo acid is used. It is preferable to use it. In addition, when nickel sulfate is used, in order to improve the crystallinity of nickel oxide, the nickel oxide in nickel hydroxide is converted into nickel oxide by washing thoroughly in the subsequent washing step. The ratio of the central element (E) to the total of the elements (E) is preferably 1000 to 3000 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, it is effective to add a nickel salt aqueous solution and an alkaline aqueous solution to a solution that is sufficiently stirred in the reaction vessel by a double jet method. 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 8.3 to 9.0, and the pH is particularly preferably within this range. When the pH is lower than 8.3, when nickel chloride is used, chlorine ions remaining in the nickel hydroxide increase, and these heat-treat the furnace body as a large amount of hydrochloric acid during heat treatment. Therefore, it is not preferable. Moreover, when pH becomes higher than 9.0, the nickel hydroxide obtained will become too fine and filtration may become difficult. Moreover, sintering may progress too much in the heat treatment process performed later, and it may become difficult to obtain fine nickel oxide powder.

  The pH during the neutralization reaction is preferably controlled so that the fluctuation range is within ± 0.2 from the set value within the range of 8.3 to 9.0. If the fluctuation width of the pH is larger than this, the increase of impurities and the particle diameter of the nickel oxide powder are increased, which may cause a reduction in specific surface area. When the pH is lower than pH 8.3, which is the neutralization condition, a slight nickel component may remain in the aqueous solution. In this case, the pH is increased to about 10 after neutralization crystallization, and the nickel in the filtrate is increased. Is preferably reduced.

  Moreover, in the said nickel salt aqueous solution, although nickel salt concentration is not specifically limited, The range of 50-130 g / L is preferable as nickel concentration. When the nickel concentration is less than 50 g / L, the productivity in the crystallization process is deteriorated, and when it exceeds 130 g / L, the anion concentration in the aqueous solution is increased, and the content of chlorine and oxo acid in the produced nickel hydroxide is high. Therefore, the content of the central element (E) of chlorine and oxo acid in the finally obtained nickel oxide powder may not be sufficiently reduced.

  The liquid temperature during the neutralization reaction can be carried out at room temperature under normal conditions without any particular problems, but is preferably in the range of 50 to 70 ° C. in order to sufficiently grow nickel hydroxide particles. . By sufficiently growing the nickel hydroxide particles, it is possible to suppress the inclusion of impurities such as chlorine, sulfur and sodium into the nickel hydroxide, and finally reduce the impurities in the nickel oxide powder. When the liquid temperature is less than 50 ° C., the nickel hydroxide particles are not sufficiently grown, and impurities are likely to be involved in the nickel hydroxide. On the other hand, when the liquid temperature exceeds 70 ° C., the evaporation of water becomes intense and the concentration of impurities in the aqueous solution increases, so that the impurity content in the produced nickel hydroxide may increase.

  After completion of the neutralization reaction, the precipitated nickel hydroxide is collected by filtration. The collected filter cake is washed before the next heat treatment step. When impurities such as chlorine ions are not sufficiently reduced by one cleaning, it is preferable to perform cleaning a plurality of times. Further, when nickel sulfate is used as the nickel salt, it is preferable to sufficiently wash so that the sulfate ion becomes a predetermined amount.

  The amount of the cleaning solution with respect to nickel hydroxide is not particularly limited and may be an amount that can sufficiently reduce residual chlorine. However, in order to disperse nickel hydroxide well, the mixing ratio of nickel hydroxide / cleaning solution Is preferably 80 to 150 g / L, and more preferably 90 to 110 g / L. Further, the treatment time is not particularly limited, and may be a washing time in which the residual chlorine concentration is sufficiently reduced depending on the treatment conditions. By setting the treatment conditions so that residual chlorine can be sufficiently reduced, the effect of refining nickel oxide can be sufficiently obtained.

  The washing method is not particularly limited. In addition to repulp washing by mixing and stirring with a washing liquid by a mixer or the like, washing filtration by a filter press that allows the washing liquid to pass through the filtrate and dissolve and remove the salt is also effective. . In the cleaning with water, it is preferable to use pure water that does not have the possibility of mixing impurities. Examples of the apparatus used for cleaning include a normal wet reaction tank and a filter press. Moreover, when wash | cleaning by heating a washing | cleaning liquid to 30 degreeC or more, the normal wet reaction tank which can be heated can be used. In the cleaning using a wet reaction tank, it is preferable to stir the slurry containing nickel hydroxide during the cleaning, and for example, ultrasonic stirring or mechanical stirring can be used.

  The nickel hydroxide after washing is recovered by filtration. The water content of the filter cake is preferably 10 to 40% by mass, and more preferably 25 to 35% by mass. When the water content is less than 10% by mass, the filter cake is difficult to uniformly disperse in the cleaning liquid when further washing is performed, so that the efficiency of the washing process is deteriorated, and the water content of the filter cake is lowered, so that severe dehydration treatment is performed This is not preferable because it is necessary. When the water content is higher than 40% by mass, the handling property of nickel hydroxide is poor, and the uniform processing may be hindered, and the processing amount necessary to obtain a certain amount of nickel hydroxide increases. There are inconveniences such as.

  The heat treatment step is a step of heat-treating the nickel hydroxide after washing into nickel oxide. By this heat treatment, the hydroxyl groups in the nickel hydroxide crystal are eliminated and nickel oxide particles are formed. By appropriately setting the heat treatment temperature, the particle size can be refined and the impurity content can be controlled. In addition, many portions of chlorine remaining after the washing treatment can be volatilized.

  The heat treatment of nickel hydroxide is performed at a temperature exceeding 700 ° C. and less than 950 ° C. in a non-reducing atmosphere. The heat treatment temperature is more preferably 750 to 900 ° C., and further within the range of 800 to 900 ° C. preferable. When the heat treatment temperature is 700 ° C. or lower, residual chlorine and impurities are not sufficiently volatilized, and the contents of chlorine and impurities in nickel oxide cannot be sufficiently reduced. The primary particles of nickel hydroxide are plate-like, and the primary particles are spheroidized as nickel oxide is produced. However, the spheroidization does not proceed at 700 ° C. or lower, and the nickel oxide is not sufficiently refined. On the other hand, if it becomes 950 degreeC or more, sintering of nickel oxide particles will become remarkable, a specific surface area will become small, or mechanical crushing will be needed. As the sintering further proceeds, it becomes difficult to obtain a necessary specific surface area even by mechanical crushing.

The heat treatment time can be appropriately set according to the treatment temperature and the treatment amount, but may be set so that the specific surface area of the finally obtained nickel oxide powder is 5.5 m ² / g or more. When nickel oxide is crushed after the heat treatment step, the specific surface area of the nickel oxide powder obtained is about 0.5 m ² / g higher than the specific surface area of the nickel oxide after heat treatment. Judgment and necessity of crushing can be set based on the specific surface area of the nickel powder.

  The atmosphere for the heat treatment is not particularly limited as long as it is a non-reducing atmosphere, but is preferably an air atmosphere in consideration of economy. Moreover, in order to discharge | emit the water vapor | steam generated by the detachment | desorption of a hydroxyl group in the case of heat processing, it is preferable to carry out in the air flow with sufficient flow velocity. A general roasting furnace can be used for the heat treatment.

A step of mechanically crushing the obtained nickel oxide powder can be added after the heat treatment step. Although the specific surface area increased by crushing is as small as about 0.5 m ² / g as described above, it can be expected that a material more suitable as an electronic material or the like can be expected by loosening the aggregation by crushing. It is also presumed that when the hydroxyl group in the nickel hydroxide crystal is released into nickel oxide in the heat treatment step, the oxo acid type anion and nickel complex are bonded to the cis type to promote the refinement of the particle size. However, when heat treatment is performed at a high temperature for removing impurities, the sintering of nickel oxide particles may proceed.

  In such a case, it is possible to destroy the sintered portion by crushing to make the nickel oxide particles finer, and to sufficiently increase the specific surface area of the nickel oxide powder. In the production method of the present invention, the nickel oxide particles obtained by the heat treatment are sufficiently fine and the degree of sintering between the particles is small, so that a sufficiently fine nickel oxide powder can be obtained without applying a large crushing force. be able to.

  Nickel oxide powder can be crushed by mechanical crushing using a mortar, etc., especially those using crushing media such as bead mills and ball mills on an industrial scale, and those that do not use crushing media such as jet mills. Although a general method can be used, it is preferable to perform crushing without using a crushing medium in order to prevent components constituting the crushing media such as zirconia from being mixed as impurities. Although the crushing itself becomes easy when using the crushing media, there is a possibility that components constituting the crushing media such as zirconia are mixed as impurities.

  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 powder cannot be obtained, which is not preferable. 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 medium, there are a method of causing powders to collide with each other, a method of applying a shearing force to the powder with a medium such as a liquid, and the like. Examples of the crushing apparatus using the former include a jet mill and an optimizer (registered trademark). Moreover, as a crushing apparatus using the latter, Nanomizer (trademark) etc. are mentioned, for example. Among these crushing methods, a method of causing powders to collide with each other is particularly preferable because there is little fear of mixing impurities and a relatively large crushing force can be obtained. The crushing conditions are not particularly limited, and nickel oxide powder having a desired particle size distribution can be easily obtained by adjustment within the range of normal conditions. Thereby, the nickel oxide 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 has a low chlorine content and contains a predetermined amount of an oxoacid-derived element E (mainly Si, S, C, N, B, P, etc.), Since the specific surface area is also large, it is suitable as a material for electronic parts. Specifically, the residual chlorine content is 100 ppm by mass or less, the central element (E) forming the oxo acid (general formula: EO _m (OH) _n ) is 100 to 3000 ppm by mass, and the specific surface area Is 5.5 m ² / g or more, and D90 (particle diameter at 90% volumetric integration of the particle amount in the particle size distribution curve) measured by a laser scattering method is 1 μm or less. In particular, when sulfur is added as the central element (E), it is preferably contained in an amount of 1000 to 3000 mass ppm in order to improve the sinterability by improving the crystallinity of nickel oxide.

  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 also not included, so that the zirconia quality and Group 2 element content can be reduced to 30 ppm by mass or less.

  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). The analysis of the oxo acid central element (E) was carried out with an ICP emission spectroscopic analyzer (SPS-3000 manufactured by Seiko) after dissolving in nitric acid.

  The particle size of the nickel oxide 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]
In a 3 L beaker, 500 mL of an aqueous sodium hydroxide solution adjusted to pH 8.5 consisting of pure water and sodium hydroxide was prepared. First, sodium silicate (oxo acid salt: SiO (ONa) ₂ ) is added to this aqueous solution, and the silicon content with respect to the sum of the mass of silicon converted to nickel oxide and the mass of silicon is 1200 mass ppm. Then, 1 L of a nickel chloride aqueous solution having a nickel concentration of 120 g / L and a 12.5 mass% sodium hydroxide aqueous solution were added at pH 8.5 so that the fluctuation range was within 0.2 in absolute value. The mixture was continuously added and mixed while adjusting the temperature to produce a nickel hydroxide precipitate.

  At that time, the nickel chloride aqueous solution was added at a rate of 6 mL / min. The liquid temperature was 60 ° C., and the mixture was stirred at 200 rpm with a stirring blade. After adding the nickel chloride aqueous solution, the mixture was aged for 3 hours while continuing stirring (crystallization step).

  Thereafter, filtration and repulp washing with pure water stirred for 30 minutes were repeated four times to obtain a nickel hydroxide filter cake (washing step). This filter cake was dried in the air at 110 ° C. for 24 hours using a blow dryer to obtain nickel hydroxide.

  10 g of the obtained nickel hydroxide was supplied to an atmospheric firing furnace and heat-treated at 800 ° C. for 3 hours to obtain nickel oxide (heat treatment step). The nickel oxide after the heat treatment was crushed in a mortar to obtain nickel oxide powder.

The obtained nickel oxide powder had a chlorine content of 40 mass ppm and a silicon content of 1100 mass ppm. The specific surface area was 7.2 m ² / g, and D90 was 0.77 μm.

  Subsequently, the following Examples 2 to 10 and Comparative Examples 1 to 7 were carried out, but only conditions different from those of Example 1 were described. Moreover, about Examples 1-10 and Comparative Examples 1-7, the kind of alkali used for neutralization, the nickel salt concentration, the pH during neutralization, the kind and amount of oxo acid added in each step, and the heat treatment temperature Table 1 below collectively shows the oxo acid central element (E) content, specific surface area, chlorine content, and D90 of the obtained nickel oxide powder in Table 2 below.

[Example 2]
In the washing process, filtration and repulp washing with pure water were repeated three times, and then in the fourth repulp washing, sodium silicate was converted to nickel oxide in nickel hydroxide with respect to the total mass of silicon and silicon. A nickel oxide powder was obtained and analyzed in the same manner as in Example 1 except that it was washed with an aqueous solution of sodium hydroxide having a pH of 9.0 containing 1600 mass ppm and filtered.

[Example 3]
In the crystallization step, the solution was neutralized with an aqueous sodium hydroxide solution not containing sodium silicate. In the washing step, filtration and repulp washing with pure water were repeated three times. The same procedure as in Example 1 was performed except that the nickel hydroxide in nickel hydroxide was washed with a sodium hydroxide aqueous solution having a pH of 9.0 containing 2200 mass ppm with respect to the total mass of nickel converted to nickel oxide and filtered. Nickel oxide powder was obtained and analyzed.

[Example 4]
In the crystallization step, nickel oxide powder was obtained and analyzed in the same manner as in Example 1 except that 2900 mass ppm of sodium silicate was added.

[Example 5]
In the crystallization step, nickel oxide powder was obtained and analyzed in the same manner as in Example 1 except that 300 mass ppm of sodium silicate was added.

[Example 6]
In the heat treatment step, nickel oxide powder was obtained and analyzed in the same manner as in Example 1 except that the heat treatment condition was 700 ° C. for 3 hours.

[Example 7]
In the heat treatment step, nickel oxide powder was obtained and analyzed in the same manner as in Example 1 except that the heat treatment condition was 950 ° C. for 3 hours.

[Example 8]
In the crystallization step, nickel oxide powder was obtained and analyzed in the same manner as in Example 1 except that the pH was adjusted to 9.0 using potassium hydroxide.

[Example 9]
In the crystallization process, 10 L of a sodium hydroxide aqueous solution adjusted to pH 8.5 using a 100 L SUS reaction tank was prepared, and 20 L of a nickel chloride aqueous solution having a nickel concentration of 50 g / L was added at a rate of 120 mL / min. Except for the above, nickel oxide powder was obtained and analyzed in the same manner as in Example 1.

[Example 10]
In the crystallization step, nickel oxide powder was obtained and analyzed in the same manner as in Example 1 except that an 80 g / L nickel sulfate solution was used instead of the 120 g / L nickel chloride solution as the nickel salt solution.

[Comparative Example 1]
In the crystallization step, nickel oxide powder was obtained and analyzed in the same manner as in Example 1 except that sodium silicate was not added.

[Comparative Example 2]
In the crystallization step, nickel oxide powder was obtained and analyzed in the same manner as in Example 1 except that 6000 mass ppm of sodium silicate was added.

[Comparative Example 3]
In the heat treatment step, nickel oxide powder was obtained and analyzed in the same manner as in Example 1 except that the heat treatment condition was set at 600 ° C. for 3 hours.

[Comparative Example 4]
In the heat treatment step, nickel oxide powder was obtained and analyzed in the same manner as in Example 1 except that the heat treatment condition was 980 ° C. for 3 hours.

[Comparative Example 5]
In the crystallization step, nickel oxide powder was obtained and analyzed in the same manner as in Example 1 except that the pH was adjusted to 8.0. In the crystallization process, crystallization of nickel hydroxide hardly occurred.

[Comparative Example 6]
Nickel oxide powder was obtained and analyzed in the same manner as in Example 1 except that the pH was adjusted to 10 in the crystallization step.

[Comparative Example 7]
In the crystallization step, the same procedure as in Example 1 was performed except that an 80 g / L nickel sulfate solution was used as the nickel salt solution instead of the 120 g / L nickel chloride solution and no sodium silicate was added. Nickel oxide powder was obtained and analyzed.

As can be seen from the results of Table 2 above, in all Examples, the chlorine quality is 100 ppm by mass or less, and the central element (E) derived from oxo acid is in the range of 100 to 3,000 ppm by mass. It is controlled. Furthermore, the specific surface area is as large as 5.5 m ² / g or more, and D90 measured by the laser scattering method is 1 μm or less, and a fine nickel oxide powder is obtained.

On the other hand, in Comparative Example 1, the specific surface area is small because no oxo acid is added. On the other hand, in Comparative Example 2, D90 is large although the specific surface area is small because the addition of oxo acid is too much. In Comparative Example 7, the specific surface area is small because only sulfate ions are contained as the oxo acid.
Furthermore, since the comparative example 3 has a low heat treatment temperature, the chlorine content greatly exceeds the preferred range. On the other hand, Comparative Example 4 has a low specific surface area because of the high heat treatment temperature. In Comparative Examples 5 and 6, since pH adjustment during crystallization was not appropriate, good nickel hydroxide was not obtained, and the specific surface area was small.

The nickel oxide powder of the present invention is suitable as an electronic component material such as a ferrite component because it has a small impurity content, particularly a chlorine content, and is fine.

Claims (7)

A crystallization step for obtaining nickel hydroxide by neutralizing an aqueous nickel salt solution to pH 8.3 to 9.0 with an alkali, a washing step for washing the obtained nickel hydroxide, and the washed nickel hydroxide is non-reducing A heat treatment step for obtaining nickel oxide by heat treatment at a temperature of 700 to 950 ° C. in an atmosphere,
In the heat treatment step, an oxo acid (general formula: EO _m (OH) _n ) type anion different from the anion forming the nickel salt is converted into a mass obtained by converting nickel in nickel hydroxide into nickel oxide. A method for producing nickel oxide powder, comprising heat-treating nickel hydroxide containing 100 to 3000 mass ppm in a ratio of the central element (E) to the total of the central elements (E). In the crystallization step, an oxo acid (general formula: EO _m (OH) _n ) different from the anion forming the nickel salt contained in the reaction solution is added to the reaction solution, and the nickel in the reaction solution is converted to nickel oxide. The method for producing nickel oxide powder according to claim 1, wherein 100 to 3000 ppm by mass is added in a ratio of the central element (E) to the total mass of the central element (E) converted to mass. In the washing step, an oxo acid (general formula: EO _m (OH) _n ) different from the anion forming the nickel salt used in the crystallization step is changed to nickel oxide in the nickel hydroxide to be washed. The method for producing nickel oxide powder according to claim 1, wherein the nickel oxide powder is washed with a washing solution containing 100 to 3000 ppm by mass in terms of the ratio of the central element (E) to the total of the converted mass and the central element (E).   The method for producing nickel oxide powder according to any one of claims 1 to 3, wherein the oxo acid is at least one selected from carbonic acid, silicic acid, nitric acid, and phosphoric acid.   The nickel concentration of said nickel chloride aqueous solution is 50-130 g / L, The manufacturing method of the nickel oxide powder in any one of Claims 1-4 characterized by the above-mentioned.   The method for producing nickel oxide powder according to any one of claims 1 to 4, wherein the alkali used in the crystallization step is sodium hydroxide and / or potassium hydroxide. Specific surface area is 5.5 m ² / g or more, D90 measured by laser scattering method is 1 μm or less, chlorine content is 100 mass ppm or less, and oxo acid (general formula: EO _m (OH) _n ) is formed. The nickel oxide powder characterized in that the content of the central element (E) is 100 to 3000 ppm by mass.