JP6241491B2 - Nickel oxide fine powder and method for producing the same, nickel hydroxide powder for use in the raw material for producing the nickel oxide fine powder, and method for producing the same - Google Patents

Description

  The present invention relates to nickel oxide fine powder and a method for producing the same, and more specifically, nickel hydroxide powder for nickel oxide fine powder production raw material, a method for producing the same, and nickel oxide fine powder using the nickel hydroxide powder. It relates to the manufacturing method.

  In general, the nickel oxide powder is a nickel salt such as nickel sulfate, nickel nitrate, nickel carbonate, nickel hydroxide, or a nickel metal powder. And manufactured by firing in an oxidizing atmosphere. 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.

  Like the above ferrite parts, when a composite metal oxide is produced by mixing and firing a plurality of materials, the production reaction is rate-determined by a solid phase diffusion reaction. As a raw material generally used, fine powder is used. This increases the probability of contact with other materials and increases the activity of the particles. Therefore, it is known that the reaction proceeds uniformly in a low-temperature and short-time baking treatment. Therefore, in such a method for producing a composite metal oxide, reducing the particle size of the raw material powder is an important factor for improving the production efficiency.

  In recent years, a solid oxide fuel cell is expected as a new power generation system from the viewpoint of both environment and energy, 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, so it is the same as in the case of ferrite parts In addition, reducing the particle size of the raw material powder to make it fine is an important factor for improving the power generation efficiency.

  By the way, as an index for measuring that the powder is fine, a specific surface area is also used in addition to the particle diameter. It is known that the particle size and the specific surface area have the relationship of the following formula 1. Since the relationship of Equation 1 below is derived on the assumption that the particles are spherical, there is some error between the particle size obtained from Equation 1 and the actual particle size. However, it can be seen that the specific surface area increases as the particle size decreases.

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

  In recent years, reduction in impurity elements contained in nickel oxide powder has been demanded with the enhancement of functionality of ferrite parts and the expansion of applications of nickel oxide powder to electronic parts other than ferrite parts. Among these impurity elements, chlorine and sulfur react with silver used in the electrode to cause deterioration of the electrode and corrode the firing furnace, so it is desirable to reduce as much as possible. Further, it is desirable that sodium be reduced because sodium hinders sintering when the ferrite component is fired.

  Conventionally, as a method for producing nickel oxide powder, a method of using nickel sulfate as a raw material and baking it is known. For example, as described in Patent Document 1, first stage roasting with a roasting temperature of less than 950-1000 ° C. in an oxidizing atmosphere using nickel sulfate as a raw material and a roasting temperature of There is a method for producing nickel oxide powder that performs second-stage roasting at 1000 to 1200 ° C. According to Patent Document 1, a nickel oxide fine powder having an average particle diameter controlled by this method and a sulfur quality of 50 mass ppm or less is obtained.

  Patent Document 2 discloses a method for producing nickel oxide powder in which a dehydration step of raw material nickel sulfate by calcining at 450 to 600 ° C. and a decomposition step of nickel sulfate by roasting at 1000 to 1200 ° C. are clearly separated. Has been proposed. According to Patent Document 2, nickel oxide powder having a low sulfur quality and a small average particle size can be stably produced by this method.

  Furthermore, Patent Document 3 proposes a method of roasting nickel sulfate at a maximum temperature of 900 to 1250 ° C. while forcibly introducing air using a horizontal rotary manufacturing furnace. According to this manufacturing method, a nickel oxide powder with few impurities and a sulfur quality of 500 mass ppm or less is obtained.

  However, in any of the methods disclosed in Patent Documents 1 to 3, when the roasting temperature is increased to reduce the sulfur quality, the resulting nickel oxide powder has a coarse particle size, and the particles are made finer. Therefore, when the roasting temperature is lowered, the sulfur quality in the obtained nickel oxide powder is increased. Furthermore, in the above method, a gas containing SOx is generated during heating, and it is necessary to provide expensive equipment for removing the gas.

  On the other hand, as a method for producing nickel oxide powder, an aqueous solution containing a nickel salt such as nickel sulfate or nickel chloride is neutralized with an alkali such as an aqueous sodium hydroxide solution to crystallize nickel hydroxide and roasted. A method is also conceivable. For example, Patent Document 4 discloses that although it is an intermediate product when producing nickel powder, nickel oxide powder can be obtained by performing two-stage heat treatment of nickel hydroxide in an oxidizing atmosphere. Have been described.

  In such a method of roasting nickel hydroxide, since there is almost no generation of gas derived from an anionic component such as SOx, simple equipment may be used and production at low cost is possible. However, depending on the production conditions of nickel hydroxide, a few percent of anion-derived components may be mixed, and problems such as the occurrence of corrosion of equipment due to long-term production occur.

Japanese Patent Laid-Open No. 2001-032002 JP 2004-123488 A JP 2004-189530 A JP 2005-002395 A

  In view of the above-mentioned problems of the prior art, the present invention has a low impurity content, particularly a sulfur or chlorine content, and a fine particle size, and is used for manufacturing an electronic component or a solid oxide fuel cell. An object is to provide a fine nickel oxide powder suitable as a material and a method for producing the same.

  As a result of intensive studies to achieve the above object, the present inventor has obtained a method of obtaining nickel oxide fine powder from a raw nickel sulfate aqueous solution through an intermediate nickel hydroxide, that is, a nickel sulfate aqueous solution is neutralized with an alkali. The obtained nickel hydroxide powder is washed with a carbonate-containing aqueous solution, and the washed nickel hydroxide powder is heat-treated and pulverized to obtain fine nickel oxide fine particles with low sulfur and chlorine contents. The inventors have found that powder can be obtained and have completed the present invention.

  That is, the present invention relates to a nickel hydroxide powder used as a raw material for producing a nickel oxide fine powder and a method for producing the same, and a nickel oxide fine powder using the nickel hydroxide powder and a method for producing the same.

Specifically, in the method for producing nickel hydroxide powder for nickel oxide fine powder production raw material according to the present invention, a nickel sulfate aqueous solution having a nickel concentration of 50 to 180 g / l is pH 8.3 at a liquid temperature of 50 to 70 ° C. Step A to obtain nickel hydroxide powder by neutralizing with sodium hydroxide or potassium hydroxide as an alkali in the range of ˜9.0, and washing the obtained nickel hydroxide powder with carbonated water at a liquid temperature of 100 ° C. or less Step B is included .

  The nickel hydroxide powder obtained by the method for producing nickel hydroxide powder for nickel oxide fine powder production raw material according to the present invention has a sulfur content of 100 mass ppm or more and 1.0 mass% or less, and a chlorine content of 50 mass ppm. The sodium content is 100 mass ppm or less, and the mass reduction start temperature (hydroxyl desorption temperature) by TG-DTA measurement is less than 300 ° C.

  Further, the nickel oxide fine powder production method according to the present invention uses the nickel hydroxide powder obtained by the nickel hydroxide powder production method for the nickel oxide fine powder production raw material according to the present invention, and the nickel hydroxide powder is non-coated. A process C in which a nickel oxide powder is formed by heat treatment in a reducing atmosphere at a temperature higher than 850 ° C. and lower than 980 ° C., and a process D in which nickel oxide particles connected by sintering are crushed during the heat treatment. It is characterized by that. The crushing in the step D is preferably performed by causing the particles of the nickel oxide powder to collide with each other.

  The nickel oxide fine powder obtained by the nickel oxide fine powder production method according to the present invention has a sulfur content of 50 mass ppm or less, a chlorine content of 50 mass ppm or less, and a sodium content of 100 mass ppm or less, and D50 measured by the laser scattering method is 0.5 μm or less.

  According to the present invention, starting from an aqueous nickel sulfate solution, the sulfur quality is controlled to 50 mass ppm or less, the chlorine content is controlled to 50 mass ppm or less, the sodium quality is 100 mass ppm or less, and the impurity quality is low and fine. The nickel oxide fine powder can be easily produced at low cost without generating a large amount of chlorine or SOx gas. Further, the nickel oxide fine powder of the present invention is substantially free of zirconium and group 2 elements as impurities, has few impurities such as sulfur, chlorine and sodium, and is fine, so that it is an electronic component such as a ferrite component. It is suitable as a material or an electrode material of a solid oxide fuel cell.

  In the present invention, a method for producing nickel hydroxide powder for a raw material for producing nickel oxide fine powder includes a step A in which a nickel sulfate aqueous solution is neutralized with an alkali to obtain nickel hydroxide powder, and the obtained nickel hydroxide powder is carbonated. And a step B of washing with a root-containing aqueous solution. In addition, the nickel oxide fine powder production method according to the present invention includes a nickel oxide fine powder obtained by heat-treating the nickel hydroxide powder obtained in the above steps A to B in a non-reducing atmosphere at a temperature higher than 850 ° C. and lower than 980 ° C. A process C for forming powder and a process D for crushing nickel oxide particles connected by sintering during the heat treatment are provided.

[Nickel hydroxide powder and method for producing the same (steps A to B)]
In step A, nickel hydroxide is precipitated by neutralizing the aqueous nickel sulfate solution with an alkali. Known techniques can be applied to the concentration and neutralization conditions of the nickel sulfate aqueous solution. The nickel sulfate used for the raw material is not particularly limited, but in order to use the nickel oxide fine powder finally obtained by the present invention for an electronic component, the impurity in the nickel sulfate is preferably less than 100 ppm by mass. .

  The nickel concentration of the aqueous nickel sulfate solution is not particularly limited, but considering productivity, the nickel concentration in the aqueous solution is preferably in the range of 50 to 180 g / l, more preferably in the range of 50 to 120 g / l. . If the nickel concentration is less than 50 g / l, the productivity deteriorates. Conversely, if the nickel concentration exceeds 180 g / l, the concentration of anions such as sulfate groups in the aqueous solution becomes high, and the sulfur grade in the produced nickel hydroxide is low. Since it becomes high, the impurity quality in the nickel oxide fine powder finally obtained may not become low enough.

  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, and sodium hydroxide is particularly preferable in consideration of cost. In addition, although the said alkali may be added to nickel sulfate aqueous solution in any state of solid or liquid, it is preferable to use aqueous solution from the ease of handling. In order to obtain nickel hydroxide with uniform characteristics, it is effective to add a nickel salt aqueous solution and an alkaline aqueous solution in a sufficiently stirred reaction tank by a double jet method. At that time, the liquid previously placed in the reaction vessel is preferably a liquid adjusted to a predetermined pH by adding alkali to pure water.

  The pH in the neutralization reaction is preferably in the range of 8.3 to 9.0, and it is particularly preferable to keep the pH constant within this range. If the pH is lower than 8.3, anionic components such as chlorine and sulfuric acid remaining in nickel hydroxide increase, and a large amount of hydrochloric acid and SOx may be generated during heat treatment in step C during nickel oxide production. This is not preferable. On the other hand, if the pH is higher than 9.0, the resulting nickel hydroxide becomes too fine and filtration may be difficult. Moreover, sintering may progress too much at the process C, and it may become difficult to obtain fine nickel oxide. When the pH is 9.0 or less, a slight amount of nickel component may remain in the aqueous solution. In this case, the nickel hydroxide slurry is raised to about 10 to crystallize nickel after completion of the neutralization reaction. It is preferable.

  The liquid temperature during the neutralization reaction may be room temperature, but is preferably in the range of 50 to 70 ° C. in order to sufficiently grow the nickel hydroxide particles. By sufficiently growing the nickel hydroxide particles, it is possible to suppress the inclusion of sulfur as sulfate groups in the nickel hydroxide, and finally reduce the sulfur content of the nickel oxide fine powder. When the liquid temperature is less than 50 ° C., the nickel hydroxide particles do not grow sufficiently, and the amount of sulfur involved in the nickel hydroxide increases. On the other hand, when the liquid temperature exceeds 70 ° C., the evaporation of water becomes violent and the sulfur concentration in the aqueous solution increases, so that the sulfur content in the produced nickel hydroxide may increase.

  In the next step B, the nickel hydroxide powder precipitated by the neutralization reaction in step A and collected by filtration is washed with an aqueous carbonate group-containing solution (cleaning solution). By washing with this carbonate group-containing aqueous solution, the anion component and sulfur can be efficiently removed while suppressing the content of alkali components such as sodium. The carbonate radical-containing aqueous solution may be an aqueous solution containing carbonate ions or hydrogen carbonate ions, but an alkali carbonate aqueous solution such as sodium carbonate or potassium carbonate is preferred, and among them, a sodium carbonate aqueous solution is particularly preferred.

  By the method for producing nickel hydroxide powder of the present invention including the above-mentioned step B, the content of impurities, particularly the sulfur content, can be controlled within a suitable range as nickel hydroxide powder for nickel oxide fine powder production raw material. . The reason why the anion component and sulfur can be efficiently removed by washing with the carbonate-containing aqueous solution is not clear, but the anion component adsorbed on the surface of the crystallized nickel hydroxide particles, particularly sulfuric acid, is not clear. It is presumed that the anion component and sulfur can be efficiently washed away by removing the base and carbonate radicals by ion exchange, or by dissolving the nickel carbonate coated on the surface with a cleaning solution and removing the coating. Is done.

  When an aqueous sodium carbonate solution is used as the cleaning liquid, the sodium carbonate concentration of the cleaning liquid is preferably in the range of 1 to 20 g / l, more preferably in the range of 2 to 10 g / l. If the sodium carbonate concentration of the cleaning liquid is less than 1 g / l, the effect of removing the anion component by the cleaning may not be sufficiently obtained. Conversely, if it exceeds 20 g / l, the residual sodium content may be excessive.

  In the washing with the carbonate-containing aqueous solution, the washing effect is increased by heating, but if the temperature is raised too much, water evaporation and carbonate root volatilization occur, so water evaporation and carbonate root do not volatilize and washing. It is preferable to make the liquid temperature possible. For example, when an alkali carbonate aqueous solution is used as the cleaning liquid, the temperature of the cleaning liquid is preferably 100 ° C. or less, more preferably 20 to 80 ° C. If the temperature of the cleaning liquid exceeds 100 ° C., the evaporation of water and the volatilization of carbonate radicals are severe, and a sufficient cleaning effect cannot be obtained.

  Although it does not specifically limit as said washing | cleaning method, For example, it can wash | clean by making the nickel hydroxide powder obtained at the process A slurry with a washing | cleaning liquid, and stirring. Moreover, after slurrying, it can also wash | clean, crushing by wet crushing, for example, the method of making powder collide, According to this method, an impurity can be reduced further. Furthermore, it can also wash | clean by passing a washing | cleaning liquid through the nickel hydroxide powder in a filter using a filter press, a rotary filter, etc.

  The mixing ratio of the nickel hydroxide powder and the cleaning liquid is not particularly limited, and the nickel hydroxide powder can be satisfactorily dispersed, and the anions contained in the nickel hydroxide powder, particularly sulfate ions can be sufficiently removed. A mixing ratio may be used. For example, the mixing ratio of nickel hydroxide powder / cleaning liquid is preferably in the range of 50 to 300 g / l, more preferably in the range of 80 to 120 g / l. Also, the cleaning time may be a time during which residual anions are sufficiently reduced depending on the processing conditions. In addition, when the anion is not sufficiently reduced by one washing, it is preferable to repeat washing several times.

  In particular, when an alkali carbonate aqueous solution is used as the cleaning solution for the carbonate radical-containing aqueous solution, it is preferable to further wash the nickel hydroxide powder after washing with the alkali carbonate aqueous solution to sufficiently remove the remaining impurities. As water used for water washing, it is particularly preferable to use pure water.

  The nickel hydroxide powder for nickel oxide fine powder production raw material produced by the method of the above steps A to B has low impurity quality, particularly sulfur, chlorine, sodium content, and is dehydrated at a lower temperature than before. Since it can be nickel oxide, it is suitable as a raw material for producing nickel oxide fine powder for electronic component materials or fuel cell electrode materials. The specific impurity content is such that the sulfur content is 100 mass ppm or more and 1.0 mass% or less, the chlorine content is less than 50 mass ppm, and the sodium content is 100 mass ppm or less. Moreover, the mass decrease start temperature (hydroxyl desorption temperature) by TG-DTA measurement is less than 300 ° C.

  In the present invention, the mass decrease start temperature by TG-DTA measurement means that the temperature of nickel hydroxide is raised at 10 ° C./min in the air atmosphere using a TG-DTA measurement device, and the decrease start point of ΔTG (measurement) It was defined as the temperature when the mass decreased from the mass at the start by 5 mass%).

  The nickel hydroxide powder obtained in the steps A to B of the present invention is a raw material for producing nickel oxide fine powder, and by heat treatment, the hydroxyl group in the nickel hydroxide crystal is released to become nickel oxide. During this heat treatment, the particle size is reduced and sintering of the nickel oxide particles proceeds to some extent due to the influence of high temperature. However, as described above, the nickel hydroxide powder of the present invention has sufficiently reduced anion components such as sulfur and chlorine and has a low hydroxyl desorption temperature. Compared with the manufacturing method, it is possible to obtain a nickel oxide fine powder with a low impurity content by heat treatment at a lower temperature.

  That is, if the sulfur content exceeds 1.0 mass% or the chlorine content is 50 mass ppm or more, it is necessary to increase the heat treatment temperature in order to volatilize these anionic components. Then, a fine nickel oxide fine powder cannot be obtained. Moreover, since an anion component, especially a sulfuric acid group has the effect | action which accelerates | stimulates sintering, if it remains in large quantities, the nickel oxide obtained by heat processing will coarsen. However, since a small amount of sulfur has an effect of suppressing sintering, the sulfur content of the nickel hydroxide powder is 100 mass ppm or more and 1.0 mass% or less, preferably 200 mass ppm or more and 1.0 mass% or less. Preferably it is 500 mass ppm or more and 1.0 mass% or less. On the other hand, sodium remains without being volatilized even by heat treatment, but if its content exceeds 100 ppm by mass, the amount of sodium contained in the obtained nickel oxide fine powder becomes too large and promotes particle sintering. Therefore, it is not preferable.

[Nickel oxide fine powder and production method thereof (steps C to D)]
In Step C in the method for producing fine nickel oxide powder according to the present invention, the nickel hydroxide powder obtained in Steps A to B is used as a raw material, and the nickel hydroxide powder is more than 850 ° C. and 980 ° C. in a non-reducing atmosphere. The nickel oxide fine powder is formed by heat treatment at a temperature below.

  As described above, the nickel hydroxide powder used as the nickel oxide fine powder production raw material in the step C has an anion component sufficiently reduced, so that it exceeds 850 ° C. and less than 980 ° C., preferably 900 to 970 ° C. Fine nickel oxide particles can be obtained by heat treatment at a temperature. At a heat treatment temperature of 850 ° C. or lower, nickel oxide with good crystallinity cannot be obtained, and the handleability when used as an electronic component material or an electrode material is deteriorated. Further, the volatilization during the heat treatment is not sufficient, and the residual amount of impurities may increase. On the other hand, when the heat treatment temperature exceeds 980 ° C., the formed nickel oxide particles are sintered, so that fine nickel oxide particles cannot be obtained.

  The holding time at the heat treatment temperature is preferably 1 to 10 hours. When the holding time is less than 1 hour, the content of sulfur and chlorine in the nickel oxide fine powder may exceed 50 ppm by mass. Further, if the holding time exceeds 10 hours, not only is it not economical, but sintering between nickel oxide particles proceeds, and even if pulverized, D50 may exceed 0.5 μm, which is not preferable.

  The non-reducing atmosphere at the time of the heat treatment may be an atmosphere in which nickel hydroxide is decomposed to become nickel oxide. Among them, an oxidizing atmosphere is preferable, and an air atmosphere that is easy to handle is particularly preferable. The non-reducing atmosphere gas is preferably supplied at a flow rate that can sufficiently remove water vapor generated by the decomposition of nickel hydroxide.

  In the next step D, the nickel oxide powder obtained by the heat treatment in the step C is crushed to obtain the nickel oxide fine powder of the present invention. In step C, heat treatment at a low temperature is possible, and since the promotion of sintering of nickel oxide particles by an anionic component is suppressed, the resulting nickel oxide particles are fine. However, since nickel oxide particles linked by sintering are also partially generated during heat treatment, the nickel oxide particles linked by sintering are crushed, so that the D50 measured by the laser scattering method is 0.5 μm or less. The nickel oxide fine powder is obtained.

  The crushing process may be performed using a medium such as a ball mill or a bead mill, but in that case, impurities may be mixed from the medium. Therefore, in order to prevent impurities from entering from the media, it is preferable to crush the nickel oxide particles by colliding them without using the media. As a method of crushing particles by colliding them, for example, use of a jet mill such as a nanogrinding mill commercially available from Tokuju Kogakusho Co., Ltd. is preferable. Even in the case of pulverization using a jet mill, dry pulverization is preferably performed because wet pulverization causes agglomeration during drying and deteriorates the particle size distribution.

  The nickel oxide fine powder of the present invention obtained by the method comprising steps A to D described above has a sulfur content of 50 mass ppm or less, a chlorine content of 50 mass ppm or less, and a sodium content of 100 mass ppm or less. And D50 measured by the laser scattering method is 0.5 micrometer or less, It is characterized by the above-mentioned. In consideration of the handleability of the powder, D50 is preferably 0.05 to 0.5 μm, and more preferably 0.1 to 0.5 μm.

  In addition, since the above-described steps A to D do not include a step of adding a Group 2 element such as magnesium, it is virtually impossible that these elements are included as impurities in the nickel oxide fine powder. Furthermore, if crushing is performed without using a crushing medium, contamination with zirconia or the like can be prevented. Therefore, in the nickel oxide fine powder of the present invention, the content of zirconia and the Group 2 element can both be 30 ppm by mass or less.

  Thus, since the nickel oxide fine powder of the present invention has a very small impurity content and is composed of fine particles, it is used as a material for electronic parts such as ferrite parts or as an electrode material for solid oxide fuel cells. As such, it is extremely suitable. Moreover, it can be manufactured with high productivity without generating a large amount of chlorine or SOx gas by a simple manufacturing method. Moreover, since expensive equipment for removing harmful SOx is not necessary, the manufacturing cost can be kept low.

  The following examples illustrate the invention in more detail. In addition, the analysis of sulfur, chlorine, and sodium in Examples and Comparative Examples was performed by evaluating with a calibration curve method using an ICP emission spectroscopic analysis method and a fluorescent X-ray quantitative analysis device (manufactured by PANalytical, Magix).

  Further, the particle diameter of the nickel oxide fine powder was measured by a laser scattering method, and the particle diameter D50 at a volume integration of 50% was determined from the particle size distribution. The weight reduction start temperature (hydroxyl desorption temperature) was measured using TG-DTA2000 (manufactured by Bruker AXS), and the specific surface area was determined by the BET method using nitrogen gas adsorption.

[Example 1]
(Process A)
Sodium hydroxide was dissolved in pure water with a 10 liter beaker to prepare 1500 ml of an aqueous sodium hydroxide solution adjusted to pH 8.5. In this sodium hydroxide aqueous solution, a nickel sulfate aqueous solution prepared by dissolving nickel sulfate in pure water to adjust the nickel concentration to 120 g / l and a 12.5 mass% sodium hydroxide aqueous solution have a fluctuation range centering on pH 8.5. Was added and mixed continuously while adjusting the pH so that the absolute value was within 0.2, thereby forming a nickel hydroxide precipitate.

  The nickel sulfate aqueous solution was added at a rate of 24 ml / min. Moreover, liquid temperature was 60 degreeC and it stirred at 200 rpm with the stirring blade. After adding 3 liters of nickel sulfate aqueous solution, the mixture was aged while continuing stirring for about 3 hours. Thereafter, filtration and 30-minute pure water repulp were repeated four times to obtain a nickel hydroxide filter cake.

(Process B)
The obtained nickel hydroxide filter cake was mixed with a 2 g / l aqueous sodium carbonate solution as a cleaning solution to form a slurry having a concentration of 100 g / l. The slurry was stirred and washed for 5 hours, and then filtration and 30-minute pure water repulp were repeated four times to obtain a nickel hydroxide filter cake. The washed filter cake was dried in the air at 110 ° C. for 24 hours using a blow dryer, and Sample 1 nickel hydroxide powder was obtained.

  The obtained nickel hydroxide powder of Sample 1 had a sulfur content of 0.6 mass%, a chlorine content of less than 50 ppm by mass, and a sodium content of less than 100 ppm by mass. Moreover, the mass reduction start temperature by TG-DTA measurement was 250 degreeC.

In the step B, except that the concentration of coal Sanna thorium was 10 g / l in the same manner as the sample 1, to obtain a nickel hydroxide powder of Sample 2. The obtained nickel hydroxide powder of Sample 2 had a sulfur content of 0.7 mass%, a chlorine content of less than 50 mass ppm, and a sodium content of less than 100 mass ppm. Moreover, the mass reduction start temperature by TG-DTA measurement was 250 degreeC.

  In the above-described step B, the sample 3 was prepared in the same manner as in the sample 1 except that carbonated water obtained by blowing carbon dioxide gas into 10 liters of pure water at a rate of 1 liter / min for 30 minutes instead of the sodium carbonate aqueous solution was used as the cleaning solution. Nickel hydroxide powder was obtained. The obtained nickel hydroxide powder of Sample 3 had a sulfur content of 1.0 mass%, a chlorine content of less than 50 mass ppm, and a sodium content of less than 100 mass ppm. Moreover, the mass reduction start temperature by TG-DTA measurement was 250 degreeC.

[Comparative Example 1]
In step B of Example 1, a nickel hydroxide powder of Sample 4 was obtained in the same manner as Sample 1 except that pure water was used as the cleaning liquid. The obtained nickel hydroxide powder of Sample 4 had a sulfur content of 1.7 mass%, a chlorine content of less than 50 mass ppm, and a sodium content of less than 100 mass ppm. Moreover, the mass reduction start temperature by TG-DTA measurement was 300 degreeC.

  Further, in step B of Example 1, a nickel hydroxide powder of Sample 5 was obtained in the same manner as Sample 1 except that a 10 g / l sodium hydroxide aqueous solution was used as the cleaning liquid. The obtained nickel hydroxide powder of Sample 5 had a sulfur content of 0.6% by mass, a chlorine content of less than 50 ppm by mass, and a sodium content of 200 ppm by mass. Moreover, the mass reduction start temperature by TG-DTA measurement was 250 degreeC.

  About the samples 1-3 of the said Example 1 and the samples 4-5 of the comparative example 1, the used cleaning liquid, sulfur content of the obtained nickel hydroxide powder, chlorine content, sodium content, and TG-DTA measurement The mass decrease start temperature is summarized in Table 1 below.

  As can be seen from the above results, each of the nickel hydroxide powders of Samples 1 to 3 as an example of the present invention has a sulfur content of 100 mass ppm or more and 1.0 mass% or less, and a chlorine content of 50 mass ppm. And the sodium content is 100 ppm by mass or less, and the mass decrease start temperature (desorption temperature of hydroxyl group) in TG-DTA is as low as 250 ° C., which is suitable for a raw material for producing nickel oxide fine powder.

  On the other hand, Sample 4 as a comparative example is not washed with a carbonate-containing aqueous solution, so the sulfur content is as high as 1.7% by mass, and the mass decrease start temperature is as high as 300 ° C. Moreover, in sample 5, since sodium hydroxide aqueous solution was used as a washing | cleaning liquid, sodium content becomes very high with 200 mass%, and it turns out that it is not suitable for nickel oxide fine powder manufacture raw materials.

[Example 2]
(Process AB)
Step A and Step B in Example 1 were performed in the same manner as Sample 1, but the concentration of the sodium carbonate aqueous solution that was the cleaning liquid in Step B was changed to 5 g / l instead of 2 g / l in Sample 1, and Sample 6 Nickel hydroxide powder was obtained. The obtained nickel hydroxide powder of Sample 6 had a sulfur content of 0.39% by mass, a chlorine content of less than 50 ppm by mass, and a sodium content of less than 100 ppm by mass. Moreover, the mass reduction start temperature by TG-DTA measurement was 250 degreeC.

(Process C)
Nickel oxide fine powder was obtained by supplying 200 g of the obtained nickel hydroxide powder to a rolling batch firing furnace and heat-treating at 940 ° C. for 2 hours while continuously supplying air.

(Process D)
150 g fractioned from the obtained nickel oxide fine powder was pulverized using 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. Nickel fine powder was obtained.

  The obtained nickel oxide fine powder of Sample 6 had a sulfur content of 50 ppm by mass, a chlorine content of less than 50 ppm by mass, and a sodium content of less than 100 ppm by mass. D50 was 0.43 μm.

  In step C, a nickel oxide fine powder of sample 7 was obtained in the same manner as sample 6 except that the heat treatment time was 3 hours. The obtained nickel oxide fine powder of Sample 7 had a sulfur content of 32 mass ppm, a chlorine content of less than 50 mass ppm, and a sodium content of less than 100 mass ppm. Further, D50 was 0.44 μm.

  Further, in Step C, a nickel oxide fine powder of Sample 8 was obtained in the same manner as Sample 6 except that the heat treatment time was 5 hours. The obtained nickel oxide fine powder of Sample 8 had a sulfur content of 11 ppm by mass, a chlorine content of less than 50 ppm by mass, and a sodium content of less than 100 ppm by mass. D50 was 0.46 μm.

[Comparative Example 2]
A nickel oxide fine powder of Sample 9 was obtained in the same manner as in Example 2 except that the nickel hydroxide powder of Sample 4 of Comparative Example 1 (washed with pure water without washing with an aqueous sodium carbonate solution) was used. It was. The obtained nickel oxide fine powder of Sample 9 had a sulfur content of 64 mass ppm, a chlorine content of less than 50 mass ppm, and a sodium content of less than 100 mass ppm. Further, D50 was 0.44 μm.

  Further, a nickel oxide fine powder of Sample 10 was obtained in the same manner as Sample 9 of Comparative Example 2 except that the heat treatment time was 3 hours in Step C of Comparative Example 2. The obtained nickel oxide fine powder of Sample 10 had a sulfur content of 34 ppm by mass, a chlorine content of less than 50 ppm by mass, and a sodium content of less than 100 ppm by mass. Moreover, D50 was 0.55 micrometer.

  A nickel oxide fine powder of Sample 11 was obtained in the same manner as Sample 9 of Comparative Example 2 except that the heat treatment time was 5 hours in Step C of Comparative Example 2. The obtained nickel oxide fine powder of Sample 11 had a sulfur content of 13 mass ppm, a chlorine content of less than 50 mass ppm, and a sodium content of less than 100 mass ppm. Moreover, D50 was 0.57 micrometer.

  A nickel oxide fine powder of Sample 12 was obtained in the same manner as Sample 9 of Comparative Example 2 except that the heat treatment temperature was 960 ° C. and the heat treatment time was 3 hours in Step C of Comparative Example 2. The obtained nickel oxide fine powder of Sample 12 had a sulfur content of 10 ppm by mass, a chlorine content of less than 50 ppm by mass, and a sodium content of less than 100 ppm by mass. D50 was 0.61 μm.

[Comparative Example 3]
In step A of Example 1, a nickel hydroxide powder of Sample 13 was obtained in the same manner as Sample 1 of Example 1 except that a nickel chloride aqueous solution was used instead of the nickel sulfate aqueous solution. The obtained nickel hydroxide powder of Sample 13 had a sulfur content of less than 50 ppm by mass, a chlorine content of 210 ppm by mass, and a sodium content of less than 100 ppm by mass. Moreover, the mass reduction start temperature by TG-DTA measurement was 250 degreeC.

  A fine nickel oxide powder of Sample 13 was obtained in the same manner as Sample 6 of Example 2 except that the obtained nickel hydroxide powder of Sample 13 was used. The obtained nickel oxide fine powder of Sample 13 had a sulfur content of less than 50 ppm by mass, a chlorine content of less than 50 ppm by mass, and a sodium content of less than 100 ppm by mass. Moreover, D50 was 0.85 μm.

  About the sample 6-8 of above-mentioned Example 2, the samples 9-12 of the comparative example 2, and the sample 13 of the comparative example 3, the sulfur content of the obtained nickel hydroxide powder, chlorine content, sodium content, and TG- The mass decrease start temperature in the DTA measurement is shown in Table 2 below. Moreover, about each said sample, the calcination temperature and holding time in the process C are summarized in the following Table 3, and the sulfur content, chlorine content and sodium content, and D50 value of the obtained nickel oxide fine powder are summarized in the following Table 3. Showed.

  As can be seen from the above results, the nickel oxide fine powders of Samples 6 to 8, which are examples of the present invention, have a sulfur content of 50 mass ppm or less, a chlorine content of 50 mass ppm or less, and a sodium content of 100. It has a mass ppm or less and a D50 value of 0.5 μm or less and is highly pure and fine, and is suitable as an electronic component material such as a ferrite component or an electrode material of a solid oxide fuel cell.

On the other hand, the nickel oxide fine powders of Samples 9 to 11 which are comparative examples use nickel hydroxide powder having a high sulfur content obtained without washing with an aqueous sodium carbonate solution as a raw material, so that the sulfur content is 50 It exceeds mass ppm, or D50 exceeds 0.5 μm. Further, since the nickel oxide fine powder of Sample 12 has a high heat treatment temperature, D50 exceeds 0.5 μm, and none of the samples can be said to be suitable for electronic component materials. Furthermore, since the nickel oxide fine powder of Sample 13 uses nickel chloride as a raw material for producing nickel hydroxide, the sulfur content in the nickel hydroxide powder is reduced, and the particle sintering can be effectively suppressed. D50 exceeds 0.5 μm.

Claims (7)

Nickel hydroxide powder obtained by neutralizing an aqueous nickel sulfate solution having a nickel concentration of 50 to 180 g / l as an alkali with a pH of 8.3 to 9.0 at a liquid temperature of 50 to 70 ° C. with sodium hydroxide or potassium hydroxide. And a step B of washing the obtained nickel hydroxide powder with carbonated water at a liquid temperature of 100 ° C. or lower, and producing a nickel hydroxide powder for a nickel oxide fine powder production raw material Method. Characterized in that said alkali is sodium hydroxide, the production method of the nickel oxide nickel hydroxide powder for powder raw material according to claim 1. Hydroxylation with a sulfur content of 100 mass ppm or more and 1.0 mass% or less, a chlorine content of less than 50 mass ppm, a sodium content of 100 mass ppm or less, and a mass decrease starting temperature by TG-DTA measurement of less than 300 ° C. Nickel powder is obtained, The manufacturing method of the nickel hydroxide powder for the nickel oxide fine powder manufacturing raw material of Claim 1 or 2 characterized by the above-mentioned. The method for producing nickel hydroxide powder for nickel oxide fine powder production raw material according to claim 3 , wherein the nickel hydroxide powder has a sulfur content of 200 mass ppm or more and 1.0 mass% or less. . The nickel hydroxide powder obtained by the method for producing nickel hydroxide powder according to claim 3 or 4 is heat-treated in a non-reducing atmosphere at a temperature exceeding 850 ° C and less than 980 ° C to form a nickel oxide fine powder. A process for producing fine nickel oxide powder, comprising a process C and a process D for pulverizing nickel oxide particles connected by sintering during the heat treatment. The method for producing fine nickel oxide powder according to claim 5 , wherein the crushing in the step D is performed by causing the nickel oxide powder particles to collide with each other. A nickel oxide fine powder having a sulfur content of 50 mass ppm or less, a chlorine content of 50 mass ppm or less, a sodium content of 100 mass ppm or less, and a D50 measured by a laser scattering method of 0.5 μm or less is obtained. The manufacturing method of the nickel oxide fine powder of Claim 5 or 6 characterized by the above-mentioned.