JP2017014040A - Method for producing nickel oxide powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing nickel oxide powder, when nickel sulfate powder containing crystallized water is roasted to produce nickel oxide powder, capable of preventing the mixing of the exhaust gas of the first roasting furnace and the second roasting furnace, solving the destabilization of the corrosion and operation of equipment caused by the generation of sulfuric acid, and stabilizing product quality.SOLUTION: Provided is a method for producing nickel oxide powder where anhydrous nickel sulfate powder obtained in the first roasting furnace is fed into the second roasting furnace in a space between the exhaust chute 1 of the first roasting furnace and a charge chute 2 to the second roasting furnace using a communication equipment having an intermediate hopper 3, further, the lower edge opening part of the exhaust chute 1 opened at the inside of the intermediate hopper 3 and the lower edge opening part of the intermediate hopper 3 opened at the inside of the charge chute 2 are provided with gate valves 1a, 3a capable of gas sealing, and the inside of the intermediate hopper 3 is fed with pressurized air.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for producing nickel oxide powder by using nickel sulfate powder containing crystal water as a raw material and baking it.

  Nickel oxide powder is widely used industrially as a functional material such as an inductor, which is an electronic component, as a constituent material of ferrite, and as a thermal spray lining material for electrodes in soda electrolysis. Particularly in recent years, with the widespread use of mobile terminals such as small personal computers and smartphones and the improvement of their performance, there is a strong demand for electronic parts.

  Generally, nickel oxide powder as a ferrite raw material is mixed with other materials such as iron oxide and zinc oxide and sintered. However, in order to obtain a high-density and homogeneous sintered body, a small particle size is desired. It is rare. Further, when ferrite is used as an inductor, the silver forming the central coil is deteriorated by a sulfurization reaction, so that nickel oxide powder having a low sulfur content is required.

  On the other hand, in order to obtain a porous sintered body with a lower density, the nickel oxide powder for use as an electrode is required to have a larger particle size than that for use as an electronic component. As described above, nickel oxide powders are required to have a wide variety of quality and properties as functional materials. Therefore, in the production process of nickel oxide powders, it is very difficult to stably produce products that satisfy these requirements. Has become important.

  Such nickel oxide powder is generally produced by using a nickel compound such as nickel sulfate, nickel carbonate, nickel hydroxide or the like as a raw material and baking it in an oxidizing atmosphere using a kiln or other rolling furnace. For example, nickel oxide powder has been produced by using nickel sulfate powder containing crystal water as a raw material and baking it in a roasting furnace such as a rotary kiln.

  As a specific method for producing nickel oxide powder, for example, as shown in FIG. 1, nickel sulfate powder containing water of crystallization is used as a raw material, and this is quantitatively charged into a first roasting furnace, at 450 to 600 ° C. Calcined at temperature to obtain anhydrous nickel sulfate powder. The anhydrous nickel sulfate powder obtained in the first roasting furnace is supplied to the second roasting furnace using a communication facility, and nickel oxide powder is obtained by baking at a temperature of 950 to 1150 ° C.

  More specifically, first, nickel sulfate powder containing raw crystal water is calcined at a temperature of 450 to 600 ° C. in a first roasting furnace. By calcination in the first roasting furnace, for example, when the raw material nickel sulfate is hexahydrate, as shown in the following chemical formula 1, nickel sulfate hexahydrate is converted into anhydrous nickel sulfate by thermal decomposition, and crystals Water becomes steam and is carried away in the exhaust gas.

[Chemical 1]
NiSO ₄ · 6H ₂ O → NiSO ₄ + 6H ₂ O

The anhydrous nickel sulfate powder obtained in the first roasting furnace is sent to the second roasting furnace installed below by the communication facility, and further roasted at 950 to 1150 ° C. By roasting in the second roasting furnace, as shown in the following chemical formula 2 and chemical formula 3, anhydrous nickel sulfate is thermally decomposed to obtain nickel oxide powder. At that time, the sulfate radical (SO ₄ ) in the raw material is taken away into the exhaust gas as sulfuric acid gas (SO ₃ ) or sulfurous acid gas (SO ₂ ).

[Chemical formula 2]
NiSO ₄ → NiO + SO ₃
[Chemical formula 3]
NiSO ₄ → NiO + SO ₂ + 1 / 2O ₂

  In the first roasting furnace and the second roasting furnace, the generated gas is quickly discharged, and the gas in the gas phase portion at the particle interface of the powder thermally decomposed in the furnace is quickly replaced with air. In addition, as shown in FIG. 1, exhaust gas is discharged from the charging side by a suction device such as a fan while introducing free air from the discharge side of each roasting furnace. Moreover, since the components contained in the exhaust gas of the first roasting furnace and the exhaust gas of the second roasting furnace are different, the processing is performed by different exhaust gas treatment facilities.

That is, since the exhaust gas from the first roasting furnace contains fine dust generated from nickel sulfate containing crystal water or anhydrous nickel sulfate, these dusts are collected in a dust removal facility and then released to the atmosphere. On the other hand, the exhaust gas from the second roasting furnace is rendered harmless by absorbing the sulfuric acid gas (SO ₃ ) and sulfurous acid gas (SO ₂ ) in water or an alkaline aqueous solution by the cleaning tower type detoxification tower, To be released. Note that rotary kilns are generally used for the first and second roasting furnaces as the optimal equipment for quickly replacing the gas in the gas phase existing at the particle interface during pyrolysis in the furnace with air. Has been.

  As shown in FIG. 1, the anhydrous nickel sulfate powder obtained in the first roasting furnace has a lower second roasting furnace provided by a communication facility provided between the first roasting furnace and the second roasting furnace. To be supplied. As shown in FIG. 2, the communication facility is generally provided between the discharge chute 1 provided at the outlet of the first roasting furnace and the charging chute 2 provided at the inlet of the second roasting furnace. An intermediate hopper 3 is provided, and by the opening / closing operation of the gate valve 1a of the discharge chute 1 and the gate valve 3a of the intermediate hopper 3, the anhydrous nickel sulfate powder is delivered from the first roasting furnace to the second roasting furnace. It has become. A damper is generally used as the gate valve.

  On the other hand, regarding exhaust gas treatment of a reaction system, for example, Patent Document 1 discloses a moving bed type reaction tower filled with a granular adsorbent, a discharge conveyor for discharging the adsorbent from the bottom of the reaction tower, a reaction In an exhaust gas treatment apparatus provided with a supply conveyor for supplying adsorbent to the top of a tower, a first closed system formed by two automatic on-off valves is provided downstream of the outlet of the reaction tower, A second closed system formed by two automatic opening / closing valves is provided on the upstream side of the tower supply port, a gas supply port for making each closed system dry is provided, and the adsorbent in the moving bed is intermittently provided. An exhaust gas treatment device characterized in that it is configured to flow is disclosed.

  However, the above-mentioned patent document 1 is intermittently provided by providing a gas supply port for making the first and second closed systems dry in an apparatus that conventionally supplies and discharges the adsorbent continuously. It aims to simplify the device and reduce the height of the device. The supply of gas to each of the closed systems is a means for preventing the gas in the reaction tower from flowing out of the reaction tower.

  Patent Document 2 discloses a charging hopper having a charging port for charging waste, a melting furnace that melts waste charged in the charging hopper at a high temperature to make it harmless, and a gap between the charging hopper and the melting furnace. A multistage gate valve having a plurality of gate valves and a closed space partitioned by these gate valves and having a plurality of hopper chambers provided with gas supply nozzles for blowing inert gas into the closed space The system is filled with an inert gas through a gas supply nozzle in a closed space of a hopper chamber partitioned by a gate valve, and the pressure in the closed space is set higher by 98 to 980 Pa than the pressure in the furnace. In addition, a waste processing apparatus is disclosed that suppresses fluctuations in the pressure in the furnace when the waste is charged into the melting furnace.

  According to the above-mentioned Patent Document 2, it is possible to suppress fluctuations in the furnace pressure at the time of charging waste into the melting furnace, thereby maintaining a uniform combustion state in the furnace and improving combustion efficiency. In addition, it is described that even if the combustible gas in the generated gas is discharged outside the furnace, it does not come into contact with oxygen in the atmosphere, so there is no risk of fire or explosion.

  However, the methods and apparatuses disclosed in Patent Document 1 and Patent Document 2 described above are techniques for preventing the exhaust gas in the reaction tower and melting furnace from leaking to the outside, and nickel sulfate containing crystal water. Technology for preventing mixing of exhaust gas from each roasting furnace in a communication facility provided between the outlet of the first roasting furnace and the inlet of the second roasting furnace when producing nickel oxide powder using powder as a raw material Is different.

JP 11-137945 A Japanese Patent Laid-Open No. 2005-042954

As described above, in the method of producing nickel oxide powder using the nickel sulfate powder containing crystal water as a raw material and using the first roasting furnace and the second roasting furnace, the roasting in the second roasting furnace The negative pressure on the inlet side of the second roasting furnace is reduced to the first roasting temperature so that the generated exhaust gas containing sulfuric acid gas (SO ₃ ) and sulfurous acid gas (SO ₂ ) does not flow into the first roasting furnace through the communication facility. It is set higher than the exit side of the furnace. Therefore, even if the exhaust gas containing sulfuric acid gas (SO ₃ ) and sulfurous acid gas (SO ₂ ) generated in the second roasting furnace rises up to the charging chute to the second roasting furnace, it communicates in principle. It was thought that it would not enter the middle hopper of the facility.

However, since the temperature in the second roasting furnace is higher than the temperature in the first roasting furnace, it was generated in the second roasting furnace when the gate valve of the intermediate hopper was opened. An upward flow of exhaust gas containing sulfuric acid gas (SO ₃ ) or sulfurous acid gas (SO ₂ ) may be generated. Referring to FIG. 2, when the gate valve 3a of the intermediate hopper 3 is in an open state, an upward flow is generated from the second roasting furnace toward the first roasting furnace having a relatively low furnace temperature. Occur. At that time, sulfuric acid gas (SO ₃ ) or sulfurous acid gas (SO ₂ ) generated in the second roasting furnace passes through the open gate valve 3a and enters the intermediate hopper 3 and is generated in the first roasting furnace. Then, sulfuric acid is generated by mixing with the water vapor staying in the intermediate hopper 3.

  As a result, the generated sulfuric acid condenses, or the anhydrous nickel sulfate powder adheres to the condensed sulfuric acid to generate deposits, thereby causing malfunction of the gate valve and the second roasting furnace. Numerous factors impeding stable operation, such as poor supply of anhydrous nickel sulfate powder to the furnace or the occurrence of supply variations, may occur, and rarely corrosion may cause holes in the intermediate hopper, etc. . In such a case, operation must be stopped and maintenance must be performed, and production efficiency and cost will be seriously affected.

Further, when a part of the exhaust gas from the second roasting furnace reaches the first roasting furnace through the communication facility, sulfuric acid gas (SO ₃ ) and sulfurous acid gas (up to the exhaust gas treatment facility of the first roasting furnace ( SO ₂ ) will be introduced. In that case, since the measured value of the continuous SOx meter may exceed the threshold value, urgent measures against environmental troubles such as switching of the exhaust gas route or operation stop may be required.

  In addition, in the method of producing nickel oxide powder by using nickel sulfate powder containing crystal water as a raw material and roasting it, nickel sulfate is used as the nickel sulfate even if high-purity nickel sulfate powder is used as the raw material. However, depending on roasting conditions and the like, there is a problem that the sulfur content of the obtained nickel oxide powder tends to be high, and a solution has been desired.

  However, when the exhaust gas from the first roasting furnace and the exhaust gas from the second roasting furnace described above are mixed, sulfuric acid anhydride to the second roasting furnace is generated by the generation of deposits in the communication facility including the gate valve. Since the supply speed of the nickel powder fluctuates and the air flow state in the second roasting furnace deteriorates due to the deterioration of the sealing performance of the gate valve and the mixing of air from the hole, the sulfur of the nickel oxide powder obtained There has been a problem in terms of product quality that the content rate is increased and the variation of the sulfur content rate is increased.

  The present invention has been made in view of the above-mentioned problems of the prior art. In the method for producing nickel oxide powder by using nickel sulfate powder containing crystallization water as a raw material, the first roasting furnace is provided. Nickel oxide that prevents mixing of waste gas from the exhaust gas from the second roasting furnace, eliminates corrosion of equipment, generation of deposits, and unstable operation due to environmental problems, and stabilizes product quality A method for producing a powder is provided.

  As a result of intensive studies to achieve the above object, the present inventors have delivered anhydrous nickel sulfate powder disposed between the outlet of the first roasting furnace and the inlet of the second roasting furnace. In the communication facility, by supplying pressurized air to an intermediate hopper that can form a closed space by partitioning with a plurality of gate valves, the exhaust gas from the first roasting furnace and the exhaust gas from the second roasting furnace are mixed. The inventors have found that this can be prevented, and have completed the present invention.

  That is, in the method for producing nickel oxide powder of the present invention, nickel sulfate powder containing crystal water is calcined in a first roasting furnace to obtain anhydrous nickel sulfate powder, and the obtained anhydrous nickel sulfate powder is second roasted. In the method for producing nickel oxide powder by roasting in a furnace, the anhydrous nickel sulfate powder obtained in the first roasting furnace is used for the discharge chute of the first roasting furnace and the charging chute to the second roasting furnace. Gas is supplied to the lower roasting opening of the discharge chute opened in the intermediate hopper and the lower opening of the intermediate hopper opened in the charging chute while supplying to the second roasting furnace using a communication facility having an intermediate hopper in between. A gate valve capable of being sealed is provided, and pressurized air is supplied into the intermediate hopper.

  According to the present invention, when nickel oxide powder is produced by roasting nickel sulfate powder containing crystal water, a malfunction caused by mixing of exhaust gas from the first roasting furnace and exhaust gas from the second roasting furnace, In other words, the instability of the operation due to the corrosion of the equipment, the generation of deposits, environmental troubles, etc. can be eliminated, and the product quality can be stabilized.

It is the schematic which shows the process of using nickel sulfate containing crystal water as a raw material, and baking this, and manufacturing nickel oxide powder. It is a schematic sectional drawing which shows the communication equipment provided between the exit of a 1st roasting furnace, and the entrance of a 2nd roasting furnace. It is general | schematic sectional drawing which shows the supply process (a)-(d) of the anhydrous nickel sulfate powder from the exit of the 1st roasting furnace by the communication equipment to the entrance of the 2nd roasting furnace.

  In general, in the process of supplying anhydrous nickel sulfate powder from the outlet of the first roasting furnace to the inlet of the second roasting furnace using the communication facility, first, as shown in FIG. With both the valve 1a and the gate valve 3a of the intermediate hopper 3 closed, anhydrous nickel sulfate powder is charged into the discharge chute 1 from the outlet of the first roasting furnace (not shown). The addition of anhydrous nickel sulfate powder from the outlet of the first roasting furnace to the discharge chute 1 can be continued regardless of the open / close state of the gate valve 1a of the discharge chute 1.

  When a predetermined amount of anhydrous nickel sulfate powder accumulates in the discharge chute 1, as shown in FIG. 3 (b), the gate valve 1a of the discharge chute 1 opens, and the anhydrous nickel sulfate powder in the discharge chute 1 becomes the intermediate hopper 3. It is thrown into. Next, the gate valve 1a of the discharge chute 1 is closed, and as shown in FIG. 3C, the first roasting furnace with the gate valve 1a of the discharge chute 1 and the gate valve 3a of the intermediate hopper 3 closed together. The anhydrous nickel sulfate powder is continuously fed into the discharge chute 1 from the outlet.

  When a predetermined amount of anhydrous nickel sulfate powder accumulates in the intermediate hopper 3, as shown in FIG. 3D, the gate valve 3a of the intermediate hopper 3 is opened, and the anhydrous nickel sulfate powder in the intermediate hopper 3 is It is put into the charging chute 2 and supplied to a second roasting furnace (not shown). Thus, by repeating the operations of (a) to (d) in FIG. 3, the anhydrous nickel sulfate powder is first roasted without mixing the exhaust gas of the first roasting furnace and the exhaust gas of the second roasting furnace. It can be transferred from the furnace to the second roasting furnace.

However, as described above, in the conventional manufacturing method of nickel oxide powder, when the gate valve 3a of the intermediate hopper 3 is opened as shown in FIG. There was a problem that an upward flow of exhaust gas containing sulfuric acid gas (SO ₃ ) and sulfurous acid gas (SO ₂ ) tends to be generated toward one roasting furnace. Due to this upward flow, as already described, sulfuric acid is produced by reacting with the water vapor in the exhaust gas generated in the first roasting furnace in the intermediate hopper 3 of the communication equipment. Generation of kimono, etc. occurred, causing unstable operation.

  Therefore, in the present invention, the anhydrous nickel sulfate powder obtained in the first roasting furnace is transferred to the second roasting furnace using a communication facility in which a discharge chute, an intermediate hopper, and a charging chute are arranged in order in the vertical direction. In addition to the supply, a gate valve capable of gas sealing is provided at the lower end opening of the discharge chute opened in the intermediate hopper and the lower end opening of the intermediate hopper opened in the charging chute, and pressurized air is supplied into the intermediate hopper. Supply. By supplying the pressurized air into the intermediate hopper, the generation of the upward flow from the second roasting furnace to the first roasting furnace can be suppressed, and the generation of sulfuric acid can be eliminated.

  In addition, when nickel sulfate powder containing crystallization water is used as a raw material for producing nickel oxide powder, nickel sulfate powder has a regular crystal structure, so that nickel oxide powder having a small particle size and a narrow particle size distribution can be obtained. There is. Such a nickel oxide powder having a small particle size and a narrow particle size distribution is extremely good as a ferrite raw material for electronic parts. However, regarding the sulfur content of the resulting nickel oxide powder, even if high-purity nickel sulfate powder is used as a raw material, it contains sulfur in an equimolar amount with nickel. There was a problem that the content rate tends to be high.

  In order to lower the sulfur content of the resulting nickel oxide powder, basically, the roasting temperature in the second roasting furnace should be increased to increase the thermal decomposition reaction rate of anhydrous nickel sulfate. It is known. However, when the roasting temperature in the second roasting furnace is increased, the particle diameter of the resulting nickel oxide powder increases, that is, the secondary particles obtained by sintering the primary particles are more easily enlarged. is there.

On the other hand, in the thermal decomposition reaction of anhydrous nickel sulfate, the reaction proceeds at a high gas diffusivity rate. Therefore, as a measure for reducing the sulfur content of the resulting nickel oxide powder, SO ₃ and SO ₃ in the gas phase part of the particle interface are used. It is effective to reduce the concentration of ₂ . For this purpose, it is important to uniformly apply air to the particle surface to replace the SO ₃ gas or SO ₂ gas in the gas phase at the particle interface with air, and to keep the supply rate of anhydrous nickel sulfate as constant as possible. become.

  In summary, in order to stably produce nickel oxide powder having a small particle size and low sulfur content by the method for producing nickel oxide powder of the present invention, pressurized air is supplied into the intermediate hopper as described above. In addition, air is uniformly distributed on the surface of the powder particles by keeping the feed rate of the anhydrous nickel sulfate powder as a raw material as constant as possible without increasing the roasting temperature in the second roasting furnace as much as possible. It is important to guess.

However, excessive supply of pressurized air into the intermediate hopper is effective for separating the exhaust gas from the first roasting furnace and the exhaust gas from the second roasting furnace as described above, but originally the second roasting furnace. Instead of free air that should be introduced from the discharge side, air (pressurized air) is introduced from the charging side. As a result, the amount of free air on the discharge side is reduced by the amount of pressurized air supplied, and the replacement efficiency of sulfuric acid gas (SO ₃ ) and sulfurous acid gas (SO ₂ ) in the second roasting furnace is reduced. The sulfur content of the nickel oxide powder is likely to be high. On the other hand, if the supply amount of the pressurized air is too small, the original effect of the present invention of preventing mixing of the exhaust gas of the first roasting furnace and the exhaust gas of the second roasting furnace cannot be obtained.

  Considering these points, the gauge pressure in the intermediate hopper supplying the pressurized air is determined in the state where the closed valves are formed by closing the lower end opening of the discharge chute and the lower end opening of the intermediate hopper. 490 to 980 Pa (50 to 100 mm water column). At this time, it is preferable to supply the flow rate at which the inside of the intermediate hopper becomes the gauge pressure, instead of the pressure control, and set the flow rate control. An important factor that determines the sulfur content of the nickel oxide powder is the amount of free air introduced from the discharge side of the second roasting furnace, and the decrease in gauge pressure in the intermediate hopper is a secondary factor of the present invention. This is because the deterioration of the sealing performance of the gate valve can be detected as an effect.

[Conventional example]
The nickel sulfate powder containing crystal water, which is a raw material, is calcined in a first roasting furnace to obtain anhydrous nickel sulfate powder, and the obtained anhydrous nickel sulfate powder is roasted in a second roasting furnace, thereby obtaining nickel oxide. The operation for producing the powder was continued for about 9 months. As the first roasting furnace, an externally heated rotary kiln made of stainless steel having an outer diameter of 800 mm and a length of 10.5 m was used. As the second roasting furnace, Ni-Cr-W having an outer diameter of 827 mm and a length of 9 m was used. An alloy externally heated rotary kiln was used.

  Between the outlet of the first roasting furnace and the inlet of the second roasting furnace, as shown in FIG. 2, a discharge chute 1, an intermediate hopper 3, and a charging chute 2 are arranged in order in the vertical direction. Communication equipment was installed. The operating conditions were as follows: the amount of nickel sulfate powder charged into the first roasting furnace was 90 to 120 kg / h, the calcination temperature of the first roasting furnace was 450 to 600 ° C., and the rotation speed was 0.33 rpm. The roasting temperature of 2 roasting furnaces was 950-1150 ° C. and the rotation speed was 1 rpm.

  The nickel sulfate powder used as a raw material has Ni of 22.3% by weight, Co of less than 10 ppm by weight, Cu of less than 1 ppm by weight, Fe of less than 1 ppm by weight, Zn of less than 1 ppm by weight, and Mg of 100 ppm by weight. Less than 50 ppm by weight, Na less than 20 ppm by weight, and Ca less than 30 ppm by weight.

  The roasted product discharged from the second roasting furnace was cooled to room temperature and then pulverized with an atomizer to obtain nickel oxide powder. The sulfur content of the obtained nickel oxide powder was measured for each lot by a high frequency combustion-infrared absorption method. The size of one lot is 1 to 2 t, which corresponds to the output for 1 to 4 days.

  As a result, the sulfur content of the obtained nickel oxide powder was 592 ppm by weight on average, and the standard deviation was 211 ppm by weight. In addition, since the gate valve on the inlet side and the outlet side of the intermediate hopper corroded during the continuous operation for about 9 months, the replacement work was performed twice. Moreover, about the SOx density | concentration in the exhaust gas of a 1st roasting furnace, the trouble exceeding a control value generate | occur | produced 3 times.

[Example 1]
The same conditions as in the above conventional example except that the same first roasting furnace and second roasting furnace as in the above conventional example and communication equipment are used and pressurized air is supplied into the intermediate hopper 2 at a flow rate of about 1 m ³ / min. Thus, the operation of producing the nickel oxide powder by roasting the nickel sulfate powder containing the raw crystal water was continued for about 9 months. The gauge pressure in the intermediate hopper is 490 to 980 Pa (50 to 100 mm water column) in a state in which the closed valve is formed by closing the lower end opening of the discharge chute and the lower end opening of the intermediate hopper. The range was adjusted.

  As a result, the sulfur content of the obtained nickel oxide powder was 314 ppm by weight on average, and the standard deviation was 65 ppm by weight. Moreover, no corrosion of the intermediate hopper including the gate valve was observed, and it was not necessary to carry out replacement work. Moreover, the trouble which exceeded a control value did not generate | occur | produce also about the SOx density | concentration in the waste gas of a 1st roasting furnace.

  From the above results, by the practice of the present invention, malfunctions caused by mixing of the exhaust gas of the first roasting furnace and the exhaust gas of the second roasting furnace, that is, corrosion of equipment, generation of deposits, and unstable operation due to environmental troubles It can be seen that product quality can be eliminated and product quality can be stabilized.

1 Discharge chute 1a Gate valve 2 Charging chute 3 Intermediate hopper 3a Gate valve

Claims (2)

Method of producing nickel oxide powder by calcining nickel sulfate powder containing crystal water in first roasting furnace to make anhydrous nickel sulfate powder and roasting obtained anhydrous nickel sulfate powder in second roasting furnace In
The anhydrous nickel sulfate powder obtained in the first roasting furnace is second roasted using a communication facility having an intermediate hopper between the discharge chute of the first roasting furnace and the charging chute to the second roasting furnace. A gate valve capable of gas sealing is provided at the lower end opening of the discharge chute opened in the intermediate hopper and the lower end opening of the intermediate hopper opened in the charging chute, and pressurized in the intermediate hopper. The manufacturing method of the nickel oxide powder characterized by supplying air. The gauge pressure of the intermediate hopper is controlled within a range of 490 to 980 Pa in a state where a closed valve is formed by closing a lower end opening of the discharge chute and a lower end opening of the intermediate hopper. The method for producing a nickel oxide powder according to claim 1.

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