JP2000042444A - Grinding system for oxidizing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable grinding and classification smoothly and continuously to stabilize quality by arranging a classifier classifying a ground oxidizing material to a grinder and supplying an inert gas to the grinder to grind and classify the oxidizing material in the inert atmosphere. SOLUTION: A vertical mill 1 is constituted so that a classifier 3 is integrally arranged above a grinder 2 and, in the grinder 2, a roller is arranged on a rotatable table so as to be pressed to the table by hydraulic pressure and a raw material A is supplied to the gap between the table and the roller to be ground. Inert gas B such as argon or nitrogen is supplied from the lower part of the grinder 2 to grind the raw material A by the grinder 2 and the obtained powder is supplied to the classifier 3 to be classified by centrifugal force. Inert gas C is supplied to the classifier 3 by a compressor 4 to accelerate the revolving streams in the classifier 3 and the clogging with a powder is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for crushing and classifying an oxidizing material such as a hydrogen storage alloy.

[0002]

2. Description of the Related Art Generally, a hydrogen storage alloy is used as a negative electrode material of a nickel-metal hydride battery which is a kind of a secondary battery (a battery capable of charging and discharging). The negative electrode material is obtained by eroding a hydrogen storage alloy in a punching metal. In order to improve the performance of a battery, it is necessary to make the hydrogen storage alloy finer and increase the specific surface area of the powder. By the way, the hydrogen storage alloy is highly ignitable, and has conventionally been pulverized by a wet ball mill or the like using a medium (water, organic solvent) while being isolated from the atmosphere. Also, in order to improve the performance of the battery, such as an increase in the charge capacity, under conditions that are isolated from the atmosphere,
It is necessary to grind the hydrogen storage alloy so as not to be oxidized.

[0003]

However, mass production is difficult in the above-mentioned conventional wet pulverization, and there is a problem that the running cost is considerably increased as compared with the dry pulverization. In addition, it is necessary to classify the crushed powder to improve the performance and to differentiate the product (to align the particles), but conventionally, the classification operation cannot be performed continuously to the crushing operation. However, once the ground powder is packed (sealed) and transported to a classifier, the pack is opened and the classification operation is performed. Depending on the method of controlling the concentration of the inert atmosphere, there is some leakage, There is a problem that the function of the hydrogen storage alloy is impaired due to oxidation. Therefore, there is a problem that a dedicated classification facility is required.

[0004] The present invention has been made in view of the above circumstances, and an object of the present invention is to smoothly and continuously provide an oxidizing material such as a hydrogen storage alloy under an inert atmosphere isolated from the atmosphere. An object of the present invention is to provide an oxidizing material pulverizing system which can be pulverized and classified, and which can reliably and inexpensively produce fine powder of an oxidizing material having stable quality.

[0005]

According to a first aspect of the present invention, a crusher for crushing an oxidizing material is provided with a classifier for classifying the oxidizing material crushed by the crushing machine. The oxidizing material is pulverized and classified in an inert atmosphere by supplying an inert gas. According to the first aspect, the oxidizing material is supplied to a pulverizer in an inert atmosphere to be pulverized, and the pulverized powder is sent from the pulverizer to a classifier by an inert gas to be classified. Claim 2 of the present invention supplies an inert gas to a classifier. According to the second aspect, by sending the inert gas to the classifier, the classification operation in the classifier is promoted, and the occurrence of blockage at the time of classification is prevented. According to a third aspect of the present invention, a classifier is connected to a solid-gas separation means for collecting flour, and the pulverizer, the classifier and the solid-gas separation means are arranged in an inert atmosphere maintaining section. According to the third aspect, the powder pulverized by the pulverizer and classified by the classifier is separated into powder and gas by solid-gas separation means under an inert atmosphere in the inert atmosphere maintaining section. According to a fourth aspect of the present invention, an exhaust means for exhausting the exhaust gas of the solid-gas separation means to the outside of the inert atmosphere maintaining part is provided. An adjusting means is provided. According to the fourth aspect, when the solid-gas separation means discharges the gas (exhaust) separated from the flour to the outside of the inert atmosphere maintaining section by the exhaust means, the inside of the inert atmosphere maintaining section is externally controlled by the pressure adjusting means. As a result, it is possible to prevent the exhaust gas from flowing into the inert atmosphere maintaining section by preventing the pressure from becoming negative. According to a fifth aspect of the present invention, the exhaust means is provided with an atmospheric backflow preventing means for preventing the air from flowing into the inert atmosphere maintaining section. According to the present invention, when the pressure in the inert atmosphere maintaining section becomes negative, the air is prevented from flowing into the inert atmosphere maintaining section by the air backflow prevention means. Claim 6 of the present invention
Is for returning exhaust gas discharged from the inert atmosphere maintaining section by the exhaust means to the inert atmosphere maintaining section via the oxygen removing means. According to the present invention, the oxygen is removed from the exhaust gas discharged to the outside of the inert atmosphere maintaining section by the oxygen removing means and returned to the inert atmosphere maintaining section, so that the inert gas can be effectively used. Aim. A seventh aspect of the present invention is to adjust the temperature in the inert atmosphere maintaining section. According to the seventh aspect, by controlling the temperature in the inert atmosphere maintaining section to fall within a predetermined range, the inside of the inert atmosphere maintaining section is safely and kept at a predetermined pressure state. An eighth aspect of the present invention is to measure the oxygen concentration in the inert atmosphere maintaining section and adjust the inert gas to be supplied into the inert atmosphere maintaining section based on the result. According to the present invention, the oxygen concentration in the inert atmosphere maintaining section is increased by measuring the oxygen concentration in the inert atmosphere maintaining section and adjusting the amount of the inert gas supplied to the inert atmosphere maintaining section. Control not to.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an example of a flowchart of pulverizing a hydrogen storage alloy showing one embodiment of the present invention. In this figure, reference numeral 1 denotes a vertical mill. This vertical mill 1 has a classifier 3 integrally installed above a roller mill (pulverizer) 2. In the roller mill 2, a roller which is pressed against the table side by hydraulic pressure is arranged on a rotatable table, and a raw material (oxidizing material) A is supplied between the table and the roller to be pulverized. ing.

The roller mill 2 is supplied with an inert gas B such as argon or nitrogen from the lower portion thereof, and the powder crushed by the roller mill 2 is supplied to the classifier 3 by the inert gas B. It is sent and classified by centrifugal force. Further, an inert gas C for promoting the swirling flow in the classifier 3 and preventing clogging of the powder is supplied to the classifier 3 by the compressor 4. In the case where the classifier 3 of the vertical mill 1 does not require a gas for preventing clogging of powder, the inert gas C need not be supplied. Further, the roller mill 2 is provided with a temperature measuring means 5 for measuring the temperature inside the roller mill 2.

The classifier 3 has a solid-gas separation means as
The cyclone separator 6 and the bag filter 7 are connected to each other, and milling D and E are collected from lower ends of the cyclone separator 6 and the bag filter 7.
The exhaust air from the bag filter 7 is exhausted through an exhaust fan (exhaust means) 8. The vertical mill 1, the cyclone separator 6, the bag filter 7, the compressor 4 and the exhaust 8 are installed in an inert atmosphere maintaining section 9 for holding an inert atmosphere (argon, nitrogen, etc.). The compressor 4 and the exhaust 8 are
If the structure does not allow the air to enter inside, it may be installed outside the inert atmosphere maintaining unit 9.

On the discharge side of the blower 8, a pressure adjusting valve (pressure) for detecting the pressure in the inert atmosphere maintaining section 9 and adjusting the inside of the inert atmosphere maintaining section 9 so as not to become a negative pressure. The pressure regulating valve 1 is connected to the pressure regulating valve 1.
0 is connected to an atmospheric backflow prevention tank 11. The atmospheric backflow prevention tank 11 is connected to the inert atmosphere maintaining section 9 via an oxygen removing device (oxygen removing means) 12. Further, the atmospheric backflow prevention tank 11 is connected to the atmosphere side via a backflow prevention valve 13.

The inert atmosphere maintaining section 9 is provided with an oxygen concentration meter 14 for sampling the internal atmosphere gas and measuring the oxygen concentration.
Means for supplying inert gas 1 based on the oxygen concentration measured by
5, the flow rate of the inert gas F supplied to the inert atmosphere maintaining unit 9 is adjusted. Further, the inert atmosphere maintaining section 9 is provided with an air conditioner 16 for controlling the internal temperature and maintaining the temperature of the inert gas.

In the oxidizing material pulverizing system configured as described above, when the hydrogen storage alloy is pulverized and classified and collected as powder, first, the inert atmosphere maintaining unit 9 is used.
In a state where the inside is in an inert atmosphere, the raw material A is supplied into the roller mill 2, the inert gas B is supplied from below the roller mill 2, and the inert gas C is supplied into the classifier 3 as necessary. I do.

In this state, when the raw material A is pulverized by the roller mill 2, the pulverized powder is taken up by the classifier 3 by the inert gas B, and is centrifuged in the classifier 3 by centrifugal force. Classified. In this case, the particle size of the powder to be classified can be changed by adjusting the operating conditions of the classifier 3. Then, the powder having a particle size larger than the predetermined value is returned to the roller mill 2 and pulverized again, and the powder having a particle size equal to or smaller than the predetermined value is sent to the cyclone separator 6 and the bag filter 7, where the powder D, While extracted as E, the exhaust air of the bag filter 7 is stored in the atmospheric backflow prevention tank 11 by the exhaust fan 8 via the pressure adjusting valve 10.

In this case, the pressure regulating valve 10 adjusts the valve so that the pressure in the inert atmosphere maintaining section 9 does not become at least a negative pressure.
The atmosphere does not flow into the inside and the inert atmosphere maintaining unit 9
Inside is kept in a healthy state. If the pressure becomes negative, the gas in the air backflow prevention tank 11 only returns to the inert atmosphere maintaining unit 9, and the air flows into the inert atmosphere maintaining unit 9. Never. further,
The gas in the atmosphere backflow prevention tank 11 is returned to the inert atmosphere maintaining unit 9 in a state where oxygen is removed therefrom via the oxygen removing device 12, and the inert gas is reused. Furthermore, when the pressure in the atmospheric backflow prevention tank 11 exceeds a predetermined value, the gas in the atmospheric backflow prevention tank 11 is exhausted to the outside via the backflow prevention valve 13 as exhaust gas G.

The oxygen concentration in the inert atmosphere maintaining unit 9 is measured by the oxygen concentration meter 14, and the inert gas supplied from the inert gas supply unit 15 into the inert atmosphere maintaining unit 9 is measured according to the measurement result. By adjusting the flow rate of the active gas, the inert atmosphere in the inert atmosphere maintaining unit 9 is reliably maintained in a normal state. In addition, air conditioner 1
6, the temperature in the inert atmosphere maintaining unit 9 is controlled so as to be within a predetermined range, so that the temperature in the roller mill 2 rises beyond the predetermined range and does not hinder pulverization. In addition, the temperature in the inert atmosphere maintaining unit 9 does not drop below a predetermined range, and the pressure in the inert atmosphere maintaining unit 9 does not become negative.

As described above, in this embodiment, since the crusher 2 and the classifier 3 are integrated, it is easier to maintain a constant atmosphere than other types of dry crushers. Thereby, the amount of inert gas for maintaining the atmosphere constant can be reduced. Also, grinding, classification,
Since each process of milling recovery is performed continuously and the atmosphere of each process is kept the same and constant, the milling is hardly oxidized and the quality of the milling is hardly deteriorated. Can be maintained at a constant high level.

Furthermore, the vertical mill 1 of the present embodiment can easily obtain a powder having a sharp particle size, and can obtain a powder having an arbitrary particle size (several tens μm to submicron) at a low cost. Therefore, for example, by using a hydrogen storage alloy powder having a sharp particle size, even if the powder has the same particle size, cracks occur inside the particles and the surface area is increased, thereby improving the performance of the nickel-metal hydride battery. Can be done. This embodiment is applicable to all hydrogen storage alloys such as a lanthanum-nickel alloy (rare earth alloy), a titanium-iron alloy, and a magnesium-nickel alloy, and includes an oxidizing powder such as a powder having an ignitability. Application to grinding of materials is also possible. In addition, materials usually increase surface area as they are miniaturized, and some materials ignite and explode in the air at certain concentrations. Moreover, even if it does not refine, Na,
There are also compounds whose surface is easily oxidized such as Mg compounds.
It is needless to say that the present invention can be applied to such a material which is easily oxidized and a material having a risk of dust explosion. In this embodiment, the classifier 3 is integrally installed above the pulverizer 2. However, the fine powder is conveyed from the pulverizer 2 to the classifier 3 in an inert gas. If so, their positional relationship does not matter. Further, in the present embodiment, a group of particles that have been pulverized to a certain particle size or less are taken out as a product, and a group of particles larger than the target is classified, and circulated again to the pulverizer, whereby the powder is milled. The case where the present invention is applied to a closed-circuit pulverizing system that improves the quality of the product and reduces the yield has been described.

[0017]

According to a first aspect of the present invention, a classifier for classifying oxidized material pulverized by the pulverizer is disposed in a pulverizer for pulverizing an oxidizable material, and inert gas is supplied to the pulverizer. Since the oxidizing material is supplied and pulverized and classified under an inert atmosphere, the oxidizing material is supplied to a pulverizer under an inert atmosphere and pulverized. By sending the active gas to the classifier from the pulverizer and classifying, the oxidizing material such as a hydrogen storage alloy can be smoothly and continuously pulverized and classified under an inert atmosphere isolated from the atmosphere, Fine powder of an oxidizing material having stable quality can be produced inexpensively and reliably. Since claim 2 of the present invention supplies an inert gas to the classifier, the inert gas supplied to the classifier can accelerate the classifying operation in the classifier, and can prevent blockage during classification. Generation can be prevented beforehand. According to a third aspect of the present invention, since the classifier is connected to a solid-gas separation means for collecting flour, and the crusher, the classifier and the solid-gas separation means are arranged in the inert atmosphere maintaining section, the present invention is not limited to this. Under the inert atmosphere in the active atmosphere maintaining section, each of the processes of pulverization, classification and collection of the flour is performed by separating the powder pulverized by the pulverizer and classified by the classifier into flour and gas by solid-gas separation means. Can be performed under the same and constant inert atmosphere, and a high-quality mill can be produced in a stable state. According to a fourth aspect of the present invention, an exhaust means for exhausting the exhaust gas of the solid-gas separation means to the outside of the inert atmosphere maintaining part is provided. Since the adjusting means is provided, when the solid-gas separating means discharges the gas (exhaust) separated from the milling to the outside of the inert atmosphere maintaining section by the exhausting means, the inside of the inert atmosphere maintaining section is controlled by the pressure adjusting means. By preventing the negative pressure from being lower than that of the outside, it is possible to prevent the exhaust gas from flowing into the inert atmosphere maintaining portion. Claim 5 of the present invention
Since the exhaust means is provided with an air backflow prevention means for preventing the air from flowing into the inert atmosphere maintaining section, when the pressure in the inert atmosphere maintaining section becomes negative, In addition, it is possible to prevent the air from flowing into the inert atmosphere maintaining section. Claim 6 of the present invention
Since the exhaust gas discharged from the inert atmosphere maintaining unit by the exhaust means is returned to the inert atmosphere maintaining unit via the oxygen removing means, the exhaust gas discharged to the outside of the inert atmosphere maintaining unit is By removing the oxygen by the oxygen removing means and returning the oxygen to the inert atmosphere maintaining section, the inert gas can be effectively used. Claim 7 of the present invention
Since the temperature in the inert atmosphere maintaining section is adjusted, the temperature in the inert atmosphere maintaining section is controlled so as to fall within a predetermined range, so that the inside of the inert atmosphere maintaining section is maintained safely and at a predetermined pressure state. can do. According to an eighth aspect of the present invention, the oxygen concentration in the inert atmosphere maintaining section is measured, and the inert gas supplied to the inert atmosphere maintaining section is adjusted based on the result. By adjusting the amount of the inert gas supplied into the inert atmosphere maintaining section according to the oxygen concentration in the section, it is possible to control the oxygen concentration in the inert atmosphere maintaining section so as not to increase.

[Brief description of the drawings]

FIG. 1 is a flow chart of pulverizing a hydrogen storage alloy showing one embodiment of the present invention.

[Explanation of symbols]

 2 roller mill (pulverizer) 3 classifier 5 temperature measuring means 6 cyclone separator 7 bag filter 8 exhaust fan (exhaust means) 9 inert atmosphere maintaining unit 10 pressure regulating valve (pressure regulating means) 11 atmospheric backflow prevention tank (atmospheric backflow) Prevention means) 12 Oxygen removal device (Oxygen removal means) 13 Backflow prevention valve (Atmospheric backflow prevention means) 14 Oxygen meter 15 Inert gas supply means 16 Air conditioner A Raw material (oxidizing material) B, C, F Inactive Gas D, E milling

Claims (8)

[Claims] 1. A crusher for crushing an oxidizing material is provided with a classifier for classifying the oxidizing material crushed by the crushing machine. A crushing system for oxidizing materials, wherein the crushing and classification of oxidizing materials are performed by using the method. 2. The system according to claim 1, wherein an inert gas is supplied to the classifier. 3. The method according to claim 1, wherein a solid-gas separation means for collecting the flour is connected to the classifier, and the pulverizer, the classifier and the solid-gas separation means are arranged in an inert atmosphere maintaining section.
Or a crushing system for oxidizing materials according to 2 above. 4. An exhaust means for discharging the exhaust gas from the solid-gas separation means to the outside of the inert atmosphere maintaining part, wherein the exhaust means includes a pressure adjusting means for adjusting the inside of the inert atmosphere maintaining part so as not to have a negative pressure. 4. The oxidizing material grinding system according to claim 3, wherein the oxidizing material grinding system is provided. 5. The oxidizing material pulverizing system according to claim 4, wherein the exhaust means is provided with an atmospheric backflow preventing means for preventing an air from flowing into the inert atmosphere maintaining section. 6. The system according to claim 4, wherein the exhaust gas discharged from the inert atmosphere maintaining unit by the exhaust means is returned to the inert atmosphere maintaining unit via the oxygen removing means.
A oxidizing material grinding system as described. 7. The oxidizing material crushing system according to claim 3, wherein the temperature in the inert atmosphere maintaining section is adjusted. 8. The method according to claim 3, wherein an oxygen concentration in the inert atmosphere maintaining section is measured, and an inert gas supplied into the inert atmosphere maintaining section is adjusted based on a result of the measurement. The oxidizing material grinding system according to claim 6, 6 or 7.