WO2015019434A1 - Rare earth separation and recovery apparatus - Google Patents

Abstract

An apparatus for separating and recovering multiple kinds of rare earth elements, the apparatus being provided with: a first heating furnace for chlorinating a rare earth feedstock containing multiple kinds of rare earth elements; a second heating furnace for heating the chlorinated rare earth feedstock in an oxygen atmosphere; and a solid-liquid separation unit for mixing the rare earth feedstock, which has been heated in the oxygen atmosphere, with a solvent and separating the multiple kinds of rare earth elements from each other by solid-liquid separation. The first heating furnace and the second heating furnace are provided with atmosphere-exchanging devices at the inlets and outlets for the rare earth feedstock.

Description

Rare earth separation and recovery equipment

The present invention relates to an apparatus for separating and collecting a rare earth composition.

Rare earth elements are used in motors for hybrid automobiles and magnetic disk devices (so-called rare earth magnets), phosphors used in displays and lighting equipment, abrasives used for polishing glass, and amplifiers in optical communication equipment. The demand is expected to increase further in the future. On the other hand, in recent years, the price of rare earth materials has risen due to the uneven distribution of rare earth resources, and as a resource risk hedge, the use of rare earths, development of alternative materials, and separation and recovery of rare earth elements from products The method to do is examined.

As a method for separating and recovering rare earth elements, for example, Patent Document 1 describes separation using the solubility difference of Re sulfate.

JP 2010-285680 A

However, the method of Patent Document 1 uses a very high concentration of strong acid or highly volatile solvent, and thus has a problem of having a significant impact on the environment.

In the present invention, it is an object to reduce the influence on the environment when the rare earth component is separated and recovered.

To achieve the above object, the present invention provides an apparatus for separating and recovering a plurality of types of rare earth elements, a first heating furnace for chlorinating a rare earth material containing a plurality of types of rare earth elements, and the chlorinated rare earth material. A second heating furnace that heats in an oxygen atmosphere; and a solid-liquid separation unit that mixes the rare earth material heated in an oxygen atmosphere with a solvent to separate the plurality of rare earth elements from each other in a solid-liquid manner. The heating furnace and the second heating furnace include a device for switching an atmosphere between an inlet and an outlet of the rare earth material.

According to the present invention, the influence on the environment can be reduced during the separation and recovery of rare earth components.

Configuration diagram of separation device Schematic diagram of heat treatment process equipment

Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. In addition, this invention is not limited to embodiment taken up here, A combination and improvement are possible suitably in the range which does not change a summary.

Fig. 1 shows the block diagram of the separation device. The present embodiment is an apparatus for separating and recovering rare earth elements from a raw material containing a plurality of types of rare earth elements, and includes an apparatus for performing at least three steps of a raw material adjustment step 10, a heat treatment step 20, and a separation step 30. .

Here, the raw material adjustment step 10 includes devices such as a rare earth raw material supply unit 110, an ammonium chloride supply unit 120, a solvent supply unit 130, a mixing and grinding unit 140, a drying unit 150, and a molding unit 160. The heat treatment step 20 includes devices such as a gas supply unit 210, a heat treatment unit 220, an ammonium chloride recovery unit 230, a gas abatement unit 240, an ammonium chloride measurement unit 250, and an ammonium chloride recovery pipe 260. The separation step 30 includes devices such as a solvent supply unit 310, a solid-liquid separation unit 320, and a solid recovery unit 330.

When a powder containing a mixture of a raw material containing multiple types of rare earth elements and ammonium chloride is heated, each rare earth element generates a chloride. Thereafter, when the chloride is oxidized, an acid chloride is generated depending on the type of rare earth chloride. By stirring a mixture of rare earth chloride and rare earth acid chloride in a solvent such as water, it is divided into rare earth chloride that is easily soluble in the solvent and rare earth acid chloride that is hardly soluble in the solvent and easily precipitates. Separate and recover seed rare earth elements. In this embodiment, the raw material and ammonium chloride are mixed in the raw material adjustment step 10, the mixed powder is heated in the heat treatment step 20, and the rare earth chloride mixture is solid-liquid separated using a solvent in the separation step 30. According to this, rare earth elements can be separated and recovered without using a solvent with a large environmental load.

Hereinafter, the apparatus used in the heat treatment step 20 will be described in detail with reference to the drawings.

FIG. 2 shows a schematic diagram of an apparatus of the heat treatment unit 220. In FIG. 2, 210 is a gas supply unit, 221 is a buffer, 222 is a shutter, 223 is an evacuation device, 224 is a heating furnace, 225 is a transfer machine, 226 is a furnace body, 227 is a heating furnace, 228 is a heating furnace, 230 is an ammonium chloride recovery section, 231 is a solvent supply section, 240 is a gas abatement section, and 260 is an ammonium chloride recovery pipe.

The sample (mixed powder) supplied from the raw material adjustment step 10 is conveyed to the heating furnace 224 through the buffer 221. In the heating furnace 224, chlorination with ammonium chloride, which is the first step of heat treatment, is performed. The sample after the chlorination treatment is transported to the heating furnace 227 via the buffer 221 installed between the heating furnace 224 and the heating furnace 227. In the heating furnace 227, ammonium chloride removal, which is the second step of heat treatment, is performed. The sample after the ammonium dechlorination treatment is transported to the heating furnace 228 via a buffer 221 installed between the heating furnace 227 and the heating furnace 228. In the heating furnace 228, oxidation (acidification) treatment, which is a third step of heat treatment, is performed. The sample after the oxidation treatment is supplied to the separation step 30 via the buffer 221.

The buffer 221 is provided with shutters 222 at both ends (inlet side and outlet side). Further, the vacuum exhaust device 223 and the gas supply unit 210 are connected. Although it is necessary to change the atmosphere in the raw material adjustment process 10 and the heat treatment process 20, the atmosphere in the buffer can be controlled by the vacuum exhaust device 223, the gas supply unit 210, and the shutter 222. Further, by installing a heater in the buffer, the temperature in the buffer can be controlled together with the atmosphere. Furthermore, the moisture content in the atmosphere can be controlled by installing a dew point control device.

In this embodiment, by providing such a buffer, it is possible to switch the atmosphere between the raw material adjustment step and the heat treatment step, between the heat treatment step, and between the heat treatment step and the separation step.

In addition, by controlling the dew point of the gas supplied from the gas supply unit, the temperature in the buffer, the dew point, etc., and keeping the sample in the buffer in a dry atmosphere, moisture absorption from the outside air and atmosphere is prevented. be able to.

Examples of the structure of the heating furnace include a batch furnace method in which the sample is allowed to stand, a rotary kiln furnace method in which the sample is flowed and stirred, a fluidized bed furnace method, a tunnel furnace method having a mechanism for transporting the stationary sample, and the like. It can be appropriately selected according to the shape of the sample, the amount of sample treatment, the heat treatment conditions, the size, shape, mechanism, etc. of the heating furnace. The arrangement of the heating furnaces may not be alternately up and down.

In the case of a reaction between solids, the more the contact opportunity such as the contact time between solids and the contact area, the more the reaction is promoted. Therefore, a batch furnace method or a method of standing a sample such as a tunnel furnace method is preferable. In the case of a reaction between a solid and a gas, the reaction is accelerated if the solid is agitated to increase the chance of contact with the gas.Therefore, there is a method of flowing and stirring a sample such as a rotary kiln furnace method or a fluidized bed furnace method. preferable.

In this embodiment, since a plurality of heat treatment steps are performed using a plurality of heating furnaces, when these are continuously performed, it is preferable that a transporter 225 for transporting the sample is installed in the heating furnace.

The heating source of the heating furnace includes electricity, LP gas, heavy oil, etc., which can be appropriately selected according to the sample processing amount, processing cost, environmental conditions (such as legal regulations) where the equipment is installed, etc. it can.

The heating method includes heat transfer heating with a heater, high frequency induction heating, far-infrared heating, microwave heating, etc., and should be appropriately selected according to the heat treatment conditions, the size, shape, mechanism, etc. of the heating furnace. Can do.

The furnace body 226 of the heating furnace includes metal materials excellent in oxidation resistance at high temperatures, such as SUS material, inconel material, Fe—Co alloy, Ni-base alloy, alumina, zirconia, silicon nitride, silicon carbide. Ceramic materials typified by quartz and the like are preferable, and can be appropriately selected according to the heat treatment conditions, the size, shape, mechanism, etc. of the heating furnace.

In the gas abatement part 240, the gas generated in the heat treatment process is rendered harmless and discharged out of the system. Examples of the abatement apparatus in the gas abatement section include a dry apparatus that uses an abatement cylinder, a combustion apparatus that burns gas, and a wet apparatus that uses treatment chemicals. In the present invention, an optimal apparatus can be appropriately selected according to the amount of gas generated, processing cost, and the installation environment (legal regulations, etc.) of the apparatus.

In the gas supply unit 210, an optimum gas is appropriately supplied according to the atmosphere of the buffer and the heat treatment conditions of the heating furnace.

When supplying a raw material sample from the raw material adjusting step 10, first, the shutter 222 on the inlet side of the buffer 221 is opened, the shutter 222 on the outlet side is closed, and the sample is conveyed into the buffer 221. After transporting the sample into the buffer and closing the shutter 222 on the inlet side, the inside of the buffer is evacuated by the evacuation device 223. After the pressure is reduced to a predetermined pressure, the same atmospheric gas as that of the heating furnace 224 is supplied from the gas supply unit 210 into the buffer. After the buffer is filled with a gas having a predetermined atmosphere and pressure, only the shutter 222 on the outlet side is opened, and the sample is conveyed to the heating furnace 224. After transporting the sample, the shutter 222 on the exit side is closed. In the following buffers, samples are taken in and out through the same procedure.

In the heating furnace 224, an inert gas such as argon gas or nitrogen is preferably supplied from the gas supply unit 210 in order to perform chlorination using ammonium chloride, which is the first step of the heat treatment. Further, at this time, it is preferable to use a so-called dry gas having a low water content with a gas dew point temperature of −60 ° C. or less. This is because when the water content is low, the desired chloride is easily generated. The gas generated by the heat treatment in the heating furnace 224 is discharged out of the system through the gas abatement part 240.

The sample heat-treated in the heating furnace 224 is transported to the heating furnace 227 via the buffer 221 installed between the heating furnace 224 and the heating furnace 227. In the heating furnace 227, in order to perform the deammonium treatment, which is the second step of the heat treatment, it is preferable to carry out the treatment in a reduced pressure exhaust atmosphere. An inert gas such as argon gas or nitrogen can be supplied from the supply unit. In this case as well, it is preferable to use a gas having a low dew point as described above. The heat-treated sample is transported to a buffer 221 installed between the heating furnace 227 and the heating furnace 228.

In the heating furnace 227, ammonium chloride is generated with the dechlorination ammonium treatment. The generated ammonium chloride is recovered by the ammonium chloride recovery unit 230. The ammonium chloride recovery unit maintains the temperature, atmosphere, and pressure at which ammonium chloride generated as a gas in the heating furnace 227 is solidified, and recovers ammonium chloride in a solid powder state. The recovered ammonium chloride is transported to the raw material adjustment step 10 through the ammonium chloride recovery pipe 260 and reused as the raw material.

It is also possible to provide a solvent supply unit 231 in the ammonium chloride recovery unit 230, add a solvent to the recovered ammonium chloride, and recover the ammonium chloride in a solution state dissolved in the solvent. This ammonium chloride in the solution state is preferable because it can be easily recovered from the container as compared with the powder state. Moreover, since the conveyance to the raw material adjustment process 10 becomes easier than the case of a powder state, it is more preferable. Water can be used as the solvent, but is not limited thereto.

When supplying the recovered powder or solution ammonium chloride recovered by the ammonium chloride recovery unit 230 to the raw material adjustment step 10, an ammonium chloride measuring unit 250 is provided during this period to determine the amount and purity of the recovered ammonium chloride. It is preferable to measure. In FIG. 1, the ammonium chloride recovery pipe 260 is connected to the ammonium chloride supply unit 120, but may be connected to a pipe on the way to the mixing and grinding unit 140.

As a method for measuring the purity of the recovered ammonium chloride, fluorescent X-ray analysis, energy dispersive X-ray spectroscopy, inductively coupled plasma spectroscopy, atomic absorption spectroscopy, X-ray diffraction, etc. can be used. It is not limited to.

When the second heat treatment step is performed in the same atmosphere as the first step, it is possible to use the same heating furnace for the first step and the second step. In this case, use the heating furnace 224. First, the raw material supplied from the raw material adjustment step 10 can be supplied to the heating furnace 227 via a buffer, and the first step and the second step can be performed continuously in the heating furnace 227.

The sample processed in the heating furnace 227 is transported to the heating furnace 228 via the buffer 221 installed between the heating furnace 227 and the heating furnace 228. In the heating furnace 228, oxygen-containing gas is supplied in order to perform chloride acidification, which is the third step of heat treatment. The ratio of oxygen contained in the gas and the amount of moisture (dew point) contained in the gas can be appropriately selected as appropriate in accordance with the target rare earth component and the amount of heat treatment. There may be a chlorination reaction and an oxidation reaction. Note that the gas generated by the heat treatment in the heating furnace 228 is discharged out of the system through the gas abatement part 240 as described above.

Hereinafter, specific examples will be described.

Neodymium oxide (Nd ₂ O ₃ ) and dysprosium oxide (Dy ₂ O ₃ ) were used as rare earth materials. Ammonium chloride was mixed so that the amount of ammonium chloride was 15 mol with respect to 1 mol of the mixed powder mixed so that Dy / Nd was 1/7 by weight.

This mixed powder was supplied to the buffer 1 installed in the front stage of the heating furnace in the first step. In buffer 1, the vacuum pump is evacuated to about 20 Pa with a rotary pump, and after the vacuum evacuation-gas introduction operation for introducing argon gas with a dew point of −70 ° C. is repeated five times, the mixed powder is supplied from buffer 1 to the heating furnace in the first step. did.

In the first step, heat treatment is performed at 300 ° C. for 5 hours while flowing the argon gas at a flow rate of 500 mL / min using a rotary kiln furnace in which the argon gas atmosphere is made of Inconel. A mixture of chloride and Dy chloride was formed. This mixture was conveyed to the buffer 2 installed between the heating furnace of the first step and the heating furnace of the second step.

In this buffer 2, the same vacuum exhaust-gas introduction operation as described above was performed once. Then, the mixture was supplied to the heating furnace of the second step. In the second step, the ammonium chloride treatment was performed under the conditions of 400 ° C. and 4 hours while evacuating with a rotary pump using a rotary kiln furnace made of Inconel as the furnace body. The mixture after ammonium dechlorination treatment was conveyed to the buffer 3 installed between the heating furnace in the second step and the heating furnace in the third step. The recovered ammonium chloride was dissolved in water in the ammonium chloride recovery section, supplied to the raw material adjustment step in a solution state, and reused.

In this buffer 3, the same vacuum exhaust-gas introduction operation as described above was performed 5 times using dry air having a dew point of −60 ° C. Then, the mixture was supplied to the heating furnace in the third step. The third step was a dry air atmosphere. Using a rotary kiln furnace having a furnace body made of Inconel, heat treatment was performed at 350 ° C. for 5 hours while flowing dry air at a flow rate of 500 mL / min to produce a mixture of Dy acid chloride and Nd chloride. The mixture after the oxidation treatment was recovered and then supplied to the separation step.

The separation process was performed using pure water in the separation step. Since Nd chloride is easily dissolved and Dy acid chloride is easily precipitated, the Dy separation rate is 90% and the recovery rate is 90%, and a sufficient separation rate and recovery rate are obtained even in one step.

Cerium oxide (Ce ₂ O ₃ ) and lanthanum oxide (La ₂ O ₃ ) were used as rare earth materials. Ammonium chloride was mixed so that the amount of ammonium chloride was 12 mol with respect to 1 mol of the mixed powder mixed so that Ce / La was 1/1 by weight ratio.

This mixed powder was supplied to the buffer 1 installed in the front stage of the heating furnace in the first step. In buffer 1, after evacuating to about 20 Pa with a rotary pump, the evacuation-gas introduction operation of introducing dry nitrogen gas having a dew point of −60 ° C. was repeated five times, and then the mixed powder was transferred from buffer 1 to the heating furnace in the first step. Supplied.

In the first step, using a batch furnace using an alumina-based heat insulating material as the furnace body in the nitrogen gas atmosphere, while flowing the nitrogen gas at a flow rate of 1000 mL / min, conditions of 350 ° C. and 3 hours And a mixture of Ce chloride and La chloride was formed. This mixture was conveyed to the buffer 2 installed between the heating furnace of the first step and the heating furnace of the second step.

In this buffer 2, the same vacuum exhaust-gas introduction operation as described above was performed once. Then, the mixture was supplied to the heating furnace of the second step. In the second step, an ammonium chloride treatment was performed at 450 ° C. for 2 hours using a rotary kiln furnace having an inconel as the furnace body while evacuating with a rotary pump. The mixture after ammonium dechlorination treatment was conveyed to the buffer 3 installed between the heating furnace in the second step and the heating furnace in the third step. The recovered ammonium chloride was recovered in a powder state in the ammonium chloride recovery section, and then supplied to the raw material adjustment step for reuse.

In this buffer 3, the same vacuum exhaust-gas introduction operation as described above was performed 5 times using dry air having a dew point of −60 ° C. Thereafter, the sample was supplied to the heating furnace in the third step. The third step was a dry air atmosphere. Using a rotary kiln furnace made of quartz as the furnace body, heat treatment was carried out at 250 ° C. for 5 hours while flowing dry air at a flow rate of 500 mL / min to produce a mixture of Ce acid chloride and La chloride. The mixture after the oxidation treatment was recovered and then supplied to the separation step.

When the mixture after the oxidation treatment was separated using pure water in the separation step in the same manner as in Example 1, a result with a Ce separation rate of 93% and a recovery rate of 91% was obtained.

Neodymium oxide (Nd ₂ O ₃ ) and dysprosium oxide (Dy ₂ O ₃ ) were used as rare earth materials. Ammonium chloride was mixed so that the amount of ammonium chloride was 18 mol with respect to 1 mol of the mixed powder mixed so that Dy / Nd was 1/1 by weight ratio.

This mixed powder was supplied to the buffer 2 installed in the front stage of the heating furnace in the second step. In buffer 2, after evacuating to about 20 Pa with a rotary pump, the evacuation-gas introduction operation for introducing dry nitrogen gas having a dew point of −60 ° C. was repeated five times, and the mixed powder was transferred from buffer 2 to the heating furnace in the second step. Supplied.

In the first step, heat treatment is performed at 300 ° C. for 5 hours while flowing the nitrogen gas at a flow rate of 500 mL / min using a rotary kiln furnace in which the furnace body is made of SUS material. A mixture of Nd chloride and Dy chloride was formed.

Subsequently, the dechlorination treatment in the second step was performed at 400 ° C. for 6 hours while flowing the nitrogen gas at a flow rate of 500 mL / min.

The mixture after the dechlorination ammonium treatment was transported to the buffer 3 installed between the heating furnace in the second step and the heating furnace in the third step. The recovered ammonium chloride was dissolved in water in the ammonium chloride recovery section, supplied to the raw material adjustment step in a solution state, and reused.

In this buffer 3, the same vacuum exhaust-gas introduction operation as described above was performed 5 times using dry air having a dew point of −60 ° C.

Thereafter, the mixture was supplied to the heating furnace in the third step. The third step was a dry air atmosphere. Using a rotary kiln furnace whose furnace body is made of SUS material, heat treatment was performed at 300 ° C. for 3 hours while flowing dry air at a flow rate of 500 mL / min, and a mixture of Dy acid chloride and Nd chloride was generated. .

When the mixture after the oxidation treatment was separated using pure water in the separation step, a result with a Dy separation rate of 95% and a recovery rate of 93% was obtained.

10 Raw material adjustment process
20 Heat treatment process
30 Separation process
110 Rare Earth Material Supply Department
120 Ammonium chloride supply section
130 Solvent supply section
140 Mixing and grinding section
150 Drying section
160 Molding part
210 Gas supply unit
220 Heat treatment section
221 Buffer
222 Shutter
223 Vacuum exhaust system
224 Heating furnace
225 Transporter
226 Furnace
227 Heating furnace
228 Heating furnace
230 Ammonium chloride recovery section
231 Solvent supply unit
240 Gas abatement part
250 Ammonium chloride measuring unit
260 Ammonium chloride recovery piping
310 Solvent supply unit
320 Solid-liquid separator
330 Solid recovery unit

Claims (9)

In an apparatus for separating and collecting a plurality of types of rare earth elements, a first heating furnace for chlorinating a rare earth material containing a plurality of types of rare earth elements, and a second heating furnace for heating the chlorinated rare earth material in an oxygen atmosphere; The first heating furnace and the second heating furnace include a solid-liquid separation unit that mixes the rare earth material heated in an oxygen atmosphere with a solvent and separates the plurality of rare earth elements from each other. A rare earth separation and recovery device comprising a device for switching the atmosphere between the inlet and the outlet of the rare earth material. 2. The apparatus according to claim 1, wherein the atmosphere switching device includes a buffer, an openable / closable shutter provided at an inlet and an outlet of the buffer, a vacuum exhaust device connected to the buffer, and a gas supply unit. Rare earth separation and recovery equipment. 2. The rare earth separation and recovery device according to claim 1, wherein the rare earth material is salified with ammonium chloride. The third heating furnace according to claim 3, further comprising a third heating furnace that generates ammonium chloride by heating the chlorinated rare earth material between the first heating furnace and the second heating furnace. Rare earth separation and recovery equipment. The ammonium chloride supply unit for supplying the ammonium chloride according to claim 4, wherein the ammonium chloride generated in the third heating furnace is chlorinated between the ammonium chloride supply unit and the third heating furnace. A rare earth separation and recovery device comprising an ammonium chloride recovery pipe for recovery in an ammonium supply section. 6. The method according to claim 5, further comprising: an ammonium chloride recovery unit that recovers ammonium chloride generated in the third heating furnace; and a shutter that can open and close a space that communicates with the third heating furnace and the ammonium chloride recovery unit. One end of the ammonium chloride recovery pipe is connected to the ammonium chloride recovery unit. 7. The rare earth separation and recovery device according to claim 6, further comprising a solvent supply unit connected to the ammonium chloride recovery unit. 2. The rare earth separation and recovery device according to claim 1, wherein at least one of the first heating furnace and the second heating furnace is a rotary kiln. 2. The rare earth separation and recovery device according to claim 1, further comprising a transporter configured to transport the rare earth material to at least one of the first heating furnace and the second heating furnace.

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