JP2014185373A - Removal device for rare earth impurities in nickel electroplating solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device which removes relatively easily and efficiently rare earth impurities dissolved in the plating solution in plating a rare earth magnet because ingredients of the rare earth magnet dissolve in the plating solution and becomes a possible cause for poor plating.SOLUTION: Rare earth impurities are precipitated by warming a nickel electroplating solution containing dissolved rare earth impurities by the warming means 7 in a plating tank provided with warming means 7, cooling means 8 and separation removal means 9. After the warmed plating solution is cooled to a temperature for plating treatment by the cooling means 8, the plating solution after separation removal of the precipitation of rare earth impurities by the separation removal means 9 is circulated, while the concentration of the impurities in the plating solution in the plating tank is decreased.

Description

  The present invention relates to a removal apparatus for removing rare earth impurities in an electronickel plating solution.

Among rare earth magnets, R—Fe—B based sintered magnets (R is at least one of rare earth elements including Y and necessarily contains Nd) have high magnetic properties and are widely used. Nd and Fe contained as main components are very rusting. For this reason, a rust preventive film is given to the magnet surface for the purpose of improving corrosion resistance. In particular, electronickel plating has high hardness, and the management of the plating process is simpler than electroless plating, and is widely adopted for this magnet.
In the very initial stage of the growth process of the plating film by the electro nickel plating, the components of the object to be plated may be dissolved in the plating solution simultaneously with the film formation.
In particular, when the pH of the plating solution is inclined to the acidic side or when the object to be plated is easily dissolved in the plating solution, the object to be plated dissolves in the plating solution and accumulates as impurities in the plating solution.
In the case of an R—Fe—B based sintered magnet, a rare earth element such as Nd, which is a main component, or Fe dissolves in the plating solution and becomes an impurity.
Therefore, when the plating process is continuously performed, rare earth impurities such as Nd and Fe, which are main components of the magnet material, are dissolved and accumulated in the plating solution. In order to perform plating without impurities, it is necessary to build a new plating solution for each plating process. In the manufacturing process, it is difficult to build a new plating solution for each plating process because the cost increases. It is virtually impossible.

In the case of electro-nickel plating, generally, if an impurity is contained in the plating solution, a change in gloss, poor adhesion with the object to be plated, or burn (burn) is likely to occur.
For example, if a rare earth element accumulates as an impurity in the plating solution and exceeds a certain amount, adhesion between the plating film and the magnet material decreases, causing peeling, or current interruption during plating film formation. Double plating which is in-layer peeling occurs.
Whether or not a defect such as double plating occurs due to a decrease in adhesion depends on the composition of the plating solution and the plating conditions. According to the experiments by the present inventors, when the amount of rare earth impurities exceeds 700 ppm (mainly Nd impurities). It tends to occur. Furthermore, it has also been confirmed that the plating by the barrel method is likely to cause double plating because a large current flows locally to the object to be plated.
Maintaining the absence of rare earth impurities in the electronickel plating solution when performing electronickel plating on an industrial mass production scale is impractical from the viewpoint of manufacturing cost and is generally adopted. Absent. However, from the viewpoint of quality control, the amount of rare earth impurities does not exceed 700 ppm, and it is desirable to manage it low.

As a method of removing impurities such as Fe dissolved in the electric nickel plating solution, a nickel compound such as nickel carbonate is added to the plating solution, and the pH of the plating solution is increased (at the same time, activated carbon is added to remove organic impurities). In some cases, impurities are precipitated by further agitation with air, followed by filtration, or by immersing an iron net or plate in the plating solution and cathodic electrolysis at a low current density. ing.
These methods are effective as a method for removing impurities of iron and organic matter dissolved in the electro nickel plating solution, but it is extremely difficult to remove rare earth impurities.
Patent Document 1 discloses a method and apparatus for removing rare earth impurities from an electronickel plating solution using a chemical used for purification and separation of rare earth metals.
This method is considered to be effective as one of the methods for reducing rare earth impurities in the electronickel plating solution.
However, in order to realize this method, it is necessary to employ a complicated process, which is not efficient, and a special drug is required. For this reason, the operation of the apparatus is complicated and the configuration is inevitably complicated.

Japanese Patent Laid-Open No. 7-62600

  An object of the present invention is to provide a removal device that has a relatively simple structure, has good operability, is relatively simple and can efficiently remove rare earth impurities in an electronickel plating solution.

The present invention according to claim 1 is an apparatus for removing rare earth impurities in an electronickel plating solution, which is a heating means for heating an electronickel plating solution containing rare earth impurities, and is deposited by heating by the heating means. And a separation / removal means for separating and removing the precipitate from the electrolytic nickel plating solution cooled by the cooling means.
According to the second aspect of the present invention, the heating means can heat the electro nickel plating solution containing the rare earth impurities to 80 ° C. or more, and the cooling means is heated by the heating means. The removal apparatus according to claim 1, wherein the electrolytic nickel plating solution containing the precipitate can be cooled to a temperature before heating.
The present invention described in claim 3 is characterized in that the heating means is a heating heater or a heating heat exchanger, and the cooling means is a cooling pipe or a cooling heat exchanger. Item 3. The removing device according to Item 1 or 2.
The present invention described in claim 4 is the removing apparatus according to any one of claims 1 to 3, wherein the separation and removal means is a filter or a sedimentation tank.
The present invention described in claim 5 is characterized in that the heating means, the cooling means, and the separation and removal means are connected to a liquid storage tank for storing an electro nickel plating solution containing rare earth impurities via the heating means. It is a removal apparatus in any one of Claims 1-4 characterized by the above-mentioned.
The present invention described in claim 6 is connected so that the liquid storage tank is a plating tank, and the electrolytic nickel plating liquid from which the precipitate is removed by the separation and removal means can be returned to the plating tank. The removal apparatus according to claim 5.
In the present invention described in claim 7, a pump is disposed between the plating tank and the heating means as a moving means for moving the electro nickel plating solution containing rare earth impurities stored in the plating tank to the heating means. The removal apparatus according to claim 6, wherein

  According to the present invention, it is possible to provide a device for removing rare earth impurities in an electronickel plating solution that has a relatively simple configuration and good operability. Therefore, it can be removed relatively easily and efficiently without employing a simple process and without using a special drug. For this reason, it is possible to achieve the stabilization of the quality of electro nickel plating and the cost reduction especially for the R—Fe—B based sintered magnet. Furthermore, by adopting a configuration in which the electronickel plating solution from which the rare earth impurities (precipitates) are separated and removed is returned to the plating tank, the rare earth impurities can be removed continuously during the electronickel plating process, resulting in stable quality. It is possible to efficiently realize the plated process.

It is a schematic diagram which shows an example of the electro nickel plating apparatus containing the removal apparatus which removes the rare earth impurities in the electro nickel plating liquid of this invention. It is an analysis result by the ICP emission spectrometer which shows the amount of Nd as a rare earth impurity in the plating solution after filtration. (When the temperature is changed) It is an analysis result by the ICP emission spectrometer which shows the amount of Nd as a rare earth impurity in the plating solution after filtration. (Change of heating retention time less than 24 hours)

The present invention relates to an apparatus for removing rare earth impurities in an electronickel plating solution, the heating means for heating the electronickel plating solution containing the rare earth impurities, and the electricity containing the precipitate deposited by the heating by the heating means. It is a removing device comprising cooling means for cooling the nickel plating solution, and separation / removal means for separating and removing the precipitate from the electric nickel plating solution cooled by the cooling means.

  In the present invention, the rare earth impurity is, for example, an electroplating solution for electro-nickel plating of an R—Fe—B based sintered magnet (R is at least one of rare earth elements including Y and must contain Nd). In the plating solution, most of it is in an ionic state, so that it is difficult to collect by filtration as it is. The removal apparatus of the present invention is a heating means for heating a plating solution to deposit rare earth impurities present in an ionic state as solid precipitates that can be collected by a known separation and removal means such as a filter. Is an essential configuration. In addition to separation / removal means for separating and removing the precipitate from the plating solution by sedimentation or filtration, cooling for cooling the plating solution containing the precipitate heated by the heating means in order to efficiently perform the separation / removal. The means is an essential component. The removal device of the present invention is not limited to the removal of the R component dissolved in the plating solution when electroplating the R-Fe-B sintered magnet, but similarly, the removal of ions in the plating solution It can be applied in the removal of rare earth impurities present in the state.

The heating means constituting the removal apparatus of the present invention may be heated to a temperature at which rare earth impurities present in an ionic state in the plating solution can be deposited as precipitates that can be collected by the separation and removal means. A means having a structure capable of adjusting the heating temperature of the plating solution in accordance with the composition and amount of the plating solution, the amount of rare earth impurities in the plating solution, the required treatment time, and the like is desirable.
According to the experiment of the present inventor, usually, if heating at 60 ° C. or higher is possible, the precipitate can be deposited. In order to utilize it more effectively on an industrial scale, it is desirable to select a heating means capable of heating a plating solution containing rare earth impurities to 80 ° C. or higher. The higher the heating temperature, the higher the removal efficiency of rare earth impurities (precipitation efficiency of precipitates). The upper limit is not particularly limited, but from the viewpoint of workability and safety, the composition of the plating solution It is desirable that the temperature be lower than the boiling point of the plating solution because of its influence on the surface.
When the plating solution is heated to a boiling point or higher, water is rapidly evaporated from the plating solution, and components constituting the plating solution are rapidly precipitated. The boiling point of the plating solution varies depending on the composition. For example, the boiling point of the watt bath is about 102 ° C.
As described above, since the boiling point of the plating solution rises due to an increase in the molar boiling point, if the upper limit is 100 ° C., which is the boiling point of water, it is possible to cope with the removal of impurities from plating solutions having different compositions.

As specific heating means for realizing the above heating, a heating heater, a heating heat exchanger, or the like can be employed. Using such a heating means, the electronickel plating solution containing rare earth impurities is heated to 60 ° C. or higher, and further heated to a range of 80 ° C. to 100 ° C., more preferably 90 ° C. to 95 ° C. This makes it possible to efficiently remove the target rare earth impurities.
In addition, in each member which comprises the removal apparatus of this invention, since it is necessary to use a thing with high heat resistance according to the said heating range (temperature of the plating solution by heating), this temperature is The higher the cost, the higher the overall cost of the apparatus. Implementing in the above-mentioned heating temperature range, particularly a desirable heating temperature range, contributes to the suppression of the cost increase of the apparatus as a result.

In order to promote precipitation of precipitates during the heating, it is desirable to stir the plating solution in a warmed state, and it is desirable to install a known stirrer attached to the warming means.
For example, the thing of the structure which implement | achieves sales expansion by air stirring, rotation of a stirring blade, or circulation with a pump is employ | adopted.

It is desirable that the plating solution is cooled to the above temperature and then cooled before separating (removing) the precipitates (rare earth impurities). That is, handling of the plating solution is not only complicated, but if the plating solution which has been heated is passed through a separation and removal means, for example, a filter of a filter, the life of the filter is extremely shortened, or in some cases the filter is There is a risk that the intended efficient removal of rare earth impurities cannot be achieved.
In addition, after filtering the heated plating solution (after removing the precipitate) and returning it to the plating tank without cooling, the high temperature plating solution is mixed with the plating solution in the plating process at the temperature before heating. Thus, the temperature of the plating solution during the plating process increases. It is not desirable from the viewpoint of the efficiency of the plating process to stop the plating process until the temperature of the entire plating solution returns to the temperature before heating.
Therefore, the cooling means constituting the removal apparatus of the present invention considers the influence on the separation and removal means as described above, the influence on the plating solution during the plating process when returning to the plating tank after the removal of precipitates, It is possible to adjust the cooling temperature, and it is desirable to select a means capable of cooling to a temperature before heating (substantially the same temperature as that during the plating process).
As specific cooling means for realizing the above cooling, a cooling pipe, a heat exchanger for cooling, or the like can be employed.

Note that the plating tank usually has an automatic adjustment function that automatically turns the heater on and off based on the temperature measurement result of the plating solution by a thermometer. The temperature after cooling the heated plating solution is Even if the temperature is higher or lower than the temperature before heating, there is no practical problem as long as the temperature is within the set plating temperature range with this automatic adjustment function.

  The separation / removal means constituting the removal apparatus of the present invention is only required to separate and remove the precipitate deposited by the heating means, such as the size of the precipitate, the amount of the precipitate, the amount of the plating solution to be treated, etc. It is desirable to select according to the above, and as a specific separation and removal means, a known filter, a sedimentation tank or the like can be used.

The removal apparatus of the present invention comprises the above-mentioned heating means, cooling means, and separation / removal means. In order to efficiently move the plating solution between these means, each means is usually connected by piping. And integrate. In order to move the plating solution more smoothly, it is desirable to provide moving means such as a pump at a predetermined location (for example, between each means).

The removal apparatus of the present invention can employ a configuration in which a storage tank for storing an electronickel plating solution containing rare earth impurities is connected to the heating means, the cooling means, and the separation and removal means via the heating means. . The plating solution containing a large amount of rare earth impurities used for a long time is once transferred from the plating tank being plated to the above storage tank, and the plating liquid in this storage tank is heated and cooled as described above. The rare earth impurities (precipitates) can be removed sequentially through the separation and removal means. If necessary, a storage tank for storing plating solution (plating solution from which rare earth impurities are removed) other than the above storage tank is connected to the separation / removal means, and the storage tank is filled with rare earth. It becomes possible to store the plating solution from which impurities have been removed for a necessary time.
In this configuration, during and after the removal of rare earth impurities, there is no effect on the plating solution during the plating process, and the temperature adjustment and composition adjustment of the plating solution from which the rare earth impurities have been removed are also described above. The effect that it can carry out easily in a liquid storage tank etc. is realizable.

Furthermore, the removal apparatus of the present invention uses an electrolytic nickel plating solution in which the electrolytic nickel plating solution containing rare earth impurities is stored through the heating means as a plating tank, and the precipitate is removed by the separation and removal means. The structure which connects so that it can return to the said plating tank is employable. By adopting this configuration, the rare earth impurities in the plating solution can be most efficiently removed. That is, removing (moving) the plating solution from the plating tank during the plating process → heating the plating solution by the heating means → cooling the plating solution by the cooling means → separation and removal of precipitates (rare earth impurities) by the separation / removal means ( Filtration) → Plating solution from which precipitates have been separated and removed (filtered) can be moved continuously (liquid feeding) to the plating tank.
In the above configuration, it is effective not only to connect the plating tank, heating means, cooling means, and separation / removal means by piping, but also to connect piping for returning the plating solution that has passed through the separation / removal means to the plating tank. It is. In order to perform continuous treatment with such an apparatus, as described above, when the plating solution is cooled by the cooling means, the plating solution once heated by the heating means is reduced to the temperature before heating. By cooling, it is desirable to suppress changes in plating conditions and prevent changes in the properties of the resulting plating film.
If the said apparatus is used, the increase of the rare earth impurities during a plating process can be suppressed by removing a rare earth impurity continuously. Therefore, as in the configuration described above, there is no need to transfer the plating solution to another storage tank other than the plating tank to remove the rare earth impurities, and to take steps such as removing the rare earth impurities, and the plating process. There is no need to stop.
In addition to the continuous treatment, even if the plating treatment is stopped as necessary and the plating solution is transferred to another storage tank to remove the rare earth impurities, the frequency of the rare earth impurities is suppressed, so the frequency is reduced. This is desirable because it leads to improved productivity.

In removing the rare earth impurities with the removing apparatus of the present invention, it is desirable that the concentration of the plating solution is the same (1 time) as the concentration for performing the plating treatment.
When moisture evaporates during heating and the concentration of the plating solution increases, it is desirable to replenish water appropriately to maintain the concentration.

The removal apparatus of the present invention can be suitably applied to the removal of rare earth impurities in acidic to neutral nickel plating solutions. The nickel plating solution can be applied to a watt bath, a high chloride bath, a chloride bath, a sulfamic acid bath, or the like.
The removal apparatus of the present invention is most suitably applicable to a watt bath.
As the liquid composition of the Watt bath, a very common bath composition may be used. For example, nickel sulfate 200 to 320 g / L, nickel chloride 40 to 50 g / liter, boric acid 30 to 45 g / L As an additive, the present invention can also be applied to compositions containing brighteners and pit inhibitors.
In order to effectively use the removal apparatus of the present invention, it is desirable to adjust the composition of the plating solution as needed by a known analysis method (such as titration analysis).
For example, in the case of a watt bath, nickel chloride and total nickel are analyzed by titration to obtain nickel sulfate, and boric acid is further analyzed by titration.
The composition of the plating solution obtained after removing the rare earth impurities obtained by the removing apparatus of the present invention is almost the same as the composition at the start of the plating process, and therefore the change in the composition of the plating bath due to the removal of the rare earth impurities is slight. .
Therefore, the composition of the plating solution in the plating tank may be analyzed by determining a certain period. What is necessary is just to set an analysis period suitably with the structure and production amount of a plating tank.
If the composition of the plating solution is within the control range as a result of analysis, it is not always necessary to add it, but if it is insufficient, an insufficient amount of nickel sulfate, nickel chloride, boric acid is added to the plating solution. Adjust the composition.
When adding, it is desirable to warm the plating solution to the plating temperature. When the temperature is low, dissolution of the added drug is slow or does not dissolve. Thereafter, the pH is adjusted with nickel carbonate or sulfuric acid, and a known brightener or pit inhibitor is added to perform plating.
What is necessary is just to set suitably about the plating conditions using the plating solution after applying the removal apparatus of this invention according to the equipment to be used, the plating method, the size of the object to be plated, the number of treatments, and the like.
As an example, the plating conditions when the plating bath having the above Watt bath composition is used are preferably pH 3.8 to 4.5, bath temperature 45 ° C. to 55 ° C., and current density 0.1 to 10 A / dm ² .
As a plating method, there are a rack method and a barrel method, which may be appropriately selected depending on the size of the object to be plated and the processing amount.

  What is necessary is just to use the material suitable for the composition and temperature of the plating solution to process as a liquid storage tank and a plating tank connected to the removal apparatus of this invention. In addition, safety | security can also be improved by using the container of a material with high heat resistance for a plating tank.

Below, the specific structure of the removal apparatus of this invention is demonstrated based on FIG. FIG. 1 shows a configuration that can most effectively realize the effect of the removal apparatus of the present invention, that is, a typical configuration that enables continuous processing by connecting to the plating tank described above. The present invention is not limited to the configuration shown in FIG.
In the figure, reference numeral 4 denotes a plating tank, which has an anode plate, a cathode, a heater, and a stirrer (not shown), and can build up a plating solution and perform electro nickel plating.
The material of the plating tank depends on the plating solution used, but vinyl chloride (PVC) or heat-resistant vinyl chloride (PVC) is desirable.
The arrow in the figure indicates the direction in which the plating solution flows.
In the figure, reference numeral 20 denotes a plating solution filtration system for plating. This filtration system 20 is installed for the purpose of filtering dust and the like floating in the plating solution, and deposits rare earth impurities present in an ionic state in the plating solution targeted by the present invention as precipitates. Cannot be separated and removed.
In the figure, 3 is a valve, 2 is a pump, and 1 is a filter. The plating solution flows in the order of plating tank 4 → valve 3 → pump 2 → filter 1 → plating tank 4, and as described above, Filter floating dust.
In the figure, reference numeral 30 denotes an impurity removal system for removing rare earth impurities present in an ionic state in the plating solution including the removal apparatus of the present invention.
In the figure, 5 is a valve, 6 is a pump as a moving means, 7 is a heat exchanger for heating as a heating means, 8 is a heat exchanger for cooling as a cooling means, 9 is a filter as a separation and removal means, 10 is a valve, and the plating solution flows in the order of plating tank 4 → valve 5 → pump 6 → heating heat exchanger 7 → cooling heat exchanger 8 → filter 9 → valve 10 → plating tank 4 in order. After the rare earth impurities dissolved in the liquid are deposited, they can be separated and removed by filtration.

When separating and removing the deposit from the plating solution, a sedimentation tank is provided instead of a filter as a separation and removal means, and the precipitate is settled and only the supernatant of the plating solution is continuously collected, and the deposit is separated and removed. May be.
In this case, a very small amount of precipitate floating in the sedimentation tank can be completely separated and removed by the filtration system 20 attached to the plating tank after being sent (moved) to the plating tank.
In the impurity removal system 30, the material of the pipes connecting the plating tank 4, the heating heat exchanger 7, the cooling heat exchanger 8, and the filter 9 may be appropriately set depending on the composition and temperature of the plating solution. However, since a high-temperature plating solution is allowed to flow through the piping connecting the heating heat exchanger 7 and the cooling heat exchanger 8, it is desirable to use one having high heat resistance.
It is desirable to use an iron pipe coated with PP or a fluororesin as a material having high heat resistance.
A known heat exchanger 7 can be used, and is not particularly limited, and an electric heater or steam can be selected as a heat source. A heat exchanger using steam is desirable because the plating solution can be easily heated.
A well-known thing can be used also about the heat exchanger 8 for cooling. As a refrigerant used for the heat exchanger 8 for cooling, a form using refrigerant gas may be used, or one using cold water may be used.

For the heating heat exchanger 7 and the cooling heat exchanger 8, the material in contact with the plating solution may be appropriately selected depending on the composition and temperature of the plating solution, but a material such as stainless steel or titanium having high corrosion resistance may be used. It is desirable to choose.
The type and capacity of the heat exchanger 7 for heating and the heat exchanger 8 for cooling are appropriately set according to the amount of plating solution to be heated and cooled (the capacity of the plating tank), the amount of products to be plated, the plating conditions, etc. Just do it.
For example, in FIG. 1, a configuration in which one path for the heat exchanger 7 for heating and one path for the heat exchanger 8 for cooling is employed, but two heat exchangers 7 for heating are arranged in series, Thereafter, two heat exchangers 8 for cooling are arranged in series, and one heat exchanger 7 for heating is used, and two sets are connected in parallel with one heat exchanger 8 for cooling as one set. A configuration may be adopted.
The flow rate of the plating solution flowing into the impurity removal system 30 is the capacity of the heat exchanger 7 for heating and the heat exchanger 8 for cooling, the capacity of the plating tank 4 (amount of plating solution), plating conditions, and the amount of products to be plated. What is necessary is just to set suitably by etc. The flow rate may be adjusted according to the capacity of the pump 6 to be used and the opening / closing amount of the valve 5.
Moreover, as a heating means, it may replace with said heat exchanger 7 for heating, and the thing of the structure which immersed the heating heater for heating in the predetermined | prescribed tank may be employ | adopted, and as a cooling means, Instead of the cooling heat exchanger 8, a structure in which a throwing-type cooling pipe is immersed in a predetermined tank may be adopted.
Here, the cooling pipe is a pipe that has been passed through a coolant or chilled water, and is poured into the plating solution via the heating means to cool the plating solution as well as the end that has been cooled by the Peltier effect, etc. This is a general term for cooling the plating solution by throwing in a cooling part that mainly constitutes cooling means into the plating solution, and cooling the plating solution.

In FIG. 1, the pump 6 that is the moving means is provided in one place in front of the heating heat exchanger 7 that is the heating means (between the plating tank 4 and the heating heat exchanger 7). If necessary, between the heating heat exchanger 7 as the heating means and the cooling heat exchanger 8 as the cooling means, between the cooling heat exchanger 8 and the filter 9 as the separation / removal means, or filtration It may be placed behind the vessel 9.
For example, when a cooling part of a heater or chiller is thrown into a container with an open top as a heating means or cooling means, or when a sedimentation tank with an open top is used as a separation and removal means, or a combination of these In this case, since there are many opening portions in the moving path of the plating solution, the pressure of the plating solution raised by the moving means decreases. Therefore, for the purpose of moving to the next means, it is desirable to provide a plurality of moving means in order to increase the pressure of the plating solution once lowered.
Further, when the flow rate of the plating solution moving between each means is large, it is desirable to adjust the flow rate by providing a valve or the like between these means.

  In the above, the removal apparatus having a configuration in which the respective means are connected by piping and the pump is employed as the plating solution moving means has been described, but the present invention is not limited to this configuration. For example, in addition to the plating tank, a tank equipped with a heating means, a tank equipped with a cooling means, and a tank equipped with a separation / removal means are sequentially provided with a height difference (the plating tank is the highest, and the separation / removal means is installed. By arranging the tank at the lowest position, the plating solution can be moved via each means without necessarily connecting pipes or adopting moving means such as a pump. However, even in the case of such a configuration, in order to carry out the continuous processing described above, the tank in which the separation / removal means is installed and the plating tank must be connected via a moving means such as a pump. desirable.

  In realizing the removal apparatus of the present invention, experiments shown in Experimental Examples 1 to 5 below were performed in advance, and the effects were confirmed.

Example 1
The plating solution composition is nickel sulfate 250 g / L, nickel chloride 50 g / L, boric acid 45 g / L, and a pH 4.5 plating solution is heated to 50 ° C., and electricity is applied to the surface of the R—Fe—B sintered magnet. Nickel plating was applied. R-Fe-B sintered magnets have Nd: 15 to 25 mass%, Pr: 4 to 7 mass%, Dy: 0 to 10 mass%, B: 0.6 mass% to 1.8 mass%, depending on the required magnetic properties. , Al: 0.07 to 1.2 mass%, balance Fe, and several types whose compositions were adjusted in the range of Cu and Ga of 3 mass% or less were used. However, the composition of the magnets used in one batch was the same.
The composition and amount of each rare earth impurity dissolved in the plating solution vary depending on the combination of magnets used for plating, the treatment method such as barrel plating and rack plating, and the composition of the plating solution.

After plating for several days, Nd impurities, Pr impurities, and Dy impurities in the electronickel plating solution were analyzed with an ICP emission analyzer.
The analysis results were Nd: 500 ppm, Pr: 179 ppm :, and Dy: 29 ppm.
The plating solution containing the rare earth impurities was collected in a fixed amount (3 liters) beaker and kept at a temperature of 90 ° C. with a heater for a fixed time. During heating, the mixture was stirred with a magnetic stirrer (magnet stirrer). During heating, water was replenished so that the concentration of the plating solution was constant.
After 24 hours and 96 hours, heating was stopped and cooled, and then a sufficient amount of plating solution was collected for ICP emission analysis, and Nd, Pr, The concentration of Dy was measured with an ICP emission spectrometer.
The analysis results after 24 hours were Nd: 100 ppm, Pr: 35 ppm, and Dy: 16 ppm.
The analysis results after 96 hours were Nd: 50 ppm, Pr: 16 ppm, and Dy: 2 ppm.
As described above, the ionic rare earth impurities dissolved in the electrolytic nickel plating solution become precipitates by heating for a predetermined time, and are separated and removed from the plating solution by filtration with filter paper. Rare earth impurities that have not become precipitates even after heating for a predetermined time remain in the plating solution in an ionic state at a rate as shown in the above analysis results. As is clear from the above analysis results, the longer the heating time, the greater the amount of rare earth impurities separated and removed as precipitates. As a result, the amount of rare earth impurities in the ionic state in the plating solution is reduced. The Rukoto.
It was found that the amount of impurities of Pr and Dy was reduced at the same time as the amount of impurities of Nd, which is a rare earth element, by the treatment method of Experimental Example 1.

Experimental example 2
The composition of the plating solution was 250 g / L of nickel sulfate, 50 g / L of nickel chloride, 45 g / L of boric acid, and a plating solution having a pH of 4.5 was heated to 50 ° C. to obtain an R—Fe—B sintered magnet (Example 1 and Electronickel plating was applied to the surface of the same composition range. After plating for several days, the Nd impurity in the electronickel plating solution was analyzed and found to be 576 ppm.
The above plating solution is set to 6 conditions with a heating temperature of 50 ° C. to 95 ° C. (however, 5 conditions in increments of 10 ° C. from 50 ° C. to 90 ° C.), and each sample is collected in a 3 liter beaker and added. Warm up. During heating, the mixture was stirred with a magnetic stirrer (magnet stirrer). While replenishing water so that the concentration of the plating solution remains constant during heating, collect a sufficient amount of the plating solution for ICP emission analysis at regular intervals, cool the collected plating solution and filter it with filter paper. The content (concentration) of Nd impurities in the plating solution was analyzed. An ICP emission analyzer was used for the analysis.
The analysis results are shown in Table 1 (results from 50 ° C. to 90 ° C.) and shown in the graph of FIG.

加温温度が５０℃では、１６８時間経過後で不純物濃度は５１８ｐｐｍとなった。６０℃では２４時間以降不純物濃度が低下し２１６時間経過後に１７７ｐｐｍとなった。不純物濃度は７０℃では６０℃に比較して２４時間以降常に低い傾向を示した。
加温温度が８０℃では、加温直後から不純物濃度は低下し、９６時間経過後に１２５ｐｐｍとなった。
加温温度が９０℃では、２４時間経過後で１３４ｐｐｍ、４８時間経過後で８４ｐｐｍとなり、９６時間経過後では５９ｐｐｍとなった。加温温度が９５℃では、２４時間経過後と９６時間経過後について分析した。Ｎｄ不純物量は９０℃で加温した場合とほぼ同じであった。
以上の結果からも明らかなように、加温温度が６０℃から明確な効果が確認され、８０℃、さらに９０℃においてその効果が一層顕著であることが確認された。

When the heating temperature was 50 ° C., the impurity concentration became 518 ppm after 168 hours. At 60 ° C., the impurity concentration decreased after 24 hours and became 177 ppm after 216 hours. The impurity concentration always tended to be lower after 24 hours at 70 ° C. than at 60 ° C.
When the heating temperature was 80 ° C., the impurity concentration decreased immediately after heating and became 125 ppm after 96 hours.
When the heating temperature was 90 ° C., it became 134 ppm after 24 hours, 84 ppm after 48 hours, and 59 ppm after 96 hours. When the heating temperature was 95 ° C., analysis was performed after 24 hours and after 96 hours. The amount of Nd impurities was almost the same as when heated at 90 ° C.
As is clear from the above results, a clear effect was confirmed from the heating temperature of 60 ° C., and it was confirmed that the effect was more remarkable at 80 ° C. and 90 ° C.

Experimental example 3
After cooling the plating solution heated in Experimental Example 1 and Experimental Example 2, the solution was filtered through filter paper, and the precipitate deposited from the plating solution was collected.
The precipitate was dried in a thermostatic bath. The property was powder (solid).
When the precipitate was analyzed with an energy dispersive X-ray analyzer (EDX),
Nd: 32.532, Pr: 11.967, Dy: 1.581, Al: 0.402, Ni: 7.986, C: 0.319, O: 45.213, (mass%).
It was confirmed that the rare earth impurities in the plating solution were precipitated as a powder (solid) from the plating solution by heating treatment.

Experimental Example 4
The composition of the plating solution was 250 g / L of nickel sulfate, 50 g / L of nickel chloride, 45 g / L of boric acid, and a plating solution having a pH of 4.5 was heated to 50 ° C. to obtain an R—Fe—B sintered magnet (Example 1 and Electronickel plating was applied to the surface of the same composition range. After plating for several days, the Nd impurity in the electronickel plating solution was analyzed and found to be 581 ppm.
The plating solution was collected in a 3 liter beaker and heated at 90 ° C.
During heating, the mixture was stirred with a magnetic stirrer (magnet stirrer). During heating, while supplying water so that the concentration of the plating solution becomes constant, the content of Nd impurity in the plating solution is 1, 3, 6, 12 and 24 hours in the same manner as in Experimental Example 1. (Concentration) was analyzed.
The analysis results are shown in Table 2 and shown in the graph of FIG.

９０℃での加温では、加温後３時間程度から顕著にNd不純物の低下が確認できた。

In heating at 90 ° C., a significant decrease in Nd impurities could be confirmed from about 3 hours after heating.

Experimental Example 5
The re-dissolution of rare earth impurities once deposited was investigated.
The composition of the plating solution was 250 g / L of nickel sulfate, 50 g / L of nickel chloride, 45 g / L of boric acid, and a plating solution having a pH of 4.5 was heated to 50 ° C. Electronickel plating was applied to the surface of the same composition range. After plating for several days, the Nd impurity in the electronickel plating solution was analyzed and found to be 544 ppm. The plating solution was collected in a 3 liter beaker and heated to 90 ° C.
During heating, the mixture was stirred with a magnetic stirrer (magnet stirrer). During heating, water was replenished so that the concentration of the plating solution was constant. After a certain time, a sufficient amount of the plating solution for ICP emission analysis was collected, the collected plating solution was cooled and filtered with a filter paper, and then the content (concentration) of Nd impurities in the plating solution was analyzed. An ICP emission analyzer was used for the analysis.
Moreover, after collecting a plating solution, the analysis result at the time of cooling a plating solution to 40 degreeC and hold | maintaining at 40 degreeC is shown below.
At 1, 3, 6, 24, and 48 hours after holding at 40 ° C, a sufficient amount of plating solution is collected for ICP emission analysis. After filtration, the content (concentration) of Nd impurities in the plating solution is analyzed. did.
The analysis results are shown in Table 3.

０ｈｒは９０℃にて採取しためっき液の分析値である。上記に説明した方法により析出した希土類不純物は、めっき処理を行う温度以下になっても、再溶解せず、めっき液中の不純物濃度は上がらないことを確認した。

0 hr is an analysis value of the plating solution collected at 90 ° C. It was confirmed that the rare earth impurities deposited by the method described above did not re-dissolve even when the temperature was lower than the temperature at which the plating treatment was performed, and the impurity concentration in the plating solution did not increase.

Based on the above experimental example, a desirable heating temperature will be described.
From the result of Experimental Example 2, when the heating state is maintained at 60 ° C. or higher, the amount of Nd impurities is reduced in the plating solution after filtration, and the reduction effect increases as the heating temperature increases. It was.
The relationship between the amount of Nd impurities and the occurrence of double plating or peeling of the plating film varies depending on the plating conditions. However, when the amount of Nd impurities is about 200 ppm, they are not observed.
When Nd impurities are removed for one week (168 hours), the heating temperature is reduced to about 200 ppm at 60 ° C. Similarly, it is confirmed that almost the same effect can be obtained in 5 days (120 hours) at 70 ° C, 3 days (72 hours) at 80 ° C, and 24 hours (1 day) at 90 ° C and 95 ° C. .
Thus, the time required for reducing the impurities varies depending on the heating temperature of the plating solution.
When one week is set as a production unit period, the plating solution which is held at 60 ° C. for 168 hours and then filtered can be sufficiently used for the plating treatment, and at 70 ° C., the amount of impurities which can be plated can be reduced to 5 days. Similarly, at 80 ° C., 90 ° C., and 95 ° C., impurities in the plating solution can be reduced in a shorter time.

In consideration of Experimental Example 4 in which the heating time was 24 hours or less, when heating was performed at 90 ° C., the precipitation of impurities had already begun when about 3 hours passed, and the amount of impurities decreased by about 10%. ing. It can be seen that impurities can be removed by filtration of the precipitate.
From this, the precipitation of rare earth impurities is expected to start in a short time as the heating temperature increases. Therefore, the rare earth impurities are precipitated by heating the plating solution containing rare earth impurities to an appropriate temperature with a heat exchanger for heating, etc., and then cooling and filtering to efficiently remove the rare earth impurities from the plating solution. Can be removed. Considering the results of Experimental Example 2, the amount of impurities decreased by about 35% in 24 hours at 80 ° C heating, and if 80 ° C or higher is selected as the heating temperature, impurities can be precipitated in a short time. Thus, it was confirmed that more efficient impurity removal was possible.
In addition, from the results of Experimental Example 5, the precipitate once deposited does not re-dissolve in the plating solution even if the temperature of the plating solution is lowered below the plating treatment temperature. Cooling to the temperature before heating (the temperature at which the plating treatment is performed) and then filtering makes it unnecessary to adjust the temperature when returning the filtered plating solution to the plating tank. Therefore, it is possible to continuously remove impurities in a plating solution without stopping the plating process, and to provide a plating process capable of forming a plating film having a stable and efficient property in industrial scale production. Can do.

In the above experimental examples, the effect of reducing Nd, Pr and Dy impurities was confirmed, but Tb and other rare earth impurities can also be reduced.
Furthermore, Fe impurities and Cu impurities in the plating solution can also be reduced.

Based on the above experimental example, a plating tank, heating means, cooling means, separation / removal means, and moving means were selected, and the apparatus of the present invention was manufactured.
Each means constituting the removing apparatus of the present invention desirably has heat resistance and at least a portion that directly touches the plating solution has acid resistance (or alkali resistance).
An embodiment of the removal apparatus of the present invention will be described based on the configuration shown in FIG. In addition, the specific functions and operations of each means including the plating tank are as described above, and will be omitted below.
Plating tank: 4 in the figure is a plating tank for carrying out an electric nickel plating solution, and the material is PVC (vinyl chloride). A Watt bath was used as the plating solution. The plating temperature was 50 ° C.
Heating means: 7 in the figure is a heating means, and a heat exchanger was used. As a heat source, steam generated by a boiler (not shown) was used, and the material (part in contact with the liquid) through which the plating solution passes was titanium.
When removing the rare earth impurities, the plating solution was heated to 90 ° C. by this heating means and held for a certain period of time.
Cooling means: 8 in the figure is a cooling means, and a heat exchanger was used. A known refrigerant was cooled in a refrigerator and the electric nickel plating solution heated in the heating heat exchanger was cooled to 50 ° C. The material through which the plating solution passes (wetted part) was titanium.
Separation and removal means: 9 in the figure is a separation and removal means, and a known filter using a pincushion filter was used.
Moving means: 6 in the figure is a pump for moving the plating solution from the plating tank 4, and a resin pump was used at least in contact with the plating solution in consideration of acid resistance.
Connecting means: The piping connecting the above-mentioned means 7, 8 and 9 and the piping connecting the separating / removing means 9 and the plating tank 4 were made of heat-resistant PVC.
In the figure, reference numerals 5 and 10 denote valves, and the flow rate of the plating solution moved (liquid fed) to each of the means 7, 8, 9 and the plating tank 4 was adjusted.

When the rare earth impurities were removed while performing electro nickel plating on the surface of the R—Fe—B based sintered magnet under the same conditions as in Experimental Example 1 using the above apparatus, the same degree as in Experimental Example 1 was obtained. It was confirmed that the removal of rare earth impurities can be realized and the increase of rare earth impurities in the plating solution during the plating process can be substantially suppressed.

  The present invention dissolves in a plating solution when plating a rare earth magnet, and can efficiently remove rare earth impurities in the electronickel plating solution that cause so-called plating defects, and has industrial applicability.

DESCRIPTION OF SYMBOLS 1,9 Filter 2,6 Pump 3,5,10 Valve 7 Heating exchanger for heating 8 Heat exchanger for cooling 20 Plating solution filtration system 30 Plating solution impurity removal system

Claims (7)

An apparatus for removing rare earth impurities in an electronickel plating solution, comprising: a heating means for heating an electronickel plating solution containing rare earth impurities; and an electronickel plating solution containing precipitates precipitated by heating by the heating means. A removing device comprising cooling means for cooling and separation / removal means for separating and removing the precipitate from the electro nickel plating solution cooled by the cooling means.   The heating means can heat the electronickel plating solution containing the rare earth impurities to 80 ° C. or more, and the cooling means contains the precipitate heated by the heating means. The removing device according to claim 1, wherein the removing device can be cooled to a temperature before heating.   The removal apparatus according to claim 1 or 2, wherein the heating means is a heating heater or a heating heat exchanger, and the cooling means is a cooling pipe or a cooling heat exchanger.   The removal apparatus according to any one of claims 1 to 3, wherein the separation and removal means is a filter or a sedimentation tank.   The heating means, the cooling means, and the separation / removal means are connected to a liquid storage tank for storing an electronickel plating solution containing a rare earth impurity through the heating means. The removal apparatus of crab.   The said liquid storage tank is a plating tank, It is connected so that the electric nickel plating liquid from which the said deposit was removed by the said separation removal means can be returned to the said plating tank. Removal device. 7. A pump is disposed between the plating tank and the heating means as a moving means for moving the electric nickel plating solution containing rare earth impurities stored in the plating tank to the heating means. The removal device described.

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