KR101746586B1 - Method For Recovering Rare Earth By Bio-Adsorption Form Permanent Magnets - Google Patents

Abstract

The present invention relates to a method of recovering rare earths from a permanent magnet using bioadsorption. By using a bioabsorbent manufactured using a microalgae extract, a rare earth metal is easily recovered, thereby simplifying the process and reducing manufacturing costs. To a rare earth recovery method.
SUMMARY OF THE INVENTION The present invention, which was conceived to solve the problems of the conventional art described above, includes a dissolving step in which a permanent magnet is dissolved by nitric acid; A precipitate removing step of adjusting the pH of the dissolving solution in which the permanent magnet is dissolved to remove the precipitate; An addition step of adding fine algae particles to the dissolution liquid from which the precipitate has been removed; Agitation and adsorption in which neodymium and dysprosium are adsorbed on the microalgae particles by stirring the solution to which the fine algae particles are added; And a recovery step of recovering the adsorbed neodymium and dysprosium. The present invention also provides a rare earth recovery method for a permanent magnet using bioabsorption.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering rare earths from a permanent magnet using bio-

The present invention relates to a method of recovering rare earths from a permanent magnet using bioadsorption. By using a bioabsorbent manufactured using a microalgae extract, a rare earth metal is easily recovered, thereby simplifying the process and reducing manufacturing costs. To a rare earth recovery method.

Rare earths (rare earths) means rare earths, and rare earth metals means metals with a total content of less than 300 ppm in the crust. In general, it is a name that bundles 17 elements including atomic numbers 57 to 71, including lanthanum, and scandium and yttrium. The above-mentioned elements of nitrogen are grouped together as rare earths because they have similar chemical properties and exist in groups in the minerals.

Rare earth consumption is very small compared to petroleum and other mineral resources, but not qualitatively. Rare earths are chemically stable and have inherent properties to transfer heat well, but they are difficult to separate because they are similar in chemical and physical properties. In addition, most of the radioactive materials are mixed, which is not easy to collect. Rare earths, which are becoming increasingly widespread, are regarded as an essential resource for high-tech products such as mobile phones, semiconductors, and hybrid cars.

The prior art for obtaining the rare earth metal is a technique of extracting a rare earth metal from a pulsed permanent magnet and dissolving the pulsed permanent magnet in a strongly acidic solution and selectively precipitating a specific rare earth metal through pH control. This complex and significant amount of strongly acidic or basic solution has to be used, resulting in poor final yield and purity.

Another prior art is a method of recovering rare earth metals by dissolving permanent magnets in a melt of a specific inorganic salt. However, the process must be carried out at a high temperature and, in order to remove Fe (iron) and B (boron) It has a problem that not only the wet method but also the separation and purification process of Nd (neodymium) and Dy (dysprosium) should proceed more.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rare earth recovery method capable of simplifying a process and designing a process capable of reducing energy.

It is also an object of the present invention to provide a rare earth recovery method for minimizing the chemical solution to be used in further achievement by simplifying the rare earth recovery process, thereby preventing environmental pollution.

The technical objects to be achieved by the present invention are not limited to the technical matters mentioned above, and other technical subjects which are not mentioned can be clearly understood by those skilled in the art from the description of the present invention .

SUMMARY OF THE INVENTION The present invention, which was conceived to solve the problems of the conventional art described above, includes a dissolving step in which a permanent magnet is dissolved by nitric acid; A precipitate removing step of adjusting the pH of the dissolving solution in which the permanent magnet is dissolved to remove the precipitate; An addition step of adding fine algae particles to the dissolution liquid from which the precipitate has been removed; Agitation and adsorption in which neodymium and dysprosium are adsorbed on the microalgae particles by stirring the solution to which the fine algae particles are added; And a recovery step of recovering the adsorbed neodymium and dysprosium. The present invention also provides a rare earth recovery method for a permanent magnet using bioabsorption.

In the present invention, the amount of nitric acid used in the dissolution step is preferably 2.5 to 3.5 M.

In the present invention, the dissolving step is conducted for 2.5 to 3.5 hours, and the temperature is preferably 65 to 75 ° C.

In the present invention, it is preferable that the ratio of the weight of the permanent magnet to the volume of the nitric acid solution is 1:20 to 1:30.

In the present invention, sodium hydroxide is preferably used to adjust the pH of the precipitate removing step.

In the present invention, it is preferable that the pH of the precipitate removing step is adjusted to 2.5 to 3.5.

In the present invention, the fine algae particles in the adding step are preferably in the form of microparticles.

In the present invention, the microparticulate microparticulate particles are preferably made of Spirulina extract.

In the present invention, it is preferable that the stirring and the adsorption step are carried out by stirring and adsorbing at 160 to 200 rpm for 22 to 26 hours.

According to the rare earth recovery method of the permanent magnet using bio-adsorption of the present invention, there is an effect of providing a rare earth recovery method capable of simplifying the process and designing a process capable of reducing energy.

In addition, according to the rare earth recovery method in the permanent magnet using bio-adsorption of the present invention, there is an effect of providing a rare earth recovery method for minimizing the chemical solution to be used for further public works by simplifying the step of recovering rare earths, thereby preventing environmental pollution.

1 is a flowchart of a rare earth recovery method in a permanent magnet using bio-adsorption according to an embodiment of the present invention.
FIG. 2 is a photographic view of a precipitate generated when the dissolution step according to an embodiment of the present invention is a 3M nitric acid, 3 hours, 70 ° C, and a permanent magnet mass: nitrate volume ratio of 1:25.
FIG. 3 is a photograph of a precipitate generated when the dissolution step according to an embodiment of the present invention is performed under conditions of 3M hydrochloric acid, 3 hours, 70 ° C, and a permanent magnet mass: hydrochloric acid volume ratio of 1:25.
4 is a photographic view of a precipitate generated when the dissolution step according to an embodiment of the present invention is 3M sulfuric acid, 3 hours, 70 ° C, and a permanent magnet mass: sulfuric acid volume ratio of 1:25.
FIG. 5 is a photograph immediately after dissolution when 3M nitric acid is used at a ratio of permanent magnet mass: nitric acid volume of 1:25 in the dissolution step according to an embodiment of the present invention. FIG.
FIG. 6 is a photograph of a case where 3M nitric acid is used at a ratio of a permanent magnet mass: nitric acid volume of 1:25 in a dissolution step according to an embodiment of the present invention after one week has passed after dissolution.
7 is a photograph immediately after dissolution when 3M hydrochloric acid is used at a ratio of permanent magnet mass: hydrochloric acid volume of 1:25 in the dissolution step according to an embodiment of the present invention.
FIG. 8 is a photograph of a case where 3M hydrochloric acid is used at a ratio of a permanent magnet mass: hydrochloric acid volume ratio of 1:25 in a dissolution step according to an embodiment of the present invention and one week after dissolution. FIG.
Fig. 9 is a photograph of a dissolution liquid obtained by dissolving 1 g of a permanent magnet in 50 ml of 3 M nitric acid. Fig.
10 is a photograph showing a dissolution liquid obtained by dissolving 2 g of the permanent magnet in 50 ml of 3 M nitric acid according to an embodiment of the present invention.
11 is a graph showing the concentrations of Fe, Nd, Dy, and B contained in a dissolution solution obtained by dissolving 1 g of a permanent magnet and 2 g of a permanent magnet in 50 ml of 3 M nitric acid.
12 is a graph showing the ion concentrations of Fe, Nd, Dy and B according to the pH of the dissolving solution in which the permanent magnet is dissolved.
13 is a graph showing percentages of removal of Fe, Nd, Dy, and B according to the pH of a dissolving solution in which a permanent magnet is dissolved;
14 is a graph showing the adsorbed contents of B, Nd and Dy depending on an adsorbent in a dissolving solution in which a permanent magnet is dissolved;
15 is a graph showing adsorption ratios of B, Nd and Dy depending on an adsorbent in a dissolving solution in which permanent magnets are dissolved;
16 is a graph showing the weight ratios of B, Nd and Dy depending on the adsorbent of the dissolving liquid in which the permanent magnets are dissolved.
17 is an enlarged view of a spirulina microparticle according to an embodiment of the present invention.
18 is a graph showing adsorption amounts of Nd and Dy depending on pH in spirulina microparticles which are adsorbents of a dissolving solution in which permanent magnets are dissolved;
19 is a graph showing the recovery rates of Nd and Dy according to the amount of spirulina microparticles under pH 3 conditions;

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be interpreted in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined. Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

Disclosure of Invention Technical Problem [8] The present invention has been devised to solve the problems of the prior art described above, and provides a rare earth recovery method in a permanent magnet using bio-adsorption. Specifically, FIG. 1 is a flowchart of a rare earth recovery method in a permanent magnet using bio-adsorption according to an embodiment of the present invention. As shown in FIG. 1, the present invention performs a sediment removing step (S103) for removing sediments generated in the dissolution step after a dissolution step (S101) for dissolving the permanent magnet. Thereafter, an addition step (S105) of adding a bioabsorbent to the dissolution liquid from which the precipitate has been removed is carried out. (S107) for adsorbing the rare earth metal adsorbed on the bioabsorbent, and then recovering the rare earth metal adsorbed on the bioabsorbent (S109). The recovering step (S109) Thereby providing a rare earth recovery method.

More specifically, the present invention relates to a method for manufacturing a permanent magnet, comprising: a dissolving step (S101) in which a permanent magnet is dissolved by nitric acid; A precipitate removing step (S103) in which the pH of the dissolution liquid in which the permanent magnet is dissolved is adjusted to remove the precipitate; An addition step (S105) of adding fine algae particles to the dissolution solution from which the precipitate is removed; Stirring and adsorption (S107) in which neodymium and dysprosium are adsorbed on the fine algae particles by stirring the dissolution solution to which the fine algae particles are added; And a recovering step (S109) of recovering the adsorbed neodymium and dysprosium. The present invention also provides a method for recovering rare earths from a permanent magnet using bio-adsorption. In the present invention, the amount of nitric acid used in the dissolution step (S101) is preferably 2.5 to 3.5M, the dissolution step (S101) is performed for 2.5 to 3.5 hours, and the temperature is preferably 65 to 75 ° C. Further, in the dissolution step (S101), the ratio of the weight of the permanent magnet to the volume of the nitric acid solution is preferably 1:20 to 1:30, and the precipitate removing step (S103) desirable. In addition, it is preferable that the pH is adjusted to 2.5 to 3.5 in the step of removing precipitate (S103), and the microalgae particles in the adding step (S105) are preferably microparticulate. In addition, the microparticulate microparticulate particles are preferably prepared from Spirulina extract, and the stirring and adsorption step (S107) is preferably stirred and adsorbed at 160 to 200 rpm for 22 to 26 hours.

According to the present invention, it is possible to minimize the use of the chemical solution required for the rare earth recovery and to prevent staining of the flower, and at the same time, it is possible to reduce the manufacturing cost by simplifying the process by designing the energy saving process.

[Example]

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are merely illustrative of the present invention and that the scope of the present invention is not construed as being limited by these embodiments.

In order to confirm the acidic solution suitable for the present invention, the dissolution step (S101) was carried out by adding 2 g of the permanent magnet using nitric acid, hydrochloric acid and sulfuric acid to the production method of the present invention. FIG. 2 is a photograph of sediments generated when the dissolution step (S101) according to an embodiment of the present invention is performed under conditions of 3M nitric acid, 3 hours, 70 ° C, and permanent magnet mass: nitric acid volume ratio of 1:25. When the bottom of the spherical flask shown in FIG. 2 is confirmed, it can be confirmed that a small amount of precipitate is present. FIG. 3 is a photograph of a precipitate generated when the dissolution step (S101) according to an embodiment of the present invention is performed under conditions of 3M hydrochloric acid, 3 hours, 70 ° C, and permanent magnet mass: hydrochloric acid volume ratio of 1:25, Is a photographic view of a precipitate generated when the dissolution step (S101) according to an embodiment of the present invention is performed under conditions of 3M sulfuric acid, 3 hours, 70 ° C, and a ratio of permanent magnet mass: sulfuric acid volume of 1:25. When the bottom of the flask shown in FIGS. 3 and 4 was confirmed, it can be seen that a larger amount of precipitate was formed than the precipitate shown in FIG. As a result, it can be confirmed that nitric acid was used as a solvent and the precipitate was formed in the smallest amount. In the present invention, the dissolution step (S101) was performed using nitric acid.

On the other hand, in order to confirm whether the use of the nitric acid as an acid solution is appropriate, the color change with time of the dissolution solution subjected to the dissolution step (S101) was observed. FIG. 5 is a photograph immediately after dissolution when 3M nitric acid is used at a ratio of a permanent magnet mass: nitric acid volume of 1:25 in the dissolution step (S101) according to an embodiment of the present invention. FIG. FIG. 10 is a photograph of a case where 3M nitric acid is used in a dissolution step (S101) according to the example in which the ratio of permanent magnet mass: nitric acid volume is 1:25, after one week has elapsed. 5 and FIG. 6, it can be seen that no color change was observed immediately after dissolution and after one week after dissolution. On the other hand, FIG. 7 is a photograph of a case where the ratio of permanent magnet mass: hydrochloric acid volume in the dissolution step (S101) according to an embodiment of the present invention is 1: 25 and 3M hydrochloric acid is used, FIG. 3 is a photograph of a case where 3M hydrochloric acid is used at a ratio of the mass of permanent magnet to the volume of hydrochloric acid at a ratio of 1:25 in the dissolution step (S101) according to one embodiment. 7 and 8, it can be seen that the color after the dissolution of the permanent magnet with hydrochloric acid and after the dissolution of the permanent magnet changes significantly to a transparent yellow. It can be confirmed that the metal ions in the solution are oxidized with the elapse of time in the solution which dissolves the permanent magnet with hydrochloric acid which is not nitric acid. Therefore, it is preferable to apply nitric acid, which keeps the metal ions in the dissolving solution dissolved in the permanent magnet so as not to be oxidized even after a lapse of time.

It is also preferable that the ratio of the volume of the 3M nitric acid solution to the mass of the permanent magnet is 1:25. FIG. 9 is a photograph of a dissolution solution obtained by dissolving 1 g of a permanent magnet in 50 ml of 3 M nitric acid. FIG. 10 is a graph showing the dissolution profile of a dissolution solution obtained by dissolving 2 g of a permanent magnet according to an embodiment of the present invention in 50 ml of 3 M nitric acid It is a picture. The concentration of the dissolving solution obtained by dissolving 2 g of the permanent magnet with 50 ml of 3 M nitric acid is higher than that of the dissolving solution obtained by dissolving 1 g of the permanent magnet with 50 ml of 3 M nitric acid. Visual confirmation is possible. 11 is a graph showing the concentrations of Fe, Nd, Dy, and B contained in the dissolution liquid obtained by dissolving 1 g of the permanent magnet and 2 g of the permanent magnet in 50 ml of 3 M nitric acid, respectively. The horizontal axis corresponds to the metal, and the vertical axis corresponds to the metal concentration. The 1 g magnet in FIG. 11 means a dissolution solution obtained by dissolving 1 g of a permanent magnet with 50 ml of 3 M nitric acid, and the 2 g magnet means a dissolution solution obtained by dissolving 2 g of a permanent magnet in 50 ml of 3 M nitric acid. The concentration of the above solution was confirmed by inductively coupled plasma (ICP) emission spectroscopy. As shown in FIG. 11, when the concentration of the solution obtained by dissolving 2 g of the permanent magnet in 50 ml of 3 M nitric acid in comparison with the solution obtained by dissolving 1 g of the permanent magnet of Fe, Nd, Dy and B in 50 ml of 3 M nitric acid It can be confirmed that the concentration is about twice or more.

On the other hand, in the precipitate removing step (S 103) of the present invention, sodium hydroxide (NaOH) is preferably used to adjust the pH, and the pH is preferably adjusted to 2.5 to 3.5. After dissolving the permanent magnet in 3M nitric acid, the pH was adjusted with sodium hydroxide to remove dissolved iron ions, and precipitates were formed as the pH increased. Then, the concentrations of Fe, Nd, Dy and B ions were confirmed by ICP emission spectrometry, in which precipitates were removed by centrifugation. FIG. 12 is a graph showing the ion concentrations of Fe, Nd, Dy and B according to the pH of the dissolving solution in which the permanent magnets are dissolved, FIG. 13 is a graph showing the concentrations of Fe, Nd, Dy and B according to the pH of the dissolving solution B < / RTI > 12, the horizontal axis represents the pH of the solution, and the vertical axis represents the concentration of the metal. 13, the horizontal axis represents the pH of the solution, and the vertical axis represents the removal percentage of each metal. As shown in FIG. 12, it can be seen that the ion concentration of Fe drastically decreases in comparison with the ion concentrations of Nd, Dy and B near pH 3. That is, iron ions were rapidly removed at around pH 3, and the amounts of Nd and Dy dissolved were not significantly different.

In order to select an adsorbent for the adsorption of Nd and Dy according to the present invention, various sorbents in the form of microparticles such as silk sericin, microalgae extract (spirulina extract), orange peel , Chitosan, alginate, sericin and a mixture of graphene oxide were added to confirm the adsorption performance of rare earth ions. FIG. 14 is a graph showing adsorbed contents of B, Nd and Dy depending on an adsorbent in a dissolving solution in which permanent magnets are dissolved. FIG. In FIG. 14, the abscissa indicates the kind of the adsorbent, and the ordinate indicates the adsorption amount (mg) of rare earth ions per adsorbent (g). As shown in FIG. 14, the adsorption amount of Nd was higher than that of Dy, and adsorption performance of Nd and Dy was excellent in the adsorbent prepared from silk sericin and microalgae extract (Spirulina extract) In particular, it can be confirmed that the adsorbent of microalgae extract (Spirulina extract) adsorbs the most amount of Nd. 15 is a graph showing the adsorption ratios of B, Nd and Dy depending on the adsorbent in the dissolving solution in which the permanent magnets are dissolved. 15, the abscissa represents the adsorbent, and the ordinate represents the adsorption rate. As shown in FIG. 15, it can be confirmed that the microalgae extract (Spirulina extract) exhibits an adsorption ratio of 23% for Nd and 26% for Dy. As a result, it is preferable that the adsorbent is a microalgae extract (spirulina extract) for adsorption of Nd and Dy in the present invention.

16 is a graph showing the weight ratios of B, Nd and Dy according to the adsorbent of the dissolving solution in which the permanent magnets are dissolved. Specifically, FIG. 16 shows the weight ratio of B, Nd and Dy adsorbed by analyzing the adsorbent surface through EDS (Energy Dispersive Spectrometry) after adsorbing rare earth ions. 14 and 15, it was confirmed by ICP emission spectrometry that a large amount of rare earth ions was distributed on the surface of the microalgae extract (spirulina extract) adsorbent having an excellent adsorption ability of rare earth ions, and the microalgae extract (spirulina (18%) and Dy (7%) on the surface of the adsorbent. As a result, the results of the ICP emission spectroscopic analysis of FIG. 16, FIG. 14, and FIG. 15, as well as the rare earth adsorption performance of the microalgae extract (Spirulina extract) adsorbent, are confirmed.

In addition, the microalgae extract is preferably a spirulina extract, and the microalgae is preferably in the form of microparticles. The Spirulina extract is prepared by the following procedure.

1. Powder-type solid Spirulina platensis, the material of the Spirulina extract, was purchased from a US company, Cyan Tech.

2. Spirulina platensis powdered and stored at 4 ℃ until use.

3. Add 20 g of spirulina powder into 1 L of distilled water and stir at 4 ° C for 24 hours to form a mixture.

4. The mixture is then stirred at 5,000 rpm for 10 minutes at 4 < 0 > C.

5. After stirring, filter the supernatant for removal of undissolved fractions.

6. The filtered extract is freeze-dried and stored at 4 ° C until use.

Further, FIG. 17 is an enlarged photograph showing spirulina microparticles according to an embodiment of the present invention. The spirulina microparticles as the adsorbent of the present invention drop the spirulina extract into a methanol solution containing glutaraldehyde (2%, w / v) without any further dissolution process and stir it at 250 rpm for 1 hour. Thereafter, the coagulated spirulina microparticles are recovered by centrifugation (5000 rpm, 30 min).

In addition, in order to find the optimum adsorption pH in the stirring and adsorption step (S107) of the present invention, an experiment was conducted in which the pH of the dissolution solution was readjusted to 1 or 2 to select an optimal adsorption pH. 18 is a graph showing adsorption amounts of Nd and Dy according to pH in spirulina microparticles which are adsorbents of a dissolution solution in which permanent magnets are dissolved. The abscissa of FIG. 18 represents the pH and the ordinate represents the adsorption amount of the metal. As shown in FIG. 18, it can be seen that the adsorption amount is larger when the pH is 3 than when the Nd and Dy are at the pH 1 to 2.

Further, the following experiment was conducted to find the dose of the adsorbent having a recovery of 95% at pH 3. In the experiment, a permanent magnet was dissolved in 3M nitric acid, and iron was removed by adjusting the pH using sodium hydroxide (NaOH). In the above experiment, 0.025 g to 4 g of the adsorbent of spirulina microparticles was charged based on 20 ml of the dissolving solution of the permanent magnet, and the adsorption amount of Nd and Dy was shown by ICP emission spectrometry in FIG. 19 is a graph showing recovery rates of Nd and Dy according to the amount of spirulina microparticles under pH 3 conditions. The horizontal axis in FIG. 19 represents the amount of spirulina microparticles, and the horizontal axis represents the recovery rate. As shown in FIG. 19, it can be seen that the recovery rate of Nd and Dy increases when the amount of the spirulina microparticles as the adsorbent increases. As a result, it was confirmed that the recovery rate of Nd and Dy exceeded 97% when Spirulina microparticles of 2 g or more were loaded.

The present invention can design a process that can reduce energy by simplifying a process by using bio-adsorption, that is, spirulina microparticles as an adsorbent, and it is advantageous to minimize environmental pollution by minimizing a chemical solution to be used in further public works.

Although the present invention has been described in connection with the specific embodiments of the present invention, it is to be understood that the present invention is not limited thereto. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. Various modifications and variations are possible.

S101: Dissolution step
S103: Sediment removal step
S105: Addition step
S107: stirring and adsorption step
S109: Recovery step

Claims (9)

A dissolving step in which the permanent magnet is dissolved by nitric acid;
A precipitate removing step of removing the precipitate by adjusting the pH of the dissolving solution in which the permanent magnet is dissolved to 2.5 to 3.5;
An addition step of adding microparticulate microparticles to the dissolution liquid from which the precipitate has been removed; And
Agitation and adsorption in which neodymium and dysprosium are adsorbed on the microalgae particles by stirring the solution to which the fine algae particles are added; And
And a recovery step of recovering the adsorbed neodymium and dysprosium,
The microparticulate microparticulate particles are made of Spirulina extract,
The method for producing the spirulina extract comprises:
Forming a mixture in which solid spirulina platensis in powder form is added to distilled water to form a mixture;
Stirring the mixture;
Filtering the supernatant of the stirred mixture to produce an extract; And
And a freeze-drying step of freeze-drying the extract through the filtering step.
The method according to claim 1,
Wherein the nitric acid used in the dissolving step is 2.5 to 3.5 M. < RTI ID = 0.0 > 11. < / RTI >
The method according to claim 1,
Wherein the dissolving step is carried out for 2.5 to 3.5 hours, and the temperature is 65 to 75 ° C. The method for recovering rare earths from permanent magnets using bioadsorption.
The method according to claim 1,
Wherein the dissolving step is performed in the ratio of the weight of the permanent magnet to the volume of the nitric acid solution in the range of 1:20 to 1:30.
The method according to claim 1,
Wherein the precipitate removing step comprises adjusting the pH by using sodium hydroxide.
delete delete delete The method according to claim 1,
Wherein the stirring and adsorption step is carried out by stirring and adsorbing at 160 to 200 rpm for 22 to 26 hours.

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