JPH0121209B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for extracting metal ions by mixing and contacting an organic solvent containing metal ions with a fluoride stripping solution.
The present invention relates to an improvement in an apparatus for back-extracting (stripping) metal ions, precipitating them as metal fluoride or metal fluoride complex crystals, and separating a stripping solution after back-extraction from an organic solvent.

In the solvent extraction method, a fluoride stripping solution (HF, NH ₄ HF ₂ ,
aqueous solution containing one or more types of NH ₄ F)
As an apparatus for back-extracting metal ions and precipitating them as fluoride or metal fluoride complex crystals, an inverted cone-shaped crystallization apparatus disclosed in JP-A-58-81402 has been disclosed. ing. When back-extracting metals using this crystallizer on an industrial scale, there may be problems such as adhesion of precipitated crystals to the vessel walls, deposition at the bottom of the device, solidification, or incorporation of organic solvent into the crystal slurry. Phenomena that interfered with operation occurred, and in order to solve these problems, an improved invention was invented for the "Metal Stripping Material Analysis Apparatus" filed on March 30, 1959.

However, even with the above-mentioned improvements, the problem of precipitated crystalline particles getting mixed into the organic solvent, adhering to and depositing in the overflow weir connected to the organic solvent standing area, and clogging the weir has not been solved, and the present application is The problem was solved by improving the organic solvent stripping solution mixing tank and stripping solution cooling zone.

An object of the present invention is to provide a metal back extraction device which overcomes the drawbacks caused by the mixing tank of conventional devices and which is configured to prevent crystals from adhering to the vessel wall and facilitates continuous operation of the device. be.

That is, the present invention has a crystal growth zone or a stripping solution cooling zone and a crystal separation zone below a mixing tank containing an organic solvent containing a metal ion and a fluoride stripping solution, and the crystals extract metal ions. The organic solvent contained in the organic solvent and the heated fluoride-based stripping solution are brought into mixed contact with each other in the mixing tank to back-extract metal ions as fluoride or metal fluoride complex, thereby crystallizing the fluoride or metal fluoride complex. In the inverted conical crystallizer configured to grow the crystal in the crystal growth zone or the stripping liquid cooling zone and to separate the crystal in the crystal separation zone, an organic solvent supply port is provided in the downcomer pipe disposed in the mixing tank. There is provided a metal back-extraction device, characterized in that it is provided at a position below the stripping liquid supply port and above the lower end of the downcomer pipe, thereby preventing crystals from adhering to the vessel wall.

The present invention also has a crystal growth zone or a stripping solution cooling zone and a crystal separation zone below a mixing tank of an organic solvent containing an extracted metal ion and a fluoride stripping solution, and the crystals contain a crystal that extracts and contains metal ions. The organic solvent and the heated fluoride stripping solution are brought into mixed contact with each other in the mixing tank to back-extract metal ions as fluoride or metal fluoride complex, and the crystals of the fluoride or metal fluoride complex are grown in a crystal growth zone or a stripper cooling zone;
In an inverted conical crystallizer configured to separate crystals in a crystal separation zone, an organic solvent supply port is arranged in a downcomer pipe disposed in the mixing tank at a lower end of the downcomer pipe below a stripping solution supply port. A cooling zone is provided in the lower part of the inverted conical device body and connected to an external heat exchanger. and a forced circulation zone having at least one blowing nozzle oriented substantially tangentially so as to prevent crystals from adhering to the vessel wall. It is something.

The details of the present invention will be explained in detail based on the drawings, but the present invention is not limited thereto. While FIG. 1 shows an example of a conventional device, FIGS. 2 and 3 show examples of the metal back-extraction device of the present invention.

The organic solvent 2 containing extracted metal ions is introduced through a supply port 3 and the heated fluoride stripping solution 4 is introduced through a supply port 5 into a mixing tank or a mixing zone 6, where they are mixed by a stirring device 7. The metal ions in the organic phase are extracted back into the aqueous phase as fluoride or metal ammonium fluoride salts. The stripping solution 4, whose specific gravity has increased due to the stripping of metal ions, descends in the downcomer 11 while separating the organic solvent and precipitating crystals of fluoride or metal ammonium fluoride salt having relatively low solubility. The lower end of the downcomer pipe 11 is connected to the crystal growth zone 12 in the apparatus shown in FIGS. 1 and 2, and to the stripping liquid cooling zone 1 in the apparatus shown in FIG.
3, and is designed to promote the separation and rise of the descending stripping solution and the organic solvent that descends accompanying the precipitated crystals.

The organic solvent overflows from the mixing tank or mixing zone 6, is separated into the standing area 8, passes through the overflow weir 9, and is discharged from the organic solvent outlet 10. The stripping solution and crystals that descended through the downcomer pipe 11 enter the crystal growth zone 12.
Alternatively, it is guided to the stripping liquid cooling zone 13. This zone is connected via piping to a heat exchanger 14, and by cooling the stripping liquid heated in the mixing tank 6, the growth of crystals is promoted, and some of the crystals are also classified.

FIG. 3 shows an improved version of the apparatus shown in FIG. 2, in which a forced circulation zone 15 is further provided inside the cooling zone 13, and the temperature and concentration of the stripping solution are controlled while giving fluidity to the crystal slurry. By keeping the composition uniform, care is taken to prevent crystals from adhering to the vessel wall, depositing at the bottom of the device, and solidifying. As shown in FIG. 3b, the forced circulation flow is particularly preferably constructed in such a way that at least one stripping liquid outlet nozzle 19 forces an approximately tangential flow.

After descending through the downcomer pipe 11, the stripping liquid 4 finally ascends through the crystal separation zone 16 and is discharged from the apparatus through the discharge port 17. Further, the crystals are appropriately discharged as a slurry from the crystal discharge pipe 18 and subjected to solid-liquid separation.

The effect of the position of the organic solvent supply port 3 in the mixing tank 6, which is the main improvement of the metal stripping apparatus of the present invention, will be explained. In the conventional device shown in Fig. 1,
Since the organic solvent supply port 3 is located at the upper part of the mixing tank 6 and at almost the same height as the stripping liquid supply port 5, the residence time of the organic solvent in the mixing tank 6 is short, and the generation of crystal particles is prevented. Since this occurs at a relatively upper portion of the organic phase, fine particles of precipitated crystals were easily incorporated into the organic phase. As a result, the problem of crystal fine particles adhering to and depositing on the organic solvent overflow weir 8 occurred several days after the start of operation of the apparatus, resulting in repeated problems of clogging the weir.

On the other hand, in the apparatus of the present invention, the organic solvent supply port 3 is located below the stripping liquid supply port 5 in the mixing tank 6 and the downcomer pipe 11
Therefore, the residence time of the organic solvent in the mixing tank 6 is longer than in the conventional device. In addition, crystal particles are generated at a relatively lower part of the mixing tank 6, and the flow of the organic solvent from the organic solvent supply port is an upward flow, whereas the stripping solution supply port is located at the top of the mixing tank, so that the stripping solution and crystals The flow is a downward flow, and the organic solvent, stripping solution, and crystals come into countercurrent contact within the mixing tank 6. As a result, the crystalline particles that rise with the organic solvent are removed as the organic solvent rises, and the number of crystalline particles that are finally incorporated into the organic phase is significantly reduced. It is possible to prevent adhesion and buildup on the surface of the 8, and blockage of the weir.

As explained above, the object of the present invention can be achieved if the organic solvent supply port 3 is provided below the stripping liquid supply port 5 in the mixing tank 6 and above the lower end of the downcomer pipe 11. However, this effect is most noticeable in a device in which the organic solvent supply port 3 is provided immediately above the lower end of the downcomer pipe 11. Furthermore, in the apparatus of the present invention shown in FIG. 3, which has a forced circulation zone 15 inside the stripping liquid cooling zone 13 as the lower structure of the apparatus, the organic solvent is taken into the formed crystals and the crystals are removed. Adhesion to the vessel wall can be more effectively prevented, and long-term continuous operation of the apparatus becomes easier.

Furthermore, variations in the shape of the organic solvent supply port 3 are also within the scope of the present invention. Although the purpose of the present invention can be achieved even if the organic solvent supply port 3 has a single nozzle shape, it is necessary to increase the contact efficiency between the organic solvent rising from the supply port 3 and the stripping liquid, etc. descending. This can be achieved even more effectively if the effective area of the supply port opening is increased. Examples of this embodiment are shown in FIGS. 4 and 5, but the shape of the supply port 3 is not limited thereto.

As explained in detail above, by improving the conventional device by installing the organic solvent supply port below the stripping solution supply port in the mixing tank and above the bottom end of the downcomer pipe, it is possible to prevent organic solvent overflow. Trouble such as clogging can be prevented and continuous operation of the device can be easily carried out.

〔Example〕

30v/v%D2EHPA [di-(2-ethylhexyl)]
Using an organic solvent consisting of phosphoric acid] and 70v/v% n-paraffin, an organic solvent containing 16.3 to 18.4g/extracted Fe ³⁺ ions at a temperature of 21 to 23°C was extracted in an amount of 2 m ³ /
was introduced into the mixing tank 5 of the apparatus of the invention shown in FIG. In this mixing tank 5, the organic solvent supply port 3 was located directly above the lower end of the downcomer pipe 11, and the stripping solution supply port 5 was located 185 cm above the organic solvent supply port 3. 118-130g/NH ₄ HF ₂ as a stripper,
3.5 HF at 4-9g/at a temperature of 45-47℃
Continuous operation was carried out while supplying the mixture to the mixing tank 5 at a rate of m ³ /hour. As a result, even after 30 days had passed since the start of operation, almost no crystals were attached to the organic solvent overflow weir 8, and there was no problem in continuous operation of the apparatus.

[Brief explanation of drawings]

FIG. 1 is a diagrammatic sectional view of an example of a conventional device, FIGS. 2 and 3a are diagrammatic sectional views of a metal back-extraction device of the present invention, and FIG. 3b is a diagrammatic sectional view taken along the X-Y line of FIG. 3a. 4 and 5 are diagrammatic perspective views showing examples of the shape of the organic solvent supply port 3. Explanation of symbols 1...Metal back extraction device main body, 2...Metal extraction organic solvent, 3...Organic solvent supply port, 4...Removal liquid (aqueous phase), 5...Removal liquid supply port, 6...Mixing tank, 7
... Stirring device, 8... Organic solvent standing area, 9... Organic solvent overflow weir, 10... Organic solvent outlet, 11... Downcomer, 12... Crystal growth zone, 13... Stripper cooling zone, 14... Heat exchanger , 15... Stripping liquid forced circulation zone, 16... Crystal separation zone, 17... Stripping liquid outlet, 18... Crystal discharge pipe, 19... Stripping liquid blowing nozzle.

Claims (1)

[Claims] 1. A crystal growth zone or a stripping solution cooling zone and a crystal separation zone are provided below a mixing tank of an organic solvent containing an extracted metal ion and a fluoride stripping solution, and a crystal growth zone or a stripping solution cooling zone and a crystal separation zone are provided. The organic solvent containing the extraction and the heated fluoride-based stripping solution are brought into mixed contact with each other in the mixing tank to back-extract metal ions as fluoride or metal fluoride complex, thereby forming crystals of the fluoride or metal fluoride complex. In the inverted conical crystallizer configured to grow crystals in the crystal growth zone or stripping liquid cooling zone and separate the crystals in the crystal separation zone, an organic solvent supply port is provided in the downcomer pipe disposed in the mixing tank. A metal back-extraction device, characterized in that a metal back-extraction device is provided at a position below the stripping liquid supply port and above the lower end of the downcomer pipe, thereby preventing crystals from adhering to the vessel wall. 2. A crystal growth zone or a stripping solution cooling zone and a crystal separation zone are provided below the mixing tank of an organic solvent that extracts and contains metal ions and a fluoride stripping solution, and the crystals are mixed with an organic solvent that extracts and contains metal ions. A heated fluoride-based stripping solution is mixed and contacted in the mixing tank to back-extract metal ions as fluoride or metal fluoride complex, and crystals of the fluoride or metal fluoride complex are transferred to the crystal growth zone or the metal fluoride complex. In an inverted conical crystallizer configured to grow crystals in a stripping liquid cooling zone and separating crystals in a crystal separation zone, an organic solvent supply port is connected to a stripping liquid supply port in a downcomer pipe disposed in the mixing tank. A cooling zone is provided at the lower part of the downcomer pipe above the lower end of the downcomer pipe, and is provided at the bottom of the inverted conical device body and is connected to an external heat exchanger. A forced circulation zone having at least one blowing nozzle oriented in a substantially tangential direction so as to cause a swirling flow in the stripping liquid at the lower part, thereby preventing crystals from adhering to the vessel wall. Metal reverse extraction equipment.