JPH03271117A - Spherical rare earth of oxalate and production thereof - Google Patents

Abstract

PURPOSE:To improve fluidity by maintaining <= a specific temperature and collecting rare earth of oxalate of reaction product of rare earth element ion and oxalate ion. CONSTITUTION:An aqueous solution of one or more of chloride, nitrate, sulfate, etc., of rare earth element such as Y and lanthanide with atomic number 57-71 having >=0.05mol/l concentration is prepared. The temperature of the solution is maintained at >= the freezing point of the aqueous solution and <=20 deg.C and reacted with 1.5-3.0mol based on 1mol of total amount of the rare earth of an aqueous solution of oxalic acid or oxalate while stirring for 1-120 minutes. After the reaction is over, particles of rare earth of oxalate are filtered and separated from the mother liquor while maintaining the solution at <=20 deg.C, washed, then dehydrated by using a dehydrating solvent and dried to give particles of nonagglmomerative spherical crystalline rare earth of oxalate having <=200mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to spherical rare earth oxalate. For more information,
The present invention relates to a highly pure, fine, non-agglomerated, spherical crystalline rare earth oxalate and a method for producing the same.

[Prior Art] Rare earth oxalate is often used as electronic materials and ceramic materials, either in the form of rare earth compounds such as oxides, sulfides, or halides, or in its original form. For such uses, 1. It must be highly pure.

2. It has a large bulk density and a large amount of filling per volume.

3. Good fluidity and easy filling and reaction operations are required.

Conventionally, rare earth oxalate has been produced by the reaction between rare earth ions and oxalate ions, but the resulting rare earth oxalate has an irregular shape, a low bulk density, irregular particle sizes, and a wide particle size distribution. . Therefore, in order to make the particle size uniform, operations such as classification and, in some cases, classification of the pulverized liquid, are required, which is not only complicated, but also causes the inconvenience of contamination with impurities from the equipment.

Japanese Patent Publication No. 57-47133 discloses a method in which yttrium oxalate produced by a reaction between yttrium ions and oxalate ions is held at a temperature of 90 to 100°C in the presence of water and then dried. Yttrium oxalate obtained also by this method has a shape close to a cube. Moreover, if the process is held for a long enough time to ensure its effectiveness, the particle size distribution will remain wide and shift to a method with larger particle sizes, so pulverization and classification will be necessary to obtain fine yttrium oxalate.

[Purpose of the Invention] As a result of extensive research to meet the above requirements, the present inventors have found that when the reaction between rare earth ions and oxalate ions is carried out under specific conditions, non-agglomerated spherical oxalate deposits can be obtained. The present invention was completed by learning that it is possible to do this.

That is, the purpose of the present invention is to provide a spherical oxalic acid deposit that has great industrial value. , and a method of reacting rare earth ions and oxalate ions, characterized in that the temperature is maintained at 20°C or less from the start of the reaction until the obtained rare earth oxalate particles are obtained. It is the law.

[Structure of the Invention J In the present invention, rare earths refer to yttrium and lanthanoids having an atomic number of 57 to 71.

Non-agglomerated means that the individual particles exist independently and are substantially free of agglomerated portions.

In the present invention, spherical means a true sphere and a substantially spherical particle having a ratio of the major axis to the minor axis of 1.5 or less. It is desirable that all particles of oxalic acid deposited in the present invention be spherical, but it is difficult to strictly produce only spherical particles in industrial production, and it is limited to particles in which all particles are spherical. However, it is permissible for rare earth oxalate particles of different shapes to coexist within a range that does not impair fluidity and bulk density.

The average particle size is expressed on a volume basis (Dso), 200
A size smaller than μm can be easily produced. For industrial use, it is usually 1 to 1100p, especially 5 to 501. Im grade is preferred. If the average particle size is too small, it will be difficult to handle and the fluidity will be poor. On the other hand, if it is too large, it will be difficult to manufacture it industrially.

The spherical oxalic acid deposits of the present invention have extremely good fluidity due to their particle size and shape, and the angle of repose measured by the inclination method is 50 degrees or less, which is smaller than the 50 to 70 degrees of conventional products. Furthermore, the bulk density is 50% or more greater than that of irregularly shaped oxalic acid deposits.

In order to produce such spherical oxalic acid deposits, for example, rare earth ions and oxalate ions are reacted at a temperature of 20'C or lower, and the temperature is then lowered to 20°C until the produced rare earth oxalate particles are obtained.
A method for obtaining spherical rare earth oxalate particles by keeping the temperature below °C is mentioned.

Rare earth ions usually include aqueous solutions of water-soluble rare earth compounds such as chlorides, nitrates, sulfates, etc. of rare earth elements.
It may be more than one species. The concentration of the rare earth compound is not particularly limited, but if the concentration is too low, the amount of treatment liquid will increase, which is disadvantageous industrially, so it is usually 0.05 mol /
It is preferable to select from the range of e or more, preferably 0.1 to 0.5 mol/zo.

Oxalate ions include oxalic acid or ammonium oxalate,
Examples include aqueous solutions of oxalate salts such as sodium oxalate, potassium oxalate, and the like. The amount of these oxalate ions used is usually
The molar ratio relative to the total amount of rare earths is preferably selected from a range of 1.5 to 3.0. However, the molar ratio is 1.0 or less (0 in some cases)
．． If the particle diameter is selected from the range of 5 or less), particles with a particularly small particle size (about the size of P) can be obtained.

To carry out the reaction, first prepare an aqueous solution of the rare earth compound,
It is preferable to add an aqueous solution of oxalic acid or oxalate to the solution while keeping the temperature of the solution at a temperature above the freezing point of the aqueous solution and below 20°C. The temperature at this time is particularly important, and since a product with good sphericity tends to be obtained at a low temperature, it is preferably within a range of at least the freezing point of the aqueous solution and at most 10°C.

The rate at which oxalic acid or an aqueous solution of oxalate is supplied to an aqueous solution of a rare earth compound affects the particle size of the resulting oxalic acid deposits, so the total addition time is usually 1 to 120 minutes, preferably 2 to 60 minutes. It is best to choose from a range. As the addition time increases, the average particle size of the plug-spherical oxalic acid deposits tends to increase, but if the addition time exceeds 120 minutes, it tends to become difficult to obtain spherical crystals. On the other hand, if the addition time is extremely short, the particles become fine and spherical particles are difficult to form.

The intensity of stirring during the reaction is related to the average particle size and particle size distribution of the oxalic acid deposits produced, and the higher the stirring intensity, the smaller the average particle size and the sharper the particle size distribution.

In this reaction between rare earth ions and oxalate ions, the maximum average particle size of oxalic acid deposits obtained in one operation is limited to 50 m, but if spherical particles with a larger average size are desired. The same reaction may be repeated by adding the already obtained spherical oxalic acid deposits as seed crystals. By doing so,
It is possible to obtain spherical oxalic acid deposits exceeding 200 μm, but as the particle size increases, the rate of breakage of spherical oxalic acid deposits due to collision with stirring blades, etc. increases, so the average size of spherical crystalline oxalic acid deposits The particle size is 200 μm or less, preferably 1
It is preferable to set the value to 1100p.

The formed spherical oxalic acid deposits are separated from the mother liquor, washed, and dehydrated. For separation, filtration, tilting, centrifugation, etc. can be used. Dispersion cleaning using water several times the amount of rare earth oxalate is usually sufficient for cleaning. For dehydration, water adhering to oxalic acid is replaced and removed using an alcohol such as methanol or ethanol or a dehydrating solvent such as acetone.

It is important that the entire operation of separating, washing and dehydrating the spherical oxalic acid deposits be carried out at a temperature below 20°C, preferably from 0 to 10°C. Spherical oxalic acid deposition is unstable in the presence of adhered water, as the crystal form changes when the temperature is high, so it is necessary to maintain the temperature at a low temperature until the adhered water is substantially removed.

Since the dehydrated spherical oxalic acid deposits are stable even at high temperatures, they can be dried or fired as desired.

When using this method, it is possible to obtain non-agglomerated spherical oxalic acid deposits with high purity and large bulk density, and the average particle size and particle size distribution of the spherical oxalic acid deposits can be controlled within a wide range.

[Examples] Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example 1 A yttrium nitrate aqueous solution (PH = 0.5, freezing point -2.5°C) with a concentration of 0.15 mol/e was poured into a glass separator with a capacity of 1.5 e equipped with four baffles and a cooling jacket. The mixture was charged into a bull flask, and the liquid temperature was maintained at o'c under strong stirring (4 paddle blades, 600 r, p, m).

0.4 e of an oxalic acid aqueous solution having a concentration of 0.8 mol/e was fed into the aqueous solution over a period of 15 minutes using a quantitative pump.

Thirty minutes after the end of the oxalic acid supply, the yttrium oxalate slurry was filtered under reduced pressure using a Nutsche filter.

Subsequently, the yttrium oxalate cake was sprinkled and washed with demineralized water 1e previously cooled to 10°C or lower, and then water adhering to the yttrium oxalate cake was removed with methanol (special grade reagent) 1e cooled to 10°C or lower, and then heated to 100°C. Drying was carried out.

When the shape of the obtained powder was observed by SEM, it was found that it was a spherulite that was close to the perfect sphere shown in FIG. 1 and had no agglomeration. The average particle size of yttrium oxalate is 11.5. As shown in Figure 2, the particle size distribution is 8 to 18. It was extremely sharp.

When the angle of repose and bulk density of this yttrium oxalate powder were measured, the angle of repose (inclination method) was 45 degrees.
The bulk density was 1.05 g/cc.

Example 2 A mixed aqueous solution of yttrium nitrate and europium nitrate with a concentration of 0.144 mol/e (pH = 0.4, freezing point -3°C2Eu/Y = 0.026 atomic ratio) Ie
The same procedure as in Example 1 was carried out except that . The shape of the oxalic acid deposits obtained was observed by SEM, and the results are shown in FIG. The particle shape of the oxalic acid epiphyte mixture was spherical, and the average particle size was 16.8 μm.

Example 3゜98% based on the raw material solution yttrium nitrate aqueous solution 1e
The same procedure as in Example 1 was carried out except that 80 m6 of sulfuric acid was added.
Almost spherical yttrium oxalate with an average particle size of 65 μm was obtained. The results are shown in Figure 4.

Comparative Example 1 Yttrium oxalate powder was obtained in the same manner as in Example 1, except that the liquid temperature was kept at room temperature (25°C).

The results of observing the shape of the obtained powder using SEM are shown in the fifth section.
Shown in the figure. This item has an irregular shape that clearly looks like crushed rock, and has sharp edges. powder, and the average particle size was 9.6μ.

The angle of repose (tilt method) is 63 degrees, and the bulk density is 0.
It was 56g/cc.

[Effects of the Invention] The spherical oxalic acid deposits of the present invention have high purity, large bulk density, and good fluidity, so they are suitable for electronic materials and ceramics, and can also be used as raw materials for rare earth sulfides and halides. Because of its excellent properties, its industrial value is extremely large.

[Brief explanation of drawings]

FIG. 1 is a scanning electron micrograph (SE
M). FIG. 2 is a diagram showing the particle size distribution of yttrium oxalate produced by the method of Example 1 of the present invention. 3.4.5 shows examples 2 and 3, respectively. 1 is a scanning electron micrograph (SEM) of the particle structure of yttrium oxalate produced by the method of Comparative Example 1. Tuna ml Mackerel ← Sea bream

Claims (2)

[Claims] (1) Non-agglomerated spherical crystalline oxalic acid rare earth having an average particle size of 200 μm or less. (2) A method for producing rare earth oxalate by reacting rare earth ions and oxalate ions, characterized in that the temperature is maintained at 20°C or less from the start of the reaction until the obtained rare earth oxalate particles are obtained. Method for producing crystalline rare earth oxalate.