JPH05155615A - Production of acicular barium carbonate - Google Patents

Abstract

PURPOSE:To obtain acicular barium carbonate having satisfactory crystallinity controlled to 10-100mum average particle diameter. CONSTITUTION:An aq. soln. of water-soluble barium salt and an aq. soln. of alkali carbonate are simultaneously added to water in a reactor from separate feed holes and the rate of addition of the water-soluble barium salt to the water is regulated to 0.01-0.1mol/hr.L (expressed in terms of pure barium salt). In the reactor, acicular barium carbonate is produced.

Description

Detailed Description of the Invention

[0001]

[Industrial application] Average grain size with good crystallinity, which is useful as a raw material for optical glass and electro-ceramics 10
Provided is a method for producing needle-shaped barium carbonate having a particle size of 100 μm.

[0002]

Prior art barite (BaSO ₄ , barite) is reduced and roasted,
Carbon dioxide gas is blown into the barium sulfide solution obtained by leaching the roasted product with hot water to precipitate barium carbonate. The barium carbonate obtained by this method is a fine powder having an average particle size of 10 μm or less and poor flowability. Is.

[0003]

SUMMARY OF THE INVENTION The present invention is intended to provide a method for producing needle-shaped barium carbonate having good crystallinity and an average particle size of 10 to 100 μm, which has not been obtained by the conventional method.

[0004]

Means for Solving the Problems The present inventor
In order to obtain acicular crystal barium carbonate having a size of 100 μm and good crystallinity, as a result of detailed examination of the crystal growth conditions of barium carbonate, the present invention has been reached, the gist of which is an aqueous solution of a water-soluble barium salt. And the aqueous solution of alkali carbonate are simultaneously added to the water in the reaction vessel from different supply ports,
The addition rate of the water-soluble barium salt aqueous solution was 0.01 to 0.1 mol / hr · L as a pure barium salt with respect to the amount of water.
(Hereinafter, liter is referred to as L), which is a method for producing needle-shaped barium carbonate.

The present invention will be described in detail below. Although there are various methods of adding the raw material water-soluble barium salt aqueous solution and the alkali carbonate aqueous solution, it was found that the simultaneous addition of both aqueous solutions had the greatest effect on the crystal growth of acicular barium carbonate.
Fine crystals are obtained by a method of preliminarily charging a water-soluble barium salt aqueous solution in a reaction vessel and adding an alkali carbonate aqueous solution or a method of preliminarily charging an alkali carbonate aqueous solution in a reaction vessel and adding a water-soluble barium salt aqueous solution. Absent. In addition, it is also inconvenient to form fine crystals by a method in which either one is first supplied into the water in the reaction vessel from different supply ports and the other is supplied later. The addition rate of the water-soluble barium salt aqueous solution is 0.01 to 0.1 mol / hr · L, preferably 0.01 to 0.05 mol / hr · L, as a pure barium salt with respect to the amount of water charged in the reaction vessel. ..
If it is faster than 0.1, the crystal sizes become uneven, which is not preferable, and if it is slower than 0.01, the productivity is extremely lowered, which is not preferable.

The addition rate of the aqueous solution of alkali carbonate is 1.0 to 1.0 which is equivalent to pure barium salt as pure alkali carbonate.
1.2 times is preferable. The reaction temperature is preferably 35 to 70 ° C, and the higher the temperature, the larger the crystals obtained.
If it exceeds, the effect on crystal growth will decrease,
If it is lower than 35 ° C, fine crystals are likely to be formed. After crystallization of the barium carbonate salt crystal, the crystal is filtered, washed with water and dried to obtain needle-shaped barium carbonate having an average particle size of 10 to 100 μm. Examples of the raw material water-soluble barium salt used here include barium nitrate and barium chloride, and examples of the alkali carbonate include sodium carbonate, potassium carbonate, sodium hydrogen carbonate and the like.

[0007]

EXAMPLES The embodiments of the present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. (Example 1) Barium nitrate 17.0 g (0.065 mol) aqueous solution
While stirring 500 ml and 500 ml of an aqueous solution of ammonium hydrogen carbonate 12.6 g (0.16 mol: 1.2 times equivalent to barium nitrate) in 750 ml warm water heated to 40 ° C in a 2 L beaker with a stirrer, 130 at the same flow rate. Added simultaneously over minutes. At this time, the addition rate of barium salt was 0.04 mol / hr with respect to the volume of water initially placed in the beaker.
・ It was L. Further, during the reaction, the reaction temperature was controlled so as to be kept at 40 ° C. The formed barium carbonate-containing slurry was filtered and washed with water, and the obtained precipitate was dried at 90 ° C. for 16 hours. A scanning electron microscope (hereinafter referred to as SEM) photograph of the dried product is shown in FIG. Needle-shaped barium carbonate having an average particle size of about 50 μm and a regular grain shape was obtained.

(Example 2) Barium carbonate was synthesized in the same manner as in Example 1 except that the reaction temperature was controlled to 60 ± 3 ° C. The SEM photograph of the dried product is shown in FIG. Average particle size about 100
Needle-shaped barium carbonate having a regular particle size of μm was obtained.

(Example 3) Barium carbonate was synthesized in the same manner as in Example 1 except that the reaction was carried out at room temperature (26 ° C).
A SEM photograph of the dried product is shown in FIG. The average length is about 30 μm,
A slightly agglomerated acicular barium carbonate was obtained.

Comparative Example 1 Barium carbonate was prepared in the same manner as in Example 1 except that the addition time of the barium nitrate aqueous solution and the ammonium hydrogen carbonate aqueous solution was 40 minutes (the addition rate of the barium salt was 0.13 mol / hr.L). Was synthesized. A SEM photograph of the dried product is shown in FIG. Barium carbonate, which was needle-shaped, but was irregular in size and was agglomerated hard, was obtained.

[0011]

EFFECTS OF THE INVENTION According to the present invention, acicular crystal barium carbonate having an average grain size of 10 to 100 μm and good crystallinity can be obtained.

[Brief description of drawings]

FIG. 1 is an electron micrograph showing the particle shape of barium carbonate obtained in Example 1 of the present invention.

FIG. 2 is an electron micrograph showing the particle shape of barium carbonate obtained in Example 2 of the present invention.

FIG. 3 is an electron micrograph showing the particle shape of barium carbonate obtained in Example 3 of the present invention.

FIG. 4 is an electron micrograph showing the particle shape of barium carbonate obtained in Comparative Example 1.

Claims (1)

[Claims] 1. An aqueous solution of a water-soluble barium salt and an aqueous solution of an alkali carbonate are simultaneously added into water in a reaction vessel from different supply ports, and the addition rate of the water-soluble barium salt is a pure barium salt with respect to the amount of water. 0.01-0.1 mol /
The method for producing needle-shaped barium carbonate is characterized in that it is hr · L.