JPS61215217A - Purification of zirconium oxy-salt - Google Patents

Abstract

PURPOSE:To obtain a high-purity zirconium oxy-salt, by mixing an aqueous solution of rude zirconium oxy-salt with an alkali, separating the precipitated zirconium hydroxide and recrystallizing the hydroxide in an acidic liquid. CONSTITUTION:An aqueous solution of a crude zirconium oxy-salt such as zirconium oxychloride is mixed with an alkaline aqueous solution such as ammonia water, and the pH of the mixture is adjusted to 2-9 to precipitate zirconium hydroxide. The precipitate is separated, dispersed in an acidic solution such as hydrochloric acid and recrystallized by cooling or concentration. A purified zirconium oxy-salt having low concentration of impurities such as alkali metal, etc., and decreased content of impurities such as silica, iron, etc., can be produced by this process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for purifying zirconium oxy salt.

[Conventional technology]

Zirconium oxysalts are used as textile treatment agents, paint drying agents, raw materials for metal soaps, refractory binders, catalyst additives, ion exchangers, etc. In addition, purified zirconium oxysalt can be used as a raw material for high-purity zirconium oxide by thermal decomposition as it is, or by other methods such as coprecipitation and hydrolysis. It is known that when calcium, magnesium, yttrium, etc. are added to zirconium oxide as a stabilizer, it prevents the phase transition from occurring. The sintered body has been obtained with extremely high mechanical strength, and its application as a structural material in various fields is being studied.

Although zirconium nonaoxide has excellent properties similar to phosphorus, it has the disadvantage that its mechanical strength as a sintered body varies widely, which is an obstacle in practical use. The causes of this variation include particle size problems such as uneven raw material particle size, but there are also many problems with the purity of the thick material such as the occurrence of dislocation due to the presence of impurities and abnormal particle growth. Extremely high standards are required. Therefore, zirconium oxy salt, which is the starting material for zirconium monoxide, is also required to be highly pure.

Conventionally, zirconium oxysalts have been purified simply by recrystallization, but recrystallization alone is insufficient for purification, and if this is used as a raw material for zirconium oxide, there is a risk of causing the above-mentioned problems. Ta.

For this reason, there has been a desire to develop a method for obtaining even higher purity zirconium oxy salts.

[Problem that the invention seeks to solve]

An object of the present invention is to eliminate such conventional drawbacks and provide a method for obtaining a zirconium oxy salt that does not cause the above-mentioned problems even when used as a raw material for zirconium oxide.

[Means for solving problems]

That is, in the method of the present invention, an aqueous solution of a crude zirconium oxysalt and an alkaline aqueous solution are mixed, adjusted to a concentration of 2 to 9 to produce a precipitate of zirconium hydroxide, and then separated, and the resulting zirconium hydroxide This is a method for purifying a zirconium oxy salt, which comprises dispersing the zirconium oxy salt in an acidic solution to obtain a zirconium oxy salt solution, followed by recrystallization and separation by cooling or concentration.

The crude zirconium oxy salts used in the present invention include zirconium oxychloride c Zr0C22-8) (20)t zirconium oxynitrate (Zr0(No3), -2H20), zirconium oxyphosphate (Zr0(H2PO4)2) toxyacetic acid Zirconium (ZrO(0M3Co,), -H
2O'), etc. These salts can be used as aqueous solutions, with concentrations ranging from low concentrations to saturated solutions.
In order to quickly separate water-soluble impurities, it is convenient that the concentration is not too high, and the concentration of zirconium oxy salt is 0. O1 to 1.0 mol/L is good, and more preferably 0.05 to 0.5 usol/A. When an alkaline aqueous solution is added dropwise while stirring, zirconium hydroxide precipitates when - becomes 2 or more, and up to around pH 9, precipitation occurs in proportion to the added alkaline aqueous solution, but - becomes 9 Exceeding this will only increase the alkali concentration and will hardly increase the production of zirconium hydroxide. The alkaline aqueous solution used is preferably one that easily reacts with the zirconium oxy salt to produce zirconium hydroxide and as a by-product a salt with high solubility in water. For example, ammonia, sodium hydroxide, potassium hydroxide.

Aqueous solutions such as lithium hydroxide, and pyridine.

Aqueous solutions of organic basic compounds such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine are used. In the case of zirconium oxychloride, aqueous ammonia or organic basic compounds are more preferred. The precipitate of zirconium hydroxide thus produced is separated from the solution by a conventional method such as filtration or centrifugation. At this time, separating as much free water as possible helps improve purity and recovery rate.

However, water is removed by heating in a subsequent reaction.
This is not preferred because it creates insoluble substances such as rO□. Next, this precipitate is mixed with an aqueous solution of an acid containing a conjugate base to form the desired purified zirconium oxy salt, and a reaction is carried out. In this case, in order to increase the recovery rate, it is convenient to have a high acid concentration, and the order of mixing may be either placing the precipitate in the acid solution or vice versa. It is desirable to stir K in order to make the reaction proceed more quickly, and to heat it in order to facilitate the subsequent recrystallization operation. Also, one way to increase the recovery rate of the target product is to evaporate the solvent, but care must be taken as this also results in an increase in the concentration of impurities in the solution. Once the solids have completely dissolved (the solution becomes clear), allow it to cool for recrystallization. Note that if crystal growth of the zirconium oxy salt is not desired or if the processing time is desired to be shortened, there is a method of rapidly cooling to precipitate microcrystals. In this case, there is a risk that the purity will be reduced to some extent compared to when recrystallization is performed due to poor separation of the crystals and solution, but by carefully washing the precipitate, the amount of dull substances can be reduced. Furthermore, in order to improve the recovery rate from the solution, it is also effective to reduce the solubility by cooling the solution to near the freezing point. When sufficient crystals have precipitated, the solution is separated by suction filtration, centrifugation, etc. If a highly pure zirconium oxysalt is desired, the separated crystals are washed with acid.

The zirconium oxy salt obtained by the above method contained much less impurities such as alkali metals, and also contained less impurities such as silica and iron than those conventionally purified by mere recrystallization. The effects of this method will be explained below using examples.

Example 1 Sodium zirconate (Na2Zr03) 100 S' prepared from vaterite (Z ro2 ) was reacted with concentrated hydrochloric acid 200-, and water 7001R1 was added to give about 0.
A crude aqueous zirconium oxychloride solution of 5 molμ was obtained. 30 d of 25% ammonia water was added to this aqueous solution to form a white precipitate as -2. The obtained precipitate was suction filtered and washed with 5QQm of water on a funnel.

Next, after thoroughly removing water from the precipitate, the precipitate was transferred to a beaker, concentrated hydrochloric acid 5001 was added thereto, and the mixture was heated with thorough stirring. When the solution becomes clear, stop heating and let it cool. After cooling the solution to room temperature, the crystals were separated by suction filtration. Table 1 shows the analysis results of the obtained purified zirconium oxychloride.

Example 2 From a heated reaction of zircon (ZrSi04) and sodium hydroxide, sodium silicate was eluted (by water treatment) and sodium zirconate (Na2Z ro
5) was obtained. The sodium zirconate 100y
- was reacted with 200 d of concentrated hydrochloric acid, and 700 d of water was added to obtain an approximately 0.5 mol/l crude zirconium oxychloride aqueous solution. 120 d of Nigiri gin was added to this aqueous solution and the volume was adjusted to 9 to form a white precipitate.

The analysis results of zirconium oxychloride obtained by treating this precipitate in the same manner as in Example 1 are shown in Table IK.

Example 3 Sodium zirconate A (
Na2ZrO, ) 100 S' was reacted with concentrated nitric acid 13014, and water 700114 was added to obtain a crude zirconium oxynitrate aqueous solution of about 0.5 not/l. To this aqueous solution, add 10117% of 50% sodium hydroxide aqueous solution, and after stirring well, add 7017% of 25% aqueous ammonia to pH 4-5.
A white precipitate was formed. This was then suction-filtered and the precipitate was washed with water. After thoroughly removing moisture from the precipitate, the precipitate was transferred to a flask, 330 d of concentrated nitric acid was added, and the precipitate was heated with thorough stirring. When the solution became transparent, the pressure was reduced to evaporate the solvent, and when crystals precipitated, the pressure reduction and heating were stopped and the solution was allowed to cool to room temperature.

This solution was suction filtered to separate the crystals. Table 1 shows the analysis results of the obtained zirconium oxynitrate.

Example 4 Sodium silicate was eluted from a mixture of zircon (Sin2 Z ro 2 ) and sodium hydroxide by water treatment, and sodium zirconate (Na
2ZrO,) was obtained. The sodium zirconate 1
ooy as a saturated aqueous solution of orthophosphoric acid (H, PO4)
d and 700 ml of water was added to obtain a crude zirconium oxyphosphate aqueous solution. Add 60% potassium hydroxide to this aqueous solution.
A white precipitate was formed as y-addition 9. The precipitate was suction filtered and washed with 1000 m+7 water on a planar funnel. Next, after thoroughly removing the moisture from the precipitate,
Transfer this to a flask and prepare a saturated solution of 6
011j was added and heated while stirring well. When the solution became transparent, the solvent was evaporated by reducing the pressure, and when crystals were precipitated, the vacuum and heating were stopped and the solution was allowed to cool to room temperature. The solution was vacuum-filtered to separate the crystals. Table 1 shows the analysis results of the obtained zirconium oxyphosphate.

Example 5 Sodium zirconate (1
00P) with glacial acetic acid 601117 to form water'yooy
was added to obtain a crude zirconium oxyacetate aqueous solution. Add 80 - saturated solution of lithium hydroxide to this aqueous solution and make 6 -
8, a white precipitate was produced. Next, this was filtered under suction, and the precipitate was washed with 500μ of water. After thoroughly removing moisture from the precipitate, transfer it to a flask and add 100 d of glacial acetic acid.
was added and heated while stirring well. When the solution became transparent, the pressure was reduced to evaporate the solvent, and when crystals precipitated, the pressure reduction and heating were stopped and the solution was allowed to cool to room temperature. This solution was filtered to separate the crystals. The analysis results of the obtained zirconium nineoxyacetate are shown in Table 1.

Comparative Example 1 (Conventional method) Sodium zirconate (NazZr03) 1001F prepared from Baddeleyte (Z ro□) was dissolved in concentrated hydrochloric acid 2
After reacting with 0011j and removing insoluble impurities by filtration, the solution was heated and concentrated to precipitate crystals of zirconium oxychloride. After cooling to room temperature, the crystals were separated by suction filtration, the obtained crystals were dissolved in water, concentrated hydrochloric acid was added to form a precipitate, the precipitate was completely dissolved by heating, and the mixture was allowed to cool to room temperature for recrystallization. . The precipitated crystals were separated from the solution by suction filtration. The analysis results of the obtained zirconium oxychloride are shown in Table IK.

Comparative Example 2 (Conventional Method) From a mixture of zircon (ZrSiO4) and sodium hydroxide reacted by heating, sodium silicate was eluted by water treatment to obtain sodium zirconate.

Table 1 shows the analysis results of zirconium oxychloride obtained by treating this sodium zirconate in the same manner as in Comparative Example 1.
It was shown to.

Claims (1)

[Scope of Claims] 1) Mix an aqueous solution of crude zirconium oxysalt with an alkaline aqueous solution, adjust the pH to 2 to 9 to produce a precipitate of zirconium hydroxide, and then separate the resulting zirconium hydroxide. A method for purifying a zirconium oxy salt, which comprises dispersing the zirconium oxy salt in an acidic solution to obtain a zirconium oxy salt solution, recrystallizing the solution by cooling or concentrating, and then separating the solution. 2) The method for purifying a zirconium oxysalt according to claim 1, wherein the crude zirconium oxysalt is zirconium oxychloride, zirconium oxynitrate, zirconium oxyphosphate, or zirconium oxyacetate. 3) The method for purifying a zirconium oxy salt according to claim 1, wherein the alkaline aqueous solution is ammonia, sodium hydroxide, potassium hydroxide, lithium hydroxide, or an organic base compound. 4) The method for purifying a zirconium oxy salt according to claim 1, wherein the acidic solution is hydrochloric acid, nitric acid, phosphoric acid, or acetic acid.