JPS5930719A - Manufacture of aluminum hydroxide or oxide having low content of radioactive element - Google Patents

Abstract

PURPOSE:To manufacture aluminum hydroxide or oxide having a low content of radioactive elements by using a soln. of an Al compound obtd. by treatment with a chelate compound as a starting material. CONSTITUTION:A chelating agent capable of separating radioactive elements such as U and Th contained in an Al compound from a soln. of the compound by chelate bonding is used. The chelating agent such as triphenylphosphine or resin having phosphoric acid groups is brought into contact with a soln. of an Al compound such as a soln. of sodium aluminate in an org. solvent to remove radioactive elements by adsorption, and aluminum hydroxide or oxide is formed by conventional methods such as neutralization, hydrolysis and calcination. The Al compound soln. is preferably brought into contact with the chelating agent by passing the soln. through a tower packed with the agent.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing aluminum hydroxide or oxide having a low content of radioactive elements. More specifically, we use a chelating agent to separate radioactive elements in an aqueous solution or an organic solvent solution (hereinafter referred to as a solution) containing an aluminum compound by adsorption and removal of the chelate.
Aluminum hydroxide or oxide (hereinafter referred to as alumina) with extremely low radioactive element content suitable for semiconductor materials.

).

In semiconductor memory devices, in order to increase the degree of integration of memory circuits, it is necessary to reduce the size of each memory cell as much as possible, which inevitably reduces the amount of charge stored in each cell. The smaller the amount of accumulated charge, the more likely the memory function will be impaired by various external disturbances.
Memory errors are starting to become noticeable.

The main cause of soft errors in dynamic random access memories and charge-coupled devices is α-rays emitted as a result of the nuclear decay of U and Th, which are left behind in the sintered alumina container housing the IC chip. It is said.

On the other hand, α per atom emitted during the decay process of U and Th
- Linear particles, 8 U238, 7 U2g+5, T
There are 6 h. Therefore, most of the normal alumina linear particles are derived from U.

Therefore, in order to further increase the degree of integration of memory circuits, it is necessary to keep the capacitance of U and Th contained in alumina 1 used in the IC chip storage container as low as possible.

Commercially available ordinary alumina contains U from 0.5 to jppm.

n is 0.025-0.05 ppm 8! Contains a lot of water.

Conventionally, in order to obtain alumina with less a-radiator, a ferromagnetic composite adsorbent obtained by impregnating fine particles of porous T'620 with titanium impropoxide and then hydrolyzing it was used to absorb U in a sodium aluminate solution. (1980 Ceramics Association Annual Meeting Preliminary Lecture Collection, p. 130), a method of adding aluminum fluoride and/or boric acid and silicon oxide-containing particles to alumina particles, mixing and firing (Japanese Unexamined Patent Publication No. 1982 -155
016 Publication), a method in which lightly calcined alumina particles are immersed in a dilute mineral acid solution to elute radioactive elements into the mineral acid solution, and then the alumina particles are separated from the mineral acid solution (Japanese Unexamined Patent Publication No. 5
6-155017) etc. have been proposed.

However, the alumina obtained by any of the above methods has a high radioactive element content, which is desirable for semiconductor materials.]
It has not reached a level below Oppb order, and is not industrially satisfactory.

In view of these circumstances, the inventors of the present invention aimed to produce alumina in which the radioactive element content was removed to a level sufficient to withstand use as a semiconductor material. The present inventors have discovered that the method of the present invention is effective in adsorbing and removing radioactive elements in solutions of aluminum compounds.

That is, the present invention is characterized in that a solution of an aluminum compound containing a trace amount of a radioactive element is brought into contact with a chelating agent to adsorb and separate the trace amount of the radioactive element, and then aluminum hydroxide or oxide is produced from the solution. An object of the present invention is to provide a method for producing aluminum hydroxide or oxide having a low radioactive element content.

The chelating agent used in the present invention is not particularly limited as long as it can chelate with the radioactive element contained in the aluminum compound and can be separated from the aluminum compound solution.

Such chelating agents include organic phosphorus compounds such as triphenylphosphine, tricresylphosphine, diphenylphosphonate, diethylphosphonate, dimethylphenylphosphonate, di(2-ethylhexyl)phosphoric acid, trioctylphosphine, and 1,2-dioxy- 9,10
-Anthraquinone, 1,2,5,8-tetraoxy-9
, anthraquinone derivatives such as 10-anthraquinone, 7-
'(5,5,7,7-tetramethyl-1-octene-3
-yl)-8-hydroxyquinoline, 7-zocanyl-8
-quinoline derivatives such as hydroxyquinoline; macrocyclic compounds such as 27-crown-9, 24-crown-8, 3, 4
-dipropyl-octanamide oxime, dodecane amidoxime, tetradecane amidoxime, 4-dodecylbenzamide oxime, 4-octanylbenzamide oxime, 4-(3゜3.5.5-f tramethyl-hexylne-benzamide oxime, 4-dodecyl Amidoxime derivatives such as -benzylamino-(N-methanediamidodioxime), 4-decanyl-benzylamino-(N-methanediamidoxime); phosphoric acid group, aminoalkylene phosphoric acid group, amidoxime group, hydrazino group, oxime group, Examples include chelate resins having functional groups such as polyethylene polyamino groups, hydrazino groups, hydroxyamino groups, aminocarboxylic acid groups, and iminodicarboxylic acid groups.

However, it was completely unexpected that alumina with a lower radioactive element content could be produced by using a chelating agent compared to methods using conventionally known ferromagnetic composite adsorbents.

In carrying out the method of the present invention, the solutions of aluminum compounds to be brought into contact with the chelating agent include sodium aluminate, potassium aluminate, aluminum sulfate, alum,
Water, alcohol, ether, carbon tetrachloride solutions of inorganic aluminum compounds such as ammonium aluminum carbonate, aluminum sulfate, aluminum chloride, ammonium aluminum sulfate, organic aluminum compounds such as aluminum isopropoxide, aluminum ethoxide, aluminum [-butoxide, etc. An organic solvent solution containing an organoaluminum compound such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, benzene, or hexane is used.

In carrying out the present invention, the contact between the chelating agent and the aluminum compound solution may be carried out under appropriately selected conditions.

The contact method is not particularly limited, and includes a method in which a liquid or solid chelating agent is added to a solution of an aluminum compound and a contact treatment is carried out by stirring or shaking, and a method in which a helium compound is contained in a column filled with a chelating agent. A method such as passing a solution is generally adopted.

However, from the viewpoint of processing operations, a method of passing a solution of an aluminum compound through a tank filled with a chelating agent is preferably employed.

In carrying out the method of the present invention, the amount of chelating agent used and the contact time are not particularly limited, and the concentration of radioactive elements in the solution of the aluminum compound to be treated, the type of solution of the aluminum compound, the chelate used, etc. Although it varies depending on the type of curing agent, it can be set by conducting appropriate preliminary experiments.

The amount of the chelating agent to be used is 5 times the mole or more, preferably 50-3000 times the mole of the chelating agent having a radioactive element adsorption functional group per 1.2 atoms of the radioactive element in the solution of the aluminum compound. The contact time is generally 1 minute to 24 minutes.
All you have to do is keep them in contact for a while. The contact temperature between the chelating agent and the solution of the aluminum compound is not particularly limited, but it is usually carried out at a temperature of 0 to 100°C.

The aluminum compound solution with a low radioactive element content from which radioactive elements have been adsorbed and removed by the method of the present invention is then subjected to known methods such as neutralization, hydrolysis, calcination, etc. to form aluminum hydroxide or oxide. The alumina thus obtained usually has a radioactive element content of 0.
The O content can be 5 ppm or less, preferably about 0.01 ppm or less.

In addition, the chelating agent chelated with the radioactive element used in the method of the present invention is separated from the aluminum compound solution and then contacted with hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, etc. to melt the radioactive element from the chelating agent and reuse it. can do.

According to the method of the present invention as detailed above, alumina with a low concentration can be obtained using a known method for producing alumina with a low content of radioactive elements, and its industrial value is great for semiconductor materials and the like.

The method of the present invention will be explained in more detail below with reference to examples, but the present invention is not limited to the following examples unless the gist thereof is exceeded.

Example j Chelate resin Sumikire) MC-9 having a polyethylene polyamino methylene phosphate group in 1000 parts by volume of solution
0 (manufactured by Sumitomo Chemical Co., Ltd., trade name) was added in an amount of 300 parts, and the mixture was shaken for 3 hours to perform treatment with a chelating agent. The treated solution was filtered to produce a chelate upper treated sodium aluminate aqueous solution. Adding 33 parts by volume of 30% by weight hydrochloric acid to 100 parts by volume of this sodium aluminate aqueous solution treated with other chelating agents,
It was neutralized to produce aluminum hydroxide. The uranium content in the aluminum oxide obtained by firing the obtained ° aluminum hydroxide at 900 to 1200 °C for 6 hours is o, oos pp
It was m.

Examples 2 to 6 A sodium aluminate aqueous solution was treated in the same manner as in Example 1 except that the following five types of chelate resins were used in place of the chelate resin in Example 1, and the U concentration was the first. The results shown in the table were obtained.

Duolite C5-346 (manufactured by Diamond Jamrock Co., Ltd., trade name) (Chelate resin having an amidoxime group of 3.2 mol/l-ffd fat) Duolite ES-467 (manufactured by Diamond Jamrock Co., Ltd., trade name) [1 , 5 mol/l-resin aminomethylene phosphate group-containing chelate resin] I-triphenyl phosphate skeleton obtained by condensation reaction of 111 parts by weight of formalin and 45 superpositioned parts of resorcin, 1.3 mol/l-resin containing chelate resin d0 Chelate resin B 2.4'/m mol 7 g - 101 parts of diethylenetriaminated styrene-divinylbenzene resin containing diethyltriamine, !:, 0 obtained by reaction with 14 parts by weight of 5-bromo-8-hydroxyquinoline ,
99 mol// - Chelate resin having 8-hydroxyquinoline pendant in the resin.

Chelate resin C 4.1m obtained by reaction of 66 parts by weight of acrylonitrile-divinylbenzene resin with a degree of crosslinking IQmo 1%, 66 parts by weight of hydroxylamine and 16 parts by weight of hydrazine
ol/1-amide oxime group of resin, 1.0 mol/z
- A chelate resin having an imino group of a resin and a hydrazino group of l, Qmol/l - a resin.

Table 1 [・Example Example 7 Uranium concentration 0. 1000 parts by volume of an isopropyl alcohol solution of 60% O3ppm aluminum isopropoxide was added to 1.5 parts of polyethylene polyamino methylene phosphate group.
mol//-resin-containing chelate [fat sumichelate M
The solution was passed through a column filled with parts by volume of C-90500 for 1 hour to perform treatment with a chelating agent.

100 parts by weight of isopropyl alcohol solution of aluminum isoproboxide treated with other chelating agents Il! 16 parts by weight of water was added and hydrolyzed to produce aluminum hydroxide. The obtained aluminum hydroxide is 800 to 11
The uranium content in the aluminum oxide obtained by firing at 00°C for 4 hours was 0°0005 ppm or less.

Examples 8 to 12 When the chelate resin shown in Table 2 was treated with the aluminum compound solution shown in Table 2 in the same manner as in Example 7, the U concentration was as shown in Table 2. The result was

Example 13 Uranium L3 PP” containing A/20.93!/11
500 parts by weight of 3,4-dipropyl-octanamide oxime as a xylating agent and 500 parts by weight of petroleum ether as a solvent were added to 1000 parts by weight of an aqueous solution of sodium aluminate of Na20173F//, and after shaking for 1 hour, the liquids were separated. , an aqueous sodium aluminate solution with chelate upper side treatment was prepared.

61 parts by volume of 30% by weight hydrochloric acid was added to 100 parts by weight of an aqueous solution of sodium aluminate treated with other chelating agents to neutralize it, thereby producing aluminum hydroxide.

The uranium content in the aluminum oxide obtained by firing the obtained aluminum hydroxide at 900 to 1,200° C. for 6 hours was 0.005 ppm.

Examples 14 to 16 A solution of an aluminum compound was treated in the same manner as in Example 13, except that the type of chelating agent was changed. The U concentration in the obtained aluminum oxide was as shown in Table 3.

Table 3

Claims (1)

[Claims] 1) A solution of an aluminum compound containing a trace amount of radioactive element is brought into contact with a chelating agent to adsorb and separate the trace amount of radioactive element, and then aluminum hydroxide or oxide is produced from the solution. A method for producing aluminum hydroxide or oxide having a low content of radioactive elements. 2) The radioactivity according to claim 1, wherein the solution of aluminum and the compound is an aqueous solution of sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum chloride, etc. or an organic solvent solution of an alkoxyaluminum compound. A method for producing aluminum hydroxide or oxide with low elemental content. 3) The method for producing aluminum hydroxide or oxide with a low radioactive element content according to claim 1, wherein the chelating agent is a compound consisting of a functional group that forms a chelate bond with uranium. 4) Production of aluminum hydroxide or oxide with a low content of radioactive elements according to claim 3, wherein the inhibitor is a resin insoluble in a solution containing an aluminum compound. Method. 5) The chelating agent is a compound having a functional group consisting of aminoalkylene phosphoric acid, phosphoric acid, amidoxime, hydroxyquinoline, alkylphosphine, alkylphosphine oxyto, polyether, aminocarboxylic acid, iminocarboxylic acid, and derivatives thereof. A method for producing aluminum hydroxide or oxide having a low content of radioactive elements according to claim 1. 6) The method for producing aluminum hydroxide or oxide with a low radioactive element content according to claim 5, wherein the chelating agent is a resin having an aminoalkylene phosphate group.