JPH0632618A - Purification of metal chloride - Google Patents

Abstract

PURPOSE:To easily obtain a high-purity chloride at a low cost from a metal chloride containing impurities such as iron, cobalt and copper without using hydrochloric acid. CONSTITUTION:A metal chloride containing a small amount of impurity is dissolved in water at a concentration to attain a chlorine ion concentration of >=6mol/L and the impurities in the metal chloride are separated by extracting with a solvent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating and removing a trace amount of impurities contained in a metal chloride to obtain a high-purity metal chloride.

[0002]

2. Description of the Related Art Conventionally, a high-purity metal chloride is obtained by separating and removing impurities such as iron, cobalt, and copper contained in a trace amount of 50 to 100 ppm in a metal chloride such as nickel chloride and aluminum chloride. As a method for obtaining the above, for example, a method in which a metal chloride is dissolved in an aqueous hydrochloric acid solution to convert impurities into a chloride complex and then the impurities are adsorbed to an anion exchange resin is generally used.

[0003]

However, in the method using hydrochloric acid, the impurities contained in the hydrochloric acid are not removed by the ion exchange resin, so that the metal chloride is contaminated and the hydrochloric acid is used in the subsequent step of the ion exchange operation. Has the drawback that it must be removed. On the other hand, when using high-purity hydrochloric acid distilled and purified by infrared heating or the like, there are drawbacks such that the cost of hydrochloric acid is high and the danger during the work is high.

An object of the present invention is to provide a method for easily purifying metal chlorides to high purity at low cost without using hydrochloric acid.

[0005]

According to the present invention, a metal chloride containing a trace amount of impurities has a chloride ion concentration of 6 mol / l.
As described above, it is characterized in that impurities in the metal chloride are separated by the organic solvent method after being dissolved in water. Further, in the method of the present invention, nickel chloride, aluminum chloride and the like can be mentioned as metal chlorides, and iron, cobalt, copper or metal ions of two or more of these can be used as impurities.

[0006]

According to the present invention, since a trace amount of impurities contained in metal chlorides is chloride, when the metal chlorides are dissolved in water, the impurities are easily dissolved in water to form chlorides. It was discovered from the fact that it becomes a substance complex. For example, as shown in FIG. 1, a trace amount of iron contained in nickel chloride is more easily extracted into the organic solvent layer as the chloride ion concentration in the nickel chloride aqueous solution becomes higher, and the chloride ion concentration is 6 mol / l or more. In the range of, the extraction is extremely high.

In addition, according to the method of the present invention, impurities can be separated and removed with high efficiency from a high-concentration metal chloride aqueous solution. The metal chloride can be easily obtained. Nickel and aluminum are preferable as the metal chlorides that dissolve in water when the chlorine ion concentration is in the range of 6 mol / l or more, and as the impurities that are easily dissolved and separated in water,
Iron, cobalt and copper are preferred.

[0008]

EXAMPLE Nickel chloride and ferric chloride were used as chlorine ion concentrations of 2 mol / l, 4 mol / l, 6 mol / l, and
8 mol / l and iron concentration of 50 p each
It was dissolved in water to pm. 20m from each solution
l was collected in a separating funnel, 10 ml of methyl isobutyl ketone was added thereto, and the mixture was shaken for 2 minutes and allowed to stand for 10 minutes to obtain two layers of an organic layer and an aqueous layer. After removing the water layer,
Pure water was added to the organic layer and shaken to back extract iron into the aqueous layer. The iron back-extracted in the aqueous layer was measured by absorptiometry, and after confirming that the iron in the organic layer was completely back-extracted, the removal rate of iron in the nickel chloride aqueous solution was determined to be 3 each. %, 26%, 86%, 93%. The results are shown in FIG.

It can be seen from FIG. 1 that the removal rate of iron as an impurity is significantly increased when the chloride ion concentration in the nickel chloride aqueous solution is in the range of 6 mol / l or more. Similar results are obtained when using aluminum chloride instead of nickel chloride,
Similar results were obtained when cobalt, copper or two or more kinds of metal ions were used instead of iron.

[0010]

According to the present invention, trace amounts of iron, cobalt,
A high-purity metal chloride can be easily obtained at low cost from a metal chloride containing copper or the like.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the concentration of chlorine ions in a nickel chloride solution and the percentage of iron removed according to the present invention.

Claims (2)

[Claims] 1. A metal chloride containing a trace amount of impurities,
A method for purifying a metal chloride, which comprises dissolving impurities in water so that the chloride ion concentration is 6 mol / l or more and then separating impurities in the metal chloride by a solvent extraction method. 2. The purification method according to claim 1, wherein the metal chloride is nickel chloride or aluminum chloride, and the impurities are iron, cobalt, copper, or a metal ion of two or more kinds thereof.