JPS5939719A - Manufacture of high purity lithium carbonate - Google Patents

Abstract

PURPOSE:To obtain simply and efficiently high purity lithium carbonate suitable for use as a material for the optical industry by converting a crude lithium compound into lithium perchlorate, recrystallizing the lithium perchlorate, and reacting it with carbon dioxide in the presence of ammonia. CONSTITUTION:A crude lithium compound such as industrial lithium carbonate, industrial lithium hydroxide or industrial lithium oxide is dissolved in an aqueous soln. of perchloric acid. The resulting soln. is concentrated or merely cooled to crystallize and separate lithium perchlorate. The lithium perchlorate is recrystallized using water or an org. solvent such as ethyl ether to obtain high purity lithium perchlorate. The high purity lithium perchlorate is dissolved in pure water, the resulting soln. is made basic by adding ammonia, and carbon dioxide is blown into the basic soln. and reacted to precipitate high purity lithium carbonate. The high purity lithium carbonate is taken out by filtration.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing high purity lithium carbonate from a crude lithium compound.

Demand for high-purity lithium carbonate as a material for electronic and optical industries has increased in recent years. The lithium carbonate used in these materials requires extremely high purity, and conventional methods of producing high-purity lithium carbonate, such as recrystallization or reprecipitation, are not only extremely time-consuming but also have low yields. , Refining required considerable expense.

The present invention provides a method for easily and efficiently removing impurities contained in a crude lithium compound and producing high-purity lithium carbonate. Crystals of 1 cum perchlorate are crystallized and isolated by cooling or simply cooling, then recrystallized using water and/or organic solvents, and the crystals are then crystallized in a vocal medium under ammoniacal base. It consists of reacting with carbon dioxide.

The production method of the present invention is characterized by utilizing the unique properties of lithium perchlorate and purifying lithium at the stage of lithium perchlorate. Highly purified lithium carbonate is obtained by reacting with carbon dioxide under the same conditions.

The crude lithium compound used in the present invention includes, for example, industrial lithium compounds such as lithium carbonate, lithium 3 hydroxide, and lithium chloride, but industrial lithium carbonate is generally used.

To explain the method for producing high-purity lithium carbonate using industrial lithium carbonate, commercially available industrial lithium carbonate usually contains 99 or more as lithium carbonate,
It also contains trace amounts of salts such as potassium, sodium, magnesium, iron, and calcium as impurities. To obtain high purity lithium carbonate from this crude lithium carbonate,
First, the kernels are dissolved in, for example, 601% perchloric acid to make lithium perchlorate. The solubility of lithium perchlorate in water is neither large nor deceptively small, so it is favorable/convenient for the purpose of recrystallization and purification, and general perchlorates are superior to alkaline earth metal salts. Due to its high solubility in water, it can be purified very conveniently. When an aqueous solution containing lithium perchlorate is cooled or concentrated and cooled, lithium perchlorate precipitates in the form of trihydrate as relatively large crystals that are easy to handle. If this is separated by tF, washed with water, and dehydrated, lithium perchlorate of considerably high purity can be obtained. ζ If the thus obtained lithium perchlorate is repeatedly recrystallized using pure water, a trihydrate of lithium perchlorate with even higher purity can be obtained. Also, unlike other metal perchlorates, lithium perchlorate has a uniquely high solubility in organic solvents, especially ether, so if purified trihydrate is added to ethyl ether, for example, lithium perchlorate will dissolve into ether. Moving on to the layers,
Other impurities can be left in the aqueous layer for separation and purification.

In order to obtain highly purified lithium carbonate, the thus purified lithium perchlorate is dissolved in pure water, ammonia is added to make it basic, and carbon dioxide is blown in to precipitate lithium carbonate. At this time, heating can facilitate the formation of a precipitate. The ammonia and carbon dioxide to be used need to be as highly purified as possible; ammonia is preferably gaseous, and carbon dioxide is also preferably gaseous. The obtained crystals are washed with water, dehydrated, and dried to obtain high purity lithium carbonate.

Next, the present invention will be explained with reference to examples, but the gist thereof is not limited only to these examples.

In the examples, parts represent parts by weight.

Example 1 75 parts of industrial lithium carbonate were stirred in 650 parts of water, and 320 parts of 60% industrial perchloric acid was gradually added thereto. After the addition was complete, the mixture was stirred for about 15 minutes and then filtered. When the F solution was concentrated to a concentration of about 4 and allowed to cool, trihydrate of lithium perchlorate was precipitated. This was filtered, washed with water, and dehydrated using a centrifuge to obtain 220 parts of lithium perchlorate trihydrate, with a yield of 6B and 8%. The crystals were again put into 150 parts of pure water, stirred and dissolved, and then concentrated.
After cooling, highly purified lithium perchlorate was obtained.

Example 2 75 parts of industrial lithium carbonate were stirred in 650 parts of water, concentrated with 70% industrial perchloric acid 265, and allowed to cool to precipitate crystals of lithium perchlorate trihydrate. This was filtered and dehydrated using a centrifuge to obtain 250 parts of lithium perchlorate trihydrate.

The yield was 7a1.

Add 10 parts of pure water and 300 parts of ethyl ether to this, shake well and leave to stand, then separate the ether part,
Ether was removed under reduced pressure. After drying in a vacuum desiccator, 145 parts of lithium perchlorate was obtained. This was further poured into 150 parts of pure water and recrystallized to obtain highly pure lithium perchlorate trihydrate.

Example 3 160 parts of sufficiently purified lithium perchlorate trihydrate obtained by the method of Examples 1 and 2 was put into a container with 160 parts of pure water, stirred and dissolved, and ammonia gas was blown into the primary solution. When reacting while blowing carbon dioxide gas into the solution, lithium carbonate precipitated. After blowing in calculated amounts of ammonia gas and carbon dioxide gas, the reaction was continued by heating and blowing in ammonia gas and carbon dioxide gas for one hour at 80C. After cooling the reaction solution, lithium carbonate was separated, washed with water, and dried to obtain high purity lithium carbonate. The yield was 65 parts, or 88%.

The amount of impurities contained was as shown in the following table.

In addition, the numerical values in the table represent the value of 0, and ND represents not detected.

Further, high purity lithium carbonate (1) and (2) were produced using lithium perchlorate obtained by the method of Example 1 and the method of Example 2, respectively.

Claims (1)

[Claims] High purity carbonic acid characterized by crystallizing and isolating it, recrystallizing it using water and/or an organic solvent, and then reacting the crystals with carbon dioxide in a solvent under ammoniacal basicity. Lithium production method.