JPS5983930A - Preparation of lithium carbonate - Google Patents

Abstract

PURPOSE:To prepare high-purity Li2CO3 having large primary particle size, by the thermal reaction of an alkaline aqueous solution of a lithium compound with urea. CONSTITUTION:Urea is added to an alkaline aqueous solution of a lithium compound (e.g. an aqueous solution of LiOH), the mixed solution is hydrolyzed with heat, and the precipitated Li2CO3 is filtered with suction and dried to obtain Li2CO3 having large primary particle size. The conventional process comprising the direct reaction of an aqueous solution of an Li compound with CO2 gas, a bicarbonate and a carbonate, is liable to cause the rapid local ununiform reaction, and the nucleation is dominant in the precipitation of the Li2CO3, resulting in the insufficient crystal growth, the generation of fine particles, the tendency of forming secondary particles by the coagulation of the fine particles, and the tendency to entrap the impurities from the mother liquid. A desirable result can be achieved by feeding the carbonate ion into the reaction system by the hydrolysis of urea, and a high-purity product having large primary particle size can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing lithium carbonate. The present invention relates to a method for producing lithium carbonate from an aqueous alkaline lithium solution. Lithium carbonate is used in medicine, optical glasses, electronic materials, etc. For example, in the field of electronic materials, it is used as a single-crystal material or an additive, but in this case, lithium carbonate is used as a pure material. Lithium carbonate is required. Conventional methods for producing lithium carbonate include 1, for example, a method in which carbon dioxide gas is blown into an aqueous solution of water-based lithium, or a solution made of an alkaline neutral lithium salt solution, and a method in which a bicarbonate compound or a carbonate compound is added to the solution. A known method is to precipitate IJ tium carbonate directly or by making it into an aqueous solution and adding vinegar to it. Since these methods directly react by adding carbon dioxide gas, a hydrogen carbonate compound, or a carbonate compound to an aqueous solution of a lithium compound, localized rapid heterogeneous reactions tend to occur. As a result, the lithium carbonate that precipitates becomes a system in which nucleation is the main activity and crystal growth hardly occurs, so the lithium carbonate becomes finely granular.
These have the disadvantage that they tend to aggregate to form secondary particles, and at that time, they incorporate impurities that exist in the world, resulting in a decrease in purity.

The present inventors have conducted extensive research to eliminate the drawbacks of the conventional method as described above, and to find a method for producing lithium carbonate that is commercially acceptable and has large particles, and has investigated the cause of the formation of fine particles in the conventional method. However, it is thought that this is due to the local reaction between lithium ions and carbon ions, i.e., the precipitation of charcoal (41 lithium) in a heterogeneous reaction system. As a result of various studies, the present invention was completed based on the discovery that supplying carbonate imen to the reaction system using urea hydrolysis WIVc brings about suitable results.The following 1
The present invention will be described in detail.

The alkaline lithium aqueous solution used in the method of the present invention is an aqueous lithium hydroxide solution, or an aqueous solution of a lithium salt such as lithium acetate, lithium benzoate, lithium chloride, lithium nitrate, or lithium sulfate, which is made alkaline with N@OH or the like. Among them, a lithium hydroxide aqueous solution is preferred.

In addition, since the bath expulsion of produced carbon L1-lithium increases rapidly below pH 9, the pH of the solution increases.
It is preferable to use H by adjusting it to be higher than D. Although there is no limit to the lithium concentration in the solution, it is preferable to keep it as high as possible for the purpose of conducting the reaction efficiently. The present invention tomako realistic stium aqueous solution (hereinafter referred to as
Add urea to the lithium aqueous solution in the fist.

Heating is carried out from the trap. At least an equivalent amount of urea is used per 9 parts of lithium. Note that since CO2 produced by hydrolysis exits the system as dregs, it is preferable to use more than I. When adding urea, even if you heat the lithium water bath solution and then add urea,
After urea is added to the lithium water bath solution at room temperature F, the mixed decomposition reaction can proceed, and the reaction can be carried out homogeneously, resulting in good results. The heating temperature is 60°C, preferably 7°C, which is the temperature at which the hydrolysis reaction proceeds.
Temperatures between 0 and 0°C are employed. The reaction can be stopped by discontinuing heating. Further, prior to the reaction, lithium carbonate having a solubility of f8 or higher can be made to exist in the lithium aqueous solution as a seed crystal.

In this way, lithium carbonate crystals with a length of about 20 to iooμ can be easily obtained. Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless the gist thereof is exceeded.

Example 1 Lithium hydroxide aqueous solution (
Two concentrations of yy-/1)too- were added, then urea in an amount equivalent to lithium was added, and the solution was dissolved at 1W. The liquor mixture was heated to qsc and hydrolysis was carried out for approximately S hours + vl. The pi (pi) of the solution was 1.27. The precipitated lithium carbonate was separated by suction filtration, dried at 110C, and then photographed.
It was observed that the length was 13θ~60μ) at ~20μ.6 The precipitation rate of lithium carbonate (J lithium hydroxide) was 30%.

Comparative Example 1 Urine 5? t7)') Vc NH,ytco3water rN (all: 7 o f-/l) 7θml was continuously added to the lithium hydroxide aqueous solution over a period of 5 hours to precipitate JR lithium oxide. Crystals of lithium oxide were precipitated, and the precipitation rate was 5. The crystals were scaly with a length of about 1Sμ.

[Brief explanation of the drawing]

Figure 2 is a scanning electron micrograph (y110x) of lithium carbonate obtained in Example 1 of the present invention, and Figure 2 is an electron decay pattern of lithium carbonate obtained in Comparative Example 1 of the present invention. I'm a sharpshooter (300x). Procedure 11 Full Circle (Method) March 8, 1980 Commissioner of the Japan Patent Office Kazuo Wakasugi Indication of the case 1982 Patent Application No. 8'F February 19266 Name of the invention Amending the manufacturing method of carbonated rib rum Applicant (59[3) Mitsubishi Chemical Industries, Ltd. Agent 〒10
0 Chiyo, Tokyo] - 11-ku Marunouchi Nigome 5-2 Mitsubishi Chemical Industries, Ltd. (1 other person) Date of amendment order (= J February 22, 1980 (shipment date) Subject of amendment Akira m A simple two-line explanation of the drawing in the book reads “
``...Lidium'' is next, followed by J3's ゛゛to Crystal I! "We accept li construction," he said. More than 195

Claims (1)

[Claims] (1) A method for producing lithium carbonate, which is characterized by subjecting an aqueous alkaline lithium solution to a heating reaction with urea.