JPS59146943A - Manufacture of manganese carbonate with high packing density - Google Patents

Abstract

PURPOSE:To obtain Mn carbonate with high packing density by crystallizing Mn carbonate from an aqueous soln. of a water-soluble Mn salt and an aqueous soln. of ammonium or alkali carbonate in the presence of Mn carbonate seed crystals while specifying the concn. of a reactive liq. CONSTITUTION:An aqueous soln. of a water-soluble Mn salt and an aqueous soln. of ammonium carbonate are added to different positions in a reactor in which a reactive slurry kept at about 10-90 deg.C and about 6.7-8.0pH is being stirred without directly mixing the solns. with each other, and a reaction is caused. Said reactive agents and a liq. contg. seed crystals are fed so that the residence time of them is adjusted to about 1-24hr, and the slurry is drawn from the reactor so as to keep the surface of the slurry in the reactor at a uniform height. The drawn slurry is separated into solid and liq., and part of the solid is returned to the reactor as seed crystals so as to keep the concn. of the slurry in the reactor at 300-1,200g/l uniform concn. as a whole.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing manganese carbonate precipitate from a soluble manganese salt aqueous solution and an ammonia or alkali carbonate aqueous solution. This invention relates to an improved method for precipitating.

Electrolytic manganese dioxide is usually used as manganese dioxide for batteries, but so-called chemical manganese dioxide, which is chemically synthesized without electrolysis, such as manganese dioxide obtained by firing manganese carbonate, is also used in some cases. ing.

Manganese dioxide for batteries is required to have as high a packing density as possible, but in order to obtain chemical manganese dioxide with such a high packing density, it is necessary to use manganese carbonate with a correspondingly high packing density as a raw material. However, no method has yet been found to industrially obtain manganese carbonate that meets these conditions.

For example, the method of U.S. Pat. No. 3,011,867 relates to a continuous precipitation method of mankan carbonate by thermal decomposition of an ammoniacal liquid of mankanan-ammonio complex containing manganese carbonate. It is said that it is possible to obtain manganese carbonate with uniformity and high bulk density, but the bulk density of manganese carbonate shown in the example is about 1.40, and the density of manganese dioxide obtained from this is The bulk density is 1.22 and the packing density is 1.6 to 1.7, which is significantly lower than the filling density of the currently commonly used electrolytic manganese dioxide, which has a packing density of 2.3.

A method for obtaining manganese carbonate with high bulk density by simultaneously adding equal amounts of manganese sulfate and alkali carbonate is also mentioned. For example, it is also described in Japanese Unexamined Patent Publication No. 57-200229. However, 4σ to 90°C, which is the invention in that publication,
Although a relatively heavy manganese carbonate precipitate with a packing density of 2.3 was obtained in the method described above, the packing density was still insufficient to produce manganese dioxide of electrolytic manganese dioxide grade.

When producing precipitates of hydroxides, sulfates, and carbonates with good crystallinity and r-permeability from aqueous solutions of various heavy metal salts, both reactant solutions are simultaneously kept at a constant pH and temperature at which the precipitates are formed. The method of adding in proportions is as follows:
For example, U.S. Patent No. 3,356,452 and Japanese Patent Publication No. 56
This has already been mentioned in Japanese Patent No. 13481, etc., and is a commonly used operation when a system in which two types of reactant liquids are mixed to form a precipitate is continuously carried out.

In order to obtain manganese carbonate with a high packing density, which is a suitable raw material for manganese dioxide for batteries, from a soluble manganese salt aqueous solution and an ammonia or alkali carbonate aqueous solution, the present inventors have determined the temperature, pH value, reaction solution concentration, stirring power, We investigated and considered various conditions for a suitable combination of the presence of seed crystals and the addition rate of the reactant, and based on the fact that it is extremely preferable to use a large amount of manganese carbonate seed crystals, we also investigated the conditions such as stirring power, pH value, reaction solution concentration, etc. The present invention has been achieved based on all suitable combinations of implementation conditions.

The method of the present invention basically consists of an aqueous solution of a soluble mankan salt such as mankan sulfate, mankan nitric acid/mankan chloride, and an aqueous solution of ammonia or an alkali carbonate, such as an aqueous ammonium carbonate solution, a solution in which carbonic acid scum is absorbed by ammonia; This method is characterized in that seed crystals of manganese carbonate are made to exist in advance when precipitating manganese carbonate through a complete reaction with soda carbonate or potassium carbonate.

In a preferred embodiment, a manganese sulfate aqueous solution with a manganese concentration of 0.5 to 3.0 mol/l and ammonium carbonate 0.5
~8.0 mol/l ammoniacal ammonium carbonate aqueous solution''
lr: The reaction slurry is kept at a predetermined value between 10° and 90°C and pH between 6 and 7 and 8.0, and the liquids do not mix directly with each other in different parts of the reaction vessel under stirring. Both reactants and seed crystals are added in such a manner that the total residence time of the above-mentioned reactants and the repeated seed crystal solution is 1 to 24 hours, preferably 2 to 9 hours. supply the liquid,
The streaky mass-liquid is extracted from the reaction vessel and separated into solid and liquid so that the liquid level in the reaction vessel is balanced, and a part of the solid content is repeated into the reaction vessel as a seed crystal, and the total amount of liquid in the reaction vessel is The slurry concentration is preferably 300 to 12009/l, preferably 5
It is held constant at a predetermined value between 00 and 8009/It. Further, the residence time of the content liquid is a value calculated from the volume reduction of the reaction vessel and the supply rate of the total volume liquid supplied.

The highest values of apparent density and packing density of manganese carbonate conventionally obtained are 1,94. ! il' eyebrow and 2.30
．． ! il/i, but the manganese carbonate obtained by the method of the present invention has an apparent density and a packing density of 2.31.9//7 and 2.58 g/CI, respectively! It is significantly heavier than carbonated mankan obtained by conventional methods such as those described above. This difference in packing density is estimated to be due to the fineness of the crystals of the mankan carbonate precipitate, the spherical particle shape, the smoothness of the surface of each particle, and the mixing ratio of coarse particles and fine particles. These particle properties are achieved only in the presence of an unusually large number of seed crystals. That is, when a highly concentrated slurry is kept at one temperature under stirring, the precipitate particles collide with each other, the corners of which are removed and rounded, and at the same time, the surface is polished and the packing density is increased.

Precipitate formation from a solution tends to occur around the substance that becomes the nucleus, but the more places there are to form nuclei, that is, the more seed crystals there are, the slower the formation rate becomes, and the denser the precipitate crystals become. However, the longer the particles stay in the reaction tank, the more elution recrystallization progresses, and the easier it is to form a single crystal. Reasons include the fact that the particles become heavier due to mutual compressive force. Although it is not clear which factor was effective, the presence of seed crystal particles has a tremendous effect in producing manganese carbonate with a high packing density, and it is possible to obtain manganese carbonate with a high packing density that was not previously possible. It is what makes things possible.

It has also been found that the stirring force has a large effect on the packing density of the produced precipitate, and also on the particle size distribution of the precipitate. If the stirring force is too weak, the slurry will not be mixed sufficiently, and even if the slurry concentration is maintained within a predetermined range, the packing density will barely reach 2.3 p/i. By applying sufficient stirring power and maintaining the slurry concentration within a predetermined concentration range, a precipitate with a uniform packing density was obtained.

The method of the present invention can be carried out either batchwise or continuously, but it can also be carried out in series and continuously using a plurality of reaction vessels with different stirring powers in order to adjust the particle size distribution of the produced precipitate. is also possible.

When the method of the present invention is carried out batchwise, it is advantageous to vary the stirring intensity stepwise or continuously as the slurry concentration increases, in order to produce manganese carbonate with a high packing density. It has also been found that by changing the stirring intensity during the precipitate formation period, precipitates with different p particle size distributions can be obtained.

Furthermore, by mixing two or more types of precipitates made with varying degrees of stirring intensity,
It was found that a new precipitate was obtained having a packing density that was higher than the original packing density that each precipitate had.

As an embodiment of the method of the present invention, it is also possible to adjust the particle size distribution by mixing precipitates obtained from a plurality of reactors in order to improve the packing density.

These effects of the present invention will be explained more specifically by the following examples.

Example 1 Using a covered reaction vessel equipped with a stirrer and having dimensions of 4 oCrrL in diameter and 4oC11L in height, quartz injection heater 2 was used while stirring 601/A manganese carbonate slurry liquid 457.
It was heated with a book and maintained at a predetermined temperature as described below.

A manganese sulfate solution with a manganese concentration of 1209/l was continuously fed into the reaction vessel at a rate of 807 rLl/min and an ammonium carbonate solution at a rate of 170 mJ/fi. Both reactant solutions were added so as not to mix directly in the reaction vessel.

The pH value of the slurry was controlled within the range of 7.0 to 7.1 by manipulating the feed rate of the ammonium carbonate solution.

An industrial pH meter was inserted into the reaction vessel to enable continuous measurement of I)H values. On the other hand, the slurry was extracted at a speed of about 340 mA'10 through a discharge pipe installed at the bottom of the container, and a portion of the solids separated from the slurry liquid by decantation was heated at 1300 j;
The milled slurry was semi-continuously returned to the stirred slurry at approximately 8,707 d, 0 min) through a pipe passed through a lid.

The residence time of the feed is 2.2 hours. The composition of ammonium carbonate solution is determined from the analysis results (NH,) 2. ,, It was COB.

This experiment was carried out at a slurry temperature of 20.40.50.60.70.
The temperature was changed to 80°C.

The results obtained are shown in Table 1.

Table 1: At 20°C, the packing density was slightly lower, but at 40°C or higher, the packing density was 2.40 JΔ or more. Mn in supernatant
The concentration was also sufficiently low.

Example 2 An experiment was conducted in the same manner as in Example 1, using a manganese nitrate solution instead of the manganese sulfate solution.

The results obtained are shown in Table 2.

Table 2 Example 3 Using a reaction vessel with a diameter of 40crrL and a height of 40crrL equipped with a stirrer, first 401ml of tap water was charged, and while the stirrer was running fully, the temperature of the liquid was raised to 60°C using two quartz heaters. Then, the temperature inside the tank is controlled to be 60'C. Manganese concentration 120 using metering pump
An El/13 mankan sulfate aqueous solution is added continuously at a rate of 511/Hz, and an ammonium carbonate aqueous solution is added continuously at a rate of 1011/Hr so that the two reactant solutions do not mix directly. When the liquid in the tank is almost full, the slurry liquid'&
Remove the IOA and transfer to another container to settle the slurry. The supernatant liquid is discarded and the sedimented slurry is returned to the reaction tank.

While repeating this operation, the slurry concentration in the reaction tank becomes 12.
The test was carried out until it reached 00gA. The pH value in the reaction tank was controlled to be in the range of 7.0 to 7.2 by increasing or decreasing the supply rate of the ammonium carbonate aqueous solution.

In Experiment 1, the rotation speed of the stirrer was kept constant at 3207 pm; in Experiment 2, it was kept at 3 until the slurry concentration reached 3509/l.
20 rpm, then 340 until it reaches 550 jj/l
7pm.

380 rpm until slurry concentration is 5509/l or higher
The stirring intensity was gradually increased as the slurry concentration increased.

In Experiment 3, the speed was 320 rpm until the slurry concentration reached 400 fl/It, and 360 T when the slurry concentration was 4009711 or higher.
The stirring intensity was changed so that pm.

The obtained results are shown in FIG. 1 as a relationship between slurry concentration and packing density.

From Figure 1, Experiment 1 shows the results when the stirring intensity is weak, and the packing density is 2 at a slurry concentration of 1 zooE/13.
．． It was 30. In Experiments 2 and 3, the stirring intensity was changed stepwise as the slurry concentration increased. Packing density 2.55-2,58 at slurry concentration 1200gA
of heavy manganese carbonate was obtained. The stirring strength needs to be strong enough to mix the slurry sufficiently. Figure 2 shows an electron micrograph of the carbonated manquats obtained in Experiment 2 with a flat, smooth spherical packing density of 2.54,9/Tsukuda. Indicated. (1) has a magnification of 100x, and (2) has a magnification of 4
It is possible to obtain densely shaped spherical particles with a small surface area that is 00 times larger than that of Example 3. The slurry concentration of carbonated mankan obtained in experiments 1 to 3 is 7001! Samples were taken at the time of 11/11, and a sieving test was performed.

The results are shown in Table 3.

From Table 3, it was found that the particle size distribution of the precipitate produced could be changed by changing the stirring intensity.

In addition, the results of mixing the samples of Experiment 2 and Experiment 3 in a one-to-one ratio are shown in the bottom column of Table 3, and the packing density is more different than the unique packing density of each sample. It has been found that by mixing a group of particles with different particle size distributions, a new powder having a packing density higher than that of each powder individually can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the results obtained in Experiments 1 to 3 of Example 3 as a relationship between slurry concentration and packing density. FIG. 2 is a diagram showing an electron micrograph of carbonated mankan obtained in Experiment 2 of Example 3 of the present invention. (1) has a magnification of 100 times, and (2) has a magnification of 400 times. Patent applicant: Toho Zinc Co., Ltd.
Electric Vt1ll Ill 1
tlLllll l: tl+1゛・ri concentration t
yC+ 257- child, ′, 5 畢, 1ゞpa, ′ta ゝ; za, j・+i ′)

Claims (3)

[Claims] (1) When crystallizing a manganese carbonate precipitate from a soluble manganese salt aqueous solution and an ammonia or alkali carbonate aqueous solution, in the presence of manganese carbonate seed crystals in the reaction tank, the slurry concentration in the reaction tank is adjusted to 300 to 1200.
A method for producing manganese carbonate with a high packing density, characterized in that the concentration is maintained at a constant concentration of 9/A. (2) When crystallizing a mankan carbonate precipitate from a soluble manganese/moth/salt aqueous solution and an ammonia or alkali carbonate aqueous solution, in the presence of mankan carbonate seed crystals in the reaction tank, the slurry concentration in the reaction tank is reduced to 300%. ~1200
A method for producing carbonated mankan with a high packing density, characterized by maintaining the concentration at a constant concentration of g/l and adjusting the particle size of the precipitate by varying the stirring power of a reaction tank. (3) When crystallizing a manganese carbonate precipitate from a soluble mankan salt aqueous solution and an ammonia or alkali carbonate aqueous solution, using multiple reaction vessels with different stirring powers,
In each reaction tank, in the presence of manganese carbonate seed crystals, the slurry concentration in the reaction tank was adjusted to 300 to 1200 g.
A method for producing manganese carbonate with a high packing density, which comprises stirring while maintaining a constant value of /A', and adjusting the particle size by mixing a plurality of precipitates obtained.