JPS6054915A - Spherical basic magnesium carbonate and production thereof - Google Patents

Abstract

PURPOSE:To produce the titled salt having a narrow particle size distribution in the form of spheres or spheroid close thereto, by subjecting a water-soluble magnesium salt and an aqueous solution of Na2CO3 kept within specific ranges of reaction concentration, reaction temperature and reaction rate to synthetic reaction. CONSTITUTION:A water-soluble magnesium salt, e.g. MgCl2, is reacted with an aqueous solution of Na2CO3 to synthesize basic magnesium carbonate. In the process, the temperature of the reaction system is kept at 40-80 deg.C, and both are mixed under >=0.1 S/V conditions between S(l/min) addition rate of the salt and the reaction volume V(l) under agitation and then allowed to stand and matured in the mother liquor. According to the process, the titled salt having aggregated particles, formed by aggregating fine primary particles in which the form is spheres or spheroid having >=0.7 (b/a) when the major axis is assumed as (a) and the minor axis is assumed as (b), and having 5-60mu particle diameter of the aggregated particles, 0.4-0.7g/ml bulk density and 10-40m<2>/dg specific surface area is obtained. The resultant salt is effectively usable as fillers for synthetic resins, cosmetics and carriers for agricultural chemicals and medicines, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel spherical basic magnesium carbonate which can be effectively used as a filler for synthetic tung fat, cosmetics or agricultural medicines, and a method for producing the same.

Conventionally, spheroidizing various inorganic powders has improved various powder properties such as filling, dispersibility, abrasiveness, and fluidity by spheroidizing the powder, giving it desirable characteristics. It is being Among these spherical powders, known examples include spherical calcium carbonate (Japanese Unexamined Patent Application Publication No. 57-92
519. ! ;7-9ko52θ, 37-q2jtko/sS
! ;-qsbiq>, spherical calcium sulfite (%Kaishoj
t3-/ll/9. ! ;), spherical alkaline earth metal silicate #A (Nichika Shigen, 727 (/97b)), spherical calcium tungstate (Nichika U10%/!; 2S (/q7
1)) There is a gin.

The conventional method for producing basic magnesium carbonate has been to use an aqueous slurry of orthomagnesium carbonate crystals as an intermediate raw material, heat-ripen it at a temperature of 60 to θ°C for 1 to several hours, and then separate the resulting crystals to 119 to 750 g A common method is to dry and ripen it by heating it to ℃, and then convert it into thread-like magnesium carbonate according to the following equation.

Heating! ;(MgCO,-3H20)--14MgCO,-
Mg(OH)2-1IH20+C02+1OH20 For this purpose, the required magnesium carbonate crystals are (11 water-soluble magnesium salt (magnesium chloride powder tri a m
(21) Thermal decomposition of magnesium bicarbonate (Mg(HCO2)2) (3) Any reaction in which carbon dioxide gas is blown into magnesium hydroxide slurry ~ It is prepared by.

In the above-mentioned conventional method for producing basic magnesium carbonate, in order to obtain crystals of uniform size by maintaining uniformity in the reaction system, there is a step of precipitating orthomagnesium carbonate crystals, and this is heated and aged to make basic magnesium carbonate. In the process of converting magnesium carbonate, the inside of the reaction tank is kept in a constant state of shield stirring.

The geomagnesium carbonate obtained by such conventional methods consists of plate-like microcrystals and has a p1 density of 0.
It is a very bulky powder of 2 to 0.3 P/at, and its viscosity increases when it is in a solution, and when it is in the form of a cake, it becomes solid.
There was a problem in that it would cause coalescence and would have to be crushed in order to be made into a product.

In addition, basic magnesium carbonate has a large amount of water of crystallization and carbon dioxide gas, and is known to be useful as a filler for flame retardant synthetic resins. When filling a resin with basic magnesium carbonate, it is extremely difficult to uniformly disperse and fill the resin in large quantities due to the above-mentioned properties of basic magnesium carbonate.

As described above, basic magnesium carbonate particles can be formed into spherical shapes (r), but basic magnesium carbonate can be used not only as a single crystal but also as a primary particle. It is difficult to make it into a spherical shape, and in order to make it into a spherical shape, it is necessary to aggregate all of the fine primary particles and make it into a spherical shape.To do this, the crystal precipitation rate is as fast as possible, and the crystals have to conform to their original shape. However, in order to speed up the precipitation, the reaction temperature may be increased, or stirring may be stopped or stirred slowly to prevent the destruction of the nested powder particles. It is known that "spherical" aggregates can be obtained, but the "spherical shape" is a deliberate shape in which sword-shaped basic magnesium carbonate crystals are intertwined, but fruit-like and have an extremely wide particle size distribution. , is a mixture containing disaggregated needle-like crystals and glue-like amorphous lumps.

On the other hand, as a method for producing spherical basic magnesium carbonate, there is also a method of mechanically shaping it into a spherical shape using a binder without controlling the reaction conditions, but the intervention of the binder is due to the inherent chemical and physical properties of basic magnesium carbonate. I don't like it because I have to pay a lot of money.

As a result of intensive research to overcome the above-mentioned problems with conventional basic magnesium carbonate powder, the inventor of the present invention has discovered that orthomagnesium carbonate crystals as a tomb-like magnesium carbonate precursor have been precipitated. By specifying F & 1, spherical agglomerated particles can be obtained, and it was previously discovered that the size of the spherical agglomerated particles can be varied by controlling the uniformity within the reaction system during precipitation, and in the reaction solution 81, By carrying out the synthesis reaction while maintaining the reaction temperature and reaction rate within a specific range, spherical basic magnesium carbonate with a narrow particle size distribution and a spheroidal particle shape similar to that of a reed matata can always be obtained. In addition, the obtained spherical basic magnesium carbonate exhibits characteristics as f# sticky powder, such as a large bulk density despite having a large specific surface area, and extremely good fluidity. When one highly concentrated slurry is made, there is no significant increase in viscosity and a large amount can be filled into the synthetic resin, and it has excellent properties even with fillers, making it effective in various fields; f' ! The present invention was completed based on the finding that the present invention can be used for various purposes. Therefore, based on the present invention and such knowledge, the shape of aggregated particles formed by agglomeration of fine primary particles is spherical or spheroidal with b/-≧0.7, where −k<diameter is 81 and minor axis ib. If the particle size of the aggregated particles is 5 to 60 μm, υ%
It provides a porous spherical basic magnesium carbonate with a bulky surface, a degree of O, a degree of O, 7 r/epsilon, and a specific surface area of lO to Om'/f. Furthermore, as a typical method for producing the above-mentioned spherical basic magnesium carbonate, the present invention involves a reaction in which a water-soluble magnesium salt and an aqueous solution of sodium carbonate are reacted to synthesize basic magnesium carbonate, and the respective concentrations are /, ! r mo-e/J
3 or less, and keep the temperature of the reaction system at 'elIo-go℃,
Under stirring, the addition rate S()7mln) to the ground is the reaction volume V
(-e) S/V vs. Ic≧0. ! Mixed under the conditions of j2,
The present invention provides a method for producing spherical basic magnesium carbonate, which comprises ripening the product in a mother liquor for 2 hours or more in silence. The method for producing basic 1-point atomized magnesium of the present invention is not limited to the above-mentioned method.

What, reaction #4*v, l! at the pressure of the present invention! l:ij - It is the sum of the volume of the magnesium ground aqueous solution and the sodium carbonate aqueous solution.

Hereinafter, one detail of the present invention will be briefly explained.

The water-soluble magnesium salts of the present invention include enriched magnesium and magnesium (IIltate) water bath solutions, bittern, and the like.

There are no strict limits on the concentration of the water-soluble magnesium salt and sodium carbonate aqueous solution, but too dilute solutions will increase the processing liquid phase, making it uneconomical, and too concentrated solutions will make it difficult to ensure the uniformity of the reaction slurry. As a result, the basic magnesium carbonate that is finally obtained contains many agglomerated particles in which spherical bodies are linked together in a chain, resulting in bulky basic magnesium carbonate with a wide particle size distribution. Degree 0 @5- / , ,! ; mol) /-
e is preferably used.

The mixing ratio of the above magnesium salt aqueous solution and sodium carbonate aqueous solution is determined in order to increase the yield of Mg.
It is better to charge a slight excess of Ium, and the molar ratio C071-
/ Mf? The range from /, 0 to /, / is clever.

In order to precipitate the spherical basic magnesium carbonate of the present invention, the temperature of the reaction system is 1IO to gθ°C, preferably 3-0 to 7
While maintaining the temperature at 0°C and stirring, the ground addition rate s (,, e/
min) 'React to @-S/V≧0 for 槓v(swamp)
-ts preferably Ko≧S/V≧0, lK? −.

It is extremely 1i form to add it like this.

In this specification, the term "addition" refers to the addition of a water-soluble magnesium salt to an aqueous sodium carbonate solution, or the addition of a sodium carbonate aqueous solution to a water-soluble magnesium solution. However, the former mode is common.

When the temperature of the reaction system is 170°C or the ratio of the addition rate to the ground and the reaction volume is less than s7v or θ, l, relatively innocent acicular or columnar magnesium orthocarbonate with a width of l to 20 μm and a length of 70 to 100 μm is formed. Production 1 The fine primary particles referred to in the present invention are not aggregated into a spherical shape, and no conversion into spherical basic magnesium carbonate occurs. On the other hand, when the temperature of the reaction system is higher than gθ°C, basic magnesium carbonate crystals form in the form of fine platelets similar to conventional basic magnesium carbonate. Further, there is no particular restriction on the upper limit of the S/V ratio, but S/V≧0. / is preferable, and in order to make the S / V ratio 2 or more, it is necessary to lower K once in the reaction solution, otherwise the viscosity of the slurry will increase rapidly [7, and it will be difficult to maintain the homogeneity of the reaction system] It becomes difficult.

The stirring intensity in the reaction system should be such that the precipitated magnesium orthocarbonate particles remain in a slurry state and the mixture and slurry concentration in the system are made uniform. results in the destruction of spherical agglomerated particles,
It is preferable because the shape of the basic magnesium carbonate finally obtained is changed from a flat disk shape to a conventional fine plate shape. The stirring time in the reaction system varies depending on the shape of the reaction vessel, the reaction volume, the shape and size of the stirring blade, and the stirring intensity, but it is preferable to keep it at the same time as the addition time to the ground or within 3 minutes after the completion of addition. Stirring for a longer period of time is undesirable because it prevents the fine primary particles that have precipitated from forming into spherical agglomerates due to dissolution precipitation during the static aging process.

Furthermore, in order to obtain the spherical basic magnesium carbonate of the present invention, a magnesium salt aqueous solution and a sodium carbonate aqueous solution are mixed under the above concentration, temperature, reaction rate, and stirring conditions, and then the precipitated fine particles are formed. It is essential to maintain the reaction temperature of the magnesium carbonate slurry at the time of mixing, and to statically mature the slurry in the liquid without stirring for a long time. In the conventional method for producing cyclic magnesium carbonate, d
l Keep the inside of the reaction system as homogeneous as possible, thereby increasing Mj+
In order to obtain basic magnesium carbonate with a large size, a mononormal magnesium carbonate slurry was converted and aged under stirring. In other words, it had no choice but to become a plate-like crystal. 17 The orthomagnesium carbonate slurry consisting of fine powder particles aggregates into a spherical shape by aging in the present invention, and gradually becomes spherical.
: Converted to magnesium carbonate. If the acid aging time is shorter than 1 hour, the conversion to spherical shape and the conversion of normal magnesium carbonate to basic magnesium carbonate will be incomplete, and even if the acid ripening time is longer than 7 hours, the conversion will not proceed any further.

In the present invention, in order to obtain spherical basic magnesium carbonate with a large average diameter, it is better to slow down the reaction reaction at a low temperature and shorten the stirring time after mixing; conversely, to obtain spherical basic magnesium carbonate with a small diameter. The conditions may be set to the opposite of these conditions, and by appropriately selecting each reaction condition, spherical basic magnesium carbonate having a desired average diameter can be produced.

The present invention provides a novel spherical basic magnesium carbonate structure that is clearly distinguishable from the structure of conventionally known basic magnesium carbonates.However, although the spherical basic magnesium carbonate has a large specific surface area, it has a low bulk density. Because it is large and spherical and has a narrow particle size distribution, it has excellent fluidity and dispersibility, and is useful as a filler for synthetic resins, cosmetics, agricultural medicines, etc. The spherical basic magnesium carbonate is also useful as a raw material for highly active magnesium oxide, which has unique powder characteristics.

Examples of the present invention will be described below.

Example/ 500 ml of magnesium chloride aqueous solution was added to SOθml of sodium carbonate aqueous solution at a rate of 2 ml/ml under stirring. At this time, the ratio S/V between the addition rate S (-13/mln) and the reaction volume V (shape) was 2.

Stirring was continued for 60 seconds after the addition began. After stirring 3
Matured for 1 hour at the same temperature [7 hours]. Then, the precipitate was filtered and cleaned and dried at 20° C. for S hours.

The reaction temperature at this time is 2,! Concentrated If ratio of sodium carbonate and magnesium chloride (No2Co3) / (Mg(J2) 1d, 0,
! ; , 210. ! 0 and θ, ri was 310.70.

The results of x#i1 diffraction of the dry product were all basic magnesium carbonate. The properties of the obtained cyclic magnesium carbonate are shown in Table 1, and micrographs showing the shape are shown in FIGS. 1 to 6.

If the reaction temperature is 170°C or lower, the spherical basic magnesium carbonate referred to in the present invention cannot be obtained, but at a temperature range of 4tθ°C to 70°C, a spherical one can be obtained.

When the reaction temperature exceeds gO 0 C, it becomes flat plate-like.

The optimum reaction temperature in this example is in the range of 0 to 70°C, but as the reaction temperature increases, the particle size of the spherical particles becomes smaller. Both particle size distributions are very narrow.

Dgf/, 0'l mo- held at 0°C at ψ11
/3 /-e sodium carbonate water #liquid S 00 mba
Pavement maintained at the same temperature under stirring/ , QQmoA/-13
Sooml of magnesium chloride aqueous solution at 24/m
It was added at a rate of ln.

The S/V ratio at this time was .

After the addition started, stirring was continued for 60 seconds. After the stirring was completed, the mixture was left to mature at the same temperature for 1-q hours, and then the precipitate was filtered and washed, and dried at 720° C. for S hours.

X-ray diffraction analysis of the dried product revealed that all the solids were basic magnesium carbonate. The properties of the obtained powder are shown in Table 2, and micrographs showing the shape are shown in Figs. 70 to 1 and 2.

Special opening 8GO-54915 (7) If the static aging time is 7 hours, basic magnesium carbonate aggregated into spherical shapes will not be obtained, but only irregular aggregates of fine primary particles will be obtained. When aged, basic magnesium carbonate aggregated into spherical shapes is obtained by dissolving and precipitating fine primary particles. However, there is almost no difference when left standing for 9 hours or more.

Example 3 Aqueous sodium carbonate solution with a concentration of 0073 man/J/2. ! ; and heated to 60°C. To this, 6θ
# degree 0.7mQI3/, 13 magnesium chloride aqueous solution/2,! ;-ek20-e/m1n(
Added at rate D. The SLV ratio at this time was 09g.

, Stir for 70 seconds from the start of addition, then stir at the same temperature for 3
It was left to mature for a while. Precipitates are removed after tPi overwashing/20°C
It was dried for S hours.

The obtained powder was confirmed to be cyclic magnesium carbonate by X-ray diffraction. Cml3, which was found to be spherical in scanning electron micrograph).

In Example 1, the sih ratio CNa2cOs:l/
[MgcJ2]=0.7310. ri01 reaction degree 6
0℃, addition rate of magnesium chloride aqueous solution,! i 0
ml/ml n and/00 yui/ml
n, stirring was stopped at the same time as the addition of vinegar was completed, and the mixture was left to mature at the same temperature for 3 hours. At this time, the S/V ratio ho, os and 0.
/Met.

The obtained powder was confirmed to be basic magnesium carbonate by X-ray diffraction. Its shape is determined by scanning electron microscopy: S/V=0.0! ; Then, it is flat plate-like (Fig. 1)
, S/V=0.7, it was spherical (Fig. 1S).

Example S Properties of the spherical basic magnesium carbonate obtained in Example/-4 as a powder (bulk density, angle of repose, specific surface area) and properties as a slurry (20% by weight of cyclic basic magnesium carbonate The viscosity of the aqueous slurry) was compared with that of conventional basic magnesium carbonate.

The bulk density was measured in accordance with JIS 6220, d111, and the angle of repose was measured using a powder tester (Prepared Powder Technology Research Center), and the specific surface area d was measured using a rapid surface area measurement device (BET/
The average particle size was measured using a Cirrus particle size distribution meter (laser light transmission method, Seishin Enterprises) K. The viscosity of the slurry was measured at 25°C with a Type B rotational viscosity of 18'11''.

The results are shown in Table 1IK.

Spherical basic magnesium carbonate has a bulk density 2 to 3 times higher than conventional products, and can be filled to a size of 1 as a filler for synthetic resins, and has a large specific surface S despite its large electric ratio II. It exhibits a value of 10 to Qm'/f/ depending on the particle size without decreasing, and is useful as a carrier for certain agricultural and medical products, and when it is made into a slurry, its viscosity is reduced by U7.

East Example B (Application example) Magnesium carbonate having a tangy shape as shown in FIG. The viscosity of the product was measured using a B-type rotary viscometer. For comparison, similar force measurements were conducted using conventional basic magnesium carbonate available on the market.

The results are shown in Table S.

The spherical fibrous magnesium carbonate of the present invention can be used as a filler for polymethyl methacrylate resin in a much more multi-image filling capacity than conventional #A-based magnesium carbonate.

[Brief explanation of drawings]

Figures 1 to 6 (Na2CoM) / [Mg(J2
) =0,! ;210. Figures 7 to 9 in j50
Figure [Na2Co,] / [MgR1,] = 0-
FIG. 3 is a micrograph showing all the effects of reaction temperature in Example 91/ in Example 310, 70. Figure 870 - Figures 1 and 2 are (Na2cos) / [Mg
(J,) = 1.0 Da//, 00 is a microscopic photograph of Example 1 showing the influence of standing aging time. FIG. 13 shows Example 3 (D, 1'IImF:J:S/V=0, O3s ml!i) at S/V ratio=o, g. This is a + Jr. micro-photograph of 1. Figure 1 is a microscopic photograph showing the entire engraving of conventional carbon-based carbon-resistant magnesium.
ilr/jrθ0 times, Figure 76 ti 3! ;Other than 00x, all are 330x. (J H++, R Tatsuhishiki Company Eagle 13 Figure 15 Figure 14 Figure 16 Figure 11 Mi Continuation 1'f, 'rlmi order →'' Showa 51 (year fl 7129 F+ Mr. Kazuo Wakasugi, Commissioner of the Japan Patent Office, 1. Indication of the case, Patent Application No. 15F1073 of 1982, 2. Title of the invention: Spherical basic magnesium carbonate and its manufacturing method 3. Person in charge Patent applicant 11 Location III 1-1-4 Mikage-cho, Toku 111, LI Prefecture
, Weight of the amendment order Voluntary 5, Number of inventions to be increased by the amendment 1] 6, "Detailed explanation of the invention" column 7 of the specification subject to amendment W, Contents of the amendment (1) Specification 1, page 3 '5(MgC(lx -311&(+)-1→IIM
g(If, -Mg(1111), -411,0+ J
r 5(MgCOl -31L O)-→4HzCG
, ・Mg(O1+), -4112(l+). (2) On page 3, line 14, "In the method, the inside of the reaction system...
" should be corrected to "In the method, the inside of the reaction system is...". (3) As an r-type IN manufacturing method on page 7, line 4, the present invention...'' is an r-type manufacturing method, and the present invention...''
Correct to. (4) Delete 1 from page 7, lines 13 to 14, "The basic magnesium carbonate of the present invention...is not limited." (5) Delete 1 from page 9, line 9 of the same. [Ratio of reaction volumes SR or 0.1
If “Reaction?” 'l! [If the product ratio S/V is 0.1 or less]]. (6) p. 13, line 6 r [NoLCO yo]/[Hg
Cl]' to r [Na, co, ]/[MgCL
] Corrected to J. (7) On page 13, line 10, "The properties of ... are also shown in Table 1.
`` is corrected to show the properties of r~ in Table 1 and ``. (8) "Sphericity (%)" in Table 1 on page 14 is corrected to "Sphericity (b/a) J. Procedural amendment September 30, 1981 Kazuo Wakasugi, Commissioner of the Patent Office 1. Indication of the case 1982 Patent Review No. 159073 2. Title of the invention Spherical basic magnesicum carbonate and its manufacturing method 3. Person making the amendment Relationship to the case Patent applicant address 1, Mikage-cho, Tokuyama City, Yamaguchi Prefecture No. 1 No. 4, Date of amendment order Proprietor 5, Number of inventions increased by amendment None 6, “Detailed description of the invention” column 7 of the specification subject to amendment, Contents of amendment (1) Article I ;(Page 4 line 1-1 110 units r 5(MgCO, -3112(1)-14M*C1
1,-Mg(Oll), -411,0+ J as “5(
卜18CO,・3112fl) Island 4hC+1.・h
(fill)t ・Correct to 411.41 + J. ″r one-prior IT, -iT et al. one-value t ()j:i':
) Dec. 12, 1980 Director General of the Japan Patent Office Kazu Wakasugi Daigan 1, Indication of Case Patent Application No. 159073/1982 2, Title of Invention Spherical Basic Magnesilano Carbonate and Process for Producing the Same 3, Person Making Amendment Case and Relationship Patent Applicant Zip Code 745 Address 1-1 Mikage-cho, Tokuyama City, Prefecture 1 Shipping Port November 1982 290 6. Subject of Amendment Column 6 for Brief Explanation of Drawings, Contents of Amendment (1) ) Page 23 of the specification f] Line 11 "Example 1 showed the influence of the reaction wet layer" is corrected to "Example 10 particle structure 1, which showed the influence of reaction temperature." (2) Paragraph 23 of the specification t'j I Line 3 and U 1 (Insert ri1''!child structure' in front of Line 3, line 11, ``Mirror photograph of rvI.'' (3) Line 19, page 23, 11 of the same, ``Does not indicate shape.'' is corrected to "r particle - does not show structure". I-1-zl"Itodera*ichi+l"i"tl' January 4-11, 1933 Manabu Shiga, Commissioner of the Japan Patent Office 1, Incident Title of the invention (1, J.) Magnesium carbonate, and its manufacturing method; (1111-) Relationship with h 1'; Single person address for patent purposes 1-1-5 Mikage-cho, Toku I11-shi, Il1kuchi prefecture, Supplementary 1
Number of inventions increased by 1 None 6, "i'!+ri request ftfl'i of supplementary zl elephant specification 111"
lul, +, “Detailed Description of the Invention 1 and “Fig.
Brief description of tr Contents of Column 1, 7, Supplement 11- (1) Specification Box 10 [The statement in Patent Claim fri lIl+, 1 is revised as shown in the attached sheet j1-1. (2) Specification No. 7 Line 11 11 ``Delete 11 for more than 2 hours.'' (:i) Specification box 1rvr: > Lines 1-1r' = Next to 1 in 1 liquid, ``Generally for more than 1114 hours'' is deleted. 11, especially add 1. (/l) statement box + + ct + /1 line 11 ``Xun'
i” I! ++li time is 1 “static thermal formation time j;
Although it cannot be determined unconditionally depending on the condition of Ift, it is generally 1 hour Iha 1, especially t 1 lti! Set R to old 1. (5) Specification No. = 2z (104th line 110) Add the following statement: "Example 7
/l mol/7if of carbonic acid I. , aqueous solution Fin (lit +?i/m
In speed τ addition 2-1 At the same time as the addition is completed, ifi'l'l' is set to 11-6,
Continue to let it mature for 1 hour. After filtering and washing the precipitate, it was dried at 120'C for 5 hours. As a result of X-ray diffraction, the dried product was spherical if, ≦basic magnesium carbonate. A water droplet is shown in the micrograph (Figure 17) showing the shape. 1 (6) Statement box 2 Add the following statement after the /+12th line. "Figure 17 is a micrograph (1000x) of the particle structure magnified by 1:1 in Example 7. (7) Add "Figure 17 1" in the appendix. Hereinafter, L 3 - Scope of Claims (+) When the shape of the fine -￥:lr- is formed by the book The spherical shape of 1.< is a spheroid, and the particle size of the aggregated particles is 5 to ri (171 m, the bulk density is 0./1 to 11.7 g/ml, and the specific surface area is 10 to 4
．． Spherical basic magnesilla carbonate with r1m2/g). 2) Water-soluble magnesilano, JIA and sodium carbonate,
I am familiar with the method of synthesizing basic magnesium carbonate by reacting an aqueous solution (I), and the reaction system is 1.5 degrees /In~8
The temperature was maintained at 0°C, and the stirring was carried out at the addition rate S (゛?i/m
1. A method for producing spherical basic magnesium carbonate, characterized in that 211 in) is further aged in mother liquor under conditions of S/V≧0°1 with respect to reaction volume V(?i). Senior 170 -85-

Claims (1)

[Claims] (When 11 fine primary particles are aggregated and the shape of the agglomerated particles has a major axis of 81 minor axis, b/a
≧0.7 spherical or spheroidal shape, the particle size of the aggregated particles is 3-10 μm, and the bulk density is 0.7 μm. lI~θ, 7
Spherical basic magnesium carbonate with a specific surface area of 70 to 70 m2/P. (2) In the method of synthesizing basic magnesium carbonate by reacting water-soluble magnesium with a sodium carbonate water bath solution, the temperature of the reaction thread is maintained at 170 to 0°C7,
While stirring, add salt '4#S (4/m1n) to reaction volume V (,, e) so that S/V≧0. 1. A method for producing spherical basic magnesium carbonate, which is characterized by mixing the mixture under the following conditions and skillfully aging it in a mother liquor for at least 1 hour.