JP3031564B2 - Method for producing calcium carbonate using fluidized firing furnace - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing calcium carbonate using a fluidized sintering furnace, and more particularly, to a method for producing calcium carbonate with improved quality and stable quality.

(Prior art)

Calcium carbonate produced by injecting carbon dioxide gas into lime milk (hereinafter, simply referred to as calcium carbonate) has a particle diameter, dispersibility of particles, surface properties of particles, and the like, which are finely controlled in accordance with suitability for use. It has a wide range of industrial applications as a functional filler such as plastics, sealing agents, paints, paper, printing inks, adhesives and rubber.

As an essential process for producing calcium carbonate,
The first and important one is the firing of raw limestone. There are various types of limestone baking equipment such as Beckenbach furnace, Meltz furnace, rotary kiln, calcimatic furnace, etc.In the calcium carbonate manufacturing industry, almost vertical shaft kilns are conventionally used. However, only some rotary kilns can be seen. The reason for this is that the shaft kiln uses a solid fuel with high carbon content such as coke, which can be operated on a relatively small scale and has good thermal efficiency.
Normally 40-80mm rough stones are fired, so the size of the unfired material that is inevitably mixed is much larger than the calcium hydroxide (lime milk) particles obtained by hydrating the fired part. In other words, it is easy to remove an unfired portion by classification in a subsequent step.

By the way, a shaft kiln is operated by mixing approximately 10% of coke or coal into massive limestone and burning the solid fuel by ventilation from the lower part of the furnace. It usually takes two days to input raw materials from the furnace top and discharge quicklime from the furnace bottom, and it is difficult to take a completely continuous operating condition, and the operation is intermittent. For these reasons, the temperature range of the combustion zone is usually around 300 ° C (850
(~ 1150 ℃). Therefore, in quicklime obtained from a shaft kiln, the value of the activity, which is a measure of the reactivity of quicklime, greatly varies from 100 to 700 at a 100 g value. The concentration of carbon dioxide gas generated from the furnace top is not constant,
It swings in the range of%.

As for the activity of quicklime (890 is the theoretically highest value), calcium carbonate made from quicklime, which has high activity, has better dispersibility of particles and less residual alkali, so calcium carbonate is used for the final use. It has been empirically known that the compound is preferable when it is incorporated into another matrix. To obtain high activity quicklime, it is necessary to lower the firing temperature, but in order to complete the decomposition reaction of CaCO ₃ → CaO + CO ₂ , firing must be performed at about 900 ° C. or more. In the conventional vertical shaft kiln, it is difficult to control the temperature to a narrow width and the size of the rough stone is two factors. To keep the CaO acquisition rate economically acceptable, The set firing temperature has to be set higher, as a result of which some over-fired parts occur,
It is not possible to obtain quicklime which has a high activity and a small activity variation, which is preferable as a raw material for producing calcium carbonate.

On the other hand, recently, in the case of viscous fluids typified by sealing agents, paints, printing inks and the like, properties of calcium carbonate particularly strongly required include uniformity of viscosity and curing time of the viscous fluid in which calcium carbonate is blended. , And higher gloss when applied.
In addition, a neutralization reaction performed by blowing carbon dioxide gas into lime milk inevitably leaves a small amount of calcium hydroxide. For example, this alkali component deteriorates the hue of the vinyl chloride resin containing calcium carbonate, Improvement and stabilization are also issues.

[Problems to be solved by the invention]

In order to solve these technical problems with respect to calcium carbonate, as has been done conventionally, particles having a constant size are formed as much as possible in the step of carbonating lime milk, and the desired particles are dispersed in the subsequent step of dispersing the particles. Simply using calcium carbonate particles is inadequate, and as described above, the carbonation reaction using high activity and quick lime with extremely small variation in activity and carbon dioxide gas with a constant concentration. Is absolutely necessary.

For this purpose, a fluidized-bed kiln that can be completely continuously operated and automatically controlled has been attracting attention, in which limestone having a particle size of 5 mm or less is baked while floating and flowing in a hot air stream at a constant temperature.

However, the fluidized-bed firing furnace is disclosed in Japanese Utility Model Publication No. 63-1196.
As described in column 13 line to column 3 line 6, CaO + C
O ₂ → CaCO ₃ The reaction of calcium carbonate indicated by the reaction of CaCO ₃ , especially on the inner wall of the cyclone, caused the device to close in a short time, and on a commercial basis from the viewpoint of stable operation and continuous long-term operation Has been considered impossible.

The present inventors have conducted intensive studies on the improvement of the above-mentioned conventional fluidized-bed kiln, and as a result, by providing a calcining device (heat exchanger) between the collection cyclone directly connected to the kiln and the lowermost cyclone, the re-carbonation was performed. It has been found that the exhaust gas temperature can be controlled to a temperature lower than the reaction temperature, or that the recarbonation reaction can be controlled to a specific cyclone site to the utmost, so that stable operation of firing the powdery and granular material can be performed. 2-16 Ganping
9449).

Then, by reacting lime milk hydrated quicklime obtained by firing powdered and granular limestone in the fluidized-bed kiln and carbon dioxide gas generated from the furnace, high-quality, small-quality variation and stable It has been found that calcium carbonate having a high quality can be obtained, and that the above-mentioned demands for high physical properties in the art can be sufficiently satisfied, and the present invention has been completed.

That is, the present invention includes a suspension preheater configured by arranging a plurality of cyclones (C _{1 to} C _n ) in multiple stages above a firing furnace, and collecting cyclones of products directly connected to the firing furnace. Instead of the duct connecting (C) and the lowermost cyclone (C ₁ ), the powdered and particulate limestone is fired in a fluidized-bed kiln equipped with a preheating device provided with a fluidized bed or spouted bed type calcining device. A method for producing calcium carbonate, characterized by reacting lime milk obtained by hydrating quicklime and carbon dioxide generated from the furnace.

A fluidized-bed firing furnace used in the present invention will be described with reference to the drawings showing examples.

FIG. 1 shows a basic type of a fluidized-bed kiln using one calciner, and a partially cutaway front view of a main part, and FIG. 2 shows the furnace of FIG. 1 incorporated in a suspension preheater and a specific cyclone. Fig. 3 is a partially cutaway front view of an embodiment in which a plurality of calciners are used and the cyclone structure of the parallel plural type shown in Fig. 2 can be omitted. FIG. 4 is a partially cutaway front view of an embodiment in which an auxiliary combustion burner is added to the calcining apparatus.

First, FIGS. 1 and 2 will be described. The plurality of cyclones C ₁ , C _2a , C _2b , C ₃ , and C ₄ shown in FIG. 2 are arranged in multiple stages to form a suspension preheater (1). Limestone powder particulate material is introduced from the cyclone C ₃ and C ₄ and the raw material chute (3) provided in the duct (2) for connecting is preheated by exhaust gas from the fluidized bed sintering furnace (4), the preheating The powdered and granular raw materials are sequentially transferred to the firing furnace (4).
And fired. The product fired in the firing furnace (4) is cooled in a fluidized bed cooler (5) via a product collection cyclone C and the like, and is taken out and recovered from the conveyor (6) as a product.

Such present invention in apparatus, instead of the duct that connects the cyclone C ₁ lowermost constituting the collecting cyclone C and the suspension preheater (1), fluidized bed calcination apparatus (heat exchanger) (7) is arranged, and
The granular raw material preheated by the suspension preheater (1) is supplied and supplied. Incidentally, the exhaust gas flow at a flow rate of about 40 m / s discharged from the collection cyclone C is reduced to 2 to 5 m / s in the calcination device (7) and is preheated in the calcination device (7). The powdery and granular raw material undergoes a sufficient heat exchange by a stagnant flow for about 4 to 10 minutes, and is supplied to the above-mentioned firing furnace (4) through an L-valve (8). Further, the unfired powdery granular material in the calcining device (7) is directly collected by the collecting cyclone C for some reason.
In order to prevent it from being thrown into the
It is desirable that the duct (9) connected to the calcining device (7) has an elbow structure as shown in the figure. In the figure (10)
Is a pipe connecting the lower end of the calcining device (7) and the calcining furnace (4), and is used to pass unfired powdery and granular materials that fall from the calcining device (7) for any reason. ).

Next, describe its configuration while explaining the function for system diagram of FIG. 2, the suspension preheater (1) of the cyclone C ₁ -C ₄ constituting a re-carbonation reaction temperature range of 600 to 800 ° C. The generation of deposits under temperature conditions is specified for cyclones C _2a and C _2b having a switchable structure (see JP-A-2-63544).

That is, the conventional fluidized bed calciner is particulate material which is introduced supplied to the duct connecting the cyclone C ₁ of collecting cyclone C and the bottom is preheated to e.g. about 700 ° C., whereas,
Assuming that the temperature of the exhaust gas from the collecting cyclone C is about 1200 ° C., the heat exchange time in the duct is extremely short, so that the raw material temperature rises only to about 780 ° C. instead of being released from the cyclone C ₃ Exhaust gas temperature about 950 ℃
And very high. As a result, according to the prior art, cyclone
The exhaust gas temperature at C _2a and C _2b also increases accordingly,
Therefore, since the recarbonation reaction temperature is at the site of cyclone C ₃ higher than cyclones C _2a and C _2b , that is, the temperature range of 600 to 800 ° C., this cyclone C ₃ must also have a switchable parallel plural structure. Must.

On the other hand, according to the example shown in FIG. 2, the raw material at about 700 ° C. which has been charged into the calcining device (7) undergoes sufficient heat exchange in the calcining device (7), and the raw material temperature becomes For example, the temperature can be increased to about 820 ° C., and can be supplied to the baking furnace (4). The temperature of the exhaust gas from the cyclone C ₁ is also about 820 ° C., which is about 130 ° C. lower than that of the conventional baking furnace.
_2a , C _2b surely recarbonation reaction temperature range of 600 ~ 800 ℃
As a result, the recarbonation reaction site can be specified as cyclones C _2a and C _2b, and the occurrence of the recarbonation reaction phenomenon at other cyclone C ₃ and C ₄ sites can be suppressed.

The cyclones C _2a and C _2b are connected in parallel by valves (11a) and (11b), and by switching one of the valves (11a) and (11b), the other cyclone C _2a is operated while the other cyclone C _2a is operating.
It is configured to pause _2b . The above shoot (3)
Particulate material thrown supplied is collected is led from the duct (2) to the cyclone C _4, a common chute (12)
Through the branch chute (13), (14) through the duct (15),
Is supplied to the (16), it is collected by the cyclone C _3. Then, the raw material that has been collected by the cyclone C ₃ is charged from the chute (17) the duct (18), branch ducts (19), derived from the cyclone C _2a, the C _2b (20).

The raw materials collected by the cyclones C _2a and C _2b are supplied from the chutes (21) and (22) to the calcination device (7) via the chutes (23). The raw material charged into the calciner (7) is fluidized by the exhaust gas flow from the collection cyclone C for about 4 to 10 minutes as described above, and after sufficient heat exchange with the exhaust gas has been performed. Is supplied to the firing furnace (4) via the L valve (8). Further, sufficiently preheated calcined raw material guided to the cyclone C ₁ together with the exhaust gas stream is collected in the cyclone C _1, it is introduced into the calciner via a chute (24) (4).
In the firing furnace (4), raw materials are stored on a dispersion plate (25), and the raw materials are heated by a burner (26) and fired while being fluidized by air from a wind box (27). The fired product is guided from the chute (30) to the cooler (5) via the L valve (29) for performing material sealing from the chute (28).

Fine powder from the sintering furnace (4) is collected by the collecting cyclone C, a part of the fines is returned from the chute (31) to the sintering furnace (4), and the remainder is transferred from the chute (32) to the cooler (5). ). The cooler (5) is a dispersion plate (33)
Air is pressure-fed from a pushing fan (36) to two air chambers (35) partitioned by a partition plate (34). The air from the cooler (5) is
Air is supplied as combustion air from the duct (41) through the cyclones (39) and (40) from the ducts (7) and (38) to the wind box (27) of the firing furnace (4). The product collected by the cyclone (39) is guided from the chute (42) to the cooler (5), and the product collected by the cyclone (40) is supplied from the chute (43) to the cooler (5). ) With the product discharged through the chute (44).
1) A chute for supplying the product guided above to the cooler (5).

In the two cyclones C _2a and C _2b , a duct (19),
Exhaust gas containing particulate matter is supplied from (20), and the particulate matter is collected by cyclones C _2a and C _2b and shots (46), (4)
From 7), the exhaust gas is supplied to the calcining device (7) via the chutes (21) and (22), and the purified exhaust gas is discharged from the ducts (15) and (16). Shoot above (2
1) is branched to the chute (48) and the valves (50) and (51) are interposed, respectively, and the chute (22) is branched to the chute (49) and the valves (52) and (53) are interposed. I have. The ducts (15) and (16) are provided with valves (54) and (55). In the figure, (56) and (57) are pipes communicating with the atmosphere, (58) and (59) are atomizing means for supplying atomized water, and (60) and (61) are chutes (48). , (49) are containers for storing the deposits in the cyclones C _2a and C _2b flowing down from (49), (62) and (63) are crushers for deposits, and the crushed deposits are chutes (64) and ( It is led to the above-mentioned firing furnace (4) through 65). (66) is an exhaust gas fan.
The details of the means for removing the deposits formed on the cyclones C _2a and C _2b by the recarbonation reaction are described in detail in JP-A-2-6354.
The detailed description is omitted since it is described in Japanese Patent Publication No. 4

Next, the temperature characteristics in the cyclones C _2a and C _2b will be described. In place of the duct (2), a calcining device (heat exchanger) 7a is provided, and a normal temperature (about 20 ° C.) ℃), the raw material is preheated to about 350 ° C, and the temperature of the exhaust gas drops to about 350 ° C. Although not shown in the drawings, it is released to the atmosphere via an exhaust gas treatment facility. On the other hand, in the temperature characteristics of the conventional sintering furnace, a difference of about 150 ° C. was observed between the preheating temperature of the granular material and the exhaust gas temperature, indicating insufficient heat exchange.

Next, to describe the example shown in Figure 3, in this example, although not cyclone C _1, C ₂ only only shows a structure of the suspension preheater (1), cyclone C ₃ as FIG. 2, C ₄ may be provided in multiple stages. And this example, the basic example illustrated in Figure 1, the cyclone C ₁ and instead ducts connecting the cyclones C _2, fluidized or spouted bed type calcination apparatus (heat exchanger) (7a ). That is, two calciners (7) and (7a)
The re-carbonation reaction is generated in all cyclone parts of the suspension pre-heater (1) where the cyclones are arranged in a multi-stage manner.
It is a device that allows sufficient heat exchange so that a temperature range of ° C. does not occur. This example is different from the example of FIG. 1 in that the powdery and granular raw material at normal temperature is directly calcined by the above calciner (heat exchanger).
Or introducing supplied (7a), or, although not shown, the limestone powder particulate material was placed in the middle of the other cyclone C ₃ or C ₄ of the duct, the preheated particulate material in these cyclones Into a calcining device (heat exchanger) (7a).

For example, to describe the temperature characteristics in the case of this example, and is discharged from the cyclone C _1, the heat exchanged gas is supplied to the calcining device (heat exchanger) (7a), for example about 820 ° C., wherein the raw material The heat exchange is performed while the fluidized material is fluidized. During this fluidized heat exchange action is carried out for 4 to 10 minutes, the powdery and granular material charged at room temperature (about 20 ° C.) is about 450 minutes.
Pre-heated to ℃, and this calciner (heat exchanger)
The temperature of the exhaust gas supplied from (7a) to the next cyclone C ₂ also becomes about 450 ° C., and eventually the purified exhaust gas having a temperature of 450 ° C. or less is released to the atmosphere, and at the same time, the cyclone C ₂ The collected 450 ° C raw material is calcined (7)
820 where heat exchange was sufficiently performed.
As described above, the raw material at a temperature of ° C. is supplied to the firing furnace (4) via the L valve (8). Further, preheated to about 820 ° C. In the cyclone C _1, and is the collected raw materials through the chute (24) brought charged into the firing furnace (4). in this way,
According to this example, the temperature range of 600 to 800 ° C. at which the recarbonation reaction occurs cannot be obtained at any part of the cyclone constituting the suspension preheater (1), and thus the generation of deposits by the recarbonation reaction Therefore, the cyclones C _2a and C _2b have a parallel structure, and the means for alternately switching or alternately switching the cyclones C _2a and C _2b is not required at all, and the apparatus can be simplified.

Next, the example shown in FIG. 4 will be described. The calcining device (7) and / or the calcining device (heat exchanger) (7a)
An auxiliary burner (67) for preheating is provided in the raw material layer or in the free board portion. The auxiliary burner (67) is attached to preheat the powdery raw material in the calcining device (7) and / or (7a) to assist the start-up of the entire device. In the case of), re-carbonation of cyclone C ₁ at the time of start-up is prevented from occurring, and the heat load of the firing furnace (4) is reduced.
The size of the firing furnace (4) can be reduced. Further, when the operation is shifted from the start-up to the normal operation, the auxiliary heating by the auxiliary burner (67) may be stopped or the combustion may be intermittently performed.

Using quicklime obtained by calcining powdery and granular limestone in the fluidized calcining furnace as described above, hydrated lime milk is prepared by a conventional method, and the carbon dioxide gas generated in the calcining furnace is reacted with calcium milk to prepare calcium carbonate. Get. The activity of quicklime as a raw material is
The 100 g value is preferably 700 or more, and the variation in the activity is preferably 20 or less in standard deviation.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but these do not limit the present invention.

Examples 1 and 2, Comparative Example 1 A: Production of quicklime Limestone was fired using the fluidized-bed kiln shown in Fig. 2 and, for comparison, massive limestone was fired using a vertical shaft kiln. .

In both cases, the calcination time was two consecutive weeks, and the calcination temperature, limestone activity and carbon dioxide gas concentration were measured every two days, and the results are shown in Table 2. For each item, the average (A _ve .) And the variation (standard deviation σ) of the data of the six points obtained were calculated.

Prior to Table 2, the notes for use in Table 2 are described in Table 1.
It is listed in the table.

From the results shown in Table 2, it is apparent at first glance that in Examples 1 and 2, the sintering temperature was controlled extremely precisely. In addition, the uniformity (activity of quicklime and carbon dioxide concentration) of the two raw materials used in the carbonation reaction, in which carbon dioxide is blown into lime milk, which is a post-process, is also a comparative example obtained from a vertical shaft kiln. It turns out that it is far superior to 1. In particular, quicklime has an activity of 700 or more and a small variation (σ is 20
The following items cannot be obtained with conventional furnaces.

B: Production of Calcium Carbonate The quicklime obtained in Example 1, Example 2 and Comparative Example 1 was respectively poured into water to obtain lime milk having a specific gravity of 1.06, which was cooled to 17 ° C. Cooled lime milk was put into a 1 m ³ reaction tank, and carbon dioxide was blown from the bottom at 250 m ³ / hour to terminate the reaction.

The resulting calcium carbonate was left in a slurry state for 2 days under gentle stirring to disperse the calcium carbonate particles, and then a fatty acid soda was subjected to a surface treatment in an amount of 3% by weight based on the calcium carbonate. Dehydration, drying, and crushing were performed by a conventional method.

Application Example 1 A polysulfide sealing material was prepared using the surface-treated calcium carbonate obtained in Examples 1 and 2 and Comparative Example 1 as a sample, and the gelation time, which is the most requested physical property as a sealing material, was compared.

Formulation Substrate Polysulfide LP-32 Trade name, (manufactured by Toray Thiokol) 100 parts by weight BBP 20 Paraffin chloride 20 Stearic acid 1 Calcium carbonate (sample) 55 Hardener Lead dioxide 7.5 Chlorine paraffin 6.75 Stearic acid 0.75 After mixing well, knead with a planetarium mixer until no particles are observed, then leave in a constant temperature bath at 20 ° C, JIS A 5745
The time until gelation was measured in accordance with.

The sample number given to each sample is, for example, "Example 1-2" is the reaction of carbon dioxide from the fluidized-bed firing furnace of the present invention with lime milk obtained by hydrating quicklime in Example 1 on the second day. This indicates that calcium carbonate was produced by the reaction. For example, “Comparative Example 1-6” was obtained by reacting carbon dioxide from a vertical shaft kiln with lime milk obtained by hydrating quicklime on the sixth day of Comparative Example 1. To generate calcium carbonate. The same applies to the following application examples.

Application Example 2 A surface-treated calcium carbonate was obtained in the same manner as in Example 1 except that the surface treatment was performed with sodium rosin acid instead of the fatty acid soda, and a test for offset printing ink was performed using this as a sample. . The most required physical properties, the gloss of the printed surface formed on paper, were measured. The result is fourth displayed.

Formulation Super-glossy medium 70 parts by weight Calcium carbonate (sample) 30 Primary kneading Disper 600 rpm for 3 minutes Secondary kneading Three rolls once passing Ink coating Method Apply to a 25 x 25 cm art paper with an RI tester and air dry. The coating amount is in the range of 2.6~3.2g / m ^2.

Application Example 3 The number of days of storage in a slurry state under mild stirring was changed from 2 days to 1 day, and 3% by weight of fatty acid soda was changed to 1% by weight of sodium benzenesulfonate and 2.5% by weight of sodium rosinate per calcium carbonate. A surface-treated calcium carbonate was obtained in the same manner as in Example 1 except for performing the above procedure, and this was used as a sample and blended in an acrylic paint to compare the physical properties. The most required physical properties, the dispersibility of the particles in the paint and the gloss of the coated surface were measured. The results are shown in Table 5.

Mix Millbase Vinegar Bee Acrylic resin 8.7 parts by weight Thinner 20.8 Titanium white 20.9 Calcium carbonate (sample) 10.2 Put the millbase together with the same amount of glass beads in a mayonnaise bottle, disperse with Red Devil Mill for 45 minutes, and then 39.4 parts by weight -Acrylic resin was added and stirred and mixed for 3 minutes to obtain a paint.

Application Example 4 The surface-treated calcium carbonate obtained in Examples 1 and 2 and Comparative Example 1 were used as samples, and these were kneaded into a vinyl chloride resin, and the most required physical properties, that is, the hue of the sheet were compared.

Formulation Vinyl chloride resin (= 1000) 100 parts by weight DOP 50 Tribase 3 Lead stearate 1 Calcium carbonate (sample) 50 Kneading Rolling at 165 ± 5 ° C for 6 minutes Sheeting Pressing at 170 ° C for 2 minutes after preheating at 20 ° C / 20 kg / cm ² And the hue of the obtained sheet was measured with a spectrophotometer. The required physical properties are high whiteness (large L value) and low redness (small a value).

As is clear from the results of Tables 3, 4, 5 and 6, it can be seen that the calcium carbonate produced according to the present invention has higher physical properties and more stable physical properties. .

[Action / Effect]

As described above, according to the present invention, calcium carbonate having high and stable physical properties is commercially and advantageously provided.

[Brief description of the drawings]

FIG. 1 shows a basic type of a fluidized-bed firing furnace using one calcining apparatus used in the present invention, and a partially cutaway front view of a main part, and FIG. 2 shows the furnace of FIG. 1 as a suspension preheater. FIG. 3 shows another example of the fluidized-bed firing furnace used in the present invention, in which a plurality of specific cyclones are arranged in parallel and a plurality of types are used. FIG. 4 is a partially cutaway front view of an example in which a plurality of parallel-type cyclone structures can be omitted. FIG. 4 shows still another example of a fluidized-bed firing furnace used in the present invention. It is a partially cutaway front view of the example provided. 1 ...... suspension preheater C ...... collecting cyclone _{C 1, C 2a, C 2b} , C 3 C 4 ...... cyclone 2 ...... duct 3 ...... raw material charging chutes 4 ...... fluidized bed calciner 5 ...... fluidized bed cooler 6 Conveyor 7, 7a Fluidized bed or spouted bed type calcining device (heat exchanger) 8 L valve 11a, 11b Valve 12 Chute 13, 14 Branch chute 15, 16 … Duct 17… Chute 18… Duct 19, 20… Branch duct 21, 22… Chute 23… Chute 24… Chute 67… Auxiliary burner

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ identification code FI F27B 15/00 F27B 15/00 (58) Field surveyed (Int.Cl. ⁷ , DB name) C01F 1/18

Claims (3)

(57) [Claims] A plurality of cyclones (C ₁ to C ₁ ) are provided above a firing furnace.
C _n ) is provided in multiple stages, and a suspension pre-heater is provided. The duct connects the product collection cyclone (C) directly connected to the firing furnace to the lowermost cyclone (C ₁ ). A lime milk hydrated quicklime obtained by firing powdered limestone in a fluidized-bed kiln equipped with a preheating device provided with a fluidized bed or spouted bed type calcining device, and carbon dioxide gas generated from the furnace. A method for producing calcium carbonate, characterized by reacting. 2. The method according to claim 1, wherein the activity of quicklime used as a raw material is 700 or more at a 100 g value. 3. The method according to claim 1, wherein the dispersion of the activity of 100 g of quicklime used as a raw material has a standard deviation of 20 or less.