JP2002331300A - Method for manufacturing lime cake granulated dry product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a lime cake granulated dry product having good granulation properties and yield and suitably used for fertilizer or the like by lowering the water content of a hydrated line cake generated in large quantities in a sugar manufacturing factory by a simple technique before granulating the lime cake. SOLUTION: A dry powder is added to the hydrated lime cake generated in the sugar manufacturing factory to lower the moisture content of the lime cake to adjust the same to 25-30 wt.%. The obtained moisture content adjusted lime cake is subjected to extrusion granulation using a screen with a die diameter of 2.0-4.0 mm and the granulated cake is dried at 80-200 deg.C after granulation to manufacture the dehydrated lime cake granulated dry product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a lime cake granulated and dried product using a hydrated lime cake which is produced in large quantities in a sugar factory, and more particularly, to a method for reducing the water content of a hydrated lime cake. A method for producing a dried lime cake granule suitable for fertilizer applications, which can maintain good granulation properties and yield in extrusion granulation by lowering it by a simple method and controlling it to a certain range. It is.

[0002]

2. Description of the Related Art In sugar beet sugar factories, beet leach juice is produced during the process of sugar beet sugar, which contains proteins and various amino acids as impurities. The impurities are added to beet leach juice by adding lime milk to carbonation. To be removed. The hydrated lime cake is a dehydrated product of calcium carbonate generated by adding lime milk and carbonating in this cleaning step.

The average primary particle diameter of the dehydrated product is as small as about 1 μm, and the average particle diameter of the aggregated secondary particles is about 10 μm. For this reason, water is entrapped in the voids between the primary particles, and as a result, 3
0% by weight (% represents weight%) or more of water remains. Moreover, this lime cake is generated from a sugar factory in Hokkaido in terms of dry weight, 160,000 tons annually, of which 16% is used as fertilizer in grasslands and upland fields. In fact, the remaining 84% have been landfilled because of difficulties in handling such waste.

On the other hand, sugar beet, which is a main raw material for sugar production, is a crop that prefers alkaline soil. Since chemical fertilizers are generally acidic, if they are heavily used, the soil gradually becomes acidic, making the soil unsuitable for sugar beet cultivation. Therefore, it is necessary to spray lime and tankar (fine calcium carbonate) to return the acidic soil to alkaline. Sprinkling a lime cake containing calcium carbonate as a main component as a substitute for the lime or tankal has been considered for some time.

As described above, even after dehydration, the lime cake usually contains more than 30% by weight of water and is in the form of cake or sludge, so that it is difficult to spray it evenly and evenly on the field. Therefore, various studies have been made on expanding the use of granulated hydrated lime cake. For example, there is a method of adding a fertilizer granulation accelerator selected from pulp wastewater concentrate, polyvinyl alcohol, and carboxymethyl cellulose to a lime cake disclosed in Japanese Patent Publication No. 54-39304 and spray-drying to solidify the surface of the soft disintegrating particles. .

There have also been proposals other than those mentioned above, such as a method of adjusting the pH of a concentrated solution of stefen wastewater in JP-B-59-38181 to a specific range and adding the resultant to a fertilizer to perform granulation. There is a method of adding a granulating agent containing a concentrated solution of stephen wastewater to a dehydrated (preferably 25% or less dehydrated) lime cake disclosed in Japanese Patent No. 49773, kneading, extruding, granulating and drying. Further, Japanese Unexamined Patent Publication No.
No. 90203 (Japanese Patent No. 3116024) discloses that a hydrated lime cake discharged from a sugar factory is 20 to 30%.
And a method of granulating the hydrated lime cake by sequentially performing an extrusion granulation step, a drying step, and, if necessary, a calcination step.

[0007] However, lime fertilizers obtained by granulating hydrous lime cake have so far hardly been used. The biggest reason is that the water-containing lime cake, which is the raw material, contains excessive moisture for granulation. For example, Japanese Patent Publication No. 2-49773 discloses that when waste is discharged from a sugar factory, about 50% by weight of water is contained.
Even if it is left in storage for 2 years and naturally evaporated, it is said to contain more than 35% of water. According to the proposal of this publication, the hydrated lime cake is desirably dehydrated to 25% or less as described above, but there is no specific disclosure about the dehydration means.

The water content of the water-containing lime cake discharged from the sugar factory used in the above-mentioned Japanese Patent Application Laid-Open No. 11-90203 is also set to 20 to 30%. There is no description as to what means the water content containing 35% or more of water was reduced by spontaneous evaporation as in the aforementioned Japanese Patent Publication No. 2-49773.

[0009] The applicant disclosed in Japanese Patent Application Laid-Open No. 11-90203 and Japanese Patent Publication No. 2-49773 are the same applicant, but both of them relate to the technology for producing a dried product of a water-containing lime cake. No means is disclosed for reducing the water content of a hydrated lime cake, which is the most important starting material.

The applicant of the present invention is a limestone maker, and the manufactured limestone is used in various industries using limestone, including iron making and cement production. Among them are applications for sugar beet production. Here, as described above, it is used for removing impurities in beet leachate formed in the manufacturing process, and as a result, a hydrated lime cake is generated and its effective use is desired. The applicant of the present invention, which is a limestone maker, cannot be indifferent about the measures for treating the hydrated lime cake generated in such circumstances.

[0011] Under such circumstances, the applicant of the present invention has started to study measures for treating the hydrated lime cake. First, when the water content of the water-containing lime cake discharged from the sugar beet sugar maker was investigated, it was found that the water content of the water-containing lime cake discharged from the sugar factory was 30% or more.

[0012] Next, the present applicant has recognized that the present invention is most important, and has investigated the technology for reducing the water content of interest, and it has been found that a filter press has recently been used. Although this filter press has improved dewatering performance, it has also been found that the water content of 30% is regarded as the limit of dewatering in normal operation. Furthermore, although it is not impossible to forcibly apply a load to this dehydrator to reduce the water content, judging from the performance, power consumption, operation efficiency, etc. of the device, inefficient operation or difficult conditions It turned out to be.

As described above, the water-containing lime cake contains an excessive amount of water for granulation, and cannot be easily adjusted to water suitable for granulation, and originally contains a large amount of water. Increased costs due to increased drying costs, the use of expensive binders such as water-soluble polymers, and the complicated production process greatly hinder the practical use of lime cake granules.

[0014]

In view of such circumstances, the present inventors have conducted intensive studies on what method should be used to easily obtain a practically usable lime cake granulated product. In particular, the method of adjusting the water content was studied.
As a result, while maintaining good granulation properties and yield, a granulated and dried product having a certain range of particle size and strength required efficiently was obtained at low cost, and the present invention was reached.

[0015] That is, an object of the present invention is to provide a lime cake granulated product by simply and accurately reducing the water content of a water-containing lime cake, thereby providing a granulated product of lime cake. Another object of the present invention is to provide a method for producing a granulated and dried lime cake having a particle size and strength that can maintain the yield and can be used for fertilizers and the like.

[0016]

Means for Solving the Problems The present invention solves the above-mentioned problems, and for that purpose, in the method for producing a dried and dried granulated lime cake of the present invention, dry powder is added to a hydrated lime cake generated in a sugar factory. To reduce the water content,
The moisture content of the lime cake was adjusted in the range of 25 to 30% by weight, and then the obtained moisture content adjusted lime cake was extruded and granulated using a screen having a die diameter of 2.0 to 4.0 mm to form a lime cake. It is characterized in that it is dried at a temperature of 80 to 200 ° C. after the granulation.

According to the present invention, the moisture content of the lime cake before granulation can be easily controlled within a certain range by a simple means of adding and mixing dry powder such as quicklime to the hydrated lime cake, In addition, by extruding and granulating using a screen having a limited range of die holes, it is possible to obtain a granulated and dried lime cake having the required particle size and strength in a simple process.

The lime cake granulated and dried product thus obtained can be used as an alkaline fertilizer for preventing acidification of soil when growing sugar beet, which is a main raw material for sugar production. From the viewpoint of effective use, the present invention is significant. Furthermore, as the dry powder used for adjusting the moisture content, a lime cake granulated dry product manufacturing process, in particular, a granulated product crushed powder generated in the drying process can also be used,
In that case, a particularly efficient method for producing a dried lime cake product is provided.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention and details thereof will be described, but the present invention is not limited thereto, but is specified by the description of the claims. Needless to say.

The hydrated lime cake generated in the sugar beet factory is used to remove impurities such as proteins and various amino acids in beet leachate formed in the process of sugar beet production.
It is a precipitate formed in the carbonation reaction between the lime milk added to the leachate and the carbon dioxide gas in the carbonation-saturated tank or water-containing substances in which water after dehydration treatment of the precipitate remains. The moisture content of the wet lime cake immediately after precipitation or immediately after dehydration is usually 30% or more, as described above. Therefore, it is difficult to handle in the form of cake or sludge, and it is extremely difficult to uniformly adjust moisture by natural drying or heat drying.

On the other hand, in the present invention, the water content is reduced by a simple method of adding a dry powder to the water-containing lime cake, and the water content suitable for extrusion granulation is 25 to 25%.
It was adjusted to a range of 30% by weight. As a result, the obtained moisture content adjusted lime cake was prepared with a die diameter of 2.0 to 2.0.
It is characterized by extrusion granulation using a 4.0 mm screen and drying at a temperature of 80 to 200 ° C. after granulation. Adjusting the water content to the optimum water content in this way allows the amount of dry powder to be added in advance and allows the water content to be adjusted very easily and uniformly in a short time. The optimal value of the moisture content at this time is because the properties of the hydrated lime cake differ somewhat depending on the factory, etc.
Fine adjustment should be made according to the conditions at the time of granulation.

In the present invention, as the dry powder used for controlling the water content of the hydrated lime cake, limes, magnesia, calcium carbonate powder and the like can be suitably used. Examples of the limes and magnesites include quick lime, slaked lime, dolomite, lightly fired dolomite which is obtained by firing dolomite, magnesium hydroxide, magnesite, and lightly fired magnesia which is obtained by firing these oxides. However, from the viewpoint of adjusting the water content, quicklime powder, lightly burned dolomite powder, and lightly burned magnesia powder, which react with water to form a hydrate, are most suitable.

As the calcium carbonate powder, a so-called tancal powder obtained by pulverizing limestone or a synthetic calcium carbonate powder can be used, but the dried lime cake powder has a feature that it has a water absorption equal to or higher than that of the synthetic calcium carbonate. Therefore, it can be said that it is practical to use lime cake dry powder generated and collected in the drying step and the like, particularly crushed powder generated in the drying step and the like in the dehydrated lime cake granulated and dried product manufacturing process. Besides these, clay minerals such as bentonite are also effective.

Although it is not always practical in view of the effect as a fertilizer and the abrasion of the screen during extrusion granulation, powder such as crushed stone powder, fly ash, and various slag pulverized materials may be used. In any case, the moisture is 25 ~
There is no particular limitation as long as it is adjusted to 30%. By adding an appropriate amount of these dry powders and sufficiently kneading, the water content in the water-containing cake is homogenized, and an appropriate water-containing state is obtained.

For the granulation after adjusting the water content, an extrusion granulation method which can granulate even if the water content is high as compared with rolling granulation, stirring granulation or compression granulation is suitable. In order to granulate by a method other than the extrusion granulation method, it is necessary to reduce the water content of the lime cake to 20% or less, which increases the amount of dry powder used, increases the efficiency of production, increases the cost due to energy consumption, and increases the There are many problems when considering the load. As described above, granulation is not impossible with an apparatus other than the extrusion granulator, but it is considered that it is practically difficult to put the granulated material into practical use.

Extrusion granulators include a screw type, a roll type, a blade type, a self-molding type and a ram type depending on the extrusion mechanism, and are not particularly limited. However, it is possible to obtain a granulated material having a stable shape and tight tightness. In this respect, the roll type is most suitable. For fertilizers, the die hole is suitably 2.0 to 4.0 mm, and the moisture content suitable for granulating within the die hole range is 25 to 30%.

At this time, if the die hole is smaller than 2.0 mm, the production amount per unit time is reduced, which is not efficient. In addition, since excessive pressure is applied to the granulated product and water is released, the granulated product after extrusion becomes a lump, and a desired granulated product cannot be obtained. In order to prevent such agglomeration, it is necessary to further reduce moisture. Conversely, increasing the diameter to more than 4.0 mm is not preferable from the viewpoint of not only lowering the drying efficiency in the subsequent drying step, but also spreading the lime fertilizer uniformly and evenly on the field. On the other hand, if it is large, it is difficult to apply an extrusion pressure, and a tightly-granulated material having a stable shape cannot be obtained, leading to a decrease in strength.

In the present invention, the die diameter is 2.0 to 4.0 mm.
The water content of the water-containing lime cake before granulation is 25 to 30% after water adjustment as described above.
And more preferably 26 to 2
9%. If it is less than 25%, the adhesion between the calcium carbonate particles is poor, and the extruded granules cannot maintain the shape and collapse. Conversely, if it exceeds 30%, the extruded granules adhere to each other with excessive moisture to form a lump, so that a granulated product having a desired particle size cannot be obtained. As described above, the water-containing lime cake usually contains water of 30% or more, which exceeds the optimum water content in extrusion granulation as it is, and the method of the present invention is effective.

Although the raw granulated product after extrusion granulation has a columnar shape, even if it is dried as it is, there is no problem in use as a lime fertilizer. However, when further fluidity is required, it is preferable to use a sizing machine to make the particles spherical. As the sizing machine, a bread type or a drum type sizing machine can be used. If a marmellaizer (manufactured by Fuji Paudal Co., Ltd.) is used, a spherical shape can be obtained efficiently.

The hydrated lime cake contains proteins and various amino acids as impurities, and contains several percent of organic matter as it is. Therefore, a binder is not necessarily required.
Addition of a binder such as lignin, corn starch, polyvinyl alcohol, carboxymethylcellulose or the like at the time of kneading does not interfere at all, and rather, it is preferable to add an appropriate amount in that a more stable strength can be obtained. However, the die hole is 2.0 to 4.0 mm and the moisture content needs to be adjusted to 25 to 30%, as described above.

Drying after extrusion granulation is not particularly limited, but in view of the fact that granules do not adhere to each other and drying efficiency,
Rotary dryers and fluid dryers are most suitable.
The temperature is preferably from 80 to 200 ° C. If the temperature is lower than 80 ° C., it takes a long time for drying and the operation efficiency is poor. On the other hand, 20
When the temperature exceeds 0 ° C., decomposition of contained organic substances starts,
The contained components change and phenomena such as alteration and coloring occur. The drying must be performed sufficiently until the water content becomes 7% or less, preferably 5% or less.

Due to the nature of the organic matter contained in the lime cake,
If the water content exceeds 7%, the crushing strength is sharply reduced, which causes powdering. According to the present invention, the water content of the water-containing lime cake serving as the main raw material can be adjusted relatively easily by adding and kneading dry powder, and as a result, while maintaining good granulation properties and yield, It is possible to efficiently obtain a granulated and dried product having a required range of particle size and strength.

The granulated and dried lime cake thus obtained can be used, for example, as an alkaline fertilizer for preventing soil acidification when cultivating sugar beet, which is a main raw material for sugar production, and can be used to effectively use by-products from sugar production plants. From the point of view, it has the feature of high industrial utility value. The dried lime cake powder crushed in the drying step or the like can be used for adjusting the water content, and by doing so, a granulated and dried product can be produced very efficiently.

[0035]

The present invention will now be described with reference to Examples and Comparative Examples.
This will be described more specifically. In the following examples, the yield was calculated by sieving 1 kg of the dried and dried granulated product through sieves having openings of 2 mm and 4 mm, and measuring the weight of the granulated material falling within the range of 2 to 4 mm. The crushing strength was measured using a Kiya hardness tester, and the dried product after extrusion granulation was 3 mm in diameter and 5 to 6 in length.
mm particles were selected and measured by applying pressure from the side of the cylinder.
As for the sized product, particles having a diameter of 3.0 ± 0.5 mm were selected and measured. The number of measurements was 50 for each sample.
Individual. The water content was measured with a Kett infrared moisture meter.
The weight loss at 5 ° C was defined as moisture.

Example 1 Calcium carbonate generated in the cleaning process of a sugar factory was dehydrated with a filter press.
% To 5.0 kg of a hydrated lime cake containing 2% water
200 g of quicklime powder of 200 mesh was added and kneaded in a kneader for 5 minutes to prepare a granulated raw material having a water content of 28.1%.

This raw material was extruded into a fine disk pelletizer as an extrusion granulator (PV-5 / 11-2, manufactured by Fuji Paudal Co., Ltd.).
00D type), using a screen having a die hole of 3 mm and a thickness of 6 mm. A part of this granulated product was added to a baked granulator while adding dry powder of lime cake.
The mixture was sized for a minute and spheroidized. The yield and crushing strength of the dried lime cake obtained by drying these granules at 105 ° C. for 24 hours were measured.

Example 2 As in Example 1, 6.0 g of a hydrated lime cake containing 31.1% of water, 120 g of a concentrated solution of wastewater of stephen having a solid content of 55% and -200 were added.
Add 200 g of quicklime powder of mesh
The raw materials before granulation were adjusted by kneading for minutes. The water content at this time was 28.4%.

This lime cake was prepared using a Fine Disc Pelletta (PV-5 / 11-200D, manufactured by Fuji Paudal).
Using a screen having a die hole of 3 mm and a thickness of 6 mm, granulation was performed. Separately, this granulated product was sized by a pan-type granulator for 10 minutes while adding dry powder of lime cake to form a spheroid. The yield and crush strength of the dried lime cake obtained by drying these granules at 105 ° C. for 24 hours were measured.

Example 3 The same as in Example 1 was added to 6.0 kg of a water-containing lime cake containing 31.1% of water, and 300 g of lightly fired dolomite powder was added and kneaded in a kneader for 5 minutes before granulation. Was prepared. The water content at this time is 28.0%
Met. This water content adjusted lime cake was prepared using Fine Disc Pelletta (PV-5 / 1, manufactured by Fuji Paudal).
1-200D type), and granulated using a screen having a die hole of 3 mm and a thickness of 6 mm. Separately, this granulated product was spheronized by adding a dry powder of a lime cake for 10 minutes using a pan-type granulator to form a spheroid. These granules are added to 10
The yield and crush strength of the granulated and dried lime cake obtained by drying at 5 ° C. for 24 hours were measured.

Example 4 As in Example 1, 5.0 kg of a hydrated lime cake containing 31.1% of water was added to -325.
500 g of mesh tanker powder was added and kneaded with a kneader for 5 minutes to prepare a raw material before granulation. The water content at this time was 28.2%. This water content adjusted lime cake is fine disc peretta (Fuji Paudal,
PV-5 / 11-200D type), die hole 3mm,
Granulation was performed using a screen having a thickness of 6 mm. A part of the granulated product was spheroidized by adding a dry powder of a lime cake for 10 minutes using a pan-type granulator. The yield and crush strength of the dried lime cake obtained by drying these granules at 105 ° C. for 24 hours were measured.

Example 5 800 g of lime cake dry powder was added to 6.0 kg of a hydrated lime cake containing 31.1% of water as in Example 1 to obtain a granulated raw material having a water content of 27.2%. Prepared. This water content adjusted lime cake was disc-pelleted (F-5S / 11, manufactured by Fuji Paudal Co., Ltd.).
-175D type), using a screen having a die hole of 3 mm and a thickness of 12 mm. In addition, a part of the granulated product is a marmellaizer (QJ-400 manufactured by Fuji Paudal Co., Ltd.).
The mixture was sized with a residence time of 55 seconds while adding dry powder of a lime cake using a mold) to form spheroids. These granules are added to 105
The yield and crushing strength of the granulated and dried lime cake obtained by drying at 24 ° C. for 24 hours were measured.

Example 6 To 6.0 kg of a hydrated lime cake containing 31.1% of water as in Example 1, 120 g of a concentrated solution of wastewater of stephen having a solid content of 55% and 800 g of lime cake dry powder were added. A granulated raw material having a water content of 27.9% was prepared. This water content adjusted lime cake was disc-pelleted (F-5S / 11, manufactured by Fuji Paudal Co., Ltd.).
-175D type), using a screen having a die hole of 3 mm and a thickness of 12 mm. In addition, a part of the granulated product is a marmelizer (QJ-400 manufactured by Fuji Paudal Co., Ltd.).
The mixture was sized with a residence time of 55 seconds while adding dry powder of a lime cake using a mold) to form spheroids. These granules are added to 105
The yield and crushing strength of the granulated and dried lime cake obtained by drying at 24 ° C. for 24 hours were measured.

Example 7 200 g of quicklime powder was added and kneaded for 5 minutes while kneading 6.7 kg of a hydrated lime cake containing 31.1% of water as in Example 1 before kneading. Was prepared. At this time, the water content was 29.3.
%Met. This water content adjusted lime cake was prepared using a disk peretta (F-5S / 11-1 manufactured by Fuji Paudal).
75D, using a screen having a die hole of 3 mm and a thickness of 6 mm. A part of the granulated product was sized with a residence time of 55 seconds while adding a dry powder of a lime cake with a marmellaizer to form a spheroid. The yield and crush strength of the dried lime cake obtained by drying these granules at 105 ° C. for 24 hours were measured.

Example 8 Calcium carbonate generated in the cleaning process of a sugar factory was dehydrated with a filter press.
% Lime cake was added to 10 kg of lime cake, and 300 g of quicklime powder was repeatedly added and kneaded for 5 minutes in a kneader to prepare a total of 200 kg of a granulated raw material. The water content at that time was 29.5%. This water content adjusted lime cake was disc-pelleted (Fuji Paudal, F-
(Type 40) using a screen having a die hole of 3 mm and a thickness of 10 mm.

At this time, when the disk pelleter was observed, near the exit, a little adhesion and stagnation of the granules were observed, indicating that the water content was somewhat too high. Therefore, when the screen was replaced with one with a thickness of 5 mm and granulated again,
Good granules could be obtained. Screen thickness is 5m
m at the inlet temperature of 120 with a fluid bed dryer.
After drying at 50 ° C. for 50 minutes and measuring the water content, it was 1.5%. Further, the yield and crushing strength of the obtained dried granulated lime cake were measured.

Example 9 The same process as in Example 8 was repeated except that 800 g of dried lime cake powder was added to 10 kg of a hydrated lime cake containing 32.0% water, and kneading was repeated for 5 minutes in a kneader. Was prepared in a total of 200 kg. The water content at this time was 29.4%. The lime cake with the adjusted water content was granulated with a disk pelletizer (F-40, manufactured by Fuji Paudal) using a screen having a die hole of 3 mm and a thickness of 5 mm.

At that time, when the disk pelleter was observed, it was found that the column-shaped lime cakes tended to adhere to each other near the exit to form a nodule, but granulation was possible. The granulated product was treated with a fluidized bed dryer at an inlet temperature of
After drying at 50 ° C. for 50 minutes and measuring the water content, it was 1.8%. Further, the yield and crushing strength of the obtained dried granulated lime cake were measured.

[Comparative Example 1] 31.1% used in Example 1
3.3 kg of hydrated lime cake containing water of the same type as Fine Disc Pelletta (Fuji Paudal, P
V-5 / 11-200D type), using a screen having a die hole of 3 mm and a thickness of 6 mm, the granulation was attempted.
Column-shaped lime cakes adhered to each other near the outlet of the fine disk peretti to form a nodule and could not be granulated.

[Comparative Example 2] Calcium carbonate generated in the cleaning process of a sugar factory was dehydrated with a filter press.
% Hydrated lime cake containing 5.0% water,
0.1 kg of 200 mesh quicklime powder was added and kneaded with a kneader for 5 minutes to prepare 5.1 kg of a lime cake containing 30.7% of water.

This lime cake was prepared using a fine disk peretta (PV-5 / 11-200D, manufactured by Fuji Paudal).
Attempt to granulate using a screen with a die hole of 3 mm and a thickness of 6 mm in the mold,), but the columnar lime cake granules extruded with a fine disk pelleter adhere to each other, and A granulated product having the same diameter could not be obtained.

Comparative Example 3 Calcium carbonate generated in the cleaning process of a sugar factory was dehydrated with a filter press.
% Of dried lime cake was added to 5.0 kg of lime cake containing 5.0% water and kneaded in a kneader for 5 minutes to prepare 6.7 kg of lime cake containing 23.7% water. . This lime cake is fine disc perretted (PV-5 / 11-, manufactured by Fuji Paudal).
Granulation was performed using a screen having a die hole of 3 mm and a thickness of 6 mm by using a 200D type), but many of them were broken and became powdery.

Separately, this granulated product was sized with a residence time of 55 seconds while adding a dry powder of a lime cake with a marmellaizer. The yield of the dried lime cake obtained by drying these at 105 ° C. for 24 hours was measured.
The yields were as low as 22.4% and 17.2%, and the shapes were irregular. The crushing strength was too low to be measured.

[Comparative Example 4]
5.2 kg of a lime cake containing 1% of water was prepared. After kneading the lime cake with a kneader for 5 minutes, fine disk peretta (Fuji Paudal, P
V-5 / 11-200D type), granulation was performed using a screen with a die hole of 1 mm and a thickness of 6 mm, but water emerged on the surface of the columnar lime cake, and the vicinity of the outlet of the fine disk pelleter As a result, the column-shaped lime cakes adhered to each other to form a nodule and could not be granulated well.

[Comparative Example 5]
5.2 kg of a lime cake containing 1% of water was prepared. After kneading the lime cake with a kneader for 5 minutes, fine disk peretta (Fuji Paudal, P
V-5 / 11-200D type), using a screen having a die hole of 5 mm and a thickness of 6 mm. A part of the granulated product was sized and spheroidized for 10 minutes by a bread granulator without adding dry powder. These granules are added to 10
Of the granulated and dried lime cake obtained by drying at 5 ° C. for 24 hours, the crushing strength of 3.0 ± 0.5 mm particles among the sized granules was measured, but the measurement was too low. There are many particles that cannot be measured.
g.

Table 1 summarizes the physical property evaluation results of the dried granulated products obtained in the above Examples and Comparative Examples. From this table,
In the example, the yield of the granulated and dried product is as follows, except for the example 4.
It can be seen that in each case the 90% level is maintained. In Example 4, the yield was also in the 70% range, and the yield was far superior to that of the comparative example. Also, it can be seen that the crushing strength of the example is much better than that of the comparative example.

[0057]

[Table 1]

[Relationship between Crush Strength and Moisture] The dried lime cake granules produced in Example 9 were allowed to stand for 2 days in environments having different relative humidity, and the results of measurement of the moisture and crush strength are shown in Table 2. Show. This table shows that the lower the water content, the higher the crushing strength. It can also be seen that when the content exceeds 7%, the sudden crushing strength decreases.

[0059]

[Table 2]

[Differential Thermogravimetric Analysis of Granulated and Dry Product] The differential thermogravimetric analysis of the granulated and dried lime cake obtained in Example 5 was carried out.
The test was performed using TAS-100 manufactured by Rigaku Corporation. As a result, a large exothermic peak accompanied by weight loss appeared from 200 to 350 ° C. This peak is considered to be a combustion reaction of the organic matter contained in the lime cake, and the reaction changes the contained components and causes phenomena such as deterioration and coloring. Therefore, the drying temperature was set to 200 ° C. or lower.

[0061]

According to the present invention, the moisture content of the lime cake before granulation can be easily controlled to a certain range by adding and kneading dry powder such as quicklime to the hydrated lime cake. By extruding and granulating using a screen having a range of die holes, it is possible to obtain a dried lime cake having the required particle size and strength in a simple process. The lime cake granulated and dried product thus obtained is
When cultivating sugar beet, which is a main raw material for sugar production, it can be used as an alkaline fertilizer to prevent acidification of soil. The significance of the present invention is also significant from the viewpoint of effective use of products generated from a sugar factory.

Continuing on the front page (72) Inventor Shigeru Kasuya 8-1, Hirai-machi Hiraicho, Nishitama-gun, Tokyo, Japan Iron Mining Co., Ltd. (72) Inventor Kohei Sanko 8-1, Hirai-machi, Hinodecho, Nishitama-gun, Tokyo 1-day Iron Mining Co., Ltd. F-term (reference) 4D059 AA30 BD12 BD15 BF15 BJ01 BJ17 CC01 DA03 DA04 DA08 EB06 EB07 4G004 LA01 LA09 4G076 AA16 AB26 BA43 BA47 CA02 DA30 4H061 AA02 CC04 CC07 CC20 GG18 GG19 LL02 LL13 LL26

Claims (5)

[Claims] 1. A method for reducing the water content by adding dry powder to a water-containing lime cake generated in a sugar factory, adjusting the water content of the lime cake in the range of 25 to 30% by weight, and then obtaining the obtained water. 1. Die diameter of lime cake with content adjustment
A method for producing a granulated and dried dehydrated lime cake, comprising extruding and granulating using a screen of 0 to 4.0 mm, and drying the granulated product at a temperature of 80 to 200 ° C after granulation. 2. The method for producing a granulated and dried lime cake according to claim 1, wherein the dried powder is a powder of lime, magnesia or calcium carbonate. 3. The method for producing a granulated and dried lime cake according to claim 2, wherein the lime powder is quicklime powder. 4. The method for producing a granulated and dried lime cake according to claim 2, wherein the powder of magnesia is a powder of lightly fired dolomite or lightly fired magnesia. 5. The method according to claim 2, wherein the calcium carbonate powder is a dried lime cake powder.