JPH0838061A - Production of high-protein dried food from beer cake as stock - Google Patents

Abstract

PURPOSE:To economically obtain in high yield a good-quality high-protein dried food by using beer cake as stock. CONSTITUTION:This dried food is obtained by the following consecutive processes: beer cake with the water content adjusted to >=65wt.% is subjected to flaking crushing; water is added to the resultant crushed product into an aqueous slurry 3-5wt.% in solid concentration; the slurry is classified by using a 30 to 60-mesh sieve; the component passed through the sieve is left at rest; the resultant concentrated aqueous slurry containing 1-2wt.% of a high-protein material is dehydrated; and the resultant dehydrated product is subjected to such a high-speed drying process as to be brought into contact with hot air and kept at <=100 deg.C on average and brought to a moisture content of <=10wt.% within 60s.

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 dried product having a high protein content from beer lees as a raw material.

[0002]

2. Description of the Related Art In order to separate a high protein content contained in beer lees from beer lees, beer lees in a wet state are subjected to pressure crushing treatment, and the obtained pressure crushed products are treated in the presence of water. A method of sieving is known (Japanese Patent Publication No. 4-31666). This method does not include a chemical treatment step such as extracting beer lees with an alkaline aqueous solution under heating, and separates only high-protein contents contained in beer lees from physical treatments such as pressure pen treatment and sieving treatment. Since it is a method, it has an excellent advantage that high-quality and high-protein content can be separated and recovered in high yield.
However, some technical problems still remain in order to make this method industrially more advantageous. One of such problems is from a water slurry liquid containing a high protein content obtained after beer lees are pressed and sieved, the high protein content contained therein, without impairing its quality, It is a problem of how to separate and collect a high protein content from an aqueous slurry solution, which is how to separate and collect as a dried product in good yield and economically. In order to obtain a dried product with a high protein content, the aqueous slurry liquid containing the high protein content is subjected to solid-liquid separation as it is, and dried with an ordinary airflow dryer. In addition, there is a problem that a large device is required for the solid-liquid separation.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a dried product of high protein content from a beer lees as a raw material in good yield and economically.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, a pressure crushing step of pressure crushing beer lees having a water content adjusted to 65% by weight or more, and water is added to the obtained pressure crushed product to obtain a solid content concentration of 3 to
A water addition step of obtaining a 5 wt% water slurry solution, a classification step of classifying the water slurry solution using a 30-60 mesh sieve, and a standing step of allowing the sieve passing component obtained in this classification step to stand. And a dehydration step of dehydrating a concentrated water slurry liquid containing the high protein content obtained in this stationary step at a concentration of 1 to 2% by weight, and the obtained dehydration product is brought into contact with hot air to average the dehydration product. A method for producing a high protein content dried product using beer lees as a raw material, which comprises a high-speed drying step of maintaining a temperature at 100 ° C. or lower and obtaining a dried product having a water content of 10% by weight or less within 60 seconds. Provided.

Next, the present invention will be described with reference to the drawings.
FIG. 1 shows a process diagram for producing a dried product containing a high protein from beer lees as a raw material. In FIG. 1, 1 is a pressure crushing step, 2 is a water addition step, 3 is a first classification step, 4 is a water addition step, 5 is a second classification step, 6 is a standing step, 7 is a dehydration step, 8 is high speed drying. Step, 9 is a dehydration step,
10 is a combustion process, 11 is an exhaust heat recovery process, and 12 is a third classification process. Reference numeral 13 indicates a water tank.

In order to produce a dried product having a high protein content from beer lees according to the process diagram shown in FIG. 1, the beer lees are supplied from a line 21 to a pressure crushing step 1. Beer meal is a saccharification residue of beer malt (may contain rice, corn grits, corn starch, etc. as by-products) that is a by-product in the wort production process (preparation process) in beer production. Usually, beer lees are separated from wort in a solid-liquid separation device such as a filter tank or a wort filter in the preparation step with a water content of about 80% by weight.
It contains about 5% by weight of protein. In the present invention, beer meal having a water content of about 70 to 80% by weight separated from wort can be used as it is as a raw material. Also, dehydrate or dry beer lees once it has a water content of 6
It may be adjusted to 5% by weight or more and used as a raw material.

The pressure crushing step 1 is a step of crushing beer lees while giving a compressive force to the beer lees, whereby the protein-containing substance adhered to the husks is peeled from the husks. As the pressure crushing device, any crusher having a structure that gives a compressive force to the raw material to be treated can be used, but a roll mill is particularly preferable. In the pressure crushing process using a roll mill, the beer meal in a wet state is crushed by the compression force between the rolls, and by this pressure crushing process, germs and particles of high protein that are bound or adhered to the husks. Is peeled off and ground. The gap between the rolls is 0.05 to 2 mm, preferably 0.1 to
It is 0.3 mm. When the beer lees are pressed and crushed, the water content of the beer lees is sufficient if the water content is such that the husks are not finely pulverized, and may be 65% by weight or more. If the water content is too low, a part of the husk will be pulverized, and it will be difficult to screen the pressed crushed product into the husk and the protein-containing material.

The product obtained by pressing and crushing the beer lees obtained in the pressing and crushing process 1 (hereinafter, also referred to as the processed product (1)) is sent to a water adding process 2 through a line 22, where the processed product. Recycled water from lines 41 and 43 is added to (1) and stirred. The water addition step 2 is carried out using a stirring device, and in this case, any stirring device can be used as long as it can uniformly disperse the treated product (1) in water. However, those having a propeller stirring blade are generally used. The amount of water added to the treated product (1) is such that the solid content concentration is 3 to 5% by weight, preferably 4 to 5% by weight. The stirring time is not particularly limited, but generally 5 to 30 minutes, preferably 1
0 to 20 minutes. Further, this water addition step can be performed in two or more steps, if necessary.

Treated product (1) obtained in the water addition step 2
The water slurry liquid containing is sent to the first classification step 3 through the line 23, and the processed material (1) is classified therein. In the first classifying step 3, various sieving devices having a sieve can be used, but it is particularly preferable to carry out using a vibrating sieving device. As the vibrating and sieving device, any device such as a circle or a prism can be used.
Opening of sieve (wire mesh) is 30-60 mesh (0.2
It is about 13 to 0.567 mm). When classifying (sieving) the processed product (1) using a sieving device, the water slurry liquid containing the processed product (1) is supplied onto the sieve and passed through the sieve of the processed product (1). The obtained component is recovered as the first classified product (3A). The first classified product (3A) is obtained as an aqueous slurry liquid in which the high protein content is dispersed in water. In the first classification step, among the treated products (1) obtained in the pressure pen crushing step,
Coarse particles mainly composed of malt-derived husks were obtained as a sieve non-passing component [first classification treated product (3B)], and fine particles composed of high protein content peeled from the inner surface of the husks (protein content of 50 to 52). (% By weight) is a sieve-passing component [first
It is obtained as a classified product (3A). The first classified product (3A) made of the high protein content that has passed through the sieve obtained in the first classification process 3 is sent to the stationary process 6 through the line 31. On the other hand, the component on the sieve that does not pass through the sieve [the first classified product (3B)] is used in order to further separate and collect the high protein content contained in it.
It is sent to the watering step 4 through the line 24.

In the water addition step 4, recycled water from the line 44 is added to the first classified product (3B) obtained in the first classification step 3 and stirred. In this case, the amount of water added is such that the solid content is 3 to 5% by weight, preferably 4 to 5% by weight. This watering step 4 can be carried out in the same manner as in the case of the watering step 2.
The water slurry liquid containing the first classified material (3B) obtained in the water adding step 4 is sent to the second classifying step 5 through the line 25, where it is classified. This second classification step 5,
It can be carried out in the same manner as in the case of the first classification step 3. A sieve passing component consisting of the high protein content product obtained in the second classification step 5 [second classification treated product (4
A)] is sent to the stationary step 6 through the line 26, while the coarse particle component (second classified treated product (4B)) mainly containing husks that does not pass through the sieve is passed through the line 32 to the dehydration step. Sent to 9.

In the stationary step 6, fine particles containing a high protein content dispersed in water are precipitated and concentrated. This stationary step 6 is carried out by using an ordinary sedimentation separation tank having a liquid supply port at the top and a liquid discharge port at the bottom. The standing time is 5 minutes to 2 hours, preferably about 10 to 20 minutes.
In this stationary step 6, the high protein content precipitates with the passage of time, and a concentrated water slurry liquid containing the high protein content in a high concentration is formed in the lower part of the settling tank. The solid content concentration in this concentrated water slurry is 0.5 to 2
%, Preferably 1-2% by weight. In addition, in this stationary step 6, part of the fat (vegetable fats and oils) contained in the high protein content is eluted in water, which improves the protein content in the high protein content.

The concentrated water slurry liquid containing the high protein content at a high concentration settled in the stationary step 6 is separated from the upper aqueous phase (supernatant) of the concentrated water slurry water by withdrawing it from the bottom. To do. The separated concentrated water slurry liquid is sent to the dehydration step 7 through the line 27. On the other hand, the aqueous phase separated from the concentrated water slurry liquid is sent to the water storage tank 13 through the lines 31 and 39.

In the dehydration step 7, the concentrated water slurry liquid having a high protein content is dehydrated, and the water-containing high protein content is recovered as a dehydrated product. This dehydration step 7 includes a continuous centrifuge, a drum filter, a leaf filter,
It is carried out using a dehydrator such as a filter press. A preferred dehydrator is a continuous centrifuge. The water content of the high water content protein obtained in this dehydration step 7 is 80 to 90% by weight, preferably 80 to 85% by weight. This high water content protein is sent to the drying step 8 via line 28. On the other hand, the water obtained in the dehydration step 7 passes through the lines 38 and 39 to the water tank 13
Sent to

In the high-speed drying step 8, the dehydrated product (water-containing high protein content) obtained in the dehydration step 7 is dried to obtain a dried product of high protein content. When carrying out this high speed drying step 8, depending on the drying conditions,
It was found that the obtained dried product of a high protein content undergoes unfavorable alterations such that the color thereof becomes black, the appearance becomes poor, and the digestibility of pepsin decreases. In order to prevent such undesired alteration of the high protein content, the water-containing high protein content is contacted with hot air, and the average temperature of the water-containing high protein content is adjusted to 10
A dried product having a water content of 15% by weight or less, preferably 10 to 12% by weight, which is maintained at a temperature of 0 ° C or less, preferably 80 to 90 ° C, and under a short time condition of 60 seconds or less, usually 30 to 60 seconds. It is necessary to dry the water-containing high protein content so as to obtain Examples of the dryer for performing such high speed drying include a rotary kiln dryer, a drum dryer, a hot air dryer, and the like. The temperature of the hot air to be brought into contact with the high water content protein content is 300 to 500 ° C., preferably 400 to 450.
° C. Further, as the hot air, heated air is preferably used.

The high protein content dried product obtained in the high speed drying step 8 is recovered through a line 29.
Since this dried product usually contains lumps, if necessary,
This is crushed, adjusted to a desired particle size, further added with an antioxidant, filled in an appropriate container or bag, and then sold as a product. When adjusting the particle size of the high protein content, the particle size is 0.1-1.0 mm, preferably 0.4-0.5.
It is preferable to adjust the particle size so that it falls within the range of mm. Also,
This particle size adjustment can be performed using a crusher,
A roller mill or a high speed crusher is preferably used as the crusher in this case. Further, when adding an antioxidant to a high protein content, as the antioxidant, conventionally known additives legally approved, such as ethoxyquin for feed applications, if food applications Vitamin E or the like is used.

The second classification component (5B) (eg, husks) obtained in the second classification step 5 which does not pass through the sieve is line 3
It is sent to the dehydration step 9 through 2 and dehydrated. This step can be performed using a normal dehydrator, such as a screw press, a centrifuge, or a filtration device. The second classification component (5B) contains 85% by weight or more of water, usually about 91% by weight.
Although it contains water by weight, this water is dehydrated by this dehydration step to a water content of 75% by weight or less, usually 65 to 70% by weight. The dehydrated product obtained in the dehydration step 9 is sent to the combustion step 10 through the line 33. On the other hand, since the separated water obtained in this dehydration step 9 contains a small amount of unseparated solid matter, the line 35
And sent to the solids separation step 12.

In the solid matter separation step 12, the solid matter from the separated water obtained in the dehydration step 9 is separated. This solid matter separation step 12 is carried out using the same apparatus as in the stationary step 6 and using a normal sedimentation separation tank having a liquid supply port at the top and a liquid outlet at the bottom. The standing time is 5 minutes to 2 hours, preferably about 10 to 20 minutes. A concentrated water slurry liquid containing unrecovered proteins and other solids is formed in the lower part of the settling tank. The solid content concentration in the concentrated slurry liquid is 0.5 to 1.5% by weight, preferably 1.0 to
It is 1.5% by weight. The concentrated water slurry liquid containing unrecovered proteins and other solid substances settled in the solid matter separation step 12 is extracted from the lower part of the concentrated water slurry liquid so that the aqueous phase (supernatant) above the concentrated water slurry liquid is removed. To separate. The separated concentrated water slurry liquid is sent to the dehydration step 9 through the line 36. On the other hand, the aqueous phase separated from the concentrated water slurry liquid is sent to the water storage tank 13 through the lines 37 and 39.

In the burning step 10, the coarse particle-shaped solids mainly containing the husks obtained in the dehydrating step 9 are burned. The combustion process 10 is performed using various incinerators (combustion furnaces) such as a conventionally known fluidized bed incinerator and rotary incinerator. The hot combustion gas from the combustion process 10 is sent to the exhaust heat recovery process 11 through the line 34. In the exhaust heat recovery step 11, heat is recovered from the combustion gas, and as the heat recovery device in this case, various conventionally known devices can be used. For example, combustion gas and water or low temperature steam. Generally, an indirect heat exchanger for exchanging heat with a medium such as air is used. In the present invention, this exhaust heat recovery step 11 is preferably carried out so that heat is exchanged between the combustion gas and a gaseous substance such as air to obtain hot air. Then, the hot air thus obtained is the line 5
0 to be used as a heat source in the high speed drying step 8.

The water obtained in the standing step 6, the dehydration step 7 and the solids separation step 12 in the present invention is stored in a water storage tank 13 and is supplied from here to a pressure crushing step 1, a watering step 2 and a watering step 3. To be done. In addition, industrial water is supplied to the water storage tank 13 from the line 46 as needed.

The method of the present invention comprising the process diagram shown in FIG. 1 can be modified in various ways, for example, the second classification process 5 can be omitted. In this case, the sieve non-passing component (3
B) is sent to the dehydration step 9.

[0021]

Next, the present invention will be described in more detail with reference to examples. All% shown below are based on weight.

Example 1 Beer lees were treated according to the process chart shown in FIG. (Compression Pulverizing Step 1) 100 kg of beer meal (water content 78%, dry matter weight 22 kg) obtained in the filtering step of the raw material in the beer manufacturing step was subjected to pressure pulverizing treatment with a roll mill having a roll interval of 0.1 mm. (Water addition step 2) Compressed crushed product of beer lees obtained in compressed crushing step 1 (protein content based on dry matter 25.5
%) 100 kg and 447 liters of water were put in a tank, and the mixture was stirred and mixed by a propeller stirrer for 10 minutes. (First classification step 3) Aqueous slurry liquid containing the beer lees obtained in the water addition step 2 under pressure compression (solid content concentration 4%)
A 55 mesh sieve (wire mesh) (opening 0.250
mm) was used for classification, and 189 kg of a non-passing sieve component (water content 91%, dry matter weight 17 kg) consisting of coarse particles mainly composed of husks was collected on the sieve and a sieve passing component. As the above, 358 liters of an aqueous slurry liquid (solid content concentration 1.4%, dry matter weight 5 kg) containing a high protein content substance (protein content ratio 52%) was recovered.

(Water addition step 4) 189 kg of the non-passing sieve component obtained in the first classification step 3 and 236 liters of water were put in a tank and stirred and mixed for 10 minutes with a propeller type agitator. (Second classification step 5) The water slurry liquid (solid content concentration 4%) of the sieve non-passing component in the first classification step 3 obtained in the water addition step 4 was used in a vibrating sieve device equipped with a 55 mesh sieve. 167 kg of non-passing sieve component (water content 91%, dry matter weight 15 kg) is recovered by sieving, and an aqueous slurry liquid containing a high protein content (protein content rate 47%) as a sieve passing component (solid content concentration 1 %, Dry matter weight 2.0 kg) 258 liters were recovered. (Standing process 6) The first classification process 3 and the second classification process 5
A total amount of 616 liters of an aqueous slurry liquid containing each high protein content obtained as a sieving component was placed in a tank and allowed to stand for 10 minutes. By this standing, a concentrated water slurry liquid having a high protein content settles in the lower part of the tank.
It was separated and collected from. The amount of the concentrated water slurry liquid (solid content concentration 2%) of the high protein content obtained as a sediment by this standing was 370 liters, while the amount of the supernatant (solid content concentration 0.1%) was 246. It was liter. (Dehydration step 7) A high-speed centrifuge (3600G) is used for the water slurry liquid of the high protein content obtained in the stationary step 6.
Then, 38 kg of dehydrated product having a water content of 85% was obtained.

(Drying Step 8) The dehydrated product obtained in the dehydrating step 7 was dried by a rotary hot air dryer to obtain 6 kg of a dried product containing a high protein content having a water content of 10%. In this case, the hot air temperature was set to 440 ° C. The average temperature of the material to be dried during drying was 100 ° C. or lower, and the drying time was 60 seconds. (Particle size adjusting step, antioxidant adding step and filling step) The lump-shaped dried product obtained in the drying step 8 was crushed with a pin mill and sieved with a 30 mesh sieve to obtain 6 kg of a sieve passing component. Ethoxyquin as an antioxidant was added to this powder product at a ratio of 90 ppm, and the mixture was stirred and mixed by a mixer, then filled in a plastic bag and sealed. (Dehydration step 9) 167 kg of the non-passing component of the sieve obtained in the second classification step 5 mainly containing husks (water content 9
1%) was dehydrated by a screw press to obtain 50 kg of dehydrated product having a water content of 70%. (Combustion Process 10) The dehydrated product obtained in the dehydration process 9 was easily combusted when it was combusted with kerosene as a fuel in a rotary combustion furnace.

Reference Example 1 When the protein content of the high protein content in the precipitate obtained in the stationary step 6 was examined, the protein content was 52.5%. It was confirmed that the protein content ratio before the step was higher than 50.0%. This indicates that in this stationary step, part of the fat content in the high protein content was eluted in water, and the protein content in the high protein content was improved by that amount.

Reference Example 2 In the drying step 8, the high protein content containing water was dried under various conditions, and the color and shape of the obtained dried product were visually observed, and the dried product was digested with pepsin. The rate was measured as follows. The results are shown in Table 1.
Shown in (Measurement of pepsin digestibility) The method of measuring pepsin digestibility based on official standards is as follows. A sample is defatted in a 0.2% pepsin hydrochloric acid solution, put into it, digested under certain conditions, filtered, and then put on a filter paper It measures the crude protein content of indigestibles,
The pepsin digestibility is calculated by the following formula. Pepsin digestibility = (A−B) / A A: sample crude protein mass (%) B: sample undigested crude protein mass (%)

The pepsin digestibility means the ratio of the degradability of a protein digested with pepsin, which is one of the digestive enzymes, to the amount of crude protein. The higher the value, the better the quality of the protein. Indicates that.

[0028]

[Table 1]

The structure and drying method of the dryer shown in Table 1 are as follows. (Hot-air type agitating dryer) Drying method: A method in which raw materials are uniformly dispersed by a rotary blade while being fed into a hot air stream that rapidly flows in a drying tube, and are instantaneously efficiently dried and discharged.
The raw material is dispersed and powdered in the hot air stream, and drying progresses while being entrained, so the drying time is extremely short. (Drum dryer) Drying method: The raw material supplied is 2
It is formed into a film by being molded by a drum of a book, drying is completed in a short time while the drum makes one rotation, and the film is peeled off by a scraper. Drum surface temperature is 14 with steam
It is 0 to 150 ° C. (Nauta mixer) Drying method: In a batch type dryer, the supplied raw material is carried to the wall surface of the jacket by a screw that revolves around its axis, and the heat from the jacket raises the product temperature. The heated raw material moves all over the vessel by the rotation of the screw, and the heat necessary for evaporation of the moisture is given from the raw material, so that the raw material promotes the temperature drop at that time. (Airflow dryer) Drying method: A method in which the raw materials are uniformly distributed while being fed in parallel with the hot airflow that rapidly flows in the drying tube, and the material is instantaneously and efficiently dried and discharged. The raw material is dispersed and powdered in the hot air stream, and drying progresses while being entrained, so that the drying time is short. (Explosive combustion dryer) Drying method: Solid-liquid separation and drying are instantaneously performed by a pressure wave generated from a pulse engine to obtain a dried product. At the same time, the dried product is separated and recovered from the combustion gas, and the combustion gas absorbing water is released to the atmosphere.

[0030]

EFFECTS OF THE INVENTION According to the present invention, beer lees are used as a raw material, and from this, a high-quality, high-protein-containing material can be produced economically in a high yield. In the present invention, in particular, the product obtained by the pressure crushing step is subjected to classification treatment by adding water to the product to obtain a water slurry liquid having a solid content concentration of 3 to 5% by weight, which causes clogging of the sieve. And the classification operation can be performed easily. In addition, the water slurry liquid containing the high protein content obtained in this classification step, without directly supplying it to the dehydration step, once becomes a concentrated water slurry liquid containing a high protein content in a high concentration in the stationary step. Converting, supplying this concentrated water slurry liquid to the dehydration step, and dehydration, compared with the case of directly dehydrating the water slurry liquid of the high protein content obtained in the classification step, the water slurry liquid to the dehydrator There is an advantage that the supply amount is small and the scale of the dehydrator is downsized. Further, in the drying step of the water-containing high protein content product, hot air is brought into contact with the water-containing high protein content product, and the average temperature of the water-containing high protein content product is maintained at 100 ° C. or lower. Since it is dried at a high speed for 60 seconds or less, the obtained dried product has an excellent appearance, and its pepsin digestibility is high, and it is excellent not only as a sample of livestock and fish but also as a raw material for seasonings.

[Brief description of drawings]

FIG. 1 shows a process diagram for producing a dried product having a high protein content from beer lees according to the present invention.

[Explanation of symbols]

 1 Pressure Pen Milling Process 2 Water Addition Process 3 First Classification Process 4 Water Addition Process 5 Second Classification Process 6 Standing Process 7 Dehydration Process 8 High Speed Drying Process 9 Dehydration Process 10 Combustion Process 11 Exhaust Heat Recovery Process 12 Solids Separation Process 13 Water Storage Tank

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Nomura 2-12-1, Tsurumi Chuo, Tsurumi-ku, Yokohama-shi, Kanagawa Chiyoda Kakoh Construction Co., Ltd. Chome 12-1 Chiyoda Kako Construction Co., Ltd. (72) Inventor Takeshi Minami 2-12-1 Tsurumi Chuo, Tsurumi-ku, Yokohama-shi, Kanagawa Chiyoda Kako Construction Co., Ltd.

Claims (7)

[Claims] 1. A pressure crushing step of pressure crushing beer lees having a water content adjusted to 65% by weight or more, and water is added to the obtained pressure crushed product to obtain a water slurry having a solid content concentration of 3 to 5% by weight. A watering step for obtaining a liquid and this water slurry liquid for 30 to 60
A classification step of classifying using a sieve with a mesh opening, a static step of statically leaving the sieve passing component obtained in this classification step, and a high protein content obtained in this static step having a concentration of 1 to 1. The dehydration step of dehydrating the concentrated water slurry liquid containing 2% by weight, the dehydrated product obtained is brought into contact with hot air, the average temperature of the dehydrated product is kept at 100 ° C. or lower, and the water content is 10% by weight within 60 seconds. A method for producing a high protein content dry product using beer lees as a raw material, which comprises a high-speed drying step for obtaining the following dry product. 2. The method according to claim 1, wherein the sieve non-passing component obtained in the classification step is dehydrated in the dehydration step, and the dehydrated product obtained is burned. 3. The classifying step is carried out in two steps, water is added to the non-passing sieve component obtained in the first classifying step to prepare a water slurry solution having a solid content concentration of 3 to 5% by weight, which is then added. Second
The method according to claim 1, wherein classification is performed in the classification step, and the sieve-passing component obtained is supplied to the stationary step. 4. The method according to claim 3, wherein the sieve non-passing component obtained in the second classification step is dehydrated in the dehydration step, and the dehydrated product obtained is burned. 5. The method according to claim 1, wherein a vibrating screen device is used in the classifying step. 6. The method according to claim 1, wherein a centrifuge is used in the dehydration step. 7. The method according to claim 2, wherein the combustion exhaust gas obtained during the combustion is indirectly heat-exchanged with air, and the obtained heated air is introduced into the high-speed drying step.