JP5681447B2 - Method for producing regenerated particles and regenerated particles - Google Patents

Description

  The present invention relates to a method for producing regenerated particles using paper sludge as a raw material and regenerated particles.

  Various methods have been proposed for producing regenerated particles using papermaking sludge as a raw material. For example, a method of performing carbonization prior to combustion treatment of papermaking sludge (for example, Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4, etc.), a device used for combustion treatment, a method for specifying the combustion temperature, combustion time, etc. in detail (for example, see Patent Document 5, Patent Document 6, Patent Document 7, etc.), etc. Exists.

  In addition, there are proposals in which the main raw material for papermaking sludge is limited to deinking floss, as the origin (source) of the papermaking sludge as a raw material is an obstacle to stabilizing the quality (for example, patent literature) Refer to 8 etc.).

  Furthermore, paying attention to the problem of hardened and low whiteness of the regenerated particles obtained, the problem of thickening and solidifying when slurryed, a method for specifying the pulverization method in detail and blowing carbon dioxide (for example, patent document) 9), a method for specifying in detail how carbon dioxide is blown in (see, for example, Patent Document 10) and the like.

  However, the methods disclosed in Patent Documents 1 to 7 have a problem that the manufacturing method is complicated and it is difficult to stabilize the quality. Moreover, although the method disclosed in Patent Document 8 can stabilize the quality, there remains a problem that the manufacturing method is complicated. Furthermore, the methods disclosed in Patent Documents 9 and 10 are excellent in improving the problem of thickening and solidifying when slurried, but the problem remains that the manufacturing method is complicated.

Japanese Patent No. 4153411 Japanese Patent No. 3563707 JP 2002-308619 A JP 2010-194486 A Japanese Patent No. 3831719 JP-A-11-310732 JP 2008-207173 A JP 2008-127704 A JP 2002-356629 A JP 2009-292666 A

  The main problems to be solved by the present invention are hardened, low whiteness problems, regenerated particles in which the problems of thickening and solidifying when slurried are solved, and such regenerated particles are easily and stably produced. An object of the present invention is to provide a method for producing regenerated particles that can be obtained in a practical manner.

The present invention that has solved this problem is as follows.
[Invention of Claim 1]
A method for producing regenerated particles by dewatering and heat-treating paper sludge,
The main raw material of the papermaking sludge is deinked floss discharged in the newspaper wastepaper manufacturing process ,
The content ratio of calcium carbonate in the inorganic particles contained in the papermaking sludge exceeds 70% by mass.
A method for producing regenerated particles.

(Main effects)
When papermaking sludge is burned at a high temperature, a cementitious substance is generated from calcium carbonate and kaolin in the papermaking sludge. As a result, the obtained regenerated particles are hardened and have a low whiteness, and problems of thickening and solidification occur when slurried. However, the deinking floss (newspaper deinking floss) discharged in the newspaper wastepaper manufacturing process has the characteristics of relatively high calcium carbonate and relatively low kaolin. By using newspaper deinking floss, the amount of cementitious material produced is reduced, and the occurrence of the above problems is suppressed.
In addition, the present method only uses newspaper deinking floss as the main raw material for papermaking sludge, and does not require detailed control of combustion processing, etc., so that regenerated particles in which the above problems are solved can be obtained very easily. it can. Moreover, since the quality of newspaper deinking floss is more stable than that of mere deinking floss, it is possible to stably obtain regenerated particles in which the above problems have been solved.
Note that newspaper deinking floss has a calorific value enough to cause self-combustion due to the relatively low ash content of the newspaper used as a raw material and the fact that newspaper ink contains oils and fats and carbon black. Therefore, the amount of heat supplied during the combustion process can be minimized.

[Invention of Claim 2]
The heat treatment is divided into at least a drying process and a combustion process,
The combustion treatment is performed so that 80% by mass or more of calcium carbonate is decomposed into calcium oxide.
The method for producing regenerated particles according to claim 1.

[Invention of Claim 3]
The heat treatment is divided into at least a drying process and a combustion process,
The combustion treatment is performed at a combustion temperature of 750 to 900 ° C. and an oxygen concentration of 3 to 18%.
The method for producing regenerated particles according to claim 1 or 2.

(Main effects)
When calcium carbonate is decomposed into calcium oxide, it is combined with kaolin to produce anorthite (hard substance), and thus conventionally has a tendency to suppress decomposition of calcium carbonate (see, for example, Patent 4 above). Therefore, the combustion process has become extremely complicated. However, the present invention uses newspaper deinking floss as the main raw material of the papermaking sludge, so the ratio of kaolin is low and the formation of anorthite is suppressed. Therefore, it is not necessary to suppress the decomposition of calcium carbonate, and the combustion process can be simplified.

[Invention of Claim 4]
Slurry the combustion product after the heat treatment, and blow carbon dioxide into the slurry.
The manufacturing method of the reproduction | regeneration particle | grains of any one of Claims 1-3.

(Main effects)
When the combustion product after the heat treatment is slurried and carbon dioxide is blown into the slurry, regenerated particles whose surface is coated with calcium carbonate are obtained, and thus the whiteness is further increased. And since the said calcium carbonate is light calcium carbonate with high oil absorption property, the oil absorption degree of the reproduction | regeneration particle | grains obtained improves.

[Invention of Claim 5]
Regenerated particles produced by dewatering and heat treating paper sludge,
As the main component of the papermaking sludge, using deinking floss discharged in the manufacturing process of used newspaper pulp ,
The content ratio of calcium carbonate in the inorganic particles contained in the papermaking sludge is adjusted to exceed 70% by mass,
In the obtained regenerated particles, metakaolin and hydrous magnesium silicate are the main components of the core, and the surface of the core is coated with calcium carbonate.
Regenerated particles characterized by that.

(Main effects)
When the main component of papermaking sludge is deinking floss discharged in the manufacturing process of used newspaper pulp, as mentioned above, problems of hardening and low whiteness, and problems of thickening and solidifying when slurried Is resolved. Further, the obtained regenerated particles are mainly composed of metakaolin and hydrous magnesium silicate , and the surface of the nucleus is coated with calcium carbonate. The surface of the particle nucleus having low whiteness is high in whiteness. It means that it is coated with calcium carbonate, and the whiteness as regenerated particles is increased.

  According to the present invention, it is possible to easily and stably obtain regenerated particles in which the problem of hardening, low whiteness, and the problem of thickening and solidifying when slurried are solved, and such regenerated particles. This is a method for producing regenerated particles.

It is a processing flow figure of the manufacturing method of regenerated particles.

Next, an embodiment of the present invention will be described.
As shown in FIG. 1, in the manufacturing method of the present embodiment, regenerated particles R are manufactured from a papermaking sludge S whose main raw material is newspaper deinking floss.

(Paper sludge)
Here, “newspaper deinking froth” is a floss separated from pulp fibers during the deinking process in the manufacturing process of newspaper deinking pulp (NDIP), and the manufacturing process of magazine deinking pulp (MDIP) and the like. Does not contain the floss separated from the pulp fibers during the deinking process. Further, the main raw material means that the content ratio (based on solid content mass) with respect to the total papermaking sludge raw material is preferably 50% or more, more preferably 70% or more, and particularly preferably 90% or more. It means that there is.

  In recent years, newspaper deinking floss has a tendency to have a relatively high amount of calcium carbonate and a relatively small amount of kaolin due to the fact that the paper used in the production of newsprint has become neutral paper making. The ratio exceeds 70% by mass, and the kaolin ratio changes at less than 30% by mass. Therefore, if the main raw material of paper sludge is newspaper deinking floss, the amount of cementitious material produced from calcium oxide and kaolin is reduced, and the problem of the hardened and low whiteness of the regenerated particles obtained, the slurry The problem of thickening and solidifying when it is transformed is improved.

  Also, in the production of newspaper deinked pulp, in order to continuously obtain newspaper deinked pulp of stable quality, there is a tendency for newspapers of a certain quality that have been selected to be used as raw materials. Tend to stabilize. Therefore, if newspaper deinking floss is used as the main raw material, the quality of the regenerated particles can be stabilized.

  Furthermore, newspaper deinking floss has a relatively low ash content of the newspaper used as a raw material, and newspaper ink contains oils and fats and carbon black. Have Therefore, fuel such as heavy oil used for burning the papermaking sludge S can be reduced.

  By the way, the kaolin that causes the generation of cementitious substances is mainly derived from coated paper such as leaflets mixed in old newspaper. Therefore, it is possible to further increase the ratio of calcium carbonate and the ratio of kaolin by selecting and removing the coated paper mixed in the used newspaper. Preferably, the proportion of kaolin in the inorganic particles contained in the newspaper deinking floss is less than 20% by mass, and the proportion of other inorganic particles is more than 80% by mass, more preferably the proportion of kaolin is 20% by mass. The coated paper is preferably selected and removed from the used newspaper so that the ratio of calcium carbonate is 80% by mass or more.

  In this respect, talc, which is the same silicate mineral / viscosity mineral as kaolin, is contained in the other inorganic particles. For example, even when calcium carbonate: talc: kaolin = 80: 5: 15, the ratio of kaolin is 20 mass. It is included when it is less than%. This is because talc is not decomposed at the combustion temperature (described later) necessary for the production of regenerated particles and does not affect the production of cementitious substances.

  On the other hand, as the raw material for the papermaking sludge S, papermaking sludge other than newspaper deinking floss can be used as long as it is not the main raw material. Specifically, for example, papermaking sludge generated in other processes such as factory effluent and papermaking raw material preparation process, and deinking floss such as magazine deinking floss can be used.

  However, since magazine deinking floss is mainly made of coated paper and contains a large amount of kaolin, using magazine deinking floss as a raw material for paper sludge S can easily produce cementitious substances. Become. Therefore, it is preferable not to use the magazine deinking floss as a raw material for the papermaking sludge S.

  When using magazine deinking floss, special attention should be paid to the calcium carbonate ratio and kaolin ratio. Specifically, for example, a papermaking sludge generated from a neutral papermaking process using calcium carbonate, or a papermaking sludge such as washing water of a calcium carbonate storage tank or a screen cake is mixed, and the ratio of calcium carbonate Should be raised relatively.

[Dehydration process]
The papermaking sludge S is dehydrated using a known dehydrator or the like in the dehydration step 10. However, this dehydration is performed, for example, with a screen until the moisture content of the papermaking sludge S is 65 to 90%, and then the moisture content of the papermaking sludge S is 30 to 60% (preferably 30 to 50%) with a screw press. And more preferably 35 to 45%), and it is preferable to carry out in multiple stages. By performing the dewatering of the papermaking sludge S in multiple stages, rapid dewatering can be avoided, the outflow of inorganic particles can be suppressed, and the floc of the papermaking sludge S can be prevented from becoming too hard.

Here, the “water content” of the papermaking sludge S is such that a constant temperature dryer is used, and the sample (papermaking sludge S) is allowed to stand in the dryer and kept at about 105 ° C. for 6 hours or more so that mass fluctuation is not recognized. It is the value calculated from the mass measurement result before and after drying by the following formula, with the mass after drying as the mass after drying.
Moisture content (%) = (mass before drying−mass after drying) ÷ mass before drying × 100

[Crushing process]
The papermaking sludge S after dehydration can be crushed prior to heat treatment in the heat treatment step 30. The crushing is performed so that the average particle diameter of the papermaking sludge S is 2.5 to 12.5 mm, preferably 2.5 to 7.0 mm, and more preferably 2.5 to 4.0 mm. Do as follows. When the average particle diameter of the papermaking sludge S is less than 2.5 mm, excessive heat treatment is likely to be performed in the subsequent heat treatment step 30. On the other hand, when the average particle diameter of the papermaking sludge S exceeds 12.5 mm, it becomes difficult to uniformly heat-treat the papermaking sludge S from the surface portion to the core portion.

  Here, the “average particle diameter” of the papermaking sludge S is obtained by sieving with a sieve having different eye holes, and the mass of each sieving sample (papermaking sludge) is measured. It is the size of the eye opening of the sieve at a stage corresponding to 50% by mass, and is a value measured using a metal plate sieve based on JIS Z 8801-2: 2000.

[Heat treatment (drying) process]
The crushed papermaking sludge S is subjected to heat treatment such as drying and combustion in the heat treatment step 30. Although this heat treatment can be performed continuously with one apparatus, it is preferable that the heat treatment is divided into at least a drying process 31 and a combustion process 32, and the drying process and the combustion process are performed with separate apparatuses. By performing the drying process prior to the combustion process, the fuel required for the combustion process can be reduced, and the calcium carbonate can be reliably decomposed into calcium oxide.

  The drying temperature of the papermaking sludge S is, for example, 200 to 600 ° C, preferably 200 to 450 ° C, more preferably 200 to 300 ° C. Moreover, this drying process is performed so that the moisture content of the papermaking sludge S is, for example, 0 to 5%, preferably 0 to 3%, and more preferably 0 to 1%. it can.

  As a drying apparatus for the papermaking sludge S, for example, a stalker furnace, a fluidized bed furnace, a cyclone furnace, a kiln furnace, an airflow drying apparatus, or the like can be used. However, at the next moment when moisture is evaporated from the papermaking sludge S using an airflow drying device or the like, for example, if the papermaking sludge S after drying is discharged from the drying device after 1 to 3 seconds, There is no risk of unintentional heat treatment of organic matter such as thermal decomposition and combustion, which is preferable. The “water content” of the papermaking sludge S is the same as that in the “dehydration step” described above.

  The drying in the drying step 31 can be performed using the exhaust gas G generated in the subsequent combustion step 32.

[Heat treatment (combustion) process]
The dried papermaking sludge S is sent to the combustion process 32 for combustion treatment. This combustion treatment can be performed by using a plurality of devices (furnace) and divided into a plurality of steps, but it is preferably performed in one step / device from the viewpoint of simplification of control.

  The combustion treatment in the combustion step 32 is preferably performed so that 80% by mass or more (preferably 90% by mass or more) of calcium carbonate is decomposed into calcium oxide. In this embodiment, since newspaper deinking floss is used as the main raw material of the papermaking sludge S, the kaolin content is low and the production of cementitious substances is suppressed. Therefore, it is not necessary to suppress the decomposition of calcium carbonate, and conversely, the decomposition of calcium carbonate proceeds as much as possible. If the decomposition from calcium carbonate to calcium oxide is promoted, the particle surface can be more reliably coated with calcium carbonate in the subsequent carbon dioxide blowing step, and the diameter of the regenerated particles will be reduced. be able to.

  Here, the decomposition rate of calcium carbonate is SII Nano Technology Co., Ltd. (model TG / DTA6200), and the measurement conditions are (1) Temperature rising rate 25 to 1050 ° C .: 20 ° C./min, (2) Supply Gas air (oxygen concentration: about 5 vol%), (3) Supply gas flow rate: about 48 ml / min.

  The combustion temperature of the papermaking sludge S is preferably 750 to 900 ° C., more preferably 800 to 900 ° C., and particularly preferably 800 to 850 ° C. in order to reliably decompose calcium carbonate. When the combustion temperature is lower than 750 ° C., the decomposition of calcium carbonate becomes insufficient, and the precipitation (coating) of calcium carbonate in the carbon dioxide blowing step 50 may be insufficient. On the other hand, burning so that the combustion temperature exceeds 900 ° C. is uneconomical because it requires an excessive amount of fuel.

  The oxygen concentration during the combustion treatment is preferably 3 to 18%, more preferably 4 to 15%, and particularly preferably 5 to 12%. Since the exhaust gas G generated in the combustion process 32 contains carbon dioxide, it can be used as a carbon dioxide-containing gas used in the subsequent carbon dioxide blowing process 50. However, if the oxygen concentration during the combustion treatment is less than 3%, incomplete combustion occurs and the carbon monoxide concentration increases, so that it cannot be used as the carbon dioxide-containing gas used in the carbon dioxide blowing step 50. there is a possibility. On the other hand, if the oxygen concentration exceeds 18%, the carbon dioxide concentration of the exhaust gas G becomes too low, which may be inappropriate for use in the carbon dioxide blowing process.

  As a combustion apparatus for the papermaking sludge S, for example, a stalker furnace, a fluidized bed furnace, a cyclone furnace, a kiln furnace, or the like can be used. However, it is preferable to use a horizontal rotary kiln furnace, and it is more preferable to use an internally heated kiln furnace than an externally heated kiln furnace. In this embodiment, it is not necessary to control the combustion process in detail and it is not necessary to suppress the decomposition of calcium carbonate, and therefore, an internal heat kiln furnace is selected with an emphasis on thermal efficiency. In addition, when using an internal heating kiln furnace, the combustion time of the papermaking sludge S can be set to 30 to 120 minutes, for example.

[Slurry process]
The burned papermaking sludge S (hereinafter referred to as “burnt product S”) is sent to the slurrying step 40 and dissolved in water to form a slurry.

  In this regard, in the conventional manufacturing method, it is necessary to pulverize the combustion product S prior to slurrying. However, in the manufacturing method of the present embodiment, this pulverization can be omitted. In this embodiment, since the calcium oxide in the combustion product S is used for the precipitation of calcium carbonate (crystals) in the subsequent carbon dioxide blowing step 50, the particle diameter is small without being pulverized. If this pulverization is omitted, the pulverization energy can be reduced.

  However, the combustible material S can be pulverized from the viewpoint of uniformly slurrying (dissolving) the combustible material S and from the viewpoint of performing it quickly. Even if this pulverization is performed, the pulverization is not a fine pulverization which has been conventionally performed, but a coarse pulverization is sufficient, so that the pulverization energy can be reduced and the durability of the pulverizer is improved.

  The coarse pulverization of the combustion product S can be performed so that the average particle diameter is 1 to 100 μm or less, preferably 2 to 50 μm, more preferably 3 to 30 μm. The conventional fine pulverization is generally performed until the average particle size becomes 10 μm or less.

  Here, the “average particle diameter” of the combustion product S is a volume average measured for the slurry of the sample (combustion product) using a particle size distribution diameter (model number: SA-LD-2200, manufactured by Shimadzu Corporation) of a laser diffraction method. The particle diameter (D50).

  As the pulverizer for the combustible S, for example, a dry pulverizer such as a jet mill or a high-speed rotary mill, a wet pulverizer such as an attritor, a sand grinder, or a ball mill can be used.

  The combustible S that has been pulverized as necessary is dissolved in water to form a slurry. By this slurrying, the calcium oxide in the combustion product S is suspended in water and becomes an aqueous calcium hydroxide solution. Note that the combusted material S before the slurrying is preferably an aggregate.

  Slurry of the combustion product S can be performed so that the concentration of the combustion product S is 2 to 25%, preferably 3 to 20%, more preferably 5 to 15%. If the concentration exceeds 25%, the viscosity of the slurry becomes too high, and the subsequent carbonation reaction may not occur efficiently. On the other hand, when the concentration is less than 2%, the carbonation efficiency may be lowered, the dehydration efficiency after the carbonation may be lowered, and the operation efficiency may be lowered.

[CO2 blowing process (finishing process)]
In the carbon dioxide blowing step 50, the slurry of the combustion product S blows carbon dioxide and precipitates calcium carbonate (carbonation treatment). Note that the storage tank used when slurrying the combustion product S and the storage tank used when blowing carbon dioxide into the slurry may be the same or different, but are usually the same. is there.

  In blowing carbon dioxide into the slurry of the combustion product S, carbon dioxide-containing gas such as exhaust gas G discharged from the combustion process 32 can be used. The carbon dioxide concentration of the carbon dioxide-containing gas is preferably 5 to 30%, more preferably 10 to 30%, and particularly preferably 20 to 30%. If the concentration of carbon dioxide is less than 5%, calcium carbonate may not be sufficiently precipitated. On the other hand, when the concentration of carbon dioxide exceeds 30%, there is a possibility that excessive particles are generated due to precipitation of calcium carbonate having a columnar or needle-like crystal structure. In addition, when using the exhaust gas G discharged | emitted from the combustion process 32 as a carbon dioxide containing gas, as mentioned above, the combustion process in the combustion process 32 is preferably performed on the conditions of oxygen concentration 3-18%, and it cools suitably. And dust removal.

Calcium carbonate deposited by blowing carbon dioxide covers the surface of the regenerated particles. Hereinafter, this mechanism will be described.
When high temperature combustion is performed in the presence of calcium carbonate and kaolin, calcium carbonate is decomposed into calcium oxide, and kaolin reacts with the calcium oxide and silicic acid to produce various hydrated hard substances. However, when newspaper deinking floss is used to increase the proportion of calcium carbonate relatively and lower the proportion of kaolin, the proportion of calcium oxide that does not originate from hydrated hard substances (does not react with kaolin) increases. The calcium oxide (CaO) becomes calcium hydroxide (CaOH) by slurrying the combustion product S. Therefore, the slurry of the combustion product S contains OH ⁻ which shows strong alkalinity as shown in the following formula (1).
_{CaO + H 2 O → Ca 2} + + 2OH - + CO 2 ... (1)
When carbon dioxide (CO ₂ ) is blown into the slurry of the combustion product S, calcium carbonate (CaCO ₃ ) is precipitated and the pH is lowered as shown in the following formula (2).
_{^{Ca 2 + + 2OH - + CO}} 2 → CaCO 3 + H 2 O ... (2)
The calcium carbonate thus deposited covers the surface of the particle nucleus composed mainly of metakaolin and hydrous magnesium silicate.

  Thus, according to the manufacturing method of the present embodiment, regenerated particles R whose surfaces are coated with calcium carbonate are obtained. Although this regenerated particle R has an irregular shape, its surface is coated with calcium carbonate, so that the whiteness of the regenerated particle R is high, unlike conventional regenerated particles in which calcium carbonate, kaolin, etc. are simply aggregated. Moreover, since there is no knife edge by wet grinding, there is also an advantage that the wire wear resistance is excellent. Furthermore, since the calcium carbonate which coat | covers the said surface is light calcium carbonate with high oil absorption, oil absorption is also improved. The regenerated particles R can be temporarily stored in a silo or the like, and can be appropriately used for a papermaking filler or a pigment.

Next, examples of the present invention will be described.
Using an internally heated horizontal rotary kiln furnace, as shown in Tables 1 and 2, regenerated particles were produced under various production conditions, and various tests were performed. Details are as follows.

(Calcium carbonate content)
The papermaking sludge was burned at 525 ° C. to obtain a combustion product, and the element-analyzer (X-ray microanalyzer) was used to determine the oxide-converted mass ratio of various elements contained in the combustion product. Based on this result and the molecular weights of calcium carbonate, kaolin, talc and silicic acid, proportional calculation was performed to calculate the content ratio of calcium carbonate in the papermaking sludge.

(Decomposition rate of calcium carbonate)
From the difference between the TG-DTA mass reduction rate (600 to 800 ° C.) of the combustion product burned at 525 ° C. and the TG-DTA mass reduction rate (600 to 800 ° C.) of the combustion product burned by the method described in the table The decomposition rate was determined.

(Moisture percentage)
This is a value calculated by the following formula, with the sample placed in a constant temperature dryer and held at about 105 ° C. for 6 hours or longer when mass fluctuation is no longer recognized as the post-drying mass.
Moisture content (%) = (mass before drying−mass after drying) ÷ mass before drying × 100

(temperature)
It is the value which measured the temperature in a furnace main body using the thermocouple.

(Oxygen concentration)
It is the value which measured the oxygen concentration in a furnace main body using the automatic oxygen concentration measuring apparatus (model number: ENDA-5250, Horiba Seisakusho).

(Dispersibility)
It is a value measured using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd., TVM-10M) under the conditions of an atmospheric temperature of 20 ° C. and a rotor rotational speed of 60 rpm. The lower the viscosity (mPa · s), the better the dispersibility.

(Post-reaction pH / Product pH)
The post-reaction pH is the pH at the end of the carbonation reaction after the carbon dioxide blowing in the carbon dioxide blowing step, and the product pH is the pH of 9.0 or more after the carbonation reaction is finished per hour. It means the pH when the pH fluctuation value is 0.5 or less, respectively.

(Average particle size)
It is a volume average particle diameter (D50) measured using a particle size distribution diameter (model number: Microtrac MT-3000II, manufactured by Nikkiso) of a laser diffraction method.

(Whiteness)
It is a value measured by using a color difference meter (SP-80, manufactured by Tokyo Denshoku Co., Ltd.), grinding a powder sample with a mortar and packing it in a glass cell.

(Oil absorption)
It is a value measured according to the kneading method of JIS K 5101. That is, 2 g to 5 g of a sample dried at 105 ° C. to 110 ° C. for 2 hours was taken on a glass plate, and refined linseed oil (oxidized 4 or less) was dropped from the buret to the center of the sample little by little, and kneaded with a spatula each time. . This dripping and kneading were repeated, and when the whole was first assembled into one rod shape, the end point was determined, and the dripping amount of the refined linseed oil at this point was determined and calculated by the following formula.
Oil absorption amount = [linseed oil amount (ml) × 100] / sample (g)

((Wire) wear degree)
It is a value measured after 3 hours using a plastic wire wear meter (manufactured by Nippon Filcon) under a slurry concentration of 2%.

  The present invention is applicable as a method for producing regenerated particles using papermaking sludge as a raw material and as regenerated particles.

  DESCRIPTION OF SYMBOLS 10 ... Dehydration process, 30 ... Heat treatment process, 31 ... Drying process, 32 ... Combustion process, 40 ... Slurry process, 50 ... Carbon dioxide blowing (finishing) process, S ... Papermaking sludge, R ... Recycled particles.

Claims (5)

A method for producing regenerated particles by dewatering and heat-treating paper sludge,
The main raw material of the papermaking sludge is deinked floss discharged in the newspaper wastepaper manufacturing process ,
The content ratio of calcium carbonate in the inorganic particles contained in the papermaking sludge exceeds 70% by mass.
A method for producing regenerated particles. The heat treatment is divided into at least a drying process and a combustion process,
The combustion treatment is performed so that 80% by mass or more of calcium carbonate is decomposed into calcium oxide.
The method for producing regenerated particles according to claim 1. The heat treatment is divided into at least a drying process and a combustion process,
The combustion treatment is performed at a combustion temperature of 750 to 900 ° C. and an oxygen concentration of 3 to 18%.
The method for producing regenerated particles according to claim 1 or 2. Slurry the combustion product after the heat treatment, and blow carbon dioxide into the slurry.
The manufacturing method of the reproduction | regeneration particle | grains of any one of Claims 1-3. Regenerated particles produced by dewatering and heat treating paper sludge,
As the main component of the papermaking sludge, using deinking floss discharged in the manufacturing process of used newspaper pulp ,
The content ratio of calcium carbonate in the inorganic particles contained in the papermaking sludge is adjusted to exceed 70% by mass,
In the obtained regenerated particles, metakaolin and hydrous magnesium silicate are the main components of the core, and the surface of the core is coated with calcium carbonate.
Regenerated particles characterized by that.

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