JP5351222B2 - Regenerated particle aggregate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recycled particle aggregate having characteristics required as a filler for papermaking or a pigment for coating. <P>SOLUTION: A recycled particle aggregate is obtained through dehydration, drying, burning and grinding operations of a raw material 10 comprising deinked floss as a main raw material separated from a pulp fiber in a deinking process of wastepaper treatment facilities for producing a wastepaper pulp. The recycled particle aggregate is obtained through at least two stages of burning steps including a first burning step 14 of drying and oxidation burning at a burning temperature of 500 to 650&deg;C so that the rate of an unburnt matter in a burnt substance is 2 to 20 mass%, and a second burning step 32 of reburning at a burning temperature of 550 to 750&deg;C for a burning time of 10 to 60 minutes. The recycled particle aggregate has a total content of hard substances, Ca<SB POS="POST">2</SB>Al<SB POS="POST">2</SB>SiO<SB POS="POST">7</SB>and CaAl<SB POS="POST">2</SB>Si<SB POS="POST">2</SB>O<SB POS="POST">8</SB>, of 2.0 mass% or less and brightness of 70% or more. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a regenerated particle aggregate obtained using deinked floss as a main raw material.

Paper sludge discharged from various processes in a pulp and paper mill contains a large proportion of inorganic fillers and inorganic pigment particles. These paper sludge is recovered and incinerated in fluidized bed furnaces, multistage combustion furnaces, stalker furnaces, etc. The organic substances in the papermaking sludge are burned in a furnace to reduce the volume of the papermaking sludge and are recovered as energy.
However, since papermaking sludge contains a large amount of inorganic substances, a large amount of incinerated ash (inorganic substances) remains even after combustion, and there is a limit to volume reduction. Therefore, efforts have been made to use this incinerated ash as an auxiliary agent for cement raw materials and as a soil conditioner. However, the amount of incineration ash used as an auxiliary to these cement raw materials and soil conditioners is very small, and in the end, most of the incineration ash is landfilled.
Therefore, not only recovering as thermal energy by incineration, but also reusing inorganic substances in paper sludge as paper fillers, pigments, plastic fillers, etc. is related to environmental problems as well as improving the waste paper utilization rate in the paper industry. This is an important improvement issue.
However, the incineration ash of papermaking sludge contains organic substances that remain without being burned as carbon, so the whiteness is low, or the sintering of inorganic substances progresses, the particle sizes are uneven and large, and in that state It is not suitable for use as a filler for papermaking, a pigment for coating, or a filler for plastics.

Therefore, Patent Document 1 discloses a method of using after incineration ash is reburned to improve whiteness.
However, in the method of recombusting the incinerated ash of Patent Document 1, it is necessary to set the recombustion temperature to 500 to 900 ° C. in order to completely burn the unburned carbon, and the whiteness of the incinerated ash is about 50%. It has been found that it is not suitable for use as a filler for papermaking or as a pigment for coating. It was also found that when the re-combustion temperature was set to over 900 ° C., the incineration ash (inorganic material) was sintered and melted and became extremely hard. In addition, when reincinerated ash is used as a filler, this reincinerated ash has very hard properties, so the progress of wear of the papermaking wire is fast and the life of the papermaking wire is very short. It wasn't. In addition, when this re-incinerated ash is used as a coating pigment, the re-incinerated ash is very hard, which causes damage to the coating equipment due to wear. There arises a problem that the smoothness is inferior.
In this regard, it may be possible to pulverize the re-incinerated ash and reduce its particle size to reduce wear and improve smoothness. However, when used as an internal filler, the yield during papermaking is low. Since the incinerated ash itself is extremely hard, the energy cost for pulverization becomes extremely high.

In Patent Document 2, papermaking sludge is supplied into a reactor into which an oxygen-containing gas has been injected, and is oxidized at 250 to 300 ° C. under a heating and pressurization of about 3000 psig for 0.25 to 5 hours. Has been proposed to recycle as a pigment for papermaking.
However, since this method is based on wet air oxidation treatment with the paper sludge remaining in the liquid phase, organic matter removal is not sufficient, and the resulting pigment has low whiteness and uneven particle size, making papermaking This is unsuitable for use as a filler or pigment, and has a problem that the reaction operation is complicated and expensive.

  On the other hand, Patent Document 3 proposes a method in which after making papermaking sludge into PS charcoal, it is further incinerated in an internal heat kiln furnace to produce white clay as a papermaking raw material. However, this method has a great demerit that not only energy cannot be effectively extracted from the papermaking sludge but also input energy is required because the papermaking sludge is fried. In addition, by smoldering, the volatile matter is removed and the organic matter is difficult to burn (oxidize), so-called “residual carbon”, which makes it difficult to burn in the post-process and has a long combustion time due to residual carbon It is difficult to obtain high whiteness unless it is applied, and the generated clay is also large due to uneven particle size, and contamination from carbon and sulfur oxides from heavy oil burners used in internal heat kilns occurs. There is a problem that it cannot be used as a papermaking pigment.

  As disclosed in Patent Document 4, a method is known in which wastewater treatment sludge is continuously dried, carbonized, and burned in a rotary kiln furnace. Since the wastewater treatment sludge used in this method is composed of sludge having various sources, there is a problem that the resulting granulated / molded material also fluctuates due to fluctuations in the source and amount generated. In this patent document, granulation and shaping prior to combustion are considered to be performed for uniform combustion, but the solid content concentration described in the embodiment is 40 to 60% (in other words, If the moisture content is 60-40% in the rotary kiln, the sludge particles are forced by the rotation of the kiln regardless of whether the sludge is dry or carbonized. The process will continue. Therefore, if the drying is insufficient, a large amount of unburned matter remains inside the particles, resulting in incomplete combustion and a decrease in whiteness.On the other hand, overdrying results in complete combustion but overburning. As a result, the hardness of the obtained regenerated particle aggregate increases, and when this regenerated particle aggregate is used, there is a problem that wire wear in a paper machine and cutter blade wear when cutting paper are likely to occur.

The biggest problem when using papermaking sludge described in the preceding Patent Documents 1 to 4 as a raw material is that the papermaking sludge used as a raw material flows out through the wire in the papermaking process, and the washing process in the pulping process Collected from wastewater containing solids generated in wastewater, separated and recovered by solids separation equipment using precipitation or flotation, etc., in wastewater treatment process, removed foreign matter in wastepaper treatment process It is a point where various sludges such as are mixed.
Among these papermaking sludges, for example, those that flow out through the wire in the papermaking process are mixed with a paper strength agent and the quality varies due to changes in the papermaking product in the papermaking process. In addition, the papermaking sludge collected from the wastewater treatment process is mixed with a flocculant, and a large fluctuation occurs due to papermaking products in the whole factory, fluctuations in production volume, or in-process washing of production facilities.
In the papermaking sludge generated from the washing process in the pulping process, fluctuations occur in chip moisture and pulp production conditions, and various fillers and substances that cannot be made into pigments are mixed, resulting in quality fluctuations. Therefore, if all the papermaking sludge is used without selection, the quality as a papermaking filler or coating pigment is greatly reduced, and the quality fluctuation is extremely large and unstable.
That is, the regenerated particles obtained by a conventionally known method are not suitable for use as fillers for papermaking, pigments for coating, plastics, etc., and lack quality stability.

JP-A-11-310732 Japanese Examined Patent Publication No. 56-27638 Japanese Patent Laid-Open No. 54-14367 Registration No. 3812900

  The main problem to be solved by the present invention is to provide an aggregate of regenerated particles having characteristics necessary particularly as a filler for paper manufacture or a pigment for coating.

The present invention that has solved this problem is as follows.
[Invention of Claim 1]
A recycled particle aggregate obtained by dehydrating, drying, burning, and pulverizing a raw material mainly made of deinked floss separated from pulp fibers in a deinking process of a used paper processing facility for producing used paper pulp,
Drying and oxidative combustion in an internal heat kiln furnace in which the main body is placed horizontally and rotates around the central axis so that the unburned rate of the combustion product becomes 2 to 20% by mass at a combustion temperature of 500 to 650 ° C. and a residence time of 30 to 90 minutes A first combustion process, and a second combustion process in which combustion is performed again at a combustion temperature of 550 to 750 ° C. and a combustion time of 10 to 60 minutes higher than the combustion temperature in the first combustion process. Obtained through the process,
The raw material supplied to the internal heat kiln furnace is adjusted so that the moisture content is 25 to 50%, the average particle diameter is 3 to 40 mm, and the ratio of the particle diameter is 50 mm or less is 70% by weight or more,
The regenerated particle aggregate has a weight loss ratio of 5% (TG) or more, a total content of the following hard substances of 2.0% by mass or less, and whiteness in a differential thermothermal gravimetric analysis at 25 ° C. to 800 ° C. Is 70% or more,
A regenerated particle aggregate characterized by that.
Hard materials: Ca ₂ Al ₂ SiO ₇ , CaAl ₂ Si ₂ O ₈

[Invention of Claim 2 ]
The surface of the regenerated particle aggregate is coated with silica,
The mass ratios of calcium, silicon, and aluminum are converted to oxides by elemental analysis using an X-ray microanalyzer, and 30 to 82: 9 to 35: 9 to 35 in the state where the silica is not coated. 30-62: 29-55: 9-35 in the coated state,
1 Symbol mounting playback particle aggregate claims.

  According to the present invention, a regenerated particle agglomerate having characteristics necessary particularly as a filler for paper manufacture or a pigment for coating is obtained.

It is a schematic diagram of a manufacturing facility.

Next, prior to the description of the embodiments of the present invention, the positioning of the present invention will be described.
For example, when papermaking sludge is combusted, (1) in the invention described in Japanese Patent Application Laid-Open No. 2003-119695, the dried product is poor in that oxygen is not substantially present so that the oxygen concentration in the furnace is 0.1% by volume or less. In an oxygen state, specifically, drying and carbonization are performed by an indirect heating furnace (external heat combustion furnace). Next, a method has been proposed in which carbon derived from an organic substance contained in a carbide is oxidized and decarbonized, specifically, a whitening treatment is performed using an indirect heating furnace. The invention also teaches the use of an internal heat rotary kiln furnace for the latter whitening treatment.
On the other hand, the present applicant also teaches (2) JP 2002-275785 to use a rotary kiln furnace for recombustion after carbonization.
Further, the present applicant, as (3) Patent No. 3808852, “Deinking sludge is used as raw material sludge and dried, and the dried deinking sludge is removed from the upper part of the cyclone combustion furnace. A primary combustion step of obtaining a primary combustion product containing unburned content by being supplied to the inside and burning while swirling down, and receiving the primary combustion product containing unburned content from the lower end thereof in communication with the cyclone type combustion furnace And a secondary combustion step of burning until a predetermined whiteness is obtained using the heat of combustion of the primary combustion step while promoting contact with oxygen by mechanical stirring. A method for producing a white pigment or a white filler from sludge "was proposed.
In addition, in (4) Japanese Patent Application Laid-Open No. 2004-176208, when the filler is produced from “the wastewater treatment sludge in the coated paper manufacturing process”, the formed sludge is “dried, carbonized and burned in one rotary kiln furnace”. Propose that.

The above (1), (2) and (4) do not use deinking floss separated from pulp fibers in the deinking process of the used paper processing equipment for producing used paper pulp, but mainly use the above-mentioned papermaking sludge. It is a raw material. The obtained regenerated particles are considered to be different from the regenerated particles “aggregates” as in the present invention.
On the other hand, according to the method (3), regenerated particle aggregates similar to those obtained by the present invention can be obtained. However, in this method, a cyclone type combustion furnace is used to burn dry matter and then perform secondary combustion.
However, in this case, drying and combustion are performed in separate devices, which not only increases the equipment cost, but is thought to be derived from the form of the cyclone type combustion furnace itself, but the cyclone type is tens to thousands of microns. Since the raw material and air are supplied from the supply port as a swirling flow and burned while being effectively mixed with air by the swirling action of the air, the fine particles contained in the raw material are discharged out of the system together with the exhaust gas, reducing the product yield. The problem is that the combustion time (heating time) of the deinking floss that is the main raw material is short, the unburned matter is likely to occur, the quality (particularly the shape) of the final combustion product is not constant, It has been found that the whiteness of the combustion product may vary, and that the surface of the regenerated particles is excessively burned due to internal heat combustion, and the generation of hard substances cannot be avoided.

Therefore, the present invention uses a first combustion furnace in which drying and combustion of the raw material after dehydration are preferably performed in a series, and the combustion time (residence time) in the first combustion furnace exceeds 30 minutes. The internal heat (direct heating) kiln furnace that is horizontally placed and rotates around the central axis performs drying and combustion of the raw material after dehydration, and then burns again the combustion product obtained from the first combustion furnace ( A second combustion furnace having a residence time of 10 minutes or more, preferably an external heat (indirect heating) kiln furnace in which the main body is placed horizontally and rotates around the central axis, particularly an external heat electric kiln in which the combustion temperature can be easily adjusted A method of burning with a furnace can be adopted.
In the following, the case where an internal heat kiln furnace is selected as the first combustion furnace and an external heat kiln furnace is selected as the second combustion furnace will be described in detail. A known combustion furnace can be used as long as it is an at least two-stage combustion furnace that performs two-combustion furnace with external heat. Further, as described above, the internal combustion furnace in which the combustion time (residence time) in the first combustion furnace is 30 minutes or more, and the external heat combustion furnace in which the combustion time (residence time) in the second combustion furnace exceeds 10 minutes. It is more preferable if a known combustion method such as a fluidized bed incinerator, a multistage combustion furnace as an internal heat combustion furnace, an indirect heating type combustion furnace using heavy oil as a heat source as an external heat combustion furnace, etc. it can.
According to the internal heat kiln furnace suitably used as the first combustion furnace, drying and combustion can be performed in one furnace, and the drying and combustion proceed slowly and stably from the supply port to the discharge port. And the pulverization of the combustion product is suppressed. Moreover, when combusted in an external heat kiln furnace that is suitably used as the second combustion furnace, the combusted material can be discharged from the end of the combusted material with a constant residence time through the discharge port of the other end, and further uniformed by the external heat. Since the heat is applied, the combustion becomes uniform, the generation of hard substances is suppressed, and the variation in combustion is not caused. Furthermore, the combustion product is gently agitated by friction caused by the rotation of the inner wall of the kiln furnace, so that it is difficult to produce fine powder. As a result, the quality and shape of the final combustion product become stable.
As described above, the drying and combustion operations are performed in the first combustion furnace and the second combustion furnace, preferably in the internal heat kiln furnace and the external heat kiln furnace, using at least two stages of combustion furnaces. By carrying out, uniform and stable regenerated particle aggregates can be obtained.
The internal heat or external heat kiln furnace used as a suitable combustion furnace can lift and agitate the combusted material without slipping by making the internal refractory into a hexagonal or octagonal shape instead of a circumferential shape. By not providing a lifter for stirring a product, generation of dust can be suppressed, dust can be prevented from being mixed into exhaust gas, and product yield can be improved.

Here, the selection of the combustion furnace most focused on when the present inventors obtain a suitable regenerated particle aggregate will be described.
Conventionally used combustion furnaces can be broadly classified into four types: stalker furnaces (fixed bed), fluidized bed furnaces, cyclone furnaces, and kiln furnaces. After studying the production method to obtain the aggregate,
(1) For the stalker furnace (fixed bed), it is difficult to adjust the degree of combustion of the deinking floss, and the combustion products are not uniform. Is not suitable. Since air is blown up and burned under the combustion material through the grate, calcium carbonate or the like becomes fly ash and is sent to the exhaust gas facility together with the exhaust gas. Since the combustion furnace is burned while passing through the stoker (stepped shape) of the combustion furnace with a predetermined width, the ash is not sufficiently stirred and the combustion varies in the width direction.
(2) Since the fluidized bed furnace uses a particulate fluid medium such as silica sand as the fluid medium in the furnace, there is a problem that the silica sand is mixed into the reclaimed filler and the quality is deteriorated. Uniform stirring is not possible. After the cinnabar sand is mixed in a fluidized bed and combusted, the cinnabar sand and the burned material are separated, and the cinnabar sand is returned to the combustion furnace, and only the burned material is taken out. It is difficult to adjust the degree of combustion because it is burned in a floating state with dredged sand, resulting in variations in quality. Combustion products are pulverized and become fly ash due to friction and collision with hard silica sand. It is discharged out of the system and the yield decreases.
(3) As for the cyclone furnace, the fixed carbon in the combusted material cannot be burned sufficiently because it passes through the furnace in an instant, leading to a decrease in whiteness. Further, fine particles are not separated by the cyclone and discharged from the exhaust gas. The yield decreases because it goes to the exhaust gas treatment process together.
As a result of intensive studies on the above problems, the combustion furnace is selected as the most suitable combustion means for combustion in the kiln furnace. Further, the first combustion furnace is the internal heat kiln, and the subsequent combustion furnace for the following reasons. It has been found that the second combustion furnace is preferably an external heat kiln.
Since the external heat kiln furnace has a configuration in which heating equipment is provided outside the kiln furnace, the structure of the kiln furnace is complicated, and the combustion product is indirectly dried and burned, so a large amount of heat source is required. When the external heat kiln furnace is used as the first combustion furnace for the drying and combustion treatment of the raw material having a high water content after dehydration according to the present invention, the drying / combustion efficiency is lowered and the productivity is poor. The temperature control becomes difficult and requires a large energy cost, and the cost effectiveness is extremely low.
In addition, when the internal heat kiln furnace is used for the second combustion furnace, a large amount of diluted air is required to adjust the temperature in the furnace when the remaining carbon is combusted. Since it is difficult to transmit uniformly to the internal heat kiln furnace, and furthermore, it is difficult to suppress fluctuations in the temperature in the furnace, there is a problem that hard substances are generated and combustion unevenness is likely to occur due to overcombustion of combustion products.
In addition, heavy oil combustion residual carbon and sulfur oxides from heavy oil burners used for normal heating cause contamination, resulting in a decrease in whiteness and variability at the product stage, making it difficult to equalize the quality of the resulting combustion products. Problems arise.
The inventors have completed the present invention as a result of finding out the above problems and intensively studying means for solving the problems.

Next, an example of an embodiment of the production facility of the present invention will be described with reference to the drawings.
〔Overview〕
The production equipment flow capable of obtaining the regenerated particle aggregate of the present invention includes a dehydration process, a drying / combustion process, and a pulverization process. Further, the deinking floss aggregation process or granulation process, and between each process, A classification step or the like may be provided.
FIG. 1 shows a partial configuration example (an example of equipment including a drying / combustion process and a combustion process) of a production facility flow of regenerated particle aggregates. This equipment is equipped with various sensors, and controls the state of combustibles, equipment, and processing speed.
The deinking floss separated from the pulp fiber in the deinking process for producing waste paper pulp (not shown) is dehydrated by a dehydration facility (not shown) through various operations. The material after dehydration preferably has a moisture content of less than 50%, particularly 25 to 45%.
The material 10 after such dehydration is desirably pulverized to a particle size of 40 mm or less by a pulverizer (or pulverizer). The raw material 10 is cut out from the storage tank 12 and charged by a charging machine 15 from one side of the first combustion furnace 14. An exhaust gas chamber 16 is provided on one side of the first combustion furnace 14, and an exhaust chamber 18 is provided on the other side. Hot air is blown from the other side of the first combustion furnace 14 through the discharge chamber 18, charged from the one side, and sequentially transferred to the other side as the first combustion furnace 14 rotates. It is designed to dry and burn.

Here, it is desirable that the hot air blown into the first combustion furnace 14 has an oxygen concentration of 0.2 to 20%. As temperature, 500 to 650 degreeC is desirable. Hot air is blown from a hot air generating furnace 20 provided with a burner 20A.
From the exhaust gas chamber 16, exhaust gas subjected to drying and combustion is sent into the recombustion chamber 22. The fine powder of the combustion material contained in the exhaust gas is discharged from the lower part of the exhaust gas chamber 16 and reused. The exhaust gas is recombusted by the burner in the recombustion chamber 22, precooled by the precooler 24, passed through the heat exchanger 26, and discharged from the chimney 30 by the induction fan 28. Here, after raising the temperature of the outside air, the heat exchanger 26 is sent to the hot air generating furnace 20 and used for the hot air blown from the first combustion furnace 14 to recover the heat of the exhaust gas from the exhaust gas chamber 16. It is like that. The treatment of exhaust gas is effective for removing harmful substances contained in the exhaust gas.
Combustion products that have been dried and burned in the first combustion furnace 14 are charged into the second combustion furnace 32. The particle size of the combusted material to be charged is preferably 20 mm or less. As a heat source in the second combustion furnace 32, it is preferable to adjust by electric power so that temperature control in the second combustion furnace 32 is easy and temperature control in the longitudinal direction is easy. Therefore, the first combustion is indirectly performed by an electric heater. It is desirable that the second combustion furnace 32 be of an external heating type in which the combustion product obtained from the furnace is burned again.

In the second combustion furnace 32, it is desirable to burn so that the oxygen concentration is 5 to 20%. As temperature, 550 degreeC-750 degreeC are desirable. Further, the residence time in the second combustion furnace is preferably 10 minutes to 60 minutes in order to completely burn the remaining carbon.
The regenerated particle aggregate after the completion of combustion is cooled by a cooler 34, and then sorted by a particle size sorter 36 such as a vibration sieve, and adjusted to a target particle size in a pulverization process using a wet pulverizer or the like. The burned product is temporarily stored in the combustion product silo 38 and is sent to the application destination of the pigment and filler.
In addition, although the case where deinking floss was used as a raw material was illustrated, even if it is a combustion thing which used as a raw material what mixed other papermaking sludges, such as papermaking sludge in a papermaking process, with deinking floss as a main raw material Good.

Although the outline has been described above, details and application examples thereof will be described below.
〔material〕
In the used paper pulp manufacturing process, in order to continuously produce used paper pulp of stable quality, used paper is selected and selected, and used paper of a certain quality is used. For this reason, the types, ratios, and amounts of inorganic substances brought into the used paper pulp manufacturing process are basically constant. Moreover, in the manufacturing method for obtaining regenerated particle aggregates, even when plastics such as vinyl and film, which cause fluctuations in unburned materials, are contained in the waste paper, these foreign matters obtain deinking floss. It can be removed before the deinking process. Accordingly, the deinking floss is a raw material for producing regenerated particle aggregates having extremely stable quality as compared with papermaking sludge generated in other processes such as a factory drainage process and a papermaking raw material adjustment process.
The deinking floss referred to in the present invention refers to what is separated from the pulp fiber in the deinking process for removing ink adhering to the used paper in the used paper processing process for producing the used paper pulp.

[Dehydration process]
For further dehydration of the deinking floss, known dehydration means can be used as appropriate. In one example of the present embodiment, the deinking floss is dehydrated by separating water from the deinking floss by a screen serving as a dewatering unit. In the screen, it is preferable that the deinking floss dehydrated to 90% to 97% is sent to, for example, a screw press and further dehydrated to 50% or less.
If the moisture content exceeds 50%, the temperature of the drying / combustion process in the first combustion furnace is lowered, energy loss due to heating increases, and uneven combustion of the raw material is likely to occur, thereby promoting uniform combustion. I want to. Further, there are problems that the moisture in the exhaust gas to be discharged increases, the recombustion treatment efficiency is reduced in dioxin countermeasures, and the load on the exhaust gas treatment facility is increased. In addition, although lowering the moisture content of the raw material facilitates uniform combustion, dehydrating the moisture content of the raw material to less than 25% increases the size of the dehydration equipment and significantly increases the energy of dehydration treatment. Have the problem.
As described above, if the deinking floss is dehydrated in a multi-stage process and abrupt dehydration is avoided, the outflow of the inorganic substance can be suppressed and there is no possibility that the deinking floss floc becomes too hard. In the dehydration treatment, an auxiliary agent for improving the dehydration efficiency such as an aggregating agent for aggregating the deinking floss may be added, but it is preferable to use an aggregating agent that does not contain iron. When iron is contained, it causes a problem of lowering the whiteness of the regenerated particle aggregate due to oxidation of iron.
The deinking process of deinking floss is preferably adjacent to the production process of the regenerated particle aggregate in the present invention in terms of production efficiency. It can also be transported, and it is transported to a fixed amount feeder by a transport means such as a truck or a belt conveyor, and supplied to the drying / combustion process from this constant amount feeder.
In the operation of supplying the raw material 10 after dehydration to the first combustion furnace, it is desirable that the average particle size is preferably adjusted to a particle size of 40 mm or less by a pulverizer (or a pulverizer), more preferably the average particle size. It is preferable to adjust so that the average particle diameter is in the range of 3 to 30 mm, and more preferably in the range of 5 to 25 mm, and it is preferably pulverized so that the ratio of the particle diameter is 50 mm or less is 70 wt% or more. Things are more preferable. In order to achieve a combustion treatment that does not cause a heat change of the calcium carbonate contained in the deinking floss, it is preferable that the particle diameter of the raw material is uniform. However, if the average particle diameter is less than 3 mm, overcombustion tends to occur. This is because an average particle size exceeding 50 has a problem that it is difficult to uniformly burn the raw material core.
In the present invention, the ratio between the average particle size and the particle size was measured using a sample solution sufficiently dispersed by a stirring type disperser.
The particle diameter in each combustion stroke was measured with a metal plate sieve based on JIS Z8801-2: 2000.

[First combustion process] (Drying and combustion process)
The raw material 10 is cut out from the storage tank 12 and supplied to the first combustion furnace. The first combustion furnace has an internal heat kiln furnace system in which a main body is placed horizontally and rotates around a central axis, and is charged from one side of the internal heat kiln furnace 14 by a charging machine 15. The internal heat kiln furnace heating means feeds hot air generated in the hot air generation furnace from the discharge port side of the internal heat kiln furnace so as to counter-flow with the flow of the dehydrated product. An exhaust gas chamber 16 is provided on one side of the internal heat kiln furnace 14, and an exhaust chamber 18 is provided on the other side. Hot air is blown from the other side of the internal heat kiln furnace 14 through the discharge chamber 18, charged from the one side, and sequentially transferred to the other side as the internal heat kiln furnace 14 rotates. It is designed to dry and burn.
That is, in this drying / combustion process, the dehydrated product is dried and burned by a tangible means such as an internal heat kiln furnace in which the main body is placed horizontally and rotates around the central axis, thereby reaching the discharge port from the supply port. Until then, drying and combustion of organic components can be performed gently, pulverization of the combusted matter can be suppressed, and the degree of combustion and particle size of the dehydrated product having various properties such as hard and soft can be controlled stably. Further, the drying can be divided into separate steps and a blow-up type dryer can be inserted.
Here, the hot air blown into the internal heat kiln furnace 14 preferably has an oxygen concentration of 0.2 to 20%, more preferably 1 to 15%, and most preferably 5 to 12%.
Since the oxygen concentration is consumed by the combustion (oxidation) of the raw material, the oxygen concentration varies depending on the state of combustion. If the oxygen concentration is less than 0.2%, it is difficult to achieve sufficient combustion. Oxygen in the combustion furnace is consumed due to the combustion of raw materials and the like, and the oxygen concentration decreases.However, the oxygen concentration is reduced by blowing or exhausting oxygen-containing gas such as air by a hot air generator for combustion. Further, the temperature in the combustion furnace can be finely adjusted by blowing or exhausting the oxygen-containing gas, and the raw material can be burned uniformly without unevenness.
As temperature of a 1st combustion furnace, 500 to 650 degreeC, More preferably, 510 to 620 degreeC, Especially preferably, 530 to 600 degreeC is desirable. In the first combustion furnace, it is preferable that the easily combustible organic matter is gradually burned and burned in a temperature range of 500 ° C. to 650 ° C., and below 500 ° C., the combustion of the organic matter is insufficient. When it exceeds ° C., overcombustion occurs, and calcium oxide is easily generated due to decomposition of calcium carbonate. Further, when the temperature of the hot air exceeds 650 ° C., the drying and combustion progress locally faster than the particle alignment of the burned material having various properties such as hard and soft, so that the unburned particles on the particle surface and inside are not burned. It becomes difficult to make the difference in rate small and uniform.
Hot air is blown from a hot air generating furnace 20 provided with a burner 20A.
From the exhaust gas chamber 16, exhaust gas subjected to drying and combustion is sent into the recombustion chamber 22. The fine powder is discharged from the lower part of the exhaust gas chamber 16 and is mixed with the raw material and reused.
The exhaust gas is recombusted by the burner in the recombustion chamber 22, precooled by the precooler 24, passed through the heat exchanger 26, and discharged from the chimney 30 by the induction fan 28. Here, after raising the temperature of the outside air, the heat exchanger 26 is sent to the hot air generating furnace 20 and is used for hot air blown from the internal heat kiln furnace 14 to recover the heat of the exhaust gas from the exhaust gas chamber 16. It is like that.
The first combustion furnace preferably burns with a residence time of 30 to 90 minutes under the above conditions in order to slowly burn the easily combusted organic substances contained in the deinking floss and suppress the formation of residual carbon. Is preferred. More preferably, 40 minutes to 80 minutes is preferable in terms of combustion of organic matter and production efficiency. Most preferably, a range of 50 minutes to 70 minutes is preferred in order to ensure constant quality. If the combustion time is less than 30 minutes, sufficient combustion is not performed and the proportion of remaining carbon increases. When the burning time exceeds 90 minutes, thermal decomposition of calcium carbonate occurs due to overburning of the raw material, and the resulting regenerated particle aggregate becomes extremely hard.
In particular, it is preferable to dry and burn the unburned rate of the combustion product supplied in the second combustion step of the next step to 2 to 20% by mass, more preferably the unburned rate is set to 2 to 15% by mass. Preferably, the unburned rate is 2 to 10% by mass.
By setting the unburned rate to 2 to 20% by mass, the combustion in the second combustion step can be efficiently performed in a short time, and the hardness is low and the whiteness is 80 by stable heating in the external heating furnace. %, At least 70% or more of high whiteness combustion products can be obtained. If the unburned material is less than 2% by mass, the energy cost in the first combustion furnace is high, and the hardness of the combustion material may be relatively high. There is a case where quality deterioration such as deterioration occurs.

[Second combustion process]
Combustion products that have undergone drying and combustion treatment in the internal heat kiln furnace 14 are loaded into an external heat kiln furnace 32 that corresponds to a second combustion furnace having an external heat jacket 31 that rotates horizontally about the central axis through a transfer channel. Entered.
In this combustion furnace, the combustibles are heated with external heat and gently agitated by friction caused by rotation of the inner wall of the kiln furnace, thereby suppressing particle refinement and more uniformly suppressing the generation of hard substances. While burning the unburned matter.
In the combustion in the second combustion furnace, the residual organic matter that could not be combusted in the first combustion furnace, such as residual carbon, is burned, so that the particle diameter is adjusted to be smaller than the particle diameter of the raw material supplied in the first combustion furnace. It is preferable to use a combustion product. It is preferable to adjust the particle size of the burned product after the drying / combustion step so that the average particle size is 2 to 30 mm, and more preferably, the adjustment is performed so that the average particle size is 2 to 18 mm. It is particularly preferable to perform combustion aggregation so that the average particle diameter is 3 to 15 mm.
If the average particle diameter at the entrance of the second combustion furnace is less than 2 mm, there is a risk of overcombustion, and if the average particle diameter exceeds 30 mm, it is difficult to burn the remaining carbon and combustion does not proceed to the core. This causes a problem that the whiteness of the regenerated particle aggregate is reduced. In order to ensure stable production in the second combustion furnace, it is preferable to adjust the particle size so that the combustion product having a particle size of 1 to 30 mm is 70% or more. Therefore, it is beneficial to the possibility of practical use in terms of making the quality of the regenerated particle aggregate obtained uniform. Furthermore, when the classification is performed after drying as in this embodiment, the combustion product of small-diameter particles can be surely removed, and the processing efficiency is improved.
As an external heat source in the external heat kiln furnace 32, an electric heating type electric kiln furnace in which the temperature control in the external heat kiln furnace 32 is easy and the temperature control in the longitudinal direction is easy is suitable, and the organic matter contained in the raw material It is possible to suppress the generation of hard substances due to overburning of the particles and melting of the regenerated particle constituent substances. Therefore, it is most desirable that the external heat kiln furnace 32 is an electric heater.
By using electricity for external heat, the temperature can be finely adjusted and the internal temperature can be controlled uniformly, and the control of the degree of burning of dehydrated products with various properties, such as hard and soft, and stable particle alignment are possible. It can be carried out.
Furthermore, in the electric kiln furnace, by providing a plurality of electric heaters in the flow direction of the furnace, it is possible to arbitrarily provide a temperature gradient, and it is possible to maintain the temperature of the combustion product for a certain period of time, Residual organic content in the combustion product that has passed through the first combustion furnace, especially residual carbon, can be brought to zero as much as possible without causing uncombusted carbon dioxide decomposition in the second combustion furnace. High whiteness regenerated particle aggregates can be obtained.
In the external heat kiln furnace 32, it is desirable that the oxygen concentration be 5 to 21%, more preferably 10 to 21%, and most preferably 15 to 21%.
When the oxygen concentration in the external heat kiln furnace is less than 5%, there arises a problem that the remaining carbon that is difficult to burn does not burn.
The combustion temperature is preferably 550 to 750 ° C, more preferably 600 to 725 ° C, and particularly preferably 650 to 710 ° C.
As described above, the second combustion furnace is preferably burnt at a higher temperature than the first combustion furnace because it is necessary to burn residual organic matter, particularly residual carbon, that could not be burned in the first combustion furnace. When the combustion temperature is less than 550 ° C., it is difficult to sufficiently burn the residual organic matter, and when the combustion temperature exceeds 750 ° C., the oxidation of calcium carbonate in the combustion product proceeds and the particles become hard. Arise.
The residence time is 10 to 60 minutes, more preferably 15 to 45 minutes, and particularly preferably 20 to 40 minutes. In particular, the remaining carbon must be burnt slowly at a high temperature that does not cause decomposition of calcium carbonate as much as possible. If the residence time is less than 10 minutes, the remaining carbon is burned in a short time and 60 minutes. If it exceeds 1, the problem of decomposition of calcium carbonate occurs.
Furthermore, it is preferable that combustion be performed in a residence time of 10 minutes or more in order to prevent overcombustion and secure productivity in order to ensure stable production of combusted materials.
The particle size of the combustion product discharged from the external heat kiln furnace 32 is preferably adjusted to 20 mm or less, more preferably the average particle size is 5 to 18 mm or less, and most preferably the average particle size is 8 to 15 mm. In addition, setting the ratio of the particle diameter of 20 mm or less to 65% or more is effective for impossibility of reducing the pulverization process as a post-worker.
The regenerated particle agglomerated after the combustion is cooled by the cooler 34, and then a particle having a target particle size is temporarily stored in the combustion product silo 38 by a particle size sorter 36 such as a vibration sieve, so that the pigment and filler It is sent to the use destination.
In addition, although the case where deinking froth was used as a raw material was illustrated, it may be a combustible product obtained by appropriately mixing other papermaking sludge such as papermaking sludge in the papermaking process with deinking floss as the main raw material.

[Crushing process]
The regenerated particle aggregate according to the present invention can be used as a pigment for coating and a filler for internal addition by providing a known dispersion / pulverization step as necessary and finely granulating to a necessary particle size as necessary. .
In the present invention, it is possible to obtain a regenerated particle aggregate in which the content of the hard substance is 2.0% by mass or less, preferably 1.0% or less, and more preferably 0.8% or less. There are also merits that the grinding load can be reduced and the energy cost can be reduced. In one example, after combustion, the obtained particles are pulverized using a dry pulverizer such as a jet mill or a high-speed rotary mill, or a wet pulverizer such as an attritor, a sand grinder, or a ball mill. Regarding the optimum particle size for fillers, pigment applications, etc., the regenerated particle aggregate of this embodiment preferably has an average particle size of 0.1 to 10 μm.
The particle diameter of the regenerated particle aggregate after the pulverization step was measured by a volume average particle diameter using a particle size distribution measuring device (laser type microtrack particle size analyzer: manufactured by Nikkiso).

[Attached process]
In the equipment used to obtain the regenerated particle aggregate of the present invention, it is preferable to classify the particle diameter of the regenerated particle aggregate uniformly in each step in order to obtain more stable quality. The quality can be further stabilized by feeding back coarse particles and fine particles to the previous process.
In addition, it is preferable to granulate the deinked floss that has been subjected to dehydration in the previous stage of the drying process, and it is more preferable to classify the granulated product to make the particle diameter uniform, and the The quality can be further stabilized by feeding back the fine granulated particles to the previous process. In granulation, a known granulation facility can be used, and facilities such as a rotary type, a stirring type and an extrusion type are suitable.
As the raw material of the regenerated particle aggregate of the present invention, it is preferable to remove in advance other than the raw material of the regenerated particle aggregate. For example, a pulper or screen in the previous stage leading to the deinking process of the used paper pulp manufacturing process It is preferable in terms of removal efficiency to remove sand, plastic foreign matter, metal, etc. with a cleaner or the like. In particular, iron contamination is a substance that reduces the whiteness of fine particles due to oxidation, so it is recommended to avoid iron contamination and selectively remove it. Design or lining each process with materials other than iron, It is preferable to prevent iron from being mixed into the system due to abrasion or the like, and to further remove iron selectively by installing a high magnetic material such as a magnet in the drying / classifying equipment.
Thus, deinked floss discharged from the waste paper pulp manufacturing process is used as a main raw material, and the regenerated particle aggregate is obtained by subjecting the main raw material to a dehydration process, a drying process, a baking process, and a pulverization process. In the invention, as the regenerated particle aggregate, a silica-coated regenerated particle aggregate in which the surface of the particles obtained through the above-described steps is further coated with silica can be particularly preferably used.

Silica is further precipitated on the surface of the regenerated particle aggregate to form a silica-coated regenerated particle agglomerate, which is used for paper making as a buffering agent or a bleaching aid by reacting with sodium hydroxide in the used paper processing step in circulation use. This can contribute to the recycling of raw materials and inorganic particles.
In addition, the deinking floss discharged from the used paper processing step used in the present invention has a tendency to increase the content of calcium carbonate with the recent neutral paper making, and the amount of calcium in the regenerated particle aggregate obtained is increased. The ratio also tends to be high. Thus, when the regenerated particle aggregate having a high calcium ratio is internally added to the pulp, the opacity of the paper may be slightly lowered. However, the silica-coated regenerated particle aggregate having silica deposited on the surface is used for papermaking. The function as a regenerated particle aggregate is very high, and the opacity of the backing paper for wallpaper obtained by internally adding the silica-coated regenerated particle aggregate to pulp is improved.
The silica covering the surface of the regenerated particle aggregate can be used without particular limitation as long as it is not naturally produced silica but synthetic silica by some chemical reaction. Specific examples include colloidal silica, silica gel, and anhydrous silica. These synthetic silicas make use of excellent properties such as high specific surface area, high gas adsorbing capacity, fineness, permeability to pores and large adsorbing power, high adhesion, and high oil absorption. It is used in a wide range of fields. Among these, colloidal silica has a shape such as a spherical shape, a chain shape, and an amorphous shape, in which impurities are removed from a silicic acid compound to form an anhydrous silicic acid sol, and the sol is stabilized by adjusting pH and concentration. Amorphous silica. Silica gel is hydrous silicic acid obtained by decomposing sodium silicate with an inorganic acid. Anhydrous silica is obtained by hydrolysis of silicon tetrachloride.

There is no particular limitation on the method for obtaining silica-coated regenerated particle aggregates by precipitating silica on the surface of the regenerated particle aggregates. For example, the following methods can be suitably employed. First, regenerated particle aggregates are added and dispersed in an alkali silicate solution, and after preparing a slurry, while heating and stirring, an acid is added while maintaining the liquid temperature at about 70 to 100 ° C. to produce a silica sol. Subsequently, silica can be deposited on the surface of the regenerated particle aggregate by adjusting the pH of the final reaction solution to a range of 8-11. Silica deposited on the surface of the regenerated particle aggregate in this way reacts at a high temperature with a dilute solution of mineral acid such as sulfuric acid, hydrochloric acid, nitric acid, etc., using alkali silicate (eg, sodium silicate: water glass) as a raw material. And silica sol particles having a particle size of about 10 to 20 nm, which are obtained by hydrolysis reaction and polymerization of silicic acid.
In addition, silica sol fine particles with a particle size of several nanometers, which are generated by adding an acid such as dilute sulfuric acid to an alkali silicate solution such as sodium silicate solution, cover the entire porous surface of the regenerated particle aggregate. The surface of the regenerated particle aggregate is caused by the bond between the silica sol fine particle on the surface of the inorganic fine particle and the silicon, calcium, or aluminum included in the regenerated particle aggregate accompanying the crystal growth of the silica sol fine particle. Silica can be deposited on the substrate. In this case, the pH when adding the acid to the alkali silicate solution is in a neutral to weakly alkaline range, and the pH is preferably adjusted in the range of 8-11. This is because if the acid is added until the pH reaches an acidic condition of less than 7, white carbon may be generated instead of silica sol particles.
The type of the alkali silicate solution is not particularly limited, but a sodium silicate solution (No. 3 water glass) is particularly desirable from the viewpoint of easy availability. The concentration of the alkali silicate solution is such that the silica component in the regenerated particle aggregate decreases and the silica content (SiO _{2) in the} solution does not become difficult to precipitate on the surface of the regenerated particle aggregate. (Converted) is preferably 3% by mass or more, and the silica deposited on the surface of the regenerated particle aggregate becomes white carbon from the form of the silica sol, which impairs the porosity of the regenerated particle aggregate and improves opacity. In order to eliminate the possibility that the effect is insufficient, the silicic acid content (in terms of SiO ₂ ) is preferably 10% by mass or less.

The regenerated particle aggregate thus obtained contains calcium, silicon and aluminum as particle constituents, and these calcium, silicon and aluminum form a composite in the particles. The mass ratio of these calcium, silicon and aluminum in the regenerated particle aggregate (calcium: silicon: aluminum) is determined by X-ray microanalyzer (model number: E-MAX S-2150, Hitachi, Ltd./Horiba, Ltd.). In the elemental analysis using the product, 30 to 82: 9 to 35: 9 to 35, preferably 40 to 82: 9 to 30: 9 to 30, particularly preferably 60 to 82: 9 to 30 in terms of oxide. 20: 9-20. In particular, when the regenerated particle aggregate is a silica-coated regenerated particle aggregate, the mass ratio of calcium, silicon, and aluminum (calcium: silicon: aluminum) is determined by elemental analysis using the X-ray microanalyzer. In terms of oxide, it is 30 to 62:29 to 55: 9 to 35, preferably 30 to 50:35 to 55:15 to 30. At the same time, the total content of calcium, silicon and aluminum in the particle constituents is 90% by mass or more, preferably 94% by mass or more in terms of oxides in the same elemental analysis as described above.
In the case of silica-coated regenerated particles, calcium, silicon, and aluminum are made to have a mass ratio of 10 to 80:10 to 80: 5 to 29 in terms of oxides, so that oil absorption and opacity due to the silica coating effect can be obtained. Can be improved.
Thus, since the regenerated particle aggregate contains calcium, silicon, and aluminum as the particle constituents in terms of oxides in the mass ratio, the specific gravity is light and excessive aqueous solution absorption is suppressed, Dehydration in the dehydration process is good and moisture adjustment in the drying process is easy, as well as reducing the proportion of unburned material in the firing process and reducing the risk of excessive hardness due to sintering. it can.
In order to adjust the mass ratio of calcium, silicon and aluminum in the regenerated particle aggregate within the above range in terms of oxide, for example, it is originally preferable to adjust the raw material composition in the deinking floss, but the drying process or firing In the process, and further in the classification process as necessary, it is also possible to adopt a method of containing a coating floss having a clear origin or an adjustment process floss by spraying or a method of containing incinerator scrubber lime.
For example, to adjust the calcium content in recycled particle aggregates, neutral papermaking wastewater sludge and wastewater sludge from the coated paper manufacturing process, to adjust the silicon content, increase opacity. To adjust the aluminum content of newsprint manufacturing wastewater sludge, which is added in large quantities as an additive, a large amount of papermaking wastewater sludge using acid band such as acid papermaking and clay is used. The drainage sludge from the fine paper making process can be used as appropriate.

The deinking floss contains a large amount of inorganic materials such as calcium carbonate, kaolin, talc, and aluminum sulfate as a papermaking aid as fillers and pigments used for papermaking, and differential thermal thermogravimetric analysis (SII Nanotechnology) Measured by “TG / DTA6200” manufactured by the same company. The same shall apply hereinafter) and X-ray diffraction (measured by “RAD2X” manufactured by Rigaku Corporation. The same shall apply hereinafter). From the analysis, when burning the deinking floss, for example, calcium carbonate (CaCO ₃ ) loses weight at 600 to 750 ° C. and changes to hard and water-soluble calcium oxide (CaO), and clay (Al ₂ For Si ₂ O ₅ (OH) ₄ ), dehydration occurs at around 500 ° C., resulting in a weight reduction, metakaolin, and hard mullite (Al ₂ Si ₂ O ₁₃ ). Further, talc (Mg ₃ Si ₄ O ₁₀ (OH) ₂ ) decreased in weight around 900 ° C. and changed to enstatite (MgSiO ₃ ).
Furthermore, the analysis of the regenerated particles after combustion by X-ray diffraction confirmed the presence of Ca ₂ Al ₂ SiO ₇ (Gelenite) and CaAl ₂ Si ₂ O ₈ (anosite) in the regenerated particles, which were used for papermaking. compared with fillers and pigments, Ca ₂ Al ₂ SiO _{7 (gehlenite), CaAl 2 Si 2 O 8} ( anorthite) is extremely hard (hard material), in the generation of trace amounts, Ya wear and damage to the papermaking equipment It has been found that, when the papermaking system is contaminated and used as a coating pigment, it is a source of wear, damage and streak of coating equipment such as doctors.

Conventionally, Ca ₂ Al ₂ SiO ₇ (Gerlenite) and CaAl ₂ Si ₂ O ₈ (anocite) were expected to be produced at a high temperature exceeding 900 ° C. _It has been found that the production of ₂ Al ₂ SiO ₇ (gerenite) and CaAl ₂ Si ₂ O ₈ (anocite) occurs at a combustion temperature of around 500 ° C., and the production amount increases as the temperature rises.
Furthermore, it was also found that CaAl ₂ Si ₂ O ₈ (anocite) decreases and Ca ₂ Al ₂ SiO ₇ (Gerlenite) tends to increase as the calcium content in oxide conversion in the deinking floss increases. ing.

The used paper used as a raw material of the present invention is due to an increase in the amount of calcium carbonate used as a filler / pigment with the increase in the amount of coated paper with good printing appearance as the neutral papermaking and visualization progress in recent years. , Leading to an increase in the content of calcium carbonate in the deinking floss, resulting in an increase in the production of CaAl ₂ Si ₂ O ₈ (anosite) and Ca ₂ Al ₂ SiO ₇ (gerenite) It is necessary to reduce as much as possible the content of CaAl ₂ Si ₂ O ₈ (anosite), Ca ₂ Al ₂ SiO ₇ (gerenite), so-called hard substances.
In order to reduce the production of hard substances, the dehydrated raw material after dehydration is dried and burned, for example, in a series of first combustion furnaces, and the combustion raw materials burned in the first combustion furnace are again burned. In the facility having the second combustion furnace, at least two stages of combustion operations are required, and the temperature, oxygen concentration, time, and the like can be achieved by carrying out the present invention based on the present invention.
In particular, CaAl ₂ Si ₂ O ₈ (anocite) is likely to be generated by the mixed combustion of calcium oxide and kaolin, and is contained in the deinking floss in the same manner as calcium oxide generated by the overcombustion of calcium carbonate contained in the deinking floss. Since the anorthic substance is easily generated by reaction with kaolin, the weight loss ratio is 5 in the differential thermothermal gravimetric analysis of the regenerated particle aggregate from 25 ° C. to 800 ° C. by the suitable combustion means in the present invention. It is necessary to suppress the generation of so-called calcium oxide as much as possible. In particular, the presence of calcium hydroxide is more likely to generate CaAl ₂ Si ₂ O ₈ (anosite) than calcium oxide, so it is necessary to appropriately adjust the degree of dehydration (moisture) of the raw material and the oxygen concentration in the combustion furnace. There is.

Further, the present inventors have found that the presence of silica contained in the deinking floss promotes the formation of CaAl ₂ Si ₂ O ₈ (anocite) and Ca ₂ Al ₂ SiO ₇ (gerenite). ing. Reducing the silica content as much as possible, for example, suppressing the use of white paper used in newspapers and paper making, relatively low melting points such as CaAl ₂ Si ₂ O ₈ (anosite) and Ca ₂ Al ₂ SiO ₇ (gerenite) It is effective to perform silica coating according to the present invention after forming the regenerated particle aggregate.
In the formation of the preferred regenerated particle aggregate in the present invention, the low melting point minerals CaAl ₂ Si ₂ O ₈ (anosite) and Ca ₂ Al ₂ SiO ₇ (gerenite) are not clearly used in the formation of the aggregate. It is also considered to have a positive effect.

The content of the hard substance can be measured by X-ray diffraction analysis (XRD), and according to the knowledge of the present inventors, as the hard substance, Ca ₂ Al ₂ SiO ₇ (Gelenite), CaAl ₂ Si ₂ O _{8 are used.} A regenerated particle aggregate having an (anosite) content of 2.0% by mass or less, more preferably 1.0% by mass, and most preferably 0.5% by mass or less is suitable. When the content of Ca ₂ Al ₂ SiO ₇ (Gerlenite) and CaAl ₂ Si ₂ O ₈ (anosite) exceeds 2.0% by mass, in the production process of the regenerated particle aggregate, the equipment wear and grinding efficiency If it is used as a paper filler or coating pigment, it may cause a drop in productivity, resulting in wear and damage of paper making tools and soiling in the papermaking system. This causes wear, damage, and streaks in coating equipment.
Further, in the differential thermothermal gravimetric analysis at 25 ° C. to 800 ° C. of the obtained regenerated particle aggregate, the weight loss ratio is preferably 5% (TG) or more, more preferably 7% or more, still more preferably. Is 9% or more. When the weight loss ratio is less than 5% (TG), the calcium carbonate contained in the regenerated particle aggregate is decomposed during combustion and almost changed to hard calcium oxide, and used as a filler or pigment for papermaking. In addition, wear and damage of papermaking tools and dirt in the papermaking system occur, and when used as a pigment for coating, there are problems that cause wear and damage of coating equipment such as doctors and streaks.
In the differential thermothermal gravimetric analysis at 25 ° C. to 800 ° C. of the obtained regenerated particle aggregate, the weight loss ratio is about 35% (TG) at most. There is a risk of lowering the degree.
The deinking floss contains silicon and aluminum in addition to calcium carbonate. When calcium carbonate decomposes during combustion, it reacts with silicon and aluminum to produce high-hardness aluminum calcium silicate, etc. Therefore, it is necessary to burn in a condition where calcium carbonate is not decomposed, for example, in the range of 500 to 750 ° C.
Under such conditions, it is difficult to completely burn the organic compound, and in order to obtain a regenerated particle aggregate having a level of whiteness that can be usefully used for papermaking, it is necessary to burn for a long time. In, the moisture content, oxygen concentration, unburnt ratio, particle size, and average particle size of the raw material after dehydration are adjusted within a predetermined range to shorten the combustion time, and differential thermogravimetric analysis at 25 ° C. to 800 ° C. Thus, a regenerated particle aggregate having a weight loss ratio adjusted to 5% (TG) or more can be obtained.
In differential thermogravimetric analysis from 25 ° C to 800 ° C, when the weight loss ratio is less than 5% (TG), the contents of kaolin, talc, calcium carbonate, titanium dioxide, silica, alumina, etc. contained in the deinking floss This is not preferable because decomposition and sintering proceed and the regenerated particle aggregate obtained by the combustion treatment may require a great deal of energy and time to pulverize to the desired particle size in the present invention.

As a method for adjusting the ratio of the constituents of the regenerated particle aggregate according to the present invention in terms of oxide, the main component is to adjust the raw material composition in the deinking floss, but the drying / combustion process, the combustion process However, it is also possible to make adjustments by means of incorporating a coating floss or adjustment process floss with a clear origin into the process by spraying or the like, or a means of containing incinerator scrubber lime.
For example, using deinked floss as the main raw material, neutral papermaking drainage sludge or drainage sludge from the coated paper manufacturing process is used to adjust calcium in the recycled particle aggregate, and opacity is used to adjust silica. Newspaper production wastewater sludge with a large amount of white carbon added as an improver, papermaking wastewater sludge that uses acid bands such as acidic papermaking to adjust aluminum, and high quality papermaking that uses talc Wastewater sludge in the process can be used.
Further, the regenerated particle aggregate obtained by the present invention has a weight loss (rate) of 50% in the decomposition (change to calcium oxide) of calcium carbonate occurring at around 700 ° C. in the differential thermal analysis using the differential thermothermal gravimetric simultaneous measurement apparatus. As described above, the combustion control of the deinking floss according to the present invention is preferable because the progress of oxidation of the calcium component can be suppressed more accurately and the particles can be prevented from becoming hard.

The Example and comparative example of this invention are shown.
When the quality of the obtained regenerated particle aggregate was examined by changing various factors, the results shown in Table 1 and Table 2 were obtained. The quality was evaluated as follows.
(Rigid substance ratio): X-ray diffraction RAD2X manufactured by Rigaku Denki Co., Ltd. was used. Measurement conditions: Cu-Kα-curved monochromator 40 KV-40 mA, diverging slit 1 mm SS 1 mm RS 0.3 mm, scanning speed 0.8 ° / min, scanning range 2 theta = 7 to 85 degrees, sampling 0.02 degree (unburned rate): After heating the electric muffle furnace to 600 ° C. in advance, the sample was put into a crucible and completely burned in about 3 hours, and the unburned portion was calculated from the change in weight before and after burning.
(Wire wear degree): Measured with a plastic wire wear degree (manufactured by Nippon Filcon, 3 hours) and a slurry concentration of 2% by weight.
(Productivity evaluation): Evaluate raw material dehydration efficiency, productivity, and power required for crushing in 4 stages, ◎ for the most efficient condition, 〇 for good, water efficiency, productivity, pulverization The problem was found as △, and the actual operation difficult as x.
(Quality stability): For each item of whiteness, particle diameter, and production amount at a certain time interval of fine particles obtained by a predetermined method, the degree of fluctuation is measured and ranked in the order of the smallest fluctuation. ◎ from 10th to 20th, △ from 21st to 23rd, and x from below.
(Appearance): The color of the regenerated particle aggregate was compared and judged visually, and was classified into white and gray.
(Differential thermal analysis): SII NanoTechnology Co., Ltd. (model TG / DTA6200) was used, and the measurement conditions were as follows: (1) Heating rate 25-1050 ° C: 20 ° C / min, (2) Supply gas Air (oxygen) (Concentration: about 5 vol%) (3) Supply gas flow rate: about 48 ml / min.

  The present invention is applicable as a regenerated particle aggregate obtained using deinked floss as a main raw material.

  DESCRIPTION OF SYMBOLS 10 ... Raw material, 14 ... Internal heat kiln furnace (1st combustion furnace), 32 ... External heat kiln furnace (2nd combustion furnace).

Claims (2)

A recycled particle aggregate obtained by dehydrating, drying, burning, and pulverizing a raw material mainly made of deinked floss separated from pulp fibers in a deinking process of a used paper processing facility for producing used paper pulp,
Drying and oxidative combustion in an internal heat kiln furnace in which the main body is placed horizontally and rotates around the central axis so that the unburned rate of the combustion product becomes 2 to 20% by mass at a combustion temperature of 500 to 650 ° C. and a residence time of 30 to 90 minutes A first combustion process, and a second combustion process in which combustion is performed again at a combustion temperature of 550 to 750 ° C. and a combustion time of 10 to 60 minutes higher than the combustion temperature in the first combustion process. Obtained through the process,
The raw material supplied to the internal heat kiln furnace is adjusted so that the moisture content is 25 to 50%, the average particle diameter is 3 to 40 mm, and the ratio of the particle diameter is 50 mm or less is 70% by weight or more,
The regenerated particle aggregate has a weight loss ratio of 5% (TG) or more, a total content of the following hard substances of 2.0% by mass or less, and whiteness in a differential thermothermal gravimetric analysis at 25 ° C. to 800 ° C. Is 70% or more,
A regenerated particle aggregate characterized by that.
Hard materials: Ca ₂ Al ₂ SiO ₇ , CaAl ₂ Si ₂ O ₈ The surface of the regenerated particle aggregate is coated with silica,
The mass ratios of calcium, silicon, and aluminum are converted to oxides by elemental analysis using an X-ray microanalyzer, and 30 to 82: 9 to 35: 9 to 35 in the state where the silica is not coated. 30-62: 29-55: 9-35 in the coated state,
1 Symbol mounting playback particle aggregate claims.

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