JP2012024706A - Method for production of regenerated particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for production of regenerated particles capable of stably obtaining the regenerated particle which has a low content of hard materials, is easy to slurry, has high whiteness and is excellent in energy efficiency.SOLUTION: The method for production of regenerated particles includes dehydrating and heat-treating a material 10 to be treated. The heat treatment is performed by dividing into: a drying method 60 for drying the material 10 after dehydration; a first heat treatment method 42 for heat-treating the dried material 10; a second heat treatment method 14 for heat-treating the material 10 after the first heat treatment at a temperature exceeding that of the first heat treatment; and a third heat treatment method 32 for heat-treating the material 10 after the second heat treatment at a temperature exceeding that of the second heat treatment. An external heating jacket 43 is provided on the outer surface of a furnace body for the first heat treatment method 42, and hot air is supplied into the external heating jacket 43 to form an external heating furnace. An exhaust gas G7 discharged from the external heating jacket 43 is blown in the furnace body.

Description

  The present invention relates to a method for producing regenerated particles by dehydrating and heat-treating an object to be treated mainly using paper sludge.

  At present, various methods have been proposed for producing recycled particles from paper sludge. For example, there are a method of carbonizing and burning paper sludge, a method of burning under specific conditions without carbonization, and the like. In addition, these methods involve dry oxidation (so-called combustion) of papermaking sludge, but a method combining dry oxidation and wet oxidation has also been proposed. Furthermore, a primary combustion step for burning and removing easily combustible organic substances in the paper sludge under an excess air atmosphere at a combustion temperature of 650 ° C. or less; and a non-combustibility in the paper sludge at a combustion temperature of 700 ° C. to 850 ° C. under an excess air atmosphere There is also a proposal that high-quality combustion ash having high whiteness can be obtained efficiently through a two-stage combustion process including a secondary combustion process for removing organic substances by combustion (see Patent Document 1). .

However, these conventional manufacturing methods have the following problems.
(1) The raw material turns yellow due to high-temperature combustion, resulting in a decrease in whiteness. (2) Hard materials such as gelenite (for example, see Patent Document 2) are easily generated by melting the raw material, and the degree of wire wear in the papermaking equipment is increased. (3) Since aggregates are formed by melting the raw materials, the pulverization energy in the subsequent pulverization step increases, and the processing efficiency decreases. (4) Since the surface of the raw material is melted by being exposed to a high temperature, the combustion reaction (oxidation reaction) does not proceed to the inside of the raw material, and organic matter (carbon) remains. As a result, the whiteness is reduced. (5) It solidifies when the obtained regenerated particles are slurried.

  Paper sludge mixed with sludge discharged from various processes contains fine inorganic fine particles used as raw materials for recycled particles, and is often used for fine fibers and coated paper that are difficult to use as waste paper pulp. Since it contains a lot of organic polymer latex and ink components applied by printing, the papermaking sludge itself burns (oxidizes) itself in the combustion process. Therefore, when regenerated particles are produced using papermaking sludge in general as a raw material, heat generation more than heat treatment occurs, causing overburning of the raw material. Therefore, overburning due to the heat generation is prevented, and preferably, it is sought whether the heat generation can be effectively used as energy.

JP 2008-207173 A JP 2008-190049 A

  The main problem to be solved by the present invention is that the content of a hard substance suitable for making a papermaking filler or a coating pigment is low, easy to slurry, and regenerated particles with high whiteness are stably produced. An object of the present invention is to provide a method for producing regenerated particles that can be obtained and is excellent in energy efficiency.

The present invention that has solved this problem is as follows.
[Invention of Claim 1]
A process for producing regenerated particles by dehydrating and heat-treating an object to be processed using papermaking sludge as a main raw material,
The heat treatment includes a drying means for drying the dehydrated article, a first heat treatment means for heat treating the article dried by the drying means, and a treatment heat treated by the first heat treatment means. A second heat treatment means for heat-treating the product at a temperature exceeding the first heat treatment temperature; and a third heat treatment for treating an object heat-treated at the second heat treatment means at a temperature exceeding the second heat treatment temperature. Heat treatment means, and divided into at least four means,
At least one of the first heat treatment means and the second heat treatment means is an external heat furnace in which an external heat jacket is provided on the outer surface of the furnace body, and hot air is supplied into the external heat jacket,
Injecting exhaust gas discharged from the outer heat jacket into the furnace body,
A method for producing regenerated particles.

(Function and effect)
In the first and second heat treatment means, the object to be processed contains a high calorific value component, and the risk of ignition is high. Therefore, it is preferable to have a low oxygen concentration, and an external heating furnace is suitable. Further, when exhaust gas is blown into the furnace main body, the temperature difference generated between the inner surface of the furnace main body and the shaft center portion is eliminated, and exhaust of the pyrolysis gas that causes ignition is promoted. Further, since the exhaust gas is discharged from the external heat jacket and is also used as an external heat source, the heat energy is effectively used. In addition, although the to-be-processed object may ignite if the gas supplied in a furnace main body is high temperature, if the exhaust gas after utilizing as an external heat source is utilized, the danger of the said ignition will be prevented.

[Invention of Claim 2]
The method for producing regenerated particles according to claim 1, wherein exhaust gas discharged from the furnace body or from the furnace body of another heat treatment means is used as hot air supplied into the outer heat jacket.

(Function and effect)
The exhaust gas discharged from the furnace body has a reduced oxygen concentration. Therefore, when the exhaust gas is supplied into the outer heat jacket and the exhaust gas discharged from the outer heat jacket is supplied into the furnace body, the object to be processed is ignited due to oxygen in the gas supplied into the furnace body. Is prevented.

[Invention of Claim 3]
Both the first heat treatment means and the second heat treatment means are provided as an external heat furnace in which an external heat jacket is provided on the outer surface of the furnace body, and hot air is supplied into the external heat jacket. While the heat treatment means is an internal heating furnace in which hot air is blown into the furnace body,
Supplying the exhaust gas discharged from the furnace body of the third heat treatment means into the outer heat jacket of the second heat treatment means,
Supplying a part of the exhaust gas discharged from the furnace body of the second heat treatment means into the outer heat jacket of the first heat treatment means;
Exhaust gas discharged from the furnace body of the first heat treatment means, the remainder of the exhaust gas discharged from the furnace body of the second heat treatment means, and an external heat jacket of the second heat treatment means Using exhaust gas as a heat source for the drying means,
Injecting exhaust gas discharged from the external heat jacket of the first heat treatment means into the furnace body of the first heat treatment means,
The method for producing regenerated particles according to claim 1 or 2.

(Function and effect)
Part of the exhaust gas discharged from the furnace body of the second heat treatment means is supplied into the outer heat jacket of the first heat treatment means, and the exhaust gas discharged from the outer heat jacket is supplied to the furnace body of the first heat treatment means. When blown in, the first heat treatment means can obtain the same effects as those of the first or second aspect of the invention. Moreover, since the second heat treatment means is heat-treated at a temperature exceeding the heat treatment temperature in the first heat treatment means, the exhaust gas supplied into the outer heat jacket of the first heat treatment means is supplied to the furnace body of the second heat treatment means. According to the configuration of the exhaust gas discharged from the inside, it is not necessary to heat the exhaust gas supplied into the external heat jacket of the first heat treatment means, or the heating can be weakened, and the thermal energy efficiency is improved. .

[Invention of Claim 4]
Injecting exhaust gas discharged from the external heat jacket of the second heat treatment means into the furnace body of the second heat treatment means,
The temperature of the outer surface of the furnace body of the first heat treatment means is 250 to 400 ° C., the temperature of the outer surface of the furnace body of the second heat treatment means is 360 to 550 ° C., and the temperature inside the furnace body of the third heat treatment means Becomes 550-780 ° C., the temperature of the exhaust gas blown into the furnace body of the first heat treatment means is 150-350 ° C., and the temperature of the exhaust gas blown into the furnace body of the second heat treatment means becomes 260-450 ° C. To control,
The method for producing regenerated particles according to claim 3.

(Function and effect)
When exhaust gas discharged from the external heat jacket of the second heat treatment means is blown into the furnace body of the second heat treatment means, the second heat treatment means is the same as the invention according to claim 1 or claim 2. The following effects can be obtained. At this time, if the temperature range is controlled to be within the above range, regenerated particles suitable for making a papermaking filler or a coating pigment can be more reliably and efficiently obtained.

  According to the present invention, it is possible to stably obtain regenerated particles having a low content of a hard substance suitable for making a paper filler or a coating pigment, easy to slurry, and having high whiteness, and energy. This is a method for producing regenerated particles with excellent efficiency.

It is a manufacturing equipment flow figure of regenerated particles.

Next, the form for implementing this invention is demonstrated.
[Positioning of the present invention]
The organic matter contained in paper sludge varies in a variety of ways depending on the source, papermaking varieties in the paper mill, periodic repairs, production fluctuations, etc., and the quality fluctuations lead to fluctuations in the calorific value of the paper sludge. The problem that the quality of the regenerated particles that are finally obtained decreases, for example, the hard material content increases and the papermaking equipment is easily worn, it becomes difficult to make a uniform slurry, the whiteness is low Problems such as non-uniformity occur.

  Therefore, the present inventors have made various studies, and as a result, a heat treatment of the object to be processed using papermaking sludge as a main raw material, a drying means for drying the object to be processed after dehydration, and a dried object to be processed. A first heat treatment means for heat treatment; a second heat treatment means for heat-treating an object heat-treated by the first heat treatment means at a temperature exceeding the first heat treatment temperature; and a heat treatment by the second heat treatment means. It has been found that the problem of quality degradation of regenerated particles can be solved by performing the processed object separately from the third heat treatment means for heat treatment at a temperature exceeding the second heat treatment temperature.

  Further, on the premise of this, the first heat treatment means and the second heat treatment means are provided as an external heat furnace in which an external heat jacket is provided on the outer surface of the furnace body and hot air is supplied into the external heat jacket. It has been found that by blowing the exhaust gas discharged from the outer heat jacket into the furnace body, the problem of the quality deterioration of the regenerated particles can be solved more reliably and the energy efficiency is excellent.

  In this regard, the advantage of dividing the heat treatment into first to third heat treatments in addition to drying is as follows. That is, papermaking sludge contains various organic substances. Among these organic substances, acrylic organic substances having a calorific value peak around 220 ° C. derived from paper, cellulose having a calorific value peak around 320 ° C., and around 420 ° C. A styrenic organic component having a calorific value peak is contained, and has a calorific value of 1000 to 2000 cal / g, for example. In the conventional method for producing regenerated particles, measures have been taken to burn and remove these organic components together with other organic components. However, the inventors of the present invention indicate that each of the above organic substances is a substance having a high calorific value with a peak calorific value in the vicinity of the above temperature, and is ignited when burning an organic component thermally decomposed at 200 to 300 ° C.・ Overcombustion occurs, combustion control becomes difficult, and not only a decrease in whiteness but also the generation of hard substances is found. First, in the first heat treatment, predetermined high calorific value components (acrylic organic matter and cellulose) ) Was removed from the object to be treated by heat treatment, and it was found that overburning can be suppressed and the formation of hard substances can be suppressed.

  In addition, in the conventional method for producing regenerated particles, the moisture content is less than 40% in order to efficiently burn fine fibers in the material to be processed, latex that is an organic polymer, ink components applied by printing, and the like. Measures were taken to dehydrate and dry and heat treat at high temperatures. On the other hand, in the first heat treatment, if the organic matter that is thermally decomposed and volatile-evaporated at 200 to 300 ° C. in the first heat treatment is pyrolyzed and gasified, Styrenic organic substances can be pyrolyzed and gasified, and overburning and pulverization of the object to be treated are suppressed. Moreover, in the third heat treatment, organic substances including residual carbon and the like in the object to be treated can be efficiently removed by heat treatment, and generation of hard substances caused by overcombustion can be suppressed. Furthermore, since the ignition temperature of the pyrolysis gas of cellulose is lower than the pyrolysis temperature of styrene, it is preferable that cellulose is thermally decomposed and removed in the first heat treatment, and styrene is thermally decomposed in the second heat treatment.

On the other hand, in the present invention, it is preferable to use a kiln furnace in each heat treatment means except the drying means. The reason for this is as follows.
In the stalker furnace (fixed bed), it is difficult to adjust the degree of combustion, and the regenerated particles become non-uniform, and dust falls from the clearance between the grate. Since air is blown up from below the object to be treated through the grate and burned, calcium carbonate or the like becomes fly ash and is sent to the exhaust gas facility together with the exhaust gas, resulting in a decrease in yield. Since the stoker (stepped shape) is heat-treated while passing the object to be treated with a predetermined width, the stirring is insufficient and the heat treatment varies in the width direction.
The fluidized bed furnace has a problem that since a fluid medium such as silica sand is mixed in the object to be treated, the quality is deteriorated and uniform stirring cannot be performed. The dredged sand and the like are separated from the object to be treated, and the dredged sand and the like are returned to the furnace, and only the object to be treated is taken out. Since the heat treatment is performed in a floating state, it is difficult to adjust the degree of heat treatment, resulting in quality variations. Since the object to be processed is pulverized by friction and collision with high hardness silica sand and the like and is discharged as fly ash, the yield decreases.
In the cyclone furnace, the object to be processed passes through the furnace in an instant, so that the organic matter cannot be sufficiently heat-treated, and the whiteness is lowered. In addition, because of air blowing, fine particles are not separated by the cyclone, and the exhaust gas is transferred to the exhaust gas treatment process together with the exhaust gas, resulting in a decrease in yield.
From the above, in each heat treatment means except the drying means, a kiln furnace was selected as a suitable heat treatment means.

[Embodiments of the present invention]
Next, an embodiment of the present invention will be described with reference to FIG. 1 showing a configuration example of a production facility flow of regenerated particles. Note that the present embodiment also has a feature in the use of exhaust gas as a heat source. This point will be described in succession at the end.

(Processed object)
The workpiece 10 of this embodiment uses papermaking sludge as the main raw material (50% by mass or more). The paper sludge is, for example, a fiber component such as pulp, an organic substance such as starch or synthetic resin adhesive, an inorganic substance such as a filler or a coating pigment that has been transferred to waste water, a pulping process, etc. It consists of lignin and fine fibers that are generated, fillers and printing inks derived from waste paper, and excess sludge generated from biological wastewater treatment processes. Further, for example, it may contain a solid component or the like derived from a deinking process for removing printing ink or the like in a used paper pulp manufacturing process or a cleaning process for recovering and cleaning papermaking raw materials.

  However, in the used paper pulp manufacturing process, in order to continuously produce a used paper pulp having a stable quality, a used paper of a certain quality that has been selected and selected is used. Therefore, the types, ratios, amounts, etc. of inorganic substances brought into the waste paper pulp manufacturing process are basically constant. Moreover, even if waste paper contains plastics such as vinyl and film, which cause fluctuations in the unburned rate, these are used for the pulper, screen, cleaner, etc. before the deinking process where deinking floss is generated. Is removed. Therefore, compared with papermaking sludge generated in other processes such as a factory drainage process and a papermaking raw material preparation process, the deinking floss becomes a raw material of the object to be processed 10 for producing regenerated particles with extremely stable quality. .

(Dehydration process)
The workpiece 10 is dehydrated using, for example, a known dehydrator. In the present embodiment, the workpiece 10 is dehydrated to a moisture content of 65 to 90% by, for example, a screen, and then to a moisture content of 30 to 60%, preferably 30 to 50%, more preferably 35 by a screw press. Dehydrate to ~ 45%. The moisture content here is a constant temperature dryer, the sample (object to be processed) is allowed to stand in the dryer, and when the mass fluctuation is no longer recognized by holding at about 105 ° C. for 6 hours or more, the weight after drying is defined as It is a value calculated from the mass measurement result before and after drying by the following formula.
Moisture content (%) = (mass before drying−mass after drying) ÷ mass before drying × 100

  When the moisture content of the processed material 10 after dehydration exceeds 60%, energy loss for drying in the drying device 60 increases. And since the fluctuation | variation of the drying temperature in the drying apparatus 60 becomes large, there exists a possibility that drying nonuniformity may arise. In particular, when an airflow drying device is used as the drying device 60, the object to be processed 10 is discharged from the drying device 60 before the drying proceeds sufficiently, and thus the object to be processed 10 may not be sufficiently unraveled. This may cause energy loss in the heat treatment furnace 42 and cause of heat treatment fluctuation. On the other hand, if the dewatering is performed until the moisture content of the processed object 10 after dehydration becomes less than 30%, the processed object 10 becomes solidified due to high compression. Even if it exists, there exists a possibility that the to-be-processed object 10 may not be understood. In addition, if the object to be processed 10 is dehydrated in multiple stages as in this embodiment and abrupt dehydration is avoided, the outflow of the inorganic substance can be suppressed, and the floc of the object to be processed 10 is prevented from becoming too hard. can do.

(Unraveling process)
The to-be-processed object 10 after dehydration is cut out from the storage tank 12, sent to a drying process, and dried. However, prior to this drying, the ratio of the particle diameter of 50 mm or more is preferably 30 to 70% by mass, preferably 40 to 70% by mass, for example, by a stirrer or a mechanical roll. More preferably, it is preferable to loosen it so as to be 50 to 70% by mass. Here, “the ratio of the particle diameter of 50 mm or more” is the mass ratio of the object to be processed that has not passed through the sieve having a 50 mm eye hole when the mass of the entire object to be processed is 100. In this measurement, a metal plate sieve is used based on JIS Z 8801-2: 2000.

  It is preferable that the object to be processed 10 at the time of drying does not have an object to be processed having a large particle diameter. Specifically, the ratio of the particle diameter of 50 mm or more is preferably 70% by mass or less. However, in this embodiment, as a particularly preferable embodiment, a rotary kiln is not used in the drying step, and an airflow drying device is used. Therefore, it is not necessary to unravel the workpiece 10 excessively, and the ratio of the particle diameter of 50 mm or more is less than 30% by mass. Even if it is not solved until it becomes, a homogeneous product can be obtained.

  In addition, when the to-be-processed object 10 is already "the ratio with a particle diameter of 50 mm or more is 70 mass% or less" after spin-drying | dehydration, an open process can also be skipped. In this case, the to-be-processed object 10 after dehydration can be sent to the drying process as it is as the to-be-processed object 10 having a “particle diameter of 50 mm or more is 70% or less”.

(Drying process)
After the dehydration, the object to be processed 10 is properly disassembled and then supplied to the drying device 60 serving as a drying means. The form of this drying apparatus 60 is not specifically limited, For example, well-known drying apparatuses, such as a stalker furnace, a fluidized bed furnace, a cyclone furnace, a kiln furnace, can be used. However, in this embodiment, as the drying device 60, an “airflow drying device” that dries the workpiece 10 with a hot airflow is used. When the airflow drying apparatus is used, the object to be processed 10 is dried at the same time and is uniformly solved under a large dispersion force without applying a compressive force. Heat treatment is performed uniformly and reliably, and regenerated particles with uniform quality can be stably produced.

  In this regard, it may be difficult to unravel the object to be processed uniformly until it becomes a state suitable for the subsequent heat treatment prior to drying. In addition, if the material to be processed is unraveled prior to drying, it is necessary to increase the dewatering rate. However, if the dewatering rate is increased, the material to be processed is highly compressed, and the drying efficiency of the material to be processed is partially increased. There is a risk of lowering, and there is a risk of non-uniform drying treatment and thus non-uniform product. On the other hand, if the object to be processed is unraveled after drying, the object to be processed in a non-uniform state is dried. Therefore, drying may not be performed uniformly and heat treatment may not be performed uniformly.

  As the airflow drying device, for example, a well-known device such as a trade name “Kudakera” manufactured by Shin Nippon Kaihe Heavy Industries Co., Ltd., an improved device thereof, or the like can be used.

  The airflow type drying apparatus 60 is supplied with the dehydrated object 10 from the storage tank 12 and blows exhaust gas (mixed gas) G as a heat source from a first exhaust gas channel R1 described later. The object to be processed 10 supplied with the hot air flow generated by the exhaust gas G is accompanied. Therefore, for example, by controlling the hot air flow by adjusting the temperature, flow rate, flow rate, etc. of the exhaust gas G, it is possible to adjust the dry state and the unfolded state of the workpiece 10.

  The control of the exhaust gas G is performed so that the workpiece 10 having a particle diameter of 50 mm or more does not exist and the average particle diameter of the workpiece 10 is 1 to 7 mm, preferably 1 to 5 mm. More preferably, it is suitable to be 1 to 3 mm. Here, the “average particle diameter” of the object to be processed 10 is obtained by sieving with a sieve having different eye holes, measuring the mass of the object to be processed after each sieving, and the total value of the measured values is the entire value. 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. The “ratio of particle diameter of 50 mm or more” of the workpiece 10 is as described above.

  When the average particle diameter of the workpiece 10 is less than 1 mm, excessive heat treatment tends to occur in the first heat treatment. On the other hand, when the average particle diameter of the object to be processed 10 exceeds 7 mm or the object to be processed 10 having a particle diameter of 50 mm or more is present, it is difficult to uniformly heat-treat the object 10 from the surface portion to the core portion.

  In this embodiment, the temperature of the hot airflow is not particularly limited, but the temperature of the exhaust gas G (when hot air or diluted air is blown into the drying device 60 separately from the exhaust gas G, the average temperature of all gases. The temperature of the outflow gas (exhaust gas) G6 from the drying device 60 is preferably controlled to be 500 ° C. or less. It is more preferable to control the temperature of the inflow gas G6 from the drying device 60 to be 400 ° C. or lower and the temperature of the inflow gas G to be 300 to 400 ° C. It is particularly preferable to control the temperature of the outflow gas G6 from 60 to be 300 ° C. or lower. According to this embodiment, the moisture content of the workpiece 10 is preferably 0 to 5%, more preferably 0 to 3%, and particularly preferably 0 to 1% in only 1 to 3 seconds. Can be dried. Moreover, since this drying is performed while the object to be processed 10 is unwound by the hot air current, the moisture content is uniform throughout the object to be processed 10. In addition, since the object to be processed 10 is discharged from the drying device 60 at the next moment when moisture is evaporated, there is no possibility of unintentional heat treatment such as thermal decomposition and combustion of organic substances.

  The effluent gas G6 discharged from the drying device 60 is constituted by appropriately combining gas treatment devices such as a deodorizing device and a bag filter after the object 10 mixed in the exhaust gas G6 is collected by a dust collecting means such as a cyclone. It passes through the gas treatment facility 22 and is discharged from the chimney 30. Since the temperature of the exhaust gas G6 is lowered due to the evaporation of moisture from the workpiece 10 in the drying device 60, a heat exchanger provided in a normal exhaust gas treatment facility can be omitted. Further, as will be described later, the exhaust gas G supplied to the drying device 60 is mainly produced by combusting an organic pyrolysis gas at a sufficiently high temperature. Therefore, the exhaust gas G is not provided with a gas treatment device such as a recombustion furnace. The harmful substances in G can be sufficiently removed. Even if a recombustion furnace is provided, the workpiece 10 burned in the recombustion furnace cannot be used as a raw material because it is hard and has low whiteness due to overcombustion.

(First heat treatment step)
The to-be-processed object 10 after drying is sent to a 1st heat treatment process, and is charged into the 1st heat treatment furnace 42 which is a 1st heat treatment means by the charging machine etc. which are not shown in figure. As the first heat treatment furnace 42, an external heat kiln furnace in which the furnace body is placed horizontally and rotates around the central axis is used. Since the workpiece 10 supplied to the first heat treatment furnace 42 contains a high calorific value component such as an acrylic organic material or cellulose, the interior of the furnace body is reduced from the viewpoint of preventing ignition of the workpiece 10. The oxygen concentration is preferably used, and an external heating furnace is used. In addition, when drying (evaporation of water) and thermal decomposition / combustion of the workpiece 10 are performed in the same apparatus (furnace), different heat treatments are continuously performed, and the control of the heat treatment temperature is complicated. Become. However, if the workpiece 10 is dried prior to the first heat treatment, it is easy to control the heat treatment temperature.

  In the first heat treatment furnace 42, an external heat jacket 43 is provided on the outer surface of the furnace body. The outer heat jacket 43 is supplied with exhaust gas G2 from a second exhaust gas flow path R2 described later, and the workpiece 10 deposited on the inner surface of the furnace body is indirectly heated by indirect heating by the exhaust gas G2. (External heat type) If only the production of regenerated particles is intended, an electric heater or the like can be used instead of supplying the exhaust gas G2, but the configuration according to the present embodiment is preferable from the viewpoint of effective use of the exhaust gas G2 (energy). It is.

  In relation to the heat treatment divided into at least four heat treatment means, the first heat treatment furnace 42 is preferably heated so that the temperature of the outer surface of the furnace body becomes 250 to 400 ° C., 300 to 360. It is more preferable to heat so that it may become degreeC, and it is especially preferable to heat so that it may become 310-350 degreeC. When the temperature of the outer surface of the furnace main body is 250 ° C. or higher, the thermal decomposition and volatilization of the acrylic organic matter and cellulose in the workpiece 10 are reliably performed. In addition, since the thermal decomposition and volatilization of the acrylic organic material and cellulose are reliably performed, the heat treatment control in the second heat treatment furnace 14 and the third heat treatment furnace 32 becomes easy, and the generation of carbides that cause a decrease in whiteness is generated. Moreover, the production | generation of the hard substance by overcombustion can be suppressed. Furthermore, the thermal decomposition and volatilization of the acrylic organic material and cellulose are performed reliably, so that the organic material such as the styrene organic material and the residual carbon is gently heat-treated in the second heat treatment furnace 14 and the third heat treatment furnace 32. And the generation of residual carbon can be suppressed. However, if the temperature of the outer surface of the furnace body exceeds 400 ° C., the pyrolysis gas in the furnace body may ignite, the heat treatment energy in the second heat treatment furnace 14 increases, and further, the flame retardant carbon Is likely to be produced, and there is a possibility that it is impossible to stably obtain regenerated particles having characteristics required as a filler or pigment for papermaking. In the case where the drying process is not provided before the first heat treatment process, it is necessary to set the heat treatment temperature higher in order to dry the workpiece 10 in this heat treatment process, and the above risks are involved. Will accompany.

  As described above, the first heat treatment furnace 42 is an external heat furnace, but in this embodiment, the exhaust gas G7 discharged from the external heat jacket 43 is passed through the exhaust gas flow path R7 and the furnace main body of the first heat treatment furnace 42 is concerned. Blow in. This blowing eliminates the temperature difference between the inner surface of the furnace body and the shaft center, and promotes exhaust of pyrolysis gas that causes ignition from the furnace body. Further, the exhaust gas G7 is exhaust gas discharged from the external heat jacket 43, and is used as an external heat source, so that the energy is effectively used.

  The exhaust gas G7 is blown into the furnace body at a temperature lower than the temperature of the outer surface of the furnace body, preferably 150 to 350 ° C, more preferably 175 to 325 ° C, and particularly preferably 200 to 300 ° C. If the temperature of the exhaust gas G7 exceeds 350 ° C., the workpiece 10 in the furnace body may ignite. On the other hand, if the temperature of the exhaust gas G7 is lower than 150 ° C., the temperature difference that occurs between the inner surface of the furnace body and the shaft center portion is not eliminated, and there is a possibility that it will spread.

  The oxygen concentration of the exhaust gas G7 is adjusted to 1.0 to 20.0%, preferably 2.0 to 18.0%, more preferably 4.0 to 18.0%, and the furnace body of the first heat treatment furnace 42 The oxygen concentration of exhaust gas (outflow gas) G1 discharged from the inside is 0.1 to 20.0%, preferably 1.0 to 17.0%, more preferably 3.0 to 15.0%. It is preferable to manage. Here, the oxygen concentration is a value obtained by measuring the oxygen concentration of a measurement sample sampled from each measurement region with an automatic oxygen concentration measurement apparatus (model number: ENDA-5250, manufactured by Horiba Seisakusho).

  From the viewpoint of preventing excessive heat treatment due to ignition of the workpiece 10 or the like, it is preferable that the oxygen concentration is low, the oxygen concentration of the exhaust gas G7 is adjusted to 20.0% or less, and the outflow gas G1 It is preferable to manage the oxygen concentration to be 20.0% or less. However, if the oxygen concentration of the exhaust gas is less than 1.0% or the oxygen concentration of the effluent gas G1 is less than 0.1%, the carbonization of the organic matter is promoted. It may be difficult to obtain a degree. In addition, the heat treatment of acrylic organic matter, cellulose, or the like does not proceed sufficiently, and it may be difficult to adjust the rate of decrease in the calorific value within a predetermined range. In addition, since the carbide has a characteristic that once it starts to burn, it becomes a high temperature and the temperature cannot be controlled. Therefore, if the carbonization of the organic material is promoted, the temperature control becomes difficult in any heat treatment.

  Note that the oxygen concentration in the furnace body of the first heat treatment furnace 42 may be consumed and fluctuated during the heat treatment of acrylic organic matter, cellulose, or the like, so that the oxygen concentration of the exhaust gas G7 is adjusted as in this embodiment. It is preferable to control the oxygen concentration of the effluent gas G1. However, by performing such adjustment and control, the oxygen concentration is usually 0.1 to 20.0%, preferably 1.0 to 17.0%, more preferably 3 in many regions within the furnace body. Adjusted to 0.0-15.0%.

  In the first heat treatment furnace 42, heat treatment is performed so that the calorific value of the workpiece 10 is reduced by 20 to 90%, preferably 50 to 80%, more preferably 50 to 70%. . When the rate of decrease in the calorific value is 90% or less, excessive heat treatment is suppressed, and generation of hard substances is suppressed. In this respect, a decrease in the calorific value exceeding 90% means that even the styrene-based organic matter in the object to be treated 10 is pyrolyzed, so that pyrolyzed gas such as cellulose can be ignited in the furnace body. It means that it is in a state (that is, a high temperature state). On the other hand, if the rate of decrease in the calorific value is less than 20%, acrylic organic matter that is a high calorific value component in the workpiece 10 remains, and the fluctuation of the heat treatment temperature in the second heat treatment furnace 14 becomes large. There is a fear. Here, the rate of decrease in the amount of heat generated was a comparison between the amount of heat generated by the workpiece 10 supplied to the first heat treatment furnace 42 and the amount of heat generated by the workpiece 10 discharged from the first heat treatment furnace 42. Value. This calorific value is a value measured using a calorimeter (Nanken digital calorimeter, manufactured by Yoshida Seisakusho).

  In the first heat treatment furnace 42, when the heat generation amount is reduced by 20 to 90% and the heat generation amount is less than 1000 cal / g, preferably 300 to 500 cal / g, the furnace body in the second heat treatment furnace 14 It becomes easy to suppress the fluctuation range of the internal temperature within the range of 10 to 40 ° C., which is useful for homogenizing the obtained regenerated particles. In this regard, if the fluctuation range of the furnace body temperature exceeds 40 ° C., the obtained regenerated particles may have variations such as hard and soft, and variations in whiteness. On the other hand, it is not realistic to suppress the fluctuation range of the furnace body temperature to less than 10 ° C.

  In the first heat treatment furnace 42, the unburned rate of the workpiece 10 is 13 to 30% by mass, preferably 14 to 26% by mass, and more preferably 15 to 23% by mass. Thus, it is preferable to perform the heat treatment. Here, the unburned rate is a value obtained by measuring a weight loss ratio when burned for 2 hours in an electric furnace whose temperature is adjusted to about 600 ° C. By performing the heat treatment so that the unburned rate becomes 30% by mass or less, the heat treatment in the second heat treatment furnace 14 can be performed slowly. However, if the heat treatment is performed until the unburned rate becomes less than 13% by mass, the energy cost in the first heat treatment furnace 42 increases.

  In the first heat treatment furnace 42, the residence time of the workpiece 10 is 30 to 120 minutes, preferably 45 to 105 minutes, more preferably 60 to 90 minutes. By setting the residence time to 30 minutes or longer, the acrylic organic matter and cellulose contained in the object to be processed 10 are slowly pyrolyzed, and the generation of residual carbon is suppressed. In this regard, if the residence time is less than 30 minutes, sufficient heat treatment is not performed, and the proportion of residual carbon increases. On the other hand, if the residence time exceeds 120 minutes, flame retardant carbon is generated by excessive heat treatment, and the whiteness of the obtained regenerated particles may decrease, or the hard substance may increase. Here, the residence time is an actual measurement time from when a metal piece that can be identified by color is introduced into the furnace body from the supply port of the workpiece 10 and discharged from the discharge port of the workpiece 10.

(Second heat treatment step)
Prior to sending the workpiece 10 to the second heat treatment step, the average particle diameter is preferably adjusted to 1 to 7 mm, preferably 1 to 5 mm, more preferably 1 to 3 mm. However, in this embodiment, a drying process is provided prior to the first heat treatment process, and the workpiece 10 is configured to be unwound in this drying process. Therefore, the average particle diameter of the workpiece 10 is usually within the above range, and the adjustment of the particle diameter can be omitted.

  In the second heat treatment step, the workpiece 10 is charged into the second heat treatment furnace 14 as the second heat treatment means. As the second heat treatment furnace 14, an external heat kiln furnace in which the furnace body is horizontally placed and rotates around the central axis is used from the viewpoint of the quality of the regenerated particles obtained and effective utilization of exhaust gas G3 (energy) described later. The second heat treatment furnace 14 may be the same shape as the first heat treatment furnace 42 as in the present embodiment. For example, the second heat treatment furnace 14 may be treated using a kiln furnace having a different axial length. The residence time of the article 10 can be different.

  In the second heat treatment furnace 14 of this embodiment, an external heat jacket 15 is provided on the outer surface of the furnace body. Exhaust gas G3 is supplied to the outer heat jacket 15 from a third exhaust gas flow path R3, which will be described later, and the object 10 deposited on the inner surface of the furnace body is indirectly heated by indirect heating by the exhaust gas G3. (External heat type) If the purpose is only the production of regenerated particles, an electric heater or the like can be used instead of supplying the exhaust gas G3. However, the configuration according to this embodiment is preferable from the viewpoint of effective use of the exhaust gas G3 (energy). It is.

  In addition, since the exhaust gas G3 is exhaust gas of the third heat treatment furnace 32, there is a possibility that a temperature fluctuation occurs momentarily (temporarily). And since the 3rd heat processing furnace 32 heat-processes at high temperature, the width | variety of the said temperature fluctuation may become large correspondingly. However, according to the form in which the exhaust gas G3 is supplied into the external heat jacket 15 and the workpiece 10 is indirectly heated, the temperature fluctuation is alleviated. In addition, when an external heating furnace is used, the oxygen concentration in the furnace body can be kept low, and thus the ignition of the workpiece 10 can be prevented as much as possible. It should be noted that a long-term temperature drop can be dealt with by providing an auxiliary heat source or the like.

  In relation to the heat treatment divided into at least four means, it is preferable to heat the outer surface of the furnace body to be 360 to 550 ° C, and more preferably to be 360 to 500 ° C. It is particularly preferable to heat to 400 to 500 ° C. When the temperature of the outer surface of the furnace body is 360 ° C. or higher, the thermal decomposition and volatilization of the styrenic organic matter in the workpiece 10 is reliably performed. In addition, since the thermal decomposition and volatilization of the styrene-based organic material is reliably performed, the heat treatment control in the third heat treatment furnace 32 is facilitated, and the generation of carbides that cause a decrease in whiteness and the generation of hard substances due to overcombustion. Can be suppressed. Furthermore, since the thermal decomposition and volatilization of the styrene-based organic material is reliably performed, the organic material such as residual carbon can be gently burned in the third heat treatment furnace 32, and the generation of residual carbon can be suppressed. . On the other hand, when the temperature of the outer surface of the furnace body is 550 ° C. or lower, generation of residual carbon in this step can be suppressed, and heat treatment of the organic matter is performed slowly, and pulverization of the workpiece 10 is suppressed. In addition, the degree of heat treatment and the grain alignment of the workpiece 10 that forms aggregates or has various properties such as hard and soft can be controlled easily and stably. On the other hand, when the temperature of the outer surface of the furnace main body is lower than 360 ° C., there is a possibility that the styrenic organic matter in the workpiece 10 cannot be sufficiently heat-treated (thermal decomposition or the like). On the other hand, when the temperature of the outer surface of the furnace body exceeds 550 ° C., there is a risk that excessive heat treatment of the workpiece 10 is performed. Further, since the combustion locally proceeds faster than the particle alignment of the workpiece 10 progresses, it becomes difficult to make the difference in the unburned ratio between the particle surface and the core portion small and uniform.

  As will be described later, in the present embodiment, the exhaust gas G5 discharged from the external heat jacket 15 is used as a heat source of the drying means 60, but as in the first heat treatment furnace 43, It can also be blown into the furnace main body (the exhaust gas flow path R8 for this purpose is indicated by a one-dot chain line in the figure). This blowing eliminates the temperature difference that occurs between the inner surface of the furnace body and the axial center, and promotes the discharge of pyrolysis gas that causes ignition from the furnace body. Further, the exhaust gas G5 is exhaust gas discharged from the external heat jacket 15 and is used as an external heat source, and therefore, energy is effectively used.

  In this case, the exhaust gas G5 is preferably supplied into the furnace body at a temperature lower than the temperature of the outer surface of the furnace body, preferably 260 to 450 ° C, more preferably 300 to 420 ° C, and particularly preferably 360 to 400 ° C. It is. If the temperature of the exhaust gas G5 supplied into the furnace body exceeds 450 ° C., the workpiece 10 may be ignited. On the other hand, when the temperature of the exhaust gas G5 is lower than 260 ° C., the difference in heat treatment temperature generated between the inner surface of the furnace body and the shaft center portion is not eliminated, and there is a possibility that it will spread.

  When the exhaust gas G5 is blown into the furnace main body of the second heat treatment furnace 14, the oxygen concentration of the exhaust gas G5 is 5.0 to 20.0%, preferably 6.0 to 18.0%, more preferably 7.0. While adjusting to ˜18.0%, the oxygen concentration of the exhaust gas (outflow gas) G2 flowing out from the furnace body of the second heat treatment furnace 14 is 0.1 to 20.0%, preferably 1.0 to 17%. It is suitable to manage to be 0.0%, more preferably 3.0 to 15.0%. Here, the oxygen concentration is a value obtained by measuring the oxygen concentration of a measurement sample sampled from each measurement region with an automatic oxygen concentration measurement apparatus (model number: ENDA-5250, manufactured by Horiba Seisakusho).

  From the viewpoint of preventing excessive heat treatment due to ignition of the object 10 to be treated, the oxygen concentration is preferably low, the oxygen concentration of the exhaust gas G5 is adjusted to 20.0% or less, and the outflow gas G2 is reduced. It is more preferable to manage the oxygen concentration to be 20.0% or less. However, if the oxygen concentration of the exhaust gas G5 is less than 5.0% or the oxygen concentration of the effluent gas G2 is less than 0.1%, the heat treatment of the styrene-based organic matter does not proceed sufficiently, and the rate of decrease in the calorific value is predetermined. It is difficult to adjust to the range, and whitening may not proceed.

  Note that the oxygen concentration in the furnace body of the second heat treatment furnace 14 may be fluctuated due to oxygen consumption during the heat treatment of the styrene-based organic matter or the like. Therefore, as in this embodiment, it is preferable to control the oxygen concentration of the exhaust gas G5 and manage the oxygen concentration of the effluent gas G2. However, by performing such adjustment and management, the oxygen concentration is usually 0.1 to 20.0%, preferably 1.0 to 17.0%, more preferably 4 in many regions within the furnace body. Adjusted to 0.0-15.0%.

  In the second heat treatment furnace 14, the residence time of the workpiece 10 is 30 to 120 minutes, preferably 40 to 100 minutes, more preferably 40 to 80 minutes. By setting the residence time to 30 minutes or longer, the organic matter derived from styrene or the like contained in the workpiece 10 is slowly heat-treated, and the generation of residual carbon is suppressed. In this regard, if the residence time is less than 30 minutes, sufficient heat treatment is not performed, and the proportion of residual carbon increases. On the other hand, if the residence time exceeds 120 minutes, flame retardant carbon is generated by excessive heat treatment, and the whiteness of the obtained regenerated particles may decrease, or the hard substance may increase.

  In the second heat treatment furnace 14, the unburned rate of the workpiece 10 is 2 to 20% by mass, preferably 5 to 17% by mass, more preferably 7 to 12% by mass. Thus, it is preferable to perform the heat treatment. Here, the unburned rate is a value obtained by measuring a weight loss ratio when burned for 2 hours in an electric furnace whose temperature is adjusted to about 600 ° C. By performing the heat treatment so that the unburned rate becomes 20% by mass or less, the heat treatment (combustion etc.) in the third heat treatment furnace 32 can be performed efficiently in a short time, and the white of the regenerated particles obtained is white The degree of whiteness can be 70% or higher, preferably 80% or higher. However, if the heat treatment is performed until the unburned ratio becomes less than 2% by mass, the energy cost in the second heat treatment furnace 14 increases, the whiteness of the regenerated particles obtained decreases, or the hardness increases. There is a risk that the quality of regenerated particles may be reduced.

(Third heat treatment step)
Prior to sending the workpiece 10 to the third heat treatment step, the average particle diameter is preferably adjusted to 5 mm or less, preferably 1 to 4 mm, more preferably 1 to 3 mm. If the average particle diameter is less than 1 mm, the workpiece 10 may be overburned in the third heat treatment furnace 32. On the other hand, if the average particle diameter exceeds 5 mm, it is difficult to heat treat (burn, etc.) the remaining carbon, the heat treatment does not proceed to the core, and the whiteness of the obtained regenerated particles may be reduced. Further, the grain alignment of the workpiece 10 is such that the ratio of the particle diameter of 1 to 5 mm is 70% by mass or more, preferably 75 to 95% by mass, more preferably 80 to 95% by mass. It is preferable to carry out such that However, in this embodiment, a drying process is provided prior to the first heat treatment process, and the workpiece 10 is configured to be unwound in this drying process. Therefore, the average particle size and the particle size of the workpiece 10 are usually within the above-mentioned range through each heat treatment step, and the adjustment of the average particle size and the particle size can be omitted.

  In the third heat treatment step, the workpiece 10 is charged into the third heat treatment furnace 32 as third heat treatment means by a charging machine (not shown). As the third heat treatment furnace 32, from the viewpoint of effective use of energy, an internal heat kiln furnace in which the furnace body is placed horizontally and rotates around the central axis is used.

  As the third heat treatment furnace 32, an external heat kiln furnace may be used. The external heat kiln furnace has an advantage that the heat treatment temperature can be easily controlled. However, the external heat kiln furnace heats the workpiece 10 indirectly, and the heat treatment efficiency does not reach that of the internal heat kiln furnace. Therefore, in the third heat treatment step in which the heat treatment temperature is relatively high, it is preferable to use an internal heat kiln furnace as in this embodiment from the viewpoint of heat treatment efficiency and productivity. In this regard, when the internal heat kiln furnace is used, the oxygen concentration in the furnace body increases, but the object to be treated 10 charged into the third heat treatment furnace 32 is made of a high amount of acrylic organic matter, cellulose, styrene organic matter, or the like. Since the calorific value component is thermally decomposed and removed, there is little possibility that the workpiece 10 will ignite.

Hot air, which is an oxygen-containing gas, is blown into the furnace body of the third heat treatment furnace 32, and is supplied from the supply port by the hot air, and is sequentially transferred to the discharge port side as the furnace body rotates. Ten heat treatments are performed. A method for generating the hot air is not particularly limited, but it is preferable to use an LPG (liquefied petroleum gas) burner L1 as a hot air source as in the present embodiment. Conventionally, heavy oil burners have been used as kiln furnace burners. However, when a heavy oil burner is used, the object to be treated 10 is contaminated by heavy oil combustion residual carbon, sulfur oxides, etc. from the heavy oil burner, resulting in a decrease in whiteness and variation in the regenerated particles obtained. The use of LPG has advantages that CO ₂ emission can be reduced, temperature control is easy, air-fuel ratio control is easy, and the workpiece 10 is not colored. In addition, when using heavy oil, A heavy oil with few sulfur content is more preferable, but LPG has the advantage more than using A heavy oil as mentioned above.

  In the third heat treatment furnace 32, the oxygen concentration of the hot air generated using the LPG burner L1 (if other hot air or dilution air is blown into the third heat treatment furnace 32 in addition to the hot air, The average oxygen concentration (hereinafter also referred to as “the oxygen concentration of the inflowing gas”) is 5.0 to 20.0%, preferably 6.0 to 18.0%, more preferably 7.0 to 18.0%. While adjusting, the oxygen concentration of the exhaust gas (outflow gas) G3 discharged from the furnace body of the third heat treatment furnace 32 is 0.1 to 20.0%, preferably 1.0 to 17.0%, more preferably. Is preferably controlled to be 3.0 to 15.0%. Here, the oxygen concentration is a value obtained by measuring the oxygen concentration of a measurement sample sampled from each measurement region with an automatic oxygen concentration measurement apparatus (model number: ENDA-5250, manufactured by Horiba Seisakusho).

  From the viewpoint of preventing excessive heat treatment of the workpiece 10, it is preferable that the oxygen concentration is low, and it is more preferable to manage the oxygen concentration of the inflow gas (oxygen-containing gas) and the outflow gas G <b> 3 to be low. However, if the oxygen concentration of the inflow gas (oxygen-containing gas) or the outflow gas G3 is too low, the heat treatment of residual carbon or residual organic matter does not proceed sufficiently, and whitening may not proceed. On the other hand, if the oxygen concentration of the inflow gas (oxygen-containing gas) or the outflow gas G3 is too high, compressed air and its additional equipment are required, the energy cost increases, and the workpiece 10 is burned or hardened. May go on. Further, in order to increase the oxygen concentration of the outflow gas G3, it is necessary to blow excess air into the furnace body, which may cause problems such as a decrease in furnace temperature and difficulty in controlling the furnace temperature. .

  Since the oxygen concentration in the furnace body is consumed and fluctuated during heat treatment of residual carbon and residual organic matter, the oxygen concentration of the inflow gas (oxygen-containing gas) is adjusted and the oxygen concentration of the outflow gas G3 is changed as in this embodiment. Management is preferred. However, by performing such adjustment and management, the oxygen concentration is usually 0.1 to 20.0%, preferably 1.0 to 17.0%, more preferably 4 in many regions within the furnace body. Adjusted to 0.0-15.0%.

  In addition, the third heat treatment furnace 32 has a temperature of hot air generated by using the LPG burner L1 (if other hot air or dilution air is blown into the third heat treatment furnace 32 in addition to the hot air, The average temperature (hereinafter also referred to as “the temperature of the inflowing gas”) is adjusted to 550 to 780 ° C., preferably 600 to 750 ° C., more preferably 650 to 720 ° C. It is preferable that the temperature of the exhaust gas (outflow gas) G3 discharged from the gas is controlled to be 550 to 780 ° C, preferably 600 to 750 ° C, more preferably 650 to 720 ° C. Here, the temperature of the outflow gas G3 is a value obtained by actually measuring the temperature with a thermocouple installed in the flue (the third exhaust gas flow path R3) of the outflow gas G3. Further, the temperature of the inflowing gas is a value obtained by actually measuring the temperature with a thermocouple in the flue of the inflowing gas. In addition, when there are a plurality of inflowing gases, the value is calculated from the value obtained by actually measuring the temperature with a thermocouple and the flow rate in each flue.

  If the temperature of the inflow gas is 550 ° C. or more and the temperature of the outflow gas G3 is also 550 ° C. or more, the residual carbon in the object 10 or styrene-acrylic or styrene that could not be heat-treated in the second heat treatment furnace 14 Heat treatment of residual organic matter such as is reliably performed. On the other hand, when the temperature of the inflow gas is 780 ° C. or less and the temperature of the outflow gas G3 is 780 ° C. or less, the generation of residual carbon can be suppressed, and the heat treatment of the organic matter is performed slowly. 10 can be easily and stably controlled in terms of the degree of heat treatment and the grain alignment of the object to be processed 10 having various properties such as agglomerates or being hard and soft. . In this respect, if the temperature of the inflowing gas exceeds 780 ° C. or the temperature of the outflowing gas G3 exceeds 780 ° C., the combustion proceeds locally faster than the particle alignment of the workpiece 10 progresses. It is difficult to make the difference in unburnt ratio between the core and the core small and uniform. Moreover, when the obtained regenerated particles are slurried, they may be hardened.

  Since the temperature in the furnace body has a temperature gradient and is not uniform, it is preferable to adjust the temperature of the inflowing gas and manage the temperature of the outflowing gas G3 as in this embodiment. However, by performing such adjustment and management, the temperature in many regions in the furnace body is the same as that in the above adjustment and management, that is, usually 550 to 780 ° C., preferably 600 to 750 ° C., more preferably 650. Adjusted to ˜720 ° C. The temperature in the furnace body is a value measured with a thermocouple installed in the furnace body.

  In the third heat treatment furnace 32, the residence time of the workpiece 10 is 60 to 240 minutes, preferably 90 to 150 minutes, more preferably 120 to 150 minutes. By setting the residence time to 60 minutes or longer, the residual organic matter and residual carbon contained in the workpiece 10 are reliably heat-treated, and the regenerated particles can be stably produced. On the other hand, when the residence time exceeds 240 minutes, the decomposition of calcium carbonate is promoted, and the whiteness of the obtained regenerated particles may be reduced, or the hard substance may be increased. In this regard, the first heat treatment furnace 42 is heat-treated so that the calorific value of the object to be treated 10 is reduced by 20 to 90%, and the acrylic organic matter and cellulose are thermally decomposed. When heat treatment is performed so that the styrene-based organic matter of the product 10 is thermally decomposed, the residence time of the object 10 to be processed in the third heat treatment furnace 32 can be shortened, and overburning, reduction in whiteness, Risk such as increase can be reduced.

  The object to be processed 10 discharged from the third heat treatment furnace 32 is preferably an agglomerate, and is appropriately pulverized and then cooled in a cooler 34 and then by a particle size selector 36 such as a vibration sieve. After selection, the particles are temporarily stored in the silo 38 as regenerated particles, and are appropriately sent to applications such as fillers and pigments.

(Regenerated particles)
The regenerated particles obtained by the method for producing regenerated particles according to the present embodiment have a ratio of calcium, silica, and aluminum of 30 to 82: 9 to 35: 9 to 35 in terms of oxides in elemental analysis of fine particles using an X-ray microanalyzer. The mass ratio is When the ratio of calcium, silica and aluminum is 30 to 82: 9 to 35: 9 to 35 in terms of oxide, the specific gravity is light and excessive aqueous solution absorption is suppressed, so that dehydration is good. It is.

  By the way, the amount of used calcium carbonate as a filler / pigment for used paper that can be said to be the raw material of the object to be treated 10 increases with the use of coated paper with good printing appearance due to the progress of neutral papermaking and visualization in recent years. The increase leads to an increase in the content of calcium carbonate in the papermaking sludge, and as a result, an increase in the amount of gelenite and anorthite generated. The need to reduce is growing. Therefore, the above-mentioned method for producing regenerated particles capable of reducing the content of the hard substance is extremely useful, and the regenerated particles of this embodiment produced by this production method have a total content of gehlenite and anorthite of 1. It is 5 mass% or less, Preferably it is 1.0 mass% or less, More preferably, it is 0.5 mass% or less.

Note that gehlenite (Ca ₂ Al ₂ SiO ₇ ) and anorsite (CaAl ₂ Si ₂ O ₈ ), which are hard materials, are extremely hard compared to fillers and pigments used for papermaking, Wear and damage of papermaking tools and dirt in the papermaking system occur, and when used as a coating pigment, it causes wear and damage of coating equipment such as doctors and streaks. Moreover, the total content of gehlenite and anorthite is a value measured by the following method.

(Measuring method)
It is measured by X-ray diffraction method (manufactured by Rigaku Denki, RAD2X). Measurement conditions are: Cu-Kα-curved monochromator: 40 KV-40 mA, divergence slit: 1 mm, SS: 1 mm, RS: 0.3 mm, scanning speed: 0.8 degrees / minute, scanning range: 2 theta = 7 to 85 Degree, sampling: 0.02 degree.

(Effective energy)
In the method for producing regenerated particles of this embodiment, heat generated more than heat treatment occurs from the object to be processed 10, and conversely, this heat generation is a factor of overcombustion. It is a thing. Details will be described below.

  In this embodiment, only the aforementioned LPG burner L1 is provided as the main heat generating device (hot air source). The hot air generated using the LPG burner L1 is blown into (supplied to) the furnace body of the third heat treatment furnace 32 and used as an internal heat source.

  From which part of the third heat treatment furnace 32 the hot air generated using the LPG burner L1 is blown is not particularly limited. The third heat treatment furnace 32 is “a horizontal rotation in which a supply port for the workpiece 10 is provided on one end side 32A of the furnace body and a discharge port for the workpiece 10 is provided on the other end side 32B of the furnace body. In this embodiment, which is a “kiln furnace”, for example, although not shown, the hot air is blown from one end portion side (hereinafter also referred to as “supply port side”) 32A, and the exhaust gas G3 in the furnace body is discharged to the other end. It can also be set as the form discharged | emitted from the part side (henceforth "the discharge port side") 32B (parallel flow system). In addition, the to-be-processed object 10 heated with the said hot air is supplied from the supply port side 32A, and is sequentially transferred to the discharge port side 32B with rotation of a furnace main body. In this way, when the hot air supply method is a cocurrent flow method, the workpiece 10 in a relatively low temperature state is immediately heated to a temperature suitable for heat treatment of residual carbon or the like. In addition, since a temperature gradient that lowers the temperature from the supply port side 32A toward the discharge port side 32B is generated, excessive heat treatment of the workpiece 10 is prevented.

  However, in the present embodiment, the main hot air is blown from the discharge port side 32B, and the exhaust gas G3 in the furnace body is discharged from the supply port side 32A (counterflow method). By using the counter-current system, it is possible to reliably prevent the quality of the regenerated particles obtained by mixing the dust in the exhaust gas G3 into the workpiece 10 from being deteriorated. That is, in the third heat treatment furnace 32, the remaining carbon in the supplied workpiece 10 is immediately subjected to a heat treatment such as combustion. Thus, the generated dust is quickly discharged from the supply port side 32 </ b> A together with the exhaust gas G <b> 3 to the outside of the furnace body and is prevented from being mixed into the workpiece 10.

  The exhaust gas G3 discharged from the inside of the furnace body of the third heat treatment furnace 32 is supplied into the external heat jacket 15 provided in the second heat treatment furnace 14 through the third exhaust gas flow path R3. Used as an external heat source. The exhaust gas G3 passed through the third exhaust gas flow path R3 is heated as necessary by a burner B1 provided in the middle of the flow path R3, so that the heat treatment temperature in the second heat treatment furnace 14 is increased. Adjusted.

  Similarly to the third heat treatment furnace 32 except for the presence or absence of the external heat jacket 15, the second heat treatment furnace 14 of this embodiment is also provided with a supply port for the workpiece 10 on one end side 14 </ b> A of the furnace body, The horizontal rotary kiln furnace is provided with a discharge port for the workpiece 10 on the other end side 14B of the furnace body.

  For example, the exhaust gas G2 in the furnace main body of the second heat treatment furnace 14 may be discharged from the other end side (hereinafter also referred to as “exhaust port side”) 14B, although not shown. However, in this embodiment, the exhaust gas G2 is discharged from one end portion side (hereinafter also referred to as “supply port side”) 14A. As the exhaust gas G2 is discharged from the supply port side 14A, the quality of the regenerated particles obtained by mixing the dust in the exhaust gas G2 into the object to be treated 10 is lowered, as in the case of the third heat treatment means 32 described above. Is reliably prevented. However, in this embodiment, the heat treatment of the workpiece 10 is performed by dividing into four means, and the heat treatment in the second heat treatment furnace 14 is performed at the lowest possible temperature. Therefore, the heat treatment in the second heat treatment furnace 14 is not the combustion of organic matter but mainly the thermal decomposition of styrenic organic matter, and there is almost no possibility of generating dust. In addition, when the heat treatment temperature is low, the pyrolysis gas (combustible gas) generated by the thermal decomposition of the styrene-based organic substance is less likely to ignite (combust) in the furnace body, and is directly used as exhaust gas G2 in the furnace body. Discharged from. Therefore, there is no possibility of overcombustion of the workpiece 10.

  As described above, since the main component of the exhaust gas G2 is a pyrolytic gas of styrene-based organic matter, the exhaust gas G2 has an extremely large amount of heat. Therefore, in the present embodiment, the exhaust gas G2 is supplied into the external heat jacket 43 provided in the first heat treatment furnace 42 through the second exhaust gas flow path R2, and is effectively used as an external heat source of the first heat treatment furnace 42 and the like. It is configured as follows. More specifically, first, the exhaust gas G2 passing through the second exhaust gas flow channel R2 is ignited by a burner B2 or the like provided in the middle of the flow channel R2 to be a high-temperature combustion gas. The second exhaust gas flow channel R2 is branched from the fourth exhaust gas flow channel R4, and a part of the exhaust gas G2 is supplied into the external heat jacket 43 provided in the first heat treatment furnace 42. It is used as an external heat source, and the remaining part of the exhaust gas G2 is diverted to the fourth exhaust gas channel R4.

  Although not shown, an air mixing means for mixing air or the like into part of the exhaust gas G2 can be provided on the first heat treatment furnace 42 side of the second exhaust gas channel R2. The heat treatment temperature in the first heat treatment furnace 42 can be adjusted by adjusting the air mixing amount from the air mixing means. The heat treatment temperature can also be adjusted by adjusting the ratio of the exhaust gas G2 to be diverted to the fourth exhaust gas channel R4.

  In this respect, the exhaust gas G2 is burned by ignition by the burner B2 and the like, and has a low oxygen concentration. After passing through the outer heat jacket 43, the exhaust gas G2 is blown into the furnace body of the first heat treatment furnace 42. . Therefore, it is preferable to mix the air with care so that the oxygen concentration of the exhaust gas G2 does not become higher than necessary.

  The first heat treatment furnace 42 of this embodiment is also provided with a supply port for the workpiece 10 on one end side 42A of the furnace main body, similarly to the third heat treatment furnace 32 except for the presence or absence of the external heat jacket 43, The horizontal rotary kiln furnace is provided with a discharge port for the workpiece 10 on the other end side 42B of the furnace body.

  The exhaust gas G1 in the furnace main body of the first heat treatment furnace 42 may be discharged from the other end side (hereinafter also referred to as “discharge port side”) 42B, for example, although not shown. However, in this embodiment, the exhaust gas G1 is discharged from one end side (hereinafter also referred to as “supply port side”) 42A. As the exhaust gas G1 is discharged from the supply port side 42A, the quality of the regenerated particles obtained by mixing the dust in the exhaust gas G1 into the object to be processed 10 is reduced as in the case of the third heat treatment means 32 described above. Is reliably prevented. However, in this embodiment, the heat treatment of the workpiece 10 is performed by dividing into four means, and the heat treatment in the first heat treatment furnace 42 is performed at the lowest possible temperature. Therefore, the heat treatment in the first heat treatment furnace 42 is not the combustion of organic matter but mainly the thermal decomposition of acrylic organic matter and cellulose, and there is almost no possibility of generating soot. Moreover, when the heat treatment temperature is low, the pyrolysis gas (combustible gas) generated by the pyrolysis of the acrylic organic matter and cellulose is less likely to ignite (combust) in the furnace body, and There is little risk of overcombustion.

  As described above, since the main component of the exhaust gas G1 is a pyrolysis gas of acrylic organic matter and cellulose, the exhaust gas G1 has an extremely large amount of heat. Therefore, in the present embodiment, the exhaust gas G1 is sent to the drying device 60 through the first exhaust gas flow path R1, and is effectively used as a heat source for the drying device 60 and the like. More specifically, first, the exhaust gas G1 flowing in the first exhaust gas passage R1 is ignited by a burner B3 or the like provided in the middle of the passage R1 to be a high-temperature combustion gas. The first exhaust gas channel R1 is connected to the fifth exhaust gas channel R5 in the middle thereof. The other end of the fifth exhaust gas flow path R5 is connected to the external heat jacket 15 of the second heat treatment furnace 14, and the exhaust gas G5 after being used as an external heat source in the second heat treatment furnace 14 flows therethrough. It is. Further, the fifth exhaust gas flow path R5 is connected to the fourth exhaust gas flow path R4 in the middle thereof, and the exhaust gas G5 flowing in the fifth exhaust gas flow path R5 is connected to the fourth exhaust gas flow path R4. The remaining portion G4 of the exhaust gas G2 flowing through is mixed. Therefore, the exhaust gas G1 flowing in the first exhaust gas channel R1 is mixed with the exhaust gas G5 flowing in the exhaust gas channel R5 and the remaining part G4 of the exhaust gas G2 mixed in the exhaust gas G5. The mixed gas G composed of the exhaust gases G1, G4, G5 and the like thus formed is sent to the drying device 60 through the exhaust gas flow path R1, and is effectively used as a heat source of the drying device 60. Further, an air mixing means for mixing the diluted air A2 into the mixed gas is provided on the drying device 60 side of the first exhaust gas channel R1. Therefore, by adjusting the mixing amount of the dilution air A2, the heat treatment (drying) temperature in the drying device 60, the flow velocity / flow rate of the hot air current, and the like can be adjusted.

  On the other hand, the exhaust gas G7 discharged from the external heat jacket 43 of the first heat treatment furnace 42 is blown into the furnace main body of the first heat treatment furnace 42 through the exhaust gas flow path R7, and the thermal energy is effectively used. In the illustrated example, the exhaust gas G5 discharged from the external heat jacket 15 of the second heat treatment furnace 14 is used as a heat source of the drying device 60, but part or all of the exhaust gas G5 passes through the exhaust gas flow path R8. It is also possible to blow into the furnace body of the second heat treatment furnace 14. In either method, the thermal energy is effectively used. However, when the heat energy is blown into the furnace main body of the second heat treatment furnace 14, a difference in heat treatment temperature generated between the inner surface of the furnace main body and the shaft center portion is generated. Moreover, the discharge of pyrolysis gas, which causes ignition, from the furnace body is promoted.

  In this embodiment, the shape, material, and the like of each of the flow paths R1 to R7 are not particularly limited, and a known exhaust gas or the like can be used.

  Table 1 shows the amount of heat in each facility (drying apparatus, heat treatment furnace, exhaust gas flow path, etc.) in the case of producing regenerated particles by the above method. This amount of heat exemplifies the case where the processing object 10 at 20 ° C. is supplied to the drying apparatus 60 at a supply rate of 8.93 t / h, and LPG for generating hot air is used at a rate of 65 kg / h. is there. Note that this example is not intended to limit the method of this embodiment only to such a heat amount.

  According to the method of this example, the workpiece 10 is heated to 100 ° C. in the drying device 60, sent to the first heat treatment furnace 42 at a rate of 5.35 t / h, and 370 in the first heat treatment furnace 42. The second heat treatment furnace 14 is heated to 410 ° C. at a rate of 4.23 t / h, and is heated to 410 ° C. in the second heat treatment furnace 14 at a rate of 3.75 t / h. It is sent to the furnace 32, heated to 680 ° C. in the third heat treatment furnace 32, and sent to the subsequent process at a rate of 3.75 t / h. The temperature of the hot air supplied to the third heat treatment furnace 32 is 700 ° C., the temperature of the exhaust gas G 2 discharged from the second heat treatment furnace 14 is 410 ° C., and the temperature of the exhaust gas G 1 discharged from the first heat treatment furnace 42. The temperature is estimated to be 340 ° C., and the temperature of the mixed gas G supplied to the drying device 60 is 450 ° C. In addition, the code | symbol in Table 1 respond | corresponds with the code | symbol in FIG.

Next, examples and comparative examples for clarifying the effects of the present invention will be shown.
An object to be treated (sample) made of paper sludge in general or deinked floss was dehydrated, heat treated and wet pulverized to produce regenerated particles. The processing conditions in each step are shown in Tables 2 to 5. The “airflow drying” in the device format means a case where an apparatus capable of drying a processed object after being dehydrated with a hot airflow is used. Specifically, an airflow drying apparatus (model number: Kudakera) is used. , Made by Shin Nihonkai Heavy Industries Co., Ltd.). The furnace type “kiln” means a case where a horizontal rotary kiln furnace (rotary kiln furnace) in which the main body is placed horizontally and rotates around the central axis is used. Furthermore, a ceramic ball mill was used in the wet grinding process. Unless otherwise specified, the following measurement method, evaluation method, and the like are the same throughout this specification.

  The quality of the regenerated particles obtained as described above was examined, and the results are shown in Table 6.

The measuring means and the evaluation method in the examples and comparative examples are as follows.
(Moisture percentage)
The sample was allowed to stand in a constant-temperature dryer, and when it was kept at about 105 ° C. for 6 hours or longer and no mass fluctuation was observed, the weight after drying was calculated, and the moisture content was calculated by the following formula.
Moisture content (%) = (mass before drying−mass after drying) ÷ mass before drying × 100

(Average particle size)
Sieving with sieves with different eye holes, measuring the mass of each sieving material, the size of the eye holes of the sieves at the stage where the total value of these measured values corresponds to 50% by mass of the whole It is a value measured using a metal plate sieve based on JIS Z 8801-2: 2000.

(Ratio of particle diameter 50mm or more)
When the mass of the entire sample is 100, it is the mass ratio of the sample that did not pass through the sieve having a 50-mm hole. In this measurement, a metal plate sieve was used based on JIS Z 8801-2: 2000.

(Oxygen concentration)
It is the measured value of the oxygen concentration of the sample sampled from each measurement area with an automatic oxygen concentration measuring device (model number: ENDA-5250, manufactured by Horiba Seisakusho).

(temperature)
It is the value which measured the temperature of each area | region (exhaust gas flow path (smoke), the inside of a furnace main body, the outer surface of a furnace main body, etc.) with the thermocouple.

(Residence time)
This is a value obtained by actually measuring the time until a metal piece that can be identified by color is put into the furnace body and the metal piece is discharged from the discharge port of the object to be processed.

(Heat generation reduction rate)
This is a value calculated from the reduction rate by measuring the calorific value of the sample before heat treatment and the sample after heat treatment using a calorimeter (Nanken digital calorimeter, manufactured by Yoshida Seisakusho).

(Unburnt rate)
This is a value calculated from the change in mass before and after combustion, after heating the electric muffle furnace to 600 ° C. in advance, putting the sample in a crucible and burning it completely in about 2 hours.

(Hard substance)
It is the value which measured the total mass of the gehlenite and anorthite contained in each obtained reproduction | regeneration particle | grain by the X-ray diffraction method (Rigaku Corporation: RAD2X). Measurement conditions are: Cu-Kα-curved monochromator: 40 KV-40 mA, divergence slit: 1 mm, SS: 1 mm, RS: 0.3 mm, scanning speed: 0.8 degrees / minute, scanning range: 2 theta = 7 to 85 Degree, sampling: 0.02 degree.

((Wire) wear degree)
Each of the obtained regenerated particles is a value measured at a slurry concentration of 2% by mass using a plastic wire wear meter (manufactured by Nippon Filcon, 3 hours).

(Dispersibility)
This is a value obtained by measuring the viscosity of the regenerated particle slurry (60% concentration) after pulverization using a B-type viscometer at a rotor rotational speed of 6 rpm. In addition, it was determined that the lower the viscosity (mPa · s), the better the dispersibility.

(Appearance)
The color of the regenerated particles was visually judged and classified into high white, white, gray, dark gray, and black.

(Stability)
Measure the percentage of variation in the whiteness and average particle size of each regenerated particle, rank it in order of decreasing variation, rank the top 5 to ◎, rank 6-19 to △, rank 20 to 23, △ The following was set as x.

  The present invention can be applied as a method for producing regenerated particles by dehydrating and heat-treating an object to be processed using papermaking sludge as a main raw material.

  DESCRIPTION OF SYMBOLS 10 ... Raw material, 12 ... Storage tank, 14, 32, 42 ... Heat treatment furnace, 15, 43 ... External heat jacket, 22 ... Exhaust gas treatment equipment, 30 ... Chimney, 34 ... Cooling machine, 36 ... Particle size sorter, 38 ... Silo B1-B3 ... burner, G-G7 ... gas, R1-R7 ... flow path, 60 ... drying apparatus.

Claims (4)

A process for producing regenerated particles by dehydrating and heat-treating an object to be processed using papermaking sludge as a main raw material,
The heat treatment includes a drying means for drying the dehydrated article, a first heat treatment means for heat treating the article dried by the drying means, and a treatment heat treated by the first heat treatment means. A second heat treatment means for heat-treating the product at a temperature exceeding the first heat treatment temperature; and a third heat treatment for treating an object heat-treated at the second heat treatment means at a temperature exceeding the second heat treatment temperature. Heat treatment means, and divided into at least four means,
At least one of the first heat treatment means and the second heat treatment means is an external heat furnace in which an external heat jacket is provided on the outer surface of the furnace body, and hot air is supplied into the external heat jacket,
Injecting exhaust gas discharged from the outer heat jacket into the furnace body,
A method for producing regenerated particles.   The method for producing regenerated particles according to claim 1, wherein exhaust gas discharged from the furnace body or from the furnace body of another heat treatment means is used as hot air supplied into the outer heat jacket. Both the first heat treatment means and the second heat treatment means are provided as an external heat furnace in which an external heat jacket is provided on the outer surface of the furnace body, and hot air is supplied into the external heat jacket. While the heat treatment means is an internal heating furnace in which hot air is blown into the furnace body,
Supplying the exhaust gas discharged from the furnace body of the third heat treatment means into the outer heat jacket of the second heat treatment means,
Supplying a part of the exhaust gas discharged from the furnace body of the second heat treatment means into the outer heat jacket of the first heat treatment means;
Exhaust gas discharged from the furnace body of the first heat treatment means, the remainder of the exhaust gas discharged from the furnace body of the second heat treatment means, and an external heat jacket of the second heat treatment means Using exhaust gas as a heat source for the drying means,
Injecting exhaust gas discharged from the external heat jacket of the first heat treatment means into the furnace body of the first heat treatment means,
The method for producing regenerated particles according to claim 1 or 2. Injecting exhaust gas discharged from the external heat jacket of the second heat treatment means into the furnace body of the second heat treatment means,
The temperature of the outer surface of the furnace body of the first heat treatment means is 250 to 400 ° C., the temperature of the outer surface of the furnace body of the second heat treatment means is 360 to 550 ° C., and the temperature inside the furnace body of the third heat treatment means Becomes 550-780 ° C., the temperature of the exhaust gas blown into the furnace body of the first heat treatment means is 150-350 ° C., and the temperature of the exhaust gas blown into the furnace body of the second heat treatment means becomes 260-450 ° C. To control,
The method for producing regenerated particles according to claim 3.

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