JP3352019B2 - Paper sludge carbonized fired material and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous granular carbonized fired product having open cells produced by reducing and firing paper sludge, and a method for producing the same.

[0002]

The most problematic waste in the recycled paper industry is paper sludge. Paper sludge is industrial wastewater treatment sludge discharged from a recycled paper mill using waste paper as a raw material. The paper sludge contains approximately the same amount of paper fiber (cellulose) as a clay inorganic component and an organic component, which are present as fillers in raw waste paper.
At present, waste paper sludge is incinerated or landfilled. However, it is urgently necessary to take new disposal measures to secure the disposal site and reduce the environmental burden around the disposal site.

Up to now, paper sludge has been partially used as a fertilizer raw material, an antioxidant for ironmaking, a humectant, an asphalt sheet filler, and a soil improvement material. Attempts have been made to carbonize paper sludge. I didn't.

[0004]

Research on the recycling of paper sludge has been conducted by various research institutes. However, it has high discharge, high water content, paper fiber (organic matter) and filler. Effective utilization of paper sludge is still one of the major issues in the recycled paper industry because of the difficulty of separating (inorganic substances), the high transportation cost and the difficulty in differentiating existing products. .

In the present invention, it has been found that a porous granular carbide excellent in water absorption obtained by carbonizing and firing paper sludge is effective as a soil improvement material, a snow melting material, a humidity control material, an adsorbent and a siliceous material. And recycled paper sludge.

[0006]

Means for Solving the Problems The fired porous granular carbonized product of the present invention has a flammable content of 10 to 20% by absolute dry weight (JIS).
K1474), SiO ₂ ;
35%, Al ₂ O ₃ ; 15 to 20%, Fe ₂ O ₃ ;
%, CaO; 10 to 20%, MgO; 5 to 15% and others; 1 to 3%, and the water absorption according to JIS C2141 is 70 to 150%, preferably 100 to 150%.
The specific surface area by the BET adsorption method is 60 to 120.
m ² / g, preferably 80 to 120 ² / g, porosity is 60-80%, pH by JIS K1474 is 8.0 to 11.0, preferably 8.5 to 10.
0 is a black, paper-sludge carbonized fired product having a diameter (height) of 2 to 8 mm in a spherical, elliptical, rugby ball or cylindrical shape having open cells.

Although the present invention has been described from the composition of SiO _{2 and} the like as described above, the carbonized and baked product of the present invention can be described as follows from the viewpoint of physical structural characteristics such as voids. can do.

That is, the present invention has a volume porosity (by mercury porosimeter method) of 75% or more, a void volume (by mercury porosimeter method) of 1500 mm ³ / g or more, and an average pore radius of 20 to 60 μm. A black porous granular carbonized product in which voids having a radius of 1 μm or more in the total void volume are 70% or more. The gap of 1 μm or more enhances the water absorption performance. This porous granular carbonized fired product can have a major axis of 2 to 8 mm, and is usually spherical,
It has an elliptical shape, a rugby ball shape or a cylindrical shape, but other shapes are also possible. The carbonized fired product of the present invention has a saturated hydraulic conductivity by a variable water level method of 3.0 to 8.0 × 10 ⁻² cm / s, preferably 4 to 5 mm for a diameter of 3 to 5 mm.
8 to 5.9 × 10 ⁻² cm / s. This value is the same as that of ordinary zeolite (saturated hydraulic conductivity is 1.8 ×
10 ^-2 cm / s, a natural species from Hokkaido, with a pore volume of about 200 mm ³ / g and an average pore radius of about 0.3 to about 0.4 nm. Good permeability (drainage). This indicates that when applied to a field as a soil improvement material, water unnecessary for plants is quickly removed. When unnecessary water is not removed quickly,
In poorly drained soil, growth is significantly inhibited, depending on the plant species. With respect to the porosity, water retention and water retention over time, it has been confirmed that the carbonized fired product of the present invention is almost equivalent to zeolite.

The method for producing a porous granular carbonized fired product of the present invention comprises granulating paper sludge having a water content of 50 to 65%, spheroidizing, drying, and then carbonizing and firing in a reduced carbonizing and firing furnace. In this production method, if the granulation treatment is performed by one apparatus, it is impossible to perform granulation having a uniform particle size distribution. Spheroidizing process (sizing process)
And go separately. In the granulating step, a disk pelletizer, a fine disk pelleter, a dish-type granulator, a marmellaizer and the like can be used, but a disk pelleter is preferable. After extrusion granulation with a disc pelletizer and the like to make the particle size uniform, spheroidization is performed using a drum type granulator, a dish type (bread type) granulator and a marmellaizer.
A drum type granulator capable of continuous processing is preferred.

[0010] In the spheroidizing step, water is sprayed as a binder agent into a drum type granulator or the like. As a result, the viscosity of the surface of the columnar particles granulated by the disk pelleter or the like is increased, the fine particles are absorbed, and spheroidization is promoted.

In the carbonization firing step, a dry distillation carbonization furnace can be used, and a continuous type is preferred. After the spheroidization, when dry paper sludge is introduced into the carbonization furnace, carbonization gas is generated, but all of the gas is completely burned in the furnace, so there is no problem of exhaust gas.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Paper sludge having a water content of 50 to 65% obtained by precipitating SS in service water circulated in a recycled paper mill with a clarifier and dewatering the extracted SS with a screw press is put into a hopper. Then, a fixed amount is continuously fed into the disk pelletizer by a screw feeder. The introduced paper sludge is 3 to 5 mm placed at the bottom of the granulation chamber in the disk pelletizer.
Is pressed by a roller against a disc having a myriad of arbitrary holes, and is formed into a cylindrical shape having a diameter of 3 to 5 mm and a length of 20 to 30 mm having an arbitrary bottom diameter controlled by the diameter of the disc hole after passing through the disc hole. Is done. The paper sludge formed and adjusted to a certain size is continuously conveyed to a drum type granulator by a belt conveyor, and charged into the drum. The drum rotates at 10 to 30 rpm, and the cylindrically-adjusted paper sludge charged therein is appropriately crushed by collision with the inner wall surface of the drum, friction and collision between particles. At the time of crushing, the crushed paper sludge adjusted to an appropriate L / D, which approaches the diameter of the bottom of the cylinder, is evenly distributed using 3 to 4 spray nozzles installed at an interval of about 15 cm in the front of the inside of the drum with water as a binder. Spray. The surface of the paper sludge adjusted into a columnar shape is wetted and softened by the spray of water, and the viscosity increases. As a result, fine paper sludge particles having a diameter of 2 mm or less generated during the crushing of the columnar paper sludge are adsorbed by the large particles. Furthermore, since the surface is softened, the formability is improved, and as the inside of the drum rolls on its own foot, it becomes spherical while absorbing fine particles. To prevent sticking of paper sludge inside the drum,
A rubber sheet fixed at two or three points is stuck on the inner wall of the drum, and hangs down by gravity at the upper part of the rotating drum. As a result, the attached particles are shaken off. The residence time of the drum type granulator is 3 to 8 minutes, and the amount of water to be sprayed is 5 to 20% based on the weight of the paper sludge to be charged. The amount of water added depends on the temperature of the water to be added and the temperature of the paper sludge.

After passing through a drum-type granulator, the spherical paper sludge adjusted to a uniform particle size is then sent to a drying step. In the drying step, the water is dried to about 3 to 40% by a rotary kiln by heat generated in a subsequent baking furnace. Drying shrinks the paper sludge and increases the particle density.

The dried granulated paper sludge is carbonized and calcined at a carbonization temperature of 550 to 750 ° C. in a continuous carbonization furnace. The carbonization gas generated when carbonizing and firing the paper sludge burns in the furnace. The amount of heat generated during the combustion of the carbonization gas is used to maintain the furnace temperature or as a heat source in the drying process in the preceding stage. The residence time of the paper sludge in the continuous carbonization furnace is 5 to 20 minutes.

When the combustion is completely completed, water or an aqueous solution containing a fertilizer component is sprayed to lower the temperature of the carbonized fired product. Thus, a sphere with open cells,
Oval, rugby ball or columnar diameter 2-8mm
To obtain a black carbonized fired product.

[0016]

[Example] Paper with a water content of 57% obtained by precipitating SS in water circulated in a recycled paper mill in Abuta-gun, Hokkaido of Doei Paper Industry Co., Ltd. with a clarifier and dewatering it with a screw press. 5 m ³ of sludge is put into a hopper and 450 kg / h by a screw feeder.
, And continuously introduced into a disk pelletizer (Fuji Paudal). The introduced paper sludge is pressed by a roller against a 5 mm thick disk having a myriad of 3 mm arbitrary holes installed at the bottom of the granulation chamber in the disk pelleter, passes through the disk holes, and passes through the disk holes. 20-30m with arbitrary bottom diameter controlled by diameter
m (FIG. 1). The paper sludge was continuously conveyed to a drum type granulator (manufactured by Hokuko Kakoki Co., Ltd.) by a belt conveyor, and was charged into the drum. The drum was rotated at 20 rpm, and the charged columnar paper sludge was appropriately pulverized. At the time of pulverization, water was uniformly sprayed as a binder agent to a front portion in the drum by a spray nozzle, and the amount of water to be sprayed was 13% based on the weight of paper sludge. The paper sludge rolled on its own inside the drum and became spherical. The residence time of the drum type granulator was set to 5 minutes, and the spherical paper sludge adjusted to a uniform particle size was sent to a drying step to obtain a spherical paper sludge dried to a water content of about 10% (FIG. 2). Utilizing the heat generated in the subsequent baking furnace, it was dried to a water content of 7% in a rotary kiln. The dried paper sludge granules were carbonized and fired at a furnace temperature of 800 ° C. (combustion temperature of 600 ° C.) in a continuous external heating rotary kiln (manufactured by Takasago Industry Co., Ltd.) and allowed to stay for 15 minutes. When the firing was completely completed, the temperature of the carbonized fired product was lowered to obtain a black carbonized fired product (FIG. 3). The results of component analysis of the carbonized fired product were as follows. Combustible content: 16.1%, SiO ₂ : 33.
1%, Al ₂ O ₃ : 17.8%, Fe ₂ O ₃ : 10.32.
%, CaO: 13.93%, MgO: 7.55% and others: 1.20%, water absorption: 100 g of absolutely dry granulated material
The specific surface area by the BET adsorption method: 77.28 m ² / g, and the p according to JIS K1474.
H: 8.1, void volume by mercury porosimetry method: 1
The average void radius was 704 mm ³ / g, the average void radius was 53 μm, and the volume void ratio was 85%. In addition, the radius 0.87μ by the same method
The voids of m or more were 76% of the total void volume. further,
The saturated hydraulic conductivity by the variable water level method is 3 mm in diameter.
It was 8 × 10 ^-2 cms ^-1 . For a diameter of 5 mm, 5.9
× 10 ^-2 cms ^-1 .

[0017]

The porous granular carbonized fired product of the present invention has a radius of 1
Since there is a large void of μm or more, the water absorption performance is high, and the water permeability as a soil improvement material is high. Therefore, application to soil with poor drainage is effective. On the other hand, since it has the water retention property of a normal zeolite, it also has a soil improvement effect on dry soil. This carbonized and fired product has a black color and is effective as a snow melting material. It is also useful as a humidifier and adsorbent.

In the production of the porous granular carbonized fired product of the present invention, it is possible to use only paper sludge without using any additives such as a binder in the paper sludge granulation step. Further, in the firing in a reducing environment, the reduction energy can be fired to some extent by self-combustion by utilizing the thermal energy of the paper sludge itself. As a result, it is possible to reduce the energy cost in production, which is a major issue of recycling of waste, and to eliminate the cost of raw materials for additives, thereby significantly reducing the production cost of carbonized fired products.

It is possible to recycle paper sludge, which is industrial waste, which has been the biggest problem in the recycled paper industry. A recycled paper mill manufactures paper products from waste paper raw materials as waste, and the production process. Since 100% of the paper sludge generated from the wastewater can be recycled into a porous granular carbonized fired product, the factory can be closed.

Further, since it contains 20% or more of silicic acid, it can be used as siliceous fertilizer.

[Brief description of the drawings]

FIG. 1 shows a paper sludge obtained by granulating a paper sludge with a disk pelletizer by a method shown in Examples of the present invention.
3 is a photograph showing columnar particles of mm.

FIG. 2 is a photograph showing spherical particles obtained by spheroidizing the columnar particles of FIG. 1 with a drum type granulator and then drying.

FIG. 3 is a photograph showing carbonized fired product particles of the present invention obtained by carbonizing and firing the dried paper sludge granulated product of FIG. 2;

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C04B 35/52 C04B 38/00 304B 38/00 304 35/52 B (56) References JP-A-2-107398 (JP, A JP-A-10-330748 (JP, A) JP-A-9-87634 (JP, A) JP-A-6-285498 (JP, A) JP-A-3-26335 (JP, A) JP-A-63-1988 46288 (JP, A) JP-A-51-114220 (JP, A) JP-A-5-106218 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C10B 53/00-53 / 08 C09K 17/02-17/12

Claims (4)

(57) [Claims] 1. An absolutely dry weight, flammable content: 10 to 20%, S
_{iO 2: 20~35%, Al 2} O 3: 15~20%, Fe 2
O ₃ : 5 to 15%, CaO: 10 to 20% and MgO:
5-15%, the water absorption according to JIS C2141 is 70-150%, the specific surface area according to the BET adsorption method is 60-120 m ² / g, and JIS K147.
A porous granular paper sludge carbonized fired product having open cells having a pH of 8.0 to 11.0 according to 4. 2. The method according to claim 1, wherein the paper sludge having a water content of 50 to 65% is granulated, spheroidized, dried, and then carbonized and calcined at a carbonization temperature of 550 to 750 ° C. in a reduced carbonizing and calcining furnace. Porous granular paper with open cells
-A method for producing a sludge carbonized fired product. 3. A volume porosity of 75% or more and a void volume of 1
500 mm ³ / g or more, and the average void radius is 20 to 6
0 μm, and black porous granular paper slats having a void having a radius of 1 μm or more occupying 70% or more of the total void volume.
Dicarbonated fired material. 4. The carbonized and sintered porous granular paper sludge according to claim 3, which has a major axis of 2 to 8 mm and has a spherical, elliptical, rugby ball or columnar shape.