JP4063963B2 - Manufacturing method of cement products with fibers - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention circulates and uses fiber discharged from a paper machine and white water containing cement in the manufacturing process of fiber-containing cement products such as asbestos slate and slate board, and maintains the activity of cement in sludge water even after the operation is stopped. The present invention relates to a method for producing a fiber-containing cement product to be used on the next day or later.
[0002]
[Prior art]
White water containing fiber and cement is discharged in a cement product manufacturing plant such as a slate board. A method of using this white water as part of a slate papermaking slurry has been conventionally performed. However, sludge water that cannot be reused was discarded because the product gradually became whitish during continuous operation and the quality deteriorated. In addition, after suspending work such as at night, the hydration of the cement proceeds and the loss on ignition of the cement is 15% or more. If this is used, the quality of the product will deteriorate, so it will be concentrated and dehydrated and disposed of industrially. It was processed as a thing.
[0003]
[Problems to be solved by the invention]
It is preferable to use a setting retarder in order to maintain the cement without losing the ignition loss even during the period when the work is not performed. There has been a demand for a technique for producing an excellent product by suppressing the generation of industrial waste by using as small a setting retarder as possible. For this purpose, a technology that adds a setting retarder at the most efficient site, measures the loss on ignition of cement in sludge water in a short period of time, and adds the minimum required amount of setting retarder without excess or deficiency. Was necessary.
[0004]
[Means for Solving the Problems]
An object of the present invention is to solve the above-mentioned problems, and the constitution thereof is to produce a fiber-containing cement product by making a raw material slurry containing fibers, cement and water, and the fibers and cement discharged from the paper making process. The sludge water contained is primarily stored in the drainage tank, then transferred to the pulper, added with other materials by the pulper, and reused as a raw material slurry in the papermaking process. It is characterized by using added fresh water. Furthermore, by adding a coagulation retarding agent that is all or part of glucose and adsorbing a reagent that exhibits a color reaction that can be visually recognized within 10 minutes by reacting with glucose, It is characterized by measuring the activity of cement in sludge water and adjusting the amount of setting retarder added.
[0005]
The time required for one cycle of slurry preparation in the pulper-paper making process-drainage tank storage-again slurry preparation in the pulper is about 2 hours. The present inventors have found that the loss on ignition of the wastewater generated in the process of drawing the slurry on a net and dewatering is approximately 1% or less regardless of the loss on ignition of the raw slurry. This is because in the papermaking process, large cement particles that have been hydrated are trapped when passing through a mesh or a high-concentration slurry layer during papermaking, and cement with a small hydration ratio is released into the wastewater. It is thought that. At the end of the rotor located at both ends of the round net type rotor row of the paper making machine, soot accumulates and is constantly washed with running water, but the present invention adds a setting retarder to this washing water. It is intended to improve the use efficiency of the setting retarder by reducing the loss on ignition of the waste water.
[0006]
Furthermore, if the ignition loss of cement in sludge water can be easily measured at any part of the entire process of slate production, the setting retarder can be added without excess or deficiency, and the maximum effect can be achieved with the smallest amount. Obtainable.
The present invention uses a reducing sugar for a part or all of the setting retarder, and immerses a filter paper adsorbing a reagent that reacts with the reducing sugar and shows a color reaction that can be visually recognized within 10 minutes. , And successfully added a setting retarder without excess or deficiency.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The fiber in the present invention is not particularly limited, and organic fibers such as vinylon and pulp and inorganic fibers such as asbestos are generally used. Similarly, the cement is not limited, and what is generally called a hydraulic substance such as ordinary Portland cement and silica cement can be used.
The retarder used in the present invention includes oxycarboxylic acid compounds such as gluconic acid, citric acid and tartaric acid or salts thereof, sugars such as glucose, sucrose and lactose, and aminophosphonic acids such as aminotrimethylenephosphonic acid. All compounds having a promoting effect on cement such as siliceous compounds and salts thereof, lignin sulfonic acid or its salt-based water reducing agents, which have no accelerating action, and silicic fluorides are included.
[0008]
As shown in FIG. 1, a flow sheet showing the circulation of cement-containing sludge water in a fiber-containing cement manufacturing plant is obtained by chest mixing a slurry obtained by thoroughly mixing water, cement, fiber and admixture in an appropriate ratio in a pulper 1. Send to. The slurry in the chest 2 is sent to the papermaking machine 3 to produce the slate plate 4. Since the slurry in the papermaking machine 3 is made up of solids by the rotor 8, the slurry gradually dilutes and is continuously discharged. The discharged sludge water contains cement and fibers and is white and cloudy, so it is also called white water. The sludge water is stored in the drain tank 5 and sent to the pulper 1 again to replenish other components 13 such as cement, fiber, water and the like, and sent to the chest 2 after adjusting to an appropriate concentration. The time required for one cycle of sludge water containing cement to circulate is about 2 hours. In general, the sludge water is circulated even if there is a slight deterioration in quality.
[0009]
However, since the work is not performed at night, the sludge water in the drainage tank 5 is stored in the sludge water tank 6 after the work is completed. The cement in the sludge water tank 6 is hydrated, and the ignition loss on the next morning is generally 15 to 20%. When the ignition loss is high, the function as a cement is almost lost and the strength of the product is remarkably deteriorated, so the solid content must be concentrated and discarded as industrial waste. If a set retarder is added to the sludge water tank 6 and gently stirred, it can withstand use from the next day.
[0010]
The type of the papermaking machine 3 is not particularly limited, but in any case, sludge water is generated. In FIG. 1, a round net type paper machine is shown. Slurry is supplied into the slurry tank 7 and the rotor 8 is rotating. Although four rotors 8 are shown in FIG. 1, the number of rotors is not limited. Reference numeral 9 denotes an endless belt made of a net material, and felt or the like may be further laid. The rotor 8 rotates to pick up the fibers and cement in the slurry and adhere them to the outer periphery of the endless belt 9. Each time the endless belt comes into contact with the rotor, the thickness of the attached slurry layer increases and reaches about 0.3 to 0.75 mm.
[0011]
The moisture in the slurry layer 11 gradually decreases on the endless belt 9 until the last contact with the making roll 10 after the last contact with the rotor 8d. The slurry layer dewatered to the extent that it can be formed in the making roll 10 is separated from the endless belt 9 and wound around a plurality of layers around the outer periphery of the making roll 10, and when reaching a certain thickness, the slate plate 9 is moved away from the making roll 10. Form. Therefore, no slurry component adheres to the endless belt 9 between the making roll 10 and the first rotor 8a.
[0012]
In general, since soot adheres to the making roll 10 side of the first rotor 8a and the chest 2 side of the last rotor 8d, the rotor cleaning water 12 is sprayed from the direction indicated by the arrows with a nozzle for cleaning. It is preferable that the rotor wash water by adding a retarder to the fresh water.
After dehydration, the film is wound around the making roll 10 to a predetermined thickness, cut into a sheet, the corrugated product is formed by a molding machine, and the flexible plate is pressurized at 120 to 150 kg / cm ² . Next, it is cured and cured to obtain a product. After the sheet is formed, the ear is cut to adjust the shape. The cut ear can be returned to the pulper 1 and reused as a raw material.
[0013]
The present inventors have found that the ignition loss of sludge water discharged from the papermaking machine 3 is approximately 1% regardless of the ignition loss of the raw slurry. Therefore, if the setting retarder of 0.01 to 0.1% (in terms of solid content) is added to the rotor cleaning water 12 that joins the fresh drainage with the least amount of set retarder consumption, the setting retarder is most effectively used. Thus, a homogeneous and high-strength product can be obtained throughout the entire process, and the sludge water stored in the sludge water tank 6 after the operation can be used as it is as a part of the raw material. Alternatively, the setting retarder may be added to the sludge water tank 6 after the operation is completed without adding the setting retarder during the operation.
[0014]
The reducing sugar used in the present invention is a monosaccharide, disaccharide or oligosaccharide having reducing properties, such as glucose, fructose, lactose, maltose, and invert sugar. These reducing sugars have various detection methods utilizing their reducing properties.
For example, in the enzyme method, an oxygen absorption amount or hydrogen peroxide produced is detected by a biochemical or chemical method using an enzyme such as glucose oxidase or galactose oxidase. Among them, glucose produces hydrogen peroxide by the action of glucose oxidase, then oxidizes o-tolidine by the action of peroxidase, and changes its color from yellow to blue depending on the glucose concentration. This reaction is sensitive and can be detected in a short time and is specific for glucose.
[0015]
In addition, the Beringlan method in which the Fe 2 solution is added to the test solution and heated, and Cu ₂ O that precipitates according to the amount of reducing sugar is titrated with a standard solution of H ₂ SO ₄ acidic permanganate, CuSO ₄ is alkaline and reduced Cu ₂ O produced by reduction with sugar consumes I ₂ liberated as KIO ₃ + KI under acidic conditions. Titration of residual I ₂ with Na ₂ SO ₃ or coloration with starch solution, titration of a certain amount of boiling falling solution with reducing sugar solution using methylene blue as an internal indicator, and determination of rain-einone saccharide The Rain-Ainon method or the optical rotation method for calculating the amount of sugar by using can be utilized.
[0016]
Being visible in the present invention means a method that can be determined with the naked eye without using a special instrument. Therefore, the color reaction is preferable because the presence of reducing sugar can be reliably determined. However, all reactions involving changes that can be determined with the naked eye, such as the occurrence of turbidity, increased transparency, and changes in the surface state, are included in addition to the color reaction.
The most preferable method is to adsorb the reagent in advance, such as filter paper, and immerse the filter paper in sludge water, and determine by coloration or other changes when reducing sugar is present. Since the change that can be visually recognized is an on-site work, complicated things are not practical and can be determined within 10 minutes, preferably within 5 minutes, and more preferably within 3 minutes.
Not only the method of immersing the test paper, but also a method that can be determined by placing test water in a glass tube and dropping the reagent, such as a residual chlorine meter in the field, can be preferably used.
[0017]
【Example】
As a glucose detection reagent, a test paper for detecting glucose in urine was used which was obtained by impregnating a filter paper with a solution in which 450 units of glucose oxidase, 14 units of veroxidase and 8.4 mg of o-tolidine were mixed and dried. The minimum detection sensitivity of this test paper was 30 mg / dl of glucose, and determination was made 30 seconds after immersion in sludge water.
When the loss on ignition was about 5% or less which can be reused as cement, the test paper turned blue and was detectable. When the ignition loss exceeded 10, no reaction occurred and no detection was possible.
[0018]
The loss on ignition of sludge solids can be obtained by measuring the loss on ignition of the fiber alone and subtracting it from the overall loss on ignition. Alternatively, the acid-insoluble matter can be measured and the fiber ratio can be confirmed in advance to correct the numerical value. The loss on ignition was measured by filtering sludge water with suction, washing the filtrate with acetone and repeating suction filtration, and drying at 105 ° C. until a constant weight was obtained. This sample was measured in accordance with JIS R 5202 (chemical analysis method for Portland cement) ignition loss analysis method.
Measurement of the loss on ignition of sludge solids requires time and skill, and is impossible to handle in the slate factory. The method of blending glucose as a setting retarder, detecting the presence or absence of glucose, and indirectly determining the loss on ignition of cement is extremely effective for on-site implementation.
[0019]
Example 1
The setting retarder adjusted to 15% by weight of water-containing crystalline glucose (manufactured by Sanei Saccharification Co., Ltd.) and 20% by weight of sodium gluconate (manufactured by Fujisawa Pharmaceutical Co., Ltd.) in sludge water with a solid content concentration of 10% by weight charged into the sludge water tank 6 the night before The solution was added in an amount of 0.3% by volume to the 10% by weight sludge water, and the mixture was gently stirred and mixed. The next morning, when judged with the above test paper before the start of work, it turned pale blue. The ignition loss in this case was 3.5%.
When the loss on ignition was 5% or less, it was detectable because it slightly changed to blue. At this level, the quality of the product was not adversely affected.
On the other hand, when the setting retarder solution was not added to the sludge water tank, the test paper did not change the color in the next morning even when stirring was performed in the same manner, and detection was impossible. The measured loss on ignition was 16.7%.
[0020]
Example 2
0.05% by volume of the setting retarder solution of Example 1 was added to the rotor cleaning water 12 sprayed from the arrow of the papermaking machine 3 in FIG. In this case, the quality of the product did not deteriorate throughout the entire work time. After the completion of the work, the sludge water was transferred to the sludge water tank 6 and gently stirred as it was. The next morning, when the test paper of Example 1 was used for the test, the color turned faintly blue, so it was sent to the pulper 1 and used as a part of the raw material. The ignition loss at this time was 4.9%.
On the other hand, when the setting retarder was not added to the rotor cleaning water, the quality decreased slightly during the operation, but the operation was continued as it was. After completion of the work, the sludge water was transferred to the sludge water tank 6 and stirred in the same manner, but the ignition loss in the next morning was 16.8, and the solid content was settled, dehydrated and discarded.
[0021]
Example 3
The operation was started in the same manner as in Example 2 except that the amount of the setting retarder in Example 1 added to the rotor washing water 12 was 0.02% by volume. The amount of glucose in the slurry in the chest was intermittently detected with the test paper of Example 1, and when the coloration could not be detected at all, the addition amount of the setting retarder was gradually increased. As a result, no quality degradation was observed during the work. Even after the work was completed, the sludge water in the sludge water tank 6 could be used as a part of the raw material of the next day only by slowly stirring without adding a setting retarder. At the same time, the amount of setting retarder used could be significantly reduced.
[0022]
【The invention's effect】
According to the present invention, in any part of the sludge water circulation process of the fiber-containing cement product, the maintenance of the plant becomes easy by grasping the activity of the cement and calculating the necessary minimum amount of the setting retarder to be added. At the same time, all of the raw material cement and fiber can be used effectively.
[Brief description of the drawings]
FIG. 1 is a flow sheet showing circulation of cement-containing sludge water in a fiber-containing cement manufacturing plant.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pulper 2 Chest 3 Paper machine 4 Slate board 5 Drain tank 6 Sludge water tank 7 Slurry tank 8 Rotor 9 Endless belt 10 Making roll 11 Slurry layer 12 Rotor washing water 13 Other components

Claims (3)

A raw material slurry containing fiber, cement and water is made to produce a fiber-containing cement product. Sludge water containing the fiber and cement discharged from the paper making process is primarily stored in a drainage tank and then transferred to a pulper. In the process of adding other materials with a pulper and reusing it as a raw material slurry in the papermaking process,
Activity of cement in sludge water using a reagent that exhibits a color reaction that can be visually recognized within 10 minutes by adding a setting retarder that is all or part of a reducing sugar at any site and reacting with the reducing sugar Is measured, and the addition amount of a setting retarder is adjusted, The manufacturing method of the fiber-containing cement product characterized by the above-mentioned.   2. The method for producing a fiber-containing cement product according to claim 1, wherein fresh water added with a setting retarder is used as washing water for the rotor in the paper making process.   The method for producing a fiber-containing cement product according to claim 1 or 2, wherein the reducing sugar is glucose and the reagent is a reagent comprising glucose oxidase, peroxidase and o-tolidine.

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