JP2022142857A - Filler treatment method - Google Patents

Abstract

To suppress a treating cost when treating fillers generated in a dry sand crushing process by using a dewatered cake and the like generated in waste water treatment in a washing aggregate manufacturing process, and to effectively utilize the fillers as a cement raw material.SOLUTION: Provided is a treating method of fillers in which fillers F generated in a dry sand crushing process are granulated and cured by adding ordinary cement CE and water W. In addition, a dewatered cake CA may be added for granulation. Granulation can be ensured by adjusting the water content of filler, ordinary cement and water before granulation or the mixture of filler, ordinary cement, water and dewatered cake before granulation to 9.5 mass% or more and 18.3 mass% or less, and the strength of the granulated material can be sufficiently enhanced by adjusting the addition rate of ordinary cement to the filler, ordinary cement and water before granulation, or to the mixture of the filler, ordinary cement, water and dewatered cake before granulation, to 2.5 mass% or more.SELECTED DRAWING: Figure 1

Description

The present invention relates to a filler treatment method, and more particularly to a method of treating filler generated in a dry sand crushing process using dehydrated cake or the like generated in wastewater treatment in a water-washed aggregate manufacturing process, and using the treated cake as a raw material for cement.

In Patent Document 1, in order to effectively use crushed stone fine powder as a civil engineering material, water purification plant dehydrated cake, blast furnace cement and water are added to crushed stone fine powder, and the blending ratio of dewatered cake is 70 ± 20% by mass, and the blending ratio of blast furnace cement is It is disclosed that these are granulated after setting the ratio to 5 to 10% by mass as an external ratio.

JP 2009-190949 A

However, the invention described in Patent Document 1 has a high blending ratio of dehydrated cake and blast furnace cement, a long curing period of one week, a large amount of water in the granules, and batch granulation, so the processing cost is high. There is a problem that the

Further, the invention described in Patent Document 1 granulates crushed stone fine powder and reuses it mainly as a backfilling material. On the other hand, granules used as raw materials for cement are required to be easily pulverized and have a low water content. However, in the invention described in the document, since the granules are used as a backfilling material or the like, the strength of the granules is high, and it is difficult to use the granules as a raw material for cement.

Therefore, the present invention has been made in view of the above-mentioned problems in the conventional technology, and treats the filler generated in the dry sand crushing process using dehydrated cake etc. generated in the wastewater treatment of the water-washed aggregate manufacturing process. In this regard, the object is to reduce the processing cost and to effectively utilize them as cement raw materials.

In order to achieve the above object, the present invention is a filler treatment method, characterized in that ordinary cement and water are added to the filler generated in the dry sand crushing process, granulated and cured.

According to the present invention, by using ordinary cement instead of blast-furnace cement for granulating the filler, it can be cured for a relatively short time and has a strength to the extent that fine powder does not flow out due to rainwater, and can be used as a raw material for cement. The strength can be such that it can be easily pulverized.

In the method for treating the filler, in addition to the ordinary cement and water, a dehydrated cake generated in the water-washed aggregate manufacturing process may be added for granulation.

In addition, the water content of the filler before granulation, ordinary cement and water, or the mixture of filler, ordinary cement, water and dehydrated cake before granulation is 9.5% by mass or more and 18.3% or less relative to the filler By adjusting according to the addition rate of the dehydrated cake, granulation can be reliably performed.

Furthermore, by adjusting the normal cement addition rate of the filler before granulation, normal cement and water, or the mixture of filler, normal cement, water and dehydrated cake before granulation to 2.5% by mass or more, The strength of the granules can be sufficiently increased.

By installing a second granulator such as a pan pelletizer after the granulator that performs the granulation and performing granulation again, it is possible to cope with the case where a large amount of fine powder is generated by the first granulation. .

For the granules with low water retention that are granulated with the filler before granulation, ordinary cement, and water, water is sprinkled when curing the granules obtained by the granulation, thereby suppressing the hydration reaction of the cement. It is possible to produce a granulated material having a strength capable of replenishing the necessary moisture in and suppressing outflow of the filler due to rainwater.

In addition, the granules or the granules after watering can be used as a raw material for cement.

As described above, according to the present invention, when the filler generated in the dry sand crushing process is treated using the dehydrated cake or the like generated in the wastewater treatment of the washing aggregate manufacturing process, the treatment cost can be kept low and these can be used as cement. It can be effectively used as a raw material.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall configuration diagram showing a configuration example of an apparatus for carrying out a filler processing method according to the present invention; FIG. 10 is a graph showing the relationship between cake addition rate and moisture content of granules in test examples of the filler treatment method according to the present invention, in which the granulation properties are good in the hatched range. Fig. 2 is a graph showing the relationship between the cake addition rate and the cement addition rate in test examples of the filler treatment method according to the present invention, in which the granule strength is good in the hatched range.

EMBODIMENT OF THE INVENTION Next, it demonstrates in detail, referring drawings for the form for implementing this invention.

FIG. 1 shows an example of an apparatus for carrying out the method for treating a filler according to the present invention. This apparatus 1 removes filler (collected dust containing limestone as a main component, etc.) generated in a dry sand crushing process by washing bones with water. When granulated by mixing with dewatered cake, etc. generated in the wastewater treatment of the wood manufacturing process, and stacked in an open-air storage area, even if the granulated material is exposed to rainwater, fine powder will flow out from the granulated material. It is intended to prevent

The apparatus 1 includes a thickener 2 for sedimentation and separation of wastewater in the washing aggregate manufacturing process, a dehydrator 3 for dewatering the slurry S from the thickener 2, a dewatered cake CA from the dehydrator 3, and a dry sand crushing process. A granulator 4 that mixes a filler F, ordinary cement (hereinafter referred to as "cement") CE, and water W to granulate, and the granules G produced by the granulator 4 are cured to increase their strength. It is composed of storage space 5 and the like. Depending on the situation, a mixer for crushing the dehydrated cake CA from the dehydrator 3 and mixing it with the filler F may be provided in the preceding stage of the granulator 4, or a mixer for granulation may be further provided in the latter stage of the granulating machine 4. A pan pelletizer 6 is provided, and a sprinkler device 7 is provided above the place 5. - 特許庁Also, the dehydrated cake CA may not be used for granulation.

A continuous pug mill can be used for the granulator 4 . A pug mill has two shafts provided with a plurality of paddles inside a casing, and these shafts are rotatable. The inclination of the paddle should be between 10 and 45 degrees, and a pin may be used instead of the paddle.

A pug mill can be used as the crushing mixer, and a mixer other than the pug mill can also be used. As an example, a ribbon mixer may be used. The ribbon type mixer removes the conventional shaft, which was an obstacle to mixing, and uses two spiral arms to improve mixing performance.

A batch-type drum-type mixer or the like may be used as the granulator 4 capable of performing from pulverization to granulation in one unit. The drum type mixer is equipped with swing-type blades and multi-stage rotors capable of changing the rotation direction and speed inside the drum. are stirred, uniformly kneaded and granulated.

The pan pelletizer 6 is provided to reduce the fine powder amount of the granules produced by the granulator 4 . The pan pelletizer 6 rolls and granulates the material by tilting the pan. By finely adjusting the number of rotations and the angle of inclination of the pan, granules with an outer diameter of several millimeters to several tens of millimeters are continuously produced. can be obtained by

A sprinkler or the like can be used for the watering device 7, and it is preferable that water is uniformly sprinkled by a fan-shaped watering nozzle or the like, and the watering time is controlled by a timer.

Next, the overall operation of the device 1 having the above configuration will be described with reference to FIG.

A thickener 2 sediments and separates waste water generated in a washing aggregate manufacturing process in a limestone mine, and a slurry S discharged from the thickener 2 is dehydrated in a dehydrator 3 to produce a dehydrated cake CA. This dehydrated cake CA is supplied to the granulator 4 together with the filler F, cement CE and water W generated in the dry sand crushing process, and the granulator 4 crushes, mixes, kneads and granulates the cake. At this time, the amount of water W to be added is the minimum amount required for granulation. If the dehydrated cake CA contains a lot of moisture and exceeds the amount of moisture required for granulation, quicklime may be added to evaporate unnecessary moisture through a digestive reaction. The granules G are piled up in the storage area 5 and cured to have appropriate strength and improved handleability, and are then used as a raw material for cement or the like.

Next, the granulation process when using a pug mill as the granulator 4 will be described in detail.

The filler F supplied to the pug mill has a water content of 0.1 to 2.0% and a d50 (median diameter) of 30 to 70 μm. The water content of the dehydrated cake CA is 17-30%, d50 is 5-20 μm, and a polymer flocculant is added to the dehydrated cake CA in the wastewater treatment process. Ordinary Portland cement (ordinary cement) is used as cement CE. Ordinary cement is preferred because it tends to be strong in a short time compared to the blast-furnace cement described in Cited Document 1. Although new water is used as the water added for granulation, wastewater discharged from the wastewater treatment process (filtrate obtained by dehydrating the slurry S with the dehydrator 3, water after washing the cake, etc.) can also be used. good.

The dehydrated cake CA is introduced into the apparatus from near one end of the pug mill, and the dehydrated cake CA of 100 to 500 mm is pulverized into 3 to 20 mm by the paddles in the process of flowing to near the other end of the apparatus. By pulverizing the dehydrated cake CA first, the mixability with the filler F and the cement CE that are introduced later is improved. Next, the filler F and the cement CE are charged from one end of the device into which the dehydrated cake CA is charged from about 1/4 of the length of the device, and are dry-mixed together with the pulverized dehydrated cake CA. By dry-mixing before adding the water W, it is possible to uniformly disperse the cement CA, which is added in a small amount. Next, water W is supplied from a position about half the length of the apparatus, and 3 to 50 mm granules G are formed by the time the water is discharged from the other end of the apparatus. Thus, by subdividing the inside of the pug mill into the cake crushing zone, the mixing zone, the kneading zone, and the granulation zone, efficient granulation can be achieved.

The raw material filling rate of the pug mill is 10 to 75%, preferably 35 to 55%, and is changed according to the granulation conditions. The residence time is 1 to 20 minutes, preferably 2 to 10 minutes, depending on the granulation situation and the pug mill may be tilted to adjust the residence time. Alternatively, the crushing/mixing zone and the kneading/granulation zone may be divided and connected in series. Thereby, it is possible to set the number of revolutions of the shaft suitable for each zone.

The amount of water that can be granulated varies depending on the addition ratio of the dehydrated cake CA to the filler F. When the addition rate of the dehydrated cake CA is 0%, the water content is 9.5 (lower limit), and when the addition rate of the dehydrated cake CA is 100%, the water content is 18.3% (upper limit). is. Assuming that the cake addition rate is x and the water content of the granules is y, the optimum water content can be obtained from the relational expression y=0.0485x+11.625. The range of moisture that can be granulated is the intercept of the relational expression, 11.625±2. In addition, since the water content of the dehydrated cake CA is 17 to 30%, if the water content exceeds the range of water that can be granulated, quick lime is added to the dehydrated cake CA before granulation to evaporate the water, or It should be dried.

In addition to the water content that can be granulated, the optimum amount of cement also varies with the addition rate of the dehydrated cake CA. In order to achieve sufficient strength in a relatively short curing time, it is necessary to use 3.5% or more cement at a cake addition rate of 0% (filler - 100%), and 2.5% or more cement at a cake addition rate of 25-50%. , at a cake addition rate of 75%, the cement is 3.5% or more, and at a cake addition rate of 100% (filler 0%), the cement is 4.5% or more. From the viewpoint of cost, the cement addition rate is preferably less than 5%. The size of the granules is preferably 2-40 mm, more preferably 5-20 mm. When the granules are sieved through a sieve with a sieve mesh of 0.6 mm, the fine powder ratio is preferably 10% or less, more preferably 6%, and particularly preferably 3% or less. The bulk density of the granules is preferably 0.8-1.6 t/m ³ , more preferably 1.0-1.4 t/m ³ . The angle of repose of the granules is preferably 30-60°, more preferably 40-50°.

Next, various tests for determining the conditions necessary for carrying out the filler treatment method according to the present invention using the apparatus 1 will be described.

Table 1 shows the water content, chemical composition and particle size of Filler F, Cake CA and Cement CE used in the test. Moisture is given by weight and chemical composition is given on a dry basis.

First, in granulating the filler F, it was investigated which of cement CE and quicklime is preferable as a binder to be added together with the cake CA, and what the amount of addition thereof is preferable.

The weight ratio (dry base) of cake: filler: binder is 25:75:0.5 to 3.5, mixed with a Henschel mixer, granulated while adding water to the mixture with a pan pelletizer, and cured for a predetermined time. did. After curing, the granules were immersed in water or sprinkled with water, and the turbidity of the water was used to evaluate the granules according to four levels shown in Table 2.

Granules containing quicklime or cement as a binder were cured for 5 hours and then immersed in water to confirm disintegration properties. Table 3 shows the results. The granules with 2.5% by mass of quicklime as a binder disintegrated immediately after being immersed in water, but the granules with 2.5% by weight of cement as a binder did not disintegrate even after half a day. . Therefore, it can be seen that cement is preferable as a binder.

Next, after setting the cake: filler weight ratio (dry base) to 25:75, the cement addition rate (mass%) and the curing time of the granules were changed, and the granules were treated at a rate equivalent to 50 mm / h. The turbidity of the water was evaluated after 10 minutes of watering. Table 4 shows the results. According to the table, in order to prevent fine powder from being washed out by rainwater from the granules with an addition rate of 25% cake, it is necessary to add 2.5% by mass or more of cement to the granules and cure them for 5 hours or more. I understand.

Next, using cake, filler, and cement, a test was carried out on the outflow evaluation of granules granulated with a pug mill and a pan pelletizer. The weight ratio of cake:filler:cement was 25:75:2.5, and water was added and granulated with a pug mill (150 kg/h). 11.3% by mass) was obtained (pug mill product). The amount of fine powder (under 0.6 mm sieve) of this granulator product was 6.9% by mass. In order to reduce the amount of fine powder, the pug mill product is further granulated with a bread pelletizer to obtain granules of 15 to 30 mm (moisture content: 11.1% by mass) (pane pellet product), and the fine powder amount is 0.0% by mass. became. Thus, by granulating with a granulator such as a pug mill and then granulating with a pan pelletizer as finishing, generation of fine powder can be suppressed. Both the Pugmil product and the Pampere product were good in the water immersion and water sprinkling evaluations.

From the above, it can be seen that when granules are produced from cake, filler, and cement, 2.5% by mass or more of cement should be added as a binder, and the granules should be cured for 5 hours or more.

Next, using a pug mill, the relationship between the amount of water that can be granulated and the amount of cement that develops sufficient strength was investigated when the ratio of cake, filler and cement was changed. Table 6 shows the results. Regarding the granulation properties in the table, ◯ indicates that the water content was appropriate and granulation was possible, and x indicates that the water content was too low and the material did not come together, or the water content was too high and resulted in clay-like lumps. In addition, regarding the strength of the granules, ◯ was given when the above water immersion and water sprinkling evaluations were ⊚, and x was given otherwise. Fig. 2 shows the relationship between the cake addition rate (% by mass) and the water content of the granules (% by mass). Further, in Table 6, the granulation property of Example No. 1 was evaluated as ◯. FIG. 3 shows the relationship between the cake addition rate (mass %) and the cement (binder) addition rate (mass %) for 1 to 14. In both figures, when the granulation property or granule strength is ◯, the case is indicated by a black square, and when the case is x, the case is indicated by a black diamond.

Table 7 shows the lower limit and upper limit of the water content (% by mass) of the granulated product for each cake addition rate (% by mass) based on the above results. If the water content of the granules (% by mass) is between the lower limit and the upper limit, the granulation properties will be good.

Also, in Table 6, No. 1 had good granulation properties but lacked strength. 10 and no. Regarding No. 12, the moisture content after granulation and after curing was compared. As shown in Table 8, No. No. 12 (15% by mass of cake) had a moisture reduction rate of 26% by mass (13.1→9.7% by mass), whereas No. 10 (0% by mass of cake) had a large moisture reduction rate of 91% by mass (12.8→1.2% by mass). As can be seen from Table 1, the filler has less clay components (SiO ₂ , Al ₂ O ₃ ) than the cake, and has a larger particle size, so the water retention is lower. Therefore, when the cake is 0% by mass, the water retention is low and there are voids between the particles. It is presumed that

Therefore, as a result of immersing the granules after watering (curing for 5 hours→curing for 10 hours: curing for a total of 15 hours), improvement in disintegration was observed in all granules. Therefore, when the water content of the granules decreases during curing, it is also effective to sprinkle water with a sprinkler or the like to retain water in the granules.

As described above, according to the present invention, ordinary cement is used in granulating the filler generated from the dry sand crushing process, and the amount of water added during granulation is minimized to produce granules that are easy to crush. By doing so, it is possible to obtain a granule that can be easily used as a raw material for cement. In addition, since the granules have little water content, the heat loss of the cement kiln can be reduced. Since the granules are easily pulverized, the pulverization cost can be reduced. Furthermore, by using a granulator, granulation can be continuously performed, and a large amount of filler can be processed. Furthermore, there is an advantage that the storage space can be reduced by shortening the curing period.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment of the present invention, and various modifications and applications are possible without departing from the scope of the present invention. is.

1 Filler treatment device 2 Thickener 3 Dehydrator 4 Granulator 5 Placement 6 Pan pelletizer 7 Sprinkler CA Dehydrated cake CE Ordinary cement F Filler G Granule S Slurry W Water

Claims (7)

A filler treatment method characterized by adding ordinary cement and water to filler generated in a dry sand crushing process, granulating the granules, and curing the granules. 2. The method of treating a filler according to claim 1, wherein the granulation is performed by adding a dewatered cake generated in the water-washed aggregate production process in addition to the ordinary cement and water. The water content of the filler before granulation, ordinary cement and water, or the mixture of filler, ordinary cement, water and dehydrated cake before granulation is adjusted to 9.5% by mass or more and 18.3% or less. The method for treating a filler according to claim 1 or 2. The normal cement addition rate of the filler before granulation, normal cement and water, or the mixture of filler, normal cement, water and dehydrated cake before granulation is adjusted to 2.5% by mass or more. Item 1, 2 or 3, the filler treatment method. 5. The filler processing method according to any one of claims 1 to 4, wherein a second granulator is installed after the granulator that performs the granulation, and granulation is performed again. 6. The filler treatment method according to claim 1, wherein water is sprinkled when curing the granules obtained by the granulation. 7. The filler treatment method according to claim 1, wherein the granules or the granules after watering are used as raw materials for cement.

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