Manufacturing method for grinding material

Abstract

To provide a manufacturing method for a grinding material that is manufactured in wet state without being dried.SOLUTION: A manufacturing method for a grinding material comprises a step of preparing coal ashes, a step of supplying water to the coal ashes to stir the ashes, a step of classifying the coal ashes supplied with water and stirred, and a step of packing the classified coal ashes. In the step of packing the coal ashes, the coal ashes are packed in a wet state.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an abrasive used in wet particle slaking blasting.

Background Art

[0002] Conventionally, for a painted surface coated on a steel structure such as a bridge, a blasting method is known in which an abrasive containing sand is sprayed by compressed air to remove rust and an old paint film and to clean the surface of the steel material.

[0003] The blasting method is generally classified into air blasting, vacuum blasting, and wet blasting. Among these, wet blasting is a method in which water and an abrasive are mixed and blasted, and in recent years, it has been increasingly used because of the advantage of less generation of dust.

[0004] For example, Patent Document 1 discloses a blasting material for wet blasting in which alumina, garnet, silica sand, glass beads, silicon carbide, or slag as an abrasive contains 5 to 30% by mass of moisture and is adjusted in advance so that all abrasive particles are wetted.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] As abrasive materials, ferronickel slag, fused alumina, almandite garnet, copper slag, and steel grit are known. However, these conventional blasting materials are mixed with water immediately before the blasting process, and the abrasive materials themselves were not manufactured in a wet state. That is, since the conventional abrasive materials were subjected to a dryer during the manufacturing process, there were problems such as the need for time-consuming drying and the generation of dust.

[0007] Therefore, an object of the present invention is to provide a method for manufacturing an abrasive material that is manufactured in a wet state without drying.

Means for Solving the Problems

[0008] To achieve the above object, the method for manufacturing an abrasive material of the present invention includes a step of preparing fly ash, a step of adding water to the fly ash and stirring, a step of classifying the fly ash that has been added with water and stirred, and a step of packing the classified fly ash in bags.

Effects of the Invention

[0009] Thus, the method for manufacturing an abrasive material of the present invention includes a step of preparing fly ash, a step of adding water to the fly ash and stirring, a step of classifying the fly ash that has been added with water and stirred, and a step of packing the classified fly ash in bags. With such steps, it is possible to manufacture an abrasive material while keeping the raw material fly ash in a wet state without drying it.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the components described in the following examples are illustrative, and are not intended to limit the technical scope of the present invention thereto.

[0012] (Manufacturing System for Abrasive Material) First, the overall configuration of the manufacturing system S for abrasive material will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, the manufacturing system S for abrasive material mainly includes a dissolving tank 10 that receives coal ash as a raw material and is supplied with water and agitated, a wet two-stage vibrating sieve 11 for classifying the pumped coal ash, a lower water tank 12 that receives the fine particles and water that have passed through the vibrating sieve 11, and a dehydration tank 13 that houses a dehydration bag 13a that receives the fine particles and water pumped from the lower water tank 12.

[0013] The dissolving tank 10 is, for example, a cylindrical container, and coal ash (clinker ash or IGCC slag) as a material before classification and water are charged and stored (steps S1, S2). Further, by rotating the stirring blade 10a by a motor 21 installed on the dissolving tank 10, the coal ash and water are kneaded (step S3). Here, the ratio of the material before classification to water in the dissolving tank 10 can be, for example, about 1:3.

[0014] The dissolving tank 10 is configured to maintain a certain amount of water by circulating overflow water from the dehydration layer 13 described later. Note that the size (diameter and height) of the dissolving tank 10 is preferably set according to the processing amount. Specifically, it is necessary to maintain the water surface so that it does not become lower than the stirring blade 10a so that the material before classification and water can be easily kneaded.

[0015] Here, as the coal ash prepared in this embodiment, it is preferable to use clinker ash (CA) or IGCC slag. Clinker ash (CA) is the ash obtained by collecting the lumps of coal ash that have fallen to the bottom of the boiler among the coal ash generated when coal is burned, and dehydrating and pulverizing them. IGCC slag (coal gasification slag) is a glassy slag generated as a by-product in integrated gasification combined cycle (IGCC).

[0016] The dissolving tank 10 and the wet vibrating screen 11 are connected by piping, and a slurry-like mixture of the material before classification and water is pumped from the dissolving tank 10 to the vibrating screen 11 by a pump 22 (step S4).

[0017] The vibrating screen 11 as a wet classifier is a two-stage type composed of an upper screen 11a and a lower screen 11b. By vibrating the upper screen 11a and the lower screen 11b with a motor (not shown), a mixture of wet coal ash and water can be sorted according to the particle size. In this embodiment, a screen (sieve) with a first particle size of 2.0 mm is used as the upper screen 11a with a coarse mesh, and a screen (sieve) with a second particle size of 0.3 mm is used as the lower screen 11b with a fine mesh. Note that if the vibrating screen 11 selects appropriate specifications such as the shape and inclination of the vibrating surface, draining in the next process can also be omitted.

[0018] Therefore, a mixture of coal ash and water with a particle size of 2.0 mm or more (2.0 mm or more material) remains on the upper screen 11a with a coarse mesh (step S5), and the fine mixture of coal ash and water with a particle size of less than 2.0 mm that has passed through the upper screen 11a is further screened by the lower screen 11b in the lower stage (step S6).

[0019] Since the material of 2.0 mm or more remaining on the upper screen 11a is not suitable as a grinding material and is not used, it is collected after being stored in a flexible container bag (step S11).

[0020] On one side, on the fine lower screen 11b, there remains a kneaded mixture of fly ash and water with a particle size of less than 2.0 mm and not less than 0.3 mm (0.3 mm to 1.9 mm material) (step S6). The finer kneaded mixture of fly ash (fine fraction) and water with a particle size of less than 0.3 mm that has passed through the lower screen 11b is received in the lower water tank 12 (step S7).

[0021] That is, the 0.3 mm to 1.9 mm material is bagged while in a wet state and used as an abrasive. As will be described later, the kneaded mixture of fly ash and water bagged while in a wet state is preferably used in wet particle slurring blasting while in a wet state (step S12).

[0022] The lower water tank 12 and the dehydration tank 13 are connected by a pipe, and the material less than 0.3 mm is pumped from the lower water tank 12 to the dehydration tank 13 by a pump 23 (step S8). Thereafter, the material less than 0.3 mm is put into a dehydration bag 13a arranged in the dehydration layer 13 and dehydrated.

[0023] And the water that has come out of the dehydration bag 13a in the dehydration layer 13 is pumped back to the dissolution tank 10 by a pump 24. In this way, the overflow water of the dehydration tank 13 is circulated and reused.

[0024] (Wet particle slurring blasting) Next, with reference to FIG. 3, the configuration of the wet particle slurring blasting device T will be described. The wet particle slurring blasting device T mainly includes a water tank 31 for storing water, a built-in pump 32 that sucks water from the water tank 31 and pumps it to a pressurized tank 33, a pressurized tank 33 to which water and an abrasive from the water tank 31 are supplied, an external compressor 34 for injecting the abrasive (wet particle slurring abrasive) wrapped in water, and a nozzle 35 for injecting the wet particle slurring abrasive in a cyclone shape.

[0025] By using the wet particle slurring blasting device T in this way, the abrasive can be wet particle slurried by pressurizing the inside of the pressure tank 33. That is, the abrasive is wrapped in water and becomes a wet particle slurried state. And when this wet particle slurried abrasive is discharged from the nozzle 35 and collides with the steel surface, the film of water that wrapped the abrasive can sweep while wrapping the paint together.

[0026] In particular, according to the method for manufacturing the abrasive of the above-described embodiment, since the abrasive is manufactured in a wet state, the abrasive and moisture have already become familiar with each other in advance, and it is easier to maintain the wet particle slurried state. That is, at the time when the abrasive is charged into the pressure tank 33, since the abrasive already holds moisture, the moisture and the abrasive are efficiently kneaded in the pressure tank 33 and are easily wet particle slurried. In addition, since the abrasive is already in a wet state holding moisture, the amount of water supplied to the pressure tank 33 can be reduced.

[0027] The wet particle slurring blasting method using this wet particle slurring blasting device T has the following technical features and effects. 1) By specifying the material type, particle size, and Mohs hardness of the non-metallic abrasive, the quality of one kind of keren specification can be ensured. 2) By selecting the mixing ratio of water and the abrasive, visibility is ensured by suppressing dust and preventing the scattering of harmful substances, etc., and the safety of the work is improved. Furthermore, the removal of surface deposits containing salt can be carried out simultaneously with the substrate adjustment. 3) By adopting a vaporized water-soluble rust preventive agent, the return rust can be prevented.

[0028] In this way, by using this wet particle slurring blasting device T, the abrasive covered with a film of water wraps the paint, rust, and harmful substances when colliding with the surface of steel or the like, thereby suppressing dust and preventing scattering, and at the same time, the removal of adhering salts that is difficult to remove by the conventional dry blasting method can be carried out, and the treatment in one step becomes possible. Furthermore, as a substrate adjustment method aiming at using one kind of high-quality keren, the scraping off of lead-containing paint films, which has been a problem in recent years, can also be surely carried out in a wetted state.

[0029] More specifically, the wet particle slaking blasting method using the wet particle slaking blasting device T also has the following effects.

[0030] · Dust generation can be suppressed with compact mechanical equipment In the conventional dry blasting method, since the scattering of non-metallic abrasives and crushing dust are intense, large-scale equipment such as dust collection devices, temporary dust protection facilities, ventilation and air exchange facilities, and lighting devices are required during operation. In contrast, the blasting method using wet particle slaked abrasives can use compact mechanical equipment and suppress dust generation, and is excellent in terms of cost and hygiene.

[0031] · Compatible with rust preventive primer treatment Since a vaporized water-soluble rust preventive agent is applied, it is possible to ensure the quality up to the rust preventive primer treatment of the grinding surface. The application of the vaporized water-soluble rust preventive agent suppresses the occurrence of return rust and protects the steel surface up to the rust preventive primer treatment, so the quality within 4 hours determined in the steel road bridge corrosion prevention manual can be ensured.

Example

[0032] Next, with reference to FIGS. 4 to 6, an applicability confirmation test carried out to confirm the particle size of the abrasive suitable for the wet particle soil blasting equipment will be described. In this applicability confirmation test, for clinker ash and IGCC slag, abrasives with two types of particle sizes are created respectively. Then, the effects are confirmed in the blasting test using the created abrasives. The particle sizes of the abrasives are the following two types.

[0033] · Clinker ash: 1) 0.3 mm to 1.9 mm, 2) 1.9 mm or less · IGCC slag: 1) 0.3 mm to 1.9 mm, 2) 1.9 mm or less

[0034] In the production of abrasives, an efficient classification system is selected, and the classification effect and quality are confirmed by indoor tests before and after classification. As described below, a wet classification system is selected as the manufacturing method of abrasives suitable for the wet particle slaking blasting equipment.

[0035] (1) Grinding material processing The clinker ash and IGCC slag generated in the power plant were processed into wet grinding materials. In the current confirmation test of the suitability of the grinding material by blasting, since both the clinker ash and IGCC slag were carried out in two cases of grinding material particle sizes of 0.3 mm to 1.9 mm and 1.9 mm or less, for the preparation of the grinding material of 0.3 mm to 1.9 mm (first-stage classification), the two-stage vibration sieve 11 was selected, and screens with an upper stage of 2.0 mm and a lower stage of 0.3 mm were installed. For the preparation of the grinding material of 1.9 mm or less in the second-stage classification, it was planned to use a kneader to mix and stir a predetermined amount of the material less than 0 to 0.3 mm generated in the first-stage classification with the first-stage classification material to prepare the grinding material.

[0036] (2-1) First-stage classification (2-2) Classification flow Using Figures 1 and 2, the equipment and processes as described above are used.

[0037] (Discussion) Due to selecting a compact and simple wet vibration sieve 11 for the trial system, water drainage and dehydration were insufficient when the material was screened and moved. When directly packed in plastic bags, it became overly wet, so it was packed in sandbags, and after dehydration for a predetermined time, the outside was sealed with a plastic bag.

[0038] If the appropriate specifications such as the shape and inclination of the vibration surface of the vibration sieve 11 are selected, water drainage in the next process can be omitted, and the bagging efficiency can be improved.

[0039] The ratio of the material to water in the dissolution tank 10 was set to 1:3. Although it was planned to circulate the overflow water, tap water was used in the first half because there was little overflow water. Since the amount of water in the dissolution tank 10 was small during the process, the material separated and clogging occurred. In the second half, by circulating the overflow water, sufficient kneading was carried out, and the material could be smoothly pumped.

[0040] The relatively large shape and dimensions of the dissolution tank 10 also contributed to material separation during a small amount of dissolution (kneading of water and material). In addition, it was necessary to constantly add water in accordance with the state so that the water surface would not drop below the stirring blade 10a. Therefore, it is necessary to select a dissolution tank 10 with an appropriate shape, size, and specifications.

[0041] The underlayer material is pumped together with the surplus water to the dehydration tank 13 at 5m 3 and dehydrated by the dehydration filter 13a. At this time, fine-grained norovirus flows out of the surplus water from the dehydration filter 13a. Therefore, in the initial stage of surplus water storage, the turbidity is high. However, the norovirus of clinker ash and IGCC slag settles quickly in water, and the supernatant water becomes about SS200 or less the next day, enabling drainage that complies with the sewage discharge standard (less than SS600). In order to reduce the drainage volume, the recycling of surplus water is also important.

[0042] The time required to create a windbag by the wet vibrating sieve machine 11 this time was about 30 seconds to 1 minute 30 seconds per bag, although it also depended on the adjustment of the pumping volume according to the situation by the inverter pump.

[0043] (2-3) Classification results of the first process The particle size composition of the materials and the first-process classified materials transported to the Dairi Construction Technology Research Institute was confirmed by a simple sieving test in the laboratory. Also, the unit volume weight and water content ratio were similarly confirmed by laboratory tests.

[0044] As shown in Fig. 4(a), the particle size distribution shows that for the clinker ash before classification (the transported material), 6.7% of the oversize material was 2.0 mm or more, while for the first-classified material, it was 1.0%. Also, for the IGCC slag before classification (the transported material), 21.4% of the undersize material was 0.25 mm or less, while for the first-classified material, it was 1.3%. That is, for clinker ash, mainly oversize material is separated by the first-process classification, and for IGCC slag, mainly undersize material is separated by the first-process classification and the particle size is adjusted.

[0045] The unit volume weight, as shown in Fig. 4(b), was measured before classification (incoming material), and the clinker ash was 0.852 g / cm 3 and the IGCC slag was 1.853 g / cm 3 .

[0046] As shown in Fig. 4(c), the water content ratio of the first classified material of the clinker ash was 35.6%. Also, the water content ratio of the first classified material of the IGCC slag was 2.2%.

[0047] (3-1) Second-stage classification The following classification was carried out on the first-stage classified material to produce abrasive materials.

[0048] (3-2) Second-stage classification of clinker ash To remove the undersize material less than 0 to 0.3 mm from the first-stage classified abrasive material, reclassification was carried out to produce abrasive materials of 0.3 to 1.9 mm.

[0049] · Equipment used Hand mixer, 18 L pale can, 0.3 mm sieve mesh (used in a wet vibrating sieve machine)

[0050] · Classification procedure 1) Divide the first-stage classified material into four parts (about 5 kg) and put it into a pale can. 2) Add water (abrasive material: water = 1:2) 3) Mix and stir with a hand mixer (1 minute) 4) Discharge onto a 0.3 mm sieve 5) Collect the classified material 6) Repeat steps 1)-6) four times and pack in burlap bags for dehydration 7) Repeat the above steps 1)-6) to make 3 bags (about 60 kg)

[0051] (3-3) Second-stage classification of IGCC slag The undersize material less than 0 to 0.3 mm was kneaded into the first-stage classified abrasive material to produce abrasive materials of 1.9 mm or less.

[0052] · Mixing amount From the particle size test results before IGCC classification (Figure 4(a)), Less than 2 mm: 92.1%, less than 0.25 mm: 21.4% From the particle size test results after IGCC classification (Figure 4(a)), Less than 0.25 mm: 1.3% Therefore, the material less than 0.25 mm in 25 kg of the sample requires 25 kg × (21.4% / 92.1% - 1.3% / 100%) ≈ 6 kg

[0053] · Materials and equipment used Material: IGCC slag underflow material less than 0 - 0.3 mm that settled in the lower water tank 12 of the wet vibrating sieve 11 Equipment: Kneader

[0054] · Mixing procedure 1) Prepare 19 kg of the first-stage grinding material (0.3 mm - 1.9 mm) and 6 kg of the underflow material (less than 0 - 0.3 mm). 2) Manually knead the above materials simply, then put them into the kneader and mix and stir automatically. 3) Open the door at the bottom of the kneader, temporarily receive it in a container, and then pack it in sandbags. 4) Repeat the above steps 1) - 3) to make 3 bags (about 75 kg).

[0055] (Discussion) · When preparing the IGCC slag into a grinding material of 1.9 mm or less by wet classification, if a two-stage vibrating sieve (11) like the first-stage classification is used, the underflow material cannot be retained and stays in the lower water tank 12 together with the excess water after passing through the sieve. This time, the retained underflow material was added and kneaded, but it is not efficient. Therefore, for example, if it is effective in classification by a 2.0 mm sieve in one stage after material grinding (in a wet state), it is considered efficient.

[0056] (3 - 4) Classification results of the second stage Regarding the effect of reclassification of the clinker ash, as a result of conducting a sieving test, as shown in Figure 5, a high separation effect on the clinker ash was confirmed by the dissolution method using a hand mixer. For the IGCC slag, since a predetermined amount was mixed in, the test was omitted.

[0057] (4) Confirmation of the particle size of abrasive suitable for wet granular soil blasting equipment As the confirmation of the particle size of the abrasive suitable for wet granular soil blasting equipment, two cases were considered: one with a particle size range similar to that of the finished product and the other including the undersize material. Using a 1 m × 1 m black-plated iron plate and the center materials (coating film) in the Daito Construction Technology Research Institute as test specimens, a blasting test construction was carried out using the classified abrasive.

[0058] (Discussion) All evaluations as abrasive for blasting satisfied the quality of Sa1 1 / 2 in the paint stripping standard. Regarding the construction efficiency, since the clinker ash is porous and softer than the IGCC slag, the construction time was long and the efficiency was low.

[0059] As shown in Figure 6, regarding the results due to the difference in the particle size range, in both the case of clinker ash and IGCC slag, the case including the undersize material had a shorter construction time. The material consumption per construction area was almost the same. It is presumed that this is because, since the pressure setting etc. was not changed, the fluidity was improved by including the undersize material, and the blasting injection amount per unit time increased.

[0060] (Effect) Next, the effects of the manufacturing method of the abrasive of the present embodiment will be listed and explained. (1) As described above, the manufacturing method of the abrasive of this example includes a step of preparing coal ash, a step of adding water to the coal ash and stirring, a step of classifying the coal ash added with water and stirred, and a step of bagging the classified coal ash. With such steps, it is possible to manufacture the abrasive in a wet state without drying the raw material coal ash.

[0061] (2) Also, in the step of bagging the coal ash, since the coal ash is bagged while in a wet state, it is possible to suppress dust generation during the manufacturing process, and it is also possible to suppress dust generation when using the coal ash adjusted as an abrasive. Furthermore, when used in the wet particle slurring blasting device T, it can better blend with moisture and reduce the amount of water used.

[0062] (3) Furthermore, in the step of classifying the coal ash, by using a two-stage vibrating sieve 11 composed of an upper sieve 11a and a lower sieve 11b as a wet classifier, an oversize material coarser than a predetermined first particle size and an undersize material finer than a second particle size smaller than the first particle size are removed. Therefore, it is possible to efficiently and accurately perform particle size adjustment.

[0063] (4) Also, in the step of classifying the coal ash, it is also preferable to use a one-stage vibrating sieve 11 composed only of the upper sieve (11a) as a wet classifier so that an oversize material coarser than a predetermined first particle size is removed. In this way, it is possible to more efficiently and accurately perform particle size adjustment.

[0064] (5) Also, as for the coal ash, through a confirmation test using clinker ash, it was confirmed that clinker ash, which was not conventionally used as an abrasive, can be newly used as an abrasive.

[0065] Since the water content ratio of this classified clinker ash is greater than 30%, it can better blend with moisture and reduce the amount of water during use.

[0066] (6) Also, as for the coal ash, through a confirmation test using IGCC slag, it was confirmed that IGCC slag, which was not conventionally used as an abrasive, can be newly used as an abrasive.

[0067] Since the water content ratio of this classified IGCC slag is less than 5%, it can better blend with moisture while reducing the weight during transportation.

[0068] In addition, since the other configurations and operational effects are substantially the same as those of the above-described embodiment, the description thereof will be omitted.

[0069] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes that do not deviate from the gist of the present invention are included in the present invention.

[0070] For example, in the embodiment, the case where clinker ash and IGCC slag are used as the coal ash that is the raw material of the abrasive has been described. However, the present invention is not limited to this, and the manufacturing method of the abrasive of this embodiment can also be applied to other types of coal ash.

Explanation of Reference Numerals

[0071] S Manufacturing system of abrasive 10 Dissolution tank 10a Stirring blade 11 Vibration sieve 12 Lower water tank 13 Dewatering tank 13a Dewatering bag 21 Motor 22 - 25 Pumps T Wet particle slurring blasting device 31 Water tank 32 Built-in pump 33 Pressure tank 34 External compressor 35 Nozzle

Claims

1. A step of preparing coal ash; A step of adding water to the coal ash and stirring; A step of classifying the coal ash that has been added with water and stirred; A step of bagging the classified coal ash; A method for manufacturing an abrasive, comprising the above steps.

2. The method for manufacturing an abrasive according to Claim 1, wherein the step of bagging the coal ash is carried out with the coal ash in a wet state.

3. The method for manufacturing an abrasive according to Claim 2, wherein in the step of classifying the coal ash, by using a wet classifier, oversize material coarser than a predetermined first particle size and undersize material finer than a second particle size smaller than the first particle size are removed.

4. The method for manufacturing an abrasive according to Claim 2, wherein in the step of classifying the coal ash, by using a wet classifier, oversize material coarser than a predetermined first particle size is removed.

5. The method for manufacturing an abrasive according to any one of Claims 1 to 4, wherein the coal ash is clinker ash.

6. The method for manufacturing an abrasive according to any one of Claims 1 to 4, wherein the coal ash is IGCC slag.

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