HK1173700B - Sand-blasting material and sand-blasting method - Google Patents

Description

Sand blasting material and sand blasting method

Technical Field

The present invention relates to a blasting material and a blasting method used for preparing a base for blasting when removing a coating or the like and spraying a metal product for the purpose of preventing rust and corrosion.

Background

In a blasting method in which a coating film is peeled off by blasting a grinding material such as sand with compressed air or the like, a dry blasting treatment is generally performed using a grinding material in a dry state. In the dry blasting, the grinding material collides with the object to be treated and is crushed, thereby generating dust, or dust such as a coating film peeled off from the surface of the object to be treated, rust of an oxide as a base material, and the like. In particular, in the case of recoating of deteriorated coating of bridges and the like in urban areas and rivers, a large cost is required for dust disposal.

Therefore, various studies have been made to prevent generation and scattering of dust generated during the operation in the dry blasting. For example, patent document 1 describes a blasting apparatus in which dust is scattered over a wide range in dry blasting and it is difficult to perform blasting work in an open space, and thus a function of spraying water or the like is added to a nozzle portion of a grinding material as needed to perform wet blasting.

Non-patent document 1 describes wet blasting in which a grinding material filled in a tank is compressed by water pressure, and the compressed grinding material is extruded in a bean jelly type with only water between particles, and is carried in blasting air. In this method, the water film is released in a parachute-like manner at the moment when the wet particles collide with the workpiece, thereby suppressing the generation of dust.

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent No. 2880498 publication

[ non-patent document ]

[ non-patent document 1] "wet pellet ブラスト", "online", SNM アジア, Inc. [ JUNDATION 22, 11, 22-DAY search ], インタ - ネツト < URL: http:// snmasia. jp/blaster 01.html >

Disclosure of Invention

As described in patent document 1, in the case of a method of spraying a dried grinding material and suppressing dust from the periphery thereof by a water spray film, since scattering of the grinding material or the like is prevented to collect the dust by water, it is necessary to increase the amount of water spray in order to reduce the generation of dust. In addition, since a large amount of wastewater is generated, there arises a problem of water treatment after treatment.

The blasting device of patent document 1 includes a tank for storing a dry-type abrasive, a main body portion on which a cut-out portion of the abrasive is mounted, a tank for storing water for spraying mist, a water pump portion for pressurizing and delivering water, hoses, and a nozzle portion for spraying, and the entire device is large in scale. In this example, a method of mixing water into the blast nozzle portion is adopted, but there is also a device having a portion for mixing water during the mixing and conveyance of the grinding material and air. However, the amount of air is absolutely large relative to the volume of water or grinding material, and in practice, not only water droplets and grinding material are mixed into the air randomly, but also particles of the grinding material are not wetted sufficiently per particle. Further, when the blasting apparatus of patent document 1 is used, it is difficult to install the entire large-scale apparatus on a scaffold for construction or the like in the case of performing on-site construction or the like, and therefore the apparatus is installed and used in the lower portion (ground or the like) of the scaffold in the vicinity of the object to be processed. Therefore, the length of the hose connecting the nozzle for performing injection and the tank becomes long, and the air compressor, which is a necessary supply source of compressed air, becomes a large-sized device with a lower processing capacity and higher strength.

In the wet blasting described in non-patent document 1, the grinding material is wetted only by hydraulic extrusion, and therefore the moisture content cannot be controlled, and the moisture content is not uniform, so that the abrasive material tends to be sprayed with excessive moisture. In particular, when a new blast is started, there is a problem that the work cannot be started until the water is distributed among the particles of the grinding material from the start of the application of the water pressure by filling the dry grinding material into the tank.

Accordingly, an object of the present invention is to provide a blasting material and a blasting method which are less likely to generate dust for removing a coating film and a grinding material during blasting, which do not require a large-scale blasting apparatus, and which do not require water treatment after blasting.

The blasting material of the present invention contains 5 to 30 mass% of water with respect to the grinding material, and is prepared in advance so that all the grinding material particles are uniformly wetted. The blasting material of the present invention is charged into a blasting material storage tank of a blasting apparatus and is sprayed with compressed air as in the case of dry blasting, whereby dust can be captured by moisture held by the blasting material and the generation of dust can be prevented. Further, according to the blasting material of the present invention, since only moisture is contained in an amount necessary for preventing scattering of dust, excessive waste water is not generated during and after the blasting treatment. Further, since the blasting material of the present invention can be supplied in a state where the moisture preparation is completed by a fine bag or the like, a conventional tank for storing water is not required.

When the content of moisture is less than 5 mass% based on the grinding material, the moisture is insufficient, and the generation of dust cannot be sufficiently prevented. On the other hand, when the content of moisture exceeds 30 mass% with respect to the grinding material, the moisture is separated from the grinding material, and an excessive amount of waste water is generated during and after the blasting treatment.

Further, the blasting material of the present invention preferably contains a surfactant. Since the blasting material of the present invention contains moisture, the blasting material is likely to agglomerate when being sent from the blasting material storage tank, and the fluidity may deteriorate. Therefore, by adding a surfactant to the blasting material of the present invention, the blasting material can be stably delivered with improved fluidity.

Further, the blasting material of the present invention preferably contains a humectant. In the purpose of the removal coating, it is effective that the abrasive has small particles (particle diameter of 0.1 to 0.15mm), and in this case, the amount of moisture that the abrasive can hold is increased (about 20 mass% at the maximum), but in the removal coating, the amount of moisture is preferably 15 to 30 mass%, and therefore, it is preferable to contain a humectant. In the spray-coated base preparation, the particles are preferably relatively large (particle diameter of 0.6 to 0.85mm), and the amount of water that the abrasive can hold is reduced (about 15 mass% at maximum), but in the spray-coated base preparation, the amount of water is preferably 5 to 20 mass%, and therefore, a humectant is preferably contained. By including the humectant in the blasting material of the present invention, the amount of moisture that can be retained by the grinding material can be increased, and moisture can be retained uniformly in the grinding material.

Further, the blasting material of the present invention preferably contains a rust inhibitor. The blasting material of the present invention contains the rust preventive agent, and thus the interval between the blasting and the coating after the blasting can be extended.

(1) The abrasive material contains 5 to 30 mass% of water with respect to the abrasive material and is prepared in advance so that all abrasive material particles are uniformly wetted, and the object to be treated is sprayed in the same manner as in dry blasting, whereby the moisture held by the abrasive material can be used to collect dust, and the generation of dust can be prevented. Further, since excessive waste water is not generated during and after the blasting treatment, water treatment other than treatment of the grinding material after the treatment is not required. Further, the entire blasting apparatus can be provided on a scaffold used for on-site construction or the like because the entire blasting apparatus can be downsized by providing the blasting apparatus by dividing the bag or the like without using a conventional tank for storing water. Further, since the hose connecting the nozzle for performing the injection and the blasting material storage tank has the shortest length, the reduction of the processing capacity can be reduced, and a small-sized air compressor can be used.

(2) By containing the surfactant, fluidity is improved, and the blasting material can be stably delivered from the blasting material storage tank.

(3) By containing the humectant, the amount of moisture that can be retained by the grinding material can be increased, and moisture can be retained uniformly in the grinding material.

(4) By containing the rust preventive, the interval between the thermal spraying and the painting after the blast treatment can be extended. For example, in the case of a base preparation blasting treatment for thermal spraying, as described in JISH8300, there is a limit that the treatment should be carried out within 4 hours from the blasting treatment to the thermal spraying, but by containing a rust inhibitor, the decrease in adhesion of the thermal spray coating at the time of thermal spraying after 1 to 2 days can be suppressed, and the workability can be improved.

Drawings

Fig. 1 is a schematic configuration diagram of a blasting apparatus using a blasting material according to an embodiment of the present invention.

Fig. 2 is an explanatory diagram comparing a blasting apparatus according to an embodiment of the present invention with a conventional blasting apparatus.

Fig. 3 is an explanatory view showing conditions of the blast test.

Fig. 4 is a schematic diagram showing various states of the steel plate 7 in the example of the present invention.

Detailed Description

Fig. 1 is a schematic configuration diagram of a blasting apparatus using a blasting material according to an embodiment of the present invention. In fig. 1, a blasting apparatus as a blasting apparatus according to an embodiment of the present invention includes a blasting material storage tank 2 that stores a blasting material 1 as a blasting material, a blasting nozzle 3 that performs blasting of the blasting material 1 on an object X to be treated, and a blasting hose 4 that connects the blasting material storage tank 2 and the blasting nozzle 3. Furthermore, the blasting device is additionally connected to an air compressor 5 which supplies compressed air.

A cut-out portion 2a for cutting out the blasting material 1 and a mixing portion 2b for mixing the blasting material 1 with compressed air and feeding the mixture into the blasting hose 4 are provided at a lower portion of the blasting material storage tank 2. The mixing section 2b is connected to the air compressor 5 through an air hose 6 a. Further, the air compressor 5 is connected to the upper portion of the blasting material storage tank 2 through an air hose 6 b.

The blasting material storage tank 2 in the embodiment of the present invention is a pressurized type that feeds the blasting material 1 by pressurizing with compressed air, but may be an open type without pressurization. In addition, since the blasting material 1 in the present embodiment often has a lower fluidity than a conventional dry grinding material, the cutting portion 2a is constituted by various quantitative cutting devices such as a disk feeder, a screw feeder, or a rotary valve feeder, and is quantitatively cut and supplied to the mixing portion 2 b.

The air compressor 5 may be of an electric type or an engine type. Oil, moisture, and the like in the compressed air generated by the air compressor 5 are supplied to the blasting material storage tank 2 and the mixing section 2b through the air hoses 6a and 6b by a liquid discharge removal device, not shown. Although not shown, an operation switch, valves, and the like are provided for starting and stopping the blasting device.

The blasting material 1 used in the blasting apparatus is prepared to have a moisture content of 5 to 30 mass% with respect to the grinding material, and to have a uniform wetting of all the grinding material particles. As the grinding material, all kinds of non-metallic grinding materials for blasting, for example, alumina, garnet, silica sand, glass beads, silicon carbide, slag (slag), and the like can be used. The grinding material and water are mixed and prepared in advance, and for example, the grinding material and water are packed in a fine bag or the like in 1 bag of 10 to 25 kg. Besides water, commercially available rust inhibitors, surfactants, humectants, and the like may be contained.

Examples of the rust inhibitor include commercially available amine rust inhibitors. Examples of the surfactant include commercially available naphthalenesulfonic acid formalin compounds, sodium alkylbenzenesulfonates, polyoxyethylene alkyl ethers, and polyoxyethylene fatty acid methyl esters. As the humectant, commercially available sodium polyacrylates and the like can be used, for example.

The water content is adjusted within the range of 5 to 30 mass% depending on the kind, particle size, etc. of the grinding material. For example, when the grinding material is alumina and the particle size is 0.1 to 0.15mm, bags filled with grinding materials of different types having different moisture contents to some extent, such as bags having a moisture content of 5 mass%, bags having a moisture content of 10 mass%, bags having a moisture content of 30 mass%, and the like, are prepared. Further, the bag filled with the blasting material 1 uses a protection bag which does not change the moisture amount due to evaporation or the like.

When the surfactant is contained, the surfactant is contained in an amount of, for example, 0.1 to 5 mass% with respect to the water content contained in the blasting material 1. In the case of a grinding material having an alumina particle diameter of 0.1 to 0.15mm, when the blasting material is discharged from the blasting material storage tank 2 to the cut-out portion 2a and discharged from the cut-out portion 2a to the mixing portion 2b, the blasting material 1 is likely to be agglomerated and the fluidity may be deteriorated, and therefore, the fluidity is improved by the inclusion of the surfactant. Thereby, the blasting material 1 can be stably fed from the blasting material storage tank 2.

The blasting material 1 preferably contains a humectant. When the particle diameter of the grinding material is 0.1 to 0.15mm, the amount of moisture that can be retained by the grinding material is about 20 mass%, and when the particle diameter is 0.6 to 0.85mm, the amount is about 15 mass%, so that moisture exceeding the amount cannot be retained in the grinding material and separated. Therefore, if the humectant is contained, the amount of moisture that can be retained by the grinding material can be increased, and the moisture can be uniformly retained in the grinding material.

In addition, when the grinding material contains a rust inhibitor, a surfactant, a humectant, and the like in addition to water, the total amount of the rust inhibitor, the surfactant, the humectant, and the like and water is preferably 5 to 30% by mass based on the grinding material. Thus, even when a rust inhibitor, a surfactant, a humectant, or the like is contained, the ratio of the grinding material in the entire blasting material is not changed, and thus the target blasting performance can be maintained.

In the blasting apparatus having the above-described configuration, only a necessary amount of the blasting material 1 prepared in advance is charged into the blasting material storage tank 2. When the blasting apparatus is started, compressed air from the air compressor 5 is supplied to the blasting material storage tank 2 and the mixing portion 2b, and is ejected from the blasting nozzle 3 through the blasting hose 4. The blasting material 1 is quantitatively cut by the cutting portion 2a and sent to the mixing portion 2 b. Then, the blasting material 1 is pulverized by the compressed air in the mixing portion 2b, and is carried in the jet of the compressed air, passes through the inside of the blasting hose 4, and is jetted from the jet port 3a of the blasting nozzle 3.

The blasting material 1 collides with the surface of the object X to peel off the coating film, rust, dirt component and other deposits Y, and then scatters around the object X and deposits. In the blasting material 1 of the present embodiment, since the surface of the abrasive particles is always covered with the water-containing coating film, when the abrasive particles are ejected from the blasting nozzle 3 and collide with the surface of the object X to be processed, the water contained in the abrasive particles is first ejected onto the surface of the deposit Y, and then the abrasive particles crush and peel off the deposit Y. Therefore, the dust of the adhering matter generated at the time of crushing and peeling of the adhering matter Y can be effectively wetted, and the generation of the dust can be suppressed.

In addition, since the blasting material 1 according to the embodiment of the present invention can be used by arbitrarily selecting, for example, a divided bag of different blasting materials 1 having a moisture content of 5 to 30 mass% as necessary, it is possible to suppress the generation of dust in accordance with the state of the object X to be treated. In addition, in the blasting material 1 of the present embodiment, even when the ejection amount is unstable and fluctuates, only water is not ejected, and the moisture amount is constant with respect to the ejected blasting material 1, so that scattering of excessive moisture and excessive generation of dust due to insufficient moisture can be suppressed.

As described above, according to the blasting material 1 in the embodiment of the present invention, by spraying the object X to be treated in the same manner as in the dry blasting, the moisture held by the blasting material 1 can be used to capture the dust, and the generation of the dust can be prevented. Further, since excessive waste water is not generated during and after the blasting treatment, water treatment other than the treatment of the grinding material after the treatment is not required.

A difference between the blasting apparatus according to the embodiment of the present invention and a conventional blasting apparatus will be described with reference to fig. 2. Fig. 2 is an explanatory diagram comparing a blasting apparatus (fig. 2(a)) according to an embodiment of the present invention with a conventional blasting apparatus (fig. 2 (b)).

As shown in fig. 2(a), in the blasting apparatus according to the embodiment of the present invention, a blasting material storage tank 2 is provided on a scaffold and connected to an air compressor 5 provided on the ground through an air hose 6, whereas as shown in fig. 2(b), in the conventional blasting apparatus, a blasting material storage tank 10, a water supply device 11 including a water tank 11a and a water pump 11b, and an air compressor 12 are provided on the ground, and a blasting nozzle 13 extending from the ground to the scaffold is connected to a water hose 15 through a blasting hose 14.

As shown in fig. 2, in the blasting apparatus according to the embodiment of the present invention, since the blasting material 1 containing 5 to 30 mass% of water with respect to the grinding material can be supplied by the divided bag 1a or the like and prepared so that all the grinding material particles are uniformly wetted in advance, the water tank 11a, the water pump 11b, the water hose 15, and the like of the conventional blasting apparatus are not required, the entire blasting apparatus can be downsized, and the entire blasting apparatus can be installed on a scaffold used in site construction or the like.

Therefore, the blasting nozzle 3 for performing blasting and the blasting hose 4 for connecting the blasting material storage tank 2 are made the shortest length, so that the reduction of the processing capacity can be reduced, and the small-sized air compressor 5 can be used. On the other hand, in the conventional blasting apparatus, since moisture is supplied by the water tank 11a and the water pump 11b, the apparatus is large, and therefore, the apparatus cannot be installed on a scaffold, and the water needs to be supplied from the ground to the scaffold through the long water hose 15, which inevitably increases the length of the blasting hose 4.

Examples

The blasting test was performed by using the blasting apparatus of the blasting material 1 in the above embodiment. As shown in FIG. 3(a), the test was carried out using a square steel plate 7 having a side length of 1 m. The steel plate 7 was a black skin steel plate (SS400) having a thickness of 3.2 mm. The steel plate 7 was vertically mounted on a support base (not shown) as shown in fig. 3 b, and the blasting material 1 was ejected from the tip of the blasting nozzle 3 through the blasting hose 4 onto the steel plate 7 in a state where the blasting nozzle 3 was fixed so as to face the center of the steel plate 7 with a right angle of ejection angle and a distance between the steel plate 7 and the tip of the blasting nozzle 3 of 200 mm.

This state is a state where the blasting material 1 collides with the surface of the steel sheet 7 to remove the oxide coating (black skin) on the surface of the steel sheet 7, and in normal dry blasting, dust is generated. At this time, the generation state of dust and the diffusion mode of moisture adhering to the surface when the various blasting materials 1 were projected were observed, and the effect of the blasting materials 1 was confirmed. The amount of the blasting material 1 was set to various amounts of water with respect to 1kg of the grinding material. Sodium alkylbenzenesulfonate as a surfactant and sodium polyacrylate as a humectant are added as appropriate in accordance with the moisture content.

The sandblasting material 1 (grinding material 1kg + moisture) was projected for about 1 minute, and the state of the surface of the steel plate 7 was observed and evaluated. The evaluation criteria were performed based on the evaluation criteria table shown in table 1. The test results are shown in tables 2 to 6.

[ Table 1]

[ Table 2]

[ Table 3]

[ Table 4]

[ Table 5]

[ Table 6]

From the results, it is understood that when the moisture content is less than 5 mass%, the generation of dust is large, and the dust suppression effect by the moisture is small. In addition, when the moisture content exceeds 30%, generation of dust is reduced, but after the blasting treatment, moisture is separated from the grinding material and excessive moisture droops, so that an excessive water treatment is necessary in addition to the treatment of the grinding material. From this, it was confirmed that when the blast material 1 containing 5 to 30% of water with respect to the grinding material and prepared in advance so that all the grinding material particles were uniformly wetted was used, generation of dust was suppressed and excessive water treatment after the treatment was not necessary.

In order to confirm the effect of the rust inhibitor, a sprayed coating was produced by the blasting method of the present example and the conventional dry blasting method, and the adhesion of the sprayed coating was measured to confirm the effect of the rust inhibitor. A steel sheet of SS400 as a test piece was subjected to blasting with a grinding material of the same grain size, and in the blasting method of this example, a sprayed coating was formed 2 days after the blasting. In the conventional dry blasting method, a spray coating is formed 2 hours after blasting (within 4 hours in JISH 8300). The adhesion of the coating film was measured by the method "a.2.2 tensile adhesion strength test (method a)" described in annex a of JISH8300 (2005) (method a さ test test (method a)) as a measure of a 2.2 primer adhesion strength. The test conditions and test results are shown in table 7.

[ Table 7]

From the results, it was found that when the blasting material 1 of the present example was used in the base preparation blasting for thermal spraying, it was confirmed that the adhesion of the thermal spray coating was not lowered when the thermal spraying was performed after 2 days, regardless of the restriction that the blasting had to be performed within 4 hours from the blasting until the thermal spraying.

Industrial applicability

The blasting material and the blasting method of the present invention are useful for blasting treatment for preventing generation and scattering of dust generated in a base preparation operation during removal of a coating deteriorated for rust prevention and corrosion prevention of a metal product and thermal spraying. In particular, in the case of recoating of deteriorated coating such as a bridge in an urban area or a river, a large cost is required for handling dust, and in contrast, the present invention can greatly reduce the generation of dust itself, and is therefore suitable for greatly reducing the cost of recoating or spray coating work.

Description of the reference numerals

1 sandblasting Material

2 Sand blasting material holding vessel

3 Sand blasting nozzle

4 Sand blasting hose

5 air compressor

6. 6a, 6b air hoses.

Claims (4)

1. A blasting material containing 5 to 30 mass% of water with respect to a grinding material, prepared in advance to be uniformly wetted with respect to all the grinding material particles, wherein the blasting material contains a surfactant, and the blasting material contains 0.1 to 5 mass% of the surfactant with respect to the water contained in the blasting material.

2. The blasting material of claim 1, wherein the blasting material comprises a humectant.

3. The blasting material according to claim 1 or 2, wherein the blasting material contains a rust inhibitor.

4. A blasting method, wherein a blasting material containing 5 to 30 mass% of water with respect to a grinding material and prepared in advance to be uniformly wetted with all the grinding material particles is charged into a blasting material storage tank of a blasting device and is blasted onto an object to be treated by compressed air, wherein the blasting material contains a surfactant, and the blasting material contains 0.1 to 5 mass% of the surfactant with respect to the water contained in the blasting material.