JPS5935675B2 - Sludge separation and collection method using water film eddy current coating booth - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sludge separation and collection method for a water film eddy current coating booth (a type of coating booth in which water circulation and exhaust cleaning are performed by an exhaust fan and no pump is used). .

Conventionally, when treating overspray mist from a water film eddy current painting booth, a water treatment agent containing an alkali metal was added to the circulating water and removed by precipitation in a water tank.

However, the settled sludge was sticky and required considerable effort to remove.

In addition, when water-based paints, which are now widely used as non-polluting and resource-saving paints, are used, the resin for water-based paints becomes an alkali metal carboxylate and dissolves, resulting in increased viscosity and foaming. However, due to problems such as the accumulation of sludge in the exhaust cleaning section, there was a drawback that circulating water could not be used effectively.

In view of the above-mentioned current situation, the present invention has been made as a result of various studies on overspray mist treatment that does not have the above-mentioned drawbacks. The overspray mist is separated from the circulating water as sludge by adding an oxide and/or a flocculating agent mainly composed of oxides, and then the separated sludge is transferred to a baffle plate or sludge suction installed in the headrace or booth water tank. This is a method for separating and collecting sludge in a water film vortex coating booth, which is characterized by collecting the sludge through a spout.

The water treatment agent used in the present invention is one in which sludge coagulates and floats when added to circulating water, that is, a flocculating floatant, which contains hydroxides and/or hydroxides of Group Ia elements of the periodic table. Oxide is an essential component, and aluminum sulfate, polychloride, etc. are added to improve the sludge's stickiness, water content, cohesiveness, flotation, filtration, adhesion to equipment, foaming of circulating water, etc. Aluminum, calcium chloride, coagulants such as ferrous sulfate, nonionic surfactants, adsorbents such as diatomaceous earth, activated clay, activated carbon, flocculants such as organic polymer compounds, antifoaming agents such as silicone. In addition, high boiling point alcohols, mineral oil, etc. are added as necessary.

Then, 0.01% or more of P is dissolved in the circulating water as a hydroxide and/or oxide of Group 11a elements of the periodic table.
When a spray operation is performed with H maintained at 9 or more, the overspray mist reacts with the water treatment agent, condenses, and floats up as sludge containing air bubbles.

The floated sludge has little adhesion and stickiness, and has an extremely low water content, so the sludge can be easily dehydrated using a simple device, and the sludge can be easily removed automatically.

The headrace is a waterway that returns circulating water discharged from the exhaust cleaning section to the booth water tank, and is provided at the rear and side portions of the exhaust cleaning section.

A baffle plate is attached to a water conduit or a booth water tank in order to collect sludge that has coagulated and floated on the circulating water surface of the water channel or the water surface of the booth water tank.

Note that a trumpet-shaped sludge suction port may be installed instead of the baffle plate.

In the present invention, by using a flocculant instead of a conventional precipitating agent as a water treatment agent, overspray mist is separated from circulating water as sludge, and the separated sludge can be used in a water conduit or Since the sludge is collected by the baffle plate or sludge suction port provided in the booth tank, there is little sludge adhering to the tank wall, and the circulating water is always clean.

By providing a water conduit, the sludge in the circulating water floats to the surface while the circulating water passes through it, resulting in complete separation and the action of the coagulating floatation agent, which further reduces the stickiness of the sludge. Therefore, its moisture content decreases.

(As a result, sludge with low stickiness and water content and high concentration can be collected in one place by a baffle plate or sludge suction port, so a separation tank and a concentration tank are not required. It can be removed very easily.

By the method of the present invention, sludge floating on the water surface can be easily collected and recovered in a short time, so the collected sludge contains less foreign matter such as dust and can be recycled as a polymer compound. It is also advantageous when used.

Next, a conventional method for a water film vortex type coating booth will be explained with reference to a drawing (FIG. 1).

1 is a booth water tank, 2 is a cleaning chamber, 3 is a spiral plate, and 4 is a sawtooth plate.

Mistakes in overspray when spraying onto the object to be coated can occur because the surface of the water in the booth water tank 1 is stripped off due to the air flow produced by the exhaust fan 6 installed at the top of the cleaning chamber 2, causing the water to overspray. The mist climbs along the swirl plate 3 and hits the eliminator 5, and is included in the scattered mist.

Therefore, when the mist falls into the booth water tank 1, the overspray mist is precipitated as sludge in the water by the water treatment agent containing the alkali metal contained in the water in the booth water tank 1.

The sludge gradually accumulates in the return waterway 7.

Note that 8 is a front plate of the cleaning chamber, and 9 is a rear plate of the cleaning chamber.

The invention will now be described with reference to the illustrated embodiments (FIGS. 2 to 5).

'Ila is the rear water conduit, and the circulating water of the booth water tank 1 can be routed through this by cutting off the lower end of the rear plate of the cleaning chamber or making a hole (9a shows the cutout part of the rear plate of the cleaning chamber). It is a waterway that leads inside.

11b is a side water conduit, which is continuous with the rear water conduit 11a.

Therefore, circulating water flows from the booth water tank 1 to the rear water conduit 11.
a, it returns to the booth water tank 1 through the side water conduit 11b.

The width of this conduit can be determined as appropriate, taking into consideration the amount of circulating water, the amount of paint to be sprayed, and the like.

Either a rear baffle plate 12a is provided in the rear water conduit 11a, a side baffle plate 12b is provided in the side water conduit 11b, or an in-tank baffle plate 12c is provided in the booth water tank 1.

These baffle plates 12a. 12b and 12c are either 1
It is sufficient to provide the baffle plates only at a few locations (in FIGS. 2 and 3, these baffle plates are shown on the same drawing for convenience).

Instead of providing these baffle plates, a trumpet-shaped sludge suction port 13 can be provided at a similar position.

It is sufficient for these baffle plates 12a, 12b, 'f2c, and sludge suction port 13 to be approximately 10 cr/l below the water surface of the circulating water and approximately 5 crr/l above the water surface, and their materials are not particularly limited. .

As shown in FIG. 4, the sludge suction port 13 is configured such that circulating water (especially the upper layer containing coagulated and floating sludge) passes through the suction port trumpet-shaped portion 13a, and then passes through the suction port. The sludge is configured so that it passes through the cylindrical portion 13b, and the sludge only accumulates in the sludge suction port 13 and does not pass through the suction port cylindrical portion 13b.

Note that the water flow in the present invention is directed to the cleaning chamber rear plate cutout 9a.
Since the water passes through the water and exits to the rear water conduit 11a, the return water channel 7 becomes unnecessary.

Therefore, as shown in FIG. 2, a partition plate 14 is provided.

Next, the present invention will be explained by examples.

Example 1 In a water film eddy current coating booth (booth width 1.8 m, circulating water volume 10001) as shown in Figs. An iron baffle plate 12b was installed at a depth of 10C7rL below the water surface.

Next, add 2 kg of calcium hydroxide and 2 kg of pronone to the circulating water.
04 (oxyethylene oxypropylene block polymer nonionic surfactant manufactured by Nippon Oil & Fats Co., Ltd.) 10 kg of a flocculating floatant was dissolved and the pH was adjusted to 13.2.

When the exhaust fan 6 is operated, the degree of depressurization in the cleaning chamber 2 is 75 water columns.
It was 7rlr/L.

In this way, while operating the water film eddy current coating booth, when 10 kg of white paint made from coconut oil-modified alkyd melamine resin was sprayed with a spray gun at a rate of 100 l/min, it floated to the side water conduit 11b. The sludge was less sticky and easier to handle.

The sludge collected by the baffle plate 12b is light, and its solid content is 9% of the solid content of the sprayed white paint.
6%, and the water content after pressure dehydration was 42%.

Also, there was less dirt in the booth water tank 1 and the cleaning room 2.

Example 2 Instead of the baffle plate 12b in Example 1, a sludge suction port 13 was provided in the side water conduit 11b.

Next, the same flocculating floatant as in Example 1 was dissolved in the circulating water, and the pH was adjusted to 13.2.

Next, the sludge suction port 13 is connected to a suction pump (not shown).
and a vacuum-type sludge dewatering device (not shown), and while operating these devices and the water film eddy current coating booth,
When 10 kg of water-soluble acrylic resin-based white paint was sprayed with a spray gun at a discharge rate of 2,001 kg/min, the sludge floating in the side water conduit 11b had almost no stickiness and was easy to handle.

The sludge collected by the sludge suction port 13 was light, its solid content was 92% of the solid content of the sprayed white paint, and its water content after pressurized dehydration was 36%.

The visibility of the water in the booth water tank 1 was 20 mm or higher, indicating that the dissolution of the paint components in the water was low.

Also, there was less dirt in the booth water tank 1 and the cleaning room 2.

Example 3 A baffle plate 12b was provided in the same manner as in Example 1.

Next, in the circulating water, 2 to 9 calcium hydroxide, 20 ky of barium hydroxide, and 0 to 2 nonionic (polyoxyethylene monooleate type nonionic surfactant manufactured by NOF Corporation) I
kg, a flocculating floatation agent consisting of 200 g of silicone antifoaming agent was dissolved, and the pH was set to .

As described above, when 50 kg of water-soluble alkyd melamine white paint was sprayed in the same manner as in Example 1 while operating the water film eddy current coating booth, the sludge that floated to the side water conduit 11b had almost no stickiness. It was in an easy-to-handle condition.

The sludge collected by the baffle plate 12b is light, and its solid content is 9% of the solid content of the sprayed white paint.
2%, and the water content after pressure dehydration was 45%.

Also, there was less dirt in the booth water tank 1 and the cleaning room 2.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing a conventional water film vortex type coating booth, and Figs. 2 and 3 are explanatory diagrams showing the state of implementation of the present invention (
FIG. 2 is a side view, FIG. 3 is a plan view), and FIG. 4 is an explanatory view showing the sludge suction port (FIG. 4 is a side view, and FIG. 5 is a plan view). 1...Booth water tank, 2...Cleaning room, 3
・・・・・・Spiral plate, 4... Serrated plate, 5...
...Eliminator, 6...Exhaust fan, 7...
...Return waterway, 8...Cleaning chamber front plate, 9...
...Cleaning chamber rear plate, 9a...Cleaning chamber rear plate cutout, 10...Booth tank side plate, 11a...
... Rear headrace, 11b - ... Side headrace, 1
2a...Rear baffle plate, 12b...Side baffle plate, 12c...Aquarium baffle plate, 13...
...Sludge suction port, 13a...Suction port trumpet-shaped portion, 13b...Suction port cylindrical portion, 14...
...Partition board.

Claims (1)

[Claims] 1 In the circulating water of the water film eddy current painting booth,
The overspray mist is separated from the circulating water as sludge by adding a flocculating floatant mainly composed of hydroxides and/or oxides of Group Ia elements, and then the separated sludge is passed through a barrier installed in the water conduit or booth water tank. A method for separating and collecting sludge in a water film eddy current coating booth, characterized in that sludge is collected by a flow plate or a sludge suction port.