Apparatus and method for recycling waste paint

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to waste paint generated during a painting operation and more particularly to apparatus and method for recycling waste paint to dry up the waste paint containing an amount of toxic substances in a vacuum dry method and completely remove water from the waste paint.

2. Description of Related Art

Typically, paint contains pigment, organic matter, inorganic matter, a drier, an additive, and resin. The paint has various physical properties in accordance with usage and contains an amount of water and thinner, thus having its unique smell. If waste paint generated during a painting operation is discharged as it is, it may cause environmental pollution such as air pollution, soil pollution, marine pollution, and water pollution, so it is defined as a particular toxic substance.

In a conventional treatment method, the waste paint is collected and burned up. However, this incineration of the waste paint costs a great deal and generates an amount of volatile organic compounds (VOC), causing secondary pollution.

To overcome the above problems, there have been developed methods and apparatus for recycling the waste paint. The method and apparatus for recycling the waste paint is disclosed in the application Ser. No. 96-6501 filed in Korea (the title of the invention is “Method and Apparatus for recycling waste paint”) in detail. Specifically, in a course of drying up the waste paint, electromagnetic wave generated by a magnetron is used as a primary energy source and hot air generated by a hot blast stove is used as a secondary energy source to remove water from the waste paint.

However, the above method and apparatus for recycling waste paint using the electromagnetic wave does not allow mass production and good drying. Moreover, a terrible smell that is given off by drying of the waste paint and fillers generated from the recycling process not only ruins worker's health but also causes environmental pollution. The fillers cannot be reused because the conventional recycling method of waste paint cannot remove a terrible stink from the fillers.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to apparatus and method for recycling waste paint that substantially obviates one or more of the limitations and disadvantages of the related art.

An objective of the present invention is to provide apparatus and method for recycling waste paint, which removes a bad smell generated in the course of drying up the waste paint.

Another objective of the present invention is to provide apparatus and method for recycling waste paint, which dries up the waste paint using a vacuum dry method, thereby reducing secondary pollution and allowing mass production.

Still another objective of the present invention is to provide apparatus and method for recycling waste paint, which removes a bad smell from fillers, thereby allowing reuse of the fillers.

Additional features and advantages of the invention will be set forth in the following description, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure as illustrated in the written description and claims hereof, as well as the appended drawings.

To achieve these and other advantages, and in accordance with the purpose of the present invention as embodied and broadly described, a method for recycling waste paint comprises the steps of: shaping the waste paint into a cake of a predetermine thickness while removing water from the waste paint using centrifugal force of a dehydrator; drying up and dehydrating the cake-shaped waste paint at about 80° C.˜300° C. using a twin screw extruding method to remove water; drying up the waste paint dried up at the above step at about 100° C.˜300° C. using a vacuum dry method to remove remaining water; pulverizing the waste paint dried up by the vacuum dry method into minute powder; separating the pulverized waste paint based upon density; and collecting and discharging dust, vapor, and gas generated during the above steps.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

In the drawings:

FIG. 1

is a block diagram for showing processes of a method for recycling waste paint according to a preferred embodiment of the present invention; and

FIG. 2

is a schematic diagram showing a configuration of a drying furnace of a waste paint recycling apparatus according to a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

The preferred embodiments of the present invention will now be described in detail referring to the accompanying drawings. It will be noted that the same elements in different drawings are designated by the same reference numerals. In describing the present invention, specific description of related known functions or structure that may confuse the essential subject of the present invention will be omitted.

FIG. 1

is a block diagram for showing processes of a method for recycling waste paint according to a preferred embodiment of the present invention. Referring to

FIG. 1

, the configuration of a waste paint recycling apparatus will be described.

A reference numeral

100

indicates a rotating dehydrator for shaping waste paint into a cake having a proper thickness using centrifugal force of a screw. A reference numeral

110

indicates a first drying furnace having a single or twin screw extending machine, for drying up the waste paint. A reference numeral

120

is a second drying furnace for drying up the waste paint dried up by the first drying furnace

110

once more using a vacuum drier. The configuration of the second drying furnace will be described later. A reference numeral

130

is a first pulverizer for pulverizing the waste paint dried up by the second drying furnace

120

and

140

indicates a second pulverizer for pulverizing the pulverized waste paint into minute powder. A reference numeral

150

is a separator for separating the waste paint that is pulverized into the minute powder by the second pulverizer

140

based upon density. A reference numeral

190

is a first dust collector for collecting dust, vapor, and gas generated from the first and second drying furnaces

110

and

120

, the first and second pulverizers

130

and

140

and the separator

150

. A reference numeral

180

is a second dust collector for collecting gas that is not filtered out by the first collector

190

. Reference numerals

160

and

170

indicate air deodorizing machines for deodorization of the gas.

FIG. 2

is a schematic diagram showing a configuration of the second drying furnace for completely drying up the waste paint in a waste paint recycling apparatus according to a preferred embodiment of the present invention. The second drying furnace

120

comprises a boiler

10

, a drying tank

20

, and a vacuum pump

34

. The boiler

10

is connected to the drying tank

20

via a pipe

40

a

and maintains the inside of the drying tank

20

at a predetermined temperature. The drying tank

20

, which dries up the waste paint primarily dried up by the first drying furnace

110

once more, has a blade

22

mounted to a shaft

26

therewithin. The blade

22

receives driving force from a motor

24

and rotates to dry up the waste paint. In other words, an internal heat source (provided by the boiler) of the drying tank

20

is uniformly spread by the rotation of the blade

22

, thus uniformly drying up the waste paint. A funnel-shaped hopper

12

and a filter

14

are mounted to the top of the drying tank

20

. The filter

14

filters out gas and vapor generated in the course of drying up the waste paint. An outlet

28

for discharging the completely dried-up waste paint toward the first pulverizer

130

is mounted to the bottom surface of the drying tank

20

. The filter

14

of the drying tank

20

is connected to a receiver pump

30

and the vacuum pump

34

. That is, the upper end of the receiver pump

30

is connected to one end of a duct

32

and the other end of the duct

32

is connected to the vacuum pump

34

via a pipe

40

c.

An intermediate part of the duct

32

is connected to the filter

14

of the drying tank via a pipe

40

b.

The vacuum pump

34

continuously sucks the air in the drying tank

20

via the pipe

40

c,

the duct

32

and the pipe

40

b

to make vacuous. The receiver pump

30

sucks in the vapor and gas generated when the drying is performed at the drying tank

20

. A condensing device

39

is mounted to a connecting portion of the pipe

40

b

and the duct

32

to condense the vapor and discharge the condensed water through a water outlet

38

that is mounted to the lower part of the duct

32

. The gas and the vapor not condensed is discharged through a gas outlet

36

that is mounted to the upper part of the duct

32

.

A method for recycling the waste paint by using such waste paint recycling apparatus including the drying furnace will now be described in detail with reference to

FIGS. 1 and 2

.

The waste paint recycling method comprises a dehydration step, a drying step, a dust collecting step, a pulverizing step, and a separating step. Primarily, collected waste paint is carried to the dehydrator

100

by a screw conveyor

50

. The waste paint is shaped into a cake of a proper thickness while the water is removed from the waste paint by the dehydrator

100

.

The cake-shaped waste paint is carried to the first drying furnace by a screw conveyer

52

. The first drying furnace

110

dries up portions that was not dried up at the dehydration step using a twin screw extruding method while maintaining a temperature at about 80° C.˜250° C. to reduce the water content of the waste paint to 10% or less. The water generated during the drying step is discharged through an outlet

54

and gas and vapor is delivered to the first dust collector

190

through a delivery pipe

56

. The waste paint primarily dried up by the first drying furnace is carried to the second drying furnace

120

by a belt conveyer. The waste paint is dried up once more using a vacuum dry method at the proper temperature that is maintained by the heat source under forced vacuum in the second drying furnace. In other words, as shown in

FIG. 2

, the waste paint dried up by the first drying furnace

110

is fed to the drying tank

20

via the hopper

12

. Subsequently, the boiler

10

, the receiver pump

30

, and the vacuum pump

34

are activated. The boiler

10

maintains the internal temperature of the drying tank

20

at about 100° C.˜300° C. The vacuum pump

34

continuously sucks the air in the drying tank

20

to make the drying tank

20

be in a forced vacuous state. Simultaneously, the blade

22

is rotated by the driving force of the motor

24

and the resultant rotary power allows the uniform spread of the heat source within the drying tank

20

. While the waste paint is dried up by the heat source of the boiler under the vacuous state, gas and vapor is generated. The vapor and gas passes through the filter

14

. The vapor and gas that has passed through the filter

14

is flowed into the duct

32

through the pipe

40

b.

The vapor is condensed by the condensing device

39

. The condensed vapor is discharged through the water outlet

38

by the driving force of the receiver pump

30

. The gas and the vapor not condensed are discharged through the gas outlet

36

. Here, the gas that is generated when drying up the waste paint is carbon monoxide (CO), carbon dioxide (CO

2

), hydrogen (H

2

), and formaldehyde. The vapor and gas that is discharged through the gas outlet

36

is delivered to the first dust collector

190

through a delivery pipe

58

. Through the above operations, the waste paint is completely dried up in the second drying furnace

120

. At this time, the water contained in the waste paint is less than 0.05%.

The waste paint completely dried up by the second drying furnace

120

is cooled by a cooling air and then carried to the first pulverizer

130

by the belt conveyer. The first pulverizer

130

pulverizes the dried-up waste paint into a predetermined size. Dust generated during the pulverization is flowed into the first dust collector

190

through a delivery pipe

64

. Subsequently, the primarily pulverized waste paint is pulverized into minute powder by the second pulverizer

140

and deodorized with a deodorant. Dust generated during the second pulverizing step is flowed into the first dust collector

190

through a delivery pipe

66

.

Thereafter, the waste paint pulverized into the minute powder is delivered to the separator

150

. The separator

150

separates the waste paint of the minute powder into three classes of less than 200 meshes, 200 through 300 meshes, and more than 300 meshes to manufacture three kinds of products. A blower

62

for supplying the air is installed to the separator

150

to facilitate separation. The separator

150

also separates the waste paint inappropriate for the products from the other waste paint that is pulverized by the second pulverizer

140

and feeds back the inappropriate waste paint to the second pulverizer

140

. Dust and vapor generated from the separator

150

is delivered to the first dust collector

190

through a delivery pipe

68

.

The first dust collector

190

collects and filters out the dust, vapor, and gas generated from the first and second drying furnaces

110

and

120

, the first and second pulverizers

130

and

140

and the separator

150

. Thereafter, the vapor and gas that was not filtered out by the first dust collector

190

is delivered to the second dust collector

180

through a delivery pipe. Subsequently, the second dust collector

180

filters out the gas and vapor. The filtered gas is deodorized by the air deodorizing machines

170

and

160

and then discharged outside. Minute powder collected by the first and second dust collector

190

and

180

is returned to the separator

150

through circular delivery pipes

72

and

70

.

Through such processes, the waste paint collected during the painting operation becomes a product

200

of minute powder.

As described above, the present invention dries up the waste paint just using the vacuum dry method instead of using the electromagnetic wave of the prior art, thus improving the efficiency in drying up the waste paint and realizing mass production. The present invention also removes a bad smell generated in the course of drying up the waste paint completely, thereby realizing comfortable working environment.

It will be apparent to those skilled in the art that various modifications and variations can be made in the apparatus and method for recycling waste paint of the present invention without deviating from the spirit or scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.