WO2014037955A1

WO2014037955A1 - Extraction process of reusable material from paint sludge

Info

Publication number: WO2014037955A1
Application number: PCT/IN2012/000585
Authority: WO
Inventors: Elangovan R.; Barathi TAB
Original assignee: Maham Holdings (P) Ltd
Priority date: 2012-09-05
Filing date: 2012-09-05
Publication date: 2014-03-13

Abstract

A specific process for treating and extracting reusable material from paint sludge is disclosed. The process is carried using tailor made equipment. The extraction process increases the recovery efficiency of product upto 90% or more. The reusable materials obtained from the paint sludge are used as organic filler compounds

Description

FIELD OF THE INVENTION:

The present invention relates to a method of treating paint sludge, and more particularly, it relates to a method of extracting reusable material from paint sludge, which is a residue in the process of any painting activity using special processing equipment.

BACKGROUND OF THE INVENTION:

In general, the paint and coating industry is a major source of chemical wastes. Paint sludge is mostly produced in metal fabricating industry, appliance industry and automobile industry. Paint sludge is also produced during the painting of wood products, outdoor structures like bridges and lamp posts and all types of industrial equipment. Paint sludge typically comprises uncured polymer resins, pigments, curing agents, surfactants, and other minor formulation ingredients. In addition, paint sludge typically comprises water and/or a variety of organic solvents.

Paint sludge represents an important problem both from managerial and environmental point of view owing to its huge volumes and hazardous characteristics. In recent years, a number of processes have been developed for treating paint sludge and creating useful byproducts from it.

One such process is disclosed in U.S. Pat. No. 4,303,559 for reutilization of paint sludge includes the step of heating the resulting sludge to achieve agglomeration of the particles and thermosetting of the resin. The material thus obtained is used as building or insulating components.

U.S. Pat. No. 4,432,837 discloses a process for recovering organic solvent from the paint residue. The resultant dried residue, provided it is suitably chemically inert, is potentially useful as filler in molded plastics ware.

U.S. Pat. No. 4,980,030 discloses a method for removing a portion of the water and liquid hydrocarbons from the sludge. The high solids sludge is then heated to remove the remaining water and hydrocarbons. The heating step is designed to cure the uncured polymeric paint resins.

U.S. Pat. No. 5,129,995 discloses a process and apparatus for the continuous pyrolytic decomposition of waste stream materials (e.g. paint sludge) in which the inorganic components are recovered and recycled into essentially the same source materials from which they originated. The organic components are collected in liquid or gaseous form, as pyro oil and pyro gas respectively.

U.S. Pat. No. 5,174,898 teaches a method of treating organic sludge in which the paint sludge is subjected to aerobic biodegradation with increased dry content of the resulting sludge and the latter is then subjected to anaerobic biological degradation. The sludge from the anaerobic biostage can be dried to an inert granulate and drying vapors are recycled to the aerobic biostage.

l U.S. Pat. No. 5,223,141 discloses a method for removing and recovering solvent-based paint overspray through contact with an agitated dispersion of an organic solvent in water and then allowing the dispersion to phase separate, for separation of the organic phase from the aqueous phase. The paint solids can be recovered for further use such as filler for adhesives or can be disposed of.

U.S. Pat. No. 5,254,263 discloses a method for making a sludge powder and sealant from paint sludge and also involves the method where paint sludge is used as functional filler in preparing sealant compositions. U.S. Pat. No. 5,490,907 teaches a method and apparatus for the recovery of volatiles from an organic sludge including paint sludge. The method involves distillation for recovering solvents and the resultant product is a dry granular solid which is used in building industry as raw material or as fillers. U.S. Pat. No. 5,496,404 teaches a process for treating waste paint that can be used in the manufacture of Portland cement. The waste paint is added to the process after burning the raw materials.

U.S. Pat. No. 5,543,367 teaches a process for decomposing dried paint sludge at 900°C to recover solvent and the end products are used as reinforcing fillers.

U.S. Pat. No. 5,562,590 discloses a process for treating waste material like paint sludge. The particulate material is heated to remove the solvent, leaving a dry powder which may be used as filler for various applications.

U.S. Pat. No. 5,765,293 teaches a process for treating paint sludge in which the paint powder / sludge mixture is agitated and heated to cure the paint sludge. Processing can occur either continuously or in batch mode and can be accomplished using a mixer charged with heated gases or a heated mixer.

U.S. Pat. No. 5,922,834 teaches a method for treating waste paint sludge which may be used in compositions such as pressure sensitive sealants, automotive sealants and asphalt cement coatings. U.S. Pat. No. 5,954,970 teaches a method of treating paint sludge and processing it in the form of a dried powder which may be used as a component in asphalt, concrete and sealants.

U.S. Pat. Application No. 20080216392 discloses a method of producing a combustible fuel product from paint sludge which involves drying raw paint sludge from paint booth operations.

Prior art KR20010059068 discloses a process for preparing filler to recover and reuse waste paint sludge. The process includes an agitating step to treat the sludge to completely remove free water contained in the sludge under vacuum condition simultaneously with drying the sludge to use as fillers.

However, existing methods have ongoing problems because of complexity, difficult or inefficient treatments particularly for paint sludge. 100

Accordingly, there is a need to provide a simple process for treating the paint sludge in order to extract the reusable materials in an efficient manner and employ it in rubber industries, plastic industries, etc.

105

SUMMARY OF THE INVENTION

The present invention relates to a method of treating and extracting reusable material from 110 paint sludge, which is a residue in the process of any painting activity with special equipment.

The residue of the paint sludge contains solvents mixed with the paint waste which is extracted using a specific method of this invention.

115

The method comprises the following steps in tailor made equipment:

(i) Thermal heating, distillation and recovery of solvents first by separating VOC's from the paint sludge

120

(ii) Sludge mix is treated to a particular temperature

(iii) During the process of mixing the sludge in a mixing chamber, compatible process oil is used to fluidize the mix. The mixing process in the chamber is continued for a specific time

125 period till the fluid mix is achieved

(iv) The resultant mix is pushed out and collected in a collector

At this stage, the semi-solid residue is obtained as the final product. This semi-solid residue 130 can be used as organic reinforcing filler that can be used as a filler compound in any organic compound mix applications. Moreover, the solvent extracted can also be used for different application as alternate solvent. The solvent can be provided for different thinner application, such as washing of tools and use as partial mixer in paint or a feed for secondary treatment processes, such as up-grading processes of thinner

135

Other features and advantages of various aspects of the invention will become apparent with reference to the following detailed description.

140 BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth in the appended claims. However, the preferred embodiments of the invention, together with its further objects and attendant advantages, will be best understood by reference to the following description taken in 145 conjunction with the accompanying drawings in which:

FIG. 1 is a process flow diagram for paint waste recovery and reuse converting machine. FIG. 2 illustrates the unit details of the process equipment used for treating the paint sludge. FIG. 3 depicts graphical illustration of recovery process for raw paint sludge from spray paint 150 booth operations.

FIG. 4 depicts the graphical representation of recovery process for paint and paint gun cleaning liquid.

155

DETAILED DESCRIPTION OF THE INVENTION:

Raw paint sludge is collected as a residue from the process of any painting activity. For example, the residue may contain solvents mixed with paint waste. The method of the 160 present invention details out the treatment of residue from paint sludge such that it can be used to extract reusable materials which can be further used as reinforcing fillers in rubber compounding, plastic compounding or any other epoxy compounding.

165

Treatment process for paint sludge

The process of the present invention uses a specific kind of equipment tailored for extracting the reusable material from paint sludge. Figure 1 is a process flow diagram for paint waste 170 recovery and reuse converting machine that illustrates the extraction process of reusable materials. The paint sludge residue may contain solvents mixed with paint waste. The process equipment has a control over thermal heating, distillation and recovering solvents first by separating volatile organic compounds (VOCs) from the paint sludge.

175 Further, the sludge mix is treated to a particular temperature. During the process of mixing the sludge in a mixing chamber, the processing oil compatible with the properties is added to fluidize the mix. The mixing process in the chamber is continued for a specific time period till the fluid mix is achieved. The resultant mix is pushed out and collected,

180 Distillable solvents include paint and thinners, enamel reducers, alcohols, acetone, ketones, toluene, hexane, xylene, methanol, freon, and chlorinated solvents and most other solvents with a boiling point of up to 300-375°F. The composition of the reclaimed solvent is dependent on the mixture of waste liquids used as input into the systems. Solvent wastes should be kept, separated by their common constituents to yield the best recovery efficiency

185 because batch distillation systems cannot readily fractionate a mixture of waste fluids.

Distillation of a blend of solvents might produce a product which may not be reusable in the original application. Recovered solvent can be used as gun wash or as a low-grade cleaning solvent, significantly reducing the amount spent on these raw materials. All compounds with a boiling point lower than the target solvent will evaporate and contaminate the distilled 190 product whereas residue will remain in the still bottom. The residue is used as filler of rubber compounds.

The recovery efficiencies are 80-90%, but higher efficiencies are possible. Semi-solid residue is obtained as the final product and only the remaining waste products in the still 195 bottom used as filter or require be manifesting and sending to a licensed hazardous waste facility. This type of fillers can be applied in rubber compounding, plastic compounding or any other epoxy compounding.

The reduction in waste products due to the distillation process reduces the cost of dealing 200 with these waste solvents either through removal or through off-site solvent recovery.

Treatment unit:

205

The units of the present invention operate on the principal of heating the waste fluids to the solvent boiling point and condensing the distilled clean vapor for reuse. The batch units consist of a boiling chamber, air cooling condenser, water cooling condenser and reclaimed solvent collection container as depicted in Fig. 2. These systems are easy to use and 210 typically require the user simply to load the spent solvent into the boiling chamber and program the temperature set point and cycle time. The clean solvent emerges as the unit reaches temperature after approximately 1/2 to 1 hour and the batch will complete processing after about 10 to 12 hours.

215 Experiments with the treatment process under variable temperature are carried out and results are shown in Table 1 and 2. The graphical representations of the same are shown in Fig. 3 and Fig. 4.

220

Treatment process for raw paint sludge from spray paint booth operations

Experiment: variable temperature - 100, 125, 150, 175°C

The optimal temperature of treatment system was determined by changing the process 225 temperatures from 100 to 175°C and results shows in Figure 3 and Table 1. Optimum operating temperature was observed at 175°C for raw paint sludge from spray paint booth operations. It was observed 7.5 hrs operated and minimum power consumed at 0.94 Recovery power consumption, KWV Lit solvent.

230

Table 1: Recovery process of raw paint sludge from spray paint booth operations

Experiment: variable temperature -100, 125, 150, 175°C

The optimal temperature of treatment system was determined by changing the process temperatures from 100 to 175°C and results shows in Figure 4 and Table 2. Optimum 240 operating temperature was observed at 175°C for Paint and Paint Gun Cleaning Liquid. It was observed 12 hrs operated and minimum power consumed at 0.38 Recovery power consumption, KW/ Lit solvent. If the temperature is increased, the solvent color will be changed to brown.

245

Table 2: Recovery process of paint and paint gun cleaning liquid

250

End product characterization

The result from the treatment of paint sludge processed according to the tailor made 255 machine end waste, shown in Table 3. Samples were characterized physically and their proximate analyses were done in the laboratory. The average values of various parameters were Loss on Drying at 105°C = 12.6 percent, Loss on Ignition at 550°C =80.9 percent, calorific value = 6224cal/g.

260

Table 3: characterization of end solid products analysis results output Std. for secure

S.No Parameter unit Method sarr le landfill disposal

1 Paint filter liquid test — SW 846 9095A Pass Pass

2 bulk density gm/cc ASTM D 5057-90 0.67 -

3 pH at 30.40C - ■ SW -846 9045C 4.59 4 to 12

4 Flash Point °C SW 846 1020A >60 60°C

Loss on Drying at

5 105°C % APHA 2450 12.6

<= 20% Non

Loss on Ignition at bridgeable <= 5%:

6 550°C % APHA 2451 80.9 Biodegradable

7 calorific Value Cal/gm IS:1350-1970 6224 <2500

8 Extractable Organics % SW 846 3540 C 2.59 <4.0

9 Water soluble organic % APHA 2540 E 0.3 <20%w/W

Water soluble

10 inorganic % APHA 2540 E 0.42 <10%

11 Reactive Cyanide mg/kg SW 846 90 4 <1 250

12 Reactive sulfide mg/kg SW 846 9034 <10 500

13 total phenols (WLT) mg/L APHA 5530 B&D <1 <100

14 Ammonia as N (WLT) mg/L APHA 4500NH3 B,C 18.1 <1000

15 cyanide (WLT) mg/L APHA 4500CN-C.E <0.1 <2.0

16 fluoride as F-(WLT) mg/L APHA 4500 F-D <1 <50.0

Nitrate Nitrogen as N

17 (WLT) mg/L IS:3025 1998 4.8 <30

18 Arsenic (total) mg/kg APHA-3500 As B <10 ~

19 Arsenic (TCLP) mg/L APHA-3500 As B <0.1 <5

20 Arsenic (WLT) mg/L APHA-3500 As B <0.2 <0.1

21 Cadmium (Total) mg/kg SW 846 3050B 10686.8 -

SW 846 1311 , APHA

22 Cadmium (TCLP) mg/L 311 B 1.23 <1.0

SW 846 1311 , APHA

23 Cadmium (WLT) mg/L 311 B 1.1 <0.2

24 Total chromium (total) mg/kg SW 846 3050B, 7196A 6.88 —

SW 846 1311 , APHA

25 Total chromium (TCLP) mg/L 311 B <0.2 5

Hexavalent chromium

26 (Total) mg/kg SW 846 3060 A, 7196 A <5

Hexavalent chromium SW 846 1311 , APHA

27 (TCLP) mg/l 3500Cr B <0.2 <0.5

28 Copper (Total) mg/kg SW 846 3050B, 7210 <5 —

SW 846 1311 ,

29 Copper (WLT) mg/l APHA3 11 B <0.5 <10

30 Lead (Total) mg/kg SW 846 3050B, 7420 83.5 —

SW 846 1311 ,

31 Lead (TCLP) mg/l APHA3111 B 0.39 <5.0

While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention as claimed

Claims

CLAIMS:

A method of treating and extracting reusable materials from the paint sludge using a tailor made equipment comprising (a) extracting the solvent present in the residue of said paint sludge (b) treating the sludge mix of the paint sludge with compatible oil in a mixing chamber to fluidize the mix under suitable operating temperature and (c) reusing the semi-solid residue of resultant mix as reinforcing fillers.

The method according to claim 1 , wherein the said paint sludge residue contains solvent with paint waste and the solvent is extracted based on distillation process.

The method according to claim 1 , wherein the said extracted solvent can be used as gun wash or as a low-grade cleaning solvent.

The method according to claim 1 , wherein the said semi-solid residues are the remaining waste products in the still bottom of the mixing chamber after evaporating the solvents in the paint sludge.

The method according to claim 4, wherein the said semi-solid residues can be used as fillers in rubber compounding, plastic compounding or any other epoxy compounding.

The method according to claim 1 , minimizes the power consumption and duration of the process while optimizing the operating temperature of the system.