INTERNATIONAL CLEANER PRODUCTION INFORMATION CLEARINGHOUSE

CASE STUDY #14 1. Headline: Minimization of organic solvents in degreasing and painting 2. Background: Thorn makes light fittings from aluminum or steel sheets. Metal working, degreasing and painting are the main phases in this production process. The degreasing of the metal sections has been carried out in the past by using the volatile organic compound, trichloroethylene, which is a pollutant and is now recognized as an environmental hazard. The painting plant consisted of an automatic liquid lacquer line, with differing colors using different organic solvents. The air pollution and the accumulated remaining products were a considerable problem, both within the plant and externally. When the company planned to expand production the local authorities ordered the company to reduce its current air emissions. As a result the company intended to install equipment to capture the trichloroethylene and incinerate the solvents from the painting plant. However, an independent research organization, by carrying out a pollution prevention audit, suggested an alternative approach having environmental benefits. Company: Thorn Jarnkonst Produces lighting fixtures for indoor and outdoor use. The production amounts to 750,000 units. They employ about 650 people and the turnover is US$93.45m per year. In 1988 the company merged with Thorn EMI the main branch being in England. Suppliers: 5-zone degreasing plant- Br Michaelsen AB, Kungalv, Sweden Automatic powder plant Gema-Voltastic AG, St Gallen, Switzerland Manual powder painting plant- Eisenmann AG, Boblingen, Germany 3. Cleaner Production Principle: Good housekeeping, process modification, material substitution. 4. Description of Cleaner Production Application: The pollution prevention audit started with an analysis of the material flow in the degreasing process. It was shown that by better housekeeping, the need for trichloroethylene degreasing could be reduced by 50%, but this has now been cut to zero. The cutting of aluminum sheets required cutting fluids which were difficult to remove without the use of chlorinated solvents. A change to biodegradable cutting oils allowed an alkaline degreasing procedure in place of the previous trichloroethylene method. The degreasing is carried out in a new piece of equipment in the form of a totally enclosed 'tunnel', 30 meters long. The metal products are suspended from an overhead conveyor and then pass through five zones where they are sprayed with various liquids. The stages carried out are degreasing, water rinse, iron phosphating to aid the adherence of the paint, water rinse, a de-ionized water rinse and drying. The liquid runs off the metal items into tanks below where it is recirculated back to the spray nozzles. Electrostatic powder painting uses polymer based paints that do not have any solvent in their formulation. A long- term was that of changing to a different color of paint. This is now accomplished by changing the whole module with containers of different colors. The company has now installed a new electrostatic powder painting line having twelve automatic powder guns. The paint is positively charged relative to the metal items. Now only 5% of the colors have organic solvents and are used only for the painting of short production runs in special colors or for retouching of the automatically sprayed items where necessary. Manual spraying is carried out in a ventilated booth fitted with two electrostatic guns. 5. Economics: The alkaline degrease turned out to be US$25,200 cheaper a year than the trichloroethylene degrease and did not require the installation of recovery equipment. The powder painting techniques have led to considerably lower working costs. The following costs for solvent painting have disappeared with the use of powder painting. Cost saving US$/year Paint 206,000 Cleaning 62,000 Disposal 47,000 Pumping 33,000 Labor 112,000 TOTAL 460,000 Capital investment US$430,000 Payback 11 months 6. Advantages: Charged degreasing techniques: The environmental advantages that have been achieved are external and also within the workplace. The company more than adequately meets the demands from the authorities. Environmental Previous Present alkaline charge per trichloroethylene degrease annum degrease Air emission 11 ton trichloro- 0 ethylene Water emission 0 water purification plant Hazardous waste 5 ton trichloro- <2 ton sludge ethylene sludge The water purification plant, which is also used for other process baths, can be used for the alkaline degreasing too and results in little additional water pollution from the degrease stage. Changed painting techniques: The environmental advantages are considerable with a large reduction of the discharge of organic solvents, reduction of hazardous waste, improved work environment and a situation which enabled production to expand without conflicting with environmental demands. Environmental Previous liquid Present powder charge per lacquering painting annum (including 5% liquid lacquer) Air emission (organic solvents)65 ton 7 ton Hazardous waste: Solvents 10 m3 2 m3 Color residues47 ton 0.2 ton Powder residues < 0.5 ton 3 ton 7. Constraints: N/A 8. Contacts:Egon Conradi/Lars Blomqvist Thorn Jarnkonst AB P O Box 305 S-261 23 Landskrona Sweden Tel: +46 418 52000 Fax: +46 418 26 574 9. Keywords:Sweden, metal, degreasing, painting, good housekeeping, material substitution, process modification, trichloroethylene, solvent, cutting fluid, electrostatic spray 10. Reviewer comments: This case study was originally published in the UNEP IE document "Cleaner Production Worldwide". In the process of preparing the document the case study underwent a technical review.