INTERNATIONAL CLEANER PRODUCTION INFORMATION CLEARINGHOUSE

1.   Headline: A cryogenic process for paint removal from steel       
structures, using liquid nitrogen instead of acids or       
pyrolithic oven.    
2.   Background: February 1993   
 
3.   Cleaner Production Principle: Material substitution    
4.   Description of Cleaner Production Application: The process       
for paint removal is based on liquid nitrogen's ability to       
quicken cooling. The differing rates at which the material       
of the structure and paint coat contract results in cracks       
in the paint. By means of mechanical action the paint coat       
is then removed. The resulting solid waste can be used for       
the production of plastic objects.         
Specifically, objects to be treated are placed in a tank       
containing liquid nitrogen (-196C). Due to the different       
contraction between the steel structure and paint coat,       
the paint cracks and can be removed by mechanical action.       
The process can be realized in a continuous and completely       
automated plant. Conventional processes utilize acid       
dripping or pyrolitic ovens and produce pollutants. Liquid       
nitrogen, chemically inert, is already in the atmosphere       
and can be obtained at low cost. This type of process does       
not produce liquid waste. The solid waste that is produced       
can be recovered and utilized to produce plastic objects.       
Existing plant capacity is 2500 Kg/h of objects to be       
treated. The technology has been fully implemented and in       
operation since 1990. It is covered by a patent.    
5.   Economics: Referring to 2.500 Kg/h of treated objects the       
investment cost is $220.000 - $250.000 US. Payback time is       
1/1.5 year.    
6.   Advantages: In addition to the benefits outlined above,       
nitrogen is a comparatively low cost raw material and the       
objects processed by this technology have a life span five       
times longer compared to those produced by other       
processes.    
7.   Constraints: This process has a high productivity until       
3.000 Kg/h.    
8.   Contacts:       
Sig Attilio Bernasconi       
BETA RICERCHE       
Via Caduti, 6       
28015 Alzate di Momo (NO) ITALY       
TEL: 39-321 926520       
FAX: 39-321 925060         
Mr G Bardone       
ENEA CRE Casaccia       
Dip Ambiente       
Via Anguillarese 301       
00060 - S Maria di Galeria       
ROME Italy       
TEL: 396 3048 6662       
fax: 396 3048 3220    
9.   Keywords: Italy, paint removal, material substitution,       
cryogenic process, nitrogen, acid, pyrolithic oven    
10.  Reviewer's comments: This case study was submitted to UNEP       
IE in 1994 by Italy's ENEA. It was reviewed and edited by       
UNEP IE in July 1995. It has not undergone a formal       
technical review.