INTERNATIONAL CLEANER PRODUCTION INFORMATION CLEARINGHOUSE

Case Study #70    
1.   Headline: Brass, copper, and stainless steel pickling       
without using nitric and chromic acids.    
2.   Background: Industrial brass and copper articles must be       
treated to eliminate superficial layers of oxide to give       
them a permanent smart appearance.  In the traditional       
pickling technology, nitric and chromic acid are used with       
high atmospheric (NOx) and water (metal, nitrate, cromate)       
pollution hazards.  In addition to waste streams treatment       
before release, gas and liquid disposal costs are also       
high.  An alternative chemical pickling process, using       
organic peroxides (HO) was developed.  It can be set up       
without plant modification, it is easy to operate and cost       
and quality effective.   The technology is applicable to       
stainless steel coils, wire rods, tube, and  in the       
treatment of stainless steel.    
3.   Cleaner Production Principle: New technology    
4.   Description of Cleaner Production Application: This case       
study, carried out in 1992, illustrates a technology that       
makes use of organic peroxides for brass, copper and       
stainless steel pickling, lustering and surface       
passivation.  Nitric and chromic acid are then eliminated       
with a consequent reduction of atmospheric emissions of       
NOx and elimination of N03- and CrO4- ions in the waste       
water.  Besides, simplifying the liquid waste       
purification, the technology makes the water processed       
reusable and therefore closes the loop.  The electrolytic       
process can be applied to the recovery of metals contained       
in water out-streams.  It has been in operation since       
1987.    
5.   Economics: Regarding investment costs, the plant, though       
designed for the traditional technology, notes that it can       
manage the new process without modifications.  Hence,       
further investment costs were not necessary for the       
implementation of the technology.         
Operational and maintenance costs differed between the two       
approaches.  Considering the cost of the product itself,       
of treatment, and of loss of metals, the traditional       
pickling using nitric and chromic acid ran about 100       
lire/kilo and using the new technology costs ran 35       
lire/kilo.    
6.   Advantages: The main cleaner production benefits are:         
-- elimination of atmospheric pollution NOx from nitric       
acid reaction;       
-- cleaner pickling reaction, hazardous material (100       
tons/y of nitric acid and 5 tons/y are of chromic acid)       
are replaced by peroxides;       
-- sludges reduced to 1/3;       
--closed loop recycling: purified output streams can be       
recycled to the pickling bath; and       
-- resource conservation: less water, reagents, and energy       
consumption.    
7.   Constraints: No information provided.    
8.   Contacts:    
ERGON s.r.l.  
Via Battaglioni Edolo, 14  
I 20034 Giussano  
Milano Italy  
TEL: +(39.3) 628.527.43    
Mr C Fontant  
Via Volta, 7  
I - 20050 Verano Brianza  
Milano, Italy  
TEL: 39 362 907498  
FAX~ 39362 RE2743    
Mr G Bardone  
ENEA CRE Casaccia  
Dip Ambiente  
Via Anguillarese 301  00060 
- S Maria di Galeria 
ROME  Italy  
TEL: +(39.6) 3048 6662  
FAX: +(39.6) 3048 3220    
9.   Keywords: Italy, metal, metal finishing, pickling, new       
technology, acid, peroxide, electrolyse, brass, copper,       
stainless steel, iron and steel    
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.