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.