Acid regeneration at Avesta Steelworks

The primary reason for this major investment by Outokompu is an environmental requirement that imposes a reduction in nitrate emissions to the Dalälven (the “Dal river”). It is calculated that acid recycling will reduce nitrate emissions to one third of today’s levels.

“The project is in an intensive phase. We are finishing the fabric of the building itself. Process installation comes after that,” explains Jonas Nordlöf, project manager.

Construction of Outokumpu’s acid recycling plant started in November 2009 and operation is scheduled for May 2011. However, Jonas Nordlöf reveals that, to enable testing throughout winter and spring, plant start-up will be as soon as the end of this autumn.

In the manufacture of stainless steel plates, the nitric and hydrofluoric acids used in the annealing and pickling line at Avesta Jernverk are toxic. The process itself generates environmentally hazardous waste in the form of nitrates and metal sludge.

Thanks to the new plant, it will be possible to recycle over 95 percent of the acid. Consequently, consumption of new acid will decrease dramatically. Metal ions released during the cleaning of stainless steel plates will also be separated and used again in the process. This further reduces the load on the environment.

The acid recycling plant is Outokumpu’s largest environmental investment in Avesta. It is to cost a little over SEK 300 million and is the first of its kind in Europe to use the Steuler Total Acid Regeneration (STAR) process.

For understandable reasons, the plant uses a great deal of acid-resistant plastics. Stainless steel is used primarily in process equipment and in pipes for liquefied petroleum gas, water and compressed air.

“We also have a small furnace, a roaster, made in Inconel, a special type of stainless steel. This is acid resistant and has a very high nickel content,” says Jonas Nordlöf.

He states that the German welding company, Kramer & Best, selected Avesta Welding electrodes, “Because, quite simply, they were the best choice.” Welding is being carried out from June to August this year.

Acid recycling is part of the large capacity-increasing investment decided on by Outokumpu in September 2007. Owing to the poor economic climate, most of the group’s investments were shelved in December 2008. The acid recycling plant is one of the few to have been maintained.

Jonas Nordlöf feels that the plant is a reason for optimism, both for the company and the community at large.

“This is an entirely new process for us. It is creating new employment opportunities. As the plant, which will be 25 metres high, is on the edge of our complex and quite visible, the region’s people will be able to see that things are happening.” He hopes that this may create a positive spiral locally.

As project manager, Jonas Nordlöf’s challenges include ensuring that the programme runs to time and budget. So far, everything is looking good.

“Then, so that we achieve the environmental goals, the recycling process must, of course, work as planned. The final results will only be known around a year from now,” he concludes.