Pickling is a metal surface treatment used in the stainless steel industry to remove impurities from steel and obtain optimal surfaces. This process uses mixtures of nitric and hydrofluoric acid and results in large amounts of waste acid: every hour, globally, approximately 270,000 litres of acid are used in pickling. This waste acid needs to be neutralised with slaked lime: the result is an aqueous solution destined for industrial wastewater treatment plants and a sludge that requires disposal.
Alongside the environmental impact, steel pickling works suffer from high operational costs related to the disposal of waste acid: approximately €15 million annually for each steel producer. Acid regeneration, in comparison, costs in the region of €3-€4 million a year and significantly reduces consumption of resources and waste generation.
SUSTEC has developed the REGMAX system, an innovative process for the regeneration of acids used in the steel pickling process, to provide a sustainable low-cost solution to the problem of waste acid disposal. The REGMAX system increases acid regeneration rates to over 97% and reduces operational costs by up to 91%. The patented process enables impressive recovery rates for both nitric and hydrofluoric acids and is applicable to all metal and acid concentrations, giving the freedom of choosing the optimum pickling conditions for best performance. REGMAX is the most economical solution for the regeneration of mixed acids and creates a closed material loop, removing the need for consumption or disposal of acid thus reducing the environmental impact of pickling.