SOLUTIONS FOR STAINLESS STEEL INDUSTRY
NEED FOR STAINLESS STEEL PICKLING
During the production of stainless steel strips, plates, tubes or wires the products need to be cleaned from oxide layers formed during their fabrication. The oxides are weakening the corrosion resistance of the material. Additionally chromium is depleted in the material directly under the oxide layer. To restore corrosion resistance it is vital that the oxide layer is removed and material chromium enriched again. Additionally iron particles originating from cold rolling, cutting or dust particles can damage the product’s surface. These particles corrode in humid air and damage the passive layer of the material. Larger particles can cause even surface defects. In both cases the corrosion resistance is reduced.
PICKLING WITH MIXED ACIDS
The best way to restore the corrosion resistance is a chemical pickling process. The surface oxide layer is removed by a controlled reaction and the chromium depleted zones will be enriched again. Pickling involves using mixed acids. These mixed acids contain nitric acid (HNO3) and hydrofluoric acid (HF).
ENVIRONMENTAL EFFECT OF MIXED ACID PICKLING
After pickling these acids need to be disposed. The waste acids containing heavy metals, nitrates and toxic fluorides represents a problematic waste which burdens the environment and causes high disposal costs. Furthermore the resources water, nitric and hydrofluoric acid being used to prepare the pickling solution are lost in the waste. Fresh resources need to be used to prepare new pickling solution.
SUSTAINABLE SOLUTIONS FOR PICKLING WITH MIXED ACIDS
SUSTEC has developed a solution which recovers all waste acid content completely. Acids and Water are recovered, as well as the metals dissolved during pickling. This new process is called REGMAX, as our solution enables a cycle of all material used during pickling.
REGMAX ensures MAXIMUM:
- acid regeneration efficiency
- metal recovery
- conservation of resources
- cost savings