Borçelik Continuous Pickling Line Acid, Water Scenarios

Borçelik Continuous Pickling Line Acid, Water Scenarios

Borçelik processes 1.5 million tons of flat steel annually through its cold rolling and galvanizing lines. The production process begins with pickling, in which iron oxide and other metal oxides on the steel surface are removed using a hydrochloric acid bath (16–18% concentration).

Over time, the acid becomes saturated with dissolved metals and loses its effectiveness. Rather than being discarded, it is regenerated in a fluidized bed regeneration system that removes iron oxides. However, this process does not efficiently remove copper compounds. When copper accumulates in the acid, it can leave visible stains on the steel surface, leading to product quality issues.

After pickling, the steel is rinsed with high-purity water to eliminate acid residues. This rinsing process accounts for approximately 10% of Borçelik's total water consumption. The resulting wastewater is reused in earlier process steps, enhancing water efficiency.

As part of its continuous improvement efforts, Borçelik is currently exploring two innovation areas through collaboration with European stakeholders:

1.      Resource Recovery: Developing systems to recover either hydrochloric acid from the pickling process as an alternative to or in support of the conventional regeneration system or the relatively clean water from the final rinsing step,

2.      Selective Metal Separation: Designing an effective method to selectively remove dissolved copper from the acid bath, with/without interfering with iron removal.

These developments aim to improve resource efficiency, reduce operational costs, and enhance product quality.

Key Technical Challenges:

·       High corrosiveness of hydrochloric acid, which leads to rapid wear of equipment used in recovery systems.

·       Difficulty in separating chlorides from water using conventional methods, which limits the reuse potential of rinse water.

·       Low selectivity in metal removal: In hydrochloric acid, iron reacts more actively than copper, making it technically challenging to remove copper without disrupting iron chemistry.

Borçelik seeks innovative partners, solutions, or pilot technologies that can help overcome these limitations and support the company’s environmental and operational goals.