Recovery Of Zinc from Scrap Steel Using Zinc-Bromine Battery Technology

Area of Science:

• Materials Science
• Electrochemistry
• Metallurgical Engineering

Background:

• Steel recycling significantly reduces CO2 emissions but is hindered by nonferrous metal contaminants like zinc.
• Blast furnace and electric arc furnace steelmaking have a low tolerance for zinc (<0.02 wt%) in scrap.
• Efficient zinc removal is crucial for improving steel recycling rates and sustainability.

Purpose of the Study:

• To investigate a clean and efficient method for recovering zinc from steel substrates.
• To develop and test a custom-made, membrane-free, non-flow zinc-bromine battery (ZBB) for zinc removal.
• To assess the feasibility of ZBB technology for enhancing steel scrap purification.

Main Methods:

• Utilized a custom-built, membrane-free, non-flow zinc-bromine battery (ZBB) for zinc recovery from steel.
• Characterized cell performance using charge-discharge profiles.
• Analyzed zinc removal and recovery using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS).

Main Results:

• The ZBB cell achieved >99.9 wt% zinc removal from steel surfaces.
• Zinc was successfully re-electroplated onto a carbon foam electrode with high purity upon recharging.
• The process demonstrated robustness over 30 cycles, with a critical cutoff voltage of 0.5 V identified to prevent iron co-extraction.

Conclusions:

• The developed ZBB technology offers an efficient and clean method for zinc recovery from steel surfaces.
• This process can significantly improve the quality of steel scrap, facilitating higher recycling rates.
• The findings support a two-stage process for zinc recovery from complex scrap steel resources, benefiting the steel industry.