On-site Production of Hydrogen Peroxide for Hydrometallurgical Leaching of Black Mass
Andersson, Max (2024)
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe2024090969969
https://urn.fi/URN:NBN:fi-fe2024090969969
Tiivistelmä
Hydrogen peroxide can be used as a reducing agent in the hydrometallurgical leaching of black mass from spent lithium-ion batteries. Currently, hydrogen peroxide is mainly produced with the energy-intensive anthraquinone process. The production is performed in centralized facilities, requiring organic chemicals and stabilization additives while posing significant transportation hazards and costs.
This thesis explores methods for the on-site production of hydrogen peroxide. On-site and decentralized hydrogen peroxide production removes the need for transport and additives. It offers significant economic and environmental benefits, making it a more sustainable alternative to externally sourced hydrogen peroxide.
In the literature review, research into the electrosynthesis of hydrogen peroxide showed that the electrosynthesis technology was not mature enough for industrial applications. As a result, the focus was turned toward converting existing sulfuric acid streams using the Weissenstein process. The Weissenstein process involves the electrolysis of sulfuric acid to produce persulfate (S2O82−) and hydrolysis of persulfate to produce hydrogen peroxide. An experimental setup was first developed, and the resulting setup was applied to investigate the effect of the amount of persulfate on the concentration of obtained hydrogen peroxide.
As a result, the highest hydrogen peroxide concentration achieved was 1.2 wt-% by hydrolyzing a 20 wt-% ammonium persulfate sample solution. The hydrolysis reactions achieved up to 72% yields, with low sulfate amounts in the condensate. A long enough contact time between water and ammonium persulfate was vital for achieving high hydrogen peroxide yields. Furthermore, analyses of the obtained oxidant showed that persulfate was not obtained in the condensate. Although relatively high yields were obtained, challenges in reproducibility and equipment limitations emphasized the need for a dedicated distillation apparatus to accurately study the reaction kinetics and further enhance the yield. In the end, an industrial process flow scheme for the integration of on-site hydrogen peroxide production into black mass leaching processes, is proposed. The proposed flow scheme suggested recirculation of unreacted persulfate to improve overall yield of the process.
This thesis explores methods for the on-site production of hydrogen peroxide. On-site and decentralized hydrogen peroxide production removes the need for transport and additives. It offers significant economic and environmental benefits, making it a more sustainable alternative to externally sourced hydrogen peroxide.
In the literature review, research into the electrosynthesis of hydrogen peroxide showed that the electrosynthesis technology was not mature enough for industrial applications. As a result, the focus was turned toward converting existing sulfuric acid streams using the Weissenstein process. The Weissenstein process involves the electrolysis of sulfuric acid to produce persulfate (S2O82−) and hydrolysis of persulfate to produce hydrogen peroxide. An experimental setup was first developed, and the resulting setup was applied to investigate the effect of the amount of persulfate on the concentration of obtained hydrogen peroxide.
As a result, the highest hydrogen peroxide concentration achieved was 1.2 wt-% by hydrolyzing a 20 wt-% ammonium persulfate sample solution. The hydrolysis reactions achieved up to 72% yields, with low sulfate amounts in the condensate. A long enough contact time between water and ammonium persulfate was vital for achieving high hydrogen peroxide yields. Furthermore, analyses of the obtained oxidant showed that persulfate was not obtained in the condensate. Although relatively high yields were obtained, challenges in reproducibility and equipment limitations emphasized the need for a dedicated distillation apparatus to accurately study the reaction kinetics and further enhance the yield. In the end, an industrial process flow scheme for the integration of on-site hydrogen peroxide production into black mass leaching processes, is proposed. The proposed flow scheme suggested recirculation of unreacted persulfate to improve overall yield of the process.