Current background

With the standardized development of the global waste lithium-ion battery recycling industry and the continuous improvement of quality requirements for recycled materials, effective control of fluorine content in black powder has become one of the core challenges in the industry. International standards and practices usually distinguish fluorine in black powder into water-soluble fluorine and acid soluble fluorine, which have significant differences in source, characteristics, and environmental impact, directly affecting lithium recovery rate and production and operation safety. This article combines the requirements of international standards to deeply analyze the core technical principles and process optimization paths of defluorination of black powder.

Why do we need to defluorinate lithium battery black powder

1、Avoiding the generation of hydrofluoric acid during the acidic leaching process significantly reduces interference with the process flow and the risk of corrosion to reactors and pipelines.
2、By effectively removing fluoride, the leaching efficiency of key metals (especially lithium) is improved, ensuring the economic value of black powder recycling.

Optimization scheme for defluorination of black powder
1、Low temperature drying process route: adding independent pyrolysis unit and calcium agent feeding system

To address the issue of insufficient defluorination capacity in the low-temperature physical recovery route, it is recommended to install an independent pyrolysis reactor and supporting tail gas treatment device outside the main process. The core optimization point lies in the precise addition of calcium hydroxide during the pyrolysis stage, which converts soluble/volatile fluorides into stable CaF ₂ through chemical reactions. This not only efficiently controls water-soluble fluorine, but also inhibits the generation of acid soluble fluorine, while simultaneously improving the comprehensive recovery rate of lithium.

2、Medium high temperature pyrolysis process route: precise reagent addition strategy at the feed end

For production lines with medium to high temperature pyrolysis capabilities, they already have a certain foundation for defluorination. The optimization focuses on achieving uniform and precise feeding of calcium hydroxide through the feed inlet of the pyrolysis device. This scheme can fully mix additives with black powder, instantly fix fluoride during the pyrolysis process, enhance the fixation effect on acid soluble fluoride, further reduce the total fluoride content, and do not require large-scale modification of existing core equipment.

Outlook on the trend of defluorination of black powder under the framework of international standards

Against the backdrop of increasingly strict global requirements for recycled materials, precise classification and control of fluorine in black powder have become inevitable. The single control of acid soluble fluoride index is no longer sufficient to meet the dual goals of efficient and compliant production. The pyrolysis process has been proven to be an effective means of controlling water-soluble fluorine, and the “pyrolysis fixation” integrated solution combining it with calcium based additives can achieve synergistic control of water-soluble fluorine and acid soluble fluorine, which is currently the most technically and economically feasible defluorination pathway.

Whether based on low-temperature drying or medium high temperature pyrolysis, effective control of fluoride content can be achieved through targeted process optimization and precise reagent management. This not only meets the requirements of international standards for product quality and environmental protection, but also significantly enhances the market value and application prospects of recycled black powder. In the future, black powder defluorination technology will continue to evolve towards “process integration, reagent efficiency, and cost optimization”, providing key support for the global resource utilization and green low-carbon transformation of waste lithium batteries.