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Recovery of calcium fluoride as a secondary resource for fluoro polymer production

Strategy

The supply of the mineral fluorite for industrial use is classified as critical. Europe is dependent on imports for this raw material and at the same time fluorite is being used in more and more key products. Fluorite is used as an additive for molten metals and is needed for hydrofluoric acid and fluoropolymer production, such as PTFE (polytetrafluoroethylene).

The aim of the project is to develop a flexible, environmentally friendly, high-performance process which makes it possible to convert fluorocarbon wastes into synthetic, high-quality fluorite. This fluorite shall then be directly included into value-added production as a secondary resource. The first step in this new approach to recover fluoride from organic compounds is to convert fluoropolymers and small molecular waste materials into CO2, HF and H2O. This takes place within an autothermic high-temperature conversion process. The transformation of the gaseous mixture into synthetic fluorite is induced by a reaction with limestone (CaCO3). The resulting fluorite is added to natural fluorspar and is then converted together with sulfuric acid into anhydrous HF using a conventional rotary kiln. To ensure direct use of the synthetic fluorite, the resulting material must be of high purity and have a narrow particle size distribution.

Contribution to the sustainability and/or the security of supply

In the first place, partially fluorinatedpolymers have the highest potential as an end-of-life recycling material. Closing the fluorine cycle for fluoropolymers by recycling the fluorine in the form of CaF2 would not only provide a secondary source of the ever more expensive fluorite, but could also be an alternative to the increasingly complicated waste management of fluorinate materials.

Utilization cycle of synthetic fluorite
Utilization cycle of synthetic fluorite

Project goals:
- Recycling of partially fluorinated polymers into raw materials
- Production of synthetic fluorite as a secondary resource for hydrofluoric acid production

Project partner:
University of Bayreuth
3M Dyneon GmbH