Fluorochemical industry
[5] About 3 kg (6.6 lb) of metspar grade fluorite, added directly to the batch, are used for every metric ton of steel made.
Significant direct uses of HF include pickling (cleaning) of steel, cracking of alkanes in the petrochemical industry, and etching of glass.
[5] One third of HF (one sixth of mined fluorine) is used to make synthetic cryolite (sodium hexafluoroaluminate) and aluminium trifluoride.
The most common one, that of sodium, is used for water fluoridation, as an intermediate for synthetic cryolite and silicon tetrafluoride, and for treatment of effluents in laundries.
[9] The compound is also a component in newly devised constructions (negative index metamaterials) which are the subject of "invisibility" research.
Fluoropolymers are less than one quarter the size of refrigerant gases in terms of fluorine usage, but are growing faster.
CFCs are identified by a system of numbering that explains the amount of fluorine, chlorine, carbon and hydrogen in the molecules.
The term Freon has been colloquially used for CFCs and similar halogenated molecules, though strictly speaking this is just a DuPont brand name, and many other producers exist.
[5] Production of CFCs grew strongly through the 1980s, primarily for refrigeration and air conditioning but also for propellants and solvents.
The banning of CFCs initially depressed the overall demand for fluorite but 21st century production of the source mineral has recovered to 1980s levels.
[5] Hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) now serve as replacements for CFC refrigerants; few were commercially manufactured before 1990.
[14] A new type of fluorinated refrigerant planned to replace the high Global Warming Potential HFC compounds are hydrofluoroolefins (HFOs).
It is also used extensively in the chemical process industry where corrosion resistance is needed: in coating pipes, in tubing, and gaskets.
W. L. Gore & Associates is not the only producer of ePTFE and furthermore "Gore-Tex" often refers to more complicated multi-layer membranes or laminated fabrics.
PTFE can also be formed into fibers which are used in pump packing seals and bag house filters for industries with corrosive exhausts.
They are easier to work with (to form into complex shap es), but are more expensive than PTFE and have lower thermal stability.
[17][19][20] Fluorinated ionomers (polymers that include charged fragments) are expensive, chemically resistant materials used as membranes in certain electrochemical cells.
[17] Fluorinated surfactants are small organofluorine molecules, principally used in durable water repellent (DWR).
The largest application for elemental fluorine is the preparation of uranium hexafluoride, which is used in the production of nuclear fuels.
[28] The second largest application for fluorine gas is for the production of sulfur hexafluoride, which is used as a dielectric medium in high voltage switching stations.
Tetrafluoromethane, is used for plasma etching in semiconductor manufacturing, flat panel display production, and microelectromechanical systems fabrication.
The experiments failed because fluorine proved difficult to handle, and its combustion product (typically hydrogen fluoride) was extremely toxic and corrosive.
[33][34] Commercial producers of fluorine gas continue to use the method of electrolysis pioneered by Moissan, with some modifications in the cell design.
Several thousand metric tons of elemental fluorine are produced annually by electrolysis of potassium bifluoride in hydrogen fluoride.
If HF alone is electrolyzed, hydrogen forms at the cathode (positive part of the cell) and the fluoride ions remain in solution.
An earlier version of fluorine production process, by Moissan, uses platinum group metal electrodes and carved fluorite containers.
[36] Fluorine gas may be stored in steel cylinders where the inside surface is passivated by a metal fluoride layer that resists further attack.
In the laboratory, fluorine gas can be used in glass tubing provided the pressure is low and moisture is excluded,[37] although some sources recommend systems made of nickel, Monel, and PTFE.
[39] The main idea is that some metal fluoride anions do not have a neutral counterpart (or those are very unstable) and their acidifying would result in chemical oxidation, rather than formation of the expected molecules.
