Is compressed air the only gas used to power a jet mill?
No. Commercially, compressed air is by far the most commonly used gas but super heated steam (no moisture is present in the super heat state) is used in very large installations grinding primarily titanium dioxide pigment. Nitrogen is commonly used when a material must be ground in an inert atmosphere to protect from oxidation and possible fire or even explosion of the product. Argon has also been used for this purpose if the less expensive nitrogen was unsuitable. Light gases such as helium have been experimented with because of the possibility of even higher velocity impacts.
