The Key Lake mine is a former uranium mine in Saskatchewan, Canada. It is north of Saskatoon by air on the southern rim of the uranium-rich Athabasca Basin. Key Lake was initially developed to open-pit mine two nearby uranium ore deposits: the Gaertner deposit and the Deilmann deposit. Mining of this ore ceased in the late 1990s; the Key Lake mill now processes uranium ore from the McArthur River mine and from existing stockpiles on site. High-grade ore from McArthur river is blended with lower grade local rock before being passed through the mill. The mill has a permitted annual production capacity of 25 million pounds of U3O8. In addition, ammonium sulfate fertilizer is produced as a byproduct from used reagents. The pits of the mined out local deposits are being used as mill tailings management facilities.