Uranium mining (open cut and underground) and milling. Chapter 6

Uranium has been mined since about 1830 as a glass and glaze colorant, but its exploitation began in earnest in the 1940s, initially for military purposes but then from the mid-1950s for fuel for nuclear power plants. Mining from underground and open cut mines has dominated production. Ore grades have ranged from over 15% to less than 0.03% U. Various milling and purification methods have been developed, nearly always employing acid or alkaline leaching of uranium from crushed and ground ore followed by one or both of solvent extraction or ion exchange, used to purify and concentrate the uranium prior to precipitation and drying. Recent production has been around 50,000 t/year expressed as uranium metal. (author)