the Secretary of Defense shall seek to award not less than 30 percent of the total amount of grants awarded during that fiscal year for projects relating to secondary recovery of critical minerals and metals. (e) Authorization of appropriations There are authorized to be appropriated to the Secretary of Defense $50,000,000 for each of fiscal years 2021 through 2024 to carry out the grant program established under subsection (a). (f) Definitions In this section: (1) Critical minerals and metals The term critical minerals and metals means cerium, cobalt, dysprosium, erbium, europium, gadolinium, graphite, holmium, lanthanum, lithium, lutetium, manganese, neodymium, praseodymium, promethium, samarium, scandium, terbium, thulium, ytterbium, and yttrium. (2) Secondary recovery The term secondary recovery means the recovery of minerals and metals from discarded end-use products or from waste products produced during the metal refining and manufacturing process, including from mine waste piles, acid mine drainage sludge, or byproducts produced through legacy mining and metallurgy activities.