| Mineral and solid reductant
feedstock: Use of less pure minerals; use of banded ores; high Si-containing
minerals; pelletized versus fine versus lump ore use (all associated
with different mining, tailings, and greenhouse gas footprint); minerals
that cause less environmental harm, waste, water use, and tailings
when mined; reduced mineral processing (such as sintering) prior to
use in reduction processes; moderate use of renewable biomass as reductant
(avoiding competition with food production); use of feedstock with
reduced beneficiation requirements |
| Reductant feedstock: Replacement
of fossil reductants by sustainably produced hydrogen carriers; use
of mixed reductants; reductants produced from power-to-fuel and power-to-reductant
processes (such as sustainably produced hydrogen, methane, methanol,
ammonia, etc.) |
| Mixed feedstock: Mixing
feedstock of different (cost-efficient and sustainable) origin in
reduction and smelting operations; design of reactor concepts that
can cope with flexible reductant (and mineral) charging |
| Bio-hydrometallurgical
feedstock:
Plant, fungi, and bacteria as biological feedstock in precious metal,
rare earth, nickel, and cobalt recovery via bio-leaching |
