Conc. KOH, M | Leaching efficiency, % | ||||
Nb | Ta | REE | Ti | Zr | |
6 | 72 | 73 | 75 | 66 | 5 |
8 | 81 | 80 | 81 | 73 | 6 |
10 | 87.5 | 85 | 89 | 79 | 9 |
12 | 87 | 84 | 86 | 74 | 9 |