O/R ratio | Leaching efficiency, % | ||||
Nb | Ta | REE | Ti | Zr | |
1/1 | 72.1 | 70.5 | 78 | 61.5 | 5 |
1/2 | 95.0 | 93.7 | 96 | 75 | 10 |
1/3 | 90.2 | 88 | 91 | 71 | 10 |
1/4 | 88.8 | 82 | 87 | 68.2 | 9.5 |