Metal Reclamation from Spent Hydroprocessing Catalysts - Spent Hydroprocessing Catalysts - page 281

Figure 11.10: Flow sheet of the process with material balance for the recovery of molybdenum
from spent catalyst by leaching with Na 2 CO 3 +H 2 O 2 [From ref. 635 . Reprinted with permission].
stages, respectively. Maximum recoveries of 97% Mo in the first stage and 90-93% Co and Ni
in the second stage were achieved in this process within two hours of leaching at 100 ◦ C. The
Co or Ni dissolution was negligibly small ( < 0.1%) in the first stage alkali leaching. Similarly,
Mo leaching was negligible ( < 0.3%) in the second stage acid leaching. However, a substantial
amount of Al was leached in both stages (12-14% in the first stage and 55-65% in the second
stage). Sun et al. [361] used concentrated ammonia solution in the first stage and 10% H 2 SO 4
in the second stage to leach Mo and Co from the spent CoMo/Al 2 O 3 catalyst. About 83% Mo
and 77% Co together with 4% Mo were recovered, respectively, in the first and second stages.
In another related study, these authors were able to recover 83% Mo and 44% Ni in the first