Environmental Engineering Reference
In-Depth Information
Figure 11.17: Gulf chemical and metallurgical process [From ref.
567
. Reprinted with permission].
The solubilized metals are then recovered by conventional precipitation or solvent-extraction
techniques. It is reported that
>
96% of the Mo in the spent catalyst was recovered as
crystalline ammonium hepta molybdate [(NH
4
)
7
Mo
6
O
24
ยท
4H
2
O]. The recoveries of other
metals (Al, Ni, and Co) are
>
90 wt.%.
Figure 11.18 [662]
shows a general scheme for the
recovery of Al, Ni (or Co), and Mo after fusion with KHSO
4
and dissolution of the fused mass
in water. The yields of Ni, Co, Mo, and Al recovered in this process are presented in
Table 11.3 [662]
. It is claimed that the final wastes generated in this process have low toxicity
and can be sent to industrial dumps or co-processed as mineralizing agent.
