Environmental Engineering Reference
In-Depth Information
Figure 11.16: Flow sheet for the extraction of Mo from spent catalyst by salt-roasting [ref.
658
].
11.1.2.2 Roasting with Potassium Salts
Fusion with KHSO
4
followed by water extraction has been used by Busnardo et al.
[662]
for
recovering Mo, Ni, Co, and Al from CoMo/Al
2
O
3
and NiMo/Al
2
O
3
type spent catalysts. In
this process, Mo, Ni, Co, and Al are converted into water-soluble salts of the metals during
high temperature treatment (500
◦
C) with KHSO
4
according to the following reactions:
NiO+ 2KHSO
4
⇒
NiSO
4
+K
2
SO
4
+H
2
O
CoO+ 2KHSO
4
⇒
CoSO
4
+K
2
SO
4
+H
2
O
⇒
Al
2
O
3
+ 6KHSO
4
Al
2
(SO
4
)
3
+K
2
SO
4
+H
2
O
MoO
3
+ 2KHSO
4
⇒
MoO
2
SO
4
+K
2
SO
4
+H
2
O
