Environmental Engineering Reference
In-Depth Information
Figure 11.23: TAIYO KOKO process [From ref.
692
. Reprinted with permission].
11.3.6 Moxba-Metrex Process
Moxba-Metrex, which is a Dutch Company specialized in the processing of spent catalysts and
metal containing residues, recovers all major metals present in spent hydroprocessing catalyst
by sulfuric acid leaching process
[311,693]
. Prior to the leaching, the spent catalyst is decoked
in a furnace. The metal oxides are then dissolved in the acid leaving the alumina support as
residue which is separated by means of decanting, washing and filtration from the liquor
containing metals. The metals are isolated from the liquor by solvent extraction carried out in
several stages, i.e. the first Mo, followed by V, Co, and Ni. MoO
3
is sold to steel industry
whereas ammonium molybdate and vanadate are sold as intermediate chemicals. Co and Ni
