Environmental Engineering Reference
In-Depth Information
time, metal recovery with organic agents is conducted under rather mild conditions, which are
free of corrosive environment. Therefore, a much higher level of safety precautions has to be
taken in the case of the methods that are based on the use of strong acids, bases, and chlorine
than that of the organic agent. Also, material requirements on the design and construction of
equipment used for the recovery are rather different. The fluctuation in metal prices on the
world market introduces some uncertainties in metal reclamation. Therefore, a more
comprehensive approach to metal reclamation from spent catalysts may be necessary.
Ultimately, this should benefit both refiner and metal reclaiming company.
One may anticipate that landfills will continue to be scrutinized by regulatory authorities. It is
believed that new and more stringent regulations will be implemented. Advancement in
chemical analysis may lead to discovery of new contaminants, which previously were either
overlooked or were undetected. This will require modification of regulatory acts, e.g.,
comprehensive liability act. Therefore, avoiding landfilling, as much as possible, may be the
best recommendation to petroleum refiners. Thus, even after a costly pretreatment of spent
catalyst before landfilling, their long-term stability in landfills has not yet been clearly
determined. It is anticipated that recycling of spent catalysts will gain increasing momentum in
the future. Continuous research in this area is needed for improving the technologies currently
available and for developing new technologies. This redissolution phenomenon was, however,
limited by the low solubility of this Anderson HPA. In the case of the CoMoP dried catalyst
(P/Mo ratio greater than 0.4), characterization of the additive containing catalyst evidenced
PCoMo
11
O
407
−
formation. Redissolution and redispersion of the active components of the
catalyst by chelating agents, thus, appeared to be responsible for the activity enhancement.
