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Química Nova

Print version ISSN 0100-4042On-line version ISSN 1678-7064


VALVERDE JUNIOR, Ivam Macedo; PAULINO, Jéssica Frontino  and  AFONSO, Julio Carlos. Hydrometallurgical route to recover molybdenum, nickel, cobalt and aluminum from spent hydrotreating catalysts in acid medium. Quím. Nova [online]. 2008, vol.31, n.3, pp.680-687. ISSN 0100-4042.

This work describes a hydrometallurgical route for processing spent commercial catalysts (CoMo and NiMo/Al2O3). Samples were preoxidized (500 ºC, 5 h) in order to eliminate coke and other volatile species present. The calcined solid was dissolved in concentrated H2SO4 and water (1:1 vol/vol) at 90 ºC; the insoluble matter was separated from the solution. Molybdenum was recovered by solvent extraction using tertiary amines at pH around 1.8. Cobalt (or nickel) was separated by addition of aqueous ammonium oxalate at the above pH. Phosphorus was removed by passing the liquid through a strong anion exchange column. Aluminum was recovered by neutralizing the solution with NaOH. The route presented in this work generates less final aqueous wastes because it is not necessary to use alkaline medium during the metal recovery steps.

Keywords : spent catalysts; metal recovery; waste management.

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