US 9,809,870 B2
Process for separating and recovering metals
Rahul Shankar Bhaduri, Moraga, CA (US); Louis Joseph Nordrum, Corte Madera, CA (US); and Alexander E. Kuperman, Orinda, CA (US)
Assigned to Chevron U.S.A. Inc., San Ramon, CA (US)
Filed by Chevron U.S.A. Inc., San Ramon, CA (US)
Filed on Aug. 6, 2014, as Appl. No. 14/452,843.
Application 14/452,843 is a continuation of application No. 13/156,589, filed on Jun. 9, 2011, granted, now 8,815,184.
Claims priority of provisional application 61/374,171, filed on Aug. 16, 2010.
Prior Publication US 2014/0348729 A1, Nov. 27, 2014
This patent is subject to a terminal disclaimer.
Int. Cl. C22B 34/34 (2006.01); C22B 34/22 (2006.01); C22B 3/00 (2006.01); C22B 7/00 (2006.01)
CPC C22B 34/345 (2013.01) [C22B 7/009 (2013.01); C22B 23/0446 (2013.01); C22B 34/225 (2013.01); Y02P 10/214 (2015.11); Y02P 10/23 (2015.11); Y02P 10/234 (2015.11)] 29 Claims
OG exemplary drawing
 
1. A method for recovering metals from a spent catalyst, the method comprising:
leaching a Group VIB metal, a Group VIII metal, and a Group VB metal, from the spent catalyst with an ammonia containing leach solution at a temperature and a pressure sufficient to form a pressure leach slurry;
separating and removing a solid residue from the pressure leach slurry to form a pressure leach solution comprising a Group VIB soluble metal complex and a Group VIII soluble metal complex;
treating the pressure leach solution by chemical precipitation to precipitate at least a portion of the Group VIB metal and at least a portion of the Group VIII metal as precipitated metal complexes;
recovering the precipitated metal complexes by at least a separation means selected from settling, filtration, decantation, centrifugation and combinations thereof, forming a first effluent stream containing less than 600 ppm of the Group VIB metal and less than 400 ppm of the group VIII metal and a solid residue containing at least 97% of incoming Group VIB metal and over 80% of incoming Group VIII metal;
sulfiding the first effluent stream with a sulfiding agent to form a sulfided slurry comprising a Group VB metal sulfide and/or oxide, a Group VIB metal sulfide and a Group VIII metal sulfide;
separating and removing the Group VB metal sulfide and/or oxide, the Group VIB metal sulfide and the Group VIII metal sulfide from the sulfided slurry, forming a second effluent stream comprising a Group VB and a Group VIB soluble metal compound;
contacting the second effluent stream with an effective amount of ferric ion at a pre-selected pH for the ferric ion to form a complex with the Group VB and Group VIB metal;
performing a liquid-solid separation to remove the Group VB and Group VIB metal complex as solids, forming a third effluent containing less than 10 ppm of the Group VB metal and less than 10 ppm of Group VIB metal.