Extraction and Recovery of Metals from Spent HDS Catalysts: Lab- and Pilot-Scale Results of the Overall Process

Abstract

The present study proposes an overall recycling process for spent hydrodesulfurization (HDS) catalysts. These catalysts contain valuable metals like cobalt (Co), molybdenum (Mo), nickel (Ni), and vanadium (V). In particular, one Co-Mo catalyst was treated in order to optimize the roasting step (time, soda ash, and temperature) at a pilot scale and thus maximize the extraction yield of molybdenum (Mo) and vanadium (V). In particular, a dry Co-Mo catalyst was used. After roasting at 700 °C for 2.5 h, the best conditions, the catalysts underwent water leaching, separating Mo and V from Co and the alumina carrier, which remained in the solid residue. The pregnant solution was treated to remove arsenic (As) and phosphorus (P), representing the main impurities for producing steel alloys. V was precipitated as NH4Cl, and further calcined to obtain commercial-grade V2O5, whereas Mo was recovered as molybdic acid by further precipitation at a pH of around one. Thus, molybdic acid was calcined and converted into commercial-grade MoO3 by calcination. The hydrometallurgical section was tested on a lab scale. The total recovery yield was nearly 61% for Mo and 68% for V, respectively, compared with their initial concentration in the spent Co-Mo catalysts.

Regeneration of Spent Nickel Catalyst via Hydrometallurgical Method

“…To achieve the desired leaching efficiency, the lixiviant must have a higher concentration, the leaching time should be longer, or the temperature should be elevated. However, to maintain the eco-friendliness and safety level of the process, recycling of leaching residue and the acid solution should be preferred or recommended for future research [5][6][7][8][9][10].…”

“…For example, to achieve high selectivity and leaching efficiency, high-temperature soda-assisted roasting is applied as a pretreatment process. Leaching using organic acids is also an interesting topic, however the leaching process requires high leaching temperatures, long leaching time, and a high amount of solvent, resulting in high acid consumption per gram of recovered nickel [7][8][9][10]. This study aims to regenerate nickel oxide from a spent nickel catalyst.…”

Correction: Xhaferaj, N.; Ferella, F. Extraction and Recovery of Metals from Spent HDS Catalysts: Lab- and Pilot-Scale Results of the Overall Process. Metals 2022, 12, 2162

“…In the original publication [1], acknowledgments to the Orim company were included. In the new version, that paragraph was removed.…”

“…In the publication [1], there were errors regarding the affiliations. In the new version, affiliation 4 has been removed and affiliation 2 has been replaced with the following: "School of Pharmacy, University of Camerino, Via S. Agostino 1, 62032 Camerino, Italy".…”

Advanced Technologies in Bio/Hydrometallurgy for Recovery and Recycling of Metals

“…The extraction and recovery of metals from spent hydrodesulfurization catalysts have been studied, for which lab-and pilot-scale results were achieved in the overall process [3]. These catalysts contain valuable metals as cobalt (Co), molybdenum (Mo), nickel (Ni), and vanadium (V).…”