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

The authors would like to make the following corrections about the published paper [1]. The changes are as follows:

(1) 

Removal of Authors

The names of Fabio Maggiore and Nicolò M. Ippolito were removed because these authors did not want to be included in the new version due to a precedent that occurred with the Orim company. The corrected Author Contributions statement appears here.

Author Contributions: Conceptualization, N.X.; methodology, F.F.; data curation, N.X.; writing—original draft preparation, N.X.; writing—review and editing, F.F.; supervision, F.F. All authors have read and agreed to the published version of the manuscript.

(2) 

Affiliations Correction

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”. The updated affiliation information can be seen in the affiliation part of this correction.

(3) 

Removal of Acknowledgments

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

(4) 

Text Correction

A correction was made to the Abstract section. The following lines were added to the Abstract, Lines 2–4: “The process put together stages already known in the technical literature, tested again with samples coming from the roasting stage in a pilot kiln, which is the most limiting stage of metal recovery from spent catalysts”.

A correction was made to the Section 2.1, Paragraph 1. The following lines were removed: “The catalyst samples used in this work were provided by Orim SpA, a company located in Macerata, Italy”.

(5) 

References

We removed the old references [20,21], and added a new reference [22]. The citation has now been inserted in Section 1, Paragraph 2 and should read:

Various methods for recovery of HDS catalysts have been proposed in the literature: acid leaching followed by solvent extraction [11], primary leaching of spent catalyst, and then separation of metals through selective precipitation [12] recovery from biotechnological routes [13,14], carbon adsorption [15], polyelectrolyte extraction [16] and solvent extraction [17–19]. To all methods mentioned above, the recovery of metals was at different rates; however, the extraction of metals can achieve around 90% [11–13]. Presently, vanadium recovery is always greater than 90% concerning the concentration in spent catalysts [8,20]. Considering that these catalysts contain sulfur, coke, and sometimes hydrocarbons like naphtha, a thermal pre-treatment is required to convert these metals into oxides and enhance the leaching yield. The hydrometallurgical way is still the most used over the pyrometallurgical one [21]. Spent HDS catalysts are classified as hazardous materials: their disposal causes environmental threats because of the potential release of heavy metals into the soil and the groundwater table [20–22].

An old reference was replaced:

10. Le, M.N.; Lee, M.S. A Review on Hydrometallurgical Processes for the Recovery of Valuable Metals from Spent Catalysts and Life Cycle Analysis Perspective. Min. Proc. Ext. Met. Rev. 2021, 42, 335–354.

replace to

10. Feng, J.; Yan, S.; Zhang, R.; Gu, S.; Qu, X.; Bi, J. Recycling and reuse performance of cobalt catalyst for coal hydrogasification. Fuel 2023, 335, 126939. https://doi.org/10.1016/j.fuel.2022.126939.

A new reference was added:

22. Le, M.N.; Lee, M.S. A Review on Hydrometallurgical Processes for the Recovery of Valuable Metals from Spent Catalysts and Life Cycle Analysis Perspective. Min. Proc. Ext. Met. Rev. 2021, 42, 335–354.

With these corrections, the order of some references have been adjusted accordingly. Therefore, the total number of references is now 56.

The authors state that the scientific conclusions are unaffected. This correction was approved by the Academic Editor. The original publication has also been updated.