A novel sequential process of bioleaching and chemical leaching for dissolving Ni, V, and Mo from spent petroleum refinery catalyst

Recovery of Mo and Ni from spent acrylonitrile catalysts using an oxidation leaching–chemical precipitation technique

“…Numerous processes have been developed for protecting the environment and for recovering valuable metals from spent Mo-Ni catalysts Kim et al, 2009;Mishra et al, 2010;Pradhan et al, 2013;Safarzadeh et al, 2012;Wang and Wang, 2010). Hydrometallurgical processes have attracted particular interest because they are more environmentally friendly than thermometallurgical processes as a result of their lower energy requirements, lower gas emissions and smaller amounts of waste generated and because their metals can be completely recovered (Kinoshita et al, 2003;Park et al, 2012).…”

Effect of Shear Stress on Deoiling of Oil‐Contaminated Catalysts in a Hydrocyclone

“…Spent catalysts are regarded as solid wastes and have raised environmental awareness [2]. Spent catalysts containing plentiful hydrocarbon pollutants and heavy metals, e.g., V and Ni, have been tagged as hazardous wastes by the U.S. Environmental Protection Agency [3]. Owing to the implementation of stricter environmental regulations and the increase of environmental awareness, recovery and reuse of spent catalysts have become essential, particularly in the removal of hydrocarbon pollutants from oil-contaminated catalysts in a wide range.…”

Sequential biological process for molybdenum extraction from hydrodesulphurization spent catalyst

“…thiooxidans) and Acidithiobacillus ferrooxidans (At. ferrooxidans)) are also used for spent catalyst bioleaching (Mishra and Rhee, 2010;Pradhan et al, 2013;Srichandan et al, 2014). Proton (H þ ) and Fe 3þ produced by bacterial oxidation of sulphur and Fe 2þ respectively, play a significant role in metal extraction from the solid substrate.…”

“…Similarly, with At. ferrooxidans, high Ni leaching of about 90e95% was observed while Mo leaching was low (Pradhan et al, 2013). The lower Mo recovery has been attributed to the insolubility of the metal under acidic conditions and subsequent precipitation as molybdenum trioxide.…”

“…Efforts to improve Mo extraction include pretreatment of spent catalyst, microbial adaptation and use of extreme thermophiles or fungal strains (Amiri et al, 2011;Bharadwaj and Ting, 2013;Santhiya and Ting, 2006). In another approach, an additional chemical leaching step was introduced (Pradhan et al, 2013). After bioleaching with At.…”