Extraction of nickel from spent reforming catalyst through bioleaching with mesophilic and moderately thermophilic cultures

Considering the strategic relevance of nickel in a variety of industries, it is crucial to discover a method for extracting it from secondary sources. Spent reforming catalysts are hazardous to the environment, and require proper waste management techniques. In this research, the extraction of nickel from spent catalysts was studied and it was discovered that this process can dissolve a significant amount of nickel. Due to the high calcite content in the sample, its dissolution led to an elevation in pH, which negatively impacted bioleaching. It was observed that when the sample was added to the bioleaching solution after bacterial growth, the pH of the solution elevated less, and recovery improved. Moderately thermophilic bacteria had a better capability to reduce the pH and showed ۶۶% nickel recovery which was slightly higher than the ۶۱% recovery observed with mesophilic bacteria. Leaching tests and XRD analysis revealed that the portion of the nickel that is in the NiO phase is resistant to conventional leaching or bioleaching treatment, but reducing the sample with H۲ as the pretreatment process can enhance the recovery of nickel. Reductive pretreatment of the sample can improve recovery, however it is not advised since it may have adverse environmental implications. The toxicity assessment test revealed that the bioleaching process with both cultures is able to reduce the risk of catalyst waste.

کلیدواژه ها:

Bioleaching ، Mesophile ، Thermophile ، Reforming catalyst ، nickel