Recovering valuable metals from spent hydrodesulfurization catalyst via blank roasting and alkaline leaching

Techno-economic feasibility of a recycling plant for the extraction of metals and boehmite from hazardous petroleum spent catalysts

Petroleum spent hydroprocessing catalysts are hazardous solid waste, the efficient recycling of which is a serious challenge to refineries. However, information on the economic feasibility of spent catalysts recycling plants is scarce, which is critical for environmental authorities and decision-makers. In this work, an innovative recycling scheme targeting hydrometallurgical recovery of base metals (Ni, Mo, and V) and transforming low-value Al residue into a high-value boehmite (γ-AlOOH) as the key product was considered an efficient way to beneficiate the hazardous spent hydroprocessing catalysts. A preliminary techno-economic evaluation of such a recycling scheme was performed to assess the feasibility of the proposed recycling scheme. The recovery cost (valuable metals and boehmite) and potential revenue were estimated to study the economics of the process. The preliminary results have suggested that the recycling scheme is economically feasible with a high internal rate of return (IRR) of 12.3%, a net present value of 38.6 million USD, and a short payback period of 8.7 years. Furthermore, a sensitivity analysis (± 10%) conducted on key parameters showed that the selling prices of the finished products and the cost of chemicals were the most important factors affecting plant economics. Overall, the recycling scheme was sustainable and avoided landfilling of spent catalysts as the residue can be beneficiated into a high-value product. The results from the economic feasibility study are likely to assist the stakeholders and decision-makers in making investment and policy decisions for the valorization of spent hydroprocessing catalysts.

Thermodynamic analysis and application for extracting valuable components from iron-phosphorus residue of spent catalysts

The method of extracting valuable metals from spent catalysts has been developed in recent years. In this paper, the solid waste produced in the treatment of spent catalyst was studied and named iron-phosphorus residue (IPR). IPR was composed of FePO4·2H2O, Fe3(PO4)2·3H2O, Fe5(PO4)4(OH)3·2H2O, and SiO2. Appreciable quantities of Ni, Co, V, Mo, and W were detected in IPR. Based on E-pH diagrams, different atmospheric leaching strategies were used to extract valuable components from IPR. Both the HCl and NaOH leaching are appropriate for treating IPR. An in-depth investigation on HCl atmospheric leaching showed that >95% of Fe, Ni, Co, V, and Mo, 76.9% of W, and 89.3% of P were extracted efficiently and SiO2 was enriched into the leach residue, at leaching temperature of 90 ℃, leaching time of 180 min, initial HCl concentration of 5 mol/L and liquid to solid ratio of 8:1 mL/g. The leaching mechanism was discussed via XRD, XPS, and FTIR. An efficient and green process for the recovery of valuable components in IPR has been developed. This research achieves the sufficient extraction of valuable components in IPR and provides significant guidance for the management of similar solid waste.