Chapter 11 - Metal Reclamation from Spent Hydroprocessing Catalysts

Abstract

Considering stringent environmental and safety regulations, metal recovery from spent catalysts is a more attractive option than landfilling. Metals such as Mo, Ni, Co, and V are highly valuable and are used extensively in the steel industry and in the manufacture of special alloys. They are usually manufactured from the ores and minerals containing them. Spent hydroprocessing catalysts could be used as a cheap source for these valuable metals. There are several studies that focus on recovery of Mo, Ni, V, and Co from the spent hydroprocessing catalysts. In addition, several companies are established for large-scale reclamation of metals and metal compounds from spent hydroprocessing catalysts. This chapter discusses reclaiming metal from spent hydroprocessing catalysts. It reviews the information available in the literature both on the laboratory studies and industrial scale processes for recovery of metals from spent hydroprocessing catalysts. Most of the studies on recovery of metals from spent hydroprocessing catalysts involve leaching with the solutions of both inorganic and organic agents. Leaching with the aid of a microorganism, i.e., bioleaching, is attracting attention as well. The dissolution of metals in water may also be enhanced by roasting spent catalysts with compounds containing alkali metals, such as sodium and potassium. Two-stage processes may employ both leaching and roasting. The volatilization or dissolution of metals of interest can be enhanced by chlorination. Attempts are made to develop novel methods, which could be competitive with conventional methods for metal reclamation.