Leaching of vanadium, potassium, and iron from spent catalyst of the manufacture of sulfuric acid

The sulfuric acid industry produces large volumes of spent catalyst containing vanadium. To develop an efficient method for vanadium recovery, hydrogen peroxide was used to oxidize sulfur in the spent catalyst, forming sulfuric acid, which, in turn, leached the metals from the catalyst. Experimental results showed that the leaching efficiency of vanadium gradually increased with hydrogen peroxide concentration; other parameters had minor effects. The hydrogen peroxide concentration, stirring rate, and pH had negative effects on leaching percent of potassium. Leaching efficiency of iron decreased with an increase in leaching time, stirring rate, and pH; with the increase in hydrogen peroxide concentration and liquid:solid ratio, leaching efficiency of iron first increased and then decreased. The optimum leaching conditions for vanadium were hydrogen peroxide concentration of 148 g/L, leaching time of 5 min, leaching temperature of 25 ?C, stirring rate of 300 r/m, and liquid:solid ratio of 3:1, and leaching efficiencies of vanadium, potassium, and iron were 92.2%, 48.2%, and 46.3%, respectively. For potassium and iron, the leaching efficiencies of 70.9% and 70.5% were achieved using pure water leaching under the conditions of leaching time of 30 min, liquid to solid ratio of 4:1, and the temperature of 25 ?C. ? 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC

Automated summary

In this study, hydrogen peroxide was used to oxidize the sulfur in spent catalyst, forming sulfuric acid to leach out metals. Experimental results showed that the leaching efficiency of vanadium increased with hydrogen peroxide concentration, while other parameters had minor effects on potassium and iron leaching efficiencies. The optimum leaching conditions for vanadium were identified, with high efficiencies achieved for vanadium, potassium, and iron.