Vanadium-bearing titanomagnetite concentrates were desulfurized with Acidithiobacillus ferrooxidans(A.ferrooxidans).The sulfur content of the concentrates was reduced from 0.69wt%to 0.14wt%after bioleaching for 15 d with a 10%pulp density at 30 C.Maintaining a stable pH value during biodesulfurization was critical because of high acid consumption,resulting from a combination of nonoxidative and oxidative dissolution of pyrrhotite in acid solution.It is discovered that the citric acid-disodium hydrogen phosphate bufer of pH 2.0 can control the solution pH value smoothly in the optimal range of 2.0-3.0 for A.ferrooxidans growth.Using the bufer in the volume fraction range of 5.0%-15.0%stimulates A.ferrooxidans growth and improves the biodesulfurization efciency.Compared with the bufer-free control case,the maximum increase of biodesulfurization rate is 29.7%using a 10.0vol%bufer.Bioleaching provides an alternative process for desulfurization of vanadium-bearing titanomagnetite ores. Vanadium-bearing titanomagnetite concentrates were desulfurized with Acidithiobacillus ferrooxidans (A. ferrooxidans). The sulfur content of the concentrates was reduced from 0.69 wt% to 0.14 wt% after bioleaching for 15 d with a 10% pulp density at 30 C. Maintaining a stable pH value during biodesulfurization was critical because of high acid consumption, resulting from a combination of nonoxidative and oxidative dissolution of pyrrhotite in acid solution. It is found that the citric acid-disodium hydrogen phosphate bufer of pH 2.0 can control the solution pH value smoothly in the optimal range of 2.0-3.0 for A. ferrooxidans growth. Using the bufer in the volume fraction range of 5.0% -15.0% stimulates A. ferrooxidans growth and improves the biodesulfurization efciency. Compared with the bufer-free control case, the maximum increase of biodesulfurization rate is 29.7% using a 10.0 vol% bufer.Bioleaching provides an alternative process for desulfurization of vanadium-bearing titanomagnetite ores.