Effect of activator on kinetics of direct acid leaching of vanadium from clay vanadium ore

Abstract

• A novel process for vanadium extraction from clay vanadium ore was proposed. • Activator MF is beneficial to improving leaching efficiency of vanadium. • Effects of main factors on direct activated acid leaching were discussed. • The kinetics of direct activated acid leaching of vanadium was elucidated. According to the characteristics of clay vanadium ore, a novel process of no-grinding and no-roasting direct activated acid leaching under atmospheric pressure, was proposed. And in order to improve the leaching efficiency of vanadium, new activator MF was added into the acid leaching process. The effects of main factors on acid leaching of vanadium were investigated. The results showed that the leaching efficiency of vanadium reached 96.14 % under the conditions as follows: mass ratio of manganese oxide to fluoride is 25 %: 75 %, activator dosage of 3 %, H 2 SO 4 dosage of 25 %, leaching temperature of 90 ℃, and leaching time of 5 h. The leaching kinetics was studied by using the unreacted shrinking core model. It was found that under the optimum conditions, the control step of direct activated acid leaching of vanadium from clay vanadium ore is changed from hybrid control to diffusion control, the apparent activation energy is reduced from 36.30 kJ‧mol −1 to 12.54 kJ∙mol −1 , and the reaction order of sulfuric acid is reduced from 2.9033 to 1.8114.