Study on leaching behavior of vanadium in acid leaching process of calcium and manganese vanadate system
Calcium vanadate and manganese vanadate are important roasting products in the calcifica-tion roasting process of vanadium slag,and their dissolution and leaching behavior in sulfuric acid has an important effect on the vanadium yield in the vanadium extraction process.In this paper,the effects of leaching pH,time and temperature on the leaching behavior of vanadium components in the synthes-is of calcium vanadate(or manganese vanadate),vanadium slag calcification(or reaction with man-ganese)and calcium-manganese composite roasting clinker were studied by single factor test step-by-step method.The results showed that the maximum leaching rate of vanadium was 43.62％,98.79％,97.98％ and 98.06％ when the synthetic CaV2O6,Ca2V2O7,Ca3V2O8 and Mn2V2O7 were leached at 60℃for 60 min at pH 3.0,3.0,5.0 and 2.2,respectively.When the pH value is 1.0～2.0,the leaching rate of the four vanadates shows a low peak,which is caused by the hydrolysis of vanadium.Ca2V2O7 and Mn2V2O7 vanadate were mainly formed during the conventional calcification and manganese roasting of vanadium slag,and the leaching rates of vanadium were 85.24％and 87.07％,respectively,when the leaching pH value was 2.5.The leaching rate of vanadium after clinker leaching in sulfuric acid solu-tion with pH value of 2.5 was 90.09％,which was about four percentage points higher than that of vana-dium in conventional calcification and manganese systems,indicating that the synergistic extraction of vanadium from calcium and manganese had a certain strengthening effect on vanadium extraction with a single additive.
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