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Determination of Vanadium Valency in Roasted Stone Coal by Separate Dissolve-Potentiometric Titration Method

Published online by Cambridge University Press:  24 February 2012

Bao Shenxu ,
Zhang Yimin ,
Hang Jing ,
Yang Xiao  and
Hu Yangjia
Bao Shenxu
Affiliation:
Hubei Key Laboratory of Mineral Resources Processing and Environment, Wuhan University of Technology, Wuhan, 430070, PR China. E-mail: sxbao@whut.edu.cn
Zhang Yimin
Affiliation:
Hubei Key Laboratory of Mineral Resources Processing and Environment, Wuhan University of Technology, Wuhan, 430070, PR China. E-mail: sxbao@whut.edu.cn College of Resources and Environmental Engineering, Wuhan University of Science and Technology, Wuhan, 430081, PR China.
Hang Jing
Affiliation:
College of Resources and Environmental Engineering, Wuhan University of Science and Technology, Wuhan, 430081, PR China.
Yang Xiao
Affiliation:
College of Resources and Environmental Engineering, Wuhan University of Science and Technology, Wuhan, 430081, PR China.
Hu Yangjia
Affiliation:
Hubei Key Laboratory of Mineral Resources Processing and Environment, Wuhan University of Technology, Wuhan, 430070, PR China. E-mail: sxbao@whut.edu.cn
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Abstract

Stone coal is an important vanadium-bearing resource in China. Most vanadium exists in stone coal as V(III), which is stable and not easily to be extracted. The V(III) should be oxidized to V(IV) and/or V(V) by roasting with additives at high temperature and then extracted by acid leaching and/or water leaching. Hence, the vanadium valency in roasted stone coal can reflect the roasting efficiency and leaching rate. In traditional digestion process, the V(V) can oxidize V(III) in solution and this causes great error to the determination of vanadium valency. In this study, the V(IV) and V(V) in roasted stone coal is dissolved firstly in 5% of hydrochloric acid at room temperature for 1h because the V(III) embedded in crystal lattice can not dissolve in dilute acid. The acid solution containing V(IV) and V(V) is titrated by 0.02 M ammonium ferrous sulfate (AFS), and the jump in titration curve indicates the reducing of V(V) to V(IV) by ferrous ion. The volume of V(V) can be calculated according to the consumption of AFS. The total volume of vanadium can be determined by potassium permanganate oxidation-ammonium ferrous sulfate titrimetric method. Hence, the volume of V(IV) can be obtained by deducting the quantity of V(V) from the total vanadium. Secondly, the undissolved residue is digested in Teflon vessel by phosphoric acid and hydrofluoric acid at 90 °C for 2h. The digestion solution is also titrated by AFS under nitrogen atmosphere, and the jump in titration curve denotes the reducing of V(IV) to V(III) by ferrous ion in phosphoric acid medium. So, the volume of V(III) and V(IV) can be obtained in the same way. This method is characterized by high measuring accuracy and excellent reproducibility.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1380 , 2012 , imrc2011-1380-s21-full013
Copyright
Copyright © Materials Research Society 2012

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References

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