Leaching Kinetios And Mechanism Of Extracting Vanadium From Single-vanlence Vanadium-bearing Stone Coal By Sulfuric Acid

The direct acid leaching of vanadium from stone coal belongs to the whole wet process.In the leaching process,neither roasting process nor any oxidant is needed as the leaching aid,which can effectively reduce the exhaust gas emissions,save resources and relieve the environmental pressure.However,the process of extracting vanadium from stone coal is complex.The traditional kinetic studies are based on the general vanadium valence.The leaching kinetic processes of different vanadium valence are not studied in detail,and the corresponding leaching kinetic mechanism is unknown.In this paper,the sulfuric acid leaching kinetics of vanadium with different valence in stone coal is studied in detail,which provides the corresponding theoretical basis for the study of clean and efficient extraction of vanadium from stone coal and the leaching kinetics of related minerals,and is of great significance to the industrialization of extraction of vanadium from stone coal.In this paper,aiming at the problem that the sulfuric acid leaching kinetics of different valences of vanadium in stone coal is unknown,the sulfuric acid leaching kinetics mechanism of different valences of vanadium in stone coal is systematically studied,taking the stone coal vanadium ore from the two places of Ramma sand mine and Baiyan mine in Western Hunan as raw materials.The research contents are as follows:Preparation of vanadium bearing stone coal samples with only one valence: after experimental analysis of +3,+4,+5-valence vanadium content in stone coal of two mining areas:(1)preparation of +3 valence vanadium bearing stone coal samples by sulfuric acid solution direct leaching method;(2)preparation of +4 valence vanadium bearing stone coal samples by roasting alkali leaching method;(3)preparation of +5valence only by high temperature roasting method Through continuous optimization of preparation conditions,different kinds of stone coal samples with single valence vanadium accounting for more than 98% of the total vanadium were prepared.Single factor experiment and orthogonal experiment of sulfuric acid direct leaching:study the leaching conditions of single valence vanadium stone coal samples,investigate the effects of different leaching conditions,such as sulfuric acid concentration,leaching reaction temperature,leaching reaction time,solid-liquid ratio,stirring rate and mineral particle size on vanadium leaching rate,and determine the best leaching conditions.In addition,the main influencing factors on the leaching reaction of vanadium from stone coal were studied by orthogonal experiment.The results show that sulfuric acid concentration and leaching temperature are the mainfactors affecting the vanadium leaching rate of +3-valent samples,and sulfuric acid concentration and leaching reaction time are the main factors affecting the vanadium leaching rate of +4 and +5-valent samples.Study on the kinetic mechanism of sulfuric acid direct leaching of single valence vanadium stone coal samples: Based on the best leaching conditions obtained by different single factor experiments,the kinetic mechanism of sulfuric acid direct leaching of single valence vanadium is studied according to the shrinking core kinetic model.The experimental results show that the leaching process of + 3-valent vanadium in stone coal is controlled by the mixed control kinetics in different sulfuric acid concentration and temperature,the leaching reaction of + 4-valent vanadium in stone coal is controlled by the solid film diffusion,and the leaching process of +5-valent vanadium in stone coal is controlled by the mixed control in different sulfuric acid concentration and temperature.