A system and method for preparing high-purity low-valent vanadium oxides by chlorination

Abstract

The invention belongs to the field of chemical industry and metallurgy, and provides a system and a method for preparing a high-purity and low-valent vanadium oxide through a chlorination method. According to the method, an industrial grade vanadium oxide is converted into vanadium oxytrichloride by using fluidization chlorination; two-stage dust removing and three-stage leaching are performed toobtain crude vanadium oxytrichloride; and rectification, catalytic oxidation and precise reduction control are performed to obtain the high-purity and low-valent vanadium oxide, wherein the average valence of vanadium can be any one selected from 3.0-4.5. According to the present invention, the furnace temperature is controlled by spraying the vanadium oxytrichloride mud into the chlorination fluidized bed; the reaction efficiency is improved by arranging the inner member on the catalytic oxidation fluidized bed; the reduction degree is regulated by arranging the vertical baffle and the material discharging ports with different heights on the reduction fluidized bed so as to obtain the high-purity and low-valent vanadium oxide with the specific valence; and the system and the method have advantages of strong raw material adaptability, no pollution, low production energy consumption, low operation cost, stable product quality and the like, are suitable for the large-scale industrial production of high-purity and low-valent vanadium oxide with more than 4N, and have good economic and social benefits.

Description

technical field [0001] The invention belongs to the fields of chemical industry and metallurgy, and particularly relates to a system and method for preparing high-purity and low-valent vanadium oxide by a chlorination method. Background technique [0002] Low-valent vanadium oxides, including vanadium trioxide and vanadium dioxide, are important industrial vanadium products and are widely used in the production of alloy additives such as ferrovanadium and vanadium nitride, as well as catalysts, colorants, and cemented carbide additives. With the continuous development of new energy technologies, the battery industry has an increasingly strong demand for high-purity and low-priced vanadium oxides (purity above 3N5), including all-vanadium redox flow batteries (VRBs) with good large-scale energy storage performance and electric vehicles. Vanadate-based lithium-ion batteries, etc. However, the existing industrial technology can usually only prepare low-valent vanadium oxides w...

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Problems solved by technology

This patent has the following deficiencies: (1) Similar to the aforementioned Iowa State University research, this patent actually only provides the principle process of chlorination and lacks specific operable solutions. For example, the chlorination method includes boiling chlorine chlorination, including molten salt chlorination, and molten salt chlorination and boiling chlorination are completely different chlorination methods; for another example, it is proposed to use "rotary kiln, fluidized furnace, fluidized furnace, shaft furnace, "Multi-hearth furnace" and other reactors actually cover almost all commonly used mainstream reactors in the field of metallurgical industry, but different reactors have very different requirements for raw materials. The shaft furnace can only handle "coarse" particles larger than 8mm. "Fine particles" require pelletizing and pre-sintering treatment, and boiling chlorination is generally suitable for processing fine particles, so for a specific vanadium raw material, it cannot be directly applied to rotary kilns, fluidized furnaces, fluidized fluidized furnaces, shaft furnaces, multi- Hearth furnace and other reactors; besides, "fluidized furnace" and "fluidized fluidized furnace" are essentially the same, but they are called differently; it can be seen that because the operation methods and conditions of these reactors are very different, only the principle process is given. (2) vanadium oxychloride is passed into ultrapure aqueous solution and hydrolyzed, because vanadium pentoxide is very easy to dissolve in hydrochloric acid solution, the precipitation recovery rate of vanadium is too low; When HCl concentration is greater than 6.0mol / L In the hydrochloric acid solution, when vanadium pentoxide dissolves, it will be reduced to VOCl 2 , release chlorine gas simultaneously, and this will further reduce the precipitation recovery rate of vanadium; Precipitation and washing process will certainly produce a large amount of vanadium-containing hydrochloric acid solution, be difficult to realize comprehensive treatment effectively; (3) vanadium oxychloride is directly passed into ammoniacal solution Ammonium salt precipitation is carried out in the precipitation washing process, and there is also a large amount of ammonia nitrogen wastewater generated during the precipitation washing process, which is difficult to deal with and easily causes environmental pollution.

The method described in these two patents is only applicable to V 2 o 3 It is not suitable for the preparation of low-valent vanadium oxides in other valence states, because the system does not have the structure and function to precisely control the reduction

[0008] In addition, for large-scale industrial applications, the existing chlorination technology for the preparation of high-purity and low-priced vanadium oxides still has the following three problems: (1) The chlorination of vanadium raw materials is a strong exothermic process, and the heat generated by the chlorination reaction In addition to satisfying the preheating of solid and gaseous reaction materials, there is still a large amount of surplus, which will cause local overheating of the vanadium material, affecting the fluidization state and the selectivity of chlorination. It is necessary to find an effective method to remove the heat from the fluidized bed; (2) The preparation of vanadium pentoxide by vanadium oxychloride still has no efficient preparation method that is conducive to large-scale operation

Vanadium oxychloride is directly passed into pure water or ammonia water process, the recovery rate is low, the environment pollution is big, and it is difficult to realize large-scale industrialization; (3) vanadium-containing ammonium salt and vanadium pentoxide lack mature precise control reduction technology

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