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

Abstract

The invention belongs to the fields of metallurgy and chemical industry, and specifically discloses a system and a method for preparing a high-purity and low-valence vanadium oxide through an efficient clean chlorination method, wherein the high-purity and low-valence vanadium oxide powder is prepared by using a process comprising chlorination, dust removal leaching, purification, catalytic oxidation and fluidization reduction, and the equivalent average valence of vanadium can be any one value selected from 3.0-4.5. According to the present invention, the chlorine gas is regenerated by introducing clean oxygen-rich air into the catalytic oxidation fluidized bed, such that the chlorine gas circulation is achieved, and the production cost is reduced; the hydrogen chloride in the catalytic oxidation tail gas is recovered by the hydrochloric acid condensation absorption tower, such that the generation of vanadium-containing hydrochloric acid is eliminated, and the environmental protectioncost is substantially reduced; and the system and the method have advantages of strong raw material adaptability, chlorine gas regeneration cycle, no vanadium-containing hydrochloric acid production,no emission of polluting wastewater, low production energy consumption, stable product quality and the like, are suitable for the large-scale industrial production of high-purity and low-valence vanadium oxide with the purity of more than 4N, and have good economic and social benefits.

Description

technical field [0001] The invention belongs to the field of metallurgy and chemical industry, and in particular relates to a system and method for preparing high-purity and low-priced vanadium oxides by an efficient and clean chlorination method. Background technique [0002] Low-valent vanadium oxides include vanadium trioxide, vanadium tetroxide and their mixtures. They 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 hard alloys. Additives etc. With the continuous development of new energy technologies, the battery industry has increasingly strong demand for high-purity and low-priced vanadium oxides (purity above 3N5), including all-vanadium redox flow batteries (VRB) with good large-scale energy storage performance and electric vehicles. Vanadate-based lithium-ion batteries, etc. [0003] In recent years, the technology of preparing high-...

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Problems solved by technology

This patent has the following deficiencies: (1) carbon chlorination is a violent exothermic process, which needs to transfer heat to the outside of the chlorination furnace; air is blown into the chlorination furnace in this patent, which will cause the furnace temperature to rise and affect Fluidized state; (2) The flue gas dedusting-condensation part is very simple, and the chlorinated flue gas is mixed with a large amount of unreacted dust. A single cyclone separator cannot achieve effective dust removal effect, and the backward movement of dust will block the follow-up pipe Road, bring the hidden danger of stopping production; Simultaneously insufficient vanadium oxychloride condensation will reduce recovery rate greatly, increase production cost; (3) rectifying purification can only separate the metal chloride that differs greatly from the saturated vapor pressure of vanadyl trichloride However, some such as titanium, silicon chloride and vanadyl chloride saturated vapor pressure are close, and it is difficult to obtain high-purity vanadyl chloride by the method of rectification alone; (4) gas phase ammonization-ammonium salt calcination process will produce a large amount of chlorine Ammonium chloride and ammonia-rich tail gas increase environmental protection costs

This patent has the following deficiencies: (1) There are a large amount of impurities such as iron, manganese, chromium, titanium, and aluminum in the vanadium slag, which are converted into chlorides in a large amount during the chlorination process, and a large amount of chlorination tailings pollute the environment and cannot be used economically and efficiently; (2) This patented technology also has the problems of overheating of the chlorination furnace, blockage of pipelines, low recovery rate of vanadyl trichloride, substandard purity of vanadyl trichloride, and inability to handle a large amount of vanadium-containing hydrochloric acid

[0008] Chinese patent application CN106257724A discloses the technology of using fluidized bed to reduce ammonium vanadate to prepare high-purity and low-priced vanadium oxides. The main problem is that the reduction tail gas contains a large amount of ammonia and ammonium chloride dust, which seriously pollutes the environment and increases environmental protection. cost, it is difficult for large-scale industrial production; and the latent heat of the reduction tail gas is not utilized, which is not conducive to the reduction of production costs

Chinese patent application CN106257725A discloses a technology for preparing high-purity and low-valent vanadium oxides by reducing vanadium-containing materials in a fluidized bed. The disadvantage is that the latent heat of the tail gas is not utilized, and the production cost is increased.

Chinese patent application CN106257726A discloses a technology for preparing high-purity low-valent vanadium oxides by reducing ammonium vanadate in a fluidized bed. The disadvantages are the pollution of ammonia in the reduction tail gas and the utilization of latent heat of the reduction tail gas.

Chinese patent application CN106257727A discloses a technology for preparing high-purity vanadium oxide by reducing vanadium pentoxide wet material in a fluidized bed. The main deficiency of this patent is that the water content of vanadium pentoxide filter cake is relatively high, which is not conducive to screw feeding Moreover, the vanadium pentoxide wet material is directly subject to the high-temperature gas heat exchange from the tail gas burner, which is prone to sintering, which leads to a wide particle size distribution of the vanadium pentoxide powder, which is not conducive to the reduction of the reducing fluidized bed. operate

CN106257728A also discloses a technique for preparing high-purity and low-valence vanadium oxides by reducing vanadium pentoxide powder in a fluidized bed, which also has the problem that the latent heat of the reduction tail gas is not utilized

[0009] In addition, for large-scale industrial applications, the existing chlorination technology for preparing high-purity and low-priced vanadium oxides still has the following five 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 dedusting and condensation section of chlorinated flue gas is related to the continuity of production and the recovery rate of vanadium trichloride, which requires special devices to be strengthened; (3) rectification / distillation purification can only be separated from the saturated vapor pressure of vanadyl trichloride There are large differences in metal chlorides, but some such as titanium and silicon chlorides have similar saturated vapor pressures to vanadyl chloride. It is difficult to obtain high-purity vanadyl chloride by rectification / distillation alone, and other effective impurity removal methods are required. (4) There is still no clean, efficient and environmentally friendly preparation method for preparing vanadium pentoxide by vanadium oxychloride. If chlorine cannot be recycled, vanadium-containing hydrochloric acid cannot be effectively processed, which will greatly increase production costs and enhance environmental protection costs. It is difficult to achieve large-scale Industrialization; (5) Preparation of low-priced vanadium oxides by fluidized bed reduction still faces problems such as material transportation, treatment of ammonia in tail gas and comprehensive utilization of heat in tail gas

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