Method for producing vanadium trioxide by adopting fluidized bed reactor

Abstract

The invention relates to a method for producing vanadium trioxide by adopting a fluidized bed reactor, belonging to the field of the chemical industry and metallurgy. Heat is provided for reaction by a mode of preheating the materials containing vanadium to be 400-550 DEG C, the materials containing vanadium are preheated by adopting a two-stage cyclonic preheater, and high-temperature smoke generated by a combustion chamber provides heat. Gas with heat value of being larger than 1250kcal / Nm<3> is adopted to be reduced for 5-20 minutes at the temperature of 700-850 DEG C, and a vanadium trioxide product with vanadium grade of being more than 66% can be obtained. The method has the advantages of high reduction efficiency, good energy utilization and suitability for large-scale production of vanadium trioxide.

Description

technical field [0001] The invention belongs to the technical fields of chemical industry and metallurgy, and in particular relates to a method for producing vanadium trioxide by using a fluidized bed reactor. Background technique [0002] Vanadium trioxide is an important vanadium compound, which has important applications in metallurgy, electronics, chemical industry and other fields. In industry, vanadium trioxide is generally produced by reducing ammonium vanadate or vanadium pentoxide. For example, the reaction equation for producing vanadium trioxide as raw material with ammonium metavanadate is as shown in (1): [0003] 2NH 4 VO 3 +2H 2 =2NH 3 +V 2 o 3 +3H 2 O (1) [0004] The reduction reaction itself is relatively simple. One of the difficulties in implementing the reaction on an industrial scale is how to supply heat for the process, because the reduction reaction is usually carried out at a high temperature of 800-900 ° C, which is a strong endothermic pro...

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Problems solved by technology

Although the use of rotary kiln to reduce ammonium vanadate to produce vanadium trioxide has been verified by industrial production for many years, and the technology is relatively mature, there are still the following problems: (1) The contact efficiency between reducing gas and ammonium vanadate is low, resulting in low reduction reaction efficiency , the reaction time is long, even at a high temperature of 850 ° C, it takes more than 1 hour of reaction time; (2) the product vanadium grade is low: the vanadium grade of the vanadium trioxide product obtained by reduction in a rotary kiln is about 64%, which is difficult to obtain High-grade vanadium trioxide products; (3) High-temperature dynamic sealing is difficult, and it is difficult to completely avoid the leakage of reducing gas to the environment: At present, the production of ammonium vanadate in rotary kilns is carried out in fully ventilated workshops at home and abroad to ensure Safety; (4) Low operating rate: Since the rotating kiln body is directly heated to a high temperature of about 900°C by flame, the kiln body is easily broken or even burned through, resulting in a high accident rate

However, the method disclosed in this patent is only suitable for laboratory and small-scale production, and cannot adapt to the requirements of large-scale industrial production, mainly because the method has the following deficiencies: (1) cannot provide enough heat exchange area during large-scale production: using this When heat is supplied by the patented method, the heat exchange area has a linear relationship with the diameter of the fluidized bed, while the processing capacity (heat required for reaction) has a quadratic relationship with the diameter of the fluidized bed. It can be predicted that with the increase of the diameter of the fluidized bed, The heat transfer area will be increasingly unable to meet the needs of the reduction reaction; (2) the cost of electric heating is high; (3) there is only a reduction unit, no vanadium trioxide cooling system: because vanadium trioxide will Oxidation produces vanadium tetroxide or vanadium pentoxide, which will oxidize rapidly when it is higher than 300 ° C. Therefore, in industrial production, it is still necessary to provide methods and equipment that can realize cooling of a large amount of vanadium trioxide under air-isolated conditions

Although the process and equipment provide a production technology to replace the existing rotary kiln to produce vanadium trioxide on an industrial scale, and can obtain higher-grade vanadium trioxide products, the process also has low energy utilization The problems are mainly manifested in: (1) The reducing gas in the outlet gas of the fluidized bed reactor is not utilized: the actual production data shows that when coke oven gas is used to reduce ammonium vanadate, the utilization rate of coke oven gas is between 60-70 %, the process treats the tail gas at the outlet of the fluidized bed reactor by direct ignition and then evacuation, wasting 30-40% of the energy of unreacted coke oven gas; (2) the heat supply efficiency of the built-in heat exchange tube method Low: On the one hand, this is due to the large heat transfer resistance and low efficiency of the built-in heat exchange tube compared with direct heat exchange. On the other hand, because the reaction is carried out at a high temperature of 600-800 ° C, the temperature of the flue gas discharged from the heat exchange tube At least at 650-850°C, only 20-40% of the heat of the high-temperature flue gas is utilized, and more than 60% of the heat is discharged into the atmosphere with the flue gas, causing a lot of energy waste

This shows that existing fluidized bed reactor produces vanadium trioxide technology, or is not suitable for large-scale production, or energy utilization efficiency is low, therefore, still need to develop more efficient fluidized bed reactor to produce vanadium trioxide Vanadium Technology

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