Method for recycling waste gas generated by rare earth electrolyzed by fluoride system

Abstract

The invention discloses a method for recycling waste gas generated by rare earth electrolyzed by a fluoride system. The method includes the steps: treating the waste gas generated by electrolysis by adust removal device, leading in lithium hydrogen carbonate serving as absorbing agents to perform chemical absorption on a spray absorption tower, directly leading the chemically absorbed waste gas with carbon dioxide serving as a main component in a lithium carbonate liquid tank, converting lithium carbonate into the lithium hydrogen carbonate with high solubility, injecting the lithium hydrogencarbonate into the spray absorption tower to be recycled, and continuing to capture fluorine ions in fluorine-containing gas; performing solid-liquid separation, washing, drying and high-temperaturedehydration on a new substance generated after spraying absorption to obtain lithium fluoride for electrolyzing rare earth. According to the method, rare earth dust and fluorine-containing tail gas are firstly separated, the lithium hydrogen carbonate serves as a capturing agent of the fluorine ions, the comprehensive yield can reach 84.50% or more, the comprehensive yield of a system reaches 96%or more after reaction is completely balanced, carbon dioxide in the absorbed waste gas serves as a raw material to be directly led into the lithium carbonate liquid tank to circularly prepare a lithium hydrogen carbonate absorbing agent, and emission of the carbon dioxide is greatly reduced.

Description

technical field [0001] The invention relates to a method for recycling rare earth waste gas from electrolysis of a fluoride system, and belongs to the fields of environmental protection and resource recycling. Background technique [0002] During the smelting process of rare earth metals, the main components of waste gas are carbon dioxide and a small amount of fluorine-containing gas. At present, my country's rare earth metal smelting enterprises mainly use two methods for treating waste gas: dry method and wet method. [0003] The dry treatment process is as follows: the waste gas generated in the rare earth metal smelting process is first captured and collected, and then the rare earth dust in the waste gas is removed through gravity sedimentation, cyclone dust removal, bag dust removal, etc., and then calcium oxide or calcium hydroxide is used with the fluorine in the waste gas Ion reaction produces calcium fluoride, realizes dust removal and fluorine removal, and meets...

AI Technical Summary

Problems solved by technology

The rare earth dust obtained by this process contains a certain amount of sodium fluoride, which cannot be used directly, and the process of processing the dust to oxidize rare earth is complicated, which increases the environmental protection pressure of the waste gas treatment process; at the same time, because sodium fluoride is easy to crystallize, it is easy to cause the spray tower Blockage, equipment maintenance is difficult, and the generated sodium fluoride may cause secondary pollution. It needs to be treated with calcium oxide or calcium hydroxide for secondary treatment. The process is complicated and the efficiency is low.

[0005] To sum up, both the dry treatment process and the wet treatment process of rare earth metal smelting waste gas use alkaline substances to defluorinate. Although they can eventually generate harmless substances, the fluoride produced has little utilization value. caused a waste of fluorine resources

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