Process and equipment for recycling nitrogen trifluoride electrolytic residue resources

Abstract

The invention discloses a nitrogen trifluoride electrolytic residue resource recovery process and equipment, and the process comprises the following steps: crushing electrolytic residues, carrying out high-temperature anaerobic pyrolysis, retaining metal fluoride in a powder form, gasifying most of ammonium bifluoride and hydrogen fluoride into steam, introducing the pyrolyzed steam into a condensing device, and condensing the condensed steam to obtain the nitrogen trifluoride electrolytic residue resource. The condensate after condensation is ammonium bifluoride, the non-condensable gas is hydrogen fluoride, crystallizing the condensate, and recovering to obtain an ammonium bifluoride solid; introducing the hydrogen fluoride noncondensable gas into a container filled with calcium oxide for reaction to generate calcium fluoride; metal fluoride residues obtained after pyrolysis are completely defluorinated through high-temperature steam, the defluorinated steam is absorbed by ammonia water, and metal oxide powder obtained after defluorination is cooled and then recycled. Separation and clean production of ammonium bifluoride, hydrogen fluoride and metal oxides in the nitrogen trifluoride electrolytic residues are realized by utilizing phase change characteristics of gas, solid and liquid of ammonium bifluoride, hydrogen fluoride and metal fluoride at different temperatures and combining with equipment, and resources are recycled.

Description

technical field [0001] The invention relates to the technical field of recycling nitrogen trifluoride electrolysis residues, in particular to a process and equipment for recycling nitrogen trifluoride electrolysis residue resources. Background technique [0002] As an excellent plasma etching gas in the microelectronics industry, high-purity nitrogen trifluoride gas has excellent etching rate and selectivity for silicon and silicon oxide, so it occupies an important position in many industries such as integrated circuits and chip manufacturing. In the industry, there are two production methods of nitrogen trifluoride: one is the electrolysis of anhydrous hydrogen fluoride to generate fluorine gas, which is then reacted with molten ammonium bifluoride to generate nitrogen trifluoride; the other is the electrolysis of anhydrous hydrogen fluoride and molten ammonium bifluoride. The mixture can generate nitrogen trifluoride directly in the electrolytic cell. The nitrogen triflu...

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Problems solved by technology

The treatment methods for the electrolytic waste residue of nitrogen trifluoride mainly include the following methods: one is to carry out lime neutralization and precipitation on the fluoride ions in the nickel-containing waste residue, and then use a chemical method to treat the ammonium ion with ammonia nitrogen. The method is only to carry out harmless treatment, without realizing the recycling of resources, resulting in waste of resources, and will increase the cost of treatment; the other is to dissolve the electrolytic nickel-containing waste residue in water, and then separate the solid and liquid to make the liquid become Ammonium fluoride aqueous solution, the solid becomes nickel-containing waste residue, and the solid residue needs to be further separated. This treatment method is relatively complicated, and the separated nickel-containing waste residue is hazardous waste, which still needs to be handled by a professional company.

Another method is to use hydrofluoric acid to dissolve nickel slag, add sulfuric acid to the electrolyte, and use electrolysis to recover nickel metal. This treatment method consumes a lot of energy, and after adding sulfuric acid, other impurities will be introduced, resulting in subsequent treatment processes and cost increase

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