Treatment method of fluorine-containing nickel slag generated in nitrogen trifluoride preparation process

Abstract

The invention relates to a treatment method of fluorine-containing nickel slag generated in a nitrogen trifluoride preparation process, and belongs to the technical field of harmless treatment of nickel-containing hazardous wastes. The method comprises the following steps: (1) crushing the fluorine-containing nickel slag into solid powder; (2) dissolving the fluorine-containing nickel slag solid powder by using a hydrofluoric acid solution, performing stirring at 30-60 DEG C, and adding an oxidizing substance in the stirring dissolution process until the fluorine-containing nickel slag is completely dissolved to obtain a mixed solution a; (3) adjusting the pH value of the mixed solution a to 3.5-4.5 by using ammonia water, and performing filtering to obtain ferric hydroxide precipitate and a mixed solution b; and (4) continuing to adjust the pH value of the mixed solution b to 6.5-7.5 with the ammonia water, performing filtering to obtain nickel fluoride and a mixed solution c, heating and concentrating the mixed solution c, and performing cooling crystallizing to obtain ammonium fluoride and a mixed solution d. The method realizes recovery and cyclic utilization of nickel metal resources and ammonium fluoride, and can significantly reduce the production cost of nitrogen trifluoride.

Description

technical field [0001] The invention relates to a treatment method for fluorine-containing nickel slag generated during the preparation of nitrogen trifluoride, and belongs to the technical field of harmless treatment of nickel-containing hazardous waste. Background technique [0002] High-purity nitrogen trifluoride gas (purity above 4.5N) is an excellent plasma etching gas in the microelectronics industry, and occupies an important position in many industries such as integrated circuits and chip manufacturing. At present, the preparation method of nitrogen trifluoride is mainly electrolytic method. In the process of preparing high-purity nitrogen trifluoride by electrolysis, the anode nickel plate will gradually lose electrons and dissolve, and nickel will be deposited on the bottom of the electrolytic cell in the form of nickel fluoride, etc., and some hydrogen fluoride, ammonium fluoride, and equipment will be entrained during the deposition. The iron element in the ele...

AI Technical Summary

Problems solved by technology

At present, there are mainly the following methods for the treatment of nickel-containing waste slag wastewater in the electrolytic production process of high-purity nitrogen trifluoride: one is to carry out lime neutralization and precipitation on the fluoride ions in nickel-containing waste slag, and then use ammonium ion Ammonia nitrogen treatment is carried out by chemical method. This treatment method is only for harmless treatment and does not realize the recycling of resources, resulting in a waste of resources and an increase in treatment costs; the other is to dissolve the electrolytic nickel-containing waste residue with water , and then solid-liquid separation, so that the liquid becomes an ammonium fluoride aqueous solution, and the solid becomes nickel-containing waste residue, and the solid residue needs to be further separated. company processing

Another method is to add sulfuric acid to the electrolyte after hydrofluoric acid dissolves the nickel slag, and use electrolysis to recover nickel metal. This treatment method consumes a lot of energy. In addition, adding sulfuric acid introduces new impurities, and subsequent processing is troublesome.