Method for preparing rare earth polishing powder and recovering ammonium salt by using fluorine-containing niobium-tantalum wastewater

Abstract

The invention relates to a method for preparing rare earth polishing powder and recovering an ammonium salt by using fluorine-containing niobium-tantalum wastewater, wherein the fluorine-containing wastewater is the filtrate obtained by using ammonia water to precipitate tantalum or niobium and mainly contains ammonium fluoride and ammonium sulfate. According to the method, excessive soluble salts of rare earth lanthanum and cerium are added to the wastewater and comprise one or a combination comprising a plurality of materials selected from a sulfate, a chloride, an acetate and a nitrate so as to make the fluorine be completely precipitated, ammonium bicarbonate is added to precipitate the excessive rare earth, filtration is performed to obtain the precipitates such as the rare earth carbonate and the fluorine carbonate, drying, calcination, and crushing grading are performed to obtain the qualified rare earth polishing powder, and the filtrate is subjected to concentration crystallization and centrifugal separation to obtain the corresponding ammonium salt, wherein the ammonium salt can be used as the mine leaching agent of the ion adsorption type rare earth. According to the present invention, the environmental pollution problem of the fluorine and the ammonium in the niobium-tantalum production wastewater is solved while the two products such as the fluorine-containing rare earth polishing powder and the rare earth mine leaching agent are developed, such that the double purposes of the higher value application of the substance and the environmental protection are achieved, and the important significance is provided for the application of the niobium-tantalum production and the rare earth and the development of the environmental protection industry.

Description

technical field [0001] The invention belongs to the fields of environmental protection, hydrometallurgy and new material processing, and specifically relates to a method for producing rare earth polishing powder by using fluorine-containing waste water in the production of niobium and tantalum and by-producing mixed salt with ammonium sulfate as the main component. Background technique [0002] Tantalum and niobium are essential metal raw materials in new materials. Niobium oxide, for example, is widely used in high-tech fields such as catalysis, ceramic capacitors, piezoelectric ceramics, new heat-sensitive materials, dielectric materials, magnetic materials, and optical materials due to its unique properties. [0003] In the production process of tantalum-niobium hydrometallurgy, niobium elements are produced and sold as niobium oxide products, while tantalum elements are mainly sold as potassium fluorotantalate products and a small amount of tantalum oxide products. In t...

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Problems solved by technology

[0004] This waste water cannot be discharged directly, and fluorine resource is a scarce resource in our country, and it is a national plan quota export product; therefore, recycling fluorine in waste water has economic and social benefits; in the current recovery method, the recovered fluorine through the concentration process It is a binary ammonium salt (a mixture of ammonium fluoride and ammonium sulfate). It needs to be sublimated by heating (about 340°C) to separate ammonium bifluoride and ammonium sulfate. The recovery process is very complicated, the equipment investment is large, and the energy cost is relatively high. high

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