Recycling method for fluorine-containing ammonia-nitrogen-containing wastewater through tantalum-niobium wet-process smelting

Abstract

The invention discloses a recycling method for fluorine-containing ammonia-nitrogen-containing wastewater through tantalum-niobium wet-process smelting, and relates to the technical field of wastewater recycling. The recycling method comprises the following steps: adding hydrofluoric acid or sulfuric acid into wastewater to regulate the pH value of the wastewater to 5-6, completely converting freeNH3 in the wastewater into NH<4+> for being dissolved into the wastewater, performing primary screening on mixed salt wastewater into an ammonium fluoride solution and an ammonium sulfate solution through a primary nanofiltration membrane system, pumping the primarily separated ammonium fluoride solution into a secondary nanofiltration membrane system, removing a little ammonium sulfate in the ammonium fluoride solution, wherein a little ammonium fluoride is contained in the primarily separated ammonium sulfate solution; arranging a fluorine ion concentration online monitor in the primary nanofiltration membrane circulating system until concentration of fluorine ions is lower than a set value; automatically opening an electric regulating valve for discharging the ammonium sulfate solutionwith purity reaching design requirements out of the primary nanofiltration membrane system; and introducing the concentrated ammonium fluoride solution and the concentrated ammonium sulfate solutioninto a low-temperature membrane evaporation and crystallization system, thereby recycling ammonium fluoride crystals and ammonium sulfate crystals.

Description

technical field [0001] The invention relates to the technical field of waste water treatment and recovery, in particular to a recovery and treatment method for waste water containing fluorine and ammonia nitrogen in tantalum and niobium hydrometallurgy. Background technique [0002] In the hydrometallurgy process of tantalum and niobium, the waste water containing fluorine and ammonia nitrogen is the main waste water, accounting for about 80-90% of the total waste water; the main components of this part of waste water are ammonium sulfate, ammonium fluoride and free ammonia, and its pH is 9~10, the fluorine content is 5~10g / L, and the ammonia nitrogen content is 10~20g / L; in the national standard ("Sewage Comprehensive Discharge Standard" GB8978-1996), the ammonia nitrogen content of level 1 sewage is allowed to be less than 15mg / L, 2 The first-level discharge standard is less than 50mg / L; the fluorine content in the first and second-level discharge standards is 10mg / L, and ...

AI Technical Summary

Problems solved by technology

This treatment method will generate a large amount of neutralized slag, which requires a large amount of space to be stacked, with high water content, and a large amount of solids will cause secondary pollution, which has become a bottleneck for the development and production of enterprises.

[0004] For high-concentration ammonia-nitrogen wastewater, there are currently many methods such as stripping, steam stripping, membrane separation, etc., but the input cost is high, and the recovered low-concentration ammonia and ammonium salts cannot be directly reused, or fluoride is generated. Ammonia or ammonium sulphate, must be reprocessed

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