Selection of hydrofluoric acid removal equipment in acidic solutions
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There are two liquids, A and B. Solution A contains 5% sulfuric acid, 5000–10000 mg/L of chloride ions, 3000–6000 mg/L of fluoride ions, 900–1500 mg/L of nitric acid, and 0.2–0.5% hydrogen peroxide. Solution B contains 15–20% sulfuric acid, 1000–3000 mg/L of chloride ions, 500–1000 mg/L of fluoride ions, 500 mg/L of nitric acid, and 0.2–0.5% hydrogen peroxide. Now, it is intended to use concentration evaporation to concentrate fluoride, chloride, and nitric acid in the evaporated condensate, thereby removing these substances. I have a few questions for the experts here: First, is it feasible to use the evaporation and concentration of liquids A and B to remove fluoride, chlorine, and nitrate? Secondly, the water vapor generated during the evaporation and concentration process contains acids, fluorine, chlorine, etc., which cause significant corrosion to equipment. Are there any devices suitable for such working environments? Could you recommend any? Third, apart from concentration evaporation, are there any processes for removing fluoride, chlorine, and nitrate from liquids with low acidity and high impurities, without altering the properties of the original liquid? Thank you!
I have some bad news for you: it’s basically impossible to meet your requirement using the evaporation process. When these substances are mixed together, as the temperature rises to a certain level, almost all of the acids evaporate, though at different rates. If precise distillation is used, the costs related to materials, equipment, and operations might be too much for you to bear. This must be waste acid from metal surface treatment; it’s a challenge in this industry.
It’s not metal treatment, but the acid resulting from flue gas desulfurization using hydrogen peroxide. I remember that for fluoride removal using sulfuric acid, the temperature and acidity are controlled through evaporation, so that the acid remains while the fluoride evaporates.
It can be handled. During the evaporation and concentration process, attention should be paid to temperature and vacuum conditions; the material used for the equipment is ECTFE composed of graphite impregnated with tetrafluoroethylene dispersant and reinforced with steel. Operating costs can be controlled through multi-effect evaporation concentration, but the investment is relatively high. Since both nitric acid and hydrogen peroxide are strong oxidizers, high requirements are placed on corrosion prevention. If you are interested in technical exchanges, you can add me on WeChat: cztt001.