Treatment of fluorine-containing wastewater from polysilicon production

Is this wastewater generated from acid pickling processes? Do you need to recover hydrofluoric acid? If its concentration is high and it has significant recovery value, feel free to contact me; I can send you some relevant information. wang*uhu007@163.com

Preliminary treatment can be carried out through limestone precipitation; for more advanced treatment, membrane filtration can be used, after which the water can be reused in production.

:):):) Please, friends upstairs, share your insights!

It seems there are specialized techniques for recycling waste acid now, but I’m not quite sure how it’s done!

Reply to 1# hanying1983: What is the purpose of seeking advanced technologies for wastewater treatment? Is it still the case that this treatment method is used to deal with emissions that do not meet the standards? The design solution needs to be determined based on your requirements along with the actual circumstances

I’m not aware of the specific components and concentrations in your wastewater. I have technologies for treating fluoride-containing wastewater; feel free to contact me. Email: yyqch@126.com

The fluorine-containing wastewater mentioned by the poster, if it refers to the etching acid waste liquid used in polysilicon post-treatment (a mixture of 49% hydrofluoric acid and 70% nitric acid), it seems that new filtration devices have now been developed that can remove the solid particles from this liquid, allowing the acid to be recycled. If it refers to the wastewater containing trace amounts of fluorine that is generated after acid treatment followed by rinsing the surface with ultrapure water, the current approach is generally to add lime slurry to form calcium fluoride precipitates, which are then settled. The fluoride ion concentration can apparently meet the third-level discharge standard of 20 mg/l specified in the national standard G-8978-1996. If the water is to be reused, membrane filtration using wastewater reutilization systems is required, but the cost is too high; it seems that many companies in China have installed such systems yet have not put them into use.

It generally needs to be below 10 mg/L! If reused, it is also relatively simple; the fluidized bed crystallization technique can be used to meet the standards in just one step!

The wastewater containing trace amounts of fluorine that results from rinsing the surface with ultrapure water after acid treatment is treated by adding lime slurry to form calcium fluoride precipitates, followed by sedimentation; thereafter, PAC and PAM are used for coagulation. However, it is difficult to keep the fluoride ion concentration below the allowable level of 10 mg/l. Based on information from professional water treatment books, we are making efforts in this regard. The effect is good.