What Is Fluoride Treatment?
Fluoride treatment [1] refers to technologies that use fluoride, such as hydrogen fluoride (HF) and silicon tetrafluoride (SiF4), to be recycled or harmlessly treated by methods such as absorption and adsorption.
- Fluoride treatment refers to technologies that use fluoride, such as hydrogen fluoride, silicon tetrafluoride, etc., to be recycled or harmlessly treated by means of absorption and adsorption [2]
- The wet purification process is divided into limestone / lime method, sodium-alkali method, ammonia method, metal oxide method, double-alkali method, etc. Among them, sodium-alkali method and double-alkali method are more commonly used, and more than 90% of domestic enterprises adopt this method [3]
- The ground smoke purification system is to collect high-concentration hydrogen fluoride flue gas, remove dust therefrom, and absorb hydrogen fluoride in water or sodium hydroxide solution in an absorption tower. If sodium hydroxide solution is used as the absorption liquid, sodium metaaluminate (NaAlO 2 ) is added to the absorption liquid to recover the cryolite (Na3AlF 6 ). If water is used as the absorbing solution, adding aluminum oxide (Al 2 O 3 ) into it can recover aluminum fluoride, and adding alkali can also recover cryolite. Cryolite is an indispensable raw material for aluminum smelting. The purification efficiency of the ground smoke exhaust purification system can reach 90 ~ 95%.
- The device of the skylight smoke exhaust purification system is usually installed on the roof of the workshop. In order to reduce the smoke exhaust resistance, a jet scrubber and a demister are installed directly after the smoke exhaust machine. The purification efficiency of the skylight smoke purification system is about 70 to 90%. The efficiency is related to the structure, installation method, atomization condition and liquid-gas ratio of the spray scrubber used. Pay attention to the corrosivity of the solution when recovering fluoride by wet method, and choose the material of the recovery device correctly.
- It is mainly chemically adsorbed with solid alumina to produce aluminum fluoride. Dry purification is mostly used for the purification of smoke on the ground of electrolytic aluminum. The efficiency of fluoride removal by dry adsorption device can reach more than 98% [1] .