METHOD FOR PROCESSING WASTE WATER CONTAINING FLUORINE AND SILICON, METHOD FOR PRODUCING CALCIUM FLUORIDE, AND FACILITY FOR PROCESSING FLUORINE-CONTAINING WASTE WATER

摘要

An object (first object) of the invention is to provide a waste water treatment technology (pretreatment technology in particular) which makes it possible to recover fluorine at a high recovery rate as highly pure calcium fluoride, without diluting waste water containing fluorine and silicon, i.e. to recover fluorine from high-concentration waste water containing fluorine and silicon. Waste water containing fluorine and silicon is supplied to a pH controlling tank 1 and sodium hydroxide (NaOH) is added thereto, with the result that sodium silicate is precipitated. Thereafter, the waste water is supplied to a solid-liquid separator 2 so that solid-liquid separation of sodium silicate is conducted.