METHOD OF TREATING WASTE WATERS TO REMOVE FLUORINE Russian patent published in 2004 - IPC

FIELD: waste water treatment. SUBSTANCE: invention relates to sorption-precipitation methods for removing fluorine from waste waters and can be applied in mining, metallurgy, chemical and other industries. Waste water is treated with water-soluble sulfate compound of titanium in the form of titanyl sulfate monohydrate, which is taken in amount corresponding to at least 5 mole titanium per 1 gion of fluorine present in waste water to be treated, while containing pH of resulting pulp within a range of 3.0-5.5, preferably 3.5-5.0, and separated fluorine-saturated solid phase is treated with 55.0-93.5% sulfuric acid at 120-130 C to give hydrogen fluoride and regenerated titanium sulfate compound. If original waste water contains elevated (more than 12.5 mg/l) amount of fluorine, it undergoes pretreatment with calcium hydroxide in amount at least 1.5 mg calcium oxide per 1 mg fluorine and sulfuric acid treatment is carried out with 75.0-93.5% sulfuric acid at 170-180 C, after which formed cake is leached with water to give solution of regenerated titanium sulfate compound and calcium sulfate precipitate. Proposed method allows for isolation of fluorine in the form of commercial compound. E.g. sodium fluoride or hydrofluoric acid and regeneration of sorbent up to 98.5% (according to titanium). Residual level of fluorine and sulfate ion does not exceed maximum permissible concentration for fish-breeding- and drinking-destination reservoirs, while secondary contamination with titanium compounds is not observed. EFFECT: enhanced waste water treatment efficiency. 7 cl, 6 ex