The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 07, 1977
Filed:
Mar. 01, 1976
Shigeoki Nishimura, Hitachi, JA;
Toshio Sawa, Hitachi, JA;
Kouji Otani, Hitachi, JA;
Seiichi Kikkawa, Katsuta, JA;
Hitachi, Ltd., Tokyo, JA;
Abstract
There are disclosed methods for removing fluorine values from fluorine-containing waste waters, in which aluminum ions are added to fluorine-containing waste water to convert fluorine to hydroxyfluoride complexes, adding phosphoric acid or phosphate and calcium compound are added to form fluoride apatite with residual fluorine in the waste water, and the hydroxy-fluoride complex and fluoride apatite are removed from the waste water. When waste water containing a phosphate in addition to fluorine is treated, the waste water is divided, according to the fluorine concentration, into concentrated waste water having a high fluorine concentration and dilute waste water having a low fluorine concentration; calcium compound is added to the concentrated waste water to form calcium fluoride, aluminum ions are added to the dilute waste water to form a hydroxy-fluoride complex; the so treated dilute waste water is mixed with the phosphate-containing concentrated waste water from which the precipitated calcium fluoride has been removed, calcium compound is added to the mixture to form fluoride apatite, and the hydroxy-fluoride complex and fluoride apatite are removed from the mixed waste water.