Kurita Water Industries Ltd.

Hitachi Plant Engineering Construction Co., Ltd.

Yoshihiro Eto

Hiroyuki Harada

Nobuhiro Miki

Matagoro Maeno

Toshiro Fukutome

Norio Terasawa

Masahiro Sakata

Tadahiro Ohmi

Fluorine is recovered as calcium fluoride from a fluoroetchant solution composed mainly of hydrogen fluoride and ammonium fluoride using a sealed reaction tank equipped with a supply port for adding the fluoroetchant solution to the tank, a supply port for adding calcium carbonate to the tank, a vapor supply port for adding steam to heat the solution in the tank, an air supply port for providing air to aerate the contents of the tank, a stirrer for stirring the contents of the tank, an ejector for removing vapors from the tank connected to the tank via a mist separator for separating mist from the vapors being removed from the tank, and an exhaust port for removing calcium fluoride from the tank.

Apparatus for recovering calcium fluoride from fluoroetchant

Calcium fluoride with high purity of very small content of unreacted calcium carbonate and silica is recovered from an etchant mainly composed of hydrogen fluoride or hydrogen fluoride and ammonium fluoride. The etchant is reacted with calcium carbonate with transfer directions of the etchant and calcium carbonate being controlled within a composition region in which mole equivalent ratio of ammonium fluoride/hydrogen fluoride is specified.

Method for recovering calcium fluoride from fluoroetchant

Growing community of inventors

Kanagawa, Japan

Yoshihiro Eto