Kawasaki Steel Corporation

Nippon Sheet Glass Company, Limited

Research Development Corporation

Solex Research Corporation of Japan

Kawasaki Steel Corporation, Technical Research Division

Kazuhiro Uchino

Minoru Hoshino

Yoshio Nakazato

Toshio Watanabe

Yasuhiko Sakaguchi

Fukuo Aratani

Akira Yamamoto

Tetsuro Kawahara

Mitsugi Yoshiyagawa

Noboru Ishihara

Kanji I

Kunio Miyata

Masato Ishizaki

Method for producing high-purity metallic silicon and apparatus therefor

A metal stripping system and an operation process therefor which includes the following elements and steps. A main part of this system is a crystallization apparatus for metal stripping comprising a mixing zone of organic solvent and fluoride series stripping solution, a settling zone for organic solvent, a settling zone for stripping solution, a separation zone for fluorinated metal complex crystal and a stripping solution cooling zone. In the operation of the system wherein the organic solvent containing extracted metal ions is contacted with the fluoride series stripping solution to deposit the fluorinated metal complex crystal and then the crystal is recovered as metal or metal oxide, the stripping solution is circularly used by supplying NH.sub.4 HF.sub.2 solution to the cooling zone, supplying the stripping solution discharged from the apparatus and absorbed with a decomposition gas of the crystal to the mixing zone, and supplying a filtrate after the crystal separation to the settling zone for stripping solution.

Metal stripping system and an operation process therefor

A process for treating and recovering pickling waste liquids used for the pickling of stainless steel such as nitric-hydrofluoric acid, nitric acid, hydrochloric acid and, sulfuric acid is disclosed, which comprises recovering the nitric-hydrofluoric acid and the iron oxide or metallic ion from the waste liquids of nitric-hydrofluoric acid and nitric acid by two solvent extraction processes and recovering the Cr and Ni containing ferrite from the waste liquids of sulfuric acid or hydrochloric acid by a ferrite formation process. When the waste acid is sulfuric acid, gypsum of a high purity can be obtained.

Process for treating and recovering pickling waste liquids for stainless

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Chiba, Japan

Kazuhiro Uchino