Patents by Inventor Suekazu Hirata

Suekazu Hirata has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Process for preparing hydrogen fluoride
    Patent number: 5219551
    Abstract: A process for preparing hydrogen fluoride, which comprises (i) reacting calcium fluoride with sulfuric acid to produce a gypsum and a gas containing hydrogen fluoride, (ii) separating hydrogen fluoride from said gas containing hydrogen fluoride, (iii) absorbing said hydrogen fluoride-separated gas with water to obtain an aqueous solution containing hydrogen fluoride and silicofluoric acid, (iv) reacting calcium carbonate with said aqueous solution to obtain a suspension containing silicic acid and calcium fluoride, (v) adding an alkaline substance to said suspension to make pH at least 8, thereby stabilizing the silicic acid as a colloidal solution, (vi) separating a calcium fluoride solid and the colloidal solution of silicic acid from said suspension, and (vii) recycling the separated calcium fluoride as a starting calcium fluoride.
    Type: Grant
    Filed: May 30, 1991
    Date of Patent: June 15, 1993
    Assignee: Asahi Glass Company Ltd.
    Inventors: Kunihiko Terase, Sadao Hagita, Kouichi Yokoyama, Yasuhiro Sanada, Michiomi Nagase, Suekazu Hirata
  • Process for producing anhydrous sodium carbonate crystal
    Patent number: 4406869
    Abstract: An anhydrous sodium carbonate crystal is produced by crystallizing a sodium carbonate hydrate crystal from an aqueous solution of sodium carbonate in a sodium carbonate hydrate crystallizing zone and transforming said sodium carbonate hydrate to an anhydrous sodium carbonate crystal in the presence of a crystal habit modifier in an anhydrous sodium carbonate crystallizing zone and recycling a separated mother liquor into said sodium carbonate hydrate crystallizing zone.
    Type: Grant
    Filed: January 19, 1981
    Date of Patent: September 27, 1983
    Assignee: Asahi Glass Company Ltd.
    Inventors: Keiichi Nakaya, Kohji Kawanami, Suekazu Hirata
  • Process for producing anhydrous sodium carbonate crystal
    Patent number: 4405592
    Abstract: An anhydrous sodium carbonate crystal is produced by crystallizing an anhydrous sodium carbonate crystal from an aqueous solution of sodium carbonate in the presence of 0.5 to 10 wt. % of sodium chloride and 0.3 to 20 wt. % of sodium hydroxide and separating the crystal from a mother liquor.
    Type: Grant
    Filed: January 19, 1981
    Date of Patent: September 20, 1983
    Assignee: Asahi Glass Company Ltd.
    Inventors: Keiichi Nakaya, Kohji Kawanami, Suekazu Hirata
  • Process for purifying sodium hydroxide
    Patent number: 4065270
    Abstract: An aqueous solution of sodium hydroxide containing soluble impurities such as a concentrated catholyte produced by a diaphragm electrolysis is cooled by a coolant or a heat-exchanger to form a slurry containing sodium hydroxide hydrate crystals and fine impurity crystals. The fine impurity crystals are adsorbed on bubbles which are formed by vaporizing a dissolved coolant or introducing a gas in the slurry and separated from the slurry.
    Type: Grant
    Filed: April 16, 1976
    Date of Patent: December 27, 1977
    Assignee: Asahi Glass Co., Ltd.
    Inventors: Keiichi Nakaya, Suekazu Hirata, Kunio Sato
  • Process for purifying sodium hydroxide
    Patent number: RE30411
    Abstract: An aqueous solution of sodium hydroxide containing soluble impurities such as a concentrated catholyte produced by a diaphragm electrolysis is cooled by a coolant or a heat-exchanger to form a slurry containing sodium hydroxide hydrate crystals and fine impurity crystals. The fine impurity crystals are adsorbed on bubbles which are formed by vaporizing a dissolved coolant or introducing a gas in the slurry and separated from the slurry.
    Type: Grant
    Filed: April 28, 1978
    Date of Patent: October 7, 1980
    Assignee: Asahi Glass Company, Limited
    Inventors: Keiichi Nakaya, Suekazu Hirata, Kunio Sato