Patents by Inventor Vijayalakshmi Ravishankar

Vijayalakshmi Ravishankar 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 recovery of high purity uranium from fertilizer grade weak phosphoric acid
    Patent number: 7192563
    Abstract: A two-cycle countercurrent extraction process for recovery of highly pure uranium from fertilizer grade weak phosphoric acid. The proposed process uses selective extraction using di-(2-ethyl hexyl) phosphoric acid (D2EHPA) and tri-n-butyl phosphate (TBP) with refined kerosene as synergistic extractant system on hydrogen peroxide treated phosphoric acid, and stripping the loaded extract with strong phosphoric acid containing metallic iron to lower redox potential. The loaded-stripped acid is diluted with water back to weak phosphoric acid state and its redox potential raised by adding hydrogen peroxide and re-extracted with same extractant system. This extract is first scrubbed with sulfuric acid and then stripped with alkali carbonate separating iron as a precipitate, treated with sodium hydroxide precipitating sodium uranate, which is re-dissolved in sulfuric acid and converted with hydrogen peroxide to highly pure yellow cake of uranium peroxide.
    Type: Grant
    Filed: March 31, 2002
    Date of Patent: March 20, 2007
    Assignee: Secretary, Department of Atomic Energy, Government of India
    Inventors: Harvinderpal Singh, Shyamkant Laxmidutt Mishra, Anitha Mallavarapu, Vijayalakshmi Ravishankar, Ashok Baswanthappa Giriyalkar, Manojkumar Kedarnath Kotekar, Tapan Kumar Mukherjee
  • Process for recovery of high purity uranium from fertilizer grade weak phosphoric acid
    Publication number: 20040247504
    Abstract: A two-cycle countercurrent extraction process for recovery of highly pure uranium from fertilizer grade weak phosphoric acid. The proposed process uses selective extraction using di-(2-ethyl hexyl) phosphoric acid (D2EHPA) and tri-n-butyl phosphate (TBP) with refined kerosene as synergistic extractant system on hydrogen peroxide treated phosphoric acid, and stripping the loaded extract with strong phosphoric acid containing metallic iron to lower redox potential. The loaded-stripped acid is diluted with water back to weak phosphoric acid state and its redox potential raised by adding hydrogen peroxide and re-extracted with same extractant system. This extract is first scrubbed with sulfuric acid and then stripped with alkali carbonate separating iron as a precipitate, treated with sodium hydroxide precipitating sodium uranate, which is re-dissolved in sulfuric acid and converted with hydrogen peroxide to highly pure yellow cake of uranium peroxide.
    Type: Application
    Filed: February 11, 2004
    Publication date: December 9, 2004
    Inventors: Harvinderpal Singh, Shyamkant Laxmidutt Mishra, Anitha Mallavarapu, Vijayalakshmi Ravishankar, Ashok Giriyalkar, Manojkumar Kedarnath Kotekar, Tapan Kumar Mukherjee