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PATENT APPLICATION PUBLICATION
INDIA
Date of filing of Application: 08/01/1997
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Application No.: 52/DEL/1997
Publication Date:09/06/2006
(54) Title of the Invention: “AN IMPROVED PROCESS FOR PREPARATION OF OPTICAL WINDOW
GRADE ZINC SULPHIDE”
(51) International Classification : C 01 G 9/08
(31) Priority Document No. : NA
(32) Priority Date : NA
(33) Name of priority country : NA
(86) International application No. : NA
Filing Date : NA
(87) International Publication No. : NA
(61) Patent of Addition to
Application No.
:
N.A.
(62) Divisional to Application No. : NIL
Filed On : N.A.
Total No. of pages : 12
(71) Name of Applicant :
THE CHIEF CONTROLLER RESEARCH &
DEVELOPMENT,
Address of the Applicant: Technical
Coordination Dte., B-341, Sena Bhawan, DHQ
P.O. New Delhi – 110 011, India.
(72) Name of the Inventor:
Shambhoo Shankar Singh
Surendra Pratap
Jagdish Prasad
Rajeev Kumar
Krishna Murari
(57) Abstract: According to this invention there is an improved process for preparation optical window grade zunc sulphide comprising in
the steps of preparing stock solution by reacting Zinc Oxide with 2M H2 SO4 followed by addition of zinc granules and decanting, oxidizing
metallic impurities by addition H2 O2, reacting stock solution of 0.1 m to 0.8 M concentrated Zinc Sulphate (znSo4) with pure H2S gas,
characterised by the step of maintaining the pH of the reaction mixture to 2.4 + 0.1, firing at a temperature range of 700 0 C to 950 0 in an inert
atmosphere of preferably nitrogen to obtain Zinc Sulphide Powder.
The Patent Office Journal 09/06/2006 11117
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