The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 14, 1989
Filed:
Jun. 23, 1986
Emmanuel Papanikolau, Eindhoven, NL;
Leonard T Ebben, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
Starting from pegmatitic sand, the invention provides a method of purifying quartz sand, in which the amount of iron is reduced to less than 0.3 ppm, the amount of zircon to less than 1 ppm, and the amount of phosphor to less than 0.2 ppm. Gas nuclei are also removed. The method is carried out by washing with solution which contains at least 15% by weight of HF in water until at least 40% by weight of the quartz sand is dissolved, and washing with a solution which contains at least 20% by weight of HCl in water at a temperature from 5.degree. to 95.degree. C. for at least 30 minutes. In this method, the grains of the sand are freely suspended in an upward stream of the acid. Such quartz sand can suitably be used for the manufacture of very pure quartz glass for use in mercury discharge lamps, in glass fibers for telecommunication purposes (cladding glass), or in semiconductor arrangements.