Method for purifying SiO2-particles

US6746655B1 · kind B1 · utility

Assignee

• HERAEUS QUARZGLAS GMBH & CO. KG · DE

Inventors

• Jörg Becker · Florstadt, DE
• Joachim Nowak · Nidderau, DE

Key dates

• Filing date: Jan 5, 2001
• Grant date: Jun 8, 2004
• Expiry date: Jan 5, 2021

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C01P2006/80
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

In a known method for the cleaning of SiO2 grain, a fill of particles in a reactor having a vertically oriented center axis will be heated and simultaneously exposed to a treatment gas which is passed at a specified flow velocity from the bottom to the top through the reactor and the fill. To provide on this basis an improved cleaning method and a suitable simple device for it, it is proposed according to the invention and with regard to the cleaning method that a chloric treatment gas will be used which is set to a treatment temperature of at least 1,000° C. in the area of the fill, and that the flow velocity is set to at least 10 cm/s. With regard to the device according to the invention for the implementation of the method according to the invention, a gas shower is provided for the gas inlet, the gas shower comprising below the fill a multitude of nozzle openings distributed laterally to the center axis, for introduction of the treatment gas into the fill. The SiO2 grain of naturally occurring raw material and cleaned according to the invention is characterized by an iron content of less than 20 ppb by weight, preferably less than 5 ppb; a manganese content of less than 30 …