Method for cleaning a waste gas from a metal reduction process

Patent metadata

Field	Value
Publication number	US-2017120184-A1
Application number	US-201514770063-A
Country	US
Kind code	A1
Filing date	Jun 25, 2015
Priority date	Jul 3, 2014
Publication date	May 4, 2017
Grant date	—

Abstract

Gaseous perfluorocarbons in a waste gas are adsorbed by an adsorption device. Subsequently a decomposition of the perfluorocarbons takes place with formation of hydrogen fluoride. The hydrogen fluoride is converted with an oxide of a metal to be reduced, to the metal fluoride thereof. The metal fluoride formed is then fed again to the reduction process.

First claim

1 - 9 . (canceled)

10 . A method for cleaning a waste gas from a metal reduction process, comprising:
adsorbing gaseous perfluorocarbons in the waste gas by an adsorption device; forming hydrogen fluoride by decomposing the perfluorocarbons obtained from said adsorbing; converting the hydrogen fluoride, using an oxide of a metal to be reduced, to a metal fluoride of the metal to be reduced; and feeding the metal fluoride formed by said converting to the metal reduction process.

11 . The method as claimed in claim 10 ,
further comprising detecting perfluorocarbons by a sensor system, and wherein the waste gas is supplied to the adsorption device if a pre-set limit value of the gaseous perfluorocarbons is exceeded.

12 . The method as claimed in claim 10 , wherein the adsorption device is operated according to a pressure swing adsorption principle.

13 . The method as claimed in claim 10 , wherein the adsorption device is operated according to a temperature swing adsorption principle.

14 . The method as claimed in claim 10 , wherein adsorption materials in the adsorption device are selected from the group consisting of activated carbon, carbon nanotubes and a molecular sieve.

15 . The method as claimed in claim 10 , wherein adsorption materials in the adsorption device include silicalite-1.

16 . The method as claimed in claim 10 , wherein said forming of the hydrogen fluoride is by thermally decomposing the perfluorocarbons.

17 . The method as claimed in claim 10 , wherein the perfluorocarbons are decomposed by a plasma device.

18 . The method as claimed in claim 10 ,
wherein said adsorbing uses at least two adsorption devices, and wherein said method further comprises alternately charging and discharging the at least two adsorption devices.

19 . The method as claimed in claim 10 , further comprising discharging the adsorption device by at least one of a temperature change and a pressure change.

Assignees

• Siemens Ag

Inventors

• Friedrich Bernd
• Hanebuth Marc
• Tremel Alexander
• Vogel Hanno

Classifications

• Y02C20/30

  of perfluorocarbons [PFC], hydrofluorocarbons [HFC] or sulfur hexafluoride [SF6] · CPC title

• B01D2253/116

  Molecular sieves other than zeolites · CPC title

• B01D2259/818

  Employing electrical discharges or the generation of a plasma · CPC title

• B01D2253/102

  Carbon · CPC title

• B01J20/3416

  of sorbents or filter aids comprising free carbon, e.g. activated carbon · CPC title