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Process for recovering CF4 and C2F6 from a gas

A C2F6, CO2 technology, applied in the field of aluminum production, can solve problems such as the increase of anode polarization voltage

Inactive Publication Date: 2000-02-16
LAIR LIQUIDE SA POUR LETUDE & LEXPLOITATION DES PROCEDES GEORGES CLAUDE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] (3) The polarization voltage of the anode is significantly increased;

Method used

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  • Process for recovering CF4 and C2F6 from a gas
  • Process for recovering CF4 and C2F6 from a gas
  • Process for recovering CF4 and C2F6 from a gas

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0072] Contains CF 4 、C 2 f 6 and N 2 The gas flow was in contact with the polyimide asymmetric composite hollow fiber membrane at various temperatures to determine the CF 4 、C 2 f 6 and N 2 relative permeability. This gas flow has a constant flow rate of 170 sccm. The pressure of the feed gas stream was maintained at 3 bar. The permeability of each of these components is shown in Figure 2. As can be seen from Figure 2, CF 4 / N 2 and C 2 f 6 / N 2 The selectivity is 300.

[0073] Based on the above selectivity, the single-stage membrane separation unit was simulated by computer. Concentration and pressure of feed, permeate and retentate, and CF 4 / C 2 f 6 The recoveries are shown in Table 1.

[0074] Feed

Embodiment 2

[0076] Using the feed concentrations and pressures listed in Table 2, the procedure of Example 1 was repeated. The simulation results are also listed in Table 2.

[0077] Feed

Embodiment 3

[0079] A typical smelting plant with 100 smelting tanks has an exhaust gas flow of 3Nm 3 / h. The procedure of Example 1 was repeated with this gas flow. The feed concentrations and pressures and simulation results for this stream are listed in Table 3.

[0080] Feed

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Abstract

A process for recovering at least one of CF4 and C2F6 from a vent gas from an aluminum electrolysis cell. The process includes the steps of: (a) removing inorganic fluorides from a vent gas comprising inorganic florides and at least one of CF4 and C2F6 to obtain a purified vent gas; and (b) contacting the purified vent gas with a membrane at conditions effective to obtain a retentate stream rich in at least one of CF4 and C2F6, and a permeate stream depleted in at least one of CF4 and C2F6.

Description

field of invention [0001] In general, the present invention relates to a gas separation process. Specifically, the present invention relates to a method for removing CF from gas streams using membranes 4 and C 2 f 6 at least one of the methods. The invention also relates to a method of producing aluminum comprising the removal of CF from a gas stream using a membrane 4 and C 2 f 6 at least one of. Background of the invention [0002] Currently, industrially, aluminum metal is produced in two steps. The first step involves the extraction of alumina (Al 2 o 3 ). The second step involves the reduction of alumina by the Hall-Heroult method, which is dissolved in molten cryolite (Na 3 AlO 6 ) and aluminum trifluoride (AlF 3 ) in the mixture. In the second step, aluminum-containing ions are reduced on the surface of the metal cathode to produce metallic aluminum. [0003] In the usual electrolysis process, anode carbon is consumed because oxygen-containing ions reac...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D53/22C25C3/22
CPCB01D2257/20C25C3/22B01D53/229
Inventor 李耀恩
Owner LAIR LIQUIDE SA POUR LETUDE & LEXPLOITATION DES PROCEDES GEORGES CLAUDE