Method for reducing alumina or magnesia by utilizing supersonic gas flow

Patent metadata

Field	Value
Publication number	US-9617620-B2
Application number	US-201314421181-A
Country	US
Kind code	B2
Filing date	Mar 8, 2013
Priority date	Aug 22, 2012
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

An alumina- or magnesia-reducing process in which a greenhouse gas or substance harmful to the human body is not emitted, which can achieve improved energy efficiency in comparison with the Hall-Heroult or Pidgeon methods. The process includes: introducing an alumina or magnesia powder with a carrier gas to the upstream side of a throat provided on a reducing unit; pressure-transferring the powder and carrier gas to the throat by an operative gas introduced to the upstream side of the throat; irradiating the throat with a laser beam to convert the alumina or magnesia into a plasma state and dissociate the alumina or magnesia thermally; jetting the thermally dissociated product through a nozzle provided on the downstream side of the throat at a supersonic speed to form a frozen flow; and isolating aluminum or magnesium. Hydrogen may be added to the operative gas to accelerate the reduction of alumina or magnesia.

First claim

What is claimed is:

1. A method for reducing alumina or magnesia, the method comprising:
heating alumina powders or magnesia powders by heating means for putting it in a plasma state so as to thermally dissociate aluminum or magnesium from oxygen, and
ejecting gas in the plasma state in a form of a supersonic jet steam from a nozzle so as to make it in frozen flow, to thereby isolate aluminum or magnesium.

2. The method for reducing alumina or magnesia as described in claim 1 , wherein;
alumina powders or magnesia powders are fed into a reducing device together with carrier gas at upstream of a throat portion provided to the reducing device,
operating gas is introduced similarly at upstream of the throat portion, gas pressure of which forcedly transport the fed powders toward the throat portion,
heating means heats the throat portion, thereby dissociating alumina or magnesia which is then ejected in a form of the supersonic jet gas stream from the nozzle located at downstream of the throat portion.

3. The method for reducing alumina or magnesia as described in claim 2 , wherein hydrogen is added to the operating gas so as to promote reducing alumina or magnesia by action of the added hydrogen.

4. The method for reducing alumina or magnesia as described in claim 3 , wherein the heating means is laser beam.

5. The method for reducing alumina or magnesia as described in claim 2 , wherein the method further includes a step of further comprising controlling volume of alumina powders or magnesia powders to be fed at upstream of the throat portion.

6. The method for reducing alumina or magnesia as described in claim 5 , wherein the heating means is laser beam.

7. The method for reducing alumina or magnesia as described in claim 2 , wherein the method further includes a step of further comprising guiding isolated aluminum or magnesium into a cooling tube so as to deposit aluminum or magnesium inside of the cooling tube and collect the same, or a step of collecting the isolated aluminum or magnesia by using a filtering device.

8. The method for reducing alumina or magnesia as described in claim 7 , wherein the heating means is laser beam.

9. The method for reducing alumina or magnesia as described in claim 2 , wherein the heating means is laser beam.

10. The method for reducing alumina or magnesia as described in claim 1 , wherein the heating means is laser beam.

Assignees

• Japan Expert Clone Corp
• Univ Tokyo
• Tokyo Metropolitan Univ Municipal Univ Corp

Inventors

• Arakawa Yoshihiro
• Nakano Masakatsu
• Matsui Makoto
• Goto Tetsuya

Classifications

• C22B5/12

  by gases · CPC title

• C22B21/02

  with reducing {(C22B21/04 takes precedence)} · CPC title

• C22B26/22 Primary

  Obtaining magnesium · CPC title

• C22B21/04

  with alkali metals {earth alkali metals included} · CPC title

• C22B4/02

  Light metals {(C22B4/005 takes precedence)} · CPC title