| 摘要 |
<p>Spent potliner from an aluminum reduction cell is subjected to an acid digest (24) and the digest may be adjusted to produce a first gas component comprised of at least one material selected from silicon tetrafluoride, hydrogen fluoride, hydrogen cyanide gas and water vapor (26) and a slurry component comprised of at least one material selected from carbon, silica, alumina, and sodium, iron, calcium and magnesium compounds. The first gas component is removed from the digester and heated to a temperature sufficiently high in a heater/oxidizer (38). Heat produced is recovered in a boiler (42). Hydrogen fluoride gas is water scrubbed (44) and formed into liquid hydrofluoric acid. Gases (56) from the water scrubber are then passed to a caustic scrubber (58) as a polishing step prior to release to the atmosphere.</p> |
