초록 ▼

Spent potliner from an aluminum reduction cell is subject to an acid digest and the digest may be adjusted to produce a first gas component comprised of at least one material selected from the group consisting of silicon tetrafluoride, hydrogen fluoride, hydrogen cyanide gas and water vapor, and a s

Spent potliner from an aluminum reduction cell is subject to an acid digest and the digest may be adjusted to produce a first gas component comprised of at least one material selected from the group consisting of silicon tetrafluoride, hydrogen fluoride, hydrogen cyanide gas and water vapor, and a slurry component comprised of at least one material selected from the group consisting of 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 to convert said silicon tetrafluoride to fumed silica and hydrogen fluoride. Thereafter, the fumed silica is separated from the hydrogen fluoride to recover fumed silica from spent potliner material.

대표청구항 ▼

[What is claimed is:] [1.](a) digesting the spent potliner material in an acid digester to produce a first gas component comprised of silicon tetrafluoride and hydrogen fluoride, and at least one material selected from the group consisting of hydrogen cyanide gas and water vapor, and a slurry compon

[What is claimed is:] [1.](a) digesting the spent potliner material in an acid digester to produce a first gas component comprised of silicon tetrafluoride and hydrogen fluoride, and at least one material selected from the group consisting of hydrogen cyanide gas and water vapor, and a slurry component comprised of at least one material selected from the group consisting of carbon, silica, alumina, and sodium, iron, calcium and magnesium compounds;(b) removing said first gas component from said digester;(c) heating said first gas component recovered from said digester to a temperature sufficiently high to convert said silicon tetrafluoride to fumed silica and hydrogen fluoride; and(d) separating said fumed silica from said hydrogen fluoride to recover fumed silica from spent potliner material.