초록 ▼

A method for recovery of fluoride values from spent potlining and fluoride containing insulating materials associated with the potlining is disclosed. Spent potlining and the insulating materials are reduced to a fine particle size and incinerated. The ash residue is leached with a dilute caustic an

A method for recovery of fluoride values from spent potlining and fluoride containing insulating materials associated with the potlining is disclosed. Spent potlining and the insulating materials are reduced to a fine particle size and incinerated. The ash residue is leached with a dilute caustic and the leachate is treated with a calcium compound to precipitate calcium fluoride. The calcium fluoride is dried to a moisture content of less than 0.1 percent and is treated with about 93 to 99 percent concentration of sulfuric acid to produce hydrogen fluoride gas and a metal sulfate. The hydrogen fluoride gas is fed into an alumina dry scrubber to produce alumina with absorbed fluorides to be used as feed material to reduction cells used in the manufacture of aluminum by electrolytic reduction. The metal sulfate residue is treated with lime and constitutes an environmentally safe product which can be disposed of as landfill material.

대표청구항 ▼

A method for producing a product capable of use as a feed material to a reduction cell used in the manufacture of aluminum by electrolytic reduction by recovering fluoride values from spent potlining of said cell comprising: (a) reducing a carbon-containing spent potlining to a fine particle size; (

A method for producing a product capable of use as a feed material to a reduction cell used in the manufacture of aluminum by electrolytic reduction by recovering fluoride values from spent potlining of said cell comprising: (a) reducing a carbon-containing spent potlining to a fine particle size; (b) incinerating said fine particles of potlining to destroy any cyanides which may be present in said potlining and form an ash residue, said carbon providing a substantial portion of the fuel required for incineration; (c) leaching said ash residue to remove fluorides therefrom; (d) treating said flurorides to form a hydrogen fluoride gas; (e) feeding said hydrogen fluoride gas to an alumina dry scrubber to produce a product; and (f) using said product as feed material to a reduction pot used to produce aluminum.