Dry scrubbing tar and fluoride laden gases

Claim 1

A method of treating a gaseous stream containing fluoride and heavily laden with condensable carbonaceous matter comprising: a. introducing pulverulent alumina into a moving gaseous stream containing gaseous fluoride and heavily laden with condensable carbonaceous matter to entrain therein said alumina and to cause said carbonaceous matter to condense onto said alumina; b. directing said alumina containing gaseous stream into a chamber containing therein a foraminous plate and having pulverulent alumina disposed above said foraminous plate; c. passing said alumina-containing gaseous stream through said foraminous plate so as to maintain the alumina above said plate in a turbulent condition, thereby removing essentially all gaseous fluoride from the gaseous stream; and d. subsequently removing essentially all particulate matter from said gaseous stream.

Claim 2

A method of treating a gaseous stream containing fluoride and heavily laden with condensable carbonaceous matter comprising: a. introducing pulverulent alumina into a moving gaseous stream containing gaseous fluoride and heavily laden with condensable carbonaceous matter to entrain therein said alumina and to cause said carbonaceous matter to condense onto said alumina; b. directing said alumina containing gaseous stream into a chamber containing therein a foraminous plate and having pulverulent alumina disposed above said foraminous plate; c. passing said alumina-containing gaseous stream through said foraminous plate so as to maintain the alumina above said plate in a turbulent condition, thereby removing essentially all gaseous fluoride from the gaseous stream; and d. subsequently removing essentially all particulate matter from said gaseous stream.

Claim 3

A method of treating a gaseous stream containing fluoride and heavily laden with tar and/or condensable carbonaceous matter comprising: a. introducing pulverulent alumina into a moving gaseous stream of said effluent to entrain therein the pulverulent alumina and to cause said tar and/or carbonaceous matter to deposit and/or condense onto said alumina; b. directing the alumina containing gaseous stream to a chamber containing therein a foraminous plate and having pulverulent alumina disposed above said foraminous plate; c. passing the alumina containing gaseous stream through the foraminous plate so as to maintain the alumina above the plate in a turbulent condition and to thereby remove essentially all gaseous fluoride from the gaseous stream; and d. subsequently removing essentially all particulate matter from the gaseous stream.

Claim 4

A method of treating a gaseous stream containing fluoride and heavily laden with tar and/or condensable carbonaceous matter comprising: a. introducing pulverulent alumina into a moving gaseous stream of said effluent to entrain therein the pulverulent alumina and to cause said tar and/or carbonaceous matter to deposit and/or condense onto said alumina; b. directing the alumina containing gaseous stream to a chamber containing therein a foraminous plate and having pulverulent alumina disposed above said foraminous plate; c. passing the alumina containing gaseous stream through the foraminous plate so as to maintain the alumina above the plate in a turbulent condition and to thereby remove essentially all gaseous fluoride from the gaseous stream; and d. subsequently removing essentially all particulate matter from the gaseous stream.

Claim 12

A method of removing essentially all of the fluoride and tar and/or condensable carbonaceous matter from gaseous effluent from an aluminum reduction cell having a Soderberg-type electrode comprising a. withdrawing from the reduction cell a stream of gaseous effluent containing fluoride and tar and/or condensable carbonaceous matter; b. entraining pulverulent alumina into the essentially untreated gaseous stream withdrawn from the reduction cell to cause at least pat of the tar and/or carbonaceous matter therein to deposit and/or condense onto said entrained alumina; c. directing the alumina-containing gaseous stream to a chamber containing therein a foraminous plate and having pulverulent alumina disposed above the foraminous plate; d. passing the alumina-containing gaseous stream through the foraminous plate so as to maintain the alumina above the plate in a turbulent condition and thereby remove essentially all gaseous fluoride from the gaseous stream; and e. subsequently removing essentially all particulate matter from the gaseous stream.

Claim 13

A method of removing essentially all of the fluoride and tar and/or condensable carbonaceous matter from gaseous effluent from an aluminum reduction cell having a Soderberg-type electrode comprising a. withdrawing from the reduction cell a stream of gaseous effluent containing fluoride and tar and/or condensable carbonaceous matter; b. entraining pulverulent alumina into the essentially untreated gaseous stream withdrawn from the reduction cell to cause at least pat of the tar and/or carbonaceous matter therein to deposit and/or condense onto said entrained alumina; c. directing the alumina-containing gaseous stream to a chamber containing therein a foraminous plate and having pulverulent alumina disposed above the foraminous plate; d. passing the alumina-containing gaseous stream through the foraminous plate so as to maintain the alumina above the plate in a turbulent condition and thereby remove essentially all gaseous fluoride from the gaseous stream; and e. subsequently removing essentially all particulate matter from the gaseous stream.

Claim 14

A method of removing essentially all of the fluoride and tar and/or condensable carbonaceous matter from gaseous effluent from an anode baking furnace comprising a. withdrawing from the anode baking furnace a stream of gaseous effluent containing fluoride and tar and/or condensable carbonaceous matter; b. entraining pulverulent alumina into the essentially untreated gaseous stream withdrawn from the anode baking furnace to cause at least part of the tar and/or carbonaceous matter to deposit and/or condense onto said entrained alumina; c. directing the alumina-containing gaseous stream to a chamber containing therein a foraminous plate and having pulverulent alumina disposed above the foraminous plate; d. passing the alumina-containing gaseous stream through the foraminous plate so as to maintain the alumina above the plate in a turbulent condition and thereby remove essentially all gaseous fluorides from the gaseous stream; and e. subsequently removing essentially all particulate matter from the gaseous stream.

Claim 15

A method of removing essentially all of the fluoride and tar and/or condensable carbonaceous matter from gaseous effluent from an anode baking furnace comprising a. withdrawing from the anode baking furnace a stream of gaseous effluent containing fluoride and tar and/or condensable carbonaceous matter; b. entraining pulverulent alumina into the essentially untreated gaseous stream withdrawn from the anode baking furnace to cause at least part of the tar and/or carbonaceous matter to deposit and/or condense onto said entrained alumina; c. directing the alumina-containing gaseous stream to a chamber containing therein a foraminous plate and having pulverulent alumina disposed above the foraminous plate; d. passing the alumina-containing gaseous stream through the foraminous plate so as to maintain the alumina above the plate in a turbulent condition and thereby remove essentially all gaseous fluorides from the gaseous stream; and e. subsequently removing essentially all particulate matter from the gaseous stream.