Declogging process for filtration installation and improved filtration installation

Claim 2

In a method of pneumatically declogging a filtering element of a filtration installation in which dust-laden gas having reducing properties is passed through the filtering element whereby dust is deposited on the filtering element and dust-free gas issues therefrom and in which a flow of inert gas is periodically used to dislodge and deposited dust, the improvement wherein said inert gas is obtained by oxidizing a portion of the dust-free gas issuing from the filtering element.

Claim 3

An improved method according to claim 1 wherein the inert gas is used to heat a fluid before being used to dislodge said deposited dust.

Claim 4

An improved process according to claim 2 wherein said dust-laden gas is generated in a metal refining furnace, wherein said metal refining furnace is charged with material discharged from a roasting furnace, wherein said roasting furnace is charged with a mineral or metal oxide charge, wherein said fluid heated by said inert gas comprises oxidizing gas which is thereafter introduced into said roasting furnace, and wherein a portion of the dust-free gas issuing from said filtering element is introduced into said roasting furnace.

Claim 5

An improved method according to claim 3 wherein the dust-laden gas, prior to filtration, is used to heat an oxidizing gas, and wherein the heated oxidizing gas is introduced into said roasting furnace.

Claim 6

An improved method according to anyone of claims 1-4 wherein the inert gas flow is filtered upstream of said filter element.

Claim 7

In filtration apparatus comprising filtering element means for filtering dust-laden gas having reducing properties, means for passing said gas through said filtering element means whereby dust is deposited on said filtering element means and dust-free gas issues therefrom, and means for periodically introducing a flow of inert gas through said filtering element means in a direction opposite to the direction of flow of said dust-laden gas to dislodge said deposited dust, the improvement which comprises means for oxidizing a portion of the dust-free gas issuing from the filtering element means to obtain said inert gas, and means for supplying the oxidized, inert, gas, to said inert gas flow introducing means.

Claim 8

In filtration apparatus comprising filtering element means for filtering dust-laden gas having reducing properties, means for passing said gas through said filtering element means whereby dust is deposited on said filtering element means and dust-free gas issues therefrom, and means for periodically introducing a flow of inert gas through said filtering element means in a direction opposite to the direction of flow of said dust-laden gas to dislodge said deposited dust, the improvement which comprises means for oxidizing a portion of the dust-free gas issuing from the filtering element means to obtain said inert gas, and means for supplying the oxidized, inert, gas, to said inert gas flow introducing means.

Claim 9

Improved apparatus according to claim 6 further comprising heat exchange means in flow communication with said oxidizing means to heat a fluid by said inert gas prior to supplying said inert gas to said inert gas flow introducing means.

Claim 10

Improved apparatus according to claim 7 further comprising a metal refining furnace for generating said dust-laden gas, a roasting furnace, means for charging said metal refining furnace with material discharged from said roasting furnace, means for charging said roasting furnace with a mineral or metal oxide charge, means for introducing the fluid heated by said inert gas into said roasting furnace, and means for introducing a portion of the dust free gas issuing from said filtering element into said roasting furnace.

Claim 11

Improved apparatus according to claim 8 further comprising further heat exchange means for heating an oxidizing gas by the dust-laden gas prior to filtration thereof, and means for introducing the heated oxidizing gas into said roasting furnace.

Claim 12

Improved apparatus according to any one of claims 6-9 further comprising means for filtering said inert gas in flow communication with said oxidizing means and said supply means.