A method of treating dust precipitated from waste gases from metallurgical processes in particular dust precipitated from waste gases in connection with the production of steel, in order to transfer the dust to a form in which it can be deposited without danger of environmental pollution and from which the valuable components of the dust can be recovered. According to the method, the dust is treated in the following steps: continuous supply of dust together with reducing agent and fluxes to a gastight covered electrothermic smelting furnace (1); smelting and selective reduction together with volatilisation of volatile metals in the smelting furnace (1); continuous or intermittent tapping of an inert slag phase (12) and a liquid metal phase (13) from the smelting furnace; continuous removal from the smelting furnace of a gas phase (8) containing chiefly CO-gas, metal fumes, sulphur, chlorides and fluorides together with entrained unreacted dust; optional selective condensation (10) of one or more meals from the metal fumes in he waste gas from the smelting furnace; controlled after burning (6) of oxydisable components in the waste gas; removal of dust (8) from the waste gas; and final purification and neutralisation (9) of the waste gas.
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